This review paper starts by setting out the aims and applications of power electronics, and continues with a brief history and a list of the important power semiconductor devices. The related areas of ac machines and power systems are also briefly visited. The development of nonlinear dynamics in electronic circuits is reviewed. Then a typical power converter, a controlled buck dc-dc converter, is modelled by the conventional method of averaging and linearisation (which predicts stability), and by a nonlinear map based method, which reveals bifurcations, subharmonics and chaos. The numerical problems caused by the discontinuities in the state equations of power electronics are discussed. Finally, some possible future applications are considered. 1 Introduction to Power Electronics M ost branches of electronics are concerned with processing information or signals; in contrast, power electronics deals with the processing of electrical energy. Power converters do not have an end of

Body Area Networks (BANs) are networks of medical devices implanted within or worn on the human body. Analysis and verification of BAN designs require: i) early feedback on the BAN design; and ii) high-confidence evaluation of BANs without requiring any hazardous, intrusive, and costly deployment. Any design of BAN further has to ensure: i) the safety of the human body, i.e. limiting any undesirable side-effects (e.g. heat dissipation) of BAN operations (involving sensing, computation, and communication among the devices) on the human body; and ii) the sustainability of the BAN operations, i.e. the continuation of the operations under constrained resources (e.g. limited battery power in the devices) without requiring any re-deployments. This paper uses the Model Based Engineering (MBE) approach to perform design and analysis of BANs. In this regard, first, an abstract cyber-physical model of BANs, called BAN-CPS, is proposed that captures the undesirable side-effects of the medical devices (cyber) on the human body (physical); second, a design and analysis tool, named BAND-AiDe, is developed that allows specification of BAN-CPS using industry standard Abstract Architecture Description Language (AADL) and enables safety and sustainability analysis of BANs; and third, the applicability of BAND-AiDe is shown through a case study using both single and network of medical devices for health monitoring applications.

v Table of Contents vii List of Tables xii List of Figures xiii 1. Introduction and Overview 1 1.1 Motivating Overview : : : : : : : : : : : : : : : : : : : : : : : : 1 1.2 Specific Benefits of Qualitative-Quantitative Simulation : : : : : 4 1.3 Previous work : : : : : : : : : : : : : : : : : : : : : : : : : : : : 7 1.3.1 Qualitative-quantitative work in VLSI : : : : : : : : : : 7 1.3.2 Qualitative-quantitative spatial reasoning : : : : : : : : : 8 1.3.3 Qualitative-Quantitative work in temporal ordering : : : 8 1.3.4 Interval and inequality reasoning : : : : : : : : : : : : : 9 1.3.5 Qualitative-quantitative simulation work : : : : : : : : : 10 1.4 Outline of Remaining Chapters : : : : : : : : : : : : : : : : : : 14 2. Q2: Adding Interval Information to Qualitative Simulation 15 2.1 Overview : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 15 2.2 Propagation of Incomplete Quantitative Information : : : : : : : 16 2.2.1 Types of quantitative propagation constrain...

Are fault simulation techniques feasible and effective for fault diagnosis of analog circuits ? In this paper, we investigate these issues via a software tool which can generate testability metrics and diagnostic information for analog circuits represented by SPICE descriptions. This tool, termed the Virtual Test-Bench (VTB), incorporates three different simulation-based techniques for fault detection and isolation. The first method is based on the creation of fault-test dependency models, while the other two techniques employ machine learning principles based on the concepts of: (1) Restricted Coloumb Energy (RCE) Neural Networks, and (2) Learning Vector Quantization (LVQ). Whereas the output of the first method can be used for the traditional off-line diagnosis, the RCE and LVQ models render themselves more naturally to on-line monitoring, where measurement data from various sensors is continuously available. Since it is well known that analog faults and test measurements are affecte...

In recent years, interest in the area of custom computing machines (CCMs) has been on a steady increase. Much of the activity surrounding CCMs has centered around Field-Programmable Gate Array (FPGA) technology and rapid prototyping applications. While higher performance has been a concern in some applications, the solutions are limited by the relatively small FPGA bandwidth, density and throughput. This leads to area, speed, power, and application-specific constraints. In recent months, an integrated circuit known as the VT Colt has been developed to address some high performance digital signal processing (DSP) problems that conventional processors, CCMs, and ASICs cannot do under the space and power constraints. The Colt chip takes a data-flow approach to processing and is highly reconfigurable to suit the many computationally demanding tasks that new DSP applications present. A significant portion of the development of the Colt chip is architectural justification, functional verification, and configurability. This thesis explores verification of the Colt chip at various levels of development including mapping arithmetic computations and DSP algorithms that the Colt architecture was designed to solve. ACKNOWLEDGEMENTS I would like to thank my advisor, Dr. Peter Athanas, for giving me the opportunity to work

A practical, 'user-friendly' methodology is developed to study the behavior of current-shared converters. It applies average modeling, analysis and simulation to examine the static conditions and small-signal stability of converters that operate in Average Current Sharing (ACS) mode. Simple expressions for stability criterion were developed and applied to assess the influence of the number of paralleled modules on the stability and dynamics of the converters system. I. INTRODUCTION Paralleling of DC-DC converters has many desirable features: increased reliability, expandability and on-site repair when hot plug-in capability is incorporated. However, the analysis and design of parallel converters are far from being simple due to the fact that they are no longer of the singleinput single-output type [1-6]. For increased reliability, paralleled converters require a Current Sharing (CS) mechanism to ensure distribution of currents and stresses between the modules. Unfortunately, the CS co...

Distributed-circuit analysis using transmission lines is a standard topic in undergraduate education in electrical engineering and computer engineering. This paper presents a simple menu-driven program that students can use to explore the behavior of transmission line circuits, and as a computational laboratory for verifying their solutions to homework problems. At the introductory level the program demonstrates traveling waves and standing waves. Smith-chart calculations of impedance and reflection coefficient can be associated with the standing-wave pattern on the transmission line. A branching circuit can be solved, including impedance matching with a quarter-wave transformer. At the intermediate level, students can use the program to test their designs for two- and three-step Chebyshev transformers, and for impedance matching using single, double and triple-stub circuits. The program makes easy the calculation of the bandwidth of a design by displaying the return loss or transmission loss as a function of frequency. Low-pass and bandstop filters can be solved. The program encourages students to explore the behavior of the voltages and currents on the lines as the frequency is changed to gain insight into the operation of transformers, matching schemes and filters.

This thesis introduces a novel application of factor graphs to the domain of analog circuits. It proposes a technique of leveraging factor graphs for performing statistical yield analysis of analog circuits that is much faster than the standard Monte Carlo/Simulation Program With Integrated Circuit Emphasis (SPICE) simulation techniques. We have designed a tool chain to model an analog circuit and its corresponding factor graph and then use a Gaussian message passing approach along the edges of the graph for yield calculation. The tool is also capable of estimating unknown parameters of the circuit given known output statistics through backward message propagation in the factor graph. The tool builds upon the concept of domain-specific modeling leveraged for modeling and interpreting different kinds of analog circuits. Generic Modeling Environment (GME) is used to design modeling environment for analog circuits. It is a configurable tool set that supports creation of domain-specific design environments for different applications. This research has developed a generalized methodology that could be applied towards design automation of different kinds of analog circuits, both linear and nonlinear. The tool has been successfully used to model linear amplifier circuits and a nonlinear Metal Oxide Semiconductor Field Effect Transistor (MOSFET) circuit. The results obtained by Monte Carlo simulationsiv performed on these circuits are used as a reference in the project to compare against the tool’s results. The tool is tested for its efficiency in terms of time and accuracy against the standard results. (104 pages) To my loving family and friends.... v vi

The advent of smart phone has enabled health care anywhere and anytime. With pervasive health care, a person can perform necessary day to day tasks while his or her health is recorded, controlled, and processed continuously using on body sensors and actuators to capture abnormalities, trends, and causes. In such a scenario of utmost importance is seamless operation of the pervasive health management system (PHMS), given frequent and dynamic changes in the context of the user. Such context changes dynamically affect the processing requirements of the health management application, the available energy sources, the interaction between a medical device with the human body and many more. For social acceptability of PHMSes, they have to be tested and verified for their safe, energy sustainable (long term) and reliable operation under such dynamically changing environment. This paper proposes a novel technique to analyze PHMSes taking into account the dynamic changes in the context and the constant interaction of the medical device with the human body.

The advent of smart phones has enabled health care anywhere and anytime. With pervasive health care, a person can perform necessary day to day tasks while his health is recorded, controlled, and processed continuously using on body sensors and actuators to capture abnormalities, trends, and causes. In such a scenario, seamless operation of the pervasive health management system (PHMS), given dynamic changes in the context induced by mobility of the user is of utmost importance. Such context changes dynamically affect many aspects such as the processing requirements of the health management application, the available energy sources, the interaction between a medical device with the human body. For social acceptability of PHMSes, they have to be tested and verified for their safe, energy sustainable (long term) and reliable operation under such dynamically changing environment. This paper proposes a novel technique to analyze PHMSes under mobility induced dynamic changes in the context and constant interaction of the medical device with the human body. Results show that human mobility induced context changes can cause unsafe conditions such as drug overdose.