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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.
241

Free electron laser spectroscopy of narrow gap semiconductors

Findlay, Peter Charles January 2000 (has links)
No description available.
242

Catalyzed hydrogenation of nitrogen and ethylene on metal (Fe, Pt) single crystal surfaces and effects of coadsorption A sum frequency generation vibrational spectroscopy study.

Westerberg, Staffan Per Gustav January 2004 (has links)
Thesis (Ph.D.); Submitted to the University of California, Berkeley, Berkeley, California (US); 15 Dec 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--56814" Westerberg, Staffan Per Gustav. USDOE Director. Office of Science. Office of Basic Energy Sciences (US) 12/15/2004. Report is also available in paper and microfiche from NTIS.
243

The role of defects on Schottky and Ohmic contact characteristics for GaN and AlGaN/GaN high-electron mobility transistors

Walker, Dennis Eugene, January 2006 (has links)
Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 209-217).
244

Previsão de recalque e análise de confiabilidade de fundações em estacas hélice contínua / Prediction of settlements and reliability analysis of continuous flight auger piles

Nestor Benedito Fracasse de Barros 02 July 2012 (has links)
Esta dissertação apresenta uma avaliação do comportamento de estacas hélice contínua quanto à capacidade de carga, ao recalque e à segurança e confiabilidade, a partir de um cenário de análise em que foi considerado um banco de dados de 58 provas de carga estáticas, realizadas em estacas hélice contínua de 13 obras distintas. Esta pesquisa está focada principalmente no comportamento carga-recalque e confiabilidade de fundações em estacas hélice contínua. Nesta análise foi também verificada a aplicabilidade do método proposto por Aoki (1989) para determinação da curva carga-recalque destas provas de carga. Os valores de capacidade de carga medidos foram comparados com os previstos pelos método Aoki & Velloso (1975), o método Decourt & Quaresma (1978), o método de Cabral (1996), e o método Alonso (1996). Estes métodos também foram utilizados para previsão de transferência de carga nas estacas, necessária para a previsão da curva carga-recalque pelos método de Aoki (1989). Adicionalmente, com os resultados das provas de carga foram estimadas para cada obra a probabilidade de ruína da fundação, e de ocorrência de recalques superiores a um valor limite. / This dissertation presents an evaluation of the behavior of continuous flight auger piles on ultimate capacity, settlments, safety and reliability, from a scenario analysis in which we considered a database of 58 static load tests, performed on piles of 13 distinct sites. However, this research is focused on the loaddisplacement behavior and reliability of this type of foundation. This analysis also verified the applicability of the method proposed by Aoki (1989) to determine the load-displacement curve of these pile load tests. The values of measured pile capacity were compared with those provided by the method Aoki & Velloso (1975), the method Decourt & Quaresma (1978), the method Cabral (1996), and the method Alonso (1996). These methods were also used to predict the load transfer along the piles, necessary to predict the load-displacement curve by the method of Aoki (1989). Additionally, the results of these load tests were used to estimate the probability of failure of the foundations tested, and the occurrence of settlements exceeding a threshold value.
245

Effets thermoélectrique et photovoltaïque dans les cellules solaires à porteurs chauds / Thermoelectric and photovoltaic effects in hot carrier solar cells

Gibelli, François René Jean 25 November 2016 (has links)
La cellule solaire à porteurs chauds est un dispositif à haut rendement de conversion qui permettrait de réduire significativement le coût de l’énergie qu’il génère. Ces cellules fonctionnent avec des électrons et des trous en non-équilibre thermique avec le réseau cristallin du materiau grâce à la réduction des pertes d’énergie des porteurs, nécessitant le développement de contacts électriques sélectifs en énergie des porteurs en non-équilibre. La conception des contacts sélectifs nécessite une bonne connaissance des propriétés des porteurs dans le matériau considéré. Une méthode permettant de séparer les propriétés de chaque porteur par l’analyse de spectres de photoluminescence du matériau est proposée. Disposant de mesures de photoluminescence résolues spatialement, une seconde méthode a été développée pour approcher les coefficients de transport de chaque porteur dans le matériau : ces coefficients sont mesurés en une seule fois, par une méthode optique sans contacts. Ensuite le fonctionnement des contacts sélectifs est détaillé, démontrant la difficulté d’une stabilité électrique du système en courant continu, contrairement aux dispositifs photovoltaïques classiques. Quelques pistes de fabrication expérimentales avec des molécules et des boîtes quantiques colloïdales ont également été étudiées. Enfin, en combinant les résultats de ces travaux sur le semiconducteur photosensible et sur les contacts, un modèle de simulation a été développé. Il intègre les principaux mécanismes de pertes des porteurs, résultant ainsi en une généralisation de différents modèles précédemment étudiés dans la littérature. Un lien entre le dispositif étudié et les machines thermiques est proposé. / The hot carrier solar cell is a high conversion yield device that could enable to significantly reduce thecost of the energy it generates. Unlike classical photovoltaic devices, these cells work with electronsand holes in thermal non-equilibrium with the lattice of the material, due to the reduction of thelosses by thermalization. This specific feature require the development of energy selective contacts fornon-equilibrium carriers. The design of energy selective contacts require a good knowledge of the carrier properties in the considered material. A method enabling to separate the properties of each carrier with the analysis of photoluminescence spectra of the material is proposed. Having spatially resolved photoluminescence measurements, a second method has been developed to estimate the transport coefficients of each carrier in the material: these coefficients are measured with a one-probe optical contactless technique. Then the working principle of the energy selective contacts is studied, showing thereby the challenge of a direct current electrical stability of the system, unlike classical photovoltaïc devices. Some experimental manufacturing with molecules and colloidal quantum dots have also been studied. Last, combining the obtained results on the semiconductor and on the contacts, a modeling tool breaking the symmetry between carriers has been developed. The model takes two principal loss mechanisms of the carrier into account, leading thereby to a generalization of different models previously studied in the literature. More global thermodynamic aspects also show the link between the studied device and the heat engines.
246

Zlepšení toku hmoty obilné žací lišty typu Power Flow / Crop flow improvements at the Power Flow header

Štelcl, Michael January 2017 (has links)
The master's thesis is focused on a design of optimal working speed of auger and belt transporter which are parts of Power Flow header for standard type of combine harvester. In the master's thesis author suggest a new simplified theory of crop flow inside the Power Flow header. The thesis contain the factors which can affect the crop flow and comparison between the Power Flow and competitor's header. The thesis also contain geometrical characteristics of crop for four types of cereal.
247

Interpretation and relativistic simulation of selected electronic transitions:decays of M-shell hole states in atomic Cr, Br and Rb

Keskinen, J. (Juho) 28 November 2019 (has links)
Abstract In this thesis electronic structure of atomic chromium, rubidium and bromine are studied experimentally and theoretically through transitions and decay processes originating from selected M-shell hole states. The experiments are conducted with traditional methods of electron spectroscopy as well as more recent multicoincidence methods using pulsed synchrotron radiation and a magnetic bottle spectrometer. The observed electronic transitions are theoretically simulated with multiconfiguration Dirac-Fock method. Finally, the calculations are used to interpret the measured spectra to investigate the energy level structure and electron dynamics of the studied elements. / Original papers Original papers are not included in the electronically distributed version of the thesis. Keskinen, J., Huttula, S.-M., Mäkinen, A., Patanen, M., & Huttula, M. (2015). Experimental and theoretical study of 3p photoionization and subsequent Auger decay in atomic chromium. Radiation Physics and Chemistry, 117, 209–216. https://doi.org/10.1016/j.radphyschem.2015.08.018 Keskinen, J., Lablanquie, P., Penent, F., Palaudoux, J., Andric, L., Cubaynes, D., … Jänkälä, K. (2017). Initial-state-selected MNN Auger spectroscopy of atomic rubidium. Physical Review A, 95(4). https://doi.org/10.1103/physreva.95.043402 http://jultika.oulu.fi/Record/nbnfi-fe201706207380 Keskinen, J., Jänkälä, K., Huttula, S.-M., Kaneyasu, T., Hikosaka, Y., Shigemasa, E., … Lablanquie, P. (2019). Auger decay of the 3d hole in the isoelectronic series of Br*, Kr⁺ and Rb²⁺. Manuscript in preparation.
248

Spršky kosmického záření s anomálními podélnými profily / Cosmic ray showers with anomalous longitudinal profile

Blažek, Jiří January 2014 (has links)
Title: Cosmic Ray Showers with Anomalous Longitudinal Profile Author: Jiří Blažek Department: Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University Supervisor: RNDr. Petr Trávníček, Ph.D., Institute of Physics ASCR Abstract: The aim of this work was to study high-energy cosmic ray showers with anomalous longitudinal profiles generated by Monte-Carlo simulation and subse- quently use the acquired analysis techniques on results from the Pierre Auger Observatory (PAO) in Argentina. Firstly, a short introduction of various de- scriptions of the extensive air showers was given. Then a systematic analysis was performed on approx. 7 × 105 simulated showers with three different tech- niques. A brief explanation of the functionality of the PAO was given, then the importance of monitoring the immediate state of the atmosphere using the Shoot- the-Shower program was elucidated and the FRAM telescope was described in detail. FRAM enabled an identification of showers with a clear atmospheric back- ground, this sample of showers was then analyzed and several interesting events warranting a further study were chosen. Keywords: Pierre Auger Observatory, Extensive Air Showers, Chemical Compo- sition, Anomalous Longitudinal Profile, Gaisser-Hillas Function
249

Měření energetického spektra kosmického záření s využitím událostí bohatých na čerenkovské záření na Observatoři Pierra Augera / Measurement of the energy spectrum of cosmic rays using Cherenkov-dominated data at the Pierre Auger Observatory

Novotný, Vladimír January 2020 (has links)
This thesis presents the energy spectrum of cosmic rays deduced from Cherenkov-dominated data measured by the fluorescence detector of the Pierre Auger Observatory. Cherenkov-dominated events, used in the energy spectrum analysis at the Observatory for the first time, enable to decrease the energy threshold for the spectrum measurement down to 1015.5 eV. This energy is more than one order of magnitude lower than in preceding studies. The fluorescence detector was originally designed to detect the fluorescence light generated by extensive air showers in a hybrid mode with the surface detector of the Pierre Auger Observatory. The reconstruction of events dom- inated by Cherenkov light is available due to a newly developed reconstruc- tion technique, the profile constrained geometry fit. Its implementation in the Pierre Auger Observatory software is documented. Aspects of the energy spectrum analysis are described. They consist of exposure calculations done with the use of extensive Monte Carlo simulations, unfolding of the detec- tor effects, and inferring the invisible energy correction in the energy region below 1017 eV. Systematic uncertainties of the measurement are estimated. 1
250

Numerical Insights Into the Effect of Spacing on Axial Resistance of Auger Cast Piles

Correa Prada, Edgar Camilo 01 January 2023 (has links) (PDF)
The present thesis evaluates numerically and experimentally if the axial capacity of Auger Cast Piles (ACPs) constructed in interbedded layers of granular soil and Limestone should be reduced as a function of pile spacing. The numerical component of this thesis includes a series of parametric studies that consider different sets of normalized spacings, stiffness ratios, relative densities, unconfined compressive strengths, and installation effects for multiple subsurface conditions. The experimental program designed herein involves the construction of multiple components for a laboratory testing program of small-scale physical models that will validate the results of the numerical models in terms of capacities, efficiency ratios and normalized spacings.

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