This thesis is concerned with the modeling and numerical study of nonsmooth dynamical systems (NSDS). The first part of the thesis deals with the modeling of some DC-DC power converters using the complementarity formalism. This mathematical theoretical framework allows us to ensure existence and uniqueness of solutions in a "natural" and synthetic way. Specifically, it works pretty well in power electronic converters because it incorporates generalized discontinuous conduction modes (GDCM), characterized by a reduction of the dimension of the effective dynamics. For systems with a single diode, analytical state-space conditions for the presence of a GDCM are stated and simulation results, showing a variety of behaviours, such as persistent or re-entering GDCM, are also presented. Furthermore, the analysis and simulation of a parallel resonant converter (PRC), which has four diodes, illustrate the convenience of the complementarity formalism to simulate electrical systems with a large number of ideal diodes. We also present the simulation of a boost converter with a sliding mode control, even though a general control theory for complementarity systems is not still developed.In the second part of the thesis we focus on the bifurcation analysis in NSDS, and in particular, we have studied different mechanical systems which involve impacts and dry-friction. It is known that nonsmooth or discontinuous dynamical systems can exhibit the bifurcations also exhibited by smooth systems. In addition to these, there are also some novel transitions so-called discontinuity-induced bifurcations (DIBs) which are unique to these systems. We have investigated the complex behaviour occurring in an impacting mechanical system. DIBs such as corner impact bifurcations and transitions from complete to uncomplete chattering motions have been analysed in detail. Another type of DIBs recently classified are the so-called sliding bifurcations. Such bifurcations are a characteristic feature of so-called Filippov systems. We present detailed examples of all the different sliding bifurcation scenarios in a dry friction oscillator using a measured friction characteristic firstly introduced by Popp. Furthermore, a codimension-two degenerate switching-sliding bifurcation is displayed. In this case of degenerate switching-sliding bifurcation two curves of codimension-one sliding bifurcations, crossing-sliding and adding-sliding, branch out from the codimension-two point. Also, a cusp smooth codimension-two bifurcation is shown and coexistence of periodic orbits in the region between both fold codimension-one curves is studied.We have also investigated the dynamic behaviour of the two-block Burridge model for earthquake simulations. Previous numerical studies investigated by Ruina verified that, with a friction force of Coulomb type, the system presents only periodic behaviour. We show that chaotic regions can be observed in a symmetric configuration even if a Coulomb friction is considered with the relaxation of one of the assumptions assumed in the seismological literature. Furthermore, we have studied the behaviour of the system with asymmetric configuration. Different periodic solutions and regions of chaos can be observed varying the asymmetry of the system. With respect to the bifurcation point of view, we have analysed several smooth bifurcations (smooth and DIBs) observed in this system.Chapter 6 of this thesis presents the SICONOS software platform dedicated to simulation of NSDS. We give an overview of the SICONOS software and the way NSDS are modeled and simulated within the platform. Routines for analysis (stability, bifurcations, invariant manifolds,.) of NSDS implemented in the platform are explained in detail. To conclude this part, several representative samples are shown in order to illustrate the SICONOS platform abilities.Conclusion and some open problems are presented in the last chapter.

Silicon Germanium BiCMOS technology has been demonstrated as an ideal platform for highly integrated systems requiring both high performance analog and RF circuits as well as large-scale digital functionality. Frequency synthesizers are ideal candidates for this technology because the mixed-signal nature of modern frequency synthesis designs fundamentally requires both digital and analog signal processing. This research targets three areas to improve SiGe frequency synthesizers. A majority of this work focuses on applying SiGe frequency synthesizers to extreme environment applications such as space, where low temperatures and ionizing radiation are significant design issues to contend with. A second focus area involves using SiGe HBTs to minimize noise in frequency synthesizer circuits. Improved low frequency "pink" noise in SiGe HBTs provide a significant advantage over CMOS devices, and frequency synthesis circuits are significantly affected by this type of noise. However, improving thermal "white" noise is also considered. Finally, an analysis of AM-PM distortion is considered for SiGe HBTs. The studies presented focus on identifying the physical mechanisms of observed phenomena, such as single event transients or phase noise characteristics in oscillators. The ultimate goal of this research is to provide a reference of effective design parameters for circuit and system designers seeking to take advantage of the properties of SiGe device physics.

This master thesis is a portion of the DySCAS project and work is performed at Enea AB. DySCAS (Dynamically Self-Configuring Automotive Systems) is a research project funded by the European This thesis concentrates on future vehicle electronic systems. During a life cycle of the car vehicle manufacturers desire to upgrade or add new functions into the vehicle electronic systems, this is not possible with the static-runtime environment that employed into today’s car. To tackle this difficult problem many technologies were gathered and a dynamically self-configuring automotive system was introduced by combining technologies like self-managing, service-based and middleware. The obtained results fulfilled most of DySCAS requirements. However, the system has a few limitations and these are caused by the immature of distributed reconfigurable embedded systems in the market.

As integrated circuits and printed circuit boards increase in complexity, testing becomes a major cost factor of the design and production of the complex devices. Testability has to be considered during the design of complex electronic systems, and automatic test systems have to be used in order to facilitate the test. This fact is now widely accepted in industry. Both design for testability and the usage of automatic test systems aim at reducing the cost of production testing or, sometimes, making it possible at all. Many design for testability methods and test systems are available which can be configured into a production test strategy, in order to achieve high quality of the final product. The designer has to select from the various options for creating a test strategy, by maximising the quality and minimising the total cost for the electronic system. This thesis presents a methodology for test strategy generation which is based on consideration of the economics during the life cycle of the electronic system. This methodology is a concurrent engineering approach which takes into account all effects of a test strategy on the electronic system during its life cycle by evaluating its related cost. This objective methodology is used in an original test strategy planning advisory system, which allows for test strategy planning for VLSI circuits as well as for digital electronic systems. The cost models which are used for evaluating the economics of test strategies are described in detail and the test strategy planning system is presented. A methodology for making decisions which are based on estimated costing data is presented. Results of using the cost models and the test strategy planning system for evaluating the economics of test strategies for selected industrial designs are presented.

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Electrical and Computer Engineering, 2009. / Includes bibliographical references.

Increasing power dissipation and chip densities in the rapidly evolving electronics cooling industry are causing an ever increasing need for the tools and methods necessary for electronic systems design and optimisation. Modern electronic systems have the capacity to produce significant amounts of heat which, if not removed efficiently, could lead to component failure. The most common technique of heat removal is by making use of a heat spreader, or so¬-called heat sink. These devices are excellent heat conductors with a large surface area to volume ratio, and cooled through either natural or forced convection. Despite the advantages of these devices, there are serious consequences involved in the application of heat sinks. The required size of a heat sink may limit the miniaturisation of a product, while inadequate design, due to a lack of understanding of the flow physics, may lead to premature component failure. It is therefore crucial that an optimal heat sink design is achieved for every particular application. In the past, both heat sink design and optimisation have occurred mostly through experimental characterisation of heat sinks, which was not always particularly successful or accurate. Recent rapid developments in computer technology have led to the availability of various computational fluid dynamics or CFD software packages, with the capability of solving the discretized form of the conservation equations for• mass, momentum, and energy to provide a solution of the flow and heat fields in the domain of interest. This method of using the fundamental flow physics is currently the most complete way to determine the solution to the heat sink design and optimisation problem. It does unfortunately have the drawback of being computationally expensive and excessively time consuming, with commercial software prices being financially restrictive to the average designer. The electronics cooling community has subsequently identified the need for so-called "compact models" to assist in the design of electronic enclosures. Compact models use available empirical relations to solve the flow field around a typical heat sink. Current models require significantly less computational power and time compared to CFD analysis, but have the drawback of reduced accuracy over a wide range of heat sink geometries and Reynolds numbers. This is one of the reasons that compact modelling of heat sinks remain an international research topic today. This study has focused on the CFD modelling of a variety of forced flow longitudinal fin heat sinks with tip clearance. Tip clearance allows the flow to bypass the heat sink and downgrade its thermal performance. The flow bypass phenomenon, general flow behaviour, and pressure loss characteristics were investigated in detail. Thermal modelling of the heat sinks was left for future study. The flow information provided by the CFD analysis was combined with data available from literature to develop an improved compact flow model for use in a variety of practical longitudinal fin heat sinks. The new compact model leads to a 4.6 % improvement in accuracy compared to another leading compact model in the industry, and also provides more localised flow information than was previously available from compact modelling. <p The study therefore contributed significantly towards the general understanding and prediction of forced flow behaviour in longitudinal fin heat sinks with tip bypass, using both CFD analysis and the compact modelling approach. The new improved compact model may now be extended and incorporated together with the relevant flow details from the CFD analysis in a total package, solving for the flow and heat fields of forced flow longitudinal fin heat sinks. The study therefore assists in the global effort of making the confident and accurate use of compact modelling in modem electronic systems design and optimisation a practical reality. / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

Orientador: Amir Ordacgi Caldeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-27T16:19:57Z (GMT). No. of bitstreams: 1 Trevisan_ThaisVicta_M.pdf: 4124547 bytes, checksum: 599b58df77b4451dd1db391d5d3f78fd (MD5) Previous issue date: 2015 / Resumo: Na presença de um campo magnetico externo, um anel, com resistencia eletrica nao nula, sustenta uma corrente eletrica sem dissipacao, desde que ele seja sufientemente pequeno (com um diametro da ordem de micrometros ou nanometros), altamente puro e mantido a baixisimas temperaturas. Trata-se de um fenomeno quantico, devido a coerencia entre os eletrons do sistema. Uma corrente desse tipo tambem esta presente em moleculas aromaticas: um loop de corrente se estabelece no anel aromatico e e o responsavel pela anisotropia da susceptibilidade magnetica dessas moleculas. Atualmente, esses aneis de corrente sao utilizados como um criterio para aromaticidade. Assim sendo, o transporte de corrente eletrica em sistemas meso e microscopicos e um assunto de grande interesse tanto para a Fisica, quanto para a Quimica. Nessa Dissertacao de Mestrado, estudamos o transporte de corrente eletrica em aneis discretos, unidimensionais, de 3 [<ou =] N [<ou=] 6 sitios e Ne [<ou=] 2N eletrons. Esses aneis podem ser vistos como moleculas bastante simplificadas, de modo que o sistema de seis sitios com seis eletrons corresponde a um prototipo da molecula de benzeno. Propomos um modelo microscopico com a finalidade de obter um estado fundamental transportador de corrente nesses aneis. O nosso modelo consiste de uma extensao do Hamiltoniano de Hubbard, com um termo extra de interacao inter-eletronica, postulado de maneira ad hoc. Os resultados obtidos a partir do nosso modelo, bem como uma possivel origem e interpretacao para o termo extra de interacao sao apresentados ao longo desse trabalho / Abstract: In the presence of an external magnetic feld, a ring, with finite electrical resistance, supports a dissipationless electric current, provided that the ring is small enough (its diameter must be of the order of some micrometer or nanometer), clean and cooled down to very low temperatures. It is a quantum phenomena, due to the high electronic phase coherence in this system. A current like this can also be seen in aromatic molecules: a loop of current is established in the aromatic ring and it is the responsible for the high anisotropic magnetic susceptibility of these molecules. Nowadays, these ring currents are used as a criteria for aromaticity. Therefore, the electrical transport properties in mesoscopic and microscopic systems is a subject of great interest both in Physics and Chemistry. In this thesis, we study the electrical transport in some discrete and unidimensional rings with 3 [<or=] N [<or=] 6 sites and Ne [<or=] 2N electrons. These rings can be seen as simplified molecules and the ring with six sites and six electrons is our prototype for the benzene molecule. We propose a microscopic model for obtaining a current-carrying ground state in these rings. Our model consists of a extension of the Hubbard Hamiltonian, with an ad hoc extra term for the interaction between the electrons of the system. The results obtained from our model as well as a possible origin and interpretation of the extra interaction term are presented throughout this work / Mestrado / Física / Mestra em Física

The technological development is enabling production of increasingly complex electronic systems. All those systems must be verified and tested to guarantee correct behavior. As the complexity grows, testing is becoming one of the most significant factors that contribute to the final product cost. The established low-level methods for hardware testing are not any more sufficient and more work has to be done at abstraction levels higher than the classical gate and register-transfer levels. This thesis reports on one such work that deals in particular with high-level test generation and design for testability techniques. The contribution of this thesis is twofold. First, we investigate the possibilities of generating test vectors at the early stages of the design cycle, starting directly from the behavioral description and with limited knowledge about the final implementation architecture. We have developed for this purpose a novel hierarchical test generation algorithm and demonstrated the usefulness of the generated tests not only for manufacturing test but also for testability analysis. The second part of the thesis concentrates on design for testability. As testing of modern complex electronic systems is a very expensive procedure, special structures for simplifying this process can be inserted into the system during the design phase. We have proposed for this purpose a novel hybrid built-in self-test architecture, which makes use of both pseudorandom and deterministic test patterns, and is appropriate for modern system-on-chip designs. We have also developed methods for optimizing hybrid built-in self-test solutions and demonstrated the feasibility and efficiency of the proposed technique. / <p>Report code: LiU-Tek-Lic-2002:46.</p>

University of Macau / Faculty of Science and Technology / Department of Electrical and Electronics Engineering

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.