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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.
291

A step towards a unified treatment of continuous and discrete time control problems

Mehrmann, V. 30 October 1998 (has links)
In this paper introduce new approach for unified theory for continuous and discrete time (optimal) control problems based on the generalized Cayley transformation. We also relate the associated discrete and continuous generalized algebraic Riccati equations. We demonstrate the potential of this new approach proving new result for discrete algebraic Riccati equations. But we also discuss where this new approach as well as all other approaches still is non-satisfactory. We explain a discrepancy observed between the discrete and continuous cse and show that this discrepancy is partly due to the consideration of the wrong analogues. We also present an idea for a metatheorem that relates general theorems for discrete and continuous control problems.
292

Numerical solution of generalized Lyapunov equations

Penzl, T. 30 October 1998 (has links)
Two efficient methods for solving generalized Lyapunov equations and their implementations in FORTRAN 77 are presented. The first one is a generalization of the Bartels--Stewart method and the second is an extension of Hammarling's method to generalized Lyapunov equations. Our LAPACK based subroutines are implemented in a quite flexible way. They can handle the transposed equations and provide scaling to avoid overflow in the solution. Moreover, the Bartels--Stewart subroutine offers the optional estimation of the separation and the reciprocal condition number. A brief description of both algorithms is given. The performance of the software is demonstrated by numerical experiments.
293

Zobecněné odhadovací rovnice (GEE) / Generalized estimating equaitons

Sotáková, Martina January 2020 (has links)
In this thesis we are interested in generalized estimating equations (GEE). First, we introduce the term of generalized linear model, on which generalized estimating equations are based. Next we present the methos of pseudo maximum likelyhood and quasi-pseudo maximum likelyhood, from which we move on to the methods of generalized estimating equations. Finally, we perform simulation studies, which demonstrates the theoretical results presented in the thesis. 1
294

The Study of Battery Electric Vehicle DiffusionConsidering  Technology Development Impact : A model based study of Swedish market / En studie om diffusion av batteridrivna elektriska fordon med hänsyn till påverkan av teknisk utveckling : En modellbaserad studie av den svenska marknaden

Xiao, Xiang, Zhang, Wenbin January 2015 (has links)
Battery Electric Vehicle as an environmental friendly transportation alternative has already emerged as well as fade out of the market twice. It has been reintroduced along with the increasing concern about the environment issue. This recent diffusion is surrounded by lots of dynamic changes and uncertainties. However, most current studies focus on political, financial as well as infrastructure factors but neglect factors like the technology especially how people perceived it. Therefore, this study mainly research into how the technology development impact on the diffusion of battery electric vehicle.To achieve this aim, a model based study was conducted targeting Swedish electric vehicle market. In the research, customers are considered to be the target objective because they are the one  who perceive the technology and make decision for adoption directly. In order to know the relationship between them, researches have been conducted through qualitative and quantitative approach. Empirical work including interviews and survey were conducted through tripartite aspect to investigate the customer needs and related technology. The investigation indicates the environmentally friendly performance is the key driving force perceived by the early adopters. Meanwhile, range issue, total cost of ownership and safety & technology reliability are identified as the top three critical concerns that  hold back customer purchasing decision. A modified classic model for the innovation diffusion has been proposed which is used to evaluate the technology’s perception based on historical data. Two BEV- related technologies were chosen as examples to prove and illustrate the relationship between technology development and electric vehicle diffusion.The results showed that the BEV-related technologies, which have potential ability to address critical customer demand, are able to impact on the customer adoption positively through valid perception by customer. Taking technology development and perception into consideration, the diffusion process should be accelerated to some extent. Technologies which can be more easily perceived tend to have more impact in the diffusion process. / Batteridrivna elektriska fordon(BEV) som ett miljövänligt transportalternativ redan har dykt upp, liksom försvunnit från marknaden två gånger. Det har återinförts tillsammans med den ökande oron för miljöfrågan. Denna nya diffusion är omgiven av dynamiska förändringar och osäkerheter. Men de flesta av dagens studier fokuserar på politiska, ekonomiska och infrastrukturella faktorer, men försummar faktorer relaterat till tekniken framför allt hur människor uppfattar det. Därför undersökte denna studie främst hur den tekniska utvecklingen påverkar spridningen av batteridrivna fordon.För att uppnå detta syfte, gjordes en modell baserad kring en studie av den svenska elbilsmarknaden. I forskningen anses kunderna vara målet målgruppen eftersom de är de som uppfattar tekniken och tar beslut om införandet direkt. För att veta förhållandet mellan dem, har kvalitativa och kvantitativa undersökningar genomförts. Empiriskt arbete inklusive intervjuer och undersökningen genomfördes genom tre olika aspekter för att undersöka kundernas behov och relaterad teknik. Undersökningen visar att miljövänlig prestanda är den viktigaste drivkraften som uppfattas av early adopters. Samtidigt har räckviddsproblematiken, totala ägandekostnaden och tillförlitlighet i säkerhet och teknologi identifierats som de tre kritiska problemen som tillbakahåller kunden från ett köpbeslut. En modifierad klassisk modell för innovationsspridning har föreslagits som används för att utvärdera teknikens uppfattning baserad på historiska data. Två BEV-relaterade teknologier valdes som exempel för att bevisa och illustrera förhållandet mellan teknikutveckling och elbilsdiffusion.Resultaten visade att BEV-relaterad teknologi, som har potential förmåga att ta itu med den kritiska efterfrågan från kunderna, kan påverka kundacceptans positivt genom giltig uppfattning av kunden. Om teknikutveckling och uppfattning beaktas, bör diffusionsprocessen påskyndas i viss utsträckning. Teknik som lättare kan uppfattas tenderar att ha mer genomslag i diffusionsprocessen.
295

Parametric stability analyses for fluid-loaded thin membranes

Zhou, Yang January 2015 (has links)
Membrane structures are commonly used in many elds. The studies of thesestructures are of increasing interest. The two projects focus on the evaluations ofequilibrium states for uid-pressurized membranes under dierent loading conditions,and the corresponding instability behavior.The rst part of the current work discusses the instability behavior of a thin,planar, circular and initially horizontal membrane subjected to downwards or upwards uid pressure. The membrane structures exhibit large deformations under uid pressure. Various instability behaviors have been observed for dierent loadingparameters. Limit and bifurcation points have been detected for dierent loadingconditions. Dierent loading parameters have been used to interpret the instabilitybehavior. The eects on instability of parameters, the initial states of the membrane,and the chosen mesh have been discussed.The second part of the current work discusses instability behavior of a thin,spherical and closed membrane containing gas and uid placed on a horizontal rigidand non-friction plane. A multi-parametric loading has been described. By addingthe practically relevant controlling equations, the complex equilibrium paths werefollowed using the generalized path following algorithm, and the stability conclusionswere made dierently, according to the considered load parameters and theconstraints. A generalized eigenvalue analysis was used to evaluate the stabilitybehavior including the constraint eects. Fold line evaluations were performed toanalyze the parametric dependence of the instability behavior. A solution surfaceapproach was used to visualize the mechanical response under this multi-parametricsetting. / <p>QC 20151029</p>
296

Vztak s rodičmi ako faktor utvárania dovery: Analýza medzigeneračného prenosu generalizovanej dovery na prípade Husákových deti / Parent-child relationship as a factor in the genesis of trust: Analysis of the intergenerational transmission of generalized trust on the case Husak's children

Fedorková, Marta January 2013 (has links)
Bibliografický záznam FEDORKOVÁ, Marta. Parent-child relationship as a factor in the genesis of trust: An analysis of intergenerational transmission of generalized trust on the case of Husák's children. Praha, 2013. 78 s. Diplomová práce (Mgr.) Univerzita Karlova, Fakulta sociálních věd, Institut sociologických studií. Vedoucí diplomové práce Mgr. Jiří Remr, Ph.D., MBA Abstract This thesis extends the developing research on the sources of generalized trust by analyzing how the character of the parent-child relationship influences its formation and transfer - an aspect of trust genesis not previously addressed in the Czech context. Using data from a unique survey Distinctions and Values 2008, we explore the heterogeneity in the parental influence on trust on the case of Czech 30- year-olds and their parents. We first delimit the concept of generalized trust, presenting its most relevant current conceptualizations as well as a review of the current state of knowledge on its origins and transmission. Using Bengston's model of intergenerational transmission of values as our framework, we then in the second part of the paper look into the degree of similarity between parents and their offspring in terms of their willingness to trust others, and use logistic ordinal regression to examine how it is influenced by a...
297

Contrôle d’erreur pour et par les modèles réduits PGD / Error control for and with PGD reduced models

Allier, Pierre-Eric 21 November 2017 (has links)
De nombreux problèmes de mécanique des structures nécessitent la résolution de plusieurs problèmes numériques semblables. Une approche itérative de type réduction de modèle, la Proper Generalized Decomposition (PGD), permet de déterminer l’ensemble des solutions en une fois, par l’introduction de paramètres supplémentaires. Cependant, un frein majeur à son utilisation dans le monde industriel est l’absence d’estimateur d’erreur robuste permettant de mesurer la qualité des solutions obtenues. L’approche retenue s’appuie sur le concept d’erreur en relation de comportement. Cette méthode consiste à construire des champs admissibles, assurant ainsi l’aspect conservatif et garanti de l’estimation de l’erreur en réutilisant le maximum d’outils employés dans le cadre éléments finis. La possibilité de quantifier l’importance des différentes sources d’erreur (réduction et discrétisation) permet de plus de piloter les principales stratégies de résolution PGD. Deux stratégies ont été proposées dans ces travaux. La première s’est principalement limitée à post-traiter une solution PGD pour construire une estimation de l’erreur commise, de façon non intrusive pour les codes PGD existants. La seconde consiste en une nouvelle stratégie PGD fournissant une approximation améliorée couplée à une estimation de l’erreur commise. Les diverses études comparatives sont menées dans le cadre des problèmes linéaires thermiques et en élasticité. Ces travaux ont également permis d’optimiser les méthodes de construction de champs admissibles en substituant la résolution de nombreux problèmes semblables par une solution PGD, exploitée comme un abaque. / Many structural mechanics problems require the resolution of several similar numerical problems. An iterative model reduction approach, the Proper Generalized Decomposition (PGD), enables the control of the main solutions at once, by the introduction of additional parameters. However, a major drawback to its use in the industrial world is the absence of a robust error estimator to measure the quality of the solutions obtained.The approach used is based on the concept of constitutive relation error. This method consists in constructing admissible fields, thus ensuring the conservative and guaranteed aspect of the estimation of the error by reusing the maximum number of tools used in the finite elements framework. The ability to quantify the importance of the different sources of error (reduction and discretization) allows to control the main strategies of PGD resolution.Two strategies have been proposed in this work. The first was limited to post-processing a PGD solution to construct an estimate of the error committed, in a non-intrusively way for existing PGD codes. The second consists of a new PGD strategy providing an improved approximation associated with an estimate of the error committed. The various comparative studies are carried out in the context of linear thermal and elasticity problems.This work also allowed us to optimize the admissible fields construction methods by substituting the resolution of many similar problems by a PGD solution, exploited as a virtual chart.
298

Improved Stereo Vision Methods for FPGA-Based Computing Platforms

Fife, Wade S. 28 November 2011 (has links) (PDF)
Stereo vision is a very useful, yet challenging technology for a wide variety of applications. One of the greatest challenges is meeting the computational demands of stereo vision applications that require real-time performance. The FPGA (Field Programmable Gate Array) is a readily-available technology that allows many stereo vision methods to be implemented while meeting the strict real-time performance requirements of some applications. Some of the best results have been obtained using non-parametric stereo correlation methods, such as the rank and census transform. Yet relatively little work has been done to study these methods or to propose new algorithms based on the same principles for improved stereo correlation accuracy or reduced resource requirements. This dissertation describes the sparse census and sparse rank transforms, which significantly reduce the cost of implementation while maintaining and in some case improving correlation accuracy. This dissertation also proposes the generalized census and generalized rank transforms, which opens up a new class of stereo vision transforms and allows the stereo system to be even more optimized, often reducing the hardware resource requirements. The proposed stereo methods are analyzed, providing both quantitative and qualitative results for comparison to existing algorithms. These results show that the computational complexity of local stereo methods can be significantly reduced while maintaining very good correlation accuracy. A hardware architecture for the implementation of the proposed algorithms is also described and the actual resource requirements for the algorithms are presented. These results confirm that dramatic reductions in hardware resource requirements can be achieved while maintaining high stereo correlation accuracy. This work proposes the multi-bit census, which provides improved pixel discrimination as compared to the census, and leads to improved correlation accuracy with some stereo configurations. A rotation-invariant census transform is also proposed and can be used in applications where image rotation is possible.
299

[en] MICROPARAMETERS CALIBRATION PROCESS IN DEM VIA GENERALIZED SIMULATED ANNEALING / [pt] PROCESSO DE CALIBRAÇÃO DOS MICROPARÂMETROS EM MÉTODO DE ELEMENTOS DISCRETOS VIA GENERALIZED SIMULATED ANNEALING

FELIPE TAJA COSTA PINTO 16 August 2021 (has links)
[pt] O Método dos Elementos Discretos (Discrete Element Method - DEM) é uma técnica numérico computacional capaz de simular o comportamento macroscópico de um material via solução das equações do movimento de seus constituintes. Para uma correta predição deste comportamento são informados, como dados de entrada, as características mecânicas dos elementos: os chamados microparâmetros. Contudo, não existe uma receita que determine estes microparâmetros baseados somente nas respostas macroscópicas do material simulado, necessitando de um passo adicional conhecido como Calibração. Tentativa e erro, um método ineficiente por conta de seu fator de escala desfavorável, é o mais comumente utilizado nesta etapa. Este trabalho propõe uma nova abordagem utilizando-se do método de otimização global Generalized Simulated Annealing, minimizando-se a área quadrática normalizada entre as curvas experimentais e calculadas de tensão-deformação axial e deformações volumétrica-axial simultaneamente. Foram efetuadas comparações via ensaio triaxial para dados sintéticos e reais cujos resultados demonstram o aproveitamento e aplicabilidade da técnica proposta. / [en] The Discrete Element Method (DEM) is a numerical computational technique that simulates the macroscopic material behaviour by solving the equations of motion of its constituents. For a correct prediction of this behaviour, are set as input data the mechanical characteristics of the elements, the so-called microparameters. However, there is no recipe for determining these microparameters based solely on the macroscopic responses of the simulated material. It is required an additional step known as Calibration. The method widely used in this calibration is trial and error, although is an inefficient method due its unfavorable scale factor. This work proposes a new approach using the Generalized Simulated Annealing global optimization method, minimizing the normalized quadratic area between the experimental and calculated curves of the axial stress-strain and volumetric-axial deformations curves simultaneously. Comparison is done using triaxial tests for both synthetic and real data whose results demonstrate the usefulness and applicability of the proposed approach.
300

Corrected LM goodness-of-fit tests with applicaton to stock returns

Percy, Edward Richard, Jr. 05 January 2006 (has links)
No description available.

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