Refine
Document Type
- Doctoral thesis (22)
- Conference proceeding (5)
- Master thesis (3)
- Working paper (3)
- Report (2)
- Scientific article (1)
- Book (1)
Is part of the Bibliography
- no (37)
Year of publication
- 2020 (37) (remove)
Language
- English (37) (remove)
Keywords
- Kulturerbe (4)
- Cultural heritage (3)
- Energieressourcen (3)
- Energy resources (3)
- Conservation (2)
- Denkmalpflege (2)
- Denkmalschutz (2)
- Elektrische Energie (2)
- Energiequalität (2)
- Energietechnik (2)
- Energieversorgung (2)
- Energievorrat (2)
- Energiewende (2)
- Energy system transformation (2)
- Environmental management (2)
- Funktionseinheit (2)
- Iran (2)
- Laufzeit (2)
- Logistik (2)
- Metallspritzguss (2)
- Mixed-criticality (2)
- Mixed-integer programming (2)
- Nachhaltigkeit (2)
- Naturschutz (2)
- Power quality (2)
- Reconfiguration (2)
- Rekonfiguration (2)
- Titan (2)
- Titanium (2)
- Titanlegierung (2)
- Umweltbezogenes Management (2)
- Umweltmanagement (2)
- ATLAS (1)
- ATLAS <Teilchendetektor> (1)
- Abscheider (1)
- Agroforestry (1)
- Agroforstwirtschaft (1)
- Aleppo (1)
- Alkali PDT (1)
- Alkali-Nachbehandlungen (1)
- Alkalien (1)
- Alley cropping (1)
- Antioxidans (1)
- Architectural conservation (1)
- Architektur (1)
- Asteroidal triples (1)
- Asteroidale Tripel (1)
- Authenticity (1)
- Authentizität (1)
- Basar (1)
- Beirut (1)
- Bergbau (1)
- Bergbauentwicklung (1)
- Bestandsmanagement (1)
- Bewertungssystem (1)
- Bilevel optimization (1)
- Bioactivity (1)
- Bioaktive Verbindung (1)
- Bioaktivität (1)
- Biodiversity conservation (1)
- Biodiversität (1)
- Biodiversitätsschutz (1)
- Biomass (1)
- Biomasse (1)
- Biomaterial (1)
- Biomedical (1)
- Biomedizin (1)
- Box orientation (1)
- Branch-and-Bound (1)
- Branch-and-Bound-Methode (1)
- Branch-and-bound (1)
- Breitband-Empfänger (1)
- Breitbandempfänger (1)
- Broadband receiver (1)
- Bruchverhalten (1)
- CAD (1)
- CIGSe (1)
- Carbide (1)
- Catchment with data-scarcity (1)
- Center of gravity deviation (1)
- Climate change (1)
- Communication protocols (1)
- Composite/metal hybrids (1)
- Container (1)
- Container packing problem (1)
- Convex geometry (1)
- Cost-effectiveness (1)
- Creep resistance (1)
- Crystal (1)
- Crystal oscillator (1)
- Cultural landscapes (1)
- Cultural significance (1)
- Datenarme Einzugsgebiete (1)
- Decarbonisation (1)
- Dekarbonisierung (1)
- Determinanten (1)
- Determinants (1)
- Digital Shadow (1)
- Digital Twin (1)
- Digitaler Zwilling (1)
- District heating (1)
- Drahtlos (1)
- Drahtlose Kommunikation (1)
- Drahtloses lokales Netz (1)
- Dresden (1)
- EHD (1)
- Ecological–economic modelling (1)
- Effizienz (1)
- Effizienz der Landnutzung (1)
- Eigenfertigung-oder-Fremdbezug (1)
- Elektrohydrodynamik (1)
- End2End100 (1)
- Energieeffizienz (1)
- Energieeinsparung (1)
- Energiemanagement (1)
- Energy efficiency (1)
- Energy management (1)
- Erbe (1)
- Erhaltung des kulturellen Erbes (1)
- Erneuerbare Energien (1)
- Europa (1)
- Faser-Metall-Laminate (FML) (1)
- Faserverstärkter Kunststoff (1)
- Fehlererkennung (1)
- Fernwärme (1)
- Fernwärmeversorgung (1)
- Fibre metal laminates (FML) (1)
- Fine-grained (1)
- Flexible Fertigung (1)
- Flexible Manufacturing (1)
- Florenz (1)
- Food packaging (1)
- Forced convection (1)
- Fossil-free district heating (1)
- Fossil-freie Fernwärme (1)
- Fracture (1)
- Fraktur (1)
- Freiburg (1)
- Functional units (1)
- Fundamentallösungsmethode (1)
- Fügen (1)
- Fügetechnologie (1)
- GIS-based analysis of district heating potential (1)
- GIS-basierte Analyse von Fernwärmepotenzial (1)
- Ganzzahlige Optimierung (1)
- Gasphase (1)
- Gasphasenreaktion (1)
- Gemischt-ganzzahlige Optimierung (1)
- Geschichte 1860-1888 (1)
- Gilde (1)
- Gilden des Basars (1)
- Graph (1)
- Graph convexity (1)
- Graph refinement (1)
- Graph searching (1)
- Graphensuche (1)
- Graphenverfeinerung (1)
- Green hydrogen (1)
- Grenzfläche (1)
- Grenzflächen (1)
- Grundlösung (1)
- Grüner Wasserstoff (1)
- Guilds of Bazaar (1)
- Hardware-in-the-loop (1)
- Heritage (1)
- Heritage Preservation (1)
- Hindernisproblem (1)
- Hochgeschwindigkeitskommunikation (1)
- Hydrogen economy (1)
- Hydrological modeling (1)
- Hydrologische Modellierung (1)
- ITk (1)
- Industrie 4.0 (1)
- Industry 4.0 (1)
- Injection repair (1)
- Injektionsreparatur (1)
- Interface (1)
- Inverse optimal control (1)
- Inverse optimale Steuerung (1)
- Inverses Streuproblem (1)
- Isothermal aging (1)
- Isotherme Alterung (1)
- Italien (1)
- Italy (1)
- Joining technology (1)
- Karbid (1)
- Kaufverhalten (1)
- Klein- und Mittelbetrieb (1)
- Klimawandel (1)
- Kommunikationsprotokoll (1)
- Kommunikationsprotokolle (1)
- Komposite/Metall-Hybride (1)
- Konvexe Geometrie (1)
- Konvexität (1)
- Kosten-Effizienz (1)
- Kriechbeständigkeit (1)
- Kriechfestigkeit (1)
- Kristall (1)
- Kristalloszillator (1)
- Kulturelle Werte (1)
- Kulturelles Erbe (1)
- Kulturgüterschutz (1)
- Kulturlandschaft (1)
- Kulturlandschaften (1)
- Kunststoffverpackung (1)
- Kürzeste Wege Problem mit Zeitfenstern (1)
- Kürzester-Weg-Problem (1)
- LHC (1)
- Labeling (1)
- Labelling (1)
- Lagermanagement (1)
- Laminat (1)
- Land-use efficiency (1)
- Lausitz (1)
- Lebensmittelverpackungen (1)
- Leichtbaukonstruktion (1)
- Lichtbogen (1)
- Lightweight construction (1)
- Lignin (1)
- Lineare Knotenordnung (1)
- Lineare Optimierung (1)
- Logisitcs (1)
- London (1)
- Lusatia (1)
- MMC (1)
- Make or buy (1)
- Make-or-buy decision (1)
- Management (1)
- Management planning (1)
- Managementplanung (1)
- Mangan (1)
- Mangane (1)
- Manganlegierung (1)
- Marginalisation (1)
- Marginalisierung (1)
- Materialität (1)
- Mathematische Modellierung (1)
- Mediterranean (1)
- Mehrkriterielle Optimierung (1)
- Metal injection moulding (1)
- Metal-Injection-Molding (1)
- Metallhalogenide (1)
- Metallischer Werkstoff (1)
- Metallmatrix-Verbundwerkstoff (1)
- Method of fundamental solutions (1)
- Mining development (1)
- Mittelmeerraum (1)
- Mode of governance (1)
- Modell (1)
- Modular redundancy (1)
- Molybdänhalogenide (1)
- Muharram (1)
- Multi-objective calibration (1)
- Multikriterielle Kalibrierung (1)
- Nachhaltiger Konsum (1)
- Naturschutzorganisation (1)
- Niob (1)
- Niobium (1)
- Nioblegierung (1)
- Nitrogen load simulation (1)
- Non-overlapping (1)
- Numerische Strömungssimulation (1)
- ODT (1)
- Oberfläche (1)
- Oberflächen (1)
- Obstacle problem (1)
- Operations Research (1)
- Operations research (1)
- Optimal control (1)
- Optimale Kontrolle (1)
- Optimale Steuerung (1)
- Optimality conditions (1)
- Optimalitätsbedingung (1)
- Optimalitätsbedingungen (1)
- Optimierungsproblem (1)
- Oxygen (1)
- PHY layer (1)
- PSSS (1)
- Passive design (1)
- Passives Design (1)
- Pflanzenwachstum (1)
- Pflanzlicher Rohstoff (1)
- Phase noise (1)
- Phasenrauschen (1)
- Piezoresistivity (1)
- Piezowiderstand (1)
- Post-Konflikt-Wiederaufbau (1)
- Post-conflict reconstruction (1)
- Power-to-Gas (1)
- Power-to-gas (1)
- Prediction uncertainty (1)
- Problem des Handlungsreisenden mit Zeitfenstern (1)
- Prostitution (1)
- Protokollverarbeitung <Kommunikationstechnik> (1)
- Purchase behaviour (1)
- Quantitative empirical methods (1)
- Quantitative empirische Methoden (1)
- Quartz crystal (1)
- Quarzkristall (1)
- Quarzoszillator (1)
- Redundanz <Informatik> (1)
- Reference source (1)
- Referenzquelle (1)
- Regional economic potential (1)
- Regionalökonomisches Potenzial von Fernwärme (1)
- Ressourceneffizienz (1)
- Rollers (1)
- Roter Fluss (1)
- Run-Time (1)
- Run-time (1)
- Russian-European energy system (1)
- Russisch-Europäisches Energiesystem (1)
- Russland (1)
- Rutheniumhalogenide (1)
- SME (1)
- SWAT< Software> (1)
- Sauerstoff (1)
- Scenario generation (1)
- Schichtverbundwerkstoff (1)
- Schmelzen (1)
- Sensor (1)
- Sensormodul (1)
- Sex work (1)
- Sexarbeit (1)
- Sexualverhalten (1)
- Shortest path problem with time-windows (1)
- Silicium (1)
- Silicon (1)
- Silizium (1)
- Simulation (1)
- Simulation der Stickstoffbelastung (1)
- Solararchitektur (1)
- Solarzelle (1)
- Spannungsgesteuert (1)
- Spatial history (1)
- Stadt (1)
- Stadtentwicklung (1)
- Stadtsoziologie (1)
- Stari Most (Mostar) (1)
- Statistics (1)
- Statistik (1)
- Steuerungsmodus (1)
- Stickstoffbelastung (1)
- Stochastische Optimierung (1)
- Stream processing (1)
- Stress (1)
- Stromverarbeitung (1)
- Städtebau (1)
- Submillimeter-wave (1)
- Submillimeterwelle (1)
- Subsaharisches Afrika (1)
- Superalloys (1)
- Superlegierung (1)
- Superlegierungen (1)
- Surface (1)
- Sustainable (1)
- Sustainable consumption (1)
- Synthese (1)
- Syntheseplanung (1)
- Synthesis (1)
- Syria (1)
- Syrien (1)
- Szenario-Erzeugung (1)
- THz (1)
- Tattoo (1)
- Teheran (1)
- Tehran (1)
- Terahertzbereich (1)
- Thermodynamic (1)
- Thermodynamik (1)
- TiC (1)
- Titancarbid (1)
- Tragrollen (1)
- Transmission <Physik> (1)
- Transmission eigenvalues (1)
- Transmissionseigenwerte (1)
- Travelling salesman problem with time-windows (1)
- Travelling-salesman-Problem (1)
- Tuchmacher (1)
- Turbulente Strömung (1)
- Turbulenzmodell (1)
- Two-stage stochastic optimization (1)
- Tätowierung (1)
- UKW (1)
- Ultra high speed communication systems (1)
- Ultra-Hoch-Geschwindigkeits-Kommunikationssysteme (1)
- Uncertainty (1)
- Unsicherheit (1)
- Unternehmensforschung (1)
- Urbanscape (1)
- Vapor phase (1)
- Vernacular architecture (1)
- Vernakuläre Architektur (1)
- Vertex order characterisation (1)
- Voltage controlled (1)
- Vorhersageunsicherheit (1)
- Warehouse management (1)
- Wasserherkunftsgebiet (1)
- Wasserstoffwirtschaft (1)
- Welterbe (1)
- Weltkulturerbe (1)
- Wiederaufbau (1)
- Wireless (1)
- Wireless communication (1)
- World Heritage (1)
- Wärmebedarf (1)
- Yellow hydrogen (1)
- Yield-SAFE (1)
- Zwei-Ebenen-Optimierung (1)
- Zweistufige stochastische Optimierung (1)
- Ökologisch-ökonomische Modellierung (1)
- Übergangsmetallverbindungen (1)
Institute
- FG Denkmalpflege (3)
- FG Ingenieurmathematik und Numerik der Optimierung (3)
- FG Mikrostrukturelles Werkstoffdesign (3)
- FG Verteilte Systeme und Betriebssysteme (3)
- FG Energieverteilung und Hochspannungstechnik (2)
- FG Angewandte Mathematik (1)
- FG Anorganische Chemie (1)
- FG Automatisierungstechnik (1)
- FG Bodenschutz und Rekultivierung (1)
- FG Computational Physics (1)
In the time of increased awareness about the environment problems by the public opinion and also intensive international efforts to reduce emissions of greenhouse gases, as well increase of the generation of electrical energy to facilitate industrial growth, the conference offers broad contribution towards achieving the goals of diversification and sustainable development.
Focus of the student conference is to promote the discussion of views from scientists and students from Wroclaw University of Technology, Technical University of Ostrava and Brandenburg University of Technology Cottbus-Senftenberg.
The conference offers prominent academics and industrial practitioners from all over the world the forum for discussion about the future of electrical energy and environmental issues and presents a base for identifying directions for continuation of research.
In the time of increased awareness about the environment problems by the public opinion and also intensive international efforts to reduce emissions of greenhouse gases, as well increase of the generation of electrical energy to facilitate industrial growth, the conference offers broad contribution towards achieving the goals of diversification and sustainable development.
Focus of the student conference is to promote the discussion of views from scientists and students from Wroclaw University of Technology, Technical University of Ostrava and Brandenburg University of Technology Cottbus-Senftenberg.
The conference offers prominent academics and industrial practitioners from all over the world the forum for discussion about the future of electrical energy and environmental issues and presents a base for identifying directions for continuation of research.
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.
We address the single container packing problem of a company that has to serve its customers by first placing the products in boxes and then loading the boxes into a container. We approach the problem by developing and solving mixed-integer linear models. Our models consider geometric constraints that feature non-overlapping constraints, box orientation constraints, dimensionality constraints, relative packing position constraints, and linearity constraints. We also develop an extension of the models by integrating load balance and the deviation of the center of gravity. We tested the models on a broad set of real instances involving up to 41 boxes and obtained optimal solutions in most cases and very small gaps when optimality could not be proven.
An empirical and simulation-based assessment of tree growth in temperate alley-cropping systems
(2020)
The potential of biomass generated from dedicated energy crops, used in short-rotation coppices (SRC), progressively grows recognition as a flexible primary source for the generation of energy, heat, fuel, and bio-based materials and chemicals. The alley-cropping systems (ACSs), which can integrate tree strips managed as SRC into agriculturally managed fields, are often regarded as an adaptable multi-crop land-use strategy that can provide ecological and economic benefits. The research aim of the present dissertation has focused on investigating the prospective implications of different site-specific conditions and scenarios on tree growth in ACSs with SRC, thus incorporating several experimental and simulation-based studies. For this, the ability of a process-oriented, eco-physiological tree growth model was investigated in order to (i) impute missing empirical data, thus securing a reliable repository of tree growth characteristics, (ii) simulate the tree growth in terms of woody biomass production in strong relation to the interactions with adjacent crops and their respective resource capture, (iii) predict and evaluate the tree growth sensitivity to prospective climate changes, thus performing risk assessments for the near and distant future, and (iv) derive and assess the land equivalent ratio (LER) and gross energy yield for different climatic, soil, and management scenarios. The findings have corroborated the potential tree growth vulnerability to prospective climatic changes, particularly to changes in water availability, and have underlined the importance of coping management strategies in SRC for forthcoming risk assessments and adaptation scenarios. Both LER and gross energy yields had resulted in a convex curve where the maximum values were achieved when either the tree or crop component was dominant (>75% of the land area) and minimum when these components shared similar proportions of land area. Collectively, the implications of different site-specific conditions and scenarios on tree growth in ACSs with SRC have been investigated in order to improve the decision-making, optimization, and adaptation of such systems. Last but not least, this dissertation has emphasized the considerable potential of modelling approaches in ACSs, as they can impute missing data from scarce available data and simulate tree and crop yields for specific site-conditions in a non-intrusive, inexpensive, and prompt way while supporting early site-setup planning.
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.
This thesis is an attempt to assess some of the effects that electroquasistatic body forces exert on turbulent internally forced convective flows. In order to do that, a stochastic turbulence model is employed, namely, the One-Dimensional Turbulence (ODT) model.
The reduced dimensionality of ODT demands a reduction of the Navier-Stokes equations (and in this case, also the Maxwell equations), into a 1-D system. This is done by performing an asymptotic analysis in terms of the nondimensional numbers of the flow. Also, a validation step due to the relative novel character of the cylindrical ODT formulation is done for an incompressible and constant properties flow regime and a variable density flow regime. The validation is presented for both the temporal (T-ODT) and a novel spatial (S-ODT) formulation in both planar and cylindrical geometries. Results in the constant property case show that wall normal (and radial) profiles, in both the T-ODT and S-ODT formulations, show good agreement with each other and to the data of Direct Numerical Simulations (DNSs). For the evaluated variable density heated pipe flow, gradients at the wall can be better reproduced with S-ODT.
After validating the model, ODT is applied first into a planar configuration which emulates the flow in a wire-plate Electrostatic Precipitator (ESP). For this flow, the additional input energy due to the electroquasistatic body force has an effect on the modification of the bulk velocity, and subsequently, the skin friction coefficient. Some qualitative DNS trends are confirmed with ODT, such as the localized increase of the Reynolds stress, as a consequence of increased eddy activity close to the discharge electrodes. Next, the results of ODT simulations in a cylindrical wire-tube ESP are presented. Here, ODT results are compared to experimental results. ODT results for global integral quantities such as the streamwise pressure gradient and the Nusselt number enhancement ratio are able to match in a reasonable way the experimental results. The competing relevance between the EHD contribution to turbulence by momentum, and by affecting the temperature and density due to the Joule heating effect is also analyzed, showing the leading order relevance of the former one. Specifically for the Nusselt number results, the sensitivity of the EHD flow to transition effects is shown to be very significant.
This thesis may open the door to a vast new field of phenomena which can not only serve for the further validation of the ODT model against DNSs or experiments, but also for the real use of ODT in applications which are so far inaccessible for traditional DNSs.
In the last 30 years, communication became one of the most important pillars of our civilization. Every day terabytes of information are moved wired and wireless between computers. In order to transport this amount of data, researchers and industry increase the data rates of the underlying communication networks with impressive speed. However, such ultra-high data rates are unavailable at the communication endpoints.
One reason why ultra-high data rates are still not available for the communication endpoints is their inability to handle the protocol processing at this data rate. In order to enable communication endpoints to process high-volume data streams, the protocol processing has to be parallelized and optimized on all processing levels. However, parallelization and optimization are cumbersome tasks, which are further complicated as the protocol processing is traditionally carried out by the operating system.
This thesis aims at circumventing these problems by moving the protocol processing into external processing hardware and interpreting communication protocols as stream processing problems. In order to achieve ultra-high data rates at the communication endpoints, a protocol stream processing design approach was developed and evaluated. The design process is separated into implementation, soft real-time analysis, parallelization, and mapping steps, which allow a scalable protocol implementation without paradigm changes. Furthermore, a data link protocol for 100 Gbit/s wireless was developed and implemented with the new stream processing design concept, in order to show its feasibility. The data link protocol is configurable for different communication conditions and easy to parallelize by providing different granularities of packets. The proposed design-process has shown to be suitable for uncovering bottlenecks and helping with debugging the individual stages of the protocol.
One of the standard approaches for solving time-dependent discrete optimization problems, such as the travelling salesman problem with time-windows or the shortest path problem with time-windows is to derive a so-called time-indexed formulation. If the problem has an underlying structure that can be described by a graph, the time-indexed formulation is usually based on a different, extended graph, commonly referred to as the time-expanded graph. The time-expanded graph can often be derived in such a way that all time constraints are incorporated in its topology, and therefore algorithms for the corresponding time-independent variant become applicable. The downside of this approach is, that the sets of vertices and arcs of the time-expanded graph are much larger than the ones of the original graph. In recent works, however, it has been shown that for many practical applications a partial graph expansion, that might contain time infeasible paths, often suffices to find a proven optimal solution. These approaches, instead, iteratively refine the original graph and solve a relaxation of the time-expanded formulation in each iteration. When the solution of the current relaxation is time feasible an optimal solution can be derived from it and the algorithm terminates. In this work we present new ideas, that allow for the propagation of information about the optimal solution of a coarser graph to a more refined graph and show how these can be used in algorithms, which are based on graph refinement. More precisely we present a new algorithm for solving Mixed Integer Linear Program (MILP) formulations of time-dependent problems that allows for the graph refinement to be carried out during the exploration of the branch-and-bound tree instead of restarting whenever the optimal solution was found to be infeasible. For demonstrating the practical relevance of this algorithm we present numerical results on its application to the shortest path problem with time-windows and the traveling salesman problem with time-windows.
Climate change, CO2 reduction, resource efficiency are only 3 current keywords that describe the current industrial-economic situation. In order to influence climate change effectively, the conversion of supply systems with technically usable forms of energy must succeed in the next decade. The international network founded in Baku in 2015 bundles research activities in the broad field of energy supply and energy efficiency. Discuss current research approaches and results with scientists and experts from renowned universities and follow Azerbaijan's efforts to implement the energy revolution.
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.
The increasing demand for competitive, whilst also environment-friendly airplane travel, compels the design of highly efficient engines in the aeronautical field. A potential for improvement of traditional polycrystalline Ni-based superalloys, aiming higher creep resistance, was investigated. The approach adopted the concept of metal matrix composites (MMCs) to incorporate a rigid discontinuous phase, in the form of particles, to a γ’-strengthened Ni-based superalloy. In order to make the concept feasible, different microstructures resulting from diverse manufacturing techniques were investigated. By using distinct mixing and sintering methods, powders of Inconel X-750 and TiC were combined to form composites containing 15 vol.% of reinforcing particles. Powders were prepared with low and high energy milling processes, and formed by uniaxial pressure sintering and spark plasma sintering methods. Non-reinforced variants and composites had microstructures thoroughly examined at their initial state and after long isothermal aging treatments. Selected variants were further submitted to tensile and compression creep tests at temperatures between 700 and 800 °C, in the stress range of 200 to 500 MPa.
A comprehensive analysis was conducted using techniques such as EBSD, XRD Rietveld refinement, EDS and TEM to evaluate the development of γ’, η and TiC phases, determining the achievable microstructures with each fabrication method and establishing their evolution after aging treatments over times up to 1000 h. Likewise, creep properties were analyzed by obtaining parameters such as creep exponents, threshold stresses and activation energies. A creep life estimation was conducted with the use of a Monkman-Grant relationship and a Larson-Miller parametrization. Lastly, the potential for a reduction in creep strain rates in a working turbine blade, considering the density of investigated materials as a parameter, was evaluated.
All produced composites presented power law creep, with dislocations surpassing γ’ particles by climb. The variant produced by high energy ball milling and spark plasma sintering exhibited the highest creep rates, resulting from intense diffusion through grain boundaries. It also presented η phase after long isothermal aging, which affects negatively the creep resistance. Contrastingly, in the variant produced by low mixing combined with pressure sintering the lowest creep rates were observed. It was proposed that reinforcing TiC particles effectively acted as a load bearing phase, counterbalancing the adverse effects of the intergranular diffusion in the refined microstructure. Furthermore, a higher microstructural stability was observed in this variant, resulting from limited interaction between TiC particles and the matrix during fabrication.
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.
The powder metallurgically produced beta titanium alloys (traditional PM beta Ti-alloys) have long been plagued by high impurities contamination. For binder-based powder technologies, they originate from the sintering atmosphere, the debinding processes and the starting powders. In general, a normal carbon residual of binder-based powder technologies is capable of incurring the formation of aligned TiCx particles along beta grain boundaries (GB-TiCx) in most classes of beta Ti-alloys. Whereas, oxygen atoms are likely to deteriorate the ductility of PM Ti alloys by promoting the formation of diverse brittle phases and/or altering the deformation modes. Such materials exhibiting rather low toughness to strain ratios are not an option for critical structural applications, where catastrophic damage is completely unacceptable.
In this study, biotolerant metastable beta Ti-20Nb-10Zr alloys, containing a certain amount of carbon, oxygen residuals originated from materials processing and consequently 0.5 vol.% in situ synthesized TiCx particles, were fabricated via metal-injection-molding (MIM). With varying yttrium (Y) addition, the effects of Y-induced oxygen scavenging, beta-grain refinement and porosity increment on tensile properties were systematically investigated. To scavenge oxygen from the beta Ti-matrix, the Y elemental powder with a maximum particle size of 15 µm (e.g. <12 µm or 1200 mesh) is more appropriate than the commonly used <45 µm (i.e. 325 mesh) sized powder or larger ones and without significant detrimental effect on the as-sintered density of beta Ti-alloys.
A novel toughening strategy was proposed by regulating TiCx precipitation evolution and resultantly adjusting particles distribution pattern. Synchrotron radiation identified that two separate TiCx precipitation-type reactions occurred at the beta phase region and the alpha/beta region. In a narrow temperature range between these two precipitation reactions, dissolution of carbides was observed just below alpha/beta transus. Y addition can postpone TiCx precipitation. On the basis of those mechanisms, adjusting TiCx particle distribution was proposed for the first time, specifically a combination of yttrium addition (Y) and carbide spheroidization reprecipitation annealing (CSRA). As a result, aligned GB-TiCx particles were adjusted to dispersed intragranular TiCx particles. An apparent toughening effect (≈ 113% increment reaching elongation = 8.3%) was achieved after TiCx redistribution, while non-optimally aligned TiCx pattern seriously limited tensile toughness of materials. Here, the mechanisms of TiCx redistribution behavior and its toughening are elucidated systematically.
Process-based hydrological models, which simulate nitrogen load from its sources to the receiving waterbody, play an important role in supporting catchment management. The reliability of those models, such as the representative model SWAT used in this study, is determined by a sound calibration and the analysis of the prediction uncertainty. The multi-objective calibration approach prevails the classic single-objective calibration on the spatial parameterization of specific processes. However, the requirement of additional observations and practical procedures limits its application. Moreover, the prediction uncertainty of nitrogen load is inevitable and should also be quantified. This study is a scientific contribution to catchment management by overcoming the challenge with a systematic, well-founded concept of multi-objective calibration and uncertainty analysis for nitrogen load simulation in data-scarce catchments. The concept is tested and proofed by its practical applicability on the Yuan River Catchment (YRC) in China and leads to a generalized, recommended procedure for catchment management application as valuable progress in this field.
The study proposed to apply three groups of objectives, multi-site, multi-objective-function, and multi-metric. The applicability and the advantages of two multi-objective calibration approaches, Euclidean Distance and Non-Dominated Sorting Genetic Algorithm-II were analyzed. To quantify the prediction uncertainty, the study proposed to use the simulations with the highest or the lowest percent bias to represent the uncertainty band of the nitrogen load from the critical source areas (CSAs) and to the stream. The data-scarcity of the YRC was overcome by metrics obtained from open-access satellite-based datasets and metrics extracted from the existing discharge observations. Results show that multi-objective calibration has ensured the model’s better performance in terms of the spatial parameterization, the magnitude of the output time-series and the water balance components, in comparison to single-objective calibration. The predicted CSAs showed that 50% of the total nitrogen (TN) loading to the stream was from 26.3% to 37.1% of the area in the YRC. Meanwhile, over 50% of those TN were from the paddy field. Recommendations for application go to the multi-objective calibration considering all three groups of objectives. Approaches to obtain multi-metric objectives in the YRC are also applicable for catchments with data-scarcity. Recommendations for nitrogen management in the YRC is to emphasize the CSAs identified, especially the paddy field.
Tehran Bazaar has been the most influential marketplace in Iran, over the last two hundred years, since Tehran became the capital of the country. The Bazaar has been a significant socio-political agent in Iranian society. Nevertheless, less attention has been given to its internal atmosphere, where the bazaaris, have tried to conserve their traditions and preserve their heritage. One of these heritages are “hey’ats”, religious formations for holding mourning sessions in Muharram month, as a ritual in Shi’a Islam. “Hey’ats” give the guilds a sense of collective identity, they represent them, and also build a shared heritage for them.
The Drapers’ Guild was the first guild in Tehran Bazaar, founding a hey’at. They founded this hey’at in 1883 and named it “the Drapers’ Hey’at”. After the Islamic Revolution of 1979, the Drapers faced difficulties preserving their heritage. They were forced to displace the Mirza Mousa Mosque in the Bazaar. The Mosque was their center for holding religious sessions and was publicly known as “the Drapers’ Mosque”. Since they were attached to the Mosque, their displacement was perceived a loss of heritage. Later, they decided to build a new home, “the Drapers’ Hosseinieh”. They decided to implement the interior design of their lost Mosque in the new place. This strategy enabled them overcome “the traumatic experience of displacement and heritage loss.” Also, to safeguard their new place, they legally registered their hey’at as an institution, and they wrote a constitution for it. The attempts for modernization, led them to develop beneficiary activities, as well. In this research, a qualitative approach is applied, benefiting from multiple methodologies, including; ethnography, secondary sources, and visual methods. The researcher has attempted to outline the story of the Drapers in preserving their heritage. This study hopefully would be useful for similar traditional organizations, showing how continuity and heritage preservation are possible to achieve for communities having experienced a troubled past.
Architectural conservation is conventionally associated with preservation of buildings or ensembles that were seats of religious or secular power marking great architectural, political, or scientific accomplishments.
Dark and difficult heritage concerns events of disasters, extermination, and war. But what happens to stories and their places that do not fit into any of these categories? They are neither grand or beautiful, nor explicitly traumatic but nonetheless they embed cultural values and norms, or perhaps even the opposite of them: the bordellos and the marginalised groups of society that are usually disregarded in heritage discourses.
The question of sex work in contemporary culture holds an important place, as it is connected to social and economic rights of women. Historic sex work, and the places associated with it, imbed in this sense a contention value, because still today it provokes debate among different interest groups.
This research work presents the first in-depth study into the location of Florentine bordellos and sex workers between 1860 and 1888. It was a central moment in the history of these women and their trade because a new regulation on sex work was introduced by the recently unified Italian state which spatially controlled the sex trade. Each bordello and the sex workers came under intense scrutiny of the law. What was a dramatic development in the life of these women at the time, has allowed for extensive historical analysis.
The research draws primarily from over 5,000 archived police files and examines the location of sex trade in relation to the legal framework provided by the regulation known as the Regolamento Cavour. It was to ensure that sex workers would not pass on any venereal disease, while, at the same time, strived to maintain moral order in a continuously growing city, faced with urban development. In addition, the historic spatial development of bordellos within the perimeter of the ancient city walls was studied as well as the economic and political factors which influenced the position of a bordello within the urban fabric. For that purpose, the study incorporated information from historic city and street directories as well as cadastre maps. These different layers of information are conveyed in numerous maps to visualise the spatial context of and relation between sex work and spaces.
This thesis focuses on the investigation and characterization of the surfaces and interfaces of chalcopyrite-based Cu(In,Ga)Se2 (CIGSe) thin film solar cells using various x-ray and electron spectroscopies. In particular, the impact of alkali post deposition treatments (PDT) on the chemical and electronic surface and interface structure of CdS/CIGSe absorbers is studied.
The structure of “real world” CdS/CIGSe interfaces and how they are impacted by different alkali PDTs was investigated by a combination of different x-ray spectroscopies. The interface formation is characterized by studying sample sets with different CdS thicknesses. The chemical environment for indium and cadmium is revealed by deriving the modified Auger parameter α'(In) and α'(Cd) using the kinetic energy of most prominent Auger line together with the binding energy of the chosen core level. A more complex situation is found for CdS/CIGSe samples that underwent NaF+KF PDT, where a K-In-Se compound is initially present on top of the chalcopyrite absorber. The conversion of the K-In-Se type species into a Cd-In-(O,OH,S,Se) interface compound is recorded at short CBD-CdS deposition times. It appears the majority of K that is present at the surface of the NaF+KF PDT CIGSe absorber is dissolved in the CBD and partially re-deposited as K-O type species. The Cd/S ratio clearly deviates from the stoichiometry expected for CdS, and a Cd(O,OH,S)-like compound is likely formed. The electronic structure of CdS/CIGSe interface is similarly more complex for the NaF+KF PDT compared to the NaF PDT case, where only Cd(O,OH,S) buffer was formed.
In an attempt to shed more light into this complex situation, the impact of evaporated alkali metals (K, Rb, Cs) on the surface structure of CIGSe was studied in-system by synchrotron-based hard x- ray photoelectron spectroscopy (HAXPES), aiming at understanding the underlying mechanism of the interfacial effect of alkalis on the performance of CIGSe devices. In the case of K deposition, two K species are observed by x-ray absorption near-edge structure (XANES) and HAXPES, one of which species disappears at high annealing temperature. Furthermore, three new In contributions (In-O and K-In-Se, metallic In species) can be observed after K evaporation. The evolution of chemical contribution supports the formation of a K-In-Se and Cu-poor CIGSe (1:3:5) bilayer structure that is similar to what was reported for “real world” NaF+KF PDTs. Deposition of heavy alkali metals (Rb, Cs) induced the formation of alkali selenide phases after alkali evaporation and during low temperature annealing. Similar chemical changes as seen for the K composition (i.e. presence of metallic In, In-O, and alkali-O) are observed. However, detailed analysis of the Alk/Se ratio and composition provide direct evidence for the formation of a Alk-(In)-Se and (Cu,Alk)(In, Ga)Se2 bilayer.
The insights from these studies promise to provide crucial aid to fully exploit alkali pre-treatments in scientific and industrial CIGSe production, and will deliberate use of this means of surface/interface tailoring to push efficiencies even further.
The requirement for wireless communication with a speed beyond 100 Gbps is growing. There are mainly two possible approaches to achieve 100 Gbps system. One approach is to target lower transmission bandwidth and very high spectral efficiency. This method requires advanced digital signal processing operations, which are power-hungry. Another possible path is to go for a high-transmission bandwidth and a moderate spectral efficiency. We decided for this direction to implement a 100 Gbps system. We have chosen parallel sequence spread spectrum (PSSS) as an analog-friendly mixed-signal modulation where most of the baseband processing is in the analog domain, and only a small part is in the digital domain. For the channel equalization, we consider an “effective channel” that takes into account the wireless channel and the effects of the transmitter and receiver hardware impairments. The influence of the nonlinear channel response was analyzed for a PSSS modulated signal by employing the RAPP model for the power amplifier. For the first time, we performed a Hardware-In-The-loop experiment using PSSS modulation in the terahertz band. A PSSS modulated signal at a chip rate of 20 Gcps with spectral efficiency of 4 bit/s/Hz is transmitted using a 230 GHz RF-frontend operating in the linear range to achieve a data rate of 80 Gbps. One more important property is that the channel estimation and equalization are performed in the analog domain. A high-speed channel equalization algorithm was developed and implemented on FPGA/ASIC, which operates at(1/10)th of PSSS symbol rate. A parallel PSSS encoder transmitter architecture was designed to work at a high chip rate, and it was implemented on FPGA /ASIC and had an energy efficiency of 0.21 pJ bit−1 on 28nm ASIC.
In this Thesis, we put forward a case for the analog-friendly modulation scheme called PSSS. This scheme does not only modulates the signal but rather builds up an eco-system (such as channel estimation, equalization, and synchronization), which is responsible for the baseband operation.
Learning from the past, designing for the future : sustainability of the Mediterranean vernacular
(2020)
With climate change and the depleting ozone layer, awareness about protecting the environment is increasing and “Sustainable Architecture” is becoming an essential part of the architectural future of cities. However, sustainable buildings of today are being built with high cost, high tech systems which can be reduced by taking advantage of past technologies and systems. The brilliance of vernacular architecture and the way man adapted to his surroundings fascinated me and inspired me to do further research on the sustainable characteristics of vernacular settlements of the Mediterranean area in order to determine if these characteristics can be applied to present and future architecture in an innovative way to create sustainable buildings with least possible energy consumption.
The method of research was based upon a general analysis of the passive design (solar and wind) characteristics of a town or settlement in Mediterranean climate starting from its site elements such as topography, vegetation, water. After that its urban structure, such as the geometry, block and street orientation and dimensions. Following that, the dwelling characteristics like dwelling shape, orientation and dimensions and finally the thermal regulating elements found in these dwellings, such as windows and vegetation. These elements were given a score according to their contribution to energy savings in buildings. Four case studies were chosen: two vernacular case studies from the region of study (the Mediterranean Coasts) and two modern case studies inspired by the Mediterranean vernacular. The analysis was repeated in the same sequence mentioned: Site, Settlement, Dwelling, Element, for the actual performance of each case study. The elements were given a number of points out of the score assigned for each element in the general analysis.
A total score and rating for each case study resulted from this analysis. The objective of these scores were to compare the performance of the vernacular case studies to the vernacular inspired case studies in terms of energy savings. The final scores displayed comparable results between both types of case studies meaning that when these modern settlements were designed with an influence from the Mediterranean vernacular, their performance in energy savings was close to that of a vernacular settlement. That means that it is possible to design settlements which are influenced by vernacular settlements and can even defeat them by following the general guidelines of the vernacular passive design characteristics in addition to modern tools and innovative methods. These guidelines can be reflected in a handbook and rating system which can become a simple step by step guide for architects and planners to design sustainable settlements without the need for expensive and complicated rating systems and consultants.
The Digital Twin is seen as the step towards digitalization in many areas, including the area of manufacturing which is the focus of this paper. However, the frequently application-oriented development of concepts and initial implementations make it difficult to adapt them to other applications. Especially when production deviates from the usual highly automated processes and requires high flexibility, e.g. to allow batch size one. In such a case, the Digital Twin must support modular shopfloors with flexible areas in which different production times and various tools and machines are used. It should also be possible to react promptly to problems in production. Design errors that only become apparent during production must be reported directly. In order to deal with this problem, the paper presents a concept for an abstract representation of a Digital Shadow (DS). The DS combines the disciplines of production planning and control, product lifecycle and layout planning which creates new links and enables further application scenarios. Based on this Digital Shadow, different applications can be realized that provide user-related solutions. For this purpose, a tree structure is used that links information about the product and the production environment which in this case is variable.
Anthropogenic threat for the world’s environment and ecosystems and financial constraints necessitate a wise use of resources for the implementation of biodiversity conservation measures. A cost-effective planning and governance of biodiversity conservation has to be done to achieve maximal ecological outcomes with given financial resources. A better understanding of available modes of governance can help to improve the cost-effectiveness of biodiversity conservation planning and implementation.
This thesis investigates the influence of governance mode choice on the cost-effectiveness for biodiversity conservation measure implementation in selected conceptual and empirical settings, and identifies ecological, economic and climatic factors of influence. Linking the cost-effectiveness analysis for biodiversity conservation measures to the make-or-buy decision enables a novel perspective on cost-effective biodiversity conservation. In this context, conservation agencies are assumed to have two main options to implement biodiversity conservation measures in principle: (1) the buy alternative in which land is purchased for the purpose of biodiversity conservation measure implementation, and (2) the compensation alternative where a conservation agency compensates landowner’s opportunity costs to incentivise voluntary conservation measure implementation by landowners.
Two conceptual ecological-economic models were developed to analyse the cost-effective governance mode choice and their sensitivity to changing ecological, economic and climatic parameters. Two empirical case studies were conducted to address the question of cost-effective governance mode choice for a conservation project in Schleswig-Holstein (Germany) and a federal state wide comparison of conservation activities in California (USA).
It was found that the buy alternative is more cost-effective than the compensation alternative if conservation budgets and interest are high. In addition, not only the choice of governance mode is relevant with respect to cost-effectiveness, but also the mechanism to spatially select conservation sites chosen within a selected governance mode. Changing climate change speed – among other factors – influences the cost-effectiveness of governance modes and site selection strategies. The cost-effective governance mode choice also crucially depends on the intended timeframe of a conservation project. For shorter timeframes, compensating landowners is the cost-effective governance mode, however for longer durations the buy alternative becomes more cost-effective. This effect arises specifically due high one-off costs for buying land, which however amortize over time, compared to high recurring costs for compensating landowners. Based on these findings, the policy recommendations are provided which aim to improve the cost-effectiveness of governance modes available for biodiversity conservation.
Sub-Saharan African cultural landscapes are adversely impacted by various development pressures, which calls for a holistic and integrated approach in their management. Mining development has been ranked highly by UNESCO World Heritage Centre, as one of the most common factors threatening the conservation and management of World Heritage properties around the world. For instance, out of 141 World Heritage properties which submitted their state of conservation reports in 2015, 18% were affected by mining activities. Out of these, 84% of the properties that were threatened by mining development were either cultural landscapes, natural properties and or mixed properties. African World Heritage cultural landscapes are the ones highly affected and threatened by planned and on-going mining and exploration activities.
Therefore, research was carried out using the Mulanje Mountain Cultural Landscape of Malawi and Mapungubwe Cultural landscape of South Africa. Specifically, the study aimed at examining the existing cultural landscape management theories and concepts in order to understand the key elements to be integrated into the suggested strategic management planning methodological framework. It also aimed at evaluating the impact of mining development on the conservation and management of African cultural landscapes. The study also investigated the stakeholder’s views and perception about the impact of mining activities on cultural and natural heritage values of the landscapes.
To achieve the research objectives, the literature was reviewed, firstly to determine the dimensions of cultural landscapes, and secondly, to determine the dimensions of mining development in World Heritage cultural landscapes. The study used two case studies as an effective comparative research strategy in the investigation of the conflicting issues of mining development against the conservation of the attributes of the two cultural landscapes. A case study research strategy was combined with other research methodologies. These included interviews, focus-group-discussions, observations, field site surveys, qualitative content analysis, and thematic analysis.
The study has revealed that stakeholder participation and inclusion is a key element in the integration of mining development in cultural landscape planning. This research has contributed to the methodological gap in cultural landscape management planning by developing and applying an integrated strategic management planning methodological framework. The application of this framework has shown that the governance in place for Mulanje Mountain cultural landscape conformed to the requirements of a long-term and holistic planning process and the participation and empowerment of multiple stakeholders in that process.
The European Parliament and Council has defined a mandatory specific emission target of 95 g CO2/km by 2020 for passenger cars. Vehicle weight is a significant factor contributing to fuel consumption. Reducing the weight of the vehicle can be one promising option for decreasing CO2 emissions, which becomes a top priority for the automotive industry. In this research, two approaches were used to address the need. One involved developing structural parts using fibre reinforced plastics (FRP), and the other involved designing and developing FRP–metal hybrid laminates, which were constructed by reinforcing FRP locally to the metal surface. Existing joining techniques such as riveting, bolting, adhesive joining, ultrasonic welding, and flow drill joining techniques require additional processing steps to perform the joining, which could considerably increase processing time, cost, and energy expenditure. The present work describes a method to join FRP and metals using the adhesion strength of the investigated polymers. The developed FRP–metal hybrid laminates combine the advantages of metal and FRP together. Steel hot-stamping is known to yield very high strength. Fibre reinforced plastic–metal hybrid laminates were developed using hot stamped steels to transfer their superior mechanical properties to the final structure. To utilize the complete lightweight potential of thermoset and thermoplastic polymers, FRPs and FRP–metal hybrid laminates were developed using both the polymers. Along with this increased demand for FRP structures, there is growing interest in a repair technique in the automotive industry. The second objective of this thesis consists of designing and developing a new repair technique, which regains the strength and stiffness properties of the damaged part. The existing scarf repair technique is not suitable for thin laminates, which have limited access to the damaged area. Perforation damages were introduced into the FRP structures using a low-velocity impact load. A modified injection repair technique is used to repair these damaged FRP structures. Non-destructive techniques were utilized to understand the damage and the effectiveness of the repair.
Titanium and its alloys have been widely used as implant biomaterials due to their suitable combination of mechanical properties and biological compatibilities. At present, about 70-80% of implants are made of metallic biomaterials. Compared with magnesium alloys, stainless steel and cobalt alloys, titanium alloys have a higher specific strength, high corrosion resistance, and excellent biocompatibility. With research, Ti-Nb biomedical titanium alloys have been constantly developed. In the Ti-Nb alloy, the amount of Nb is usually from 16% to 42% (wt.%) which is about 10% to 30% (at.%). As reported, Mn as a trace element to the human body has the potential to be used in bio-materials. Therefore, this study aims at the partial replacement of Nb by Mn to reduce the costs, without deteriorating the mechanical properties. Moreover, it must be ensured good biocompatibility and corrosion resistance. This is the first investigated on Ti-Mn-Nb ternary alloys.
In this work, According to β single-phase field, Ti-xMn-yNb (x=4, 10, 16; y=2, 8, 14, at.%) alloys (arc-melted) have been fabricated. The Ti-Mn-Nb alloys are investigated by optical microscopy (OM), X-ray diffraction (XRD), hardness test, transmission electron microscopy (TEM) and mechanical testing. By screening study on alloy, Ti-10Mn-14Nb (at.%) (Ti-10Mn-23.7Nb (wt.%)) is the optimal alloy with tensile strength (760 MPa) and elongation (10.5%). After that, the Metal Injection Moulding (MIM) is used to prepare Ti-Mn-Nb alloys. The MIM method can greatly reduce the processing cost. MIM Ti-xMn-yNb (x=3, 4, 6; y=1, 2, 4, at.%), Ti-4Mn-14Nb and Ti-10Mn-14Nb alloys are fabricated. Among them, a very good combination of mechanical properties is achieved for MIM processed Ti-4Mn-2Nb (at.%) (Ti-4.5Mn-3.8Nb (wt.%)), namely a YS of 642 MPa, UTS of 725 MPa and high ductility of 16% elongation to fracture. With further investigations, when the yttrium content is 0.1% (at.%), the tensile strength of Ti-4Mn-2Nb-0.1Y (at.%) (Ti-4.5Mn-3.8Nb-0.18Y (wt.%)) is increased to 785 MPa while elongation of 12.9%. These mechanical properties already exceed Ti-6Al-4V (ASTM F2885 Grade 5 undensified).
In the in vitro evaluation, in comparison with MIM pure titanium, human osteoblasts MG63 adhered as well and proliferated on the surface of MIM Ti-Mn-Nb specimens. In the supernatant after cell culture, the Ti-Mn-Nb alloy shows similar osmolality and pH value results as MIM pure titanium. By LDH assay and DNA isolation, the MIM Ti-Mn-Nb alloys are not found to be toxic to MG63 cells.
In the study of corrosion resistance in Hanks’ balanced salt solution (HBSS) at 37 °C, the corrosion current densities as well as the impedance of MIM Ti-Mn-Nb alloys are all better than those of MIM pure titanium and even better than those of MIM Ti-6Al-4V alloy.
In this thesis we consider bilevel optimization problems in infinite-dimensional spaces. In particular, we are interested in providing first-order necessary optimality conditions. We consider bilevel optimization problems both in abstract Banach spaces and in some special situations. This includes the optimal control of the obstacle problem, which is a typical bilevel optimization problem in Sobolev spaces, as well as a class of inverse optimal control problems. We obtain optimality conditions for these more specific optimization problems by applying our results from the abstract setting.
Our main approach for deriving optimality conditions in the abstract setting utilizes the relaxation of a reformulation of the bilevel optimization problem via the optimal value function. We also introduce the so-called normal-cone-preserving operators and show how this concept can be applied.
We also consider other topics that arise in this context. For instance, we investigate the so-called limiting normal cone to a complementarity set in Sobolev spaces. This complementarity set plays a central role in the context of the optimal control of the obstacle problem. The limiting normal cone is a concept which appears in the area of variational analysis and generalizes the usual normal cone from convex analysis. We also investigate in which spaces Legendre forms and Legendre-* forms can exist. We show that if a Legendre-* form exists in a reflexive Banach space or a space with a separable predual space, then this space is already isomorphic to a Hilbert space. We also consider a discretization of a bilevel optimization problem in Lebesgue spaces. We present both theoretical error estimates and numerical experiments.
The new results in this thesis are illustrated by examples and counterexamples. In order to present the topics in a self-contained way, we review some known concepts and their basic properties. A particular focus for this is on the definitions and properties from the area of capacity theory.
The rebuilding of war-damaged historic cities has a significant impact on the way the affected societies can heal and recover in the post-conflict situation. If carried out without taking into consideration the inseparable relationship between the built structures and the formation of people’s identity, the reconstruction processes could cause more damage than the one endured due to the conflict. In this context, the rebuilding of cities and their historic centres in particular play a significant role in restoring the collective memory of the shared setting.
This dissertation researches the disturbing effects and trauma resulting from the deliberate destruction of heritage assets during armed conflicts, concerning both inhabitants and ancient urban structures. It discusses the discourse on the issue of post-conflict reconstruction that includes the arguments and recommendations made by several international experts and organizations which stipulates with both theoretical and practical outcome. The work of many theorists, authors, architects, philosophers, and professionals working in the field of heritage management, is examined thoroughly to provide a deep understanding of the issues discussed throughout this research.
The most recent illustration within this context is the war in Syria, which has caused excessive damage to the country’s cultural heritage. Noting that the military clashes have come to an end in several areas within the country and the physical damage has stopped, reconstruction projects have begun to materialize, and the urgent need for an overall consistent framework for rebuilding Syria is more crucial than ever.
Syria’s cultural heritage is facing a high threat of a second destruction, which will most likely follow if the involved governmental representatives, stakeholders, society or ‘societies’ did not realize the fundamental necessity for a value-based reconstruction approach which guarantees that the assessment of values is carried out and achieved in a balanced manner. Otherwise, mistakes will occur, and consequently, the collective memory and identity of the Syrians might never be recovered.
The rebuilding of post-war Syria is complex and challenging; it embraces more than a physical transformation of urban structures, and poses new threats to achieve psychological healing and recovering. The urban integrity of the Syrian cities is threatened, especially in the old city of Aleppo where the damage goes beyond the physical fabric and extends to endanger the city’s historical identity. Therefore, the main focus of the work is to develop a strategic framework which goes hand in hand with the traditional rebuilding approaches, and merges several practical and theoretical contexts deduced from previous case studies. The essence of the research revolves around understanding the significance of the city’s heritage and historic fabric, which must be considered a priority when deciding for the reconstruction procedures.
The overall research goal of this doctoral thesis is to better understand the determinants of sustainable purchase behaviour. By approaching several context-specific subgoals in a series of four quantitative empirical studies, major research gaps in the field of sustainable consumption are addressed. The first article examines the market potential for social banking in Germany. By means of an experimental survey using adaptive conjoint analysis, a sample of 2896 German social banking customers and a population-representative sample of 641 German conventional banking customers are compiled. Logistic regression modelling reveals that social banking customers differ significantly from their conventional counterparts regarding several consumer characteristics. The results further indicate a large untapped market potential ranging between 10 and 26% of the German population in 2011. The second article investigates the phenomenon of the attitude-behaviour gap in the context of sustainable clothing. Based on survey data of 1085 female German consumers, a structural equation model is estimated to assess how large the possible gap between a positive attitude towards sustainable clothing and the corresponding purchase behaviour is. Apart from a considerable attitude-behaviour gap, the article indicates that a positive attitude, self-transcendence values, as well as an affinity to online and catalogue shopping, significantly enhance sustainable clothing purchases. Self-enhancement values and, remarkably, a preference for durability constitute purchase barriers. The third article studies the influence of product lifetime labelling by the example of electrical appliances. Using choice-based conjoint analysis, experimental survey data is collected from a population-representative sample of 499 German consumers. Hierarchical Bayes utility modelling suggests a decreasing positive effect of the label on purchase decisions and a deterioration of the purchase influence of existing brands. Structural equation modelling indicates, for instance, that the preference for a long product lifetime is fostered by a respective positive attitude and subjective norm. However, the attitude only exerts a significant influence if it is driven by personal rather than environmental gains. The fourth article sheds light on the effects of favourable and unfavourable environmental product information. The analysis draws on data gained from a survey-based experiment conducted among a population-representative sample of 524 German consumers. Using a two-level structural equation model, the results document that the negative effect caused by unfavourable product carbon footprint information on consumers’ willingness to pay is significantly stronger than the positive effect caused by respective favourable information. Furthermore, consumers tend to not substantially differentiate between different high-range degrees of positive or negative environmental information.
The tiny logic elements in modern integrated circuits increase the rate of transient failures significantly. Therefore, redundancy on various levels is necessary to retain reliability. However, for mixed-criticality scenarios, the typical processor designs offer either too little fault-tolerance or too much redundancy for one part of the applications. Amongst others, we specifically address redundant processor internal functional units (FU) to cope with transient errors and support wear leveling. A real-time operating system (RTOS) was extended to control our prototypical hardware platform and, since it can be configured deterministically within few clock cycles, we are able to reconfigure the FUs dynamically, at process switching time, according to the specified critically of the running processes. Our mechanisms were integrated into the Plasma processor and the Plasma-RTOS. With few changes to the original software code, it was, for example, possible to quickly change from fault-detecting to fault-correcting modes of the processor on demand.
The material authenticity of cultural heritage has been questioned by societies in which the modern paradigm of conservation has not developed from within the native culture. This paper examines the philosophical and practical traditions in Iran regarding the materiality and authenticity of past structures. By reviewing the emergence of the Western conservation paradigm in Iran, this paper highlights two key factors: the rapidness of this paradigm shift and the remarkable contradiction between the new and old paradigms. By borrowing the Deleuzo-Guattarian concept of a ‘body without organs’ (BwO), this paper problematises the rapidness and radicality of the paradigm shift in Iran. It suggests exploring the under-investigated possibilities between the pre-modern and modern paradigms to address the gap between native circumstances and Western standards.
System reconfiguration of hardware resources has been done in multiple system domains. Such systems are usually found in the context of FPGAs, where reconfiguration is done usually over its primitives (e.g., LUTs, Flip-Flops). Or even in the context of MPSoC designs, where core management (e.g., lock-step operation in multi-core designs) is the most used approach. However, recent works have shown that configuration at Functional Units (FUs) granularity might come with benefits. For example, it can increase the configuration space due to its finer granularity, and, as a consequence, the options to deal with problems (e.g., due to aging) in the units itself. Within this context, this paper presents a system capable to configure its FUs (e.g., ALUs, multipliers, dividers) into different operation modes. The system uses an Operating System to control HW reconfiguration during process switching time and takes into account the health state of its units in a mixed-criticality applications scenario. Results show that, within this scenario, the system is able to reconfigure itself accomplishing health state modifications of its HW elements.
The German Armed Forces provide an operation contingent to support the North Atlantic Treaty Organization (NATO) Response Force (NRF). For this purpose, a „warehouse” containing accommodations, food supplies, medical supplies, and spare parts for the systems has to be available. Such a warehouse is restricted in weight, in order to be quickly movable in an upcoming deployment situation. It should be able to supply the NRF troops for a certain amount of time (e.g., one month) without re-supply from the outside. To ensure optimal use of such a restricted warehouse, we developed the computer program „The OPtimization of a Spare Parts Inventory” (TOPSPIN) to find an optimal mix of spare parts to restore a set of systems to functionality. Each system is composed of several parts, and it can only be used again in the mission if all broken parts are replaced. The failure rate of the individual parts follows a given random distribution, and during deployment it is expected to be higher than in the homeland. Due to the stochastic nature of the problem, we generate scenarios that simulate the actual failure of the parts. The backbone of TOPSPIN is a mixed-integer linear program that determines an optimal, scenario-robust mix of spare parts and is solved using standard state-of-the-art numerical solvers. Using input data provided by the Logistikzentrum, we analyze how many scenarios need to be generated in order to determine reliable solutions. Moreover, we analyze the composition of the warehouse over a variety of different weight restrictions, and we calculate the number of repairable systems as a function of this bound.
The subject of this thesis is the development and test of silicon strip detectors for the high luminosity upgrade of the tracking detector of the ATLAS experiment at the Large Hadron Collider. Special emphasis is devoted to the understanding of the impact of mechanical stress on the electrical properties and the particle detection performance of detector modules.
First simulations were done to estimate the maximum expected stress on a sensor when operated at -30 °C within the future silicon strip tracking detector ITk, at ATLAS. The maximum stress in a worst case scenario is expected to be 27 MPa. Tensile strength tests were done to estimate the maximum stress which can be applied to a silicon strip sensor. Silicon shards, with a thickness and dopand concentration corresponding to the ITk sensor specifications break at >23 MPa, wafers at >700 MPa and sensors at ~ 400 MPa. The huge variations lead to the assumption, that the tensile stregth, which is highly dependent on the quality of the crystal lattice, is due to different cutting technology. Wafers, irradiated with a fluence equivalent of a lifetime dose of an ITk sensor, show no stress dependency of the youngs modulus. The tensile strength of irradiated wafers is decreased by ~ 6,6 %. No damage on silicon sensors from mechanical stress is expected for sensor modules installed it the ITk.
The electrical properties of silicon strip sensors were studied for applied mechanical stress on ATLAS07 sensors up to 60 MPa. The specifications of the sensors are similar to the specification of strip sensors in the future silicon strip tracker barrel region of the ATLAS detector. The leakage current changes at 50 MPa by -1.7 %, the bias resistance by +0.8 % and the interstrip resistance by -25 %. The depletion voltage and the implant resistance are not affected by mechanical stress. Except for the interstrip resistance the results can be explained by piezoresistive effects.
Silicon strip modules were build and studied in particle test beams. These modules consists of an ATLAS07 or an ATLAS12 sensor and an analogue readout to study the influence of stress on the module performance. The sensor module noise is independent from the applied stress. An effect of stress on the signal strength was seen. The ATLAS07 sensor module signal strength was decreased and the ATLAS12 sensor module signal strength was increased with a slope of ~0,6 MPa^-1. The average cluster size of the ATLAS07 sensor module was increased by 0,25 % MPa^-1 and the average cluster size of the ATLAS12 sensor module was decreased by 0,06 % MPa^-1 with applied stress.
The investigation of novel structure-to-property relations of many transition metal trihalides MX₃ by downscaling to promising monolayer is still pending. However, the production of two-dimensional MX₃ sheets that are both high crystalline and thin is an experimental challenge. This thesis is focused on the rational synthesis planning and the derived targeted preparation of thin MX₃ nanosheets (≤ 100 nm) on suitable substrates by chemical vapor transport (CVT) as well as their characterization by complementary analytical methods. CVT of nanosheets directly on substrates benefits of low timescales, less material consumption and only few structural distortions. For the determination of optimal growth conditions, the CVT processes of investigated compounds were initially simulated by using the Calphad method (program package TRAGMIN). Thus, the occurring transport efficient gas species and temperature dependent, dominating vapor transport equilibria were calculated to optimize the growth process in a direct and straightforward way. Based on prior simulation results single crystalline sheets of MCl₃ (M = Ru, Mo, Ti, Cr) and CrX₃ (X = I, Br, Cl) were successfully prepared at temperatures between 573 – 1023 K on YSZ (yttrium stabilized zirconia) or sapphire substrates. The adjustable CVT parameters (transport duration, temperatures or weighed starting material) were optimized with respect to the targeted synthesis of either bulk or nanosheets at substrates. Microsheets with thicknesses of less than 4 μm (α-TiCl₃) and about 20 nm thin nanosheets (α-RuCl₃, CrCl₃ and CrI₃) down to ultrathin flakes (≈ 3 nm, α-MoCl₃ and CrBr₃) were obtained by CVT. As a highlight, monolayers of α-RuCl₃ and CrCl₃ were isolated successfully by means of a subsequent delamination. The MX₃ sheets morphology and dimension was described by optical and electron microscopy, highlighting their two-dimensional nature. By several X-ray spectroscopy and diffraction techniques the desired composition (M:X = 1:3), high crystallinity and phase-purity of thick and thin MX₃ platelets was confirmed subsequently. With respect to MX₃ nanosheets a slight increase (α-RuCl₃, α-MoCl₃ and CrBr₃) or decrease (CrCl₃) in phonon energies was observed in comparison to their bulk counterparts. The magnetic properties of CrCl₃ micro- and nanosheets were determined to be solely ferromagnetic and thus different than those of the bulk samples. Finally, the structure-to-property relations were investigated at a first example. The catalytic properties of α-TiCl₃ microsheets were investigated by gas-phase polymerization of ethylene. By downscaling the catalysts thickness by CVT, we obtained an activity improvement of 24 % in comparison to bulk α-TiCl₃.
Tattoo taboo : a reader
(2020)
In different parts of the world, tattoos historically have been expression of the socio-cultural identity of individuals or communities: Tattoos are firmly integrated into social practices as elements of initiation or marriage, in other parts of the world, however, tattoos carry negative associations being linked to immorality, and crime.
To research the practice of and places associated with tattooing a research-based study project was designed to address the practice of tattooing from the point of view of its cultural heritage values, both intangible and tangible. In the winter semester 2018/2019 this study project was offered jointly by the Chair of Architectural Conservation and the Department of Heritage Management at the Brandenburg University of Technology (BTU) Cottbus-Senftenberg. Twelve international students from the study programmes World Heritage Studies and Architecture participated in this study project, which included a field trip to London and Oxford and several interviews and interactions with researchers and academics from the fields of tattoo history, anthropology, medical sciences and museography.
A collection of students’ essays on this topic is presented in this reader with a particular focus on the tangible and intangible aspects of tattooing, and the spatial history of tattooing based on two distinct areas in London as a case study.
The papers are divided into three distinctive themes that are linked to the practice of tattooing. Section one is dedicated to tattoos as a form of heritage, the one to tattooing as a form of art, and the last one to mapping as a methodological tool to visualise, assess and present relationships between heritage, tattooing practice and its connection to the social fabric in London at the turn of the penultimate century.
This thesis deals with a novel approach for analyzing and computing interior transmission eigenvalues of (piecewise) homogeneous media in two dimensions. It is based on approximating boundary data of respective eigenfunctions by the method of fundamental solutions. However, since a straightforward implementation would solely exploit ill-conditioned matrices and thus evoke spurious results, a stabilization scheme is incorporated. The combined method is then studied with a distinction between isotropic and anisotropic materials, and complemented by novel approximation theory each. Numerical validations complete the investigations for different wave type scenarios
The modern world is currently facing the energy revolution due to the decarbonisation challenges, promoted by the United Nations Framework Convention on Climate Change (UNFCCC). The well-established fossil fuel energy sources are being pushed from their leading market positions by renewable energy. European governments are some of the first to take decisive action towards decarbonisation and have already started reforming their economic sectors. New questions arising from such changes are influencing the role of Russia in supplying energy to the European market. The development of a market for renewable gas, especially renewable hydrogen in Europe, could potentially, in a long-term scenario up to 2050, be an option for Russia to help maintain demand and remain in the role as a main exporter.
The focus of this master thesis is put on the assessment of the current state of readiness of Russian and European energy systems for integration of Power-to-Gas (PtG) systems and for development of a carbon-free hydrogen market. German internal green hydrogen production capacity cannot meet the approximate demand in 2030 and 2050. However, the presence of the unutilised power capacity from Russian nuclear and hydro power plants opens a new opportunity to generate economically attractive hydrogen in large volumes via electrolysis with low electricity costs and zero carbon dioxide footprint.
In this thesis different supply chains for hydrogen export (Russia-Germany) are constructed and, as a result, the levelised costs of hydrogen (LCOH) are calculated and analysed. Hydrogen produced in Russia and transported to Germany via maritime shipment shows that it can already be competitive to the domestically produced green hydrogen in Germany. The main compartment of the LCOH is the electricity expenditure, which the current Russian industrial tariffs can reach up to 90% of the total costs. Further reductions of the electricity price for PtG systems are recommended in order to achieve lower results for the LCOH.
The outcome of this master thesis provides an overview on the current readiness of Russian and German hydrogen infrastructure and further recommendations on how it should be adapted. Finally a 2050 roadmap for the implementation of a hydrogen market in Russia and Germany is developed.