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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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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.
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Showing 141 to 150 of 212 (0.275 seconds)Spelling suggestions: "subject:"1technische universität chemnitz"" "subject:"1technische universität chemnnitz""
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Optimal Control Problems in Finite-Strain Elasticity by Inner Pressure and Fiber TensionGünnel, Andreas, Herzog, Roland 01 September 2016 (has links)
Optimal control problems for finite-strain elasticity are considered. An inner pressure or an inner fiber tension is acting as a driving force. Such internal forces are typical, for instance, for the motion of heliotropic plants, and for muscle tissue. Non-standard objective functions relevant for elasticity problems are introduced. Optimality conditions are derived on a formal basis, and a limited-memory quasi-Newton algorithm for their solution is formulated in function space. Numerical experiments confirm the expected mesh-independent performance.
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Parameter Tuning for the NFFT Based Fast Ewald SummationNestler, Franziska 14 September 2016 (has links)
The computation of the Coulomb potentials and forces in charged particle systems under 3d-periodic boundary conditions is possible in an efficient way by utilizing the Ewald summation formulas and applying the fast Fourier transform (FFT). In this paper we consider the particle-particle NFFT (P2NFFT) approach, which is based on the fast Fourier transform for nonequispaced data (NFFT) and compare the error behaviors regarding different window functions, which are used in order to approximate the given continuous charge distribution by a mesh based charge density. Typically B-splines are applied in the scope of particle mesh methods, as for instance within the well-known particle-particle particle-mesh (P3M) algorithm. The publicly available P2NFFT algorithm allows the application of an oversampled FFT as well as the usage of different window functions. We consider for the first time also an approximation by Bessel functions and show how the resulting root mean square errors in the forces can be predicted precisely and efficiently. The results show that, if the parameters are tuned appropriately, the Bessel window function is in many cases even the better choice in terms of computational costs. Moreover, the results indicate that it is often advantageous in terms of efficiency to spend some oversampling within the NFFT while using a window function with a smaller support.
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Enhanced Passive RF-DC Converter Circuit Efficiency for Low RF Energy HarvestingChaour, Issam, Fakhfakh, Ahmed, Kanoun, Olfa 02 May 2017 (has links) (PDF)
For radio frequency energy transmission, the conversion efficiency of the receiver is decisive not only for reducing sending power, but also for enabling energy transmission over long and variable distances. In this contribution, we present a passive RF-DC converter for energy harvesting at ultra-low input power at 868 MHz. The novel converter consists of a reactive matching circuit and a combined voltage multiplier and rectifier. The stored energy in the input inductor and capacitance, during the negative wave, is conveyed to the output capacitance during the positive one. Although Dickson and Villard topologies have principally comparable efficiency for multi-stage voltage multipliers, the Dickson topology reaches a better efficiency within the novel ultra-low input power converter concept. At the output stage, a low-pass filter is introduced to reduce ripple at high frequencies in order to realize a stable DC signal. The proposed rectifier enables harvesting energy at even a low input power from −40 dBm for a resistive load of 50 kΩ. It realizes a significant improvement in comparison with state of the art solutions
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Experimental observation and quantum chemical investigation of thallium(I) (Z)-methanediazotate: synthesis of a long sought and highly reactive speciesSingh, Neeraj, Fiedler, Benjamin, Friedrich, Joachim, Banert, Klaus 28 April 2017 (has links) (PDF)
For the first time, successful synthesis and characterisation of the missing (Z)-isomer of thallium(I) methanediazotate has been accomplished, utilising low-temperature NMR monitoring analysis. The title compound was synthesised from N-methyl-N-nitrosourea and thallium(I) propoxide, under sub-ambient temperature conditions, as a highly moisture sensitive entity. Quantum chemical calculations, performed at the CCSD(T) level, depict excellent conformity to experimental results. Indeed, compared to its (E) counterpart, the formation of the title compound is thermodynamically less favoured, but preferred by means of kinetic control owing to a hindered isomerisation.
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Surface- and tip-enhanced resonant Raman scattering from CdSe nanocrystalsSheremet, E., Milekhin, A. G., Rodriguez, R. D., Weiss, T., Nesterov, M., Rodyakina, E. E., Gordan, O. D., Sveshnikova, L. L., Duda, T. A., Gridchin, V. A., Dzhagan, V. M., Hietschold, M., Zahn, D. R. T. 27 February 2015 (has links) (PDF)
Surface- and tip-enhanced resonant Raman scattering (resonant SERS and TERS) by optical phonons in a monolayer of CdSe quantum dots (QDs) is demonstrated. The SERS enhancement was achieved by employing plasmonically active substrates consisting of gold arrays with varying nanocluster diameters prepared by electron-beam lithography. The magnitude of the SERS enhancement depends on the localized surface plasmon resonance (LSPR) energy, which is determined by the structural parameters. The LSPR positions as a function of nanocluster diameter were experimentally determined from spectroscopic micro-ellipsometry, and compared to numerical simulations showing good qualitative agreement. The monolayer of CdSe QDs was deposited by the Langmuir–Blodgett-based technique on the SERS substrates. By tuning the excitation energy close to the band gap of the CdSe QDs and to the LSPR energy, resonant SERS by longitudinal optical (LO) phonons of CdSe QDs was realized. A SERS enhancement factor of 2 × 10<sup>3</sup> was achieved. This allowed the detection of higher order LO modes of CdSe QDs, evidencing the high crystalline quality of QDs. The dependence of LO phonon mode intensity on the size of Au nanoclusters reveals a resonant character, suggesting that the electromagnetic mechanism of the SERS enhancement is dominant. Finally, the resonant TERS spectrum from CdSe QDs was obtained using electrochemically etched gold tips providing an enhancement on the order of 10<sup>4</sup>. This is an important step towards the detection of the phonon spectrum from a single QD. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Cognitive Investments in Academic Success: The Role of Need for Cognition at UniversityGrass, Julia, Strobel, Alexander, Strobel, Anja 26 June 2017 (has links) (PDF)
Previous research has shown that Need for Cognition (NFC), the individual tendency to engage in and enjoy cognitive endeavors, contributes to academic performance. Most studies on NFC and related constructs have thereby focused on grades to capture tertiary academic success. This study aimed at a more comprehensive approach on NFC’s meaning to success in university. We examined not only performance but also rather affective indicators of success. The current sample consisted of 396 students of different subjects with a mean age of 24 years (139 male). All participants took part in an online survey that assessed NFC together with school performance and further personality variables via self-report. Success in university was comprehensively operationalized including performance, satisfaction with one’s studies, and thoughts about quitting/changing one’s major as indicators. The value of NFC in predicting tertiary academic success was examined with correlation analyses and path analysis. NFC significantly correlated with all success variables with the highest correlation for study satisfaction. Path analysis confirmed the importance of NFC for study satisfaction showing that NFC had a significant direct effect on study satisfaction and via this variable also a significant indirect effect on termination thoughts. This study clearly indicates that NFC broadly contributes to the mastery of academic requirements and that it is worthwhile to intensify research on NFC in the context of tertiary education.
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Open Access-Tag 2016 "Aktiv sein – etwas bewegen"Partmann, Michael 17 November 2016 (has links) (PDF)
Das vorliegende Grußwort wurde anlässlich des Open Access-Tages 2016 der Technischen Universität Chemnitz durch den Referenten (Schwerpunkt Forschung und wissenschaftlicher Nachwuchs) im Büro des Rektors der TU Chemnitz gehalten. Der Redner ging auf die zunehmende Bedeutung von Open Access ein und hob die diesbezüglichen Services der Universitätsbibliothek hervor. / The welcome speech was held on Open Access Day 2016 of Technische Universität Chemnitz by Michael Partmann, Assistant (specialized in Research and Junior Researchers) in the Rector’s Office. The speaker mentioned the increasing importance of Open Access and highlighted the relevant services of the University Library.
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Finanzierung von Open Access - bisher und heute / Open-Access-Funding - so far and nowBlumtritt, Ute 17 June 2013 (has links) (PDF)
Die Universitätsbibliothek Chemnitz bietet seit vielen Jahren verschiedene Services zum Open-Access-Publizieren für die Wissenschaftler der Technischen Universität.
Dazu gehören u.a. das digitale Volltextarchiv, das Open Journal System und der Universitätsverlag.
Wissenschaftliche Autoren können sowohl auf dem Goldenen als auch auf dem Grünen Weg Open Access publizieren.
In diesem Jahr wurde erstmals ein Publikationsfonds für die Veröffentlichung von Open-Access-Artikeln eingerichtet. Es wurden Mittel von der Deutschen Forschungsgemeinschaft und der Technischen Universität Chemnitz bereitgestellt.
Damit können die Universitätsangehörigen die finanzielle Übernahme von Publikationsgebühren für Open-Access-Artikel bei der Bibliothek beantragen.
Sind die Fördervoraussetzungen erfüllt, erfolgt der Zuschlag in der Reihenfolge des Eingangs der Rechnung. / Since many years the University Library of Chemnitz offers several services regarding open access publication to the scientists of Chemnitz University of Technology.
Among others this includes a digital archive, a Journal Management System, and the University Press.
It is possible to publish on Golden Way of Open Access as well as on Green Way.
This year we offer for the first time a publication funds for the publication of open access articles.
The financial resources are provided by Deutsche Forschungsgemeinschaft and Chemnitz University of Technology.
Please apply for financial support at the University Library if you need to pay a publication fee for open access articles.
If the criteria for financial support are met an agreement will be made in order of invoices received.
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Wissen.Auf den Punkt - Das Jahrbuch der Technischen Universität Chemnitz / Knowledge.On the point - The yearbook of Technische Universität Chemnitz18 November 2014 (has links)
Das Jahrbuch der TU Chemnitz erscheint einmal jährlich und gibt einen Rück- und Ausblick auf die Entwicklung der Universität. / The yearbook of TU Chemnitz is published once a year and gives retrospect and perspective of the development of the university.
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How Well Can Saliency Models Predict Fixation Selection in Scenes Beyond Central Bias? A New Approach to Model Evaluation Using Generalized Linear Mixed ModelsNuthmann, Antje, Einhäuser, Wolfgang, Schütz, Immo 22 January 2018 (has links) (PDF)
Since the turn of the millennium, a large number of computational models of visual salience have been put forward. How best to evaluate a given model's ability to predict where human observers fixate in images of real-world scenes remains an open research question. Assessing the role of spatial biases is a challenging issue; this is particularly true when we consider the tendency for high-salience items to appear in the image center, combined with a tendency to look straight ahead (“central bias”). This problem is further exacerbated in the context of model comparisons, because some—but not all—models implicitly or explicitly incorporate a center preference to improve performance. To address this and other issues, we propose to combine a-priori parcellation of scenes with generalized linear mixed models (GLMM), building upon previous work. With this method, we can explicitly model the central bias of fixation by including a central-bias predictor in the GLMM. A second predictor captures how well the saliency model predicts human fixations, above and beyond the central bias. By-subject and by-item random effects account for individual differences and differences across scene items, respectively. Moreover, we can directly assess whether a given saliency model performs significantly better than others. In this article, we describe the data processing steps required by our analysis approach. In addition, we demonstrate the GLMM analyses by evaluating the performance of different saliency models on a new eye-tracking corpus. To facilitate the application of our method, we make the open-source Python toolbox “GridFix” available.
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