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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.
11

129-Xe-NMR-spektroskopische Untersuchungen an Carbon Black und Graphit - 129Xe NMR Spectroscopy of Carbon Black and Graphite

Schmidt, Holger 24 February 2003 (has links)
Porous Carbon Blacks with specific surfaces of up to 1475 m²/g were examined and characterized by <sup>129</sup>Xe NMR spectroscopy. Graphite is regarded as a not-porous reference. The porosity of Carbon Blacks can be divided in three categories: inter-aggregate, intra-aggregate and intra-particle pores. A reciprocal behavior of the chemical shift to the middle pore radius has been found. Here the pressure and temperature dependence of the chemical shift are to be considered and only with pressures over 8-12 bar a characteristic limit value is reached. The diffusion coefficient of the intra-porous xenon atoms was determined with the help of the PFG NMR spectroscopy and lies with ambient temperature and a pressure from 10 to 12 bar within the range of 3·10<sup>-9</sup> to 3·10<sup>-8</sup>m²/s. The adsorption in micro-porous Carbon Blacks can be described by the pore filling theory of Dubinin and co-workers.
12

Politik und Organspende : eine Untersuchung zur politischen Umsetzung gesetzgeberischer Intentionen in der Gesundheitsversorgung / Politics and Organ Donation : a survey of the political implementation of the first German Transplantation Act

Nitsche, Markus 23 February 2005 (has links)
In Germany the procurement, distribution und transplantation of cadaveric human organs is understood as a public task. The institutionalization of a specific law on transplantation fall in with a picture of a growing government intervention in all parts of human life, which original had been organized individually by the members of society itselves. From a classical liberal point of view and in consideration of the principle of subsidiarity the institutionalization of a specific law on transplantation is wether a deserving process nor it had been necessarily implemented. The statistic data of organ donation in germany show that the expected increase of the number of available cadeveric organs as an assumed positive result of the new transplantation act - failed to appear so far. Moreover we have to notice that the politicians who are responsible for an adequate implementation of the legal conditions haven`t attended to their duties. As long as the official policy only accept altruistic motivation as an incentive to donate cadaveric organs the status quo won`t change. In these circumstances a slowly reduce of government intervention maybe leeds to a better policy on organ donation. This kind of policy should give people the chance to help themselves in using other incentives than the motive of altruistic help.
13

Informationserfassung durch galvanomagnetische und strukturierte Komponenten in Sensorsystemen - Acquisition of information by galvanomagnetic and structured components in sensor systems

Pitsch, Holger 02 March 2004 (has links)
The high degree of automation in industrial manufacturing and in many areas of the daily life requires as well as the continuous rising need for information of the society an technical measurement monitoring of various process and environmental parameters. Sensors convert the instantaneous value of a physical measured variable on basis of physical or chemical effects into an equivalent electrical signal. They build the interface between a technical system and its environment. Magnetic field sensors, like the sensor elements Hall-Element and magneto-resistor which are based on galvanomagnetic ef-fects, react to a magnetic interaction with the item under test or cause such an interac-tion. The starting point of the present study is built by the treatment of the components of galvanomagnetic sensor systems as shape elements out of defined material, which are used as information carrier by modification of the constructional parameters. The variation of number, arrangement and/or geometrical shape results in one- or multidi-mensionally structured system components, which allow the generation of defined sen-sor system topologies with custom-designed information content. Within the framework of this work different new sensor systems were developed, which open a broader appli-cation scope to the galvanomagnetic sensor technology by structured components and which permit the application of these sensors within purviews of the measuring tech-nique, which are dominated so far by sensors on basis of other, usually optical effects. If the allocation of a sensor signal to the structure of a system component is reproducible and biunique, then the principle of the structure variation also admits a purposeful cod-ing of defined discrete information. For this a beginning for the development of magnetic structure codes for the identification technology forms the conclusion of this thesis.
14

Monolithische Integration von Heterostruktur-Bipolartransistoren und Elektroabsorptionsmodulatoren auf InP - Monolithic integration of heterojunction bipolar transistors and electroabsorption modulators on InP

Reimann, Thorsten 05 March 2004 (has links)
This work explains a method for optoelectronic integration of an heterojunction bipolar transistor (HBT) and a waveguide electroabsorption modulator (EAM). For this the epitactical layers of the individual devices based on III/V-semiconductors are merged into each other. The method has the advantage to reuse layers and results in a layer stack, which is easier to process technologically. Additionally to the manufacturing of the individual devices HBT and EAM, this integration enables a multifunctional device, which works in the optical and electronic regime simultaneously (HBT-EAM). This corresponds to an EAM with integrated amplifier. Presented are epitaxy, technological processing and measurement results.
15

Neue Methoden zur Feststoffanalytik unter Einsatz eines Induktiv gekoppelten Plasma-Massenspektrometers (ICP-MS) - New Methods in solid analysis for Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

Maibusch, Ralf 11 March 2003 (has links)
The main point of this thesis is the validation of SA-ICP-MS for routine analysis in the steel industry. Therefor a new interface-system is build up in order to measure transient siganls from the continuos ablation process of the spark device. Further more the coupling of an ETV oven for slurry analysis and a Laser Ablation for isitope ratio determination is discriebed. Some fundamental aspects in formation of interference in ICP-MS are pointed out at the end of this thesis.
16

Regionale Integration in Asien - Regional integration in Asia - Duisburger Arbeitspapiere zur Ostasienwirtschaft 67(2003)

Fischer, Doris 09 March 2004 (has links)
In the past, regional integration in Asia has basically been limited to market-driven economic integration and private networking. Policy-driven or institutional co-operation and integration have been very limited. The Asian financial crisis as well as the introduction of the Euro has contributed to a change in this pattern. A growing awareness of the advantages of regional co-operation is discernible among Asian states. The Chiang Mai initiative and numerous regional trade agreements are the most visible results of this growing awareness. Nevertheless it is to be doubted that this awareness will transform into concrete and higher level institutional integration among Asian states within the near future. The paper summarises the progress achieved so far in regional co-operation and integration and discusses the main factors favouring and limiting future perspectives.
17

Direkte Bestimmung von Eisenspuren in Dichlorsilan mit Hilfe der Graphitrohrofen-Atomabsorptionsspektrometrie (GF-AAS) - Direct Determination of Trace Amounts of Iron in Dichlorosilane by Graphite Furnace Atomic Absorption Spectrometry (GF-AAS)

Benninghoff, Claus 11 March 2004 (has links)
In the present thesis the development of an analytical method for the determination of trace amounts of iron in dichlorosilane by graphite furnace atomic absorption spectrometry with a modified autoprobe unit is described. An conceived gas inlet system enabled a nearly contamination free and constant gas injection. The analytical method is optimized and the iron concentration in dichlorosilane is quantitatively determined.
18

Digitale CMOS-Photodetektormatrizen mit integrierten A/D-Wandlern / Digital CMOS-Photodetector Matrices with Integrated A/D-Converters

Gnade, Michael 16 March 2004 (has links)
In the field of radiological diagnostics, especially for the computed tomography a large number of photodetector elements (so called Pixels) is needed to assemble a large-area X-Ray-sensitive detector. These pixels should provide very high sensitivity, a very large dynamic range and a high signal-to-noise-ratio. Moreover, an in-pixel digitization of the signals is desired. To meet these specifications, a digital CMOS-Pixel comprising a special type of photodiode and a single-loop sigma-delta-modulator was developed, theoretically analyzed, fabricated and characterized. A matrix of 4x4 digital CMOS-pixels with each of them consuming an area of 1mm² has been fabricated. For further signal processing the concept of a multichannel decimation filter is presented.
19

LED-Mikrodisplays für intraokulare Sehhilfen / LED-microdisplays for intraocular vision aids

Puettjer, Dirk 20 March 2006 (has links)
This dissertation introduces an implantable LED microdisplay in the aim of returning a certain ability to see to blind people. The microdisplay is the basic device of the intraocular vision aid (IoVA) an implant developed for those whose cornea of the eye is considerably blurred due to accident or illness. This microdisplay consists of a LED-array which is connected to a CMOS driver circuit. By means of activating each pixel an image of the surroundings is generated and directly projected onto the retina. Within the scope of this dissertation the concepts and techniques of the intraocular vision aid are described. Physiological and technical parameters for application of the microdisplay are explained. That followed the material and applied technologies are defined. Finally the technological realization of the LED microdisplay is demonstrated as well as the first functional model on a worldwide scale.
20

Krümmungsabschätzungen für stabile Extremalen parametrischer Funktionale / Curvature estimates for stable extremals of parametric functionals

Winklmann, Sven 22 March 2004 (has links)
We consider immersed hypersurfaces in euclidean $R^{n+1}$ which are stable with respect to an elliptic parametric functional with integrand $F=F(N)$ depending on normal directions only. We prove an integral curvature estimate provided that $F$ is sufficiently close to the area integrand, extending the classical curvature estimate of Schoen, Simon and Yau for stable minimal hypersurfaces in $R^{n+1}$. As a crucial point of our analysis we derive a generalized Simons inequality for the laplacian of the length of a weighted second fundamental form with respect to an abstract metric associated with $F$. Using Moser's iteration technique we finally prove a pointwise curvature estimate for $n leq 5$. As an application we obtain a new Bernstein result for complete stable hypersurfaces of dimension $n leq 5$.

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