@phdthesis{An2015, author = {An, Ni}, title = {Statistical analysis of extreme climate events in Brandenburg}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-36117}, school = {BTU Cottbus - Senftenberg}, year = {2015}, abstract = {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.}, subject = {Bias correction; Climate simulation; CLM model evaluation; Climate signal analysis; Bias Korrektur; Klima Simulation; CLM Modell Auswertung; Klima Signal Analyse; Brandenburg; Klima; Modell; Statistische Analyse; Simulation}, language = {en} } @phdthesis{Andolfo2017, author = {Andolfo, Franco}, title = {Energieeffizientes N{\"a}hrstoffsplitting von fl{\"u}ssigen Wirtschaftsd{\"u}ngern mittels Membranfiltration}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-42805}, school = {BTU Cottbus - Senftenberg}, year = {2017}, abstract = {Die definierte Selektivit{\"a}t der Membranfiltration kann dazu genutzt werden, einzelne spezifische G{\"u}lle-Separationsprobleme in {\"u}bergeordneten Aufbereitungsklassen zusammenzufassen. Mit dem Ansatz einer gesteuerten N{\"a}hrstofftrennung bzw. Teilzusammenf{\"u}hrung von modifizierten Str{\"o}men, und der Zuordnung von spezifischen Aufgaben an die Mischprodukte, werden die Nachteile des Ausgangsrohstoffs reduziert und der Wertstoff G{\"u}lle r{\"u}ckstandsfrei nutzbar gemacht. Mit einem Anlagenmodell, bestehend aus einer Hydrotankpresse als Vorfiltration und einer Ultrafiltration als Kernkomponenten, ist es {\"u}ber empirisch ermittelte Betriebsparameter m{\"o}glich, einen energetisch optimierten und kontinuierlichen Produktionsbetrieb durchzuf{\"u}hren. Als Produkte der dezentralen Aufbereitungsanlage werden ein emissionsreduzierender Fl{\"u}ssigd{\"u}nger, eine als Brennstoff und als G{\"a}rsubstrat 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 g{\"u}nstigen Anlagenbetriebspunkten wird das Anlagenverhalten hydraulisch steuerbar. Durch die Zuordnung von Anlagenzust{\"a}nden zu differenziertem Sp{\"u}lverhalten, wird die direkte Einflussnahme der Temperatur auf den Permeat-Flux erkennbar. Der Einsatz eines Tauchk{\"u}hlers, mit voreingestellten Grenztemperaturen, stabilisiert signifikant das Anlagenverhalten im Vergleich zu konventionellen Anlagenkonfigurationen. Die Anwendung einer Hydropresse gestattet h{\"o}here TDS-Belastungen im UF-Kreislauf, bietet aber kein Potenzial zur Steigerung der N{\"a}hrstoffdurchs{\"a}tze. Dies gilt auch f{\"u}r den Einsatz einer 300 kDa-Variante, im Vergleich zur priorisierten 150 kDa-UF-Membran. Mit der Hydropresse kann eine h{\"o}here Feststoffabscheidung wie mit Verstopfungs- bzw. Siebfiltrationen erreicht werden, die TDS-Belastungen sind im Retentat auf 5.000 - 7.000 ppm limitiert, oder m{\"u}ssen durch Verd{\"u}nnung auf diese Werte eingegrenzt werden. Mit der zus{\"a}tzlichen Anwendung einer Gassp{\"u}lung in der Anstr{\"o}mung der UF-Module, k{\"o}nnen TDS-Belastungen {\"u}ber 10.000 ppm erstmals dauerhaft bew{\"a}ltigt werden. {\"U}ber die so erweiterte Verfahrenstechnik sind Standzeiten von mehreren Wochen, ohne betrieblich bedingte Unterbrechungen, m{\"o}glich. Die durch Fluoreszenzmikroskopie nachweisbare Anreicherung von Methanbildnern im Retentat, best{\"a}tigt eine m{\"o}gliche Anwendung des Retentats als Biogassubstraterg{\"a}nzung. Der Biogasertrag wird durch Zusatz von Retentat zu den bisher verf{\"u}gbaren Substraten generell erh{\"o}ht. Eine Mischung aus Retentat und dem Feststoff aus der Hydropresse unterst{\"u}tzen die biochemische Stabilisierung in Fermentern. In Kombination mit Anteilen an Feststoff ist das Permeat bei der Bewertung von pflanzenbaulichen Ertr{\"a}gen, als konkurrenzf{\"a}hig zu Rohg{\"u}lle und Mineralstoffd{\"u}nger einzustufen. Das auf landwirtschaftliche Fl{\"a}chen ausgebrachte Permeat ist geruchslos.}, subject = {N{\"a}hrstoffsplitting; Nutrient splitting; Membranfiltration; Membrane filtration; Wirtschaftsd{\"u}nger; Farm fertilizer; Klimaschutz; Climate protection; Umweltschutz; Environment protection; Membranfilter; Wirtschaftsd{\"u}nger; Technikumsanlage; Klimaschutz}, language = {de} } @phdthesis{Andreessen2023, author = {Andreeßen, Lena M.}, title = {Towards real-world applicability of neuroadaptive technologies : investigating subject-independence, task-independence and versatility of passive brain-computer interfaces}, doi = {10.26127/BTUOpen-6652}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-66521}, school = {BTU Cottbus - Senftenberg}, year = {2023}, abstract = {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.}, subject = {Passive brain-computer interfaces; Mental state assessment; Neuroadaptive technology; Human-machine interaction; Electroencephalography; Passive Gehirn-Computer-Schnittstellen; Neuroadaptive Technologie; Mensch-Maschine-Interaktion; Elektroenzephalographie; Erfassung mentaler Zust{\"a}nde; Elektroencephalographie; Hirnfunktion; Mensch-Maschine-Interaktion; Gehirn-Computer-Schnittstelle}, language = {en} } @phdthesis{Andrei2018, author = {Andrei, Andreea Cristina}, title = {Untersuchung und Optimierung robuster und hochlinearer rauscharmer Verst{\"a}rker in GaN-Technologie}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-44782}, school = {BTU Cottbus - Senftenberg}, year = {2018}, abstract = {Die n{\"a}chste Generation von integrierten Sende- und Empfangsystemen erfordert sowohl robuste rauscharme Verst{\"a}rker als auch Leistungsverst{\"a}rker 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 f{\"u}r die Realisierung solcher Systeme ist. Diese Arbeit besch{\"a}ftigt sich mit hochlinearen und robusten rauscharmen Verst{\"a}rkern, welche in Sender-Empf{\"a}nger-Systeme integriert werden k{\"o}nnen. Zuerst wird der GaN HEMT charakterisiert. Die Eigenschaften von Transistoren werden w{\"a}hrend des Burn-in Prozesses und gepulster Anregung mit hoher {\"U}berlast am Eingang analysiert. Damit werden die Grundlagen f{\"u}r das Verst{\"a}ndnis des Verhaltens eines Verst{\"a}rkers w{\"a}hrend und nach der {\"U}bersteuerung am Eingang gelegt. Der Hauptteil dieser Arbeit zeigt die Entwicklung und die Charakterisierung von robusten rauscharmen Verst{\"a}rkern. Dar{\"u}ber hinaus wird ein neues Konzept f{\"u}r die Steigerung der Robustheit entwickelt, gemessen und charakterisiert. Das Konzept verwendet eine neuartige Zusammenschaltung zweier Transistoren am Verst{\"a}rkereingang, wodurch die Spannungsfestigkeit gegen{\"u}ber hohen Leistungspegeln gesteigert wird. Damit konnten H{\"o}chstwerte von +44dBm mit CW-Anregung und +47dBm mit gepulster Anregung am Verst{\"a}rkereingang ohne Besch{\"a}digung demonstriert werden.}, subject = {GaN HEMT; Rauscharme Verst{\"a}rker; Robustheit; Stacked Verst{\"a}rker; {\"U}bersteuerung mit hoher Eingangsleistung; GaN HEMT; Low noise amplifier; Ruggedness; Stacked amplifier; Input power overdrive; Rauscharmer Verst{\"a}rker; Galliumnitrid; HEMT; Robuste Regelung}, language = {de} } @phdthesis{AndredaRocha2012, author = {Andr{\´e} da Rocha, Andreza}, title = {The Birth of Brazilianism : the stereotypical representation of Brazil in the context of cultural imperialism and media concentration}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-27288}, school = {BTU Cottbus - Senftenberg}, year = {2012}, abstract = {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 {\´A}lvares 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.}, subject = {Brasilien; Postkolonialismus; Filmanalyse; Stereotyp; Postkolonialismus; Medienkonzentration; Stereotype; Filmanalyse; NWICO; Postcolonialism; Media concentration; Stereotypes; Film analysis; NWICO}, language = {en} } @phdthesis{Angwafo2006, author = {Angwafo, Tsi Evaristus}, title = {Status of wildlife and its utilisation in Faro and Benou{\´e} National Parks North Cameroon : Case study of the Derby Eland (Taurotragus derbianus gigas Gray, 1947) and the African Wild Dog (Lycaon pictus Temminck, 1840)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-111}, school = {BTU Cottbus - Senftenberg}, year = {2006}, abstract = {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 Benou{\´e} 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 Benou{\´e} National Parks were drawn to show their distribution. Eleven different wildlife species were studied in Faro and Benou{\´e} National park. The density of Kobus kob in Faro was 0.39 animals/km² and 0.28 animals/km² in Benou{\´e} and that for Acelaphus buselaphus was 0.4 animals/km² in Benou{\´e} 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 Benou{\´e} it was higher ranging from 0.03 - 0.87. The highest encounter rate was from Benou{\´e} 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 Benou{\´e} 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 Benou{\´e} 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 Benou{\´e}) 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 Benou{\´e} 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 Benou{\´e} National Parks respectively. Taurotragus derbianus gigas had the highest value of 19,400 Euros in Faro National Park and 87,000 Euros in Benou{\´e} National Park. Both parks contribute 0.58\% of the total revenue generated by wildlife in Faro and Benou{\´e}. 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).}, subject = {Kamerun; Nationalpark; Wildtiere; Wildbestand; Cameroon; National park; Wildlife population}, language = {en} } @phdthesis{Antoshkiv2007, author = {Antoshkiv, Oleksiy}, title = {Untersuchung der Z{\"u}ndung in einer neuartigen gestuften Brennkammer}, isbn = {978-966-603-540-3}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-3739}, school = {BTU Cottbus - Senftenberg}, year = {2007}, abstract = {Im Rahmen dieser Arbeit wurden die Z{\"u}ndungseigenschaften einer neuartigen Brennkammer untersucht, wobei auch das Magerverl{\"o}schverhalten mit in Betracht gezogen wurde. Die Untersuchungen der Z{\"u}ndbarkeit basieren auf den Ergebnissen numerischer Simulationen und anschließenden Auswertungen in einer Z{\"u}ndsubroutine. Die Ergebnisse der Str{\"o}mungssimulationen sind mit PIV-Messungen experimentell validiert worden, wobei die simulierten Sprayformen durch die ermittelten Mie-Aufnahmen best{\"a}tigt wurden. Hochgeschwindigkeitskamera - Aufnahmen wurden zur Validierung der berechneten minimalen Z{\"u}ndenergien verwendet. Die vorgenommenen Korrelationen zwischen den kalkulierten Werten der minimalen Z{\"u}ndenergie sowie den gemessenen AFR-Z{\"u}ndungsdaten er{\"o}ffnen einen Weg zur Bestimmung der zu erwartenden z{\"u}ndbaren Gemischkonzentrationen in realen Brennkammern aufgrund der simulierten minimalen Z{\"u}ndenergie. Im Rahmen der Arbeit wurde weiterhin eine Parametergewichtung durchgef{\"u}hrt, welche als Grundlage bei der Optimierung {\"a}hnlicher Brennkammern dienen kann.}, subject = {Triebwerk; Brennkammer; Z{\"u}ndung; Triebwerk; Brennkammer; Z{\"u}ndung; Aero engine; Combustor; Ignition}, language = {de} } @phdthesis{Antwi2009, author = {Antwi, Effah Kwabena}, title = {Integrating GIS and remote sensing for assessing the impact of disturbance on habitat diversity and land cover change in a post-mining landscape}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-7825}, school = {BTU Cottbus - Senftenberg}, year = {2009}, abstract = {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 S{\"u}d. 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 S{\"u}d 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 S{\"u}d 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 S{\"u}d 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.}, subject = {Landschaftsbewertung; Landschaftsanalyse; Fernerkundung; Geoinformationssystem; GIS; Fernerkundung; Landschaft; Fragmentierung; Reklamation; GIS; Remote sensing; Landscape; Fragmentation; Reclamation}, language = {en} } @phdthesis{Apau2017, author = {Apau, Kwaku Boakye}, title = {Developing a conceptual solution for domestic wastewater management in developing countries: Kumasi (Ghana) as a case study}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-41544}, school = {BTU Cottbus - Senftenberg}, year = {2017}, abstract = {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.}, subject = {Wastewater treatment; Treatment efficiency; Land requirement; Multi-attribute decision making; Assessment indicators; Behandlungseffizienz; Bodenbedarf; Abwasserbehandlung; Entscheidungsfindung f{\"u}r Mehrfachattribute; Bewertungsindikatoren; Entwicklungsl{\"a}nder; Abwasserreinigung; Umweltbewertung}, language = {en} } @phdthesis{Apte2020, author = {Apte, Anisha}, title = {A new analytical design method of ultra-low-noise voltage controlled VHF crystal oscillators and it's validation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-51386}, school = {BTU Cottbus - Senftenberg}, year = {2020}, abstract = {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.}, subject = {Quartz crystal; Crystal oscillator; Phase noise; Reference source; Voltage controlled; Quarzkristall; Kristalloszillator; Phasenrauschen; Referenzquelle; Spannungsgesteuert; Quarzoszillator; UKW; CAD}, language = {en} }