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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.
51

Fullerene im Strahlungsgleichgewicht - Untersuchungen in einem Quadrupolspeicher

Decker, Silvio 03 December 2009 (has links) (PDF)
Das wissenschaftliche Ziel der Arbeit ist die Untersuchung von optischen und chemischen Eigenschaften von kohlenstoffhaltigen Teilchen im besonderen Fullerene bei hohen Temperaturen. Die Arbeit behandelt im Detail den Aufbau und die Charakterisierung einer Messapparatur zur Untersuchung von Fulleren-Kationen. Nach einer kurzen Einführung zum Thema und einer Beschreibung des Aufbaus der Arbeit beginnt diese mit der Charakterisierung der Apparatur als Ganzes und ihrer Elemente. Dazu gehört die weiterentwickelte Sublimationsionenquelle, der Quadrupolspeicher und der Ionendetektor. Es werden eingehende Messungen zur Speicherung und zum Nachweis der absoluten Zahl von gespeicherten Ionen vorgestellt. Weiterhin wird das optische Nachweissystem bezüglich der Sammelleistung und des Empfindlichkeit eingehend untersucht. Nach der Einführung in die Apparatur wird die Verteilung der Ionen im Speicher näher beleuchtet und gezeigt, dass ein optischer Nachweis der Zahl gespeicherter Ionen möglich ist. Außerdem wird gezeigt, dass es gelingt die kinetische Temperatur der Ionen im Speicher, durch die geometrische Vermessung der Ionenverteilung zu bestimmen. Im weiteren wird auf die thermische Emission heißer C60+ näher eingegangen. Dazu wird ein klassisches dielektrisches Modell zur thermischen Emission vorgestellt. Es werden Messprinzipien zur Temperaturbestimmung der lasergeheizten Ionen erörtert und Messungen zur Temperatur des Ionenensembles präsentiert. Weiterhin werden Messungen zum C2-Verlust von C60+ als Funktion der Temperatur vorgestellt. Die experimentell ermittelte Aktivierungsenergie der C2-Verlustreaktion mit Ea = 2,3...5,4eV zeigt deutliche Abweichungen zu bekannten Literaturwerten. Die Ergebnisse dieser Messung werden mit einer nummerischen Simulation zur Energieverteilung im Ionenensemble diskutiert. Die Arbeit endet mit einer Zusammenfassung und einem Ausblick auf weitere experimentelle Möglichkeiten der Messmethode. Ersetzt durch neues Dokument, wegen URL auf Titelseite. / The scientific goal of this work is the study of optical and chemical properties of carbon containing particles especially fullerenes at high temperatures. This work covered the construction and characterization of the measuring apparatus for the investigation of fullerene cations. It follows a characterization of the apparatus and its elements after a short introduction and a description of the structure of this work. This involved the further developed sublimation ion source, the quadrupole trap and the ion detections system. Extensive measurements of the ion trapping and the proof of the absolute number of trapped ions are presented. Further on the optical detections system is characterized in depth regarding the collection efficiency and sensitivity. After the introduction in the apparatus the distribution of the ions inside the trap is closer examined. The possibility of the optical detections of the number of trapped ions is shown. Additionally it is pointed out that the kinetic temperature of the ions can be extracted by geometrical measurement of the ion distribution. Further on it is enlarged on the thermal emission of hot C60. For this a classical dielectric model for the thermal emission is presented. Measuring principals of the temperature determination of laser heated ions are discussed and temperature measurements of the ion ensemble are presented. Measurements of the C2-loss as function of the temperature are presented. The results of the extracted activation energy of Ea = 2.3...5.4eV for the C2-loss reaction of C60+ shows a discrepancy to literature results. The results of this measurements are discussed with help of an numerical simulation of the internal energy distribution of the ion ensemble. This work closes with a summery and an outlook of further experimental potentialities of the measuring method. Replaced by new document, because of URL on the title page.
52

From forest to fairway : hull analysis of 'La belle', a late seventeenth-century French ship

Carrell, Toni L. January 2003 (has links)
This thesis is a comprehensive analysis of the hull remains of La Belle, a ship wrecked off the coast of Texas in 1684 during the failed attempt by Robert Cavelier Sieur de La Salle to establish a colony at the mouth of the Mississippi River. The analysis of La Belle's hull focused on five research goals. The first was to reconstruct the conception and design of the hull. Because La Belle was built on France's Atlantic coast, it was expected that the ship would fit into Atlantic traditions of shipbuilding. Instead, it exhibits an ancient Mediterranean method known only from Renaissance manuscripts. Until La Belle's discovery no archaeological example associated with this method had been identified. Reconstruction of the lines also revealed the unexpected use of surmarks that reflect a transition from a largely empirical approach to the architecturally-based ship plan. The second goal was the documentation of a previously unstudied ship type, the barque longue, through an analysis and description of the hull's assembly and its comparison to contemporary shipbuilding practices. The third goal was an analysis of newly discovered registries, letters, and documents specific to La Belle that raised fundamental questions regarding the ship's genesis and typological identification. The fourth goal was species identification of the timbers to provide a more detailed picture of forest exploitation and to identify whether Old or New World timbers were used in the repairs noted in the hull. The fifth goal was to obtain information on the origin of the wood through dendrochronological analysis. That analysis raised unexpected questions regarding dating and the possibility of re-use of whole frame sets. Because there are no other investigated late 17th-century shipwreck sites from the Rochefort region with species and dendrochronology data, La Belle has provided a benchmark for these two analyses. These five research foci provide a unique picture of late 17th-century shipbuilding in French Atlantic shipyards and contribute to the study of hull design, ship typology, construction and assembly, wood species use and origin, dendrochronological dating, and timber reuse.
53

ONTOLOGY-BASED DATA FUSION WITHIN A NET-CENTRIC INFORMATION EXCHANGE FRAMEWORK

Lee, Hojun January 2009 (has links)
With the advent of Network-Centric Warfare (NCW) concepts, Command and Control (C2) Systems need efficient methods for communicating between heterogeneous systems. To extract or exchange various levels of information within the networks requires interoperability between human and machine as well as between machine and machine. This dissertation explores the Information Exchange Framework (IEF) concept of distributed data fusion sensor networks in Network-centric environments. It is used to synthesize integrative battlefield pictures by combining the Battle Management Language (BML) and System Entity Structure (SES) ontology framework for C2 systems. The SES is an ontology framework that can facilitate information exchange in a network environment. From the perspective of the SES framework, BML serves to express pragmatic frames, since it can specify the information desired by a consumer in an unambiguous way. This thesis formulates information exchange in the SES ontology via BML and defines novel pruning and transformation processes of the SES to extract and fuse data into higher level representations. This supports the interoperability between human users and other sensor systems. The efficacy of such data fusion and exchange is illustrated with several battlefield scenario examples.A second intercommunication issue between sensor systems is how to ensure efficient and effective message passing. This is studied by using Cursor-on-Target (CoT), an effort to standardize a battlefield data exchange format. CoT regulates only a few essential data types as standard and has a simple and efficient structure to hold a wide range of message formats used in dissimilar military enterprises. This thesis adopts the common message type into radar sensor networks to manage the target tracking problem in distributed sensor networks.To demonstrate the effectiveness of the proposed Information Exchange Framework for data fusion systems, we illustrate the approach in an air defense operation scenario using DEVS modeling and simulation. The examples depict basic air defense operation procedure. The demonstration shows that the information requested by a commander is delivered in the right way at the right time so that it can support agile decision making against threats.
54

How Effective is European Merger Control?

Duso, Tomaso, Gugler, Klaus, Yurtoglu, Burcin B. 10 1900 (has links) (PDF)
This paper applies an intuitive approach based on stock market data to a unique dataset of large concentrations during the period 1990-2002 to assess the effectiveness of European merger control. The basic idea is to relate announcement and decision abnormal returns. Under a set of four maintained assumptions, merger control might be interpreted to be effective if rents accruing due to the increased market power observed around the merger announcement are reversed by the antitrust decision, i.e. if there is a negative relation between announcement and decision abnormal returns. To clearly identify the events' competitive effects, we explicitly control for the market expectation about the outcome of the merger control procedure and run several robustness checks to assess the role of our maintained assumptions. We find that only outright prohibitions completely reverse the rents measured around a merger's announcement. On average, remedies seem to be only partially capable of reverting announcement abnormal returns. Yet they seem to be more effective when applied during the first rather than the second investigation phase and in subsamples where our assumptions are more likely to hold. Moreover, the European Commission appears to learn over time. (authors' abstract)
55

Charakterisierung der Aktin-ADP-Ribosyltransferase SpvB aus Salmonella enterica

Figura, Guido von, January 2005 (has links)
Freiburg i. Br., Univ., Diss., 2007.
56

Theory and observations of the magnetic field in the solar corona

Carcedo, Laura January 2005 (has links)
Although the solar corona is one of the most studied areas in solar physics, its activity, such as flares, prominence eruptions and CMEs, is far from understood. Since the solar corona is a low-ß plasma, its structure and dynamics are driven by the magnetic field. The aim of this PhD thesis to study the magnetic field in the solar corona. Unfortunately, high quality direct measurements of the coronal magnetic field are not available and theoretical extrapolation using the observed photospheric magnetic field is required. The thesis is mainly divided in two parts. The first part deals with the comparison between theoretical models of magnetic fields and observed structures in the corona. For any theoretical model, a quantitative method to fit magnetic field lines to observed coronal loops is introduced. This method provides a quantity C that measures how closely a theoretical model can reproduce the observed coronal structures. Using linear force-free field extrapolation, the above field line fitting method is used to study the evolution of an active region. The method is also illustrated when the theoretical magnetic field depends on more than one parameter. The second part of the thesis focuses on the linear force-free field assumption using two different geometric configurations. Firstly a vertical rigid magnetic flux tube is considered. The analytical expression of the magnetic field is obtained as an expansion in terms of Bessel functions. The main properties of this system are discussed and compared with two cylindrically symmetric twist profiles. For the second system, the photosphere is assumed to be an infinite plane. Using translational geometry, the analytical expression of the linear force-free magnetic field that matches a prescribed line of sight magnetic field component is obtained. This solution is compared with the non-linear solution obtained by Roumeliotis (1993).
57

Functional Modeling of C2

Prytz, Erik January 2009 (has links)
Command and Control (C2) refers to the process or function of commanding and controlling military or civilian units. For most military context C2 is exercised in an adversarial environment where two or more forces are fighting against each other. In these situations it is desirable to constrain the adversarial forces in order to prevent them from achieving their objectives. By maintaining an accurate view of the possible dependencies and couplings within the own forces and between the own and adversarial forces, constraints can be managed and coordinated. The purpose of this thesis is to develop a model that is capable of capturing these dependencies and couplings. This model is developed using the Functional Resonance Analysis Method (FRAM; Hollnagel, 2004). FRAM builds on the assumption that all parts of the system can be described as functional units. These functional units can then be linked together to form large systems. The links themselves are defined by how a function may affect other functions or in turn be affected by them. This enables the model to incorporate complex interactions within the system as well as between two adversarial systems. The microworld “Dynamiskt Krigsspel för Experiment” (DKE) was used to develop the model. A scenario with two teams battling in this adversarial microworld setting was analyzed in detail for this purpose. The developed model uses three different layers, or resolutions, of functions to capture all potential couplings between functions. The lowest level of functions, called the tactical level, is the physical actions of the units in the microworld. The next level, the operational level, concerns the more overarching goals for which the tactical functions are used. Last, the strategic level consists of the C2 functions, such as data collection, sensemaking and planning. The developed model is then applied to the scenario in DKE and shown to be able to describe and explain all actions by the two adversary systems as well as the couplings and dependencies between them.
58

Simulace přenosu DVB-C a DVB-C2 a jejich vzájemné porovnání / Simulation of the DVB-C and DVB-C2 transmission and their comparison

Cibulka, Tomáš January 2013 (has links)
This Master thesis deals with description, analysis and simulation of standards of digital video broadcasting DVB-C and DVB-C2. There is described mainly the transmission system, channel coding, type of modulation and OFDM symbols generation. Furthermore, channel models, used for the exploring of their performances are described too. There was created an application with a graphical interface in MATLAB, which simulates transmission in DVB-C2. Based on simulations there are compared influences of each settings on bit error rate of data transmission for both standards. Finally, obtained simulation results are compared with theoretical values.
59

Fullerene im Strahlungsgleichgewicht - Untersuchungen in einem Quadrupolspeicher

Decker, Silvio 11 August 2009 (has links)
Das wissenschaftliche Ziel der Arbeit ist die Untersuchung von optischen und chemischen Eigenschaften von kohlenstoffhaltigen Teilchen im besonderen Fullerene bei hohen Temperaturen. Die Arbeit behandelt im Detail den Aufbau und die Charakterisierung einer Messapparatur zur Untersuchung von Fulleren-Kationen. Nach einer kurzen Einführung zum Thema und einer Beschreibung des Aufbaus der Arbeit beginnt diese mit der Charakterisierung der Apparatur als Ganzes und ihrer Elemente. Dazu gehört die weiterentwickelte Sublimationsionenquelle, der Quadrupolspeicher und der Ionendetektor. Es werden eingehende Messungen zur Speicherung und zum Nachweis der absoluten Zahl von gespeicherten Ionen vorgestellt. Weiterhin wird das optische Nachweissystem bezüglich der Sammelleistung und des Empfindlichkeit eingehend untersucht. Nach der Einführung in die Apparatur wird die Verteilung der Ionen im Speicher näher beleuchtet und gezeigt, dass ein optischer Nachweis der Zahl gespeicherter Ionen möglich ist. Außerdem wird gezeigt, dass es gelingt die kinetische Temperatur der Ionen im Speicher, durch die geometrische Vermessung der Ionenverteilung zu bestimmen. Im weiteren wird auf die thermische Emission heißer C60+ näher eingegangen. Dazu wird ein klassisches dielektrisches Modell zur thermischen Emission vorgestellt. Es werden Messprinzipien zur Temperaturbestimmung der lasergeheizten Ionen erörtert und Messungen zur Temperatur des Ionenensembles präsentiert. Weiterhin werden Messungen zum C2-Verlust von C60+ als Funktion der Temperatur vorgestellt. Die experimentell ermittelte Aktivierungsenergie der C2-Verlustreaktion mit Ea = 2,3...5,4eV zeigt deutliche Abweichungen zu bekannten Literaturwerten. Die Ergebnisse dieser Messung werden mit einer nummerischen Simulation zur Energieverteilung im Ionenensemble diskutiert. Die Arbeit endet mit einer Zusammenfassung und einem Ausblick auf weitere experimentelle Möglichkeiten der Messmethode. Ersetzt durch neues Dokument, wegen URL auf Titelseite. / The scientific goal of this work is the study of optical and chemical properties of carbon containing particles especially fullerenes at high temperatures. This work covered the construction and characterization of the measuring apparatus for the investigation of fullerene cations. It follows a characterization of the apparatus and its elements after a short introduction and a description of the structure of this work. This involved the further developed sublimation ion source, the quadrupole trap and the ion detections system. Extensive measurements of the ion trapping and the proof of the absolute number of trapped ions are presented. Further on the optical detections system is characterized in depth regarding the collection efficiency and sensitivity. After the introduction in the apparatus the distribution of the ions inside the trap is closer examined. The possibility of the optical detections of the number of trapped ions is shown. Additionally it is pointed out that the kinetic temperature of the ions can be extracted by geometrical measurement of the ion distribution. Further on it is enlarged on the thermal emission of hot C60. For this a classical dielectric model for the thermal emission is presented. Measuring principals of the temperature determination of laser heated ions are discussed and temperature measurements of the ion ensemble are presented. Measurements of the C2-loss as function of the temperature are presented. The results of the extracted activation energy of Ea = 2.3...5.4eV for the C2-loss reaction of C60+ shows a discrepancy to literature results. The results of this measurements are discussed with help of an numerical simulation of the internal energy distribution of the ion ensemble. This work closes with a summery and an outlook of further experimental potentialities of the measuring method. Replaced by new document, because of URL on the title page.
60

Fullerene im Strahlungsgleichgewicht - Untersuchungen in einem Quadrupolspeicher

Decker, Silvio 11 August 2009 (has links)
Das wissenschaftliche Ziel der Arbeit ist die Untersuchung von optischen und chemischen Eigenschaften von kohlenstoffhaltigen Teilchen im besonderen Fullerene bei hohen Temperaturen. Die Arbeit behandelt im Detail den Aufbau und die Charakterisierung einer Messapparatur zur Untersuchung von Fulleren-Kationen. Nach einer kurzen Einführung zum Thema und einer Beschreibung des Aufbaus der Arbeit beginnt diese mit der Charakterisierung der Apparatur als Ganzes und ihrer Elemente. Dazu gehört die weiterentwickelte Sublimationsionenquelle, der Quadrupolspeicher und der Ionendetektor. Es werden eingehende Messungen zur Speicherung und zum Nachweis der absoluten Zahl von gespeicherten Ionen vorgestellt. Weiterhin wird das optische Nachweissystem bezüglich der Sammelleistung und des Empfindlichkeit eingehend untersucht. Nach der Einführung in die Apparatur wird die Verteilung der Ionen im Speicher näher beleuchtet und gezeigt, dass ein optischer Nachweis der Zahl gespeicherter Ionen möglich ist. Außerdem wird gezeigt, dass es gelingt die kinetische Temperatur der Ionen im Speicher, durch die geometrische Vermessung der Ionenverteilung zu bestimmen. Im weiteren wird auf die thermische Emission heißer C60+ näher eingegangen. Dazu wird ein klassisches dielektrisches Modell zur thermischen Emission vorgestellt. Es werden Messprinzipien zur Temperaturbestimmung der lasergeheizten Ionen erörtert und Messungen zur Temperatur des Ionenensembles präsentiert. Weiterhin werden Messungen zum C2-Verlust von C60+ als Funktion der Temperatur vorgestellt. Die experimentell ermittelte Aktivierungsenergie der C2-Verlustreaktion mit Ea = 2,3...5,4eV zeigt deutliche Abweichungen zu bekannten Literaturwerten. Die Ergebnisse dieser Messung werden mit einer nummerischen Simulation zur Energieverteilung im Ionenensemble diskutiert. Die Arbeit endet mit einer Zusammenfassung und einem Ausblick auf weitere experimentelle Möglichkeiten der Messmethode. / The scientific goal of this work is the study of optical and chemical properties of carbon containing particles especially fullerenes at high temperatures. This work covered the construction and characterization of the measuring apparatus for the investigation of fullerene cations. It follows a characterization of the apparatus and its elements after a short introduction and a description of the structure of this work. This involved the further developed sublimation ion source, the quadrupole trap and the ion detections system. Extensive measurements of the ion trapping and the proof of the absolute number of trapped ions are presented. Further on the optical detections system is characterized in depth regarding the collection efficiency and sensitivity. After the introduction in the apparatus the distribution of the ions inside the trap is closer examined. The possibility of the optical detections of the number of trapped ions is shown. Additionally it is pointed out that the kinetic temperature of the ions can be extracted by geometrical measurement of the ion distribution. Further on it is enlarged on the thermal emission of hot C60. For this a classical dielectric model for the thermal emission is presented. Measuring principals of the temperature determination of laser heated ions are discussed and temperature measurements of the ion ensemble are presented. Measurements of the C2-loss as function of the temperature are presented. The results of the extracted activation energy of Ea = 2.3...5.4eV for the C2-loss reaction of C60+ shows a discrepancy to literature results. The results of this measurements are discussed with help of an numerical simulation of the internal energy distribution of the ion ensemble. This work closes with a summery and an outlook of further experimental potentialities of the measuring method.

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