Efficient Macromodeling and Fast Transient Simulation of High Speed Distributed Interconnects

In the first part of the thesis, an efficient macromodeling technique based on Loewner Matrix (LM) approach has been presented to model multi-port distributed systems using tabulated noisy data. In the proposed method, Loewner Model data from previous rational approximation are used to create less noisy eigenvectors in an iterative manner. As a result, the biasing effect of the LM model approximated by the noisy data is reduced. It is illustrated that this method improves the accuracy of the Loewner Matrix modeling for noisy frequency data. In the second part, a fast and robust algorithm is introduced for time-domain simulation of interconnects with few nonlinear elements based on Large Change Sensitivity approach. After macromodeling interconnects, linear parts of the system construct very large matrix. Large linear matrix with nonlinear components makes time domain simulation a Central Processing Unit (CPU) intensive task where inversion (one Lower/Upper (LU) decomposition and one forward/backward substitution) of this large matrix is done at each step of the Newton-Raphson iteration. Using the proposed method, large system matrix is partitioned into linear and nonlinear parts and LU decomposition of linear matrix is done only once in the entire simulation. Nonlinear elements construct a very small matrix compared to large linear matrix. In this proposed method, small matrix is inverted at each Newton iteration. Cost of inverting a small matrix is much cheaper than inverting a very large matrix. Therefore, this approach is faster than the conventional matrix inversion method. Numerical examples are presented illustrating validity and efficiency of the above method

Time-domain Analysis of Multiconductor Transmission Lines Excited by Transient Electromagnetic Disturbances Based on the Analog Behavior Modeling

L'abstract è presente nell'allegato / the abstract is in the attachmen

Circuit models of shielded single and multiconductor cables for EMC analyses

In dieser Arbeit werden neuartige Schaltungsmodelle für Koaxialkabel mit Geflechtschirm über einer Masseebene vorgestellt. Die Modelle sind aus der Leitungstheorie abgeleitet und eignen sich zur Integration in SPICE-Simulationsprogramme. Es werden zwei Arten von Modellen vorgestellt. Zuerst wird ein konzentriertes Schaltungsmodell (lumpedcircuit model) erklärt, bei dem das Kabel in kleine Abschnitte unterteilt ist, wobei jeder Abschnitt durch ein Ersatzschaltbild ersetzt wird. Dann wird aus den analytischen Lösungen der Leitungstheorie ein Makromodell entwickelt, welches das gesamte Kabel ohne Diskretisierung darstellt. Diese Arbeit demonstriert die Effizienz des Makromodells in Bezug auf Rechenzeit und Genauigkeit im Vergleich zum konzentrierten Schaltungsmodell. Die entwickelten Schaltungsmodelle können die eingekoppelte Spannung an den Abschlüssen des Kabels berechnen, wenn eine einfallende ebene Welle in das Kabel eingekoppelt wird. Diese Modelle können auch die Kopplungen aufgrund von Störungen durch konzentrierte Quellen berechnen. Die entwickelten Modelle eignen sich daher für die Schaltungs-EMVAnalyse von Systemen, die geschirmte Kabel enthalten und anfällig für Feldeinkopplungen oder Störungen mit anderen Systemen sind. Die bidirektionale Kopplung zwischen der Innen- und Außenseite des Kabelschirms wird berücksichtigt, was die Analyse der Störfestigkeit und der Emission ermöglicht. Die mathematischen Funktionen zur Berechnung der Kopplung zwischen dem inneren und dem äußeren System des Kabels werden in Ersatzschaltungen umgewandelt, die den Einsatz der Modelle im Frequenzbereich oder zusammen mit nichtlinearen Elementen im Zeitbereich ermöglichen. Die entwickelten Modelle für ein einadriges geschirmtes Kabel werden im Rahmen dieser Arbeit für geschirmte mehradrige Kabel erweitert. Die Schaltungsmodelle werden durch Messungen und Feldsimulationen validiert, wobei die Ergebnisse eine sehr gute Übereinstimmung zeigen.In this thesis, novel circuit models for coaxial cables with braided shields placed above a ground plane are presented. The models are derived from the transmission line theory and are suitable for integration into SPICE simulation programs. Two types of models are presented. First, a lumped-circuit model is developed in which the cable is divided into small sections, with each section replaced with an equivalent circuit and connected to represent the entire cable. In the second type, a macromodel is developed from the analytical solutions of the transmission line theory to represent the entire cable without discretizing it. This work demonstrates the efficiency of the macromodel in terms of computing time and accuracy compared to the lumped-circuit model. The designed models can be used to calculate the induced voltage at the termination loads of the cable when an incident uniform plane wave is coupled in. These models can also calculate the coupling results due to interference from lumped sources. The developed models are therefore suitable for the circuit EMC analysis of systems that contain shielded cables and are susceptible to field coupling or interference with other systems. The bidirectional coupling between the inside and outside of the cable shield is taken into account, which enables the analysis of interference immunity and emissions. The mathematical functions for calculating the coupling between the inner and outer systems of the cable are transformed into equivalent circuit diagrams that allow the models to be used in the frequency domain or together with nonlinear elements in the time domain. The developed models for a single conductor shielded cable are expanded for shielded multiconductor cables within the scope of this work. The circuit models are validated by measurements and field simulations, and the results show excellent agreement

Analysis and synthesis of active transmission lines

Active transmission lines, a generalization of classical transmission lines, are useful electrical devices. They can be utilized to realize distributed amplifiers and to obtain other electrical characteristics unattainable with passive lines. Active lines have historical significance and model many physical processes including heat conduction in an internally heated material, a vibrating string, pressure waves in gas, neutron diffusion and fission, and semiconductor photodetection. This paper fully develops the analysis and synthesis of active transmission lines using a network theory approach. An active line is characterized by distributed series voltage and shunt current sources in addition to the passive line parameters. These sources may be of independent and/or dependent type. It is shown that independent sources may be removed from the line if appropriate modifications' in port conditions are made. Extraction integrals are formulated for this purpose. Examples of independent sources include initial condition generators; they also occur in devices exhibiting active coupling such as the traveling-wave transistor. Dependent sources however change the two-port parameters of the active line. These sources have their outputs controlled by either line voltage or current (a source at position x has an output which depends on either voltage or current at position x). Two basic types of lines are therefore possible. The uniform active line having dependent distributed sources is completely analyzed. Its traveling-wave characteristics including characteristic impedances and propagation functions are presented. Laplace transformation techniques are used to analyze the driving-point and transfer admittances, gain, bandwidth, step response, rise and delay time, and sensitivity of uniform rcg active lines. The general nature of the pole-zero patterns of nonuniform active lines having distributed dependent sources are investigated using several results from differential equation theory. Their two-port parameters are readily expressed using the basic set notation and self-adjoint properties of the active line equations. Lack of pole-zero cancellation is noted utilizing the Wronskian of the basic set solutions. Sturm-Liouville theory establishes the general pole-zero locations. many of the powerful theorems concerning lumped passive networks are seen to parallel those of active lines. Active transmission lines are readily synthesized directly in the time or frequency domain using variational calculus techniques. The parameter distributions required to produce specified port response for arbitrary excitations and loadings (consistent with parameter bounds, etc.) are generated by expressions involving voltage and current along the original line and a so-called adjoint line. The method is readily implemented by digital and hybrid computers. At the present time, active transmission lines cannot be realized because of the inability to distribute dependent sources along a passive line. Therefore artificial active lines are presently utilized The topology and two-port parameter requirements of the iterative two port are discussed. Future advances in solid-state electronics and thin-film technology should overcome this difficulty. Several current research studies involving semiconductor bulk effects and solid-state traveling-wave amplifiers are cited. Although this thesis is concerned with the class of active distributed network having an active transmission line equivalent, the various considerations are readily extendable to networks having other differential models. more generally then, this investigation is concerned with developing methods for analyzing and synthesizing active distributed networks

Enabling Technology in Optical Fiber Communications: From Device, System to Networking

This book explores the enabling technology in optical fiber communications. It focuses on the state-of-the-art advances from fundamental theories, devices, and subsystems to networking applications as well as future perspectives of optical fiber communications. The topics cover include integrated photonics, fiber optics, fiber and free-space optical communications, and optical networking

Aeronautical engineering: A continuing bibliography with indexes (supplement 211)

A continuing bibliography (NASA SP-7037) lists 519 reports, journal articles and other documents originally announced in February 1987 in Scientific and Technical Aerospace Reports (STAR) or in the International Aerospace Abstracts (IAA). The coverage includes documents on the engineering and theoretical aspect of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and associated components, equipment, and systems. It also includes research and development in aerodynamics, aeronautics, and ground support equipment for aeronautical vehicles. Each entry in the bibliography consists of a standard bibliographic citation accompanied in most cases by an abstract. The listing of the entries is arranged by the first nine STAR specific categories and the remaining STAR major categories. The arrangement offers the user the most advantageous breakdown for individual objectives. The citations include the original accession numbers from the respective announcement journals. The IAA items will precede the STAR items within each category. Seven indexes entitled subject, personal author, corporate source, foreign technology, contract number, report number, and accession number are included

Advances in Vibration Analysis Research

Vibrations are extremely important in all areas of human activities, for all sciences, technologies and industrial applications. Sometimes these Vibrations are useful but other times they are undesirable. In any case, understanding and analysis of vibrations are crucial. This book reports on the state of the art research and development findings on this very broad matter through 22 original and innovative research studies exhibiting various investigation directions. The present book is a result of contributions of experts from international scientific community working in different aspects of vibration analysis. The text is addressed not only to researchers, but also to professional engineers, students and other experts in a variety of disciplines, both academic and industrial seeking to gain a better understanding of what has been done in the field recently, and what kind of open problems are in this area

Ground vibration from underground railways: how simplifying assumptions limit prediction accuracy

Noise and vibration from underground railways is a documented disturbance to individuals living or working near subways. Much work has been done to understand and simulate the dynamic interactions between the train, track, tunnel and soil resulting in numerical models which can predict ground-borne vibration around the tunnels and at the soil surface. However, all such numerical models rely on simplifying assumptions to make the problems trackable: soil is assumed homogenous, tunnels are assumed long and straight, the soil is assumed to be in perfect contact with the tunnel, etc. This dissertation is concerned with quantifying the uncertainty associated with some of these simplifying assumptions to provide a better estimation of the prediction accuracy when numerical models are used for "real world" applications. The first section investigates the effect of voids at the tunnel-soil interface. The Pipe-in-Pipe model is extended to allow finite-sized voids at the interface by deriving the discrete transfer functions for the tunnel and soil from the continuous solution. The results suggest that relatively small voids can significantly affect the rms velocity predictions at higher frequencies (100-200Hz) and moderately effect predictions at lower frequencies (15-100Hz). The results are also found to be sensitive to void length and void sector angle. The second section investigates issues associated with assuming the soil is homogeneous: the effect of inclined soil layers; the effect of a subsiding soil layer; the effect of soil inhomogeneity. The thin-layer method approach is utilized as its semi-analytical formulation allows for accurate predictions with relatively short run times. The results from the three investigations suggest that slight inclination of soil layers and typical levels of soil inhomogeneity can result in significant variation in surface results compared to the homogeneous assumption. The geometric effect of a subsiding soil layer has a less significant effect on surface vibration. The findings from this study suggest that employing simplifying assumptions for the cases investigated can reasonably result in uncertainty bands of +/-5dB. Considering all the simplifying assumptions used in numerical models of ground vibration from underground railways it would not be unreasonable to conclude that the prediction accuracy for such a model may be limited to +/-10dB