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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Design and Construction Modifications of Switched Reluctance Machines / Entwurf und konstruktive Modifikationen von Geschalteten Reluktanzmaschinen

Wichert, Torsten 25 February 2009 (has links) (PDF)
Although the design principles of the Switched Reluctance Machines (SRMs) are available in different fragments in numerous bibliography positions, there no exists the complex design procedure of whole drive system taking into account the SR Machine, control system and supply device as well. The hybrid design method for SRM drives with application of new analytical calculation methods, finite element method and simulation models is proposed in this thesis. The calculation/design system is characterised by important effectivity and reliability. The new possibilities in analytical determination of saturation effects and core losses under various modes of control, including sensorless method, are also taken into account. The correctness of the proposed design algorithms are verified by laboratory tests made on three motor prototypes manufactured in industry for concrete application. This dissertation provides the elements indispensable for more accurate and complex analysis and design of drives with switch reluctance motors. The elements of electrical motor and control system design as well as the considerations on the choice of supply device and controller subsystems are jointed in the thesis for final receiving of the design tool for considered industrial drive system.
32

Metabolite aus marinen und terrestrischen Bakterien und Pilzen sowie Untersuchungen von Invertebraten der Tiefsee / Metabolites of marine and terrestrial Bacterias and Fungis as well as Investigations of Invertebrates from the deep sea

Schulze, Andrea 08 May 2003 (has links)
No description available.
33

50 Jahre Nukleare Analytik in Rossendorf – interdisziplinäre Forschung und Dienstleistungen / 50 Years Radioanalytical Chemistry in Rossendorf – Interdisciplinary Research and Service

Niese, Siegfried 01 October 2013 (has links) (PDF)
Die Nukleare Analytik begann in Rossendorf im Jahr 1957 mit der Anwendung der Indikatormethode für Verteilungsuntersuchungen im Zusammenhang mit der Verarbeitung bestrahlter Kernbrennstoffe. Nach Inbetriebnahme des Forschungsreaktors stand die Entwicklung und Anwendung der Aktivierungsanalyse zur Untersuchung von Halbleitermaterialen sowie geologischer und medizinischer Proben im Mittelpunkt. Zur Verbesserung der Nachweisgrenze von Radionukliden wurden Koinzidenzverfahren entwickelt und eine unterirdische Messkammer eingerichtet. Nach Stilllegung des Forschungsreaktors wurde die Radioaktivität in der Umgebung des ehemaligen Uranbergbaues, in Materialien aus dem Rückbau von Reaktoren und anderen Kernanlagen und anderen natürlichen und technischen Proben bestimmt. / In 1957 the work in radioanalytical chemistry has been started in Rossendorf with the application of the tracer method for investigation of the distribution of nuclides in reprocessing of nuclear fuels. After put into operation of the research reactor the development and application of activation analysis became the main topic. For improvement of the detection limits of radionuclides coincidence methods has been developed and an underground counting room was build. After shut down of the research reactor the radioactivity in the environment of the former uranium mining, and in materials from the decommissioning of reactors and other nuclear equipments and further natural and industrial samples.
34

Kants transzendentale Deduktion der Kategorien als Begründung der Metaphysik der Natur /

Bae, Jeong-Ho. January 2007 (has links)
Zugl.: Wuppertal, Universiẗat, Diss., 2007.
35

50 Jahre Nukleare Analytik in Rossendorf – interdisziplinäre Forschung und Dienstleistungen

Niese, Siegfried 01 October 2013 (has links)
Die Nukleare Analytik begann in Rossendorf im Jahr 1957 mit der Anwendung der Indikatormethode für Verteilungsuntersuchungen im Zusammenhang mit der Verarbeitung bestrahlter Kernbrennstoffe. Nach Inbetriebnahme des Forschungsreaktors stand die Entwicklung und Anwendung der Aktivierungsanalyse zur Untersuchung von Halbleitermaterialen sowie geologischer und medizinischer Proben im Mittelpunkt. Zur Verbesserung der Nachweisgrenze von Radionukliden wurden Koinzidenzverfahren entwickelt und eine unterirdische Messkammer eingerichtet. Nach Stilllegung des Forschungsreaktors wurde die Radioaktivität in der Umgebung des ehemaligen Uranbergbaues, in Materialien aus dem Rückbau von Reaktoren und anderen Kernanlagen und anderen natürlichen und technischen Proben bestimmt. / In 1957 the work in radioanalytical chemistry has been started in Rossendorf with the application of the tracer method for investigation of the distribution of nuclides in reprocessing of nuclear fuels. After put into operation of the research reactor the development and application of activation analysis became the main topic. For improvement of the detection limits of radionuclides coincidence methods has been developed and an underground counting room was build. After shut down of the research reactor the radioactivity in the environment of the former uranium mining, and in materials from the decommissioning of reactors and other nuclear equipments and further natural and industrial samples.
36

Biofunctionalization of Polymer Brush Surfaces

Psarra, Evmorfia 10 June 2015 (has links)
Surface engineering of tailored materials with adjustable characteristics in relation to biological environment, is one of the main prerequisites for biotechnological applications. In recent years, advanced surface coatings in the nanometer range have drawn big attention. A special category of this group are stimuli responsive polymers tethered by one functional end to the surface. When the surface grafting density is big enough, the polymer chains are forced to stretch away from the interface due to excluded volume effects, creating a so called polymer brush. Nano-scaled polymer brushes are advantageous due to their nanostructure, which can be comparable to biological species, and their collaborative response to external stimuli. Moreover, the material design parameters such as chemistry, surface topography, charge, and surface wettability can be adjusted by using the appropriate polymer, or a combination of polymers with respect to the desired material performance. In case of binary polymer brushes, the materials' properties are switched between the properties of two constituent polymers. Besides, upon switching of external stimuli, biomodified binary polymer brushes can hide or expose biofunctionalities, on demand. Hence, they are classified as smart biomaterials' surface coatings.
37

Temperature Dependent Size Exclusion Chromatography for Investigating Thermoreversibly Bonding Polymer Systems

Brandt, Josef 11 July 2016 (has links)
Polymers capable of thermally controlled reversible bonding reactions are promising candidates for stimuli responsive materials, as required for self-healing or drug delivery materials. In order to investigate how the dynamic reactions can be controlled, effective analytical tools are demanded that are capable of analyzing not only the polymers but can also monitor the respective bonding reactions. Herein, we employ size exclusion chromatography in a newly developed temperature dependent mode (TD SEC) for the in situ characterization of polymers that undergo retro Diels-Alder (rDA) reaction at temperatures higher than 60 °C. Monitoring the evolution of the molar mass distribution of the polymers during the rDA reaction and evaluating the data quantitatively gives detailed information about the extent of the reaction and allows elucidating structural parameters that can be used for controlling the polymers debonding behavior. In contrast to spectroscopic techniques, TD SEC analyzes only the size of the polymers, hence the polymers do not need to fulfill any particular requirements (e.g. presence of detectable functional groups) but only need to be soluble in the TD SEC, which makes the method universally applicable. Side effects that might bias the results are minimized by using a high temperature chromatograph that allows performing the analysis in a broad temperature range (60 – 200 °C) and in different solvents. Thus, the analysis can be performed under the exact conditions that are required for the bonding reactions and an in situ image is provided.
38

Design and Construction Modifications of Switched Reluctance Machines

Wichert, Torsten 26 July 2008 (has links)
Although the design principles of the Switched Reluctance Machines (SRMs) are available in different fragments in numerous bibliography positions, there no exists the complex design procedure of whole drive system taking into account the SR Machine, control system and supply device as well. The hybrid design method for SRM drives with application of new analytical calculation methods, finite element method and simulation models is proposed in this thesis. The calculation/design system is characterised by important effectivity and reliability. The new possibilities in analytical determination of saturation effects and core losses under various modes of control, including sensorless method, are also taken into account. The correctness of the proposed design algorithms are verified by laboratory tests made on three motor prototypes manufactured in industry for concrete application. This dissertation provides the elements indispensable for more accurate and complex analysis and design of drives with switch reluctance motors. The elements of electrical motor and control system design as well as the considerations on the choice of supply device and controller subsystems are jointed in the thesis for final receiving of the design tool for considered industrial drive system.
39

Data Science and Analytics in Industrial Maintenance: Selection, Evaluation, and Application of Data-Driven Methods

Zschech, Patrick 02 October 2020 (has links)
Data-driven maintenance bears the potential to realize various benefits based on multifaceted data assets generated in increasingly digitized industrial environments. By taking advantage of modern methods and technologies from the field of data science and analytics (DSA), it is possible, for example, to gain a better understanding of complex technical processes and to anticipate impending machine faults and failures at an early stage. However, successful implementation of DSA projects requires multidisciplinary expertise, which can rarely be covered by individual employees or single units within an organization. This expertise covers, for example, a solid understanding of the domain, analytical method and modeling skills, experience in dealing with different source systems and data structures, and the ability to transfer suitable solution approaches into information systems. Against this background, various approaches have emerged in recent years to make the implementation of DSA projects more accessible to broader user groups. These include structured procedure models, systematization and modeling frameworks, domain-specific benchmark studies to illustrate best practices, standardized DSA software solutions, and intelligent assistance systems. The present thesis ties in with previous efforts and provides further contributions for their continuation. More specifically, it aims to create supportive artifacts for the selection, evaluation, and application of data-driven methods in the field of industrial maintenance. For this purpose, the thesis covers four artifacts, which were developed in several publications. These artifacts include (i) a comprehensive systematization framework for the description of central properties of recurring data analysis problems in the field of industrial maintenance, (ii) a text-based assistance system that offers advice regarding the most suitable class of analysis methods based on natural language and domain-specific problem descriptions, (iii) a taxonomic evaluation framework for the systematic assessment of data-driven methods under varying conditions, and (iv) a novel solution approach for the development of prognostic decision models in cases of missing label information. Individual research objectives guide the construction of the artifacts as part of a systematic research design. The findings are presented in a structured manner by summarizing the results of the corresponding publications. Moreover, the connections between the developed artifacts as well as related work are discussed. Subsequently, a critical reflection is offered concerning the generalization and transferability of the achieved results. Thus, the thesis not only provides a contribution based on the proposed artifacts; it also paves the way for future opportunities, for which a detailed research agenda is outlined.:List of Figures List of Tables List of Abbreviations 1 Introduction 1.1 Motivation 1.2 Conceptual Background 1.3 Related Work 1.4 Research Design 1.5 Structure of the Thesis 2 Systematization of the Field 2.1 The Current State of Research 2.2 Systematization Framework 2.3 Exemplary Framework Application 3 Intelligent Assistance System for Automated Method Selection 3.1 Elicitation of Requirements 3.2 Design Principles and Design Features 3.3 Prototypical Instantiation and Evaluation 4 Taxonomic Framework for Method Evaluation 4.1 Survey of Prognostic Solutions 4.2 Taxonomic Evaluation Framework 4.3 Exemplary Framework Application 5 Method Application Under Industrial Conditions 5.1 Conceptualization of a Solution Approach 5.2 Prototypical Implementation and Evaluation 6 Discussion of the Results 6.1 Connections Between Developed Artifacts and Related Work 6.2 Generalization and Transferability of the Results 7 Concluding Remarks Bibliography Appendix I: Implementation Details Appendix II: List of Publications A Publication P1: Focus Area Systematization B Publication P2: Focus Area Method Selection C Publication P3: Focus Area Method Selection D Publication P4: Focus Area Method Evaluation E Publication P5: Focus Area Method Application / Datengetriebene Instandhaltung birgt das Potential, aus den in Industrieumgebungen vielfältig anfallenden Datensammlungen unterschiedliche Nutzeneffekte zu erzielen. Unter Verwendung von modernen Methoden und Technologien aus dem Bereich Data Science und Analytics (DSA) ist es beispielsweise möglich, das Verhalten komplexer technischer Prozesse besser nachzuvollziehen oder bevorstehende Maschinenausfälle und Fehler frühzeitig zu erkennen. Eine erfolgreiche Umsetzung von DSA-Projekten erfordert jedoch multidisziplinäres Expertenwissen, welches sich nur selten von einzelnen Personen bzw. Einheiten innerhalb einer Organisation abdecken lässt. Dies umfasst beispielsweise ein fundiertes Domänenverständnis, Kenntnisse über zahlreiche Analysemethoden, Erfahrungen im Umgang mit verschiedenen Quellsystemen und Datenstrukturen sowie die Fähigkeit, geeignete Lösungsansätze in Informationssysteme zu überführen. Vor diesem Hintergrund haben sich in den letzten Jahren verschiedene Ansätze herausgebildet, um die Durchführung von DSA-Projekten für breitere Anwendergruppen zugänglich zu machen. Dazu gehören strukturierte Vorgehensmodelle, Systematisierungs- und Modellierungsframeworks, domänenspezifische Benchmark-Studien zur Veranschaulichung von Best Practices, Standardlösungen für DSA-Software und intelligente Assistenzsysteme. An diese Arbeiten knüpft die vorliegende Dissertation an und liefert weitere Artefakte, um insbesondere die Selektion, Evaluation und Anwendung datengetriebener Methoden im Bereich der industriellen Instandhaltung zu unterstützen. Insgesamt erstreckt sich die Abhandlung auf vier Artefakte, die in einzelnen Publikationen erarbeitet wurden. Dies umfasst (i) ein umfangreiches Systematisierungsframework zur Beschreibung zentraler Ausprägungen wiederkehrender Datenanalyseprobleme im Bereich der industriellen Instandhaltung, (ii) ein textbasiertes Assistenzsystem, welches ausgehend von natürlichsprachlichen und domänenspezifischen Problembeschreibungen eine geeignete Klasse von Analysemethoden vorschlägt, (iii) ein taxonomisches Evaluationsframework zur systematischen Bewertung von datengetriebenen Methoden unter verschiedenen Rahmenbedingungen sowie (iv) einen neuartigen Lösungsansatz zur Entwicklung von prognostischen Entscheidungsmodellen im Fall von eingeschränkter Informationslage. Die Konstruktion der Artefakte wird durch einzelne Forschungsziele im Rahmen eines systematischen Forschungsdesigns angeleitet. Neben der Darstellung der einzelnen Forschungsbeiträge unter Bezugnahme auf die erzielten Ergebnisse der dazugehörigen Publikationen werden auch die Verbindungen zwischen den entwickelten Artefakten beleuchtet und Zusammenhänge zu angrenzenden Arbeiten hergestellt. Zudem erfolgt eine kritische Reflektion der Ergebnisse hinsichtlich ihrer Verallgemeinerung und Übertragung auf andere Rahmenbedingungen. Dadurch liefert die vorliegende Abhandlung nicht nur einen Beitrag anhand der erzeugten Artefakte, sondern ebnet auch den Weg für fortführende Forschungsarbeiten, wofür eine detaillierte Forschungsagenda erarbeitet wird.:List of Figures List of Tables List of Abbreviations 1 Introduction 1.1 Motivation 1.2 Conceptual Background 1.3 Related Work 1.4 Research Design 1.5 Structure of the Thesis 2 Systematization of the Field 2.1 The Current State of Research 2.2 Systematization Framework 2.3 Exemplary Framework Application 3 Intelligent Assistance System for Automated Method Selection 3.1 Elicitation of Requirements 3.2 Design Principles and Design Features 3.3 Prototypical Instantiation and Evaluation 4 Taxonomic Framework for Method Evaluation 4.1 Survey of Prognostic Solutions 4.2 Taxonomic Evaluation Framework 4.3 Exemplary Framework Application 5 Method Application Under Industrial Conditions 5.1 Conceptualization of a Solution Approach 5.2 Prototypical Implementation and Evaluation 6 Discussion of the Results 6.1 Connections Between Developed Artifacts and Related Work 6.2 Generalization and Transferability of the Results 7 Concluding Remarks Bibliography Appendix I: Implementation Details Appendix II: List of Publications A Publication P1: Focus Area Systematization B Publication P2: Focus Area Method Selection C Publication P3: Focus Area Method Selection D Publication P4: Focus Area Method Evaluation E Publication P5: Focus Area Method Application
40

Towards Scalable Real-time Analytics:: An Architecture for Scale-out of OLxP Workloads

Goel, Anil K., Pound, Jeffrey, Auch, Nathan, Bumbulis, Peter, MacLean, Scott, Färber, Franz, Gropengiesser, Francis, Mathis, Christian, Bodner, Thomas, Lehner, Wolfgang 10 January 2023 (has links)
We present an overview of our work on the SAP HANA Scale-out Extension, a novel distributed database architecture designed to support large scale analytics over real-time data. This platform permits high performance OLAP with massive scale-out capabilities, while concurrently allowing OLTP workloads. This dual capability enables analytics over real-time changing data and allows fine grained user-specified service level agreements (SLAs) on data freshness. We advocate the decoupling of core database components such as query processing, concurrency control, and persistence, a design choice made possible by advances in high-throughput low-latency networks and storage devices. We provide full ACID guarantees and build on a logical timestamp mechanism to provide MVCC-based snapshot isolation, while not requiring synchronous updates of replicas. Instead, we use asynchronous update propagation guaranteeing consistency with timestamp validation. We provide a view into the design and development of a large scale data management platform for real-time analytics, driven by the needs of modern enterprise customers.

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