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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.
41

Solutions variationnelles et solutions de viscosité de l'équation de Hamilton-Jacobi / Variational and viscosity solutions of the Hamilton-Jacobi equation

Roos, Valentine 30 June 2017 (has links)
On étudie l'équation de Hamilton-Jacobi évolutive du premier ordre, couplée avec une donnée initiale lipschitzienne. Le but est de comparer les solutions de viscosité et les solutions variationnelles pour cette équation, deux notions de solutions faibles qui coïncident en dynamique hamiltonienne convexe. Pour travailler dans un cadre pertinent pour les deux types de solutions, on doit d’abord construire une solution variationnelle sans hypothèse de compacité sur la variété ou le hamiltonien étudiés. On retrace dans ce cas la construction historique des solutions variationnelles, en détaillant les propriétés de la famille génératrice obtenue par la méthode des géodésiques brisées. Il en découle des estimées permettant d’obtenir la solution de viscosité à partir de la solution variationnelle par un procédé d’itération. Après avoir vérifié que la solution variationnelle construite coïncide effectivement avec la solution de viscosité pour un Hamiltonien convexe, on caractérise les Hamiltoniens intégrables pour lesquels cette propriété persiste, en étudiant attentivement des exemples élémentaires en dimension 1 et 2. / We study the first order Hamilton-Jacobi equation associated with a Lipschitz initial condition. The purpose of this thesis is to compare two notions of weak solutions for this equation, namely the viscosity solution and the variational solution, that are known to coincide in convex Hamiltonian dynamics. In order to work in a relevant framework for both notions, we first need to build a variational solution without compactness assumption on the manifold or the Hamiltonian. To do so, we follow the historical construction, detailing properties of the generating family obtained via the broken geodesics method. Local estimates allow to prove that the viscosity solution can be obtained from the variational solution via an iterative process. We then check that this construction gives effectively the viscosity solution for a convex Hamiltonian, and characterize the integrable Hamiltonians for which this property persists by carefully studying elementary examples in dimension 1 and 2.
42

Device-Circuit Co-Design Employing Phase Transition Materials for Low Power Electronics

Ahmedullah Aziz (7025126) 12 August 2019 (has links)
<div> <div> <p>Phase transition materials (PTM) have garnered immense interest in concurrent post-CMOS electronics, due to their unique properties such as - electrically driven abrupt resistance switching, hysteresis, and high selectivity. The phase transitions can be attributed to diverse material-specific phenomena, including- correlated electrons, filamentary ion diffusion, and dimerization. In this research, we explore the application space for these materials through extensive device-circuit co-design and propose new ideas harnessing their unique electrical properties. The abrupt transitions and high selectivity of PTMs enable steep (< 60 mV/decade) switching characteristics in Hyper-FET, a promising post-CMOS transistor. We explore device-circuit co-design methodology for Hyper-FET and identify the criterion for material down-selection. We evaluate the achievable voltage swing, energy-delay trade-off, and noise response for this novel device. In addition to the application in low power logic device, PTMs can actively facilitate non-volatile memory design. We propose a PTM augmented Spin Transfer Torque (STT) MRAM that utilizes selective phase transitions to boost the sense margin and stability of stored data, simultaneously. We show that such selective transitions can also be used to improve other MRAM designs with separate read/write paths, avoiding the possibility of read-write conflicts. Further, we analyze the application of PTMs as selectors in cross-point memories. We establish a general simulation framework for cross-point memory array with PTM based <i>selector</i>. We explore the biasing constraints, develop detailed design methodology, and deduce figures of merit for PTM selectors. We also develop a computationally efficient compact model to estimate the leakage through the sneak paths in a cross-point array. Subsequently, we present a new sense amplifier design utilizing PTM, which offers built-in tunable reference with low power and area demand. Finally, we show that the hysteretic characteristics of unipolar PTMs can be utilized to achieve highly efficient rectification. We validate the idea by demonstrating significant design improvements in a <i>Cockcroft-Walton Multiplier, </i>implemented with TS based rectifiers. We emphasize the need to explore other PTMs with high endurance, thermal stability, and faster switching to enable many more innovative applications in the future.</p></div></div>
43

New Generation 4-Channel GNSS Receiver : Design, Production, and Testing

Antoja Lleonart, Guillem January 2018 (has links)
Due to the current research needs and the lack of commercial multi-channel, multi-constellation GNSS receivers, a two-board solution has been developed so it can be mated with and take advantage of the processing power of the FPGA board branded as MicroZed. In order to achieve the proposed goals, an initial phase for assessing and updating the older design, building, and testing of SiGe modules (including both the electronics and casings) has been carried out. The results included demonstrate performances at logging GPS-L1 data with similar C/N0 and AGC values as the previous versions of the modules and offering navigation solutions with accuracies of a few meters. Secondly, a first iteration and design proposal for the new generation receiver has been proposed for GPS and GLONASS L1 and L2, which has been manufactured and tested. Partial tests have been performed due to the flaws of the current revision of the MicroZed Board in regards to its communication peripherals, and the results have validated the receiver’s design provided certain modifications are considered for future iterations. Furthermore, voltage and frequency tests have provided results with an error of less than 7%, and signal tests have provided C/N0 values similar to those of the SiGe modules of around 47[dB-Hz] which will be a useful baseline for future iterations. Finally, a design proposal for an Interface Board used between the older NT1065_PMOD Board and other FPGA boards carrying the standardized FMC connectors has been added to the report and negotiations with manufacturers have been engaged.
44

Multigramatiky a syntaktická analýza založená na nich / Multigrammars and Parsing Based on Them

Fiala, Jiří Unknown Date (has links)
This document deals with introduction focused on pragmatically oriented research at branch of theoretical computer science and with presentation of designed methods for chosen application topics. At this study the theoretical subject is represented by kind of generative system - multisequential grammar and application topics are chosen according to possibilities supported by multisequential grammars. In order to follow results published by Thompson (see [9]), Lindenmayer (see [26]), Mandelbrot (see [8]) and also studies published by Morneau (see [17]), which shows the relation between natural laws and human discipline - mathematics, we study the applications of multi-sequential grammars from two points of view: generative L-systems (which further includes applications of fractal geometry and biomathematics) and natural language processing (which further includes the design of proper abstract language). Some problems related to compiler construction are also mentioned.
45

Produktionsoptimering av elektromagnetiska omrörare - "ORD 43P" och "EM Stabilizer"

Kabroo, Carl Gustaf, Willenius, Robert January 2013 (has links)
Examensarbetet inom produktutveckling – konstruktion utfördes under perioden februari till juni 2013 och omfattar 15 högskolepoäng (C-nivå), och är den slutliga kursen inom högskoleingenjörsprogrammet Innovation och produktdesign. Examensarbetet behandlade problematiken kring produktionsanpassning och kostnadsoptimering av två stycken elektromagnetiska omrörare vid företaget ABB, Process Automation, Metallurgy i Västerås. Efter kontakt med handledaren från ABB, Jan-Erik Eriksson, påbörjades projektarbetet med att tillverkningsanpassa konstruktionen av produkterna ORD 43P och EM Stabilizer. För att åstadkomma kostnadsoptimerad och produktionsanpassad konstruktion tillämpade författarna följande produktutvecklingsverktyg: Design for Cost, Design for Manufacture och Design for Assembly. För att kontrollera att konstruktionen blev optimal, men också att den inte brister under belastning använde examensarbetarna det datorbaserade hållfasthetsverktyget finita elementmetoden i CAD-programmet SolidWorks. Val av komponenter baserades på komponenternas pris per kilo. För att välja det optimala materialet, det vill säga högsta hållfasthet till lägsta pris använde författarna materialdatabasprogrammet CES EduPack. De utvalda materialen från programmet kunde inte författarna påfinna som standard på marknaden, varför författarna ändrade strategi till att jämföra och välja material utifrån marknadsundersökning av standardmaterial hos leverantörer.   ORD 43Ps komponenter optimerades konstruktionsmässigt gentemot befintliga komponenter och härvstag och isolerplattor kostnadsreducerades markant. Komponenten stomme grundutförande undersöktes översiktligt.  Genom att produktutveckla komponenterna härvstag, isolerplattor och stomme grundutförande minskade kostnaderna för ORD 43P med 2,47 %.  Författarna ansåg att ORD 43Ps totala kostnader kan minska mellan 10-25 % eftersom många av dess komponenter är överdimensionerade och består av dyrare material än vad som krävs.  EM Stabilizer’s komponenter, lock och tryckluftsslang, utformades med optimal konstruktion och kostnadsreducerades.  Genom att produktutveckla komponenterna lock och tryckluftsslang minskade kostnaderna för EM Stabilizer med 1,3 %.  Författarna förmodar att EM Stabilizer’s kostnader kan minska, eftersom den är relativt ny på marknaden. ABB vill säkerställa att produkten uppnår sin garanterade livslängd genom att överdimensionera många av produktens komponenter och använda dyrare material än vad som är nödvändigt. / The thesis in product development – design was carried out between February and June 2013 and includes 15 credits (C-level), and is the final course of the Bachelor Program in Engineering, Innovation and Product Design.  The thesis dealt with the problem of adaptation to production and cost optimization of two pieces of electromagnetic stirrers at the company ABB, Process Automation, Metallurgy in Västerås. After contact with the supervisor from ABB, Jan-Erik Eriksson, the project work commenced to adapt the manufacturing design of the product ORD 43P and EM Stabilizer. To achieve cost-optimized production and production adapted design, the authors applied the following product development tools: Design for Cost, Design for Manufacture and Design for Assembly. To verify that the design was optimal, but also that it did not break during stress, the authors used the computer based module finite element method of the CAD program SolidWorks.  The selection of components was based on the component’s price per kilo.  To select the optimum material, that is high strength and affordable, the authors used the material database software CES EduPack. The materials selected from CES EduPack could not be found by the authors as standard material at the market. Therefore, the authors changed strategy to compare and select materials based on market research of standard materials with suppliers. The components of ORD 43P were optimized in terms of design in comparison with existing components coil bracket and insulation boards. They were also cost reduced significantly. The component frame base was examined briefly.  Through product development the components coil bracket, insulating boards and frame base the total cost of ORD 43P was reduced by 2,47 %.  The authors found that the total cost of ORD 43P could be reduced between 10-25 % as many of its components are oversized and made ​​of more expensive materials than needed.  The components of EM Stabilizer, cover and pneumatic hose, were designed with optimum design and was cost reduced.Through product development the components cover and pneumatic hose the costs of EM stabilizer were reduced by 1,3 %.  The authors assume that the costs of the EM Stabilizer can be reduced, because it is relatively new at the market. ABB want to ensure that the product reach its guaranteed life by over-sizing many of the components of the product and use more expensive material than necessary. / Kostnadssänkningsprojekt

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