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With the rapid growth of renewable energy sources (RES) in the power generation mix in accordance with the German energy transition policy (‘Energiewende’), fewer baseload coal power plants will be required. Future power generation will be supplied through decentralized power utilities such as off-shore wind parks and also through high operational flexibility of existing conventional coal power units. High operational flexibility means conventional power plants have to increase cyclic operations to cope with feed-ins from variable-RES such as wind and solar.
Unlike medium and peak load power plants that can react quickly to load changes and power ramps, baseload power plants are not suited for such operations. Important technical requirements for flexible operation include among others; frequent start-ups and shut-downs, a minimum downtime, shorter startup time and short operational periods. Baseload coal power plants however do not meet these requirements.
This increased cyclic mode of operation can have severe impacts on vital power plant components such as superheater and reheater tubes resulting in high temperature cyclic oxidation/corrosion especially because these plants were not designed for frequent cyclic operations. To optimize plant operations, minimize material damage and reduce operational and maintenance cost, it is therefore important to understand the oxidation and corrosion risk to plants materials associated with this flexible mode of operation.
In this context, thermochemical modeling in FactSage 6.4ᵀᴹ as well as experimental investigations were carried out. For the experimental investigations, five commercial coal boiler superheater and reheater materials, namely T91, VM12-SHC, TP347-HFG, DMV304 HCu and DMV310 N were exposed for 1000 hours under discontinuous isothermal oxidation conditions and 1000 hours thermo–cyclic oxidation conditions at a metal surface temperature of 650 °C. The synthetic corrosive flue gas consisted of a mixture of CO₂, O₂, SO₂, N₂ and H₂O. The test material samples were partly covered in fly ash to investigate the effect ash deposits on the corrosion and oxidation behavior of the test materials. After exposure metallographic analysis by means of light microscopy and scanning electron microscopy (LOM and SEM–EDS) were carried out to study the oxide morphology and micro–structural properties of the materials. The oxidation kinetics (weight change) results showed significant oxide growth rates (weight gain) under cyclic oxidation conditions especially in the martensitic alloys – T91, VM12-SHC.
Furthermore, metallographic analysis revealed severe oxide spallation in the ash covered sections of these alloys. The austenitic materials (TP374-HFG, DMV310 N) with the exception of DMV304 HCu showed good oxidation behavior with minimal oxide growth both under isothermal and thermal cyclic conditions. However, severe grain boundary attack and internal sulphidation were found in these alloys. DMV310 N showed the best corrosion and oxidation performance. The thermochemical modeling calculations supported the experimental results.
In arid countries, reclaimed water in irrigation is a widespread practice. Therefore, robust treatment designs are prerequisite to obtain effluent quality that conforms to the legal requirements for reuse and health standards. Vertical flow constructed wetlands (VFCWs) are attractive decentralized treatment plants in many countries and communities. VFCWs are capable of providing adequate treatment for organic and solids removal, even though there are limitations on nutrient and pathogen removal. Within this study, various VFCW systems were investigated, in Germany and Jordan, to optimize nitrogen removal using sustainable and low cost options to guarantee the safe reuse in Jordan.
In Germany at Langenreichenbach research facility, two-stage VFCWs planted (Phragmites australis) and unplanted were evaluated and modified to compare the role of plants over two years. Generally, there was no significant role of plants on the treatment performance. Both systems showed high removal efficiency for TOC, BOD5, and TSS over the study period. During the first year of the study, effluent TN concentrations ranged from 60 - 61 mg/L in both systems as a result of high effluent NO3--N concentrations (50 - 52 mg/L). In the second year, the systems were modified, adopting a saturated layer in the 1st stage to enhance denitrification. Average effluent TN concentrations were reduced to 45 mg/L in both systems. In addition, during modifications, the E.coli removal was enhanced in both systems achieving 4 log reduction instead of 2 log reduction during the first year of the study.
In Jordan at the Fuhais research facility, two VFCW systems were studied considering category-A (TN: 45 mg/L and NO3-N: 30 mg/L) in the Jordanian Standards for reuse in irrigation (JS 893/2006). Recirculating (ECO-1) and Multi-stage (ECO-2) VFCW designs have shown high removal efficiency of COD, TSS, and BOD5 over three years of monitoring. ECO-1 system combines simultaneous nitrification and denitrification by recycling portion of nitrified effluent into the recirculation tank. However, effluent TN and NO3--N concentrations were 55 and 44 mg/L, respectively, that the system conformed to the JS category-B (TN: 70 mg/L and NO3-N: 45 mg/L) during monitoring phase. Therefore, ECO-1 was modified by installing plastic media in the recirculation tank that attached growth increases the abundance and activity of microorganisms. TN concentration was reduced effectively of 40 mg/L, conforming to the JS category-A, whereas, NO3--N concentration was reduced to 37 mg/L, conforming to the JS category-B. However, over the study period, E.coli concentrations were conformed to the JS category-C (more than 1000 MPN/100 mL).
ECO-2 consists of two unsaturated VFCWs in series; single-pass unplanted filter followed by planted filter (Phragmites australis). E.coli removal was relatively high before modification that the effluent conformed to the JS (category-B: 1000 MPN/100 mL), achieving 4.4 log reduction. The effluent TN and NO3--N concentrations did not conform to the JS of 77 and 76 mg/L, respectively, due to insufficiency of carbon source to promote denitrification (high BOD5 removal) during monitoring phase of the study. Thus, ECO-2 was modified adopting raw wastewater step-feeding strategy that a specific volume of raw wastewater was mixed with 1st stage effluent in the mixing tank. TN and NO3--N concentrations were reduced to 52 and 50 mg/L, respectively; conforming to the JS category-B. Whereas, E.coli removal was influenced by E.coli ingress from raw step-feeding, achieving 3.5 log reduction, conforming to the JS category-C.
The short-term impact of irrigation with different water quality and quantity was investigated at the Fuhais site. Soil physicochemical and biological properties in three parallel experimental reuse plots were investigated. The plots were cultivated with lemon trees and were irrigated via a subsurface irrigation system. Moreover, each plot was divided into two subparts (A and B) whereby one part received 11 mm/day of irrigation water and the other received 6 mm/day. Using treated effluent and tap water showed the same trend of increased soli salinity (ECs). Significant difference in ECs, SAR, Mg+2, Ca+2, and Na+ were observed at 0-20 cm as a result of high evaporation and capillary rise that increased salts accumulation in the topsoil. However, using more water reduced the salts accumulation in sub soil layers due to continuous leaching. Whereas, results showed no significant variation in soil texture, structure, moisture, and infiltration rate among reuse plots and subparts. Additionally, results revealed an absence of total coliform, fecal coliform, and E.coli in the irrigated soils, indicating the effectiveness of using subsurface irrigation as a disinfection step for reuse.
Scientific data and results have to be accurate, precise and reliable and are subject to ever increasing scrutiny by regulators in industry, the environment and medicine, in validation and also in research and development. Given our numerous environmental problems, the need for accurate, precise and reliable results can not be overemphasized in environmental pollution control. In the light of this analytical environmentalists believe that there is need for a hierarchical scheme of methods to be used in environmental assessment studies. In this research the state and role of analytical instruments in environmental pollution control in Nigeria were studied with a focus on the state of the Nigerian environmental pollution control laboratories. A theoretical background of this work gives an overview of the state of the art of the environment globally and that of Nigeria. This work has established that, because mankind have put thousands of chemical substances to use in this century, there are many chemicals that have found their way into the natural environment in large quantities. Because of the nature of the environmental problems mankind is facing now, many researchers and manufacturers are dedicated to using and providing quality new and reliable instrumentation methods to ensure a healthy environment in our world. A brief study of Nigeria as the country of research is made to establish the background of possible problems. From the facts gathered in the literature Nigeria has the economic tools that it needs to put a good environmental management scheme in place, which includes good standards, laws, regulations and good analytical laboratories for compliance and monitoring. However the research has established that these economic tools are not effectively used in the management of environmental pollution control, especially monitoring of environmental pollutants. The research was undertaken by visiting four analytical laboratories involved in environmental pollution control in Nigeria, and three organizations that are the main environmental regulatory bodies in Nigeria. The analytical laboratories visited are those of Nigerian National Petroleum Corporation (NNPC) Kaduna, Ashaka cement factory, regional laboratory of the Federal Ministry of Water Resources Gombe, and the National Reference laboratory Lagos. In these laboratories and the organizations, results were collected in the laboratories, interviews were carried out and analytical instruments available were documented. It was discovered that, in these laboratories many standard analytical instruments needed for quality environmental pollution control and monitoring are lacking. Comparison of results generated in these laboratories with some from developed countries, revealed that many parameters measured in laboratories in developed countries are not measured in the research laboratories. The results obtained in these laboratories met Nigeria’ maximum limits in some cases, but exceeded it in many cases. It is the position of this work that the gap between the environmental analytical instruments found in literature and developed countries, and that found in Nigeria is very large and calls for concern. The environmental regulatory bodies in Nigeria have many laws, rules, regulations and standards for environmental pollution control. These regulations, standards, laws and rules were compared with what is obtained in other countries of the world, especially developed countries and found to be lacking in many areas. The way and manner the analytical methods are stated in the Nigerian regulations and standards are way below the developed countries standard. This research concludes that the regulations and standards have big influence on the kind of environmental analytical instruments found in the environmental analytical laboratories in Nigeria. The final conclusion this study has reached is that analytical methods, equipments, and standards on ground in Nigeria are not sufficient for the purpose of good environmental pollution control and monitoring. The situations as regards analytical instruments, analytical methods, standards and guidelines used in environmental pollution control in Nigeria do not favourably compare to international situations. It is therefore recommended that the need for validity and reliability in data collection, analysis, guidelines, standards and use of data in environmental pollution control needs to be addressed by the Nigerian Government if monitoring of the Millennium Development Goals and environmental pollution control in general is to be effective.
Niemand flieht freiwillig, dass heißt, wenn sich Menschen zur Flucht entscheiden, so geschieht dies immer unter dem Druck einer Situation, die als aussichtslos und unerträglich empfunden wird. Jahr für Jahr verlassen mehrere Millionen Menschen ihre Heimat in der Hoffnung auf ein besseres Leben in einem anderen Land. Die Globalisierung von Wirtschaft und Technologien sowie politische oder militärische Krisen zwingen sie dazu. Krieg, politische Repressionen oder Mangel an Lebensperspektiven im Herkunftsland machen eine Rückkehr unmöglich. So sind die weltweit zunehmenden Migrationsströme ein untrügliches Zeichen für soziale Ungleichheit und Benachteilung in der Welt. Umweltflüchtlinge sind nicht nur eine Folge der Umweltzerstörung durch natürliche oder vom Menschen und seiner Industrie entstandene Umweltkatastrophen, sondern auch eine Folge des Bevölkerungswachstums. Dadurch kommt es zu einer dramatischen Überbeanspruchung landwirtschaftlicher Flächen, die letztlich ebenfalls zu deren Zerstörung führt. Obwohl das Stichwort der Bevölkerungsexplosion in aller Munde ist, scheint bisher weithin unerkannt zu bleiben, wie dramatisch diese Entwicklung in den vergangenen Jahrzehnten verlaufen ist. Und den Entwicklungsländern fehlen jegliche Kapazitäten, dieser Entwicklung ökonomisch und ökologisch entgegenzuwirken. Die in der letzten Zeit erarbeiteten alternativen Strategien zu einer Lösung des Palästinakonfliktes sind vor folgendem Hintergrund zu sehen: Bis Anfang der 90er Jahre wurden seit 1967 besetzte Gebiete von Israel beansprucht. Unter dem geänderten Bewusstsein der Weltöffentlichkeit werden die palästinensischen Territorien aber nun als von Israel strukturell eigenständige Einheit betrachtet. Nach dem langjährigen Konflikt zwischen Palästinensern und Israelis rückte durch den Friedensprozess die Frage nach der Zukunft der im Jahr 1967 besetzten Gebiete wieder ins Bewusstsein der Weltöffentlichkeit. Seither haben Bombardierungen und Abriegelungen vor allem des Gaza-Streifens jedoch zu einer weiteren Verschärfung der Krise geführt. Eine Lösung des Konfliktes muss dringend gefunden werden, weil nur dadurch auch eine Verbesserung des Lebensstandards der Menschen im Westjordanland und im Gaza-Streifen erreicht werden kann. Als Ergebnis des Oslo-Abkommens von 1994 entstand die palästinensische Selbstverwaltung (PNA), zu deren vorrangigen Zielen es gehört, die Lebensbedingungen in den Autonomiegebieten zu verbessern und die angeschlagene Wirtschaft zu fördern. Nach Erläuterung dieser politischen Prozesse in der Region konzentriert sich die Arbeit auf eine Diskussion über die dringend benötigte Entwicklung in der Region Gaza-Streifen, die als Teilgebiet eines zukünftigen palästinensischen Staates bisher umfangreiche Probleme und eine wahrhaftig deutliche Unterentwicklung erfahren hat. Die Sicherung der ökologischen Zukunft des Menschen ist eine zentrale Aufgabe für dienächsten Jahre. Zu unserem Wohl und vor allem auch zum Wohl der nachfolgenden Generationen darf sich Umweltpolitik nicht darauf beschränken, bereits eingetretene Umweltschäden zu beseitigen. Vielmehr müssen die Aspekte Natur und Ökosysteme zukünftig ganz selbstverständlich in alle Planungen und Maßnahmen des Menschen einbezogen werden. Umweltschutz ist Daseinsvorsorge. Folglich darf sie nicht nur als Schadensbeseitigung angesehen werden, sondern muss offensiv auf die Verhinderung umweltbelastender Entwicklungen abzielen. In diesem Zuge ist auch die Abfallbeseitigung zu einem zentralen Anliegen des Umweltschutzes geworden. Ein verantwortungsbewusster Umgang mit der Natur und den Ressourcen ist prinzipiell nur möglich, wenn Abfallstoffe, soweit sie nicht vermieden werden können, durch eine sinnvolle Verwertung möglichst weitgehend in den natürlichen Stoffkreislauf zurückgeführt werden. Der wesentliche Bestandteil einer geordneten Entsorgungswirtschaft ist die Absicherung ökonomisch und ökologisch vertretbarer Entsorgungswege. Eine hohe Entsorgungssicherheit bei vertretbaren Kosten ist einer der Faktoren, die die Qualität eines Wirtschaftsstandortes verbessern. Für eine vernünftige Abfallwirtschaftsplanung sind die zukünftig zu erwartenden Abfallmengen abzuschätzen, die durch das Wirtschaftswachstum sowie die Bevölkerungsentwicklung bestimmt werden. Die gesetzlichen Rahmenbedingungen bestimmen die Zusammensetzung der Abfälle und über die Regelungen der Überlassungspflicht letztendlich die zu beseitigenden Abfallmengen.
The Banyang-Mbo Wildlife Sanctuary is a multiple-use lowland tropical rainforest in South West of Cameroon. This area was designated by the government of Cameroon with a focus of protecting 11 species including the most endangered primates in Central and West Africa, the Drill (Mandrillus leucophaeus) and Chimpanzees (Pan troglodytes). Local communities maintain user-rights of the forest and its natural resources as long as the conservation goals of the protected areas are not compromised. With many villages in and around the sanctuary and an ever-increasing population, most villagers rely on bushmeat to meet both dietary requirements and as a source of income. The purpose of the six-month study was to assess the current impact of hunting pressure on wildlife biodiversity loss with hope to recommend managed sustainable hunting system to the Ministry of Forestry and Wildlife. Carcasses of animals brought in daily by the eighty-four hunters who participated in the study were weighed, sexed and aged and socio-economic data collected by recording weapon type, use, price of each animal killed and its destination by 14 research assistants in 14 study villages. Hunters were interviewed in an attempt to understand hunters' perception of hunted game and their capacity to implement a managed hunting system. Study results indicated that 44 animal species were harvested with a total of 3,176 individual animals killed, giving an estimated total biomass of 22,397 kg in both the Banyang and Mbo areas. The Banyang ethnic group registered more harvest in terms of both off-take 1,888 animals and biomass 13,476 kg (13.5 tons) while the Mbo ethnic group extracted 1,288 animals with a biomass of 8,921.02 kg (9.00 tons) over the six-month study period. When placed into taxonomic groups, duikers constituting (34%), rodents (22%), other protected species (15%) and monkeys (11%) of the total animals extracted were most affected by hunting within the whole of BMWS. Larger-bodied animals like primates and duikers were most vulnerable to gun hunting while smaller carnivores and rodents were more vulnerable to wire snaring and trapping. Poisoned baits were used in some villages to trap Cane rats and Monkeys. Hunting peaks were attained during the raining season especially during the months of July and August. However, some small peaks occurred during the dry season especially in the months of November and January. More males (47%) were killed than females (43%) for all species over the six-month study period. Unknown sex constituted (10%) of the total extracted animals registered. Adults comprised (69%) of the total catch for all species registered, juveniles and infants constituted (23%) and (8%) respectively. Generally the Banyang ethnic group either consumed or sold locally (83%) of their total harvested bushmeat and sold only (11%) to outside traders. The Mbo ethnic group consumed or sold locally (47%) of the total bushmeat killed and sold (39%) to outside bushmeat dealers. Economic gains in terms of financial income from sale of bushmeat at the Banyang-Mbo Wildlife Sanctuary do not seem to be profitable as one hunter earned on average 22.629F CFA (US $47) per month over the study period compared to 125.000F CFA (US $258) earned by an average civil servant in Cameroon. One kilogramme of the most expensive bushmeat such as Pangolin (Manis gigantea) and Brush-tailed porcupine (Atherurus africanus) was on the average about 4.7 times less expensive than the price of one kg of domesticated animals such as fresh cow beef or goat meat. The Drill (Mandrillus leucophaeus) and the Chimpanzee (Pan troglodytes) are at high risk of local extinction in this area. Meanwhile species like the Leopard (Panthera pardus), Buffalo (Syncerus nanus), the African Elephant (Loxodonta africana) and the Giant pangolin (Manis gigantea) were not recorded killed in any of the 14 study villages and are feared to be locally extinct. There was a steady decline in off-take and biomass of large-bodied species like duikers and primates in the total harvest of both ethnic groups over time during the study period. This suggests that hunting of larger-bodied animals may not be sustainable within the Banyang-Mbo Wildlife Sanctuary. The future of Blue duikers seems bleak if hunting continues unchecked. Poverty, population increase, unemployment and the weak enforcement of existing wildlife laws are the driving forces behind the unsustainable harvest of wildlife resources at the Banyang-Mbo wildlife Sanctuary.
Ghana is far from attaining energy security status. The energy mix in Ghana comprises; traditional biomass (66.7%), crude oil/petroleum products (26.2%), and electricity (7.1%) mainly from large hydro plants. The existing energy insecurity dilemma, where demand for energy services is desperately needed for sustainable development leaves Ghana with no other option than to exploit its renewable energy resources. The study seeks to address three main research questions namely: (a) Are Renewable Energy Technologies (RETs) technically and economically viable in Ghana?; (b) Can RE projects be self sustained in Ghana without continual external support?; (c) Can RETs be used as an engine for local development? Both qualitative and quantitative methods were employed in analyzing the issues raised. The four main RE resources identified in Ghana are biomass, solar, small hydro and wind energy. Detailed case study analysis for each resource was done for identification of technically and economically viable options. The study concludes with a strategy on the where, what, why and how to implement viable RE projects in Ghana and a ‘best policy’ recommendation for successful market diffusion of RETs. It proposes that RETs must be provided in forms that match the basic and economic self-reliance needs of the people and generated electricity should be tied directly to viable end-use activities.
Rural electrification has been one of the challenges faced by the government of Ghana due to extremely high cost of electricity extension to the rural areas. In order to meet up this challenge, the government of Ghana has been keen with the introduction of renewable energy programs as a solution for rural electrification. However, most of programs are also faced with the problem of being sustainable. After government and sponsors hand-over completed project to local users, they usually last only few years of their life span and are abandoned. This challenge has inspired this study to identify the potential barriers to the sustainability of rural electrification programs through technical and socio-economic evaluation of a solar PV rural electrification project in Ghana.
The approach of this study selected an on-going solar PV project (community solar system-CSS), that has been introduced on a pilot base across the whole of Ghana, which is to be adopted as a standard system for electrification solutions in rural areas in Ghana. This project was subjected to both technical and socio-economic evaluations covering 13 rural communities across the southern part of the country. Stakeholder interviews and review of literature were additional methodologies employed to gather information pertinent to the theme of the study.
The results of the study show that technically, the CSS project has simple design and operational technologies, which gives it high integration potential. However, the project faces the problem of technology misuse by the rural users and frequent failure of its components. The socio-economic barriers identified are: (1) ineffective management of the project due to a long chain of bureaucratic administrative management system, inadequate monitoring and supervision, and inconsistency in standardizing the cash flow of the project, and (2) low electricity capacity of the CSS project and other similar small scale renewable projects to meet the electricity requirements of the rural populates. These problems lead to gradual decline of users’ interest for such small scale renewable energy projects and subsequently result in project abandonment. It was concluded that small scale renewable energy programs lack the capacity to fully meet the energy requirement of rural populates; however, they are crucial as intervening solutions and play key role in rural development.
In order to integrate necessary interdisciplinary complexity, sustainability, defined targets and endpoints for reclamation progress, the objective of this research is to advance reclamation knowledge on (i) international scale and (ii) national scale, taking Nigeria as an example. On the international scale (i), a systematic reclamation threshold scale for assessing, evaluating, documenting, and monitoring reclamation progress was developed. The threshold stages begin from the initial state I0 down to degraded state D0 (depending on the type of mining). Reclamation starts with soil reconstruction R-2 up to revegetation R-1 (red zones) to reach minimum threshold R0 (amber zone). Beyond R0 are the green zones R1, R2, and R3 representing soil/abiotic condition, biological and improved threshold respectively. Adaptation of the threshold model to degraded ecosystems in national and international laws is recommended. On the national scale with Nigeria (ii), endowed with over 34 solid minerals and abundant crude oil, findings show that almost all mine sites are below the minimum threshold scale R0. The sites are adversely affected by Artisanal and Small Scale Mining (ASM), whereby, contamination and soil lithology disturbances are the state-of-the-art discussions. However, bioremediation (phytoremediation) is the most feasible remediation technique. Therefore, for the crude oil contaminated sites, this study highlights typical cogitation for large in-situ implementation and potential species for remediation. For the mineral resources, gold mining was the typical example. As a practical approach, experimental areas on an abandoned mining site (Site 1), an active mining site (Site 2) and an undisturbed vegetation site (Control) in southwestern Nigeria were mapped out to represent its mining and farming activities. On the sites, (a) the impacts of the ASM activities on the floristic association were assessed. (b) the potential of 2D Electrical Resistivity Tomography (ERT) was explored to characterize the horizontal and vertical landscape homogeneity of the mine sites, and lastly, (c) the study identified native high-accumulating plants growing on the sites that can be employed for phytoremediation. Thus, the results show that (a) the floristic association of the mine sites have been stressed and disturbed. (b) the resistivity structure of the sites shows that ASM has greatly impaired the lithological status of the sites. (c) out of the 9 considered species, Crinum jagus has the highest accumulation factor of 8.71, 37.47, 1.08 and 29.38 for Pb, Cd, Fe and Cu respectively. It is a recommendable novel plant in the tropics. However, future studies must verify its hyperaccumulator potentials, identify other high accumulating species and develop effective approaches and policies to curb ASM activities and enhance remediation in Nigeria.
Being one of Ukraine’s major sources of economic revenue, the country’s agro-industrial sector proved, at the same time, to be perhaps the most vulnerable branch of economy in the times of political and social turbulence. While the state is searching for the ways of strengthening its positions at the global market, its agricultural potential to a considerable extent remains both under- and misused. Based on comprehensive historic analysis, this research establishes the origins of the current situation and assesses the possibilities of positive change. Utilizing the experience of other European countries’ with regards to making agriculture more sustainable and competitive in the modern world, the author describes the ways of applying these practices against the background of Ukrainian socio-political system. Drawing knowledge from the experience of Strategic Environmental Assessment (SEA) worldwide, this research aims at harmonizing their methods with evaluation demands in Ukrainian agriculture. It discusses and criticizes the existing assessment approach and suggests measures necessary for making it more comprehensive. The author offers profound analysis of Ukrainian agricultural policies to date, reviews national regulating directives and outlines country-specific challenges as to improving agricultural sustainability. In order to provide Ukrainian decision-makers with a clear and all-round tool for assessing the advances and failures of the acting state policies in the AIS, a set of reliable indices for evaluating agricultural performance has been developed by the author, which is largely based on the widely-acknowledged Driving Force – State – Response framework offered by the Organization of Economic Cooperation and Development (OECD) and Human Development Index (HDI) from United Nations Development Programme (UNDP) methodology. At the same time, the newly developed set takes into consideration the peculiarities of Ukrainian socio-political setting. Three major categories of indicators were chosen as a backbone for further elaboration, namely economic, social and political. Therefrom results a list of twelve relevant indices. At the concluding stage of the research, they were processed and transformed to three top-level indices: Economic Development Index, Environmental Situation Index and Social Development Index. These three indices are intended for clear and illustrative presentation of the current situation for high level decision-makers and governmental bodies. Methodology utilized for the purposes of this research with necessary adaptation and fine tuning can also be used with other set of initial data, indicators and indices. Application field can also be downscaled from the highest (national) to the lowest (regional) level by adapting the indicator-indices system to the initial input data. This will considerably simplify the compilation and presentation of regional reports and will provide transparency for interregional comparison within the country.
Owing to its unique strategic position on the northern coast of the Black Sea, Crimea has, since Antiquity, been a highly diverse, multi-ethnic, multi-religious location. Throughout history, the peninsula’s landscapes were shaped and transformed under the influence of its ever-changing populations. In this process, religion played a crucial role. Nowadays, Crimea abounds in sacred sites in the same way as it abounds in culturally and religiously diverse inhabitants.
Rebirth in the 1990s of the religious and cultural life that had been repressed for over seventy years of the Soviet rule gave a powerful impetus to the revival of Crimea’s sacred landscapes and enabled the different ethno-religious groups residing in the peninsula to re-establish the bond with the home of their ancestors. The notion of landscape as a memoryscape became central in this context, since it is the landscape that records, as well as reflects, the events in history. The sites communally regarded as sacred unite the people as much as common memories transmitted from one generation to the other do.
The objectives of the theoretical part of this thesis are twofold. On the one hand, it aims to grasp the connection between religion, landscape and memory, whereby sacred sites are seen as landscapes of memory and anchors of people’s cultural and religious identity. On the other hand, it seeks to explore the specific issues pertinent to the Crimean socio-cultural context, such as the peninsula’s history and the evolving ethno-religious relationships among the diverse local population, which have impacted the development and protection of Crimea’s sacred sites overtime. Method employed is the comparative literature review, whereby for each chapter a selection of authors was made, whose contributions towards the discussion of the aforementioned issues have been particularly relevant.
Based on the theoretical background described above, the empirical section of the research targets two main groups of actors: the state on the one side, and the organizations representing local religious groups on the other. In relation to the state, the objective is to explore how the religious revival of the post-Soviet period correlates with Ukraine’s current policies towards the safeguarding of Crimea’s sacred landscapes, namely, to what extent they are being protected under the existing legislation, and which of the aspects are given most attention in the process. In relation to the organizations representing local religious groups, the task is to investigate to what degree the sacred sites under study remain relevant for various groups, and to establish how the knowledge about the local sacred places and their importance is being disseminated both within these groups and beyond.
In order to fulfill these tasks, the set of indicators has been developed, which takes into consideration the specific Crimean socio-cultural context, and a selection of case studies has been made, which in their totality reflect the viewpoints of Crimea’s prominent religious groups. The case studies are: (1) the Assumption Monastery, (2) the cave town of Chufut Kale with Balta Tiymez Karaite cemetery, and (3) the old town of Bakhchisaray with Salachiq historic district and Gazy Mansur cemetery. All of the three case studies are located on the territory of Bakhchisaray Historical and Cultural Preserve (BHCP).
The evaluation of the Ukrainian state’s policies with regards to safeguarding of the selected sacred sites revealed that while many of their elements are recognized as cultural heritage of high significance, protection activities are impeded by substantial obstacles of administrative nature, as well as by the lack general planning. Moreover, conservation and day-to-day management is carried out with little consideration for the opinions of the local people and with the insufficient involvement of the latter.
The indicator-based assessment of relevance of the selected sacred locations for various local religious groups and the ways, in which the knowledge about these sites is being spread exposed a number of clear tendencies, as well as highlighted the existing challenges and deficiencies which need to be urgently addressed, so as to ensure the safeguarding of the studied sites for the future generations.
A computational tool and a methodology for steady state heat exchanger simulations of recuperated gas turbines and aero-engines have been developed. As an example a compact tube bundle heat exchanger with oval shaped tubes was chosen. The simulation tool proved to work for different layouts of the heat exchanger and for different geometrical configurations of the gas turbine engine exhaust ducts. The resistance tensors were tuned against both CFD-data and experimental data and the computational model was to some extent validated against experimental results. For the validation isothermal experimental data from the Laboratory of Fluid Mechanics and Turbomachinery at the Technical University of Thessaloniki was used together with hot gas channel data from MTU. The calculated and measured velocity profiles showed an acceptable agreement that in some of the cases was even very good. The calculated pressure drop deviated less than 10% for the compared cases, which must be considered to be acceptable. The calculared results for the hot gas cases showed an exaggerated heat transfer rate, most likely due to the use of a cold side heat transfer correlation for fully turbulent flow, although the Reynolds numbersindicated transitional flow.
Städte bilden Schnittpunkte in translokalen Güterflüssen und Versorgungssystemen. Insbesondere die Versorgung der Stadtbevölkerung mit Lebensmitteln ist – wie die Wasser- oder Energieversorgung – eine Grundvoraussetzung für das Funktionieren städtischer Lebensweisen. Sie prägt die Beziehungen von Städten zu ihrem Hinterland. In der Geschichte bildete die ständige Expansion der Landwirtschaft und der Mittel des Warentransports eine wesentliche Bedingung für städtisches Wachstum, und heute hat die Lebensmittelversorgung längst eine planetarische Dimension angenommen. Ihre Formen und Abläufe, wie auch die Rituale des Essens, haben sich seit Jahrhunderten in die Architektur der Städte eingeschrieben. Dennoch bleiben die Strukturen der Lebensmittelversorgung meist unter dem Radar der Stadtforschung und -planung.
Im Seminar „Feeding the City“ haben wir uns mit den Lieferketten konventioneller Lebensmittel befasst, wie wir sie im Supermarkt oder Discounter in großer Zahl und zu niedrigen Preisen kaufen können: abgepacktes Fabrikbrot, H-Milch, Hähnchenbrust, Bananen oder Fruchtgummis. Wo kommen sie her, welchen Weg nehmen sie und wie formen sie die Räume, durch die sie zirkulieren? Welche Akteur*innen und Regularien bestimmen diese Vorgänge und Zusammenhänge? Studierende der Stadtplanung und Architektur der BTU Cottbus-Senftenberg haben zehn alltägliche Lebensmittel verfolgt: Vom Ort ihres Anbaus oder der Tierhaltung über die Stationen der Lebensmittelindustrie und Distribution bis hin zum Einzelhandel, dem privaten Kühlschrank oder Esstisch und zur Entsorgung der Überbleibsel. Anhand von Kartierungen und Netzwerkdiagrammen haben sie die räumliche Reichweite und die Komplexität der Lieferketten betrachtet, sie haben die gebauten Räume einzelner Stationen und ihre städtischen Kontexte analysiert und schließlich nach der aktuellen oder historischen Präsenz des jeweiligen Produkts in der Stadt Cottbus gefragt.
Due to the unique electronic band structure, graphene has opened the great potential to extend the functionality of a large variety of graphene-based devices in health and environment, energy storage, or various microelectronic applications, to mention a few. At this point, the implementation of graphene into Silicon (Si) semiconductor technology is strongly dependent on several key challenges. Among them, high-quality and wafer-scale graphene synthesis on CMOS compatible substrates is of the highest importance. Though large-area graphene can be achieved on substrates like copper, platinum, silicon carbide, or single-crystal Ni, however, high growth temperatures, unavailability of large scale, or contamination issues are the main drawbacks of their usage. In this PhD work, 8-inch scale graphene synthesis is attempted on alternative substrates such as epitaxial Germanium on Si and polycrystalline Nickel on Si. To achieve the growth of the highest quality of graphene, this work focuses on the investigations of various nucleation and growth mechanisms, substrate–graphene interfaces, effects of different substrate orientations, and detailed microscopic and macroscopic characterization of the grown films. Finally, it should also be stressed that the experiments in this work were carried out in a standard BiCMOS pilot-line, making this study unique, as its results might directly pave the way to further graphene integration and graphene-based device prototyping in mainstream Si technologies.
Yemen is one of the most water-stressed countries in the world. The water deficit has been aggravated by the rapidly increasing demands for both surface and groundwater resources that are being unsustainably exploited. To address the country’s severe water scarcity, the government has adopted long-term intervention policies as stated in ‘Yemen's Strategic Vision 2025’. These policies are aimed at restoring the balance between water demand and availability, and at reducing the existing water deficit. Although 11 years have passed since this vision was adopted, the water deficit is still on the rise. The present situation raises questions about the efficiency of the intervention policies adopted by ‘Yemen's Strategic Vision 2025’ and about the effectiveness of implementing these policies. Another fundamental question pertains to the availability of a strategic assessment tool in the water resources sector that can be used to assess strategically future and current policies, strategies and plans, in order to ensure their efficiency in supporting water resources and in producing the positive impacts for which these strategic initiatives were developed in the first place. Strategic Environmental Assessment (SEA) is an assessment tool designed to function at a strategic level and help to bring aspects of environmental sustainability into the decisionmaking process. This research aims to demonstrate the potential of SEA in enhancing environmental sustainability in water policies for achieving sustainability of water resources in Yemen. In order to show the potential of SEA in the Yemeni water resources sector, this research has applied SEA methodologies and adopted a scenario-building approach for assessing the intervention policies adopted by ‘Yemen's Strategic Vision 2025’ to support augmentation of water resources. Qualitative and quantitative approaches have been used in this research. Quantitative historical data on water availability, water demand and water savings by interventions have been collected from the databases of national institutions and international organizations concerned. Statistical analyses have been used to project future trends until 2025. Qualitative analyses of relevant studies and reports covering the environmental, administrative, sociocultural and political-economic aspects of water resources management in Yemen have been implemented as well. In addition, 13 semi-structured key informant interviews have been conducted with decision-makers, managers and leading experts in the water and irrigation sectors. The research produced three future scenarios for the total water balance that may play out until 2025 in Yemen. These scenarios provide impact assessment and alternatives’ comparison of the existing intervention policies. The resulting scenarios are as follows: the ‘Business as Usual’ scenario, which forms an assessment of currently applied interventions and provides an image for the future, if current interventions are maintained at the same pace; the ‘Do-nothing’ scenario representing the situation if no interventions are implemented; and the ‘Sustainability’ scenario, which represents the potential future of the total water balance if existing interventions are to be scaled up and out. The findings confirm the significant potential of currently adopted intervention policies to support water resources. They also reveal that the current level of implementing the intervention policies has hindered the potential of these intervention policies in achieving the expected positive impact on the water balance by 2025. In order to achieve a significant decrease in the water deficit, the strategic quantitative targets that need to be implemented were identified. The methodology followed in implementing the research and achieving the findings demonstrates the potential of SEA in enhancing environmental sustainability in water policies for achieving integrated and sustainable water resources management in Yemen. The recommendations of the research covered improving the existing water balance as well as improving the assessment and planning context in the water resources sector. In order to improve the water balance situation, the research recommends implementing quantitative targets for water savings and augmentations, such as those developed by this research. These targets have been identified based on the capacities of sectors implementing these interventions. The research also recommends further decentralization of planning and management of water resources and the establishment of Water User Associations (WUAs) as the main vehicles for ensuring sustainable planning and management of water resources, including the scale out of interventions, subject to assessment in this research. In order to improve assessment and planning of water resources, the research recommends the adoption of SEA, the updating of water resources data and conducting regular assessments of policies, plans and programmes as part of monitoring their impact and providing a chance for amending these policies and strategies, if required, to achieve sustainability of water resources.
The old city core experienced a long series of modernization process that affected the old urban fabric and the coherence among urban elements. This dissertation tried to explore the intervention methods and the variety of impacts that have been occurred inside the old core . New streets that were added to the city changed the urban space hierarchy in each time. Starting from analyzing the spatial form via exploring the morphology of the city up to analyze the city skyline is the main methodology of this work. The spatial form of the city of Baghdad shows the impacts of multi planning approaches belong to variant master plans which were proposed and achieved to manage the city growth and development. Those impacts were varied and explained in this dissertation based on the change in the city network, city expansion and land use distribution. The old city of Baghdad was analyzed and explained in details in term of investigating the morphological layers for different periods showing the development of Baghdad urban structure by new comparative plans that explain the change between two following morphological periods. The understanding of the transformation in each morphological period was based on the following criteria’s (urban growth, urban space development, urban components and innovations) to provide a comprehensive investigation about the behavior of the urban components. The investigation of the main old and new streets was well assessed showing their structure, building typologies and the role of the urban space typologies along the segments of those streets. The transect analysis method was used by having nine sections through the old city in different areas to understand the transformation in the city of Baghdad and the impacts of the unregulated development process accompanied within the lack of clear urban management method. The development of the city skyline provided a clear interpretation about the impacts of inserting new urban space and building typologies inside the old core. It was so clear that the hypothesis of this dissertation was proved in showing the role of the street hierarchy change (for both pedestrian and car street in different segments) in exploring the mechanism of the conflict among urban components that bring more destruction to the city. The conclusion showed what to avoid in any prospective rehabilitation process and gave the impacts of the previous interventions that shoud not be repeated in the future.
Interpretation and presentation of Nabataeans innovative technologies: case study Petra/Jordan
(2011)
The Nabataeans were people of innovation and technology. Many clear evidences were left behind them that prove this fact. Unfortunately for a site like Petra, visited by crowds of visitors and tourists every day, many major elements need to be strengthened in terms of interpretation and presentation techniques in order to reflect the unique and genuine aspects of the place. The major elements that need to be changed include: un-authorized tour guides, insufficient interpretation site information in terms of quality and display. In spite of Jordan‘s numerous archaeological sites (especially Petra) within the international standards, legislations and conventions that discuss intensively interpretation and presentation guidelines for archaeological site in a country like Jordan, it is not easy to implement these standards in Petra at present for several reasons which include: presence of different stakeholders, lack of funding, local community. Moreover, many interpretation and development plans were previously made for Petra, which makes it harder to determine the starting point. Within the work I did, I proposed two ideas for developing interpretation technique in Petra. First was using the theme technique, which creates a story from the site or from innovations done by the inhabitants, and to be presented to visitors in a modern approach. The purpose of this story is to link the visitor to the site emotionally, by providing them with the sense and feel of the site‘s real events by that time together with a good amount of information that gives the visitor the chance to live and feel an unforgettable experience of the place. The second idea was how to tailor a useful interpretation plan that could be implemented on all other archaeological sites in Jordan right after "evaluating the results of its implementation in Petra". The aim of this thesis is to develop interpretation criteria for "local governments and nongovernmental organizations", as well as an interpretation plan in a Jordanian context and apply them on all other archaeological sites in Jordan. Tourists would benefit from the quality of interpretation services offered by the interpreters and the techniques of presentation available on the site, in addition to tour guides who have received training programs derivate from this study, which would guarantee in return a more sustainable tourism movement to the site of Petra in the future.
Due to the use of fossil fuel resources, many environmental problems have been increasingly growing. Thus, the recent research focuses on the use of environment friendly materials from sustainable feedstocks for future fuels, chemicals, fibers and polymers. Lignocellulosic biomass has become the raw material of choice for these new materials. Recently, the research has focused on using lignin as a substitute material in many industrial applications. The antiradical and antimicrobial activity of lignin and lignin-based films are both of great interest for applications such as food packaging additives. DPPH assay was used to determine the antioxidant activity of Kraft lignin compared to Organosolv lignins from different biomasses. The purification procedure of Kraft lignin showed that double-fold selective extraction is the most efficient confirmed by UV-Vis, FTIR, HSQC, 31PNMR, SEC, and XRD. The antioxidant capacity was discussed regarding the biomass source, pulping process, and degree of purification. Lignin obtained from industrial black liquor are compared with beech wood samples: Biomass source influences the DPPH inhibition (softwood > grass) and the TPC (softwood < grass). DPPH inhibition affected by the polarity of the extraction solvent. Following the trend: ethanol > diethylether > acetone. Reduced polydispersity has positive influence on the DPPH inhibition. Storage decreased the DPPH inhibition but increased the TPC values. The DPPH assay was also used to discuss the antiradical activity of HPMC/lignin and HPMC/lignin/chitosan films. In both binary (HPMC/lignin) and ternary (HPMC/lignin/chitosan) systems the 5% addition showed the highest activity and the highest addition had the lowest. Both scavenging activity and antimicrobial activity are dependent on the biomass source; Organosolv of softwood > Kraft of softwood > Organosolv of grass. Lignins and lignin-containing films showed high antimicrobial activities against Gram-positive and Gram-negative bacteria at 35 °C and at low temperatures (0-7 °C). Purification of Kraft lignin has a negative effect on the antimicrobial activity while storage has positive effect. The lignin leaching in the produced films affected the activity positively and the chitosan addition enhances the activity for both Gram-positive and Gram-negative bacteria. Testing the films against food spoilage bacteria that grow at low temperatures revealed the activity of the 30% addition on HPMC/L1 film against both B. thermosphacta and P. fluorescens while L5 was active only against B. thermosphacta. In HPMC/lignin/chitosan films, the 5% addition exhibited activity against both food spoilage bacteria.
Die Inwertsetzung von kulturellem Erbe ist in den letzten Jahren zu einem wichtigen Faktor für eine ökonomische, materielle, ökologische, aber auch infrastrukturelle Entwicklung von strukturschwachen Regionen geworden. Für eine Inwertsetzung eignet sich insbesondere das immaterielle Erbe der Menschen in solchen Regionen.
Immaterielles Erbe ist ein Erbe, das auch von der UNESCO anerkannt worden ist und als Intangible Heritage seit 2003 sogar durch eine UNESCO-Konvention geschützt wird. Der vorliegende Leitfaden beruht darauf, das Potential zur Inwertsetzung von immateriellem Erbe in der Lausitz zu erschließen und es für eine Regionalentwicklung im weitesten Sinne aufzubereiten. Regionale Akteure sollen dazu motiviert werden, ihr immaterielles Kulturerbe zu entdecken und für individuelle und institutionelle Entwicklungsprozesse zu nutzen.
In the last years, energy prices for German households have been increasing constantly. Some reasons for that include: the dependency of Germany on external fossil fuels to supply its energy demand, the decision to invest in renewable energy generation and to shut down all its nuclear power plants. Nowadays households are already able to generate energy on-site, however the generation potential depends on climatic conditions as well as the specific location and the type of the building. The aim of this work is to evaluate whether a community of new efficient single-family houses can generate enough energy on-site to supply its electricity and heating demand over the year based on renewable energy sources and with the support of energy storage systems, including electric vehicles. The theoretical community is situated in the city of Cottbus, Germany. For this community, an electricity load profile was designed based on the use of common devices and separated in controllable and uncontrollable loads. Electricity is generated on-site through photovoltaic panels and small wind turbines, and the electricity generation potential is evaluated based on the community’s available space, which is rather limited, and the actual regulations in the State of Brandenburg. A comparison of the available technologies to supply the heating demand as well as to store energy in the household sector is presented and discussed. It is assumed that each household has an electric vehicle that can be charged and also discharged in the community as an extra energy storage system. A software simulation system was designed with which an energy balance analysis is carried out based on hourly values of supply and demand. Under the assumptions taken for this study, the results of the simulation show that the community is able to generate more energy than consumed throughout a year, however in a few occasions there is not enough energy available to supply the community’s energy demand. Water can be heated up to 70°C at least once a week preventing the bacterium Legionella to grow. The community is able to supply 99% of the uncontrollable load group demand and 97% of the controllable load group demand. There is enough energy available to heat space during the cold months, if heat pumps with a coefficient of performance greater than two are used. The electric vehicles can be charged using the energy generated in the community via grid or extra battery banks. If energy prices continue to increase, German households will try to find solutions to reduce their energy bills. The integration of several households forming a community network is a solution that optimizes the energy use and space (especially taking wind turbines in consideration), and reduces investments. However, the implementation of such a community still depends on the availability of space, improvement and price reduction of energy storage systems, regulations for energy exchange as well as willingness of the people living in such a community to adapt their daily routine according to the availability of energy.
Human life depends on water of good quality. Freshwater ecosystems are being degraded as a result of anthropogenic activities. Managing freshwater resources require a good understanding of the dynamics of the processes affecting water quality and the interrelationship existing between them. Signal analysis methods are used to extract information from water quality time series. The information obtained from such analysis is required for developing dynamic models as an aid in investigating the outcome of different management scenarios. They are equally useful in determining the appropriate sampling frequency required for monitoring ecological indicators. Modern methods developed in other field such as mathematical statistics need to be investigated in the fields of water quality management so as to enhance the knowledge of the functioning and the structure of water bodies. Classical methods consisting of time domain and frequency domain methods in combination with a modern method, wavelet analysis, were used to extract information from water quality indicators from the River Havel in the State of Brandenburg in Germany. The indicators were dissolved oxygen, chlorophyll-a and water temperature which are respectively chemical, biological and physical indicators. The time domain methods revealed the behavior of the signal across time as well as the relationship between them. The frequency domain methods proved quite inadequate because the signals from water quality are non-stationary with changing variance across time. The wavelet methods were quite good in unraveling the behavior of these signals at different time-scales. This analysis revealed that the high frequency changes have no significant effect on the long term dynamics of water quality signals. Given that only the low frequency components influence the long term behavior of these signals, it was found that it makes more sense to sample most of the signals at a weekly or two weekly intervals so as to avoid noisy or redundant information. In addition, the time-scale decomposition allows for noisy or redundant information that blurs the long term dynamics thereby negatively affecting the quality of models to be detected and kicked out. Moreover, it was also found that the use of a time delay in a dynamic model should be based on the delay from the time-scale that influence the long term dynamics the most in the freshwater body by the help of the wavelet cross-correlation rather than the classical cross-correlation. Finally, the same indicator from different water bodies of the same watershed portrayed different time and frequency dependent behavior implying that each freshwater body needs to be uniquely investigated. Applying the same management techniques to different water bodies without prior investigation will not be sound. Freshwater ecosystems are more and more threatened by phenomena such as global warming, pharmaceuticals in water bodies, invasive species requiring more investigation on the applicability of tools developed in other fields of science in the field of water resource management. Enhanced knowledge will improve the existing knowledge on the structure and functioning of freshwater bodies, the quality of models developed as management decision aid and the quality of the data used for decision making.
This dissertation closely examines industrial pollution along the Atlantic coast of Cameroon. In recent years, there has been the formulation of both governmental initiatives and corporate voluntary practices with the view of curbing industrial pollution along the coast of Cameroon. However, a majority of studies have failed to ascertain the extent to which these initiates and practices have been successful in addressing industrial pollution, which is undoubtedly fundamental to policy makers in the decision making process. Therefore, this thesis attempts to bridge this major gap by examining both governmental and voluntary corporate practices vis-à-vis industrial pollution along the polluted coast of Cameroon. The thesis analysis efforts formulated by the government of Cameroon to mitigate industrial pollution. It identifies constraints to Environmental Impact Assessment (EIA) practice in Cameroon. Environmental management system (EMS) initiatives adopted by industries along the coast of Cameroon that has been hitherto ignored is unveiled as well in this thesis. Furthermore, a more compelling case is made by addressing the drivers, benefits and barriers stemming from EMS implementation by these industries. A robust reflexive methodological research strategy is developed and utilized both qualitative and quantitative data collected from unstructured interviews, questionnaire based surveys, personal observations, relevant literature, consultancy reports and documentation form governmental departments. Analysis of these data facilitates detailed discussion of both governmental initiatives and corporate environmental management systems.The thesis contends that there is an urgent need to complement governmental policy and regulations with corporate voluntary environmental management systems. It purports that efforts made by the government of Cameroon to address industrial pollution have had minimal impacts on industrial pollution along the coast of Cameroon and submits that the EMS process in these industries is still at its infancy. Moreover, it is argued that a plethora of barriers still prevail that deter a rigorous implementation of EMS in these industries. On the basis of this, the thesis advances a comprehensive strategy for the effective and efficient management of industrial pollution along the coast of Cameroon and emphasizes that a holistic or concerted approach from all stakeholders is absolutely mandatory for the successful implementation of the recommended strategies.
The contribution of community involvement in heritage management : a cultural mapping project
(2023)
Heritage has been lately the matter of debate regarding its definition, conservation and management approaches. In the last few years, there has been an increasing demand for the involvement of the local community in heritage management. Too often, the involvement perspectives of key stakeholders in general and the community members, in particular, are entirely different. While the theoretical ground of community involvement is somehow well set, heritage management has been slow in applying the involvement approach. Practically, it is not easy to find the balance to achieve all the goals of key stakeholders in any involvement project. Subsequently, there are a few numbers of empirical works on the practical implications of understanding heritage management effective tools and limited indication to convince recent ‘power-holders’ such as governmental organizations to distribute their power with local community members.
This doctoral research project explores community involvement in heritage management as an effective solution to building a strong management system. The study aims to examine the level and the quality of involvement in the management of heritage sites in general through a cultural mapping-based approach. This is applied to a case study which is the Religious Complex in Historic Cairo World Heritage Site. The research outcomes indicate the importance of involving the local community in heritage management and planning processes. Ultimately, the study provides critical empirical evidence and draws valuable theoretical and practical assumptions that spread knowledge of cultural mapping in critical issues, such as the drivers of involvement and cooperative decision-making.
Die hier vorgelegte Studie über die Akzeptanz einer modernisierten Variante der ehemaligen „DDR-Gemeindeschwester“ im Land Brandenburg – eben jener Community (Health) Nurse, wie sie international längst etabliert ist – nutzt methodisch eine Diskursanalyse, die interessante Ergebnisse zur Diskussion stellt. Die Befunde lassen sich plausibel in einer Art „Mentalitätsraum“ abbilden. Im Achsenkreuz einer „Strategieachse“ (mit den Kontrastpolen „strategisch-ökonomisch“ vs. „kulturell-kommunikativ“) und einer „Modernisierungsachse“ (mit den Gegensatzpaaren „traditionell-sozial“ vs. „modern-funktional“) kann die Studie vier Diskursvarianten positionieren, die der Einrichtung einer gegenüber dem Prinzip der caring community verpflichteten Pflege mehr oder weniger aufgeschlossen sind: die Argumentationsfiguren „Reformdiskurs“, „Reformpraxis“, „lokale Verankerung“ und „professionelle Enge“. Das zunächst positive Resultat, dass der Kern der Argumentationen in einer „Meinungswolke“ liegt, die vom linken unteren Quadranten bis zum rechten oberen Quadranten des Mentalitätsraums reicht und ihren Schwerpunkt zwischen den Polen „kulturell-kommunikativ“ und „modern-funktional“ (also im linken oberen Quadranten) hat, wird durch zwei Beobachtungen relativiert: (a) verweisen nicht alle der auf den ersten Blick „fortschrittlichen“ Argumentationsfiguren auf praktische Veränderungen; (b) bleibt die Argumentationsfigur „professionelle Enge“, die sich vor allem auf den pflegepolitisch so wichtigen Bereich der ambulanten Pflegedienste bezieht, im Datenmaterial unterrepräsentiert und muss für die zukünftige Entwicklung besonders ernst genommen werden. Auf diese Fragen weist die Studie jedoch mit besonderem Nachdruck hin und verbindet ihre Ergebnisse mit sinnvollen pragmatischen Forschungsdesideraten für die Zukunft der Gesundheitspolitik im Land Brandenburg.
The role of AJB35136 and fdtA genes in biofilm formation by avian pathogenic Escherichia coli
(2023)
Background Infections caused by avian pathogenic Escherichia coli (APEC) result in significant economic losses in poultry industry. APEC strains are known to form biofilms in various conditions allowing them to thrive even under harsh and nutrient-deficient conditions on different surfaces, and this ability enables them to evade chemical and biological eradication methods. Despite knowing the whole genome sequences of various APEC isolates, little has been reported regarding their biofilm-associated genes. A random transposon mutant library of the wild-type APEC IMT 5155 comprising 1,300 mutants was analyzed for biofilm formation under nutrient deprived conditions using Videoscan technology coupled with fluorescence microscopy. Seven transposon mutants were found to have reproducibly and significantly altered biofilm formation and their mutated genes were identified by arbitrary PCR and DNA sequencing. The intact genes were acquired from the wild-type strain, cloned in pACYC177 plasmid and transformed into the respective altered biofilm forming transposon mutants, and the biofilm formation was checked in comparison to the wild type and mutant strains under the same conditions.
Results In this study, we report seven genes i.e., nhaA, fdeC, yjhB, lysU, ecpR, AJB35136 and fdtA of APEC with significant contribution to biofilm formation. Reintroduction of AJB35136 and fdtA, reversed the altered phenotype proving that a significant role being played by these two O-antigen related genes in APEC biofilm formation. Presence of these seven genes across nonpathogenic E. coli and APEC genomes was also analyzed showing that they are more prevalent in the latter.
Additive technologies are now widely used for the production of complex precise parts and have high potential for the production of forming dies. In this work, hot-forming dies optimized for additive manufacturing were developed and produced with wire arc direct energy deposition (WA-DED) and laser powder bed fusion (L-PBF) technologies. The concept of lightweight hot-forming dies with a 2D-lattice structure was developed, which reduced the weight of each die by 56%, from 14.2 kg to 6.1 kg, in production using L-PBF. Maraging/precipitation-hardened steel 17-4PH was used as an alternative to traditional hot-working steels with slightly lower mechanical properties and a much higher processability in the additive manufacturing process. The workability of the manufactured dies was confirmed by forging tests on an industrial screw press.
Das Ergebnis der vorliegenden Arbeit sind grafische Bemessungshilfen in Form von Interaktionsdiagrammen für Stahlbetondruckglieder mit zweiachsiger Biegung. Bei der Anwendung der Diagramme wird die bisherige Einschränkung auf den ebenen Fall aufgehoben. Es stellt sich somit der ebene Fall lediglich als Sonderfall des räumlichen Zustandes dar. Grundlage für das verwendete Rechenverfahren nach Theorie II. Ordnung ist eine von der Ebene auf den Raum erweiterte Modellstütze. Diese virtuelle Kragstütze mit gleichen oder unterschiedlichen Ersatzlängen in den beiden Achsrichtungen dient als statisches System, an welchem alle Berechnungen durchgeführt werden. Es zeigte sich, dass die Verwendung der Betonarbeitslinie die ursprünglich nur für die Querschnittsbemessung vorgesehen ist, auch bei Anwendung in der Traglastberechnung zu einer guten Übereinstimmung zwischen rechnerischen und experimentellen Ergebnissen führt. Die Mitwirkung des Betons auf Zug zwischen den Rissen ("Tension-stiffening"-Effekt) sollte beim Tragfähigkeitsnachweis nicht angesetzt werden, da dadurch die Traglasten teilweise erheblich überschätzt werden.
Mathematically, cryptographic approaches are secure. This means that the time an attacker needs for finding the secret by brute forcing these approaches is about the time of the existence of our world. Practically, an algorithm implemented in hardware is a device that generates a lot of additional data during the calculation process. Its power consumption, electromagnetic radiation, etc. can be measured, saved and analysed for key extraction. Such attacks are called side channel analysis attacks and are significant threats when applying cryptographic algorithms. By considering these attacks when implementing a cryptographic algorithm, it is possible to design an implementation that is more resistant against them.
The goal of this thesis was to design a methodology to securely implement the Montgomery kP-operation using an IHP implementation as a starting point. In addition, the area and energy consumption of the secure Montgomery kP-multiplier should still be highly efficient. The resistance against power analysis attacks of two different IHP ECC implementations was analysed in this thesis. A horizontal power analysis attack using the difference-of-means test was performed with the goal of finding potential leakage sources exploited in side channel analysis attacks, i.e. finding the reasons of a correct extraction of the cryptographic key. For both analysed ECC designs, four key candidates were extracted with a correctness of 90% or more. Through analysis of the implemented Montgomery kP-algorithm’s functionality and its power consumption, it was established that the algorithm’s operation execution flow was the main cause of the implementations’ vulnerability. Thus, a design methodology consisting in changing the Montgomery kP-algorithm operation flow was developed. As a result, the re-designed implementations do not deliver any correctly extracted key candidates whenever the difference-of-means test is performed on them. These re-designs implied an increase on the chip area by about 5% for each implementation. The execution time needed for performing a complete kP-operation was reduced for both designs. Thereby one implementation’s execution time was reduced by 12% in comparison to its original version and even though its power consumption was increased by 9%, its energy consumption per kP-operation was reduced by 4.5%.
Programmable Logic Controllers (PLCs) are pivotal in Critical Infrastructures (CIs) and Industrial Control Systems (ICSs), governing processes in nuclear power plants, petrochemical factories, and water treatment systems. Despite their importance, PLCs are vulnerable to security threats, notably control logic injection attacks, aiming to sabotage physical processes. This thesis delves into PLC security, analyzing vulnerabilities in non-cryptographically and cryptographically protected PLCs, particularly Siemens S7-300 and S7-1500 models.
Siemens, an automation market leader, utilizes S7-300 PLCs in millions of applications, reflecting the broader ICS security landscape. The S7-1500 line claims resistance to cyberattacks, including control logic injections. The thesis evaluates authentication in non-cryptographically protected PLCs, introducing a stealthy control logic injection attack scenario using an S7-300 PLC and S7Comm protocol.
The second part explores integrity checks in cryptographically protected S7-1500 PLCs. Findings, encompassing disclosed vulnerabilities, lead to a severe control logic injection attack with a malicious interrupt block, conducted in an industrial setting using the S7-1500 and S7CommPlus protocol.
The final segment focuses on Profinet protocol security and an injection attack scenario. The study demonstrates adversaries manipulating critical data without prior knowledge, causing harm to physical processes. A real-world attack on a Profinet-based system with two S7-300 PLCs is executed.
The thesis concludes by proposing mitigation solutions, enhancing PLC and communication protocol security. This contribution elevates the security posture of millions of operating devices globally, advancing PLC security research.
In dieser Arbeit werden Ansätze zur Softwareentwicklung auf Objektorientierter Basis im Bereich der Kosten in Hochbauprojekten beschrieben. Die Konzepte der Objektorientierten Technologie zur Softwareentwicklung werden in dieser Arbeit umfassend eingesetzt. Zur Modellierung des Systems wird die Unified Modeling Language (UML) eingesetzt. Die bedeutenden Gesichtspunkte dieser Modellierung sind die Entwicklung des Objektmodells in der Analysephase und deren Verfeinerung in der Entwurfsphase. Dieses Objektmodell bildet die Basis bei der Softwareentwicklung im bereich der Kosten in Hochbauprojekten. Im Rahmen dieser Modellierung werden auch die Aspekte der Soft- und Hardwareverteilung spezifiziert. Ferner werden Konzepte zur Implementierung der Ergebnisse der Modellierung erläutert. Hier wird das Objektmodell des Systems in die Programmiersprache Java übersetzt.
A cellular approach to optimize the integration of renewable generation into distribution networks
(2022)
The steady growth of the renewable-based technologies in the last twenty years has changed the character of the power systems significantly. Until today, there are more than 112 GW installed photovoltaic and wind parks in Germany and around 90% of the installed renewable generators are integrated into distribution networks. As a result, distribution networks are often facing congestion problems and more investments are needed for the required network development plans.
The political decisions in Germany for increasing the share of renewables in electricity consumption up to 65% until 2030 and the nuclear phase out until 2022 and further shutdowns of the coal power plants raised serious concerns about the reliability of power supply and feasibility of the transition plan.
The present dissertation has a look over the recent developments and offers a methodology for reduction of the resulted costs from further integration of renewable generators into the distribution networks. The suggested methodology is based on a cellular approach and helps also to postpone the unnecessary costly network expansions. Furthermore, it helps to integrate the renewable generators in an optimized way which has an added value to move towards the defined sustainability goals.
The proposed methodology has two steps. The first step is made up of the cellular approach and grey wolf optimization in MATLAB environment. In this step, the optimal combination of technologies for fulfillment of the defined goals are found out. The second step consists of the quasi dynamic simulations in PowerFactory environment. In this step, the suggested results from MATLAB optimization are investigated in semi-real situations. With the quasidynamic simulations, it is checked whether the results are tolerable from the point of view of network operation and whether it is possible to facilitate the network operation with certain strategies.
The main idea of this paper is to evaluate the performance of the fine resolution CLM model in the state of Brandenburg Germany, create a bias correction method and reanalyze the climate signals of the corrected simulations on projections of the 21st century. The bias correction method is a distribution oriented method and the analysis is mainly focused on the extreme events such as 95 and 5 percentile daily temperatures and 95 percentile daily precipitations in a period of 30 years, but also includes seasonal temperature, daily temperature difference and monthly precipitation to demonstrate the effectiveness of the correction method. The results showed that the correction method was very effective on different variables. After correction, the extreme daily temperature bias was reduced from a cold bias of 1-2K to less than 0.1K. The corrected projection simulations suggested that the extreme temperatures were about to increase both in intensity and in frequency. The extreme precipitation after correction was meant to become more severe and frequent as well.
Energieeffizientes Nährstoffsplitting von flüssigen Wirtschaftsdüngern mittels Membranfiltration
(2017)
Die definierte Selektivität der Membranfiltration kann dazu genutzt werden, einzelne spezifische Gülle-Separationsprobleme in übergeordneten Aufbereitungsklassen zusammenzufassen. Mit dem Ansatz einer gesteuerten Nährstofftrennung bzw. Teilzusammenführung von modifizierten Strömen, und der Zuordnung von spezifischen Aufgaben an die Mischprodukte, werden die Nachteile des Ausgangsrohstoffs reduziert und der Wertstoff Gülle rückstandsfrei nutzbar gemacht. Mit einem Anlagenmodell, bestehend aus einer Hydrotankpresse als Vorfiltration und einer Ultrafiltration als Kernkomponenten, ist es über empirisch ermittelte Betriebsparameter möglich, einen energetisch optimierten und kontinuierlichen Produktionsbetrieb durchzuführen. Als Produkte der dezentralen Aufbereitungsanlage werden ein emissionsreduzierender Flüssigdünger, eine als Brennstoff und als Gärsubstrat geeignete Feststoffphase, sowie das Retentat als aktivierendes Material zur Biogasertragssteigerung gewonnen. Das untersuchte Anlagenmodell ist auf den innerbetrieblichen Einsatz in Milchviehhaltungsbetrieben abgestimmt. Mit der Erarbeitung von stabilen und energetisch günstigen Anlagenbetriebspunkten wird das Anlagenverhalten hydraulisch steuerbar. Durch die Zuordnung von Anlagenzuständen zu differenziertem Spülverhalten, wird die direkte Einflussnahme der Temperatur auf den Permeat-Flux erkennbar. Der Einsatz eines Tauchkühlers, mit voreingestellten Grenztemperaturen, stabilisiert signifikant das Anlagenverhalten im Vergleich zu konventionellen Anlagenkonfigurationen. Die Anwendung einer Hydropresse gestattet höhere TDS-Belastungen im UF-Kreislauf, bietet aber kein Potenzial zur Steigerung der Nährstoffdurchsätze. Dies gilt auch für den Einsatz einer 300 kDa-Variante, im Vergleich zur priorisierten 150 kDa-UF-Membran. Mit der Hydropresse kann eine höhere Feststoffabscheidung wie mit Verstopfungs- bzw. Siebfiltrationen erreicht werden, die TDS-Belastungen sind im Retentat auf 5.000 - 7.000 ppm limitiert, oder müssen durch Verdünnung auf diese Werte eingegrenzt werden. Mit der zusätzlichen Anwendung einer Gasspülung in der Anströmung der UF-Module, können TDS-Belastungen über 10.000 ppm erstmals dauerhaft bewältigt werden. Über die so erweiterte Verfahrenstechnik sind Standzeiten von mehreren Wochen, ohne betrieblich bedingte Unterbrechungen, möglich. Die durch Fluoreszenzmikroskopie nachweisbare Anreicherung von Methanbildnern im Retentat, bestätigt eine mögliche Anwendung des Retentats als Biogassubstratergänzung. Der Biogasertrag wird durch Zusatz von Retentat zu den bisher verfügbaren Substraten generell erhöht. Eine Mischung aus Retentat und dem Feststoff aus der Hydropresse unterstützen die biochemische Stabilisierung in Fermentern. In Kombination mit Anteilen an Feststoff ist das Permeat bei der Bewertung von pflanzenbaulichen Erträgen, als konkurrenzfähig zu Rohgülle und Mineralstoffdünger einzustufen. Das auf landwirtschaftliche Flächen ausgebrachte Permeat ist geruchslos.
Brain-computer interfacing (BCI) is a relatively new field of study that involves engineering, neuroscience, psychology, and physiology. A BCI is a system that allows direct communication between the brain and the environment, using signals from electroencephalography (EEG) to identify a user's intentions and mental states. This can be used for human-machine interaction (HMI) to adapt software or control a device. Particularly passive BCIs are the most promising for the general population, as they can detect and interpret a user's mental state without requiring their attention. This can enable neuroadaptive technology (NAT), which allows a machine to learn over time how the user perceives and interprets the world. However, there are still obstacles to be overcome before BCI technology can be applied in real-world situations for NAT.
In this work I firstly address the issue of subject dependence in training data collection for classifier calibration, which can be time-consuming and impractical. I investigated the training of a subject-independent predictive model that is trained on a group of other users' data and applied to online-testing data of a new person. This was done in the context of training an automatic classifier for error detection and correction. Results showed that a classifier model can be trained without user-specific calibration and with high accuracy. The number of electrodes used in training the model was also reduced. Further it was validated that the trained classifier models were based on cortical sources and not other modalities.
In a second study I address the issue of task-dependence. To that end I tested the application of a potentially task-independent calibration paradigm for mental workload assessment in a new task. This new task was a speed reading context, where subjects read texts of varying difficulty and speed. The study found that the mental workload prediction model was accurate in classifying mental workload in different reading tasks, indicating that it can be used as a task-independent classifier for mental workload.
In a third study I examine if it is possible to measure neural correlates of human moral assessment using a passive BCI on a single-trial basis. A calibration paradigm was developed using pictures that were ranked as morally unacceptable and morally neutral. However, the results showed low classification accuracies and it was not possible to reliably distinguish between a user's subjective moral evaluations on a single-trial basis using current classification approaches.
The results presented in this thesis provide solutions towards real-world applicability of NAT enabled by passive BCIs, as examples of a subject-independent and a task-independent classifier are demonstrated and discussed. Further, approaches for increased versatility of passive BCI technology are presented, that could make passive BCIs more feasible for use in future real-world human-machine interaction settings.
Untersuchung und Optimierung robuster und hochlinearer rauscharmer Verstärker in GaN-Technologie
(2018)
Die nächste Generation von integrierten Sende- und Empfangsystemen erfordert sowohl robuste rauscharme Verstärker als auch Leistungsverstärker auf einem einzelnen Chip. Die GaN-HEMT-Technologie hat bisher gezeigt, dass sie durch ihre hohen Durchbruchspannungen, die hohe Elektronenbeweglichkeit und die niedrige Rauschzahl ein guter Kandidat für die Realisierung solcher Systeme ist.
Diese Arbeit beschäftigt sich mit hochlinearen und robusten rauscharmen Verstärkern, welche in Sender-Empfänger-Systeme integriert werden können. Zuerst wird der GaN HEMT charakterisiert. Die Eigenschaften von Transistoren werden während des Burn-in Prozesses und gepulster Anregung mit hoher Überlast am Eingang analysiert. Damit werden die Grundlagen für das Verständnis des Verhaltens eines Verstärkers während und nach der Übersteuerung am Eingang gelegt.
Der Hauptteil dieser Arbeit zeigt die Entwicklung und die Charakterisierung von robusten rauscharmen Verstärkern. Darüber hinaus wird ein neues Konzept für die Steigerung der Robustheit entwickelt, gemessen und charakterisiert.
Das Konzept verwendet eine neuartige Zusammenschaltung zweier
Transistoren am Verstärkereingang, wodurch die Spannungsfestigkeit gegenüber hohen Leistungspegeln gesteigert wird. Damit konnten Höchstwerte von +44dBm mit CW-Anregung und +47dBm mit gepulster Anregung am Verstärkereingang ohne Beschädigung demonstriert werden.
The representation of Brazil in American mainstream cinema disseminates stereotypes that have their roots in narratives produced by European explorers during the colonial era. Films and other media from Brazil portray the country’s cultural and ethnic diversity more accurately, but due to media concentration and the global supremacy of the US-based film and television industry, only a few manage to reach international audiences and challenge widespread stereotypes. A critical examination of writings of Portuguese explorers produced in the centuries following the arrival of Pedro Álvares Cabral in Brazil provides the basis for the analysis of contemporary representations of Brazil in American cinema and reveals how early descriptions of Brazil have influenced these representations. In order to identify the main Brazilian stereotypes disseminated by feature films produced in the United States, a number of films released between 1984 and 2011 are analyzed. The results of the analysis allow for the identification of an ethnocentric regime of representation that is often employed by the world’s leading film and television industry to portray Otherness, reinforcing stereotypical ideas about racial difference and the culture and people of developing countries. The analysis is followed by a discussion of cultural imperialism, media concentration and its impact on cultural diversity and media pluralism. The investigation of the concentrated ownership of media, which raises concerns regarding cultural homogenization, the advancement of corporate interests over the public interest and loss of cultural diversity, indicates how media concentration contributes to the perpetuation of cultural, ethnic and national stereotypes that reinforce colonialist and reductionist ideas about developing countries. The results of the film analysis, combined with issues related to the increasing concentration of media ownership, confirm the proposition to revive the debate about a New World Information and Communication Order (NWICO), which emerged within UNESCO in the 1970s as a reaction of Third World nations to colonialism and the economic and cultural influence of Western nations. Finally, it is argued that, despite the failure of NWICO in the past, the concept has not lost relevance and it would be reasonable to bring it back to the international agenda.
Primary and secondary data were collected during the period of January – May 2005 and questionnaires were issued between August – December 2004 to know the Status of Wildlife and its Utilisation in Faro and Benoué National Parks North Cameroon: Case study of the Derby Eland (Taurotragus derbianus gigas Gray, 1947) and the African Wild Dog (Lycaon pictus Temminck, 1840). The line transect method was used to assess wildlife population. Geographical Information System (GIS) maps of Faro and Benoué National Parks were drawn to show their distribution. Eleven different wildlife species were studied in Faro and Benoué National park. The density of Kobus kob in Faro was 0.39 animals/km² and 0.28 animals/km² in Benoué and that for Acelaphus buselaphus was 0.4 animals/km² in Benoué National park. The encounter rate was calculated for all other species and it was weak in Faro ranging from 0.009 – 0.01 while in Benoué it was higher ranging from 0.03 – 0.87. The highest encounter rate was from Benoué National Park for Loxodonta africanna. The total biomass for wildlife was 13,224.4 kg/km² with the higest percentage contribution of which 60.49% coming from Taurotragus derbianus gigas in Faro National Park.The total biomass in Benoué National Park was 37, 1839 kg/km² with the biomass for Taurotragus derbianus gigas as 20 kg/km² and percentage contribution of 9.68%. The higest percentage contribution to the total biomass in Benoué National Park was 85.52% coming from Loxodonta Africana. No observations or trace of the Lycaon pictus was seen in the two parks (Faro and Benoué) within the study period. Removal and replacement rates of Taurotragus derbianus gigas showed a polynomial shaped curve with periods of population increase and decrease with regards to yearly behaviour while the previewed Lycaon pictus for hunting showed a polynomial shaped curve while its actual removal dwindled on a straight line. Removal and replacement is not influenced by sport hunting activities alone but prey availability, absence and presence of predators, disease, car accidents and other human influences. However, the critical value for the exploitation (sport hunting) of wildlife over a period of 20 years in Faro and Benoué National Parks was necessary to be determined though it was a difficult attempt. Income generated from park activities had doubled from 42.8 million F CFA to 92.5 million F CFA in 2001. Categories of hunters coming to the parks for hunting activities were 90% non-residents, 6% residents and 4% nationals hunting by permit. The estimated annual revenue from wildlife was 91,185.00 Euros and 773,685.00 Euros in Faro and Benoué National Parks respectively. Taurotragus derbianus gigas had the highest value of 19,400 Euros in Faro National Park and 87,000 Euros in Benoué National Park. Both parks contribute 0.58% of the total revenue generated by wildlife in Faro and Benoué. There was a high level of awareness about conservation of the Taurotragus derbianus gigas and the Lycaon pictus. Also was a general willingness to pay for the conservation of resources though it was an issue of a social dilemma of choosing between self interest and collective gains. However, the population was willing to pay 500 F CFA to generate a conservation fund to sustain identified conservation projects. Assessing the management policy of the government, 40% of the population wish to be compensated for giving away their resource while 28% opt for exchange, 9% expropriation, 16% continuation and 1% had indicated no option (neutral).
Im Rahmen dieser Arbeit wurden die Zündungseigenschaften einer neuartigen Brennkammer untersucht, wobei auch das Magerverlöschverhalten mit in Betracht gezogen wurde. Die Untersuchungen der Zündbarkeit basieren auf den Ergebnissen numerischer Simulationen und anschließenden Auswertungen in einer Zündsubroutine. Die Ergebnisse der Strömungssimulationen sind mit PIV-Messungen experimentell validiert worden, wobei die simulierten Sprayformen durch die ermittelten Mie-Aufnahmen bestätigt wurden. Hochgeschwindigkeitskamera - Aufnahmen wurden zur Validierung der berechneten minimalen Zündenergien verwendet. Die vorgenommenen Korrelationen zwischen den kalkulierten Werten der minimalen Zündenergie sowie den gemessenen AFR-Zündungsdaten eröffnen einen Weg zur Bestimmung der zu erwartenden zündbaren Gemischkonzentrationen in realen Brennkammern aufgrund der simulierten minimalen Zündenergie. Im Rahmen der Arbeit wurde weiterhin eine Parametergewichtung durchgeführt, welche als Grundlage bei der Optimierung ähnlicher Brennkammern dienen kann.
Human influence on the biosphere has transformed natural land cover (LC) into modified LC. Shifting focus from individual species study to large-scale assessment is therefore needed to restore the damaged ecosystem. The hypotheses were: (a) the post-mining landscapes are getting more diverse over time (b) GIS, remote sensing and patch analyst can generate LC information and landscape characterization statistics for assessing habitat diversity and monitoring land cover change (LCC) in a disturbance-dominated area (c) relationship exist between habitat diversity and field based species richness/LCC and environmental conditions/LCC and biodiversity losses. The general aims of this research were (a) to assess the impact of disturbance on LCC and habitat diversity (b) to identify how accurately patterns of habitat diversity, complexity, fragmentation, primary production and LCC can be assessed or predicted with GIS and remotely sensed data. LC maps of 1988, 1991, 1995, 1998, 2000 and 2003 were produced from LANDSAT TM images of Schlabendorf Nord and Schlabendorf Süd. These images were used to survey the changing landscape. After classifying the images based on dominant land cover types, the area and perimeter of all patches were defined. Landscape characterization metrics were generated using patch analyst. LCC statistics were estimated for each LC map year. Change detection extension was used to identify changes among vegetation or land cover types into “negative change”, “no change” and “positive change”. DCA ordination technique (CANOCO) was used to study similarity among the distribution of land cover types. Other relevant analysis made include soil pH analysis and climate data evaluation. The outcome of the research shows that the process of LCC takes place at the interface between environmental and human systems. Land cover transformations in most cases in Schlabendorf were as a result of progressive and reversed plant succession. Overall changes in both landscapes showed increased area of pine afforestation, deciduous trees afforestation, lake and mixed grassland with trees. The LCC s were predominantly caused by harvesting of afforested pine, restoration related construction activities or other land cover management practices, reverse succession, low soil pH especially along the path of the mine strip, loss of soil fertility, human decisions and policies. There was increase in habitat richness, heterogeneity, fragmentation, and shape complexity due to decrease in habitat size, increased land use intensity etc. Lower habitat diversity in Schlabendorf Süd was due to the comparatively large landscape area, high patch number and higher habitat richness in most cases which confirms the claim that relationship between habitat diversity and habitat heterogeneity varies according to scale (Tews et al., 2004). Increase in biomass accumulation particularly in Schlabendorf Süd contributed to the exchanges for greenhouse gases between the forest cover, soil and the atmosphere, hence changing the climatic condition on terrestrial ecosystems, biodiversity and LCC. Unlike Schlabendorf Nord, Schlabendorf Süd still undergoes more active reclamation activities resulting in less similarity between the two post-mining landscapes over time. Within a given ecosystem, any change in habitat diversity can change the number of species in the resulting habitats types, in other words habitat diversity can be used to predict the species richness in a given ecosystem. The approach to this work provides a beneficial trade off between expensive ground vegetation or LCC survey and low-priced image processing analysis. It requires less manpower and less time but greatly reliable for assessing LCC, habitat diversity/richness and heterogeneity in large inaccessible areas such as dunes in post-mining landscape.
Wastewater treatment systems abound as a result of technological improvements in treatment processes. Therefore in the selection of a wastewater treatment system for a particular wastewater treatment situation there are many alternatives to choose from. Despite this development municipal wastewater treatment in communities in developing countries are not always sustainable due to the application of inappropriate treatment systems. The question is how can an appropriate treatment system be identified for a certain location? The answer to this question is of importance to developing countries where wastewater treatment is usually not sustainable.
In this study a framework for assessing wastewater treatment systems was developed. First, a comprehensive set of indicators representing parameters of treatment systems and properties of the study area that impacts on wastewater treatment were identified. Secondly, assessment of these indicators were carried out through expert and community survey to identify a final set of indicators whose composition consist of efficiency, reliability and simplicity of treatment systems and resource constraint, resource recovery and environmental concerns of the study area. Thirdly, four wastewater treatment systems, namely: Waste Stabilization Ponds, Trickling Filter, reed bed and free water surface Constructed Wetlands considered to be feasible for the study area were evaluated by the application of the identified indicators. Finally, a decision matrix produced was processed by multi-attribute decision making methods using two indicator weights to identify the most appropriate treatment system among the four alternatives.
Results of the study show that in a scenario where equal indicator weights are assumed, reed bed is identified as the most appropriate with stabilization ponds being ranked as the least appropriate. In a more practical scenario where the weights of the indicators are allocated to reflect conditions of the study area, free water surface is ranked as the most appropriate. This outcome is at variance with stabilization pond technologies currently installed at communities in the study area. The performance of constructed wetlands is at the midpoint as far as most of the high to medium weighted assessment indicators are concern. It therefore represents a compromising solution between waste stabilization pond and trickling filter. The study also shows a change in variants of constructed wetland with a change in indicator weights. An indication that the decision situation determines the appropriateness of a treatment system and not the treatment system itself.
The selection framework employed in this study can be said to be reliable and capable of identifying a treatment system that can be appropriate for a particular location. This is because the choice of a constructed wetland for the study area fits the definition of appropriate treatment system defined by the final indicators identified in this study.
The design of high Q oscillators, using Crystals at lower frequencies, (and dielectric resonators at much higher frequencies), has long been considered a black art. This may be due to the fact that a systematic approach with optimized design guideline for crystal oscillators could not be found after extensive literature search.
In this dissertation, after analyzing the first crystal oscillator by W.G. Cady (1921), other high performance crystal oscillators will be discussed, analyzed and calculated.
A single transistor crystal oscillator design as used by HP (Hewlett Packard) in one of their designs, the HP10811A is considered in this thesis for mathematical analysis and CAD (Computer aided Design) simulation. This was also measured on state-of-the-art signal source analyzer. After validation, this design is scaled to 100MHz, the frequency of interest for this dissertation.
Though most designers use a single transistor based oscillator circuit, it is not an optimized design because of limited control over key design parameters such as loop gain, dc current etc.
This dissertation is an attempt to overcome the limitation due to the single transistor circuit and to give a step by step procedure, explaining the significance of a two transistor design with thorough analysis and design simulation results. This two stage transistor circuit is also not yet a best solution in terms of phase noise performance and output power, and some add-on circuitry will be needed for an optimized performance.
An important contribution of this work is to show that since the voltage gain is the ratio of the collector resistor and the emitter resistor, the performance is practically independent of the VHF transistor and gives better control over various parameters of the oscillator, in order to optimize the design.
A grounded-base amplifier is then introduced and added for improving the isolation and the output power. Unlike most oscillators, that take the output from the collector, a novel concept introduced by Rohde [14], is incorporated here, where the crystal is used as a filter that is then connected to the grounded base amplifier, a technique which many companies have been using. This dissertation will show that this technique increases the output power without significantly affecting the phase noise. Such a validation is needed for better understanding and as per my knowledge, has not been done so far.
For the oscillator, the tuning diode sensitivity and flicker noise contribution are also taken into consideration, by calibrating the mathematics and its validation is shown.
Crystal resonators of the type AT and stress-compensated (SC) cut devices will be considered as they give the best performance. The one port Colpitts type oscillator is considered first and the two port two transistor design later. Both will need a post amplifier/buffer stage.
A complete step by step design procedure for an optimized 100MHz crystal oscillator is then presented.
For completeness, CAD Simulation and Experimental results are provided for 10 MHz, 128 MHz and 155 MHz VCO circuits.
This thesis addresses the electro-optical properties of silicon, containing dislocations. The interest in those properties is driven mainly by two practical reasons. One is the optical characterisation of multicrystalline silicon for solar cells, and the other is the design of light emitting diodes based on silicon by enhancement of silicon radiative properties via introduction of dislocations. The work demonstrates that dislocation specific radiation may provide a means for optical diagnostics of solar cell grade silicon. It provides insight into the mechanisms governing the dislocation recombination activity, their radiation, and how are they influenced by other defects present in silicon. We demonstrate that photoluminescence mapping is useful for monitoring the recombination activity in solar cell grade silicon and can be applied for identification of contaminants, based on their photoluminescence signatures. It is shown that the recombination at dislocations is strongly influenced by the presence of metals at the dislocation sites. The dislocation radiation activity correlates with their electrical activity. Thus, photoluminescence mapping at room temperature may provide a means for revealing and characterising of dislocation-rich regions in multicrystalline silicon. It is shown that the dislocation and band-to-band luminescence are essentially anti-correlated. The band-to-band intensity being related to the diffusion length of minority carriers can be used for measurements of diffusion length, as long as the surface recombination rate is controlled. Moreover, photoluminescence mapping can be used for the detection of optically active defects in solar grade materials. Thus, betaFeSi2 precipitates, with a luminescence at 0.8 eV, were detected within the grains of block cast materials. They exhibit a characteristic feature of quantum dots, namely blinking. The second aspect of the thesis concerns the topic of silicon based light emitters for on-chip optical interconnects. The goal is an enhancement of sub-band-gap or band-to-band radiation by controlled formation of dislocation-rich areas in microelectronics-grade silicon as well as understanding of the processes governing such enhancement. For light emitters based on band-to-band emission it is shown, that internal quantum efficiency of nearly 2 % can be achieved, but the emission is essentially generated in the bulk of the wafer. On the other hand, light emitters utilizing the emission from dislocation-rich areas of a well localized wafer depth were explored. Three different methods for reproducible formation of a dislocation-rich region beneath the wafer surface were investigated and evaluated in view of their room temperature sub-band-gap radiation: (1) silicon implantation and annealing, (2) epitaxially grown SiGe buffer, and (3) direct wafer bonding. The most promising dislocation-based emitter appears the utilization of a dislocation network produced by wafer bonding. It is shown, that monochromatic D1 radiation (wavelength 1.5 µm) can be generated in a well localised depth of the wafer. The radiation is not absorbed in silicon and such localized emitter can, potentially, be coupled with silicon waveguides and Ge-based detectors for optical interconnects.
Groundwater is an important resource in Sub-Saharan Africa to supply water for domestic, industrial, mining and irrigation for agricultural purposes. In Ghana, groundwater supply program is mostly pragmatic to give people drinking water, however to ensure sustainability a long term groundwater management system is essential. One such approach is the use source protection (well protection) with the declaration and installation of protection zones. To achieve the goal of this research three hypothetical questions were asked which relates to the Availability and Vulnerability of groundwater, and the use of an analytical model to estimate source protection zones (SPZ). The regions of Adansi, Lawra, Sunyani and Sekyere West were chosen as study areas to test the hypothesis of this research with detailed investigation concentrating on Adansi area. The overall aim from the study areas was to estimate SPZ for Granite, Phyllite, Schist, Sandstone and weathered materials and give recommendations as to which activity should be permitted or otherwise within each of these zones. The available groundwater for a particular well or location was determined based on its hydraulic conductivity and specific capacity of a well. Regionalization of the available groundwater was achieved by comparing the results of the hydraulic conductivity and specific capacity with the regional structural map. To determine the vulnerability of the available groundwater, the radius of influence (ROI) for the different boreholes was determined using Sichard and Dupuits formula whilst for Source protection zones, Darcy and the volumetric equation was used. Results of hydraulic conductivity estimated from pumping test data for the five major rock types showed a trimodal distribution (E-5, E-6 and E-7 m/s). There was a general trend of decreasing hydraulic conductivity to decreasing transmissivity. Results of plots of specific capacity verses hydraulic conductivity shows that only rock types with hydraulic conductivity greater than E-5 m/s yields sustainable groundwater supply. Three aquifer types were encountered in the study areas which were pore aquifers in shallow or alluvial, regolith and fracture aquifers in bedrocks. High hydraulic conductivity from the different rock types corresponds to higher ROI. The results of hydraulic conductivity, specific capacity, ROI and SPZ are used as input parameters for the estimation of the suitability of a groundwater source. A ranking matrix was developed for easy interpretation of hydrogeological data by combining the results of the input parameters into a single score. Results from the ranking matrix were used to determine specific regulations for the various aquifers in the study areas. Within the fractured crystalline rocks with k ≥E-5m/s siting of wells should target fracture zones whilst pumping during abstraction phase can exceed 15m3/s/m. The intermediate source protection zone should be at least 150m. Conclusions from the study could be applied in other areas of Ghana and be implemented during the initial development, abstraction and groundwater policy phases of other groundwater projects.
In 2012 a group of researchers proposed a basic research initiative to the German Research Foundation (DFG) as a special priority project (SPP) with the name: Wireless 100 Gbps and beyond. The main goal of this initiative was the investigation of architectures, technologies and methods to go well beyond the state of the art. The target of 100 Gbps was set far away from the (at that time) achievable 1 Gbps such that it was not possible to achieve promising results just by tuning some parameters. We wanted to find breakthrough solutions. When we started the work on the proposal we discussed the challenges to be addressed in order to advancing the wireless communication speed significantly. Having the fundamental Shannon boundary in mind we discussed how to achieve the 100 Gbps speed.
In bubbling fluidized beds, bubble characteristics such as size, shape and velocity have a vital influence on the hydrodynamics of the bed and hence on its performance as a chemical reactor and/or a heat exchange unit. In many industrial applications such as lignite dryer heat transfer tubes are usually inserted to enhance the rate of heat and mass transfer and chemical conversion. However, their presence strongly influences the bubbling behavior of the beds. Therefore, reliable design and scale-up of these systems come only after fundamental understanding of the bubbling behavior is achieved. Therefore, in this research work the influences of tube bank geometries and particle size on bubble characteristics were thoroughly investigated. In this research work, both numerical and experimental studies were employed. For the experimental measurements, a new nonintrusive digital image analysis technique was developed. The technique allowed for the simultaneous measurements of bed expansion and various bubble properties. An in-house software was developed to fully automate the image acquisition and data processing procedure. For the numerical studies, the Eulerian-Eulerian two-fluid model based on the kinetic theory of granular flow was used. Though, this CFD model has been considered as a fundamental tool for modeling gas-solid fluidized beds, its quantitative validation remains insufficient for a wide range of reactor geometries and operating conditions. Therefore, in this work validation of the model using experimental measurements of bed expansion and bubble properties obtained from a pseudo-two-dimensional fluidized bed was performed. The influence of two-dimensional simulations and different modeling parameters such as the friction packing limit, drag model and solid-wall boundary conditions were investigated. The two-fluid model generally showed reasonable agreement with the experimental measurements of pressure drop, bed expansion and bubble properties in bubbling regime. However, as the gas superficial velocity is increased and the bed moved towards slugging and turbulent regimes a big deviation arose and the two-fluid model failed to predict reasonably the fluidized bed hydrodynamics for the freely bubbling bed. The mean bubble properties predicted by two-dimensional simulations were in reasonable agreement with experiments at lower superficial velocities. They deviated at higher bed height and this was more pronounced at higher gas superficial velocities. The results from three-dimensional simulations were in better agreement with the experimental measurements; however, the computational effort need was very high making them impractical for parametric studies and sensitivity analyses. It was also showed that the choice of friction packing limits, drag laws and specularity coefficients have little influence on the bubble properties. For a bubbling bed, both experimental measurements and numerical simulations showed that inserting horizontal tube banks had either no or marginal influence on the static bed pressure drop and bed expansion. On the other hand, bubble hydrodynamics were strongly influenced and controlled by the geometry of the immersed tubes. In freely bubbling fluidized beds bubble size as well as rise velocity increased with bed height and superficial velocity. In beds with immersed tubes, such general trends were completely disturbed. Tubes appeared to restrict rapidly growing bubbles. As a result the mean bubble diameter and rise velocity were lower in the vicinity of the tube banks than in the freely bubbling bed. Results from different particle sizes showed that in a freely bubbling bed increasing the mean particle size increased the bubble diameter and rise velocity as well as bed expansion. In fluidized beds with dense horizontal tubes on the other hand, the mean bubble properties were almost independent of the particle sizes.
As the issue of pollutant emissions from aviation propulsion escalates, research into alternative powertrains is gaining momentum. Two promising technologies are the Hybrid Electric Propulsion System (HEPS) and Pressure Gain Combustion (PGC). HEPS is expected to reduce pollutant emissions by decreasing fuel consumption, whereas PGC uses detonation in the combustor to increase the thermal efficiency of engines by elevating the total pressure during combustion. This study extensively explores the integration of these two emerging technologies, thoroughly assessing the advantages that arise from their combination. First, the renowned turboprop engine PW127 is benchmarked and modeled using Gasturb software. The model is integrated into Simulink using the T-MATS tool, with HEPS and pressure gain components added to analyze the thermodynamics of various configurations under different pressure gain values and HEPS parameters. The analysis, conducted up to the cruise phase of the baseline aircraft, reveals that applying pressure gain combustion through Rotating Detonation Combustion (RDC) results in a more significant increase in efficiency and decrease in fuel consumption compared to HEPS with conventional gas turbines. However, HEPS helps maintain a more uniform combustor inlet condition and reduces the Turbine Inlet Temperature (TIT) at the takeoff phase, where the highest TIT otherwise occurs. The results suggest that integrating HEPS with PGC can be beneficial in maintaining optimal combustor conditions and mitigating turbine efficiency degradation.
Recycling and material recovery are gaining more grounds in applicability as viable options to sustainable solid waste management especially in Municipal Solid Waste Management (MSWM) schemes. In this dissertation a critical analyzes is made of the MSWM problem in Cameroon and an assessment of the role Small- and Medium-Size Enterprises have been playing in the area of recycling and material recovery. The main research methods applied in this research include: fieldwork, administration of questionnaires, interview and literature review. Using two case study localities (Limbe and Buea municipalities), the various practices in MSWM are elaborated, the constraints and challenges faced by management discussed and proposals for either expanding/upgrading existing schemes to be more sustainable as well as strategies to initiate new systems presented. Innovations within collection systems such as the introduction of household bins and specialized collection of specific waste could be quite beneficial to existing schemes. Waste Electrical and Electronic Equipment (WEEE) which constitute one of the fastest growing waste streams presents greater management challenges. Two case study localities (Buea and Kumba) are used to analyze the problem of WEEE in Cameroon. An overview of the handling of Electrical and Electronic Equipment (EEE) at end-of-life (EoL) in Cameroon is made with special focus on households and repair units. At household level, WEEE is disposed of alongside other waste arisings in the available disposal facilities for given household. Repair units represent a very vital connection between dysfunctional EEE and EoL forms as all users of EEE tend to bring these devices to these units for repairs. An inventory of the various EEE at repair units for these two localities shows that above 40% percent of such equipments are totally out of use. In Kumba, Classes 1 and 4 EEE (according to EU WEEE directive classification) dominate while class 3 is almost absent. In Buea, Class 3 and 4 are dominant. These results show that socio-cultural, economic and even climatic factors influence the choice of EEE that people in this area acquire. The intense level of repair activities and recovery of useful parts by repair units show that there exist adaptable options to handle WEEE in especially economically and environmentally beneficial ways. The recycling of aluminum for production of household utensils represents a very basic and adaptive industrial set-up, which can easily be operated and run at very cheap cost and with a little manpower. While this venture seems apparently successful in economic terms as an option to poverty alleviation through income generation, it is plagued by some problems which, if given due consideration will render it a prospective option for poverty alleviation (through small enterprise business development) and environmental sustainability (as an option to sustainable MSWM). In this dissertation, a model is thus presented, which can be utilized by stakeholders to improve on the sector. An assessment of efforts and constraints to implementing comprehensive recycling and recovery schemes in Cameroon was also carried out. Results show that there are existing practices on which comprehensive recycling and recovery can be built upon that would be beneficial to both councils and engaged schemes – mostly SMEs and NGOs. The challenges faced and likely to be faced and the way forward to implementing any broad scale recovery and recycling are presented. If municipal councils choose to operate existing MSWM schemes without significant changes, then collective collaboration will be highly required. Such collaboration will present benefits to both waste collection and disposal. On the other hand, if they wish to expand schemes or create new schemes, adaptive innovation would be highly recommended. Such adaptive innovation would have to incorporate local practices and approaches of MSWM as well as socio-economic considerations so as to ensure new or expanded schemes survive within local socio-economic context. A greater challenge in enhancing recycling and material recovery in particular and MSWM in general, in Cameroon is on the role the government takes on designing appropriate policies and legislative frameworks to cover such activities in economically and ecological beneficial ways. In the absence of these, SMEs, councils and NGOs (working in partnership with other specialized groups) concerned with activities related to recycling and material recovery may be left with the option of regulating activities within their sectors as such activities stand to alleviate poverty and also present ecological benefits.
Over the last twenty years, Petri nets have been increasingly adopted for modelling and simulating biological systems, as they offer an intuitive and graphical approach for this purpose. Their usability convenience comes from the fact that they offer many types of elements to describe systems in a qualitative and quantitative way. Coloured Petri nets are particularly useful to model systems with repeated components in a compact fashion. Our tool Snoopy for modelling and simulating Petri nets is one of the most well-known tools supporting a family of related Petri net classes comprising stochastic, continuous and hybrid Petri nets, and covering uncoloured and coloured Petri nets alike. However, kinetic information of a biological system, i.e. kinetic parameters may be uncertain, due to many reasons, e.g. environmental factors. Besides, coloured Petri nets as they were previously supported in Snoopy suffered from some inconsistencies. Due to these inconsistencies, exploring the model behaviour using different sizes (scaleability) was not feasible. Both challenges call for a new and more powerful approach integrating the modelling of uncertainties together with modelling features supporting repeated structures in a compact and scalable way.
This thesis comprises two major contributions: Firstly, we introduce the definition and present the simulation algorithm for both uncoloured and coloured fuzzy Petri nets, by extending the existing quantitative uncoloured and coloured Petri nets in Snoopy. This includes discretising the uncertain kinetic parameters to crisp values by using sampling strategies. Secondly, we harmonise coloured Petri nets in Snoopy with their uncoloured counterparts and we extend the Snoopy’s coloured Petri nets by all the features, which are supported by the coloured abstract net description language - an exchange format of coloured Petri nets in our PetriNuts tool family.
By performing fuzzy simulation, one can obtain two kinds of output: fuzzy bands of each output variable and their corresponding timed-membership functions. Each fuzzy band describes the uncertainties associated with the input, whereas membership functions give more accurate information about the associated uncertainties. The most important features that we obtain by harmonising coloured Petri nets are to develop scaleable models, by defining scaling factors as constants and unifying the usage of coloured Petri nets with the other tools in our PetriNuts tool family.
We deal with a very complex and hard scheduling problem. Several types of products are processed by a heterogeneous resource set, where resources have different operating capabilities and setup times are considered. The processing of the products follows different workflows, allowing also assembly lines. The goal is to process all products in minimum time, i.e., the makespan is to be minimized. Because of the complexity of the problem an exact solver would require too much running time. We propose a compound method where a heuristic is combined with an exact solver. Our proposed heuristic is composed of several phases applying different smart strategies. In order to reduce the computational complexity of the exact approach, we exploit the makespan determined by the heuristic as an upper bound for the time horizon, which has a direct in uence on the instance size used in the exact approach. We demonstrate the efficiency of our combined method on multiple problem classes. With the help of the heuristic the exact solver is able to obtain an optimal solution in a much shorter amount of time.
In dieser Arbeit wird ein neues Konzept für den Entwurf fehlertoleranter digitaler Schaltungen vorgestellt. Die als spezifische Fehlertoleranz bezeichnete Entwurfsmethode erweitert den Stand der Technik um die Möglichkeit, Fehlertoleranz gezielt für gewünschte Ein- und Ausgabezuweisungen einer Schaltung bereitzustellen. Die generell sehr aufwändigen Maßnahmen zur Realisierung von Fehlertoleranz lassen sich so an die tatsächlich vorhandenen Zuverlässigkeitsanforderungen einer gegebenen Anwendung anpassen, was im Vergleich zu herkömmlichen Verfahren zu erheblichen Kosteneinsparungen im Hinblick auf Hardware und Stromverbrauch führt. Die Eingaben einer Schaltung werden dazu mit ihren zugehörigen Ausgaben in kritische und unkritische Signale unterteilt. Für kritische Signale wird das gleiche Maß an Fehlertoleranz bereitgestellt, wie es auch durch das Verfahren der dreifach modularen Redundanz garantiert wird. Unkritische Signale werden nicht fehlertolerant ausgelegt, da das für solche Signale nicht gefordert werden muss. Im Bezug auf kombinatorische Schaltungen wird dieses Grundprinzip auf eine beliebig wählbare Teilmenge aller möglichen Eingaben mit ihren zugehörigen Ausgaben angewendet. Die nicht zu schützenden, unkritischen Signale werden zu Optimierungszwecken genutzt. Genau diese Freiheit im Entwurfsprozess ermöglicht beim Entwurf fehlertoleranter Schaltungen signifikante Kosteneinsparungen, die bislang durch andere Verfahren nicht berücksichtigt wurden. Bei sequentiellen Schaltungen wird das Konzept auf Eingabefolgen und ihre entsprechend zugehörigen Ausgabefolgen abgebildet. Ab einem bestimmten Zustand werden in Schaltungen, die nach diesem Prinzip entworfen wurden, alle als kritisch eingestuften Eingabefolgen fehlertolerant verarbeitet, woraufhin die sequentielle Schaltung entsprechend fehlertolerante Ausgabefolgen liefert. Die Länge der kritischen Eingabefolgen und die Anzahl der Zustände, von denen aus eine fehlertolerante Verarbeitung der Eingaben gefordert wird, ist beliebig wählbar. Neben der Beschreibung des Grundkonzeptes der spezifischen Fehlertoleranz für kombinatorische und sequentielle Schaltungen beinhaltet die Arbeit Erweiterungen, mit denen sich die durch das Verfahren bereitgestellte Fehlertoleranz erhöhen lässt. Es wird zudem erläutert, wie die spezifische Fehlertoleranz ohne besonderen Aufwand mit Hilfe gängiger Werkzeuge im Schaltungsentwurf umgesetzt werden kann. Vom Entwerfer werden dazu keine speziellen Kenntnisse über das eigentliche Verfahren vorausgesetzt. Anhand experimenteller Ergebnisse wird auch gezeigt, welche Einsparungen sich durch die spezifische Fehlertoleranz im Vergleich zu herkömmlichen Verfahren aus diesem Bereich ergeben. Dazu wurden verschiedene Benchmark-Schaltungen mit der spezifischen Fehlertoleranz implementiert und ihre Gesamtflächen den Flächen entsprechender Schaltungen, die nach dem Prinzip der dreifach modularen Redundanz entworfen wurden, gegenübergestellt.
An increase in waste production is inextricably linked to population increase and increasing civilization, and depending on the waste management approach, groundwater could be seriously affected. In Limbe, for example, waste disposal methods (sewage, littering, open dumping and burning) have led to the contamination of groundwater resources. This study aims at assessing the degree to which the Limbe waste sites conform to prescribed standards of waste site location, the extent to which the waste sites compromise or enhance groundwater protection. The study further investigates groundwater management around waste sites; investigating the factors responsible for groundwater contamination from waste sites; evaluating the extent to which past and present municipal solid waste management practices minimise or enhance groundwater contamination and suggesting possible methods (techniques) by which the existing situation can be improved. Seven groundwater samples were collected for laboratory (microbiological and physic-chemical) analyses in Cameroon and Germany. Field visits and observations made were supported by pictures and interviews. The method of waste disposal used in Limbe by LUC (until 2006) and HYSACAM (from 2006) already show negative effects on groundwater. Results of microbial analysis are higher than the standards of Cameroon, WHO and ISI 10500-91. Total Coliform showed values >1000CFU/100ml, E. coli showed up to 346CFU/100ml and others showed up to 159CFU/100ml. These excessively high values imply that water is highly contaminated biologically and so groundwater wells in Limbe are not good for human consumption. Physico-chemical analysis revealed, in most samples, values lower than the prescribed standards. However, NH4+ showed higher values in all samples (0.9mg/L-2.6mg/L). The high level of ammonium could be related to high production of sewage in households. L7 and L1 showed the lowest values, whereas, L6 showed the highest values in almost all microbial and physico-chemical parameters analysed. L6 was most contaminated with high values mostly exceeding the given limits. This dominant wetland area must be evacuated and water highly treated because it is very dangerous for human consumption. Vadose water in Limbe requires serious biological treatment and subsequent groundwater monitoring to minimise hazards. L7 and L1 have characteristics of Basalt and because of low level of contamination can be used as the base for comparison (that is natural water). Water must also be thoroughly treated for NH4 contamination. Waste disposal in Limbe is poorly practised and the site used must be changed. Improved waste management schemes like waste reduction, sorting and treatment are required before final disposal. Landfill construction with emphasis on barrier, leachate and gas collection systems will be most appropriate for waste disposal and in minimising leachate spill, and groundwater and other contamination. Geological and hydrogeological maps and investigations as well as recent climatic data are needed in order to choose an appropriate site for landfill construction. Most of all groundwater monitoring and sewage collection should be a very important consideration in the Limbe Municipality. Household dump sites must be thoroughly cleaned and the public sensitised on the importance of proper waste management to reduce groundwater contamination and its effects on man and the environment.
In this thesis we consider probabilistically checkable proofs (PCPs) in the model of computation working with real and complex numbers as introduced by Blum, Shub and Smale (the BSS model). Starting point of this thesis is the so-called PCP theorem, a major result in complexity theory. Roughly speaking this theorem says that one can check the correctness of certain proofs of mathematical statements with high probability by only looking at small parts of the proof. PCPs have a natural formulation in the BSS model as well. Considering the importance of the PCP theorem it seems natural to ask whether a similar theorem holds in this model also. The PCP theorem in the Turing model has two qualitatively very different proofs. The original proof by Arora et al. uses mostly algebraic techniques. Later another, combinatorial proof was discovered by Dinur.
In this thesis we give two corresponding proofs in the BSS model. Thereby we establish the PCP theorem in the framework of the real numbers as well as in the framework of the complex numbers. The main difficulties occur due to the fact that the structures R and C over which we work are uncountably infinite. For both classical proof techniques partially really new ideas are necessary to apply their structure to the new computational model. Apart from the importance of the PCP theorem it helps to better understand the similarities and differences between both models of computation. We hope that the new ideas we develop may be useful in other contexts as well.
In the quest of finding sustainable solution to solid waste management problems in Ghana, this research formulated as its goal, to mitigate policy constraints to sustainable solid waste management in Ghana. This research goal and objectives were addressed through an empirical study that involved interviews and administration of two sets of questionnaires, one set to members of parliament and the other to members of the general public. The development of questionnaires was influenced by a conceptual policy development model “The Bridge Model of Policy Development”. Administration of questionnaires to members of the general public was accomplished through random sampling within churches and mosques in three cities in Ghana; Accra, Kumasi, and Takoradi. The percentage response for members of the general public was 38.9% and that for members of parliament was 18%. Prioritization of policy options was achieved through “Differentiated Perception Ranking”, a method devised by this research process. The results revealed the relative importance of constraints to sustainable solid waste management in Ghana, the relative difficulty of mitigating constraints, and the relative difficulty of implementing policy options among others. These results were integrated with the principles of sustainability into producing a policy package for sustainable solid waste management in Ghana.
Mixed signal integrated circuits (MSICs) contain both analog and digital circuitry, integrated together on the same die. While this integration brings many benefits, it also gives rise to the issue of substrate noise coupling between the noisy digital circuitry and noise-sensitive analog circuitry. In order to counteract this issue, various substrate noise reduction methodologies had been developed so far. This thesis explores a new approach in substrate noise reduction – using a GALS (globally-synchronous, locally-asynchronous) design strategy for the digital part of a MSIC, in order to reduce the noise generation at its source. GALS architectures consist of several locally synchronous modules (LSMs) which communicate asynchronously to each other. By converting an initially synchronous architecture of digital circuitry into a GALS architecture, simultaneous switching noise generated by this circuitry can be reduced. While GALS had already been used for reducing other types of simultaneous switching noise, this is, to the best of the author’s knowledge, the first attempt to develop a GALS-based methodology for substrate noise reduction. In order to be able to theoretically analyze GALS-based methodologies for substrate noise suppression, corresponding models at high abstraction level for substrate noise generation and substrate noise propagation in lightly doped substrates (which is a type of substrate mostly used for MSICs) have been developed. These models have further been used for developing two new GALS-based substrate noise reduction methodologies: harmonic-balanced plesiochronous GALS partitioning (HB) and harmonic-and-area-based plesiochronous GALS partitioning with power domain separation (HAB). A theoretical analysis has shown that HB can reach substrate noise attenuation of up to 20log(M), where M is the number of LSMs of the resulting GALS system. On the other hand, the attenuation achievable by HAB depends on the distribution of switching current harmonics and area among the partitions, as well as from the substrate itself. For each of the two methodologies, a suitable partitioning procedure for a practical application has been developed; these partitionig procedures have been numerically evaluated in MATLAB. HB has further been embedded within the EMIAS CAD tool, where it has been evaluated on a real design example – a wireless sensor node. A special case of HAB for low frequencies has been applied for developing a test chip called SGE (power domain Separation and Galsification Experiment). The measurements on silicon have proved the applicability of the methodology.
Electrostatic precipitators (ESPs) belong to the most efficient devices for control of particle emissions in the process industry and environmental technologies in general. The operating principle of ESPs, relying on particle precipitation by electrical charging, leads to an enhanced turbulent motion by electrohydrodynamic (EHD) effects within the gaseous working fluid passing through the ESP. This enhanced turbulence is generally considered detrimental to the separation efficiency, because the additional shear forces acting on the collection electrodes promote re-entrainment of already precipitated particles. Further, the enhanced turbulent cross mixing diminishes the transport of charged particles by electric forces directed towards the collection electrodes. In other industrial applications however, many process units that are based on heat or mass transport would benefit from enhanced turbulent mixing. These include heat exchangers for energy recuperation or evaporation and absorption units such as flue gas scrubbers. A combination of these with an ESP possibly allows for versatile new applications in the process industry.
The motivation of this thesis is to study the effects of electrohydrodynamically generated motions onto the turbulent cross mixing within gaseous flows over a wide parameter space including variations in geometry and operating conditions. In order to do so, the influence of EHD effects on the three major transport properties, i.e. thermal energy, mass and momentum, were experimentally investigated. Based on analogies caused by similar transport mechanisms, the experimental results were compared despite different methods being used. In order to help with the comparison a simplified eddy viscosity model is applied.
The study for each transport property was conducted with a different setup of a tube type ESP. These setups include axial and radial pressure drop measurements to quantify the momentum transport, a self-built local heat transfer sensor to determine heat transfer coefficients and a wetted wall-column to study the enhancement of mass transport phenomena. Experiments on momentum and heat transport include a large variation of different geometries and operating variables such as discharge electrode design, tube diameter, flow velocity, as well as magnitude and polarity of operating voltage. In addition, selected measurements with aerosol particles were conducted, to gain additional insights on the effects of EHD induced turbulence generation by particle bound space charge compared to ion bound space charge in clean gas flows.
The results do not only provide transport coefficients for the hands-on application by plant designers, but also feature numerous experimental data that can be used as reference values for ongoing research in the numerical simulation of electrohydrodynamically enhanced flow and therefore significantly increase the available amount of data provided by current literature.
Multidimensional visualization of preferential flow pathways using neutron and x-ray radiation
(2016)
The occurrence of preferential flow of water in soils is rather the rule than the exception particularly in heterogeneous structured soils. The quantitative prediction is difficult because of the spatial as well as temporal variability. One aim of the dissertation was to visualize the soil structure and flow patterns in mine soils using a combination of neutron radiography, neutron tomography and x-ray computed tomography experiments. Both radiation techniques were used to describe preferential pathways as a soil structure with CT and the process of preferential flow of water with NT. For the first time neutron radiation was applied on undisturbed soil cores to visualize water distributions in natural soils on three examples for heterogeneities of different origin.
In a first investigation we used neutron radiography to analyze the moisture distribution in undisturbed slab-type and cylindrical samples of mine soils containing lignitic fragments and inclined soil layers. 2D radiography sequences indicated that flow pathways are highly dependent on the shape, distribution, and internal structure of the lignitic fragments. For 3D experiments, the quantitative analysis of water contents failed due to a pronounced beam hardening effect. The tensiometer data indicated the existence of local non-equilibrium in pressure heads between fragments and matric pore regions.
The objective of the second study was to analyze and visualize the effects of initial soil structure formation at the surface of bare soils in an artificial hydrological catchment that has been left to undirected ecological succession for three years. The three-dimensional (3D) micro-morphology was described using the X-ray computed tomography (CT); two-dimensional (2D) infiltration patterns were obtained from drip infiltration experiments using time-resolved neutron radiography (NT). The analyses of CT data indicate the existence of (i) structural crusts on soil consisting of sandy to loamy sediments and (ii) depositional crusts on sandy sediments. The results of combined observations using CT and NT suggest that the initial soil surface structure alterations of young sandy sediment modify moisture patterns of infiltrating water only slightly.
The aim of the 3rd experiment was to study effect of two ‘ecological engineers’, moss vegetation and beetle larvae on pore structure and infiltration. The soil pore structure was characterized by micro-computed tomography analyses of bare soil, sparse and dense moss-vegetated samples containing a single burrow. Flow patterns of infiltration experiments were visualized using the neutron radiography technique. The results of this study suggest that moss vegetation and burrowing activity of ground beetles strongly control the initial soil development by modification of pore structure and surface water infiltration.
Die vorliegende Arbeit beinhaltet eine Nutzungspotentialbewertung einer Bergbaufolgelandschaft (BFL). Mit Hilfe einer zielorientierten Nutzwertanalyse werden die Potentiale Landschaft, Infrastruktur, Wirtschaft, Arbeitsplätze, Ökologie und Nachfrage bewertet und die Gunstfaktoren des Untersuchungsgebietes (UG) herausgestellt, um mögliche Handlungsvorschläge zu geben. Leitbild des UG ist eine den gegebenen Bedingungen entsprechende nachhaltige Entwicklung einer BFL. Eine einst vom Abbau der Braunkohle lebende Region sucht ein neues Gesicht und Möglichkeiten, die durch den Tagebaubetrieb völlig veränderten Bedingungen der Landschaft, Infrastruktur, Wirtschaft, Arbeitsplätze, Ökologie, Nachfrage neu zu formieren. In einer von der Autorin eigens für diese Untersuchung entworfenen Matrix werden die Bewertungsergebnisse räumlich veranschaulicht. In Kopplung mit der Darstellung der mathematisch strukturierten Ergebnisse im Nachhaltigkeitsdreieck wird verdeutlicht, welche ökonomischen, sozialen und ökologischen Bedingungen im UG zu erwarten sind. Vor allem aus der Darstellung der Ergebnisse in der Matrix ist erkennbar, wo im UG welche Potentialfaktoren besonders günstig sind bzw. welche Kombination voneinander positiv beeinflussender Potentiale wo auftreten. Das UG wird sich nicht gleichmäßig entwickeln. Es wird entsprechend einer Knoten-Achsen-Struktur Entwicklungsschwerpunkte geben. Die Wirtschaft und die sozialen Beziehungen als Wachstumspole werden besonders in den Knoten gefördert. Die Achsen erstrecken sich entlang der infrastrukturellen Erschließung über den Rand des Gebietes hinaus und sorgen für eine Anbindung an das Umland. Das UG besitzt sehr günstige ökologische Potentiale, die bei der weiteren Entwicklung unbedingt berücksichtigt werden sollten. Als wenig günstig stellt sich das Potential der Wirtschaft heraus. Das bedeutet, dass besonders Anstrengungen zur Verbesserung der wirtschaftlichen Basis in diesem Gebiet unternommen werden müssen. Schlechte ökonomische Bedingungen ziehen rasch verschlechternde soziale Verhältnisse nach sich. Das UG befindet sich in einer Region, die von Entleerungstendenzen gekennzeichnet ist. Aus diesem Grund ist es wichtig, eine stabile und vielfältige Wirtschaft zu schaffen. Mit dem Totalausfall der ehemaligen wirtschaftlichen Basis, dem Braunkohlenabbau, müssen hier neue Wege gegangen werden, die zudem das ökologische Potential des UG unterstreichen. So genannte „Leuchttürme“ sollten das Gebiet wirtschaftlich wieder attraktiv machen und der Region eine neue Lebenschance geben. Die Autorin stellt Möglichkeiten der touristischen Nutzung vor und plädiert für die Nutzung alternativer Energien und nachwachsender Rohstoffe. Im UG muss Mut zu neuen Wirtschaftsstrukturen bewiesen werden. Je vielfältiger die neuen Möglichkeiten genutzt werden, desto stabiler wird die wirtschaftliche Basis. Je solider sich die ökonomische Grundlage festigt, desto günstiger wirkt sich das auf die sozialen Bedingungen aus. Die ökologische Gunst sollte von Anfang an bei der Gestaltung der Wirtschaft und der Entwicklung neuer Infrastruktur berücksichtigt werden. Dies wurde nicht zuletzt auch durch die Nachfrage bestätigt. Mögliche Ausgänge der Entwicklung werden in Szenarien beschrieben, in denen absichtlich die gegebenen Bedingungen in einer überspitzen Form weitergedacht werden, um das Wesentliche der möglichen Entwicklung darzustellen. Das Besondere der BFL sollte nicht nur als geschichtliche Erinnerung, sondern als raumprägendes Element erkennbar bleiben.
Physiotherapy for patients with hip and knee osteoarthritis in Germany: a survey of current practice
(2023)
Osteoarthritis (OA) of the hip and the knee is common and leads to pain, stiffness and disability. Clinical practice guidelines (CPG) provide recommendations to assist healthcare professionals in clinical decision-making. Although evidence-based physiotherapy has been shown to be effective in the management OA, a gap between clinical practice and guideline recommendations exists. Little is known about OA management provided by physiotherapists in Germany and whether treatment aligns with CPGs. The objectives of this study were (1) to investigate the current physiotherapy practice in patients with hip and/or knee OA in Germany, (2) to evaluate physiotherapists’ adherence to guideline recommendations and (3) to explore barriers and facilitators to guideline use.
The master thesis at hand examines the potential of district heating in Lusatia. The thesis follows the approach of first identifying technical and economic potentials in general and then transferring them to the study region. For the quantitative determination of district heating potential in Lusatia, the status quo is determined and a GIS-based analysis is carried out with regard to minimum heat demand densities. The extent to which district heating is suitable for climate-neutral heat supply will be investigated using the potential of renewable and waste heat energy sources. Furthermore, the regional economic effects of developing these potentials are examined. The results show that despite an overall decline in heat demand, there is potential to increase the relative share of district heating in Lusatia. In terms of climate neutrality, district heating in Lusatia offers special opportunities. Solar thermal energy and Power-to-Heat are of particular importance due to the rural character of Lusatia and its status as an energy region. From a regional economic perspective, climate-neutral district heating has a positive effect on value added and employment.
Currently more and more researches of high voltage bushings are focused on the requirements for a simple structure, compactness and light-weight. The general operation of SF6 gas-filled bushings (SF6 bushings) is satisfying the requirements, but in the operation and design of SF6 bushings still many improvements may be possible. The minimizing of dimension might enhance the electric field strength (E) on the crucial points of bushings, which may lead to partial discharge, flashover and even break down. Electric field distribution along the surface mainly depends on contour design, besides the effect of contamination. This dissertation mainly describes the optimization of the bushings design by genetic algorithm.
First, a model of SF6 bushing was developed and simulated for the theory purpose. Then, the potential breakdown problems were defined and the mechanisms of the potential breakdown were explained. Afterwards, the dissertation proposes an approach, i.e. genetic algorithm to optimize the contour design of SF6 bushings. The approach improved the execution efficiency by accessing the fitness values of searched solutions during the optimization process. To verify the effectiveness of the genetic algorithm, it has been applied to minimize the electric field strength at the critical positions. Furthermore, the critical points of SF6 bushings were optimized. Several new structures of the ground electrode were proposed and optimized separately by genetic algorithm. A new curve, i.e. cubic spline was applied to the contour of the top flange to avoid the influence of the triple points. By optimization E on the surface of top flange was minimized. The potential distribution on the surface of insulator was optimized by a new structure. By the genetic algorithm the contour of composite weather sheds (WS) was optimized as water-drop form.
In summary, a more uniform potential distribution along the surface of weather sheds and minimal values of electric field strength at critical points can be derived effectively by genetic algorithm. In addition, a smaller dimension of SF6 bushing was obtained in comparison with presently available ones.
Phytoplankton succession and diversity-productivity relation in German and Brazilian shallow lakes
(2012)
Phytoplankton succession linked to productivity-diversity relationship at steady-state/non steady state conditions, mixing events as predominant disturbance in sense of Connell (1978) and influence of conditional differentiation (temperature) on phytoplankton diversity were investigated. Water samples were taken two times a week in 4 German shallow lakes in Brandenbug region (Melangsee, Petersdorfer See, Wolziger See, and Langer See) from 2007 to 2010 and in 2009/2010 during cold and rainy season in a Brazilian coastal lagoon Peri. A comparison between literature data from 4 Brazilian lakes, in order to investigate the influence of temperature on diversity and dynamic of phytoplankton species was also done. The cyanobacterial species dominated all studied lakes and the mixing had a positive effect on the supremacy of this group in tropical lakes. The high biovolume of cyanobacteria contributed to the achievement of steady state conditions in sense of Sommer et al. (1993) during consecutive periods in Petersdorfer See and in Peri lagoon practically during all phases. The monodominance of Cylindrospermopsis raciborskii was observed in warm water, under no stratification regime. Oscillatoriales of group S1 (Reynolds 2002), represented by Limnothrix redekei and Pseudanabaena limnetica, typical in turbid mixed layers and with high nitrogen affinity, were typical in Petersdorfer See. In Melangsee, steady state was observed during colder periods under dominance of Bacillariophyceae and Chrysophyceae. Lower diversity coincided with steady state conditions and higher values of resource use efficiency (RUE), while higher diversity occurred mainly at transitional state during the spring in temperate lakes, supporting the non-equilibrium concept (Hutchinson 1961) at lower RUE values. Higher biovolume occurred mainly during the late summer in temperate lakes under dominance of cyanobacteria, and/or at steady state. Concerning the temporal variation of phytoplankton, the highest peak of species richness preceded the resource use efficiency, suggesting the productivity as consequence of diversity. The richness was much higher in temperate shallow lakes, which were more similar to each other in terms of seasonality, species number and biovolume. A positive correlation between richness and biovolume of temperate lakes was found and the opposite was observed in tropical lakes. The biovolume and richness in tropical lakes were more variable and in temperate lakes presented higher richness at intermediate level of biovolume (annual mean from 10 to 18 mm3/l). Low level of biodiversity allows an ecosystem to function under constant conditions, but a greater biodiversity occurred in fluctuating environments.
Cultural heritage faces many types of threats such as neglect, conflicts, disasters caused by natural and human induced hazards, unplanned infrastructure projects, climate change, etc. Over time, a number of institutions, organisations, programmes and initiatives to address the issues related to heritage at risk through varied modes of interventions such as advocacy work, conservation efforts, funding, awareness-raising regarding particular sites, etc. have emerged. Despite the stimulus and support of the various institutions, organisations and initiatives, diverse threats continue to impact cultural heritage in present times with some factors amplifying more than before, leading to the subsequent damages to or losses of heritage assets. Though reasons for these issues are varied and complex, one of the important factors to look into is the agency of the diverse ‘Heritage at Risk’ programmes or initiatives. ICOMOS being one of the pioneers in this global discourse of threatened heritage, its role is strategically vital. 20 years after ICOMOS’s first attempts to initiate one of the first ‘Heritage at Risk’ programmes, this research is an opportunity to re-examine and analyse the effectiveness of ICOMOS’ ‘Heritage at Risk’ programme within the current organisational/ institutional landscape of initiatives in the field of heritage at risk, that ICOMOS is embedded in. It is also an opportunity to situate the programme within the diverse views of the heritage at risk framework and the continuing shifts in the foundational paradigms of the international discourse on heritage conservation. The purpose of this analysis is to guide programme improvement for optimising efforts in favour of cultural heritage at risk within and/ or beyond ICOMOS and improve their ability to contribute towards - safeguarding heritage at risk, increasing the resilience of cultural heritage and sustainable development.
Lipasen sind esterolytische Enzyme, welche vorzugsweise an Lipid/Wasser Phasengrenzen aktiv sind. Von großer Bedeutung sind diese Biokatalysatoren bei etablierten industriellen Prozessen, wie z.B. in der Nahrungs- und Futtermittelindustrie sowie der Herstellung von Detergenzien oder als Additiv in Waschmitteln. Neue Anwendungsgebiete, wie die Produktion von Feinchemikalien für die Pharma- und Agrarindustrie sowie die Herstellung von Biodiesel stellen Herausforderungen dar. Gerade in den letztgenannten Industriezweigen werden herkömmlichen chemischen Verfahren bevorzugt, da die Herstellungskosten von Enzymen einen großtechnischen Einsatz behindern. Um die Kosten für den Einsatz des Biokatalysators zu minimieren, wurden drei Ansatzpunkte bearbeitet.
Bei der Produktion von Lipasen oder anderen Enzymen durch Mikroorganismen fallen Investitions- und Betriebskosten an. Investitionskosten werden maßgeblich vom Reaktordesign und dessen Größe bestimmt, wobei die Betriebskosten zum Beispiel durch den hohen Einsatz von Energie und Zeit bei der Sterilisation sowie teuren Medienbestandteilen festgesetzt werden. Aus dieser Betrachtung heraus wurde in vorhergehenden Arbeiten ein selektives Kultivierungsverfahren mit minimierter Steriltechnik entwickelt, bei dem die Kosten für die Sterilisation entfallen. Im Rahmen der vorliegenden Arbeit wurde eine Maßstabsvergrößerung auf ein Volumen von 350 l durchgeführt. Die robuste Selektivität des Kultivierungssystems im 100-l- und 350-l-Maßstab wurde in 13 individuellen Läufen über einen Kultivierungszeitraum von acht bis zwölf Tagen mit dem Kompostisolat Phialemonium curvatum AW02 gezeigt. Der Mikroorganismus P. curvatum AW02 sowie dessen extrazelluläre Lipasen wurden partiell charakterisiert. Es zeigte sich, dass P. curvatum AW02 mindestens eine zellwandgebundenen Lipase sekretiert. Weiterhin wurde gezeigt, dass das selektive Kultivierungsverfahren mit minimierter Steriltechnik das alleinige Wachstum weiterer bekannter Mikroorganismen, wie z.B. Aspergillus niger, Botrytis cinerea oder Yarrowia lipolytica begünstigt.
Der zweite Ansatzpunkt zur Kostenminimierung ist die Wiederverwendung sowie Stabilisierung des Enzyms durch Immobilisierung, was intensive Entwicklungsarbeit voraussetzt. So wurde ein in der Handhabung leicht durchführbares Immobilisierungsverfahren entwickelt, das auf der Einbettung wasserfreier Enzympräparate in ein Polymer-Harz basiert. Dieses Enzym-Polymerharz-Gemisch kann auf Oberflächen mit unterschiedlichen physikalischen oder chemischen Eigenschaften aufgebracht werden. Als Modellenzym wurde die robuste, Co-Faktor unabhängige, monomere Thermomyces lanuginosus Lipase (TLL) genutzt. Die Immobilisierung mittels wasserfreiem Einbettungsverfahren konnte erfolgreich mit Aktivitäten von bis zu 250 mU/cm² beschichteter Oberfläche gegenüber p- Nitrophenyl-Palmitat (pNPPalm) nachgewiesen werden. Die Co-Faktor-abhängige und unter nativen Bedingungen als Homotetramer vorliegende Threonin Aldolase aus Ashbya gossypii wurde als zweites Beispielenzym erfolgreich mit dem wasserfreien Einbettungsverfahren immobilisiert. Somit konnte gezeigt werden, dass das neuartige wasserfreie Einbettungsverfahren auf verschiedene Enzyme mit unterschiedlicher Komplexität anwendbar ist.
Der dritte Ansatzpunkt ist die Entwicklung eines quantitativen Mikrotiter-Lipase-Nachweissystems. Verschiedene labor- und zeitintensive Verfahren weisen lipolytische Aktivität nach. Um ein schnelles und einfaches Lipase-Nachweissystem zu etablieren, wurde ein turbidimetrisches Lipase-Nachweissystem im Mikroliter-Maßstab, basierend auf einer stabilisierten 1 % (v/v) Tributyrinemulsion entwickelt. Durch die Hydrolyse des Tributyrins kommt es zu einer kontinuierlichen Klärung. Das Auftragen variabler Mengen des Modellenzyms TLL zeigte eine direkte Abhängigkeit zwischen Lipasekonzentration und Abnahme der Extinktion bei 595 nm. Eine eingehende Charakterisierung ergab, dass ein Substratüberschuss bei 1 % (v/v) Tributyrin vorliegt. Somit kann das turbidimetrische Mikrotiter-Lipase-Nachweissystem zur Quantifizierung lipolytischer Proben eingesetzt werden.
Jeder der drei Ansatzpunkte trägt das Potential, robust und einfach, unter kostenminimierten Bedingungen Enzyme herzustellen, sie zu immobilisieren sowie lipolytische Aktivität zu quantifizieren. Daraus ergeben sich Anwendungsmöglichkeiten aber auch interessante wissenschaftliche Perspektiven.
We formulate a generalization of the time-dependent Gutzwiller theory for the application to multi-band Hubbard models. Our approach allows for the computation of general momentum- and frequency-dependent two-particle response functions. The in-depth knowledge of them is crucial for the understanding and interpretation of experiments in solid-state physics. In the calculation of ground-state properties of Hubbard models, the Gutzwiller approach is known to overcome the main shortcomings of the Hartree–Fock approximation, whose time-dependent generalization is the standard text-book method for the calculation of response functions. We therefore expect that the time-dependent Gutzwiller theory, that has been formulated only for the single-band Hubbard model so far, will offer a technique yielding new insight into the dynamics of strongly-correlated multi-orbital systems. In this thesis, we motivate the employment of multi-orbital Hubbard models and give an introduction to multi-band Hubbard models in Chapters 1 and 2. Their treatment within the Gutzwiller variational approach is subject of Chapter 3, where it is supplemented by investigations that connect our new approach to previous results. We derive the random-phase approximation as the time-dependent Hartree–Fock theory in Chapter 4, followed by the derivation of the corresponding time-dependent Gutzwiller theory in Chapter 5. We demonstrate the applicability of our new approach in Chapter 6, where we calculate the transversal spin susceptibility of a Hubbard model with two degenerate bands and present numerical results for systems in infinite and three spatial dimensions. A summary and conclusion is given in the final Chapter. Mathematical details of our derivations are presented in several appendices.
The present research aims to analyze the possibilities of introducing the living “Intangible Cultural Heritage” as Supplement of Knowledge into the formal educational system particularly the Early Childhood Education in the Far North Region of Cameroon - irrespective of the 2003 Convention for the Safeguarding of the Intangible Cultural Heritage and the 2005 Convention on the Protection and Promotion of the Diversity of Cultural Expressions. This Region is purposively selected for its stronghold of multifarious and diverse ethno-cultural (id)entities and citadel of the country’s enshrined traditions. The rural area of Kolara is conveniently chosen to explore how to blend the receding ethno-cultural heritage with the formal education system in accordance with the aim of education in Cameroon and therefore could be an example of how to train citizens firmly rooted in their cultures but also opened to the world. It presupposes that the current formal primary educational system is not constructive for primary school starters. On the basis of a combination of participatory research and systematic data collection methods, three educational heritages could be outlined: the ethno-cultural traditional educations specific to the two major ethno-cultures Tupuri and Fulbé and the Islamic Arabic educational heritage peculiar to Muslims, predominantly Fulbé. In this context, it could be determined to what extend the formal education is ethno-cultural specific, environment related and learner centered.
Im Rahmen des Forschungsprojektes werden Fragestellungen des Stahlleichtbaus bezüglich des Einsatzes von strukturierten Blechen hinterfragt, untersucht und Lösungen vorgestellt.
Als Anwendungsbeispiel werden in dieser Arbeit geschweißte I-Träger mit schlanken, strukturierten Stegen untersucht. Eine Serie von Blechträgern mit verschiedenen Stegausführungen - eben, profiliert und strukturiert - wird modelliert und auf ihre Schubtragfähigkeit untersucht.
Die vorliegende Arbeit beschreibt erste Untersuchungen zu strukturierten Blechen mit aktuellen numerischen Analysen und praktischen Versuchen zum globalen und lokalen Beulen.
In Versuchen und numerischen Simulationen werden verschiedenste geschweißte Stahlleichtbauträger untersucht. Es wird erkundet, inwiefern sich das Beulverhalten von Trägern mit strukturierten Stegen gegenüber ebenen oder profilierten Stegen verändert. Außerdem wird definiert, welche Strukturen sich am besten für den Einsatz in Stahlleichtbauträgern eignen.
Schließlich wird ein Vergleich von numerischen und analytischen Versuchsergebnissen aufgezeigt und ein Berechnungsvorschlag gegeben, welcher dazu dient, Stahlleichtbauträger mit strukturierten Blechen bemessen zu können.
Assessing authenticity in heritage conservation : case study : architectural conservation in Bahrain
(2023)
The thesis complements the authenticity discourse in heritage conservation with the perspective of laypeople and evaluates the pertinent methodology for the application of the normative concept in architectural heritage conservation. Based on the Nara Document on Authenticity, the Operational Guidelines for the Implementation of the World Heritage Convention anchor the concept in the credibility and truthfulness of internal and external factors – referred to as information sources – that communicate a heritage site’s cultural values. Conversely, the author explored the truthfulness of messages conveyed to site users in a qualitative research based on interviews focused on two urban reference sites in Bahrain. These stand for different eras and conservation approaches: the ensemble of colonial-style governmental buildings at Bab al-Bahrain in Manama and the vernacular Siyadi Shops in the market area Suq al-Qaisariya in Muharraq, which were restored in the course of a World Heritage nomination. The interpretive content analysis compares how architects and non-architects, who represent laypeople in architectural conservation, perceived their authenticity and also traces cultural contingencies. The empirical data confirms pronounced differences in the way architects and non-architects perceive authenticity but only a few between representatives of so-called Western and Eastern cultures. Assessed against international heritage conservation standards, the site in Muharraq proved more authentic than the one in Manama. However, the meanings produced in the interaction between the sites and the interviewees proved be of limited truthfulness in both cases. A key finding is hence that a constructivist authenticity concept can serve no normative function when heritage conservation is considered a discipline at the service of historiography. While all potential factors of authenticity as per the Nara Document proved to be relevant, perceived material authenticity was found to be an outstanding reason why the site in Muharraq was appreciated more. Its rehabilitation was found to successfully reconcile essentialist and constructivist authenticity understandings by paying tribute both to the documentary value of the historic site and to the experiential needs of its users. The findings support the ICOMOS Venice Charter’s material-focused approach while confirming the relevance of a broadened authenticity understanding and highlighting the importance of integrated, participatory approaches to heritage conservation. By illustrating the importance of expertise when assessing the authenticity of architectural heritage, the findings at the same time flag limits to democratizing architectural conservation practice. The author recommends developing practice-oriented guidance for the assessment of authenticity of heritage sites based on further research and to add interpretation facilities to the list of factors of authenticity.
Die Arbeit dokumentiert die Entwicklung von Algorithmen, mit denen auf mesoskaliger Ebene die Auswirkungen des Wassermanagements in grundwasserregulierten Niederungen auf deren Wasserrückhalt abgeschätzt werden können, ebenso wie damit verbundene Änderungen der Nährstoffeinträge in Fließgewässer. Dies geschieht auf der Grundlage breitenverfügbarer Gebietsinformationen, die in dem Geographischen Informationssystem ARC/INFO verarbeitet werden. Den zeitlichen Bezug bilden langjährige Monatsmittel. Die Algorithmen wurden auf das ca. 1900 km² große Einzugsgebiet des Rhin im Nordwesten des Landes Brandenburg angewendet. Dazu wurde eine Grundvariante entwickelt, für die sich die Grundwasserhaltung aus der Landnutzungsverteilung der 1990er Jahre ableitet. Weitere fünf Szenarien folgen möglichen zukünftigen Zielstellungen der Land- und der Wasserwirtschaft. Der auch auf andere Gebiete des nordostdeutschen Tieflands übertragbare Modellansatz reagierte auf sämtliche Eingabeparameter plausibel. Ein Szenarienvergleich ergab eine Minderung des Gebietsabflusses um 45% zur Grundvariante, was einer Minderung von Stoffeinträgen in die Gewässer von bis zu 177 t N/a und 11 t P/a entspricht.
Einkaufen im Internet ist selbstverständlich geworden: Bücher, Kleidung, Medikamente oder Lebensmittel lassen sich leicht online bestellen. Für Handwerksleistungen gilt das nicht. Viele Handwerksbetriebe haben rückständige Internetpräsenzen und sind nicht digital mit ihren Kunden vernetzt. Allerdings geraten Handwerksbetriebe unter Zugzwang, ihr Angebot im Rahmen von E-Commerce online zugänglich zu machen. Verantwortlich dafür sind das Erwachsenwerden der 'Digital Natives' sowie das Auftauchen neuer, digitaler Konkurrenten.
Die Arbeit untersucht, wie Handwerksbetriebe E-Commerce gemeinsam im Rahmen einer horizontalen Kooperation anbieten könnten. Für die Anbahnung einer solchen Kooperation werden die Relevanz von Gelegenheiten sowie die Einflussfaktoren auf die Akzeptanz solcher Gelegenheiten herausgearbeitet. Gefunden wird, dass die Akzeptanz einer vorgeschlagenen Kooperationsgelegenheit viermal höher ist als die unbedingte Bereitschaft zur Kooperation. Die Akzeptanz einer E Commerce-Kooperationsgelegenheit ohne Eigenkapitaleinlage, mit Konkurrenten als Partner sowie im engen Kooperationsumfang ist außerdem höher als bei anders ausgestalteten Gelegenheiten. Umfang und Konkurrenz der Partner können sich dabei unter bestimmten Bedingungen gegenseitig absichern. Auch die Passung zum Adressaten der Kooperationsgelegenheit ist relevant, vor allem die Komplementarität der Ressourcen.
Ist die horizontale Kooperation angebahnt, kann sie der Überwindung zweier zentraler Hemmnisse des E-Commerce dienen. Dies ist zum einen die geringe E-Commerce-Tauglichkeit handwerklicher Leistungen. Die Arbeit zeigt, dass die E-Commerce-Tauglichkeit einer Leistung immer dann gering ist, wenn sie schwierig zu spezifizieren ist und eine hohe Kontaktintensität bei der Übergabe des externen Faktors erfordert. Solche Dienstleistungen weisen einen geringeren Entwicklungsstand des E-Commerce auf als andere. Ein anderes Hemmnis ist die zunehmend digitaler werdende Mundpropaganda. Hier wird gezeigt, dass Handwerksbetriebe mit kleinem Einzugsgebiet immer dann eine schlechtere Wirksamkeit ihrer Mundpropaganda hinnehmen müssen, wenn diese digital vor allem an nicht-lokale Kontakte weitergegeben wird.
Diese theoretischen Erkenntnisse wurden mit Hilfe einer Befragung von ca. 300 Handwerksbetrieben sowie einer agentenbasierten Simulation gewonnen. Aus den Erkenntnissen werden auch praktische Hinweise abgeleitet.
Das Düsenstrahlverfahren wird vielfältig im Spezialtiefbau zur Baugrundverbesserung, als Verbau- und Gründungselemente sowie zur Abdichtung gegen Grundwasser eingesetzt. Das Düsenstrahlverfahren hat wegen seiner universellen Einsetzbarkeit in den letzten Jahren stark an Bedeutung gewonnen. Wesentliches Ziel bei der Weiterentwicklung des Verfahrens ist die Vergrößerung der Durchmesser Der Düsenstrahlelemente. Eine Möglichkeit ist dabei die Zugabe von Druckluft als so genannte Luftummantelung des Düsenstrahls. Die verfahrenstechnischen Parameter basieren in aktuellen Anwendungen meist auf Erfahrungswerten. Die Luftummantelung wird daher häufig nicht im optimalen Betriebspunkt eingesetzt. Weiterhin sind bisher nur Dreikolbenpumpen in der Lage, die Anforderungen an einen stetigen Massenstrom zu erfüllen. Diese Arbeit stellt ein mathematisches Modell der Luftummantelung vor, mit dem der optimalen Betriebspunkt bestimmt werden kann. Neue Erkenntnisse über die Wirkungsweise der Luftummantelung auf den Düsenstrahl werden durch Staudruckmessungen und Messungen der Schneidkraft gewonnen. Ein weiterer Beitrag zur flexiblen Einsetzbarkeit des Düsenstrahlverfahrens wird durch Verstetigung des Massenstroms einer Zweikolbenpumpe mit Hilfe eines Windkessels erreicht. Dies erlaubt kleinere und kostengünstigere Baustelleneinrichtungen. Sowohl die Wirkung der Luftummantelung als auch die Optimierung der Zweikolbenpumpen werden durch Messungen auf einem speziell konzipierten Prüfstand nachgewiesen.
Baukultur in ländlichen Räumen ist Alltagsbaukultur, die von vielen Akteuren mitgeprägt wird. Ein großer Teil der Verantwortung für das baukulturelle Erscheinungsbild liegt auf kommunaler und regionaler Ebene. Baukultur in ländlichen Räumen kann nicht allein auf das Thema regionstypisches und historisches Bauen reduziert werden und bezieht sich nicht nur auf die Architektur des Gebäudes. Das baukulturelle Leitbild ist weiter gefasst und bezieht die Infrastruktur, die öffentlichen Räume sowie die Kulturlandschaft mit ein. Baukultur im ländlichen Raum ist ein Gemeinschaftswerk Vieler.
Um das landesweite Spektrum widerzuspiegeln, wurden Praxisbeispiele aus Kleinstädten (max. 10.000 Einwohner) und Dörfern aus unterschiedlichen Regionen Brandenburgs untersucht. Im Fokus der Betrachtung steht vor allem die Alltagsbaukultur. Von Interesse sind alle strategischen, planerischen und prozessuale Ansätze, die sich ums Planen und Bauen in ländlichen Räumen drehen und für die zukünftige Entwicklung von Leitbildern, Methoden und Verfahren von Bedeutung sein könnten.
Zielsetzung der Untersuchung ist die Erarbeitung eines Leitfadens für die Stärkung der Baukultur im ländlichen Raum. Die Zielgruppe des Leitfadens sind die Akteure der Baukultur in kleineren Städten und Kommunen der ländlichen Regionen Brandenburgs. Der Leitfaden soll jedoch nicht nur als Dokumentation der Ergebnisse dienen. Der Schwerpunkt wird darin liegen, den Prozess aufzuzeigen, der zu einer gelungenen Baukultur geführt hat. Welche Akteurs- und Trägerkonstellationen, welche Instrumente, rechtliche Grundlagen, Beteiligungsverfahren oder Finanzierung sind bei der Umsetzung zur Anwendung gekommen und können anderen Kommunen als Vorbild dienen?
Biofilme sind Zusammenschlüsse von Mikroorganismen, die eingebettet in einer selbstproduzierten Matrix vor äußeren Umwelteinflüssen geschützt sind und eine erhöhte Toleranz gegenüber Antiinfektiva aufweisen. Im Bereich der Humanmedizin werden 65-80 % aller bakteriellen Infektionen mit Biofilmen assoziiert. Problematisch ist die fehlende Biofilmanalytik in der Routinediagnostik, die auch von der Europäischen Gesellschaft für klinische Mikrobiologie und Infektionskrankheiten gefordert wird. So fehlen standardisierte Methoden für den mikroskopischen Nachweis einer Biofilm-assoziierten Infektion, die in situ Quantifizierung von Bakterien auf Implantaten und die Prüfung der Antibiotikaempfindlichkeit von Bakterien in Biofilmen. Mit den in dieser Arbeit etablierten Methoden wurden diese verschiedenen Schwerpunkte im Bereich der bakteriellen Biofilmanalytik beleuchtet. Basierend auf der an der Hochschule Lausitz entwickelten VideoScan-Technologie wurden fluoreszenzmikroskopische Methoden für die Untersuchung von Biofilmen entwickelt. Es wurde ein Modul geschaffen, welches qualitative und quantitative Aussagen über die allgemeine Fähigkeit von Bakterien zur Biofilmbildung treffen kann. Mit Anwendung dieser Methode konnte der Zusammenhang zwischen den genotypischen und phänotypischen Merkmalen von 187 klinischen E. coli-Isolaten und deren Biofilmbildung untersucht werden. Ein weiteres Modul erlaubte die Untersuchung der mit E. coli besiedelten Materialien Glas, Stahl und Titan. Insgesamt 44 Materialstücke (Coupons) wurden auf die Anzahl adhärenter Bakterien, die besiedelte Fläche und die maximal gebildete Biofilmdicke untersucht. Das dritte und letzte Modul fand Anwendung in der Untersuchung der Antibiotikaempfindlichkeit von S. aureus während der Biofilmbildung und unterschiedlich reifer S. aureus-Biofilme. Innerhalb dieser Arbeit konnte gezeigt werden, dass die etablierte Methode eine umfangreiche Analyse von Biofilmen für verschiedene Fragestellungen ermöglicht.
The integration of germanium (Ge) on silicon (Si) for microelectronics applications requires strain-relaxed SiGe buffer layers (SRB) as virtual substrates. However, the presence of threading dislocations in these layers remains a challenge, as they can affect device performance. Existing methods achieve threading dislocation densities (TDD) around 1 x 10⁵ cm⁻², but a further reduction is desired for industrial applications. A SiGe backside deposition technique originally intended to compensate for wafer bowing surprisingly improves the TDD. The underlying physics remained poorly understood until now. In this work it is shown, that the SiGe backside deposition leads to a parasitic SiGe layer at the edge of the wafer. Partial relaxation of this layer generates dislocations, which fundamentally change the relaxation mechanism of subsequently deposited SiGe layers on the front side. These preexisting dislocations glide from the edge to the center of the wafer, preventing the formation of dislocation bundles and pile-ups. As a result, the TDD decreases significantly for layers with low Ge content. Adjusting the growth conditions and dislocation glide kinetics optimizes early relaxation, achieving a TDD reduction to 4x10⁴ cm⁻² for 25% Ge buffer layers. Additionally, a novel ring deposition technique provides controlled preexisting dislocations at the wafer’s edge, offering better control over the dislocation reservoir than uncontrolled parasitic deposition. Although initial results show promising results, further optimization is needed due to localized mechanical damage during processing. In summary, this research provides insights into strained SiGe layer relaxation, dislocation physics, and their impact on the TDD. By understanding these mechanisms, an enhancement of established buffer approach can be achieved and novel strategies for further TDD reduction can be developed.
We study convexities designed to characterise some of the most fundamental classes of graphs. To this end, we present some known results on this topic in a slightly different form, so as to give a homogeneous representation of a very disparate field. Furthermore, we present some new results on the Caratheodory number of interval graphs and also give a more or less exhaustive account of everything that is known in this context on AT-free graphs, including new results on characterising linear vertex orders and the structure of the intervals of this class.
We introduce the new class of bilateral AT-free graphs which is motivated by the linear order characterisation and the convexity used to describe AT-free graphs. We discuss their relation to other known classes and consider the complexity of recognition. Furthermore, as a consequence of notions from abstract convexity we present algorithmic results with regards to some natural subclasses of these.
As an application of notion of an extreme vertex of a convex geometry, we discuss structural aspects of avoidable vertices in graphs, which form a generalisation of simplicial vertices. This includes a characterisation of avoidable vertices as simplicial vertices in some minimal triangulation of the graph and a new proof of the existence result. Furthermore, we discuss the algorithmic issues regarding the problem of efficient computation of avoidable vertices in a given graph. This is complemented by an algorithmic application of the concept of avoidable vertices to the maximum weight clique problem, by identifying a rather general class of graphs in which every avoidable vertex is bisimplicial. This leads to a polynomial-time algorithm for the maximum weight clique problem in this class of graphs. Implications of this approach for digraphs are also discussed. All of these results lead to a conjecture concerning the generalisation of avoidable vertices to avoidable paths and we prove this conjecture for paths of length less or equal to two.
Finally, we analyse the properties of many different and widely used forms of graph search. Here, we discuss the problem of recognising whether a given vertex can be the last vertex visited by some fixed graph search. Moreover, we present some new aspects of the problem of deciding whether a given spanning tree of a graph is a graph search tree of a particular type of search. We generalise the concept of such trees to many well-known searches and give a broad analysis of the computational complexity of this problem. Both of these discussions are motivated by the use of graph searches in the context of computing properties of convexity.
Since the beginning of its development in the 1950s, mixed integer programming (MIP) has been used for a variety of practical application problems, such as sequence optimization. Exact solution techniques for MIPs, most prominently branch-and-cut techniques, have the advantage (compared to heuristics such as genetic algorithms) that they can generate solutions with optimality certificates. The novel process of additive manufacturing opens up a further perspective for their use. With the two common techniques, Wire Arc Additive Manufacturing (WAAM) and Laser Powder Bed Fusion (LPBD), the sequence in which a given component geometry must be manufactured can be planned. In particular, the heat transfer within the component must be taken into account here, since excessive temperature gradients can lead to internal stresses and warpage after cooling. In order to integrate the temperature, heat transfer models (heat conduction, heat radiation) are integrated into a sequencing model. This leads to the problem class of MIPDECO: MIPs with partial differential equations (PDEs) as further constraints. We present these model approaches for both manufacturing techniques and carry out test calculations for sample geometries in order to demonstrate the feasibility of the approach.
Ecological research on acidic lakes has historically focused on soft-waters, whereas biota in natural and man-made acidic hard-water lakes remains poorly studied. My thesis deals with the effects of multiple abiotic stressors on species and genetic biodiversity of littoral Cladocera in two types of acidic waters in Germany: hard-water mining and soft-water bog lakes. I found that these two types of acidic lakes supported highly distinct cladoceran communities, both with respect to their species diversity and composition, what led to the rejection of my null hypothesis that pH was the only abiotic factor, determining species diversity patterns. Further analyses revealed that, apart from pH, TDS-related parameters and trophy significantly affected species composition of littoral Cladocera in the studied lakes. Particularly the role of TDS and its constituents for colonization of acidic lakes was virtually neglected by previous studies, based on soft-water lakes’ data sets. My study on the genetic diversity of a generalist cladoceran Chydorus sphaericus provided evidence for genetic erosion, i.e. negative effects of abiotic stress in the acidic hard-water mining lakes, but not in the acidic soft-water bog lakes. I conclude that the observed genetic erosion in acidic mining lakes may have negative long-term consequences for population persistence even in broadly tolerant species. In general, biodiversity at both species and genetic levels was much more impaired in the acidic hard-water mining lakes, compared to the naturally acidic soft-water bog lakes. This was possibly due to both ecological (higher abiotic stress) and evolutionary (insufficient time for long-term adaptations to evolve) mechanisms. My results suggest that colonization of acidic hard- and soft-water lakes in each case should require specific physiological adaptations at both species and population levels. The practical relevance of my studies is that they provide the scientific basis for monitoring of acidic hard-water mining lakes based on littoral Cladocera. Especially genetic diversity proved a valuable indicator of water quality in acidic mining lakes, as it provided unique information on population-level responses, being complementary to species diversity assessment. Overall, my results demonstrate that inclusion of acidic hard-water lakes into the research framework as well as comparisons among communities in chemically diverse acidic lakes can result in important new insights, concerning the community organization and adaptations in acidic environments.
Groundwater samples were collected from 63 community wells and boreholes within south-western part of Ashanti Region of Ghana to examine their hydrogeochemical characteristics and elemental features to better understand the sources and mobilization processes responsible for arsenic (As) enrichment as well as the suitability of the groundwater for domestic and agricultural purposes. In addition, gold mine tailings dams were also investigated to ascertain the potential source of As and other trace metals (Fe, Cu, Mn, and Zn) contamination and their dissolution into the adjoining environmental media. Further, two point-of-use As removal technologies were evaluated for their effectiveness and appropriateness. A transparent small volume flow-through cell coupled with a calibrated hand held YSI® Multi-Parameter Water Quality Meter (Model YSI 6 l0-DM/600XL) was used simultaneously to measure indicator field parameters. Anions and cations were determined simultaneously in groundwater samples using Metrohm 761 Compact IC and Dionex 4500i IC system, respectively. Total As and trace metals analysis of the groundwater samples and gold mine tailings were performed on electrothermal and flame atomic absorption spectrometry. As speciation were performed using disposable cartridges. Spatial distribution maps were produced for hydrogen ion concentration (pH), total dissolved solids (TDS), total hardness (TH), electrical conductivity (EC), sodium adsorption ratio (SAR), residual sodium carbonate (RSC) and percentage sodium (% Na) using the geographic information system (GIS). Results for the analysis of groundwater samples from 63 boreholes and wells (depth 1.5-100 m) within the study area demonstrate that the groundwater composition varies from Ca–Mg–HCO3 to Na–K–HCO3 and anoxic in nature. As concentrations ranged from <0.1-72 µg/L and <0.1-83 µg/L during the dry and the wet seasons, respectively. High As concentrations were generally present in the shallow to medium depth (20-70 m) of the aquifer along with high Fe ranging from <0.01-12.3 mg/L and <0.01-16.3 mg/L during the dry and the wet seasons, respectively and relatively low Mn (1.8-498.0 µg/L during the dry season and 2.3-583.8 µg/L during the wet season). The data demonstrated that 59 % of the groundwater samples contained no detectable level of As, 17 and 22 % of the samples gave results with levels of As above the World Health Organization (WHO) guideline value for drinking water standard of 10.0 µg/L, while 24 and 19 % of the samples showed results below the WHO drinking water guideline value during the dry and the wet seasons, respectively. Dissolved inorganic As species predominate with arsenite (As-III) as the main form. It appears that high As concentrations in the study area result from the contribution of different mechanisms which can be grouped into two namely aquifers under oxidizing conditions (aided by sulphide alteration) and aquifers under reducing conditions resulting from the reduction dissolution of arseniferous iron oxyhydroxide that exist as a dispersed phase on the sedimentary grains of the aquifer. In addition, water residence time and different water use practices also influence As concentrations in the groundwater. The results of the gold mine tailings dam revealed elemental concentrations ranging up to 1752 mg/kg As, 75.16 wt.% Fe, 1848.12 mg/kg Mn, 92.17 mg/kg Cu and 177.56 mg/kg Zn. Sulphate was the dominant anion throughout the leachate, reaching a maximum dissolved concentration of 58.43 mg/L. The As concentration levels of the mine tailings were very much higher than the Netherlands soil protection guideline value of 55 mg/kg. A higher amount of the total As content in the mine tailings registered leaching levels in a range of 0.04–0.56 %. It was observed from the study that the groundwater was predominantly soft in nature and its pH in desirable range which is within safe limits for domestic use during the dry season while 82.8 % of the analyzed groundwater samples registered a non-desirable pH range (acidic) during the wet season. The results for the spatial distribution of pH, TDS, TH, EC, SAR, % Na and RSC of the groundwater samples analyzed generally appear to be within safe limits. The two point-of-use As removal technologies evaluated shown that the Three-earthen pot system is the most effective and appropriate technology. Moving forward, it is my anticipation that the findings of this study will serve as a master piece to advice policy makers, well and borehole owners about the dangers or potential risks associated with As and other trace metals in drinking water supplies sourced from groundwater and how these can be managed. In addition, this research has identified high-risk As-contaminated areas, potential health issues, methodology for assessing As in groundwater, and a broad outline of two point-of-use As treatment options which can target risk populations to protect public health and help shape the national, regional, municipal and districts water monitoring policies.
Das deutsche Energieversorgungssystem soll bis zum Jahr 2050 umfassend transformiert werden. Auch wenn es auf dem Pfad zur vollständigen Dekarbonisierung der Energieversorgung noch eine Vielzahl technischer Herausforderungen gibt, ist davon auszugehen, dass an der politischen Ambition einer treibhausgasneutralen Energieversorgung bis spätestens zum Jahr 2045 festgehalten wird. Klimaschutz ist jedoch nur eine Dimension im Spannungsfeld Energiewende. Es gilt, Ökologie, Wirtschaftlichkeit, technische Realisierbarkeit und Versorgungssicherheit sowie gesellschaftliche Aspekte in Einklang zu bringen. Das Ziel dieser Arbeit ist es, einen wissenschaftlichen Beitrag zur Untersuchung eines durch erneuerbare Energieanlagen dominierten Energieversorgungssystems im Jahr 2050 zu leisten. Die Einspeisung elektrischer Energie aus Wind- und Photovoltaikanlagen unterliegt jedoch hohen Fluktuationen. Aus diesem Grund sind im zukünftigen Energieversorgungssystem hohe temporäre Energieüberschüsse und -defizite zu erwarten.
Eine mögliche Lösung könnte hierfür die Sektorenkopplung darstellen. Die vollständige Kopplung dieser Sektoren würde es ermöglichen, hohe Energieüberschüsse sinnvoll zu verwenden oder auftretende Energiedefizite auszugleichen. Bedingt durch die fluktuierende EE-Einspeisung sind die Potenziale zur Nutzung von überschüssiger elektrischer Energie in anderen Energie- und Wirtschaftssektoren im Zeitverlauf jedoch nicht konstant. Aus diesem Grund erscheint es sinnvoll, die Diskussion über Sektorenkopplungspotenziale auf zeitlich und räumlich aufgelöste Untersuchungen zu stützen. Ohne die Prognose und Modellierung von zeitlich und räumlich hoch aufgelösten Einspeise- und Lastzeitreihen ist es nicht möglich, zielführende Aussagen über Sektorenkopplungspotenziale und eine bedarfsgerechte Energiebereitstellung im zukünftigen Energieversorgungssystem zu treffen.
Zur Quantifizierung und Prognose zukünftiger Sektorenkopplungspotenziale wurde im Rahmen dieser Dissertation ein vielseitig einsetzbares Energiemodell entwickelt und detailliert vorgestellt. Hierbei handelt es sich um eine modular aufgebaute, Microsoft Excel-basierte Lösung in Verbindung mit Visual Basic for Applications. So ist es möglich, das Modell auf jedem modernen Windowssystem ohne weitere Software zu verwenden. Das Energiemodell wurde anschließend auf eine geeignete Modellregion für das Jahr 2050 angewendet. Im Energiemodell werden elektrische Erzeugungs- und Lastzeitreihen in stündlicher Auflösung für bis zu 200 Modellknoten (räumliche Auflösung) ermittelt, miteinander verrechnet und auf mehreren Modellebenen aggregiert. Am Beispiel der gewählten Modellregion konnten so die Sektorenkopplungspotenziale im Rahmen einer Sensitivitätsanalyse umfangreich diskutiert werden. Damit war es möglich, die Forschungsfragen dieser Dissertation detailliert zu beantworten.
Unternehmen der Umformtechnik sehen sich vermehrt steigenden Anforderungen bei schwankenden Einflussfaktoren ausgesetzt. Für eine wirtschaftliche Fertigung sind Pressen erforderlich, die sich den steigenden Anforderungen und schwankenden Einflussfaktoren anpassen und mit möglichst hoher Produktivität, Qualität und Wirtschaftlichkeit eine breite Produktpalette fertigen können.
Unter diesen Voraussetzungen bietet sich der Einsatz von kraftgebundenen Servospindelpressen an. Diese ermöglichen frei programmierbare Stößelbewegungsprofile und stellen die Nennkraft über den gesamten Stößelhub zur Verfügung. Allerdings erfüllen die bekannten Servospindelpressen die Forderung nach wandlungsfähigen Pressen, welche an unterschiedliche Anforderungen angepasst werden, besonders die Änderung der Abfolge von Teilprozessen und der Austausch von Maschinenkomponenten, nur sehr eingeschränkt. Aus diesem Grund wird ein neuartiges wandelbares Pressensystem entwickelt. Dieses soll dem Anwender weitreichende Vorteile bringen: Die Nennkraft des Pressensystems wird auf mehrere, in Durchlaufrichtung der Teile frei positionierbare und miteinander koppelbare Pressenmodule mit eigenen Pressenantrieben und -stößeln aufgeteilt. Durch Servospindelantriebe werden prozessangepasste Stößelbewegungsprofile für einzelne Teilprozesse ermöglicht. Dies erlaubt eine wandelbare Anordnung von Teilprozessen, wodurch die Prozesskette skaliert werden kann. Unterstützt wird die Wandlungsfähigkeit des Pressensystems, indem es durch den Anwender erweitert werden kann und sich weitere Prozesse wie Schweißen, Löten oder Kleben integrieren lassen.
Ziel der Arbeit ist die Entwicklung des beschriebenen wandlungsfähigen Pressensystems mit Servospindelantrieb für die Komplettbearbeitung von kleinen Bauteilen. Grundlage bildet die Untersuchung des Standes der Pressentechnik und der Methoden der Produktentwicklung. Der Entwicklungsprozess wird in die Phasen Anforderungsfindung, Konzeptfindung und Entwurfsfindung gegliedert. Zur Überprüfung wird aus dem Entwurf ein Prototyp ausgearbeitet. Im Anschluss werden Maßnahmen zur Produktstrukturierung durchgeführt, aus denen die Weiterentwicklung des Entwurfes zu einer Typengruppe und einem Baukastensystem resultiert. Zum Abschluss wird das Pressensystem bewertet, sein Einsatzspektrum beschrieben und das Pressensystem innerhalb bestehender Pressen eingeordnet.
In der europäischen Baukultur stehen Schlösser, Burgen und Country Houses für politische und soziale Macht. Die Gestaltung sowie Funktion dieser Bauten und deren Umgestaltung lassen Schlüsse über die jeweiligen Bauherren und Architekten zu, so dass spezifische und allgemeine Ansprüche der Gesellschaft für die jeweiligen Zeitschichten verdeutlicht werden. Heute ist das Sichern des Fortbestehens dieser meist denkmalgeschützten Bauten in Zeiten von staatlichen Mittelkürzungen und des Klimawandels schwierig. Für diese Ausgangssituation ist ein autarkes Denkmal, das sein Bestehen aus sich selbst heraus sichert, ohne seiner Substanz zu schaden, der wertvollste Lösungsansatz. Ein solches Beispiel wird in der Dissertation in seiner Gesamtheit analysiert. Anhand der Auswertung verschiedener Quellen wird betrachtet, in welchen Schritten die Eigenständigkeit von Eastnor Castle, Herefordshire, entstand. Die Basis für die Analyse beschreibt der Denkmalwert des Country House, der sich aus einer baugeschichtlichen Untersuchung und architekturhistorischen Einordnung ergibt. Den historischen Wert erhält das von Historic England als Grade I eingestufte Baudenkmal aus den mannigfaltigen Zeugnissen der Familien Cocks, Somers und Somers-Cocks, die diesen Bau über mehrere Jahrhunderte prägen. Darüber hinaus stellt Eastnor Castle ein frühes Werk des Architekten Robert Smirke dar, der im Verlauf seiner Karriere viele architektonisch einflussreiche Bauten entwirft. Ferner besitzt Eastnor Castle einen künstlerischen Wert, da es als kompletter Neubau der Regency Ära durchgängig im Norman Style entworfen und aus Bauten wie Lowther Castle, Cumbria, und Warwick Castle, Warwickshire, entwickelt wird. Ähnliche Country Houses als reine Ausprägung dieser Baustilrichtung existieren nur wenige wie beispielsweise Penrhyn Castle, Gwynedd. Eastnor Castle besitzt ferner Raum- und Mobiliargestaltungen im Norman Style sowie das sehr gut erhaltene Interieur des Gothic Drawing Room, welches A.W.N. Pugin am Ende seiner Architekturkarriere entwirft. Diese Raumgestaltung ist eines seiner am besten erhaltenen Interieurs, das gestalterisch für die internationale Architekturbewegung des Puginism steht. Darüber hinaus besitzt Eastnor Castle eine technikgeschichtliche Bedeutung, da Robert Smirke einerseits neue Baumaterialen wie Eisenträger verwendet und es andererseits in einem neuen Bauablauf errichtet. Außerdem prägen Eastnor Castle und sein Vorgängerbau Castle Ditch die Region der Malvern Hills nachhaltig. In einem zweiten Schritt untersucht die Arbeit die heutige Nutzung des Denkmals und wertet sie aus. Eine wichtige Rolle hierbei spielt das bestehende Funktionsdreieck aus Wohnhaus, Denkmal und Event-Stätte. Das Ausbalancieren dieses Dreiecks hat oberste Priorität und bildet die Grundlage für das autarke Fortbestehen des Denkmals. Einzelne Erkenntnisse dieser Untersuchung können schließlich als Resultate der Arbeit verallgemeinert und übertragen werden.
Um eine höhere Sensitivität für seltene Physikereignisse zu erzielen, wird die Luminosität am LHC in der dritten Upgrade-Phase um den Faktor fünf gesteigert. Die damit verbundene Steigerung der Wechselwirkungsrate bedingt für den CMS-Spurdetektor strahlungshärtere Sensoren. Um das geeignetste Material zu finden, wurde die HPK-Kampagne gestartet. Ziel der Kampagne ist es, die auf dem Markt verfügbaren Siliziumsubstrate und Prozesstechnologien auf ihre Eignung zu überprüfen.
In der vorliegenden Arbeit wurden aus der HPK-Kampagne die sogenannten MPix-Sensoren untersucht. Dafür wurde zunächst eine Probestation in Betrieb genommen und die Steuerungssoftware programmiert. Zusätzlich wurden neuartige Auswertungsmethoden entwickelt und eine Datenbank eingerichtet. Zur Untersuchung der Änderung der Sensoreigenschaften durch Bestrahlung wurden die MPix-Sensoren zunächst vor der Bestrahlung charakterisiert und die Ergebnisse anschließend mit den Ergebnissen nach Bestrahlung verglichen. Der Untersuchungsfokus lag auf dem Einfluss des Sensorsubstrats, der Produktionstechnologie und der Bias-Strukturen und der Strahlenhärte. Durch Bestrahlung degenerierten die Sensortypen unterschiedlich stark. Der Anstieg des Stromes durch Bestrahlung ist kleiner für Sensoren aus Magnetic-Czochralski-Silizium verglichen mit Sensoren aus Float-Zone-Silizium. Für Sensoren aus Float-Zone-Silizium ist der Stromanstieg schwächer für 200 µm dicke Sensoren verglichen mit 320 µm dicken Sensoren. Bias-Strukturen aus Polysilizium und Punch-Through-Struktur werden durch die Bestrahlung geschädigt. Bei Strukturen aus Polysilizium steigt der Widerstand durch Bestrahlung um etwa 50% und bei der Punch-Through-Struktur steigt die Punch-Through-Spannung um den Faktor zwei.
Die Arbeit Raumzeitliche und soziale Entwicklung der Stadt Recife im 20. Jahrhundert. Eine Analyse des Werdens von Raum ist eine empirische Forschung. Die existierenden sozial-räumlichen Verbindungen zwischen Stadtbezirken in Recife werden wissenschaftlich untersucht, weil im persönlichen Erleben der Metropole ich erfahre, dass der Kontaktraum der Stadt, sich anders darstellt als der durch Barrieren physisch gekennzeichnete segregierte Raum es erwarten lässt. Meine Hypothese ist, dass sich Stadtgebiete sozial wie räumlich stark voneinander unterscheiden, jedoch die Interaktionen der Stadtbewohner sich positiv auf die gebaute Stadtstruktur auswirken. Die Forschung orientierte sich bei der Datenerhebung (qualitative Interviews, Stadtspaziergänge, Plananalyse, Gesetzesanalyse, Mental maps, Auswertung statistischer Daten, Sekundärliteratur) an den Aspekten der Raumsoziologie Martina Löws, Spacing und Syntheseleistung. Die Analyse der erhobenen Daten wurde mithilfe der Theorie der Produktion des Raumes von Henri Lefèbvre ausgewertet. In der Arbeit wurde die Stadt Recife in seiner Gesamtheit aufgenommen und in die Analyse des Werdens von Raum überführt. In der sozialen Praxis wurde die durch Bauten geschaffene Segregation akzeptiert, sie nahm diese aber als sozial inexistent wahr. In der räumlichen Konfiguration Recifes trat die Stadt als Mittlerin zwischen dem Staat beziehungsweise dem Weltmarkt und dem Privatem auf und bot das Aktionsfeld, auf dem Konflikte ausgetragen wurden. Bei diesen mal das Eine und mal das Andere überwog. Die Stärke des abstrakten Raumes, der Industrie und des Weltmarktes, gab es in Recife ebenso wie die zahlreichen und akzeptierten Demonstrationen, Kundgebungen und sozialen Veranstaltungen, die für den differenziellen Raum standen. Man akzeptierte zum Beispiel illegales Stromzapfen von einer landesweit agierenden Telefongesellschaft ebenso wie das offensichtliche Stromzapfen von bedürftigen Privatleuten. Die Forschungsarbeit lässt das Postulat zu, dass Recife differenziellen urbanisierten Raum produziert. Dieser differenzielle Raum ist historisch gewachsen und durch die Verfassung Brasiliens auch geschützt. Die Analyse des Werdens von Raum, die über die Integration der Forschungsdaten in die Formanten der lefèbvreschen Theorie der Produktion des Raums realisiert wird, gibt die Möglichkeit Heterogenität und Vielschichtigkeit des Werdens von Raum zu analysieren. Die dialektische Analyse des Werdens von Raum für weitere Stadtgebiete weltweit durchzuführen, um damit eine vergleichende Analyse des Werdens des Raums durchzuführen, ist gegeben.
Within the last decades, the number of social networks is growing fast. The competition of retaining the customers to grow their platform and increase their profitability is rising. That is why companies need to detect possible churners to retain these. The problem of predicting the users’ lifetime, churning users, and the reasons for churning can be tackled by using machine learning.
The goal of this bachelor thesis is to build machine learning models to predict user churn and the user lifetime within the social network Jodel, a location-based anonymous messaging application for Android and iOS.
To get the best possible prediction results, we have started with extensive literature research, whose approaches we have tested and added to a machine learning pipeline to build predictive models. With these models, we have investigated the performance after different observation time windows and have finally compared the strongest models to detect similarities and understand the insights to learn their behaviour.
The results of this thesis are machine learning models for a selected representative set of communities varying in size within the Kingdom of Saudi Arabia and a country model leveraging all data. These models are used for a regression task by predicting the lifetime of a user and a multi-label classification of a user into six different churn classes. Additionally, we have also given models for a binary classification, where the model will predict if the user will churn within a given time or not. These models have shown general strong predictive power, which is shrinking when limiting the observation time window. Especially the binary classification yielded high accuracy of over 99%.
The best models have been used for predicting user churn within other communities to detect communities with possible similar behaviour. These similarities then have been determined by features’ importance, where the most important features have got fed back into empirics. This has shown statistically significant differences between user groups with a different active time but as of today no clear trends were visible that had led us to define the communities’ behaviours.
Since the competition of social networks is still growing, the retaining of users will stay a core marketing strategy, which will need to be tackled by machine learning and artificial intelligence. The created models could be useful for predicting churning users within the platform Jodel to detect these customers that will churn within a given time.
Researches did not focus much on anonymous and location-based messaging. That is why the results of this thesis on the anonymous messaging application Jodel opens a variety of possible tasks for the future in this context.
Untersuchung von aktuellen Trends und Herausforderungen im Supply Chain Management in Deutschland
(2023)
Diese Studie untersucht die aktuellen Trends und Herausforderungen im Supply Chain Management (SCM) in Deutschland anhand von 16 Interviews, die von November 2022 bis Januar 2023 durchgeführt wurden. Die Studie deckt sechs Themenbereiche ab: aktuelle Ereignisse, Veränderungen im SCM, Nachhaltigkeit, Software, neue Technologien und Sichtbarkeit. Die am häufigsten genannten Herausforderungen waren Ressourcenverfügbarkeit, lange Durchlaufzeiten, Fachkräftemangel und preisbedingte Probleme. Die Experten wurden zu aktuellen Ereignissen wie Schwankungen der Rohstoffpreise, Chinas Null-Covid-Strategie und logistischen Engpässen befragt. Die Studie zeigt, dass die Lieferketten komplexer geworden und gewachsen sind und sich die Qualität der Vernetzung verbessert hat. Nachhaltigkeit wird immer wichtiger, und Zertifizierungen können deren Bedeutung belegen. Die Anpassungsfähigkeit von ERP-Systemen wurde kritisiert, und cloudbasierte Lösungen werden aus Sicherheitsgründen gemieden. Neue Technologien wie AR, VR, IoT, Big Data, KI, Additive Manufacturing und Blockchain haben Anwendungspotenzial im SCM. Experten halten Transparenz für wichtig, aber sie ist noch gering und hat das Potenzial, Risiken zu erkennen. Tracking und Tracing sind intern weit verbreitet, aber international gibt es Probleme. Die Studie liefert Erkenntnisse für Unternehmen, um sich anzupassen und weiterzuentwickeln, damit sie künftige Krisen besser bewältigen können.
Die vorliegende Bachelorarbeit analysiert systematisch die Einflüsse zweier Verstimmungseffekte auf das lineare Schwingungsverhalten von Turbinenlaufstufen am Beispiel zweier FE-Modelle. Zum einen wird der Einfluss der geometrischen Verstimmung anhand der probabilistischen Modellierung der Elastizitätsmodule pro Schaufel analysiert. Zum anderen wird der Einfluss einer linearen Approximation der Kontaktverstimmung analysiert. Dazu wird die modale Dämpfung pro Mode probabilistisch modelliert. Zur probabilistischen Modellierung kommen mehrere ausgewählte Wahrscheinlichkeitsverteilungen zum Einsatz.
Bei der Auswertung der FE-Simulationen wird zwischen geometrischer Verstimmung und gleichbleibender modaler Dämpfung sowie geometrischer Verstimmung und gleichzeitiger Variation der Dämpfung unterschieden. Im ersten Fall ergeben sich bis zu doppelte Amplituden im Vergleich zum unverstimmten Modell. Der Einfluss der zusätzlichen Dämpfungsverstimmung ist in den durchgeführten Simulationen deutlich größer als bei realen Messungen und führt bis zu einer 3,3-fachen maximalen Amplitude. Aufgrund dessen zeigt sich, dass der verwendete Ansatz der linearen Modellierung der Dämpfung nur bedingt anwendbar ist.
Darüber hinaus wird eine Methode zur Ermittlung der äquivalenten linearen Dämpfung anhand transienter Analysen für verstimmte Turbinenlaufstufen numerisch validiert. Die Grundidee ist die Bestimmung der linearen Dämpfung aus dem Verhältnis der Mittelwerte der Amplituden bei einer niedrigen und einer hohen Beschleunigungsrate. Die anhand der Methode bestimmte Dämpfung zeigt eine Abweichung im Bereich von maximal 10% im Vergleich zur tatsächlichen Dämpfung.
Ergänzend findet ein Vergleich der Ergebnisse der Finite Elemente Analyse und eines Reduced Order Codes auf Grundlage der Craig-Bampton Methode statt sowie der Vergleich zwischen zwei Sampling-Methoden, dem Simple Random Sampling und dem Latin Hypercube Sampling.
Die Arbeit trägt dem Sachverhalt Rechnung, dass Unschärfe in der Technologiefrühaufklärung als unvermeidbarer Teil der Realität akzeptiert werden muss, aber dennoch unter diesen Rahmenbedingungen Entscheidungen über die zukünftige technologische Ausrichtung von Unternehmen getroffen werden müssen. Hierzu fehlte bisher eine geeignete methodische Unterstützung und Vorgehensweise innerhalb des Technologiefrühaufklärungsprozesses. Die Arbeit leistet in diesem Zusammenhang einen Beitrag zur maßgeblichen methodischen Verbesserung der Technologiefrühaufklärung.
Das Ergebnis der Arbeit ist ein Prototyp eines wissensbasierten Fuzzy-Systems zur Entscheidungsunterstützung und Verbesserung der Entscheidungsgrundlagen innerhalb des Technologiefrühaufklärungsprozesses durch die Integration und systematische Weiterverarbeitung unscharfer Informationen sowie die Entwicklung systematischer Transformationsvorschriften zur Überwindung der methodischen Fragmentierung innerhalb des Technologiefrühaufklärungsprozesses. Das Anwendungspotential liegt insbesondere in einer realitätsnäheren Abbildung und inhaltserhaltenden Verarbeitung von unscharfem Expertenwissen sowie einem daraus resultierenden differenzierteren Informationsgehalt der Entscheidungsgrundlagen für die Ableitung von Entscheidungen und Strategien zur Sicherung der technologischen Wettbewerbsfähigkeit von Unternehmen.
Abschlusssachbericht zum AG Turbo Verbundforschungsprojekt COOREFLEX-turbo, Teilprojekt 1.3.6
In der industriellen Praxis beginnt die Entwicklung eines neuen Verdichters aufgrund der hohen Systemkomplexität stationärer Gasturbinen typischerweise mit einfachen, eindimensional mittelnden Modellen, mit denen bereits grundsätzliche Festlegungen getroffen werden können, und setzt sich über zweidimensionale Strömungsbetrachtungen fort bis hin zu dreidimensionalen CFD- und FE-Rechnungen.
Dies erfordert den Einsatz unterschiedlicher Experten aus verschiedenen Disziplinen der Aerodynamik, Strukturdynamik und Konstruktion, und ist verbunden mit einem hohen Aufwand an manuellem Datenaustausch zwischen den einzelnen Analyseprogrammen sowie einer Abstimmung zwischen den unterschiedlichen Auslegungszielen. Ziel des Forschungsvorhabens war daher die Automatisierung des multidisziplinären und bislang manuell und sequenziell ausgeführten Entwicklungsprozesses für den Verdichter einer stationären Gasturbine beim Industriepartner Alstom. Im Rahmen des Forschungsvorhabens wurden die bereits in vorangegangenen Forschungsprojekten entwickelten Prozesse für die Auslegung von Flugtriebwerken auf die höhere Stufenanzahl von stationären Gasturbinen angepasst und entsprechend erweitert. Für die multidisziplinäre Optimierung von Verdichterschaufeln wurde zunächst ein geeignetes Geometriemodell definiert, welches aerodynamischen und strukturellen Anforderungen Rechnung trägt. Für die aerodynamische Bewertung der Verdichterschaufeln konnte die Q3D Auswertung um eine 3D-CFD Analyse ergänzt werden. Zur strukturdynamischen Analyse wurde ein Verfahren zur automatisierten Identifikation von Eigenformen entwickelt, um Eigenform-abhängige Bewertungen durchführen zu können. Durch die Implementierung von Datenbanken in der Verbindung mit Antwortflächenverfahren konnten die strukturellen und aerodynamischen Auswertungen in hohem Maße parallelisiert und ein effizienter, generischer multidisziplinärer Optimierungsprozess entworfen werden.
Die Konstruktion eingebetteter Systeme, die starke Realzeit-Anforderungen zu erfüllen haben, wird in den verschiedensten Anwendungsbereichen immer bedeutsamer, z. B. in der Medizin, der Transporttechnik oder der Produktionsautomatisierung. Formale Methoden unterstützen die fehlerarme Entwicklung solcher Systeme, weil sie auf einer präzisen mathematischen Grundlage aufbauen. Der Autor entwickelt einen geeigneten Modellierungsformalismus und effiziente Verifikationsverfahren für den Einsatz einer formalen Methode. Durch die Einführung eines Modulkonzepts wird die Modellierung auch großer Realzeit-Systeme systematisch unterstützt. Für die Verifikation werden effiziente BDD-basierte Algorithmen verwendet, wobei auch das Problem des Findens guter BDD-Variablenordnungen gelöst wird. Es werden sowohl Erreichbarkeitsanalyse als auch Verfeinerungsanalyse unterstützt. Die Praktikabilität der Ansätze zur Modellierung und Verifikation werden in verschiedenen Fallstudien aus den Bereichen der reaktiven Systeme und der Kommunikationsprotokolle demonstriert.
In 2012 a group of researchers proposed a basic research initiative to the German Research Foundation (DFG) as a special priority project (SPP) with the name: Wireless 100 Gbps and beyond. The main goal of this initiative was the investigation of architectures, technologies and methods to go well beyond the state of the art. The target of 100 Gbps was set far away from the (at that time) achievable 1 Gbps such that it was not possible to achieve promising results just by tuning some parameters. We wanted to find breakthrough solutions. When we started the work on the proposal we discussed the challenges to be addressed in order to advancing the wireless communication speed significantly. Having the fundamental Shannon boundary in mind we discussed how to achieve the 100 Gbps speed.
The main focus of the presented research is the development and experimental study of radiation-tolerant clock generation circuits intended for applications in high energy physics (HEP). Clock synthesis and the synchronization of systems on the scale of large experimental detectors is an important aspect of their successful implementation and a necessity for achieving their anticipated performance. Developments in this area to increase radiation tolerance and performance are motivated by emerging requirements for clock generation and distribution.
The thesis reviews the requirements of existing and emerging systems with regards to radiation-tolerant clock generation. To characterize clock generation circuits and adequately assess their conformity with the identified requirements in radiation tests, a number of methods and instrumentation setups are developed and characterized. The presented approaches combine aspects of digital programmable logic, analog circuit design and and digital signal processing concepts.
To address design challenges in deep submicron CMOS nodes, the design of radiation-tolerant all-digital PLL and CDR circuits is explored in this thesis. These circuits promise opportunities to improve the radiation tolerance of clock generators, and hence this thesis devises the design of a radiation-tolerant ADPLL/CDR circuit compatible with requirements of high energy physics (HEP) electronics. Using radiation testing, the sensitivity of the circuits is studied and mitigation strategies for identified limitations are discussed. Three such ADPLL/CDR circuits are developed and tested in the form of macro blocks targeting applications in frontend ASICs for high energy physics. The circuits demonstrate jitter performance, power efficiency and radiation tolerance comparable to or better than currently used conventional PLL circuits.
As a final aspect, the improved testing instrumentation and methodology developed within this thesis is applied to uncover a previously unrecognized radiation sensitivity in a conventional, radiation-hardened clock generator circuit. An integrated planar on-chip inductor is experimentally identified as responsible for this sensitivity. Irradiation tests are performed to study and characterize the nature of this sensitivity. The results suggest that energy deposition, likely within dielectric materials surrounding the inductor wiring, alters the inductor's terminal impedance. This stimulates frequency errors with long recovery times in the oscillator. The manifestation of this effect in HEP radiation environments is studied using proton irradiation, where a mitigation strategy is experimentally validated. A reduction of the impact of this sensitivity is demonstrated. To help conclusively identifying the underlying mechanism responsible for the sensitivity within the inductor itself, further research opportunities are suggested.
Vor dem Hintergrund der aktuellen, durch die SARS-CoV-2-Pandemie bedingten, Schulschließungen informiert diese Sonderauswertung der HBSC-Studie im Auftrag des Ministeriums für Bildung, Jugend und Sport des Landes Brandenburg über Rahmenbedingungen für digital unterstützten Heimunterricht. Es werden Befragungsdaten zur familiären Unterstützung sowie zur Verfügbarkeit von Computern und Heimarbeitsplätzen bei SchülerInnen der Jahrgangsstufen 5, 7 und 9 in Brandenburg präsentiert.
Vorgestellt wird ein Interventionsansatz für Mobbing in der Schule. Er beruht auf der Grundannahme, dass Mobbing an Schulen ein multifaktoriell bedingtes Phänomen mit Determinanten auf individueller, sozialer und kontextueller Ebene ist. Der Interventionsansatz ist durch eine ganzheitliche, kooperative Herangehensweise gekennzeichnet. Er beruht auf Forschungsbefunden zu Lehrerkompetenzen im Umgang mit Mobbing sowie zur Wirksamkeit spezifischer Interventionsstrategien. Wichtige Anregungen lieferten der No Blame Approach sowie weitere Interventionsprogramme und -empfehlungen.
Beschrieben wird ein grundlegendes Vorgehen in fünf Teilschritten, das je nach Art des Mobbingfalls adaptiert werden kann. Variationen betreffen insbesondere das Ausmaß der notwendigen Kooperationen, den Einbezug externer psychosozialer Beratungsangebote sowie das Ausmaß der Konfrontation, mit der den mobbenden Lernenden begegnet wird.
Die neu aufgelegte Handreichung des Instituts für Stadtplanung an der BTU Cottbus - Senftenberg steht den Studierenden als Ratgeber für wissenschaftliches Arbeiten zur Verfügung. Sie beinhaltet formale Anforderungen an schriftliche Studienleistungen wie Hausarbeiten, Bachelor- oder Masterarbeiten, Thesenpapiere, Essays, Exposés, Abstracts oder Lerntagebücher. Verschiedene Zitierstile, direkte und indirekte Zitation etc. werden ausführlich erläutert. Neben dem Zitieren von Rechtsvorschriften, Gerichtsentscheidungen und Internetquellen wird der Umgang mit Abbildungen und Karten detailliert dargestellt.
Der stete Zuwachs des Erzeugungsleistungs- und Energieaufkommens aus erneuerbaren Energien (EE) wirkt sich immer deutlicher auf die elektrischen Energieversorgungsnetze aus. Die Folge: Hohe Leistungsgradienten der Erzeugung und kritische Auslastungsgrade der Übertragungs- und Verteilnetze. Räumlich verteilte Energiespeicher können helfen, die EE besser zu integrieren und resultierende negative Effekte zu egalisieren.
Der durch die Bundesregierung proklamierte Entwicklungsplan der sog. Energiewende fordert eine deutliche Zunahme des Anteils der EE und der Elektromobilität. Diese auch zukünftig gewünschte Entwicklung könnte die gegenwärtig betriebenen Energieversorgungsnetze weiter stärker belasten.
Die vorliegende Arbeit bietet einen möglichen Lösungsbeitrag der Elektrofahrzeuge als Speichertechnologie für die Bewältigung der Herausforderung der netzverträglichen Integration von EE und Elektromobilität. Hierzu wird ein Konzept zur Einbindung mobiler Speicher (Elektrofahrzeuge mit V2G-Fähigkeit) vorgestellt. Dieses Konzept wird in einem Reallabor an der Brandenburgischen Technischen Universität Cottbus-Senftenberg evaluiert. Insbesondere die Informations- und Kommunikationstechnologie zwischen Elektrofahrzeug, Ladesäule und einem Aggregator wird eingehend betrachtet, denn sie bildet einen Grundpfeiler der Nutzbarmachung mobiler Speicher.
Hinsichtlich der eingesetzten prozessualen Intelligenz zur Bewältigung nötiger Verfahren und Methoden werden ein Lademanagementsystem für die Ladesäulen und ein Energiemanagementsystem für den Aggregator eingeführt. Beide lassen die externe Verwaltung der Prozesse durch einen Betreiber zu. Es folgt eine Untersuchung der empirischen Verfügbarkeit der Elektrofahrzeugflotte während eines mehrmonatigen Betrachtungszeitraumes. Die Auswertung und Analyse dieser Verfügbarkeit liefert konkrete Ergebnisse hinsichtlich einer Abschätzung zukünftiger Nutzungspotentiale eines mobilen Speichers. Abschließend werden zu erwartende Auswirkungen der Nutzung der mobilen Speicher auf die kalendarische sowie zyklische Alterung der Traktionsbatterie diskutiert.
In dieser Arbeit wird die Entwicklung einer neuartigen fasergekoppelten Wellenleiterweiche beschrieben, womit erstmals das Anwendungspotential elektrooptisch induzierter Wellenleiter für komplexe faseroptische Anwendungen aufgezeigt wird. Die entwickelte Wellenleiterweiche kann das Licht einer Glasfaser auf zwei Glasfasern sowohl wechselseitig schalten als auch mit steuerbarem Leistungsverhältnis aufteilen. Hierzu wird das Prinzip elektrooptisch induzierter Wellenleiter genutzt. Bei diesem Prinzip entsteht in einer aus elektrooptischem Material bestehenden Schicht durch die lokale Brechzahländerung infolge eines elektrischen Feldes oberhalb einer Elektrode ein reversibler Wellenleiter. In den mittels Halbleitertechnologien gefertigten Wellenleiterstrukturen dient das flüssigkristalline Nematogen 5CB als elektrooptisches Material. Hierbei besitzt dessen paranematische Phase eine hohe Transmission über einen breiten Wellenlängenbereich, einen ausgeprägten elektrooptischen Kerr-Effekt und eine Relaxationszeitkonstante kleiner einer Mikrosekunde. Neben dem Kerr-Effekt treten in paranematischen Flüssigkristallen elektrooptische Effekte höherer Ordnung und ein für die Anwendung kritischer feldinduzierter nematisch-paranematischer Phasenübergang auf. In diesem Zusammenhang wird die Eignung paranematischer Flüssigkristalle hinsichtlich der Verwendung in elektrooptisch induzierten Wellenleitern mittels des im Rahmen dieser Arbeit entwickelten Dünnschichtrefraktometers untersucht.
In dieser Arbeit wird die Entwicklung einer neuartigen fasergekoppelten Wellenleiterweiche beschrieben, womit erstmals das Anwendungspotential elektrooptisch induzierter Wellenleiter für komplexe faseroptische Anwendungen aufgezeigt wird. Die entwickelte Wellenleiterweiche kann das Licht einer Glasfaser auf zwei Glasfasern sowohl wechselseitig schalten als auch mit steuerbarem Leistungsverhältnis aufteilen. Hierzu wird das Prinzip elektrooptisch induzierter Wellenleiter genutzt. Bei diesem Prinzip entsteht in einer aus elektrooptischem Material bestehenden Schicht durch die lokale Brechzahländerung infolge eines elektrischen Feldes oberhalb einer Elektrode ein reversibler Wellenleiter. In den mittels Halbleitertechnologien gefertigten Wellenleiterstrukturen dient das flüssigkristalline Nematogen 5CB als elektrooptisches Material. Hierbei besitzt dessen paranematische Phase eine hohe Transmission über einen breiten Wellenlängenbereich, einen ausgeprägten elektrooptischen Kerr-Effekt und eine Relaxationszeitkonstante kleiner einer Mikrosekunde. Neben dem Kerr-Effekt treten in paranematischen Flüssigkristallen elektrooptische Effekte höherer Ordnung und ein für die Anwendung kritischer feldinduzierter nematisch-paranematischer Phasenübergang auf. In diesem Zusammenhang wird die Eignung paranematischer Flüssigkristalle hinsichtlich der Verwendung in elektrooptisch induzierten Wellenleitern mittels des im Rahmen dieser Arbeit entwickelten Dünnschichtrefraktometers untersucht.
Die Institutionalisierung eines organisationalen Feldes : das Beispiel der Elektrizitätswirtschaft
(2007)
In Übereinstimmung mit dem neoinstitutionalistischen Ansatz können Institutionen als verallgemeinerte Verfahren der Praxis definiert werden, deren Geltung innerhalb sozialer Systeme die größtmögliche nämlich allgemeine Ausdehnung zukommt und die im Zweifel so ausgelegt sind, dass nicht kampf- und kostenlos von ihnen abgewichen werden kann. In diesem Sinne regulieren Institutionen soziales Handeln; sie ermöglichen es jedoch auch erst. In neoinstitutionalistischen Untersuchungen wird folgerichtig auf die Bedeutung von Institutionen verwiesen und auch regelmäßig gezeigt, dass Institutionen entstehen oder entstanden sind. Allerdings geschieht dies in der Regel anhand eines Vergleichs der Situation zum Zeitpunkt A (vor der Institutionalisierung) und zum Zeitpunkt B (nach erfolgter Institutionalisierung). Auf diese Weise können zwar Unterschiede zwischen verschiedenen Zuständen aufgedeckt werden, allerdings mangelt es an Darstellungen, die erklären, wie Institutionen entstanden sind, wie verschiedene Institutionen sich aneinander anlagern oder einander verdrängen, kurz: Welche Prozesse der Entstehung, Veränderung und Auflösung von Institutionen zugrunde liegen. Institutionalisierungsprozesse stellen gleichsam einen bilden Fleck des neoinstitutionalistischen Ansatzes dar. Am Beispiel Elektrizitätswirtschaft werden in dieser Arbeit Institutionalisierungsprozesse untersucht. Besondere Aufmerksamkeit ist dabei auf die Basisinstitutionen der Elektrizitätswirtschaft gerichtet. Mit den Richtlinien für den „Bau großer Elektrizitätswerke“ veröffentlichte Georg Klingenberg (1913 und 1914) am Vorabend des ersten Weltkriegs das grundlegende elektrizitätswirtschaftliche Konzept des 20sten Jahrhunderts, ein Konzept, das im Jahrzehnt nach dem ersten Weltkrieg zum nahezu unangreifbaren Dogma wurde. Dieses Konzept beruhte zum einen auf der Idee der „Großkrafterzeugung“, die eine Stromerzeugung in Großkraftwerken, eine koordinierte Einsatzplanung der Primärenergieträger sowie die Optimierung des Kraftwerkseinsatzes gestaffelt nach Grund-, Mittel- und Spitzenlastkraftwerken vorsah. Zum anderen wurde die Idee der Stromerzeugung in Großkraftwerken ergänzt um die Idee der Übertragung der elektrischen Arbeit über weite Strecken mittels eines Hochspannungsnetzes sowie der angebots- und bedarfsausgleichenden ‚Verbundwirtschaft’. Damit wurde der Grundstein für eine Doktrin der ‚economies of scale’ gelegt, welche die Elektrizitätswirtschaft seither stärker prägen sollte, als alle anderen Wirtschaftsbereiche. Von diesem Befund ausgehend, wird dann aus neoinstitutionalistischer Sicht die Transformation der ostdeutschen Elektrizitätswirtschaft und in einem weiteren Schritt die Liberalisierung der Elektrizitätswirtschaft behandelt
In regionalen Klimamodellen wird die untere Randbedingung durch Bodenmodelle bereitgestellt. Diese beinhalten Modellformulierungen, die eine große Anzahl an Eingabeparametern benötigen. Die exakte Bestimmung dieser Parameter stellt ein Problem dar, da sie für ein großes Gebiet in hoher räumlicher und teilweise zeitlicher Auflösung erfolgen muss. Die unterschiedlichen Bestimmungsmethoden tragen dazu bei, dass für viele Oberflächen- und Bodenparameter nur ein möglicher Wertebereich angegeben werden kann. Die Auswirkungen dieser ungenauen Kenntnis der Parameter auf die Ergebnisse regionaler Klimasimulationen mit dem CLM wurden untersucht. Für den LAI, den Vegetationsbedeckungsgrad, die Wurzeltiefe, die Vegetationsalbedo, den Stomatawiderstand, die Bodenart und die Wärmeleitfähigkeit konnten Veränderungen der Modellergebnisse im Jahresmittel von 2-6 W/m^2 der Energiebilanzgrößen und 0,25 K der 2m-Temperatur nachgewiesen werden. Im Monatsmittel ergeben sich Veränderungen bis 20 W/m^2 für die turbulenten Wärmeflüsse und bis 1,5 K für die 2m-Temperatur. Es konnte gezeigt werden, dass die resultierenden Unsicherheiten in den Modellergebnissen dabei räumlich und zeitlich variieren und stark vom Bodenwassergehalt beeinflusst werden. Die Benutzung zweier neuer Parameterdatensätze führte in den Simulationen zu einer Erwärmung bis 0,5 K im Jahresmittel und konnte damit die gegenüber Beobachtungsdaten vorhandene Temperaturabweichung von 1,5 K des Modells reduzieren.
Eines der am intensivsten untersuchten Probleme aus dem Bereich der Optimierung stellt das sogenannte Traveling Salesman Problem (TSP, in deutsch: Handlungsreisendenproblem) dar. Die Aufgabe hinter dem Handlungsreisendenproblem besteht darin, für eine gegebene Anzahl an Orten eine Route zu entwickeln, sodass die Gesamtlänge der Route minimal ist. Zudem darf kein Ort, bis auf den ersten, mehrmals besucht werden. Ziel der vorliegenden Bachelorarbeit ist es, statistische Untersuchungen bezüglich der Tourlänge des TSP in Abhängig der Anzahl der besuchten Städte vorzunehmen, wobei der Fokus auf einer kleinen Anzahl von Städten liegt. Dazu wurde das Problem einerseits numerisch gelöst und die Verteilung der Lösungen analysiert. Für Teilaspekte wurden analytische Lösungen berechnet.