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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.
151

Stabilization Schemes for Convection Dominated Scalar Problems with Different Time Discretizations in Time dependent Domains

Srivastava, Shweta January 2017 (has links) (PDF)
Problems governed by partial differential equations (PDEs) in deformable domains, t Rd; d = 2; 3; are of fundamental importance in science and engineering. They are of particular relevance in the design of many engineering systems e.g., aircrafts and bridges as well as to the analysis of several biological phenomena e.g., blood ow in arteries. However, developing numerical scheme for such problems is still very challenging even when the deformation of the boundary of domain is prescribed a priori. Possibility of excessive mesh distortion is one of the major challenge when solving such problems with numerical methods using boundary tted meshes. The arbitrary Lagrangian- Eulerian (ALE) approach is a way to overcome this difficulty. Numerical simulations of convection-dominated problems have for long been the subject to many researchers. Galerkin formulations, which yield the best approximations for differential equations with high diffusivity, tend to induce spurious oscillations in the numerical solution of convection dominated equations. Though such spurious oscillations can be avoided by adaptive meshing, which is computationally very expensive on ne grids. Alternatively, stabilization methods can be used to suppress the spurious oscillations. In this work, the considered equation is designed within the framework of ALE formulation. In the first part, Streamline Upwind Petrov-Galerkin (SUPG) finite element method with conservative ALE formulation is proposed. Further, the first order backward Euler and the second order Crank-Nicolson methods are used for the temporal discretization. It is shown that the stability of the semi-discrete (continuous in time) ALE-SUPG equation is independent of the mesh velocity, whereas the stability of the fully discrete problem is unconditionally stable for implicit Euler method and is only conditionally stable for Crank-Nicolson time discretization. Numerical results are presented to support the stability estimates and to show the influence of the SUPG stabilization parameter in a time-dependent domain. In the second part of this work, SUPG stabilization method with non-conservative ALE formulation is proposed. The implicit Euler, Crank-Nicolson and backward difference methods are used for the temporal discretization. At the discrete level in time, the ALE map influences the stability of the corresponding discrete scheme with different time discretizations, and it leads to schemes where conservative and non-conservative formulations are no longer equivalent. The stability of the fully discrete scheme, irrespective of the temporal discretization, is only conditionally stable. It is observed from numerical results that the Crank-Nicolson scheme induces high oscillations in the numerical solution compare to the implicit Euler and the backward difference time discretiza-tions. Moreover, the backward difference scheme is more sensitive to the stabilization parameter k than the other time discretizations. Further, the difference between the solutions obtained with the conservative and non-conservative ALE forms is significant when the deformation of domain is large, whereas it is negligible in domains with small deformation. Finally, the local projection stabilization (LPS) and the higher order dG time stepping scheme are studied for convection dominated problems. The analysis is based on the quadrature formula for approximating the integrals in time. We considered the exact integration in time, which is impractical to implement and the Radau quadrature in time, which can be used in practice. The stability and error estimates are shown for the mathematical basis of considered numerical scheme with both time integration methods. The numerical analysis reveals that the proposed stabilized scheme with exact integration in time is unconditionally stable, whereas Radau quadrature in time is conditionally stable with time-step restriction depending on the ALE map. The theoretical estimates are illustrated with appropriate numerical examples with distinct features. The second order dG(1) time discretization is unconditionally stable while Crank-Nicolson gives the conditional stable estimates only. The convergence order for dG(1) is two which supports the error estimate.
152

Le pouvoir discrétionnaire du juge et l'inexécution du contrat : étude de droit comparé franco-allemande / Discretionary power of the judge and breach of contract : a comparative study of french and german law

Signat, Carine 14 November 2014 (has links)
La question de la mesure du pouvoir du juge s’impose lorsqu’on souhaite comparer l’étendue des pouvoirs du juge dans différents ordres juridiques donnés. Or force est de constater que les pouvoirs du juge sont appréhendés sous diverses notions dans les systèmes juridiques nationaux : il est fait tour à tour référence au pouvoir souverain d’appréciation du juge du fond, au pouvoir facultatif du juge, à son pouvoir modérateur, discrétionnaire, arbitraire. Toute la difficulté de la comparaison réside dans l’absence d’un instrument de mesure uniforme. A l’échelle supranationale, le terme anglais « Judicial discretion » constitue souvent le point de départ de discussions et d’analyses comparatives sur les pouvoirs du juge. Cette notion à forte coloration doctrinale sert de critère de mesure de l’ampleur des pouvoirs du juge dans les systèmes juridiques respectifs. On entend par pouvoir discrétionnaire le pouvoir donné au juge de choisir entre deux ou plusieurs décisions également conformes à la légalité. Le critère du libre choix est au cœur de la notion du pouvoir discrétionnaire du juge. Le pouvoir discrétionnaire constitue ainsi la forme la plus libre du pouvoir exercé par le juge. Bien qu’elle fasse office de dénominateur commun, la notion de pouvoir discrétionnaire est diversement entendue en droits français et allemand. Il en va ainsi en particulier à propos des notions-cadre et standards : ces derniers confèrent-ils au juge un pouvoir discrétionnaire ? Les réponses divergent d’un système à l’autre, ce qui a un impact sur l’image qu’on se fait des pouvoirs du juge. Une fois ces malentendus dissipés, reste à déterminer la part faite à ce pouvoir dans les suites de l’inexécution du contrat : exécution forcée en nature, délai d’exécution et révision, résolution. / How to measure a judge’s power? This question is necessary, when it comes to comparing the extent of the powers of a judge in various given jurisdictions. It has tobe noted, that the powers of a judge are gathered under diverse notions in national legal systems: successively, references are made to the sovereign judicial authority of the judge, the unfettered discretion of the lower courts, the authority to modify the legal situation, the discretionary power, the arbitrary power. The challenge in the comparison lies in the absence of a uniform measuring tool. On a supranational level,the English term“Judicial discretion”is very frequently the starting point for discussions and comparative analyses regarding the judge’s power. This notion serves as criteria to measure the extent of the judge’s powers in the respective legal systems. Discretionary power means the power given to the judge to choose between different decisions that are all conformable to law. The criterion of freedom of choice is in the center of the judge’s discretionary power. The discretionary power is the most powerful authority of the judge. It is common sense that the judge has a discretionarypower but the meaning of this term is differently interpretated by the national law,especially by the German and French law systems. This applies especially to the standards provisions or“open-textured”provisions : do they grant the judge a discretionary power? The answers vary from one system to the other, which has an impact on the image one has on the judge’s powers. Once these misunderstandings are dispelled, it remains to determine the proportion this power has in the consequences of the non-performance of contract: specific performance, delay inexecution, revision and termination.
153

Elektronické filtrační obvody s obecnými kmitočtovými charakteristikami / Electronic Filtering Circuits with Arbitrary Frequency Characteristics

Klubus, Jan January 2020 (has links)
Master’s thesis deals with the issue of electronic filtering circuits with arbitrary frequency characteristics. First part of the thesis describes theoretical basis. Second part explores the possibilities of design procedures for filters with arbitrary frequency characteristics. Design procedures are demonstrated on examples accordingly to the presented methods, including their circuit implementation and computer simulation to verify the correctness of theoretical assumptions. Thesis also explores the possibilities of tuning circuit structures and electronic setting for characteristics using controllable active elements.
154

Design optimization of heterogeneous microstructured materials

Emami, Anahita January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Our ability to engineer materials is limited by our capacity to tailor the material’s microstructure morphology and predict resulting properties. The insufficient knowledge on microstructure-property relationship is due to complexity and randomness in all materials at different scales. The objective of this research is to establish a design optimization methodology for microstructured materials. The material design problem is stated as finding the optimum microstructure to maximize the desired performance satisfying material processing constrains. This problem has been solved in this thesis by means of numerical techniques through four main steps: microstructure characterization, model reconstruction, property evaluation, and optimization. Two methods of microstructure characterizations have been investigated along with the advantages and disadvantages of each method. The first microstructure characterization method is a statistical method which utilizes correlation functions to extract the microstructural information. Algorithms for calculating these correlations functions have been developed and optimized based on their computational cost using MATLAB software. The second microstructure characterization method is physical characterization which works based on evaluation of physical features in microstructured domain. These features have been measured by means of MATLAB codes. Three model reconstruction techniques are proposed based on these characterization methods and employed to generate material models for further evaluation. The first reconstructing algorithm uses statistical functions to reconstruct the statistical equivalent model through simulating annealing optimization method. The second algorithm uses cellular automaton concepts to simulate the grain growth utilizing physical descriptors, and the third one generates elliptical inclusions in a material matrix using physical characteristic of microstructure. The finite element method is used to analysis the mechanical behavior of material models. Several material samples with different microstructural characteristics have been generated to model the micro-scale design domain of AZ31 magnesium alloy and magnesium matrix composite with silicon carbide fibers. Then, surrogate models have been created based on these samples to approximate the entire design domain and demonstrate the sensitivity of the desired mechanical property to two independent microstructural features. Finally, the optimum microstructure characteristics of material samples for fracture strength maximization have been obtained.
155

Reconfigurable Reflective Arrayed Waveguide Grating on Silicon Nitride

Fernández Vicente, Juan 29 April 2021 (has links)
[ES] La presente tesis se ha centrado en el modelado, diseño y demonstración experimental por primera vez del dispositivo Reconfigurable Reflective Arrayed Waveguide Grating (R-RAWG). Para la consecución de este dispositivo que tiene posibilidades de uso en la espectrometría, una plataforma de nitruro de silicio llamada CNM-VLC se ha usado, ya que este material permite operar en un gran ancho de banda. Esta plataforma posee ciertas limitaciones y los elementos necesarios para el funcionamiento de este dispositivo tenían un performance bajo. Por ello, se ha desarrollado y validado una metodología que ha permitido obtener mejores divisores. Además, se ha diseñado un inverted taper que ha mejorado considerablemente el acoplo de luz al chip. Esto ha sido gracias a un exhaustivo análisis de opciones existentes en la literatura que también ha permitido escoger la mejor opción para realizar un espejo reconfigurable en la plataforma sin cambiar ni añadir ningún proceso de fabricación. Se han demostrado espejos reconfigurables gracias a utilizar divisores ópticos realimentados y también se ha desarrollado códigos que predicen el comportamiento del dispositivo experimentalmente. Con todo el trabajo realizado, se ha diseñado un R-RAWG para que pudiera operar en un gran ancho de banda y que los actuadores de fase no tuvieran peligro de estropearse. También se ha desarrollado un código para el modelado del R-RAWG que permite imitar la fabricación de estos dispositivos y que, gracias a esto, se ha desarrollado un método o algoritmo llamado DPASTOR, que usa algoritmos usados en machine learning, para optimizar la respuesta con tan sólo la potencia óptica de salida. Finalmente, se ha diseñado una PCB para poder conectar eléctricamente el chip fotónico y se ha desarrollado un método de medida que ha permitido tener una respuesta estable consiguiendo demostrar multitud de respuestas de filtros ópticos con el mismo dispositivo. / [CAT] La present tesi s'ha centrat en el modelatge, disseny i demonstració experimental per primera vegada del dispositiu Reconfigurable Reflective Arrayed Waveguide Grating (R-RAWG). Per a la consecució d'aquest dispositiu que té possibilitats d'ús en l'espectrometria, una plataforma de nitrur de silici anomenada CNM-VLC s'ha usat ja que aquest material permet operar en una gran amplada de banda. Aquesta plataforma posseeix certes limitacions i els elements necessaris per al funcionament d'aquest dispositiu tenien un performance baix. Per això, s'ha desenvolupat i validat una metodologia que ha permés obtindre millors divisors i també, gràcies als processos de fabricació, s'ha dissenyat un acoplador que ha millorat considerablement l'acoble de llum al xip. Això ha sigut gràcies a un exhaustiu analisis d'opcions existents en la literatura que també ha permés triar la millor opció per a realitzar un espill reconfigurable en la plataforma sense canviar ni afegir cap procés de fabricació. S'han demonstrat espills reconfigurables gràcies a utilitzar divisors realimentats i també s'ha desenvolupat codis que prediuen el comportament del dispostiu experimentalment. Amb tot el treball realitzat, s'ha dissenyat un R-RAWG fent ús de determinades consideracions perquè poguera operar en una gran amplada de banda i que els actuadors de fase no tingueren perill de desbaratar-se. També s'ha desenvolupat un codi per al modelatge del R-RAWG que permet imitar la fabricació d'aquests dispositius i que, gràcies a això, s'ha desenvolupat un mètode o algorisme anomenat DPASTOR, que usa algorismes usats en machine learning, per a optimitzar la resposta amb tan sols la potència òptica d'eixida. Finalment, s'ha dissenyat una PCB per a poder connectar elèctricament el xip fotònic i s'ha desenvolupat un mètode de mesura que ha permés tindre una resposta estable aconseguint demostrar multitud de respostes de filtres òptics amb el mateix dispositiu. / [EN] This thesis is focused on the modelling, design and experimental demonstration for the first time of Reconfigurable Reflective Arrayed Waveguide Grating (R-RAWG) device. In order to build this device, that can be employed in spectrometry, a silicon nitride platform termed CNM-VLC has been chosen since this material allows to operate in broad range of wavelengths. This platform has the necessary elements, but some limitations because the operation of this device had a low performance. Therefore, a methodology has been developed and validated, which has allowed to obtain better splitters. Also an inverted taper has been designed, which has considerably improved the coupling of light to the chip. This has been possible thanks to an exhaustive analysis of existing options in the literature, that has allowed choosing the best option to make a reconfigurable mirror on the platform without changing or adding new manufacturing steps. Reconfigurable mirrors have been demonstrated by using feedback splitters. Furthermore, codes have been developed to predict the behaviour of the actual device. With all the work done, a R-RAWG has been designed by using certain considerations so that it can operate over a broad wavelength range and the phase actuators are not in danger of being damaged. A code has also been developed for the modelling of the R-RAWG, which allows manufacturing imperfections to be considered, thanks to this, a method or algorithm called DPASTOR has been developed. DPASTOR resembles machine learning to optimise the response by just using the optical output power. Finally, a PCB and an assembly with the chip interconnected to it have been made and designed. Moreover, a measurement method has been developed, which has made it possible to have a stable response and to demonstrate a multitude of optical filter responses with the same device. / Fernández Vicente, J. (2021). Reconfigurable Reflective Arrayed Waveguide Grating on Silicon Nitride [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/165783
156

A high order Discontinuous Galerkin - Fourier incompressible 3D Navier-Stokes solver with rotating sliding meshes for simulating cross-flow turbines

Ferrer, Esteban January 2012 (has links)
This thesis details the development, verification and validation of an unsteady unstructured high order (≥ 3) h/p Discontinuous Galerkin - Fourier solver for the incompressible Navier-Stokes equations on static and rotating meshes in two and three dimensions. This general purpose solver is used to provide insight into cross-flow (wind or tidal) turbine physical phenomena. Simulation of this type of turbine for renewable energy generation needs to account for the rotational motion of the blades with respect to the fixed environment. This rotational motion implies azimuthal changes in blade aero/hydro-dynamics that result in complex flow phenomena such as stalled flows, vortex shedding and blade-vortex interactions. Simulation of these flow features necessitates the use of a high order code exhibiting low numerical errors. This thesis presents the development of such a high order solver, which has been conceived and implemented from scratch by the author during his doctoral work. To account for the relative mesh motion, the incompressible Navier-Stokes equations are written in arbitrary Lagrangian-Eulerian form and a non-conformal Discontinuous Galerkin (DG) formulation (i.e. Symmetric Interior Penalty Galerkin) is used for spatial discretisation. The DG method, together with a novel sliding mesh technique, allows direct linking of rotating and static meshes through the numerical fluxes. This technique shows spectral accuracy and no degradation of temporal convergence rates if rotational motion is applied to a region of the mesh. In addition, analytical mappings are introduced to account for curved external boundaries representing circular shapes and NACA foils. To simulate 3D flows, the 2D DG solver is parallelised and extended using Fourier series. This extension allows for laminar and turbulent regimes to be simulated through Direct Numerical Simulation and Large Eddy Simulation (LES) type approaches. Two LES methodologies are proposed. Various 2D and 3D cases are presented for laminar and turbulent regimes. Among others, solutions for: Stokes flows, the Taylor vortex problem, flows around square and circular cylinders, flows around static and rotating NACA foils and flows through rotating cross-flow turbines, are presented.
157

Fundamentos y límites de la analogía in bonam partem en el derecho penal

Montiel Fernández, Juan Pablo 20 September 2008 (has links)
Una adecuada interpretación del principio de legalidad ofrece buenas razones para admitir la analogía in bonam partem en el Derecho penal aunque de un modo limitado. Incluso cuando el juez mediante ésta excluye o limita el ejercicio del ius puniendi, el aplicador del Derecho penal debe seguir apegado a la ley. De este modo, la analogía in bonam partem debe ser vista como un mecanismo excepcional de integración del Derecho penal frente a inconsistencias axiológicas no previstas ni deseadas por el legislador. Estas excepcionales facultades creadoras reconocidas al juez tienen lugar frente a concretas instituciones jurídico-penales y dentro de un determinado marco argumentativo. En este sentido, la analogía in bonam partem es un medio para crear supralegalmente causas de justificación, causas de exculpación y atenuantes, mientras que no para crear excusas absolutorias. Igualmente, el juez puede crear Derecho solamente a partir de la analogía legis o la analogía institutionis, sin resultar posible acudir a la analogía iuris. / An adequate interpretation of the legality principle offers sound reasons to accept analogy in bonam partem in Criminal Law, though only in a limited way. Even when the judge excludes or limits the ius puniendi through the use of analogy, she should still be strictly subjected to the norm. Therefore the analogy in bonam partem must be seen as an exceptional mechanism of Criminal Law's Integration in the presence of axiological inconsistencies that the Parliament didn't foresee and didn't want. These exceptional law-making powers awarded to the judge refer to specific Criminal law institutions and in a specific argumentative framework. In this sense, analogy in bonam partem is an instrument to supra-legally create justifications, excuses, and mitigating circumstances, but not other types of punishment excluding institutions. In the same manner, the judge can create new Criminal Law only through legis Analogy and institutionis Analogy but not through iuris Analogy.
158

Reading Population Transfer in International Human Rights Law, International Humanitarian Law and International Criminal Law through the Principle of Humanity

Mac Allister, Karine 01 1900 (has links)
Le transfert de population est la cause et la conséquence de plusieurs conflits armés. Il comprend le déplacement arbitraire de la population, le transfert de colons ainsi que le confinement des civiles en temps de guerre. Le transfert de population est un crime en droit international des droits de l’homme, en droit international humanitaire et en droit pénal international. Néanmoins, il est encore considéré comme une solution aux problèmes de minorités et aux conflits ‘ethniques’. Cette thèse étudie comment le crime de transfert de population est défini, interprété et appliqué en droit international et par les tribunaux régionaux et internationaux et la communauté internationale selon l’État de droit. / Population transfer is a cause and consequence of armed conflict. It entails the arbitrary displacement of the population, the implantation of settlers and unlawful confinement. It is a violation of international human rights law and international humanitarian law and a crime in international criminal law. Yet, it is still considered a solution to minority and ‘ethnic’ problems. Using the rule of law as theoretical framework, this thesis assesses how the crime of population transfer is defined, interpreted and applied under international law and by regional and international courts as well as by the international community.
159

Assessing the compatibility of the right to a fair trial under Sudanese law with international human rights law

Abdalla, Amir Kamaleldin Ahmed 11 1900 (has links)
This thesis investigates the compatibility of a crucial aspect of Sudanese criminal justice, namely, the compatibility of the right to a fair trial with two main sources of this right: international human rights law and Shari’a law. The right to a fair trial is a cornerstone for any society and serves to observe the rule of law and other rights of citizens. The study illustrates that the right to a fair trial could play a significant role in the protection of human rights in Sudan. The main aim of this study is to establish ways in which the right to a fair trial can be strengthened in Sudan. The thesis has examined the work emanating from the international level by reviewing decisions, providing general comments and analysing other jurisprudence emanating from bodies such as the African Commission on Human and Peoples’ Rights and the Human Rights Committee. The decisions, general comments and other jurisprudence from these bodies are juxtaposed against Sudan’s laws to establish the extent to which the right to a fair trial is upheld at the domestic level in Sudan. The study critically examines the sources of the right to a fair trial in Sudan. The main sources of right to a fair trial in Sudan are the Constitution, the Criminal Procedure Act, the Penal Code, Shari’a law and international human rights law. It seeks to answer the question whether Sudanese fair trial rights are compatible with international standards. The study establishes that one of the sources of law that govern the right to a fair trial in Sudan is Shari’a law. The main principle in Islam is that nothing is unlawful, unless it is expressly forbidden by law. However, the Shari’a law in Sudan has not been properly implemented as is illustrated through the rigid and traditional implementation of some of its provisions. The selective and rigid implementation of provisions of Shari’a law has resulted in a conflict with the accepted international standards of fair trial rights. What the study establishes is that a more progressive interpretation of Shari’a law can potentially solve the contradictions with international human rights law that currently exist. The study identifies a number of factors that have affected the development of the right to a fair trial in Sudan. Among these factors are the lack of political will, poverty, the lack of awareness about rights, laws that are contrary to the right to a fair trial, laws that inadequately protect victims and witnesses, impunity, corruption, the lack of resources both human and financial, abuse of power, existence of military and special courts, institutional constraints, discrimination against women, and the refusal or resistance of the executive branch of government to implement decisions of the courts. This study concludes that some pre-trial, trial and post-trial rights and standards in Sudan are not in conformity with international and regional standards. The study concludes by making a number of recommendations aimed at institutional and legal reform. / Dissertation (LLD)--University of Pretoria, 2014. / Centre for Human Rights / LLD / Unrestricted
160

La condition juridique des personnes privées de liberté du fait d'une décision administrative / The legal status of persons deprived of liberty by an administrative decision

Boutouila, Nawal 09 July 2014 (has links)
En empruntant une démarche prospective, l’objectif de cette contribution est de mettre en lumière l’existence d’une évolution de la condition juridique des personnes privées de liberté du fait d’une décision administrative. Si pendant longtemps l’obligation de préserver l’ordre public a été présentée comme conférant de nombreuses prérogatives à l’administration, elle doit désormais être décrite comme une mission de service public devant s’accomplir conformément à un modèle de comportement, sans toutefois que l’on puisse aujourd’hui évoquer l’existence de véritables sujétions à la charge de l’administration. Si cette évolution a été rendue possible, c’est en grande partie grâce à de «nouveaux contre-pouvoirs» qui ont contribué au renforcement de leur protection en participant plus ou moins directement à l’identification des obligations que toute administration qui prend en charge une personne privée de liberté devrait respecter et en concourant à leur défense. / By taking a prospective approach, the main of this work is to highlight the existence of an evolution of the legal status of persons deprived of their liberty for an administrative decision. Though the obligation to preserve public order has long been introduced as granting the administration many prerogatives, it must from now on to be equally described as a public-service mission that should be accomplished in accordance with a particular behavior model, without however, always mentioning the presence of actual constraints at the expense of the administration because of the numerous shortcomings currently affecting the protection system. Presumably, if this improvement has been made possible, it is in mainly due to “this new opposing-force concept” that has contributed to strengthening theirs protection especially by participating in the identification of the obligations that should be respected by all administrations which have to take care of a person deprived of liberty.

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