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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.
171

Numerical Method For Conform Reflection

Kushnarov, Andriy 01 January 2010 (has links) (PDF)
Conformal map has application in a lot of areas of science, e.g., fluid flow, heat conduction, solidification, electromagnetic, etc. Especially conformal map applied to elasticity theory can provide most simple and useful solution. But finding of conformal map for custom domain is not trivial problem. We used a numerical method for building a conformal map to solve torsion problem. In addition it was considered an infinite system method to solve the same problem. Results are compared.
172

Transversality Conditions for Infinite Horizon Optimality:Higher Order Differential Problems

OKUMURA, Ryuhei, 奥村, 隆平, CAI, Dapeng, 蔡, 大鵬, NITTA, Takashi Gyoshin 04 March 2009 (has links)
No description available.
173

Robust H-infinite Design for Uncertain Discrete Descriptor Systems with Pole-Clustering in a Disk¡GA Strict LMI Approach

Hu, Chia-Ho 10 July 2002 (has links)
This thesis presents strict LMI conditions for the bounded real lemma of discrete descriptor systems. Compared with existing nonstrict LMI conditions, the proposed new conditions are more tractable and reliable in numerical computations, in the sense that they can be tested easily by using the LMI Control Toolbox of Matlab. Based on the strict LMI conditions, the state feedback design for H-infinite control problem is also addressed. A sufficient LMI condition is derived so that the constructed feedback gain matrix from its solution will meet the design criteria of the closed-loop systems. Furthermore, we can probe into the problems of robust H-infinite control and pole-clustering in a disk for uncertain discrete descriptor systems subject to time-invariant norm-bounded uncertainty and convex polytopic uncertainty in the state matrix, respectively. Some sufficient LMI conditions are derived for analysis and design of these problems as well. Numerical examples are included to illustrate the results.
174

Robust Control of Wafer Temperature Uniformity in Rapid Thermal Chemical Vapor Deposition Systems

Chang, Jui-Sheng 23 July 2003 (has links)
The Rapid Thermal Chemical Vapor Deposition (RTCVD) system is an emerging and promising technology in semiconductor manufacturing which possess advantages of rapidly increasing wafer temperature and reducing the thermal budget over traditional batch processing. In recent years, the growth of thin films in the manufacture of semiconductor devices has been widely employed in the industry. Because the influences of processing variables on RTCVD systems may lead to spatial wafer temperature non-uniformity, the precise control of wafer temperature is an important issue up to the present. In this paper the complementary sensitivity function shaping based on H-infinite control theory is applied to design robust controllers for the single-input/single-output (SISO) model of the RTCVD system, the multi-input/multi-output (MIMO) model of the RTCVD system, and the MIMO model with multiplicative uncertainties. Through control the power of the tungsten-halogen lamps, it can achieve the temperature tracking with good uniformity. Finally, the computer simulation results are obviously that the performance of the proposed controllers is satisfactory.
175

Children's mathematical understandings of tessellations : a cognitive and aesthetic synthesis

Eberle, Robert Scott 02 April 2012 (has links)
Tessellations have a rich mathematical structure and are especially appropriate as a context for teaching geometry in the middle grades. Few studies have researched how children conceptualize and learn tessellations in spite of their international use in educational contexts. This exploratory study looks at how fourth grade students conceptualize tessellations before instruction. The analysis is done from a Piagetian, cognitive viewpoint and from an aesthetic viewpoint. It is argued that the aesthetic viewpoint is crucial and foundational to children's mathematical understanding, just as it is for mathematicians. A series of clinical interviews was conducted with six fourth grade children. The results identified common themes of children's understanding, strategies, reasoning, and aesthetic criteria for tessellations. Children's ontology varied between object and process conceptions of tessellations. Children struggled especially with the infinite space of mathematical tessellations. Children's aesthetics, including symmetry, influenced their choices in creating tessellations and are shown to have played a cognitive role in children's mathematical exploration of tessellation structures. Mathematics influences students' aesthetic appreciation of tessellations and, more importantly, aesthetics drives the study of the mathematical structure of tessellations. Children's aesthetic criteria were the same as mathematicians', but with much different emphases. Other results are discussed, including the mathematical content elicited by the tasks, the influence of the tools used to create tessellations, the children's epistemology of their tessellations, and the role symmetry played in giving children confidence. Recommendations for future research and possible implications for curriculum and instruction are noted. / text
176

That thing you do

Albala Cardemil, David 17 June 2011 (has links)
This report outlines the process of creating and producing the documentary film “That Thing You Do” based on the TV series “1+1=Infinito” (1+1=Infinite). The series and the film provide a better understanding of the concept of Corporate Social Responsibility (CSR) and shows how people can incorporate CSR into their daily lives. The film production was financed by “PROhumana Foundation” (Chile) and shows how three Chilean people: Rodrigo Alonso, entrepreneur, Catalina Valdés, chef, and Javier del Río, architect, are trying to make a difference in their specific fields in terms of environmental impact, saving and using energy properly, and the importance of conscientious eating. The documentary film has taken the concept of CSR and attempted to present it to a massive audience in order to suggest the idea that all of our actions eventually come back to us. Any imbalance in the system that surrounds us and which we are a part of will affect us. In contrast, any improvement to the system will benefit us. The film thus attempts to showcase testimonials by the main characters suggesting small changes we can make in our daily lives in order to work toward this goal. / text
177

Wave motion simulation using spectral elements and a hybrid PML formulation

Thakur, Tapan 08 July 2011 (has links)
We are concerned with forward wave motion simulations in two-dimensional elastic, heterogeneous, semi-infinite media. We use Perfectly Matched Layers (PMLs) to truncate the semi-infinite extent of the physical domain to arrive at a finite computational domain. We use a recently developed hybrid formulation, where the Navier equations for the interior domain are coupled with a mixed formulation for an unsplit-field PML. Here, we implement the hybrid formulation using spectral elements, and report on its performance. The motivation stems from the following considerations: Of concern is the long-time instability that has been reported even in homogeneous and isotropic cases, when the standard complex-stretching function is used in the PML. The onset of the instability is always within the PML zone, and it manifests as error growth in time. It has been suggested that the instability arises when waves impinge at grazing angle on the PML-interior domain interface. Yet, the instability does not always appear. Furthermore, different values of the various PML parameters (mesh density, attenuation strength, order of attenuation function, etc) can either hinder or delay the onset of the instability. It is thus conjectured that the instability is associated with the spectral properties of the discrete operators. In this thesis, we report numerical results based on both Lagrange interpolants, and results based on spectral elements. Spectral elements are explored since they lead to diagonal mass matrices, have improved dispersion error, and, more importantly, have different spectral properties than Lagrangian-based finite elements. Spectral elements are thus used in an attempt to explore whether the reported instability issues could be alleviated. We design numerical experiments involving explosive sources situated at varying depths from the surface, capable of inducing grazing-angle waves. We use the energy decay as the primary metric for reporting the results of comparisons between various spectral element orders and classical Lagrange interpolants. We also report the results of parametric studies. Overall, it is shown that the spectral elements alone are not capable of removing the instability, though, on occasion, they can. Careful parameterization of the PML could also either remove it or alleviate it. The issue remains open. / text
178

Habit-forming : reading Infinite jest as a rhetoric of humility

Gerdes, Kendall Joy 26 July 2011 (has links)
In this project, I argue that David Foster Wallace's 1996 novel Infinite jest (or IJ) is both about recovering from addiction through humility, and also it produces that humility in some of its readers by making us feel ourselves to be addicts to a certain kind of reading: a reading to find closure, certainty, and resolution. But, in frustrating the desires for closure, certainty, resolution, etc., IJ denies readers the satisfaction of completing the fix. It is precisely this denial that prompts readers to re-read, repeating the structure of addiction--but also destructuring it, by installing habits of reading that pleasure in the failure to close, the uncertainty, the impossibility of resolution--habits which I treat as humility. Following a thread in the performative theory of J.L. Austin, Jacques Derrida, and Eve Kosofsky Sedgwick, I clear space for reconceptualizing the performative utterance through an unusual example of a performative utterance: I take IJ to be the utterance of humility. Drawing on Avital Ronell's "narcoanalysis" in Crack wars, I argue that IJ's performative or substantializing work is in exploiting one kind of habit (addiction) in order to replace it with another (humility). The rhetorical transformation (to humility) effects itself through IJ's performative formation (in the reader) of the humbled habit. This project is a reading of a performative utterance (IJ) that produces a rhetorical effect, which effect is the formation of the habit of humility. / text
179

Verifying Absence of ∞ Loops in Parameterized Protocols

Saksena, Mayank January 2008 (has links)
The complex behavior of computer systems offers many challenges for formal verification. The analysis quickly becomes difficult as the number of participating processes increases. A parameterized system is a family of systems parameterized on a number n, typically representing the number of participating processes. The uniform verification problem — to check whether a property holds for each instance — is an infinite-state problem. The automated analysis of parameterized and infinite-state systems has been the subject of research over the last 15–20 years. Much of the work has focused on safety properties. Progress in verification of liveness properties has been slow, as it is more difficult in general. In this thesis, we consider verification of parameterized and infinite-state systems, with an emphasis on liveness, in the verification framework called regular model checking (RMC). In RMC, states are represented as words, sets of states as regular expressions, and the transition relation as a regular relation. We extend the automata-theoretic approach to RMC. We define a specification logic sufficiently strong to specify systems representable using RMC, and linear temporal logic properties of such systems, and provide an automatic translation from a specification into an analyzable model. We develop acceleration techniques for RMC which allow more uniform and automatic verification than before, with greater power. Using these techniques, we succeed to verify safety and liveness properties of parameterized protocols from the literature. We present a novel reachability based verification method for verification of liveness, in a general setting. We implement the method for RMC, with promising results. Finally, we develop a framework for the verification of dynamic networks based on graph transformation, which generalizes the systems representable in RMC. In this framework we verify the latest version of the DYMO routing protocol, currently being considered for standardization by the IETF.
180

??tude des propri??t??s physiques du Sr[indice inf??rieur 0,9]Nd[indice inf??rieur 0,1]Cu0[indice inf??rieur 2] en couches minces d??pos??es par ablation laser puls??

Olivier, Laurent January 2014 (has links)
Les chercheurs savent depuis longtemps que la supraconductivit?? est engendr??e par le couplage de paires d?????lectrons, appel??es paires de Cooper. Par contre, l???origine de l???inter-action conduisant ?? l???attraction effective entre les ??lectrons formant les paires demeure mal comprise pour certains mat??riaux d??couverts durant les trente derni??res ann??es. Dans ce m??moire, la supraconductivit?? a ??t?? induite dans des cuprates dop??s aux ??lectrons faisant partie de la famille des infinite-layers (IL), ayant la forme Sr[indice inf??rieur 1???x]Nd[indice inf??rieur x]CuO[indice inf??rieur 2]. Les IL ne peuvent ??tre d??pos??s en couches minces par la technique d???ablation laser que depuis tr??s r??cemment. L?????tude syst??matique de ces compos??s reste donc enti??rement ?? accomplir. Les IL ont ??galement une structure cristalline extr??mement simplifi??e qui facilite l???interpr??tation des ph??nom??nes physiques mesur??s en laboratoire. L?????tude des IL est un v??ritable tour de force. Plusieurs groupes de recherche dans le monde tentent de les synth??tiser en couches minces avec beaucoup de difficult??. Ces mat??riaux sont m??tastables et d???une sensibilit?? d??concertante. Obtenir des couches minces exemptes de phases parasites est un travail de longue haleine. Ce d??fi a non-seulement ??t?? relev??, mais il a ??t?? possible de r??aliser de la microfabrication sur les couches minces crues, rendant toute caract??risation des propri??t??s de transport beaucoup plus pr??cise. L???ablation laser puls??e est la technique qui a ??t?? utilis??e pour faire la croissance des couches minces ??tudi??es. La diffraction des rayons-X a permis l???identification des phases de la structure cristalline, mais surtout l?????tude des propri??t??s structurales des couches minces d??pos??es. Une analyse des param??tres en plan (a) et hors plan (c) de la cellule unit?? de ces couches minces en fonction des conditions de croissance s???est av??r??e essentielle. Il a ??t?? remarqu?? que le param??tre hors plan joue un r??le limitant dans l?????mergence de la supraconductivit??. Des mesures de r??sistivit?? ?? tr??s basses temp??ratures et sous champs magn??tiques intenses ont permis d?????tablir un lien entre l???apparition de la supraconductivit?? et la grandeur du param??tre hors plan de la structure cristalline. Une transition compl??te ne semble ??tre possible que lorsque le param??tre hors plan se trouve sous une grandeur critique, c = 3,41[A rond majuscule]. Des mesures d???effet Hall en fonction de la temp??rature sur des ??chantillons ayant diff??rentes valeurs du param??tre hors plan ont permis de d??terminer l?????volution des porteurs de charges pr??sents en fonction de c. Les ??chantillons supraconducteurs sugg??rent que la pr??sence de trous comme porteurs de charge est essentielle ?? l?????mergence de la supraconductivit??. Leur pr??sence semble diminuer rapidement ?? partir d???un param??tre hors plan plus grand que 3,41[A rond majuscule]. Il est possible d?????tablir un lien fondamental entre le comportement de la densit?? observ?? et celui d???une autre famille de supraconducteurs, les dop??s aux ??lectrons ayant une structure T???.

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