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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.
111

A Re-Reanalysis of the Eötvös Experiment and Time-Variation of Nuclear Decay Rates

Michael J. Mueterthies (5930075) 15 August 2019 (has links)
<div> We consider the existence of a force that could produce a non-null result in the Eötvös experiment while producing a null result in the Eöt-Wash experiment. We introduce a general force, in the form of its Taylor series expansion, and determine the response of each experiment to that force. We can then determine which terms of the expansion are important to each experiment. A trial force, in the form of a mixed vector-scalar interaction is introduced and we analyze the resulting Eötvös parameters for various values of the strengths and ranges of the interactions. We find that under certain conditions the Eötvös parameter for the Eöt-Wash experiment can be made zero while the Eötvös parameter for the Eötvös experiment is nonzero.</div><div> </div><div><br></div><div> Next, we examine the possibility of a wind force appearing in the MICROSCOPE experiment. This wind would be due to the satellite's motion through a particle background which couples to the differential accelerometer through a baryon-number dependent interaction. We determine the signal that would be measured by MICROSCOPE satellite and compare the power spectrum density of this signal to the published power spectrum density of the experiment. </div><div> </div><div><br></div><div> Additionally, we present a new theoretical framework for the time-variation of nuclear decay rates. This new framework is motivated by the results of numerous experiments which show a periodicity of one year. The fractional decay rate of these experiments are constant, regardless of isotope. We find that a novel neutrino interaction, in the form of an index of refraction, successfully generates the constant fractional decay rates. Using the optical theorem and the relativistic Breit-Wigner distribution makes the index of refraction consistent with neutrino speed measurements. We conclude by describing other systems where the index of refraction could create observable oscillations.</div><div><br></div><div> </div><div> Finally, we consider the suppression of beta decay rates through the Pauli exclusion principle due to the presence of background cosmic and solar neutrinos. We derive the suppression factor for both thermalized and non-thermalized neutrinos.</div>
112

Formules de courant dans les systèmes mésoscopiques / Current formulas in mesoscopic systems

Gianesello, Céline 11 November 2011 (has links)
Le sujet principal de la thèse est le transport dans les systèmes mésoscopiques. Dans une première partie de lathèse, on étudie le cas d’un branchement adiabatique d’un biais de potentiel sur un système unidiensionnel sansrépartition initiale. On démontre que le courant complet est uniformément borné par rapport à la vitesse debranchement adiabatique, lorsque celle-ci tend vers zéro. On démontre l’existence de la partie linéaire de l’étatet du courant. La seconde partie de la thèse a donné lieu à a publication d’un article et elle consiste en l’étuded’un modèle discret, sans répartition initiale. On démontre que, dans ce système et après une perturbationélectrochimique, il existe un état stationnaire hors équilibre, et on retrouve la formule de Landauer-Büttikerpour ce modèle. La dernière partie de la thèse, qui a également donné lieu à un article, porte sur l’étude del’approximation des guides d’onde quantiques par des graphes quantiques. On s’intéresse à un guide d’ondelocalement torsadé. On étudie moins le Laplacien sur ce guide d’onde torsadé. Lorsque e diamètre du guidetend vers zéro et, simultanément, lorqsue le support de la courbure tend vers zéro, on démontre que le graphelimite est la ligne droite, et que l’opérateur limite est moins le Laplacien sur L2 (R) plus une condition deDirichlet à l’origine. Cette condition de Dirichlet est la conséquence des rétrécissements faits. En Annexe, ondonne des démonstrations et explications plus détaillées et utiles pour la compréhension de points clés de lathèse. / The main topic of the thesis is the transport in mesoscopic systems. In the first part of the work, we study thecase of a connection through an adiabatic potential on a one dimensional system without initial distribution, wesaid a “partition-free approach”. It is shown that the full current is uniformly bounded with respect to theadiabatic speed of connection, when it goes to zero. We prove the existence of the linear part of the state andcurrent. The second part of the thesis has led to publication of an article and deals with the study of a discretemodel without initial distribution. We prove that in this system and after an electrochemical disturbance thereexists a nonequilibrium steady state, and the Landauer-Büttiker formula is demonstrated for this model.The last part of the thesis, which also has led to an article, concerns the study of the approximation of quantumwaveguides by quantum graphs. We are interested in a waveguide locally twisted. We studyminus theLaplacian on this locally twisted waveguide. When the diameter of the guide goes to zero and simultaneouslywhen the support of the twisting goes to zero, we prove that the limit graph is the straight line, and the limitoperator is minus the Laplacian on the straight line plus a Dirichlet condition at the origin. The Dirichletcondition is the consequence of the shrinking done. In the appendix, we
113

Estudo da ação da clorpromazina na torção testicular em ratos / Role of chlorpromaxine in a model of testicular torsion

Mesquita, Rafael Carvalho 23 May 2016 (has links)
Introdução: A torção testicular permanece como uma emergência urológica, despertando grande interesse em fármacos que podem minorar a lesão testicular e suas repercussões na fertilidade e produção hormonal. No entanto, não há fármaco aprovado para uso clínico rotineiro. Uma droga estudada em isquemia celular é a clorpromazina, sendo conhecidos seus efeitos protetores na função e estrutura da membrana celular e mitocondrial. Objetivos: Avaliar a diferença na lesão de células germinativas após 1 e 6 horas de torção e a ação da clorpromazina administrada previamente à resolução da torção no testículo isquêmico. Materiais e Métodos: 54 ratos Wistar, machos, com peso corporal entre 220 e 260 gramas distribuídos em 5 grupos: sham, controle com isquemia de 1 hora(A), controle com isquemia de 6 horas(B), experimental com isquemia de 1 hora(C) e experimental com isquemia de 6 horas(D). Em 48 animais foi realizada torção unilateral do cordão espermático com duas voltas em torno do seu eixo (720 graus), fixando-se o testículo nessa posição, após o que cada subgrupo foi separado em avaliação imediata (orquiectomia bilateral ao final do período de torção = 1) e tardia (orquiectomia bilateral, uma semana após a resolução da torção = 2). O grupo experimental recebeu 3 mg/kg de clorpromazina administrada via endovenosa, 30 minutos antes da resolução da torção. O grupo controle recebeu apenas solução salina a 0,9% por via endovenosa. Outros 6 animais formaram o grupo sham, onde foi realizada apenas a manipulação do cordão espermático. Após retiradas as gônadas, foram preparadas para análise histológica pela microscopia de luz e imunohistoquímica.Um pequeno fragmento de cada testículo foi separado para avaliação por microscopia eletrônica de transmissão (MET). Resultados: Na análise por microscopia de luz foram notadas alterações devido à isquemia como, necrose de coagulação e edema intersticial, principalmente nos grupos com isquemia mais prolongada (6h - B e D). Na avaliação por imunohistoquímica, houve maior expressão da caspase-3 nas células e túbulos dos testículos com 6 horas de isquemia, quando comparados com o grupo sham. No entanto, a expressão de bcl-2 não foi expressiva em nenhum grupo. Os grupos B e D também demonstraram alterações mais expressivas na análise por MET. Em nenhuma das avaliações foi observado superioridade do grupo da clorpromazina em relação ao grupo controle. Conclusão: As lesões celulares intratubulares induzidas pela isquemia e reperfusão testicular foram semelhantes após 1 e 6 horas, as diferenças foram relacionadas à sua maior intensidade no grupo com 6 horas e a clorpromazina não foi efetiva na prevenção da lesão por reperfusão. / Introdution: Testicular torsion remains as a urology emergency arousing interest about medicine which can reduce testicular injury and its impact on fertility and hormone production. However, there is no drug approved for routine clinical use. A drug studied in cell ischemia is chlorpromazine, being known its protective effects on the function and structure of cellular membrane and mitochondrial. Objective: To evaluate the difference in lesion of germ cells after 1 and 6 hours and the action of chlorpromazine administered before the resolution of ischemic testicle due torsion. Materials and methods: 54 male Wistar rats weighing between 220 to 260 grams divided into five groups: sham, control with one hour of ischemia (A) control with six hours of ischemia (B) experimental with one hour of ischemia (C) and experimental six hours of ischemia (D). In 48 animals was performed unilateral torsion of the spermatic cord with two laps around its axis (720 degrees), keeping the testicle in this position. After that, each subgroup was divided into immediate evaluation (bilateral orchiectomy at end of the torsion period = 1) or later (bilateral orchiectomy after one week of torsion resolution = 2). The experimental group received 3 mg / kg chlorpromazine administered intravenously 30 minutes before the resolution of torsion. The control group received only saline 0.9% intravenously. Other 6 animals were in the sham group, which was held just handling the spermatic cord. After withdrawal, the gonads were prepared for histological analysis by light microscopy and immunohistochemistry. A small piece of each testis was separated for evaluation by electron microscopy. Results: In analysis by light microscopy, ischemic changes were rated as coagulative necrosis and interstitial edema mainly in groups with prolonged ischemia (6h - B and D). When analyzed by immunohistochemistry, there was greater expression of caspase-3 in cells and tubules of the testes with 6 hour of ischemia compared to the sham group. However, bcl-2 expression was not impressive in either group. B and D groups also showed more significant changes in the analysis by electron microscopy. None of the ratings has been shown superiority of chlorpromazine group over the control group. Conclusion: The germ cell damage induced by ischemia and reperfusion was similar after 1 and 6 hours, the differences were related to its greatest intensity in the group with 6 hours and chlorpromazine was not effective in preventing reperfusion injury.
114

Torção de Reidemeister das formas espaciais esféricas / Reidemeister torsion of spherical space forms

Melo, Thiago de 17 March 2009 (has links)
Neste trabalho, estudamos a ação dos grupos dos quatérnios generalizados \'Q IND.4t\', nas esferas, com o objetivo de calcularmos a torção de Reidemeister dos espaços quocientes, chamados de Formas Espaciais Esféricas Quaterniônicas. Calculamos a torção de Ray-Singer das esferas, dos espaços lenticulares e do cone sobre as esferas, este último fornecendo o caso particular do disco, usando a base para a homologia definida em [27]. Para as variedades fechadas, obtivemos a torção analítica por meio do Teorema de Cheeger-Müller [7, 22], e para o disco, por meio de uma fórmula provada por Brüning e Ma em [5] / In this work, we study the action of the generalized quaternionic groups \'Q IND.4t\' on the spheres to compute the Reidemeister torsion of the quotient spaces, which are called Quaternionic Spherical Space Forms. Using the base of the homology defined by Ray and Singer in [27] we compute also the Ray-Singer torsion of the spheres, lens spaces and the cone over the spheres. This last one provides the disc as a particular case. For the closed manifolds we obtain the analytic torsion using the Cheeger-Müller Theorem [7, 22] and for the disc using a formula proved by Brüning and Ma in [5]
115

Homogénéisation et Controle Optimal pour des Problèmes de Stokes et pour un Problème de Torsion Elastique

ZOUBAIRI, Hakima 13 December 2001 (has links) (PDF)
Cette thése est consacrée à l'étude du contrôle optimal et de l'homogénéisation de problèmes liés à l'équation de Stokes ainsi qu'au problème de torsion élastique. Pour chaque problème étudié, nous imposons un contrôle à l'équation d'état. Ce contrôle appartient à un ensemble appelé ``ensemble de contrôles admissibles". On se donne une fonction coût qui dépend à la fois de l'état mais aussi du contrôle. Le contrôle optimal (unique) est la fonction dans l'ensemble de contrôles admissibles qui minimise la fonction coût pour tous les contrôles dans cette ensemble. On étudie alors le comportement limite de celui-ci. S'il admet une limite, on la caractérise si possible, comme étant le contrôle optimal associé au problème limite homogénéisé. Dans un premier temps, on étudie un problème de contrôle optimal dans un mélange de deux fluides. Ces deux fluides sont répartis périodiquement l'un par rapport à l'autre dans un domaine bi ou tridimensionnel. L'écoulement des deux fluides obéit aux équations de Stokes. Par la suite, on s'intéresse encore à un mélange de deux fluides visqueux incompressibles séparés par une interface qui oscille rapidement. Ce problème est régit par les équations de Stokes. Ensuite, on étudie le contrôle optimal pour les équations de Stokes dans les domaines perforés. On suppose que les perforations sont de taille plus petite qu'une période donnée. En dernier lieu, on est amené à étudier le contrôle optimal d'un problème de torsion élastique. Dans chacune de ces parties, on caractérise la limite du contrôle optimal comme étant le contrôle optimal du problème limite.
116

Stress Analysis on Adhesive Bonded Joint of Composite Tube due to Torsion

Wang, Wei-Te 07 September 2001 (has links)
The purpose of this thesis is aimed to predict that what kind of adhesive bonded joint of composite tube the can obtain more efficient structure. APC-2 sixteen-layer laminates of AS-4/PEEK were used as adherends, including cross-ply [0/90]4S and quasi-isotropic [0/45/90/-45]2S laminates. And we use two different kinds of adhesive bonded joints, including stepped lap joint and scarf lap joint. On the aspect of numerical analysis, we employ finite element method incorporate with the software of ANSYS 5.5.1 to obtain the distribution of stress on adhesive bonded joint. In this thesis, there are two kinds of geometrical shape on stepped lap joint. The bonded layer height h that is vertical to the axis of the composite tube is 2mm and 5mm. There are also two kinds of the geometrical shape on scarf lap joint. The angle £\ between the bonded layer and the axis of the composite tube is 30¢Xand 45¢X.The boundary condition on one side of the composite tube is assumed to be fixed. The other side of the composite tube is due to torsion. According to the numerical result, the stepped lap joint with h=5mm and quasi-isotropic [0/45/90/-45] occurs minimum von Mises stress, and we predict this kind of joint can sustain the maximum external load and obtain better efficiency. In this thesis, the geometrical shape, size and the direction of laminates of the joint will effect the distribution of stress.
117

Determinig dynamic properties of elastic coupling using experimental data and finite element analysis

Davis, Roosevelt. January 2003 (has links)
Thesis (M.S.)--Mississippi State University. Department of Mechanical Engineering. / Title from title screen. Includes bibliographical references.
118

Techniques of meso-scale measurement of fibre assemblies

Chilo, Marco January 2013 (has links)
The objective of this research project is to investigate novel concepts of determining fibre assembly mechanical properties at woven fabric at meso-scale, viz. yarns and unit-cell. In order to carry out this investigation three instruments were developed and these are presented in subsequent chapters of this thesis. Initially, an instrument was built in order to explore the buckling technique on yarns and fabrics. The data obtained was converted into pure bending output through a proposed non-linear planar elastica model. It was found that the data obtained were in agreement with data obtained from other measuring technique already available in the industry, viz. Pure Bending tester (KES FB2) from the Kawabata Evaluation System. This investigation also found that the buckling technique offers some advantages when compared with the bending tester. Furthermore, the yarn compression method was also explored. A Yarn Compression tester (YCT) was developed in order to carry out this study. This instrument induces transverse compression upon the yarn by means of a probe, which results in a compression versus thickness curve. An, additional feature was introduce on the YCT, such as the use of a digital camera that allows the yarn lateral spreading to be determined as the yarn is compressed. This feature may be used to calculate the Poisson’s ratio, which can be used as an input value for future compression models. Good agreement was found between the proposed yarn compression technique and data obtained from the Kawabata compression tester.Finally, yarn torsional technique was explored by means of developing a Yarn Torsion tester (YTT). It was found that data obtained for this instrumentation were in agreement with a linear model proposed by Postle et al. This investigation may allow future research to continue by means of proposing a torsion mathematical model.
119

An investigation of concrete elements subjected to combined axial compression, bending and torsion.

Lim, Si-Ngiam January 1969 (has links)
No description available.
120

Seismic torsional response of asymmetrical multi-storey frame buildings /

Sarvghad-Moghadam, Abdoreza. January 1998 (has links)
Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (p. 215-222). Also available via World Wide Web.

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