Regularized maxwell equations and nodal finite elements for electromagnetic field computations in frequency domain

In this work we present an alternative approach to the usual finite element formulation based on edge elements and double-curl Maxwell equations. This alternative approach is based on nodal elements and regularized Maxwell equations. The advantages are that, without adding extra unknowns (such as Lagrange multipliers), it provides spurious-free solutions and well-conditioned matrices. Besides, its integral representation involves a less singular kernel (order 1 instead of 3), which makes this approach best suited to hybridization with integral numerical techniques. On the other hand, a new set of difficulties arises that were not present in the classical formulation. The main drawback is that a globally wrong solution is obtained when the electromagnetic field has a singularity in the problem domain. Also, boundary conditions and field discontinuities are more laborious to implement. This work explains how to overcome these difficulties and demonstrates that accurate solutions can be obtained with nodal elements and the regularized formulation. We also present ERMES, the C++ implementation of the finite element approach depicted above and the main deliverable of this work. We compute with ERMES the scattering parameters of microwave filters and the specific absorption rate induced in a body when exposed to electromagnetic fields. ERMES is also the computational tool used in two novel numerical models introduced in this work. The first one characterizes electromagnetic metal forming processes and the second one the transfer impedance of cable shields. The electromagnetic metal forming model calculates the driving Lorentz force and estimates the optimum frequency at which it is attained the maximum workpiece deformation. The main advantage of the approach is that it provides an explicit relation between the capacitance of the capacitor bank and the frequency of the discharge, which is a key parameter in the design of an electromagnetic forming system. The successful application of the regularized formulation in this model reveals its excellent behavior in the low-frequency (quasi-static) regime. The second numerical model introduced in this work computes the transfer impedance of cable shields. The model reproduces the high frequency behavior of the transfer impedance more accurately than the approaches found in the literature and, moreover, it is able to analyze a wider variety of geometries and materials

An investigation on the resonance observed in a spirally shielded twinaxial differential pair

Spirally shielded twinaxial cable assemblies are extensively used in multi-gigabit-per-second digital telecommunications systems. Unlike ideally shielded Twinaxial cables, spirally shielded cables exhibit resonant behavior which limits system throughput. This body of work illustrates a predictive method for determining resonant behavior in twinaxial cables through physical measurement of commercially available cables and analogous transmission line fixtures, full-wave and quasi-static simulations, and equivalent circuit analysis. It will be shown that frequency dependent standing wave resonances in twinaxial cables are independent of cable length and dependent on cross-sectional feature sizes, dielectric properties, and spiral shield pitch

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

Contribution to the study of the vulnerability of critical systems to Intentional Electromagnetic Interference (IEMI)

The progress of high power electromagnetic (HPEM) sources during the late 1990s raised the concern in the electromagnetic compatibility (EMC) community that they could be deployed for criminal purposes to interfere with the operation of modern electronic systems. It is well established that sufficiently intense electromagnetic fields can cause upset or damage in electronic systems and therefore, can affect almost every critical infrastructure (CI) that is based on information and communication technologies (ICT). This field of study was initially known as electromagnetic terrorism, but was changed to the more encompassing term of intentional electromagnetic interference (IEMI). This thesis is a contribution to the assessment techniques of the vulnerability of CIs against IEMI. In order to quantify their impact, the electromagnetic environment created by IEMI sources needs to be characterized, the susceptible components and subsystems of the CIs should be identified, and the expected disturbances have to be evaluated. We present a qualitative methodology to carry out the so-called IEMI audit of a facility. Given the complexity of the problem, it was decided that the vulnerability of an infrastructure should be evaluated in a qualitative manner by regarding the consequences of interrupting the normal provision of a service, the probability of occurrence of an IEMI attack, and the preparedness of the infrastructure to withstand an attack. An updated survey and classification of potential IEMI sources that were collected from a large number of scientific publications is presented. The sources have been classified according to their electromagnetic environment, their transportability, technological development, and cost level. The expected disturbances due to a high frequency illumination of representative cabling systems inside an office were studied through measurements performed using a plastic raceway containing several types of cables found in commercial buildings. The tests revealed that at low and intermediate frequencies, low voltage power cables are more susceptible compared to telephone or network cables. At high frequencies, the coupling is dominated by connector apertures and discontinuities and load unbalance. The applicability of the TL theory in evaluating differential mode signals in two-wire lines floating above a ground plane was studied through comparisons with full-wave simulations. The results showed that the validity of the TL theory is conditioned upon an electrically short distance between the differential wires, regardless of the distances above the ground plane. TL theory is also used to assess the effect of conductive and dielectric losses in the dispersion of injected IEMI signals along power and communication cables as a function of the propagation length. A TL model of the low voltage power cabling of the plastic raceway was developed and in order to validate the models, the numerical results were compared against measurements obtained using frequency and time domain techniques. General considerations and guidelines for the application of the TL theory for evaluating the overall transfer impedance of complex cable assemblies are given. The obtained simulation results were found to be in good agreement with the experimental data up to frequencies of about 500 MHz. Finally, an improved model for estimating the transfer impedance of a two-layer braided shield is also proposed and validated using experimental data

Cable discharge events (CDE) -- A modeling and simulation perspective

Cable discharge events (CDE) typically occur when a charged cable is connected to an electronic device. Several CDE damages in Ethernet LAN and USB communication interface equipment are reported by the IC manufacturers. CDE differs from other types of ESD such as human body model (HBM), charged device model (CDM) and IEC 61000-4-2 mainly due to faster rise times, longer pulse widths and higher peak currents. Various factors such as cable geometries, charging and discharging mechanisms, and load conditions influence CDE. Several researchers have developed some measurement techniques to understand CDE waveforms. However, there is little information regarding its modeling and simulation. This study mainly focuses on developing simulation models for Cable Discharge Events (CDE) in general and specific to Ethernet LAN interfaces. An overview of some of the most relevant publications is provided at first, to understand the current state-of-the-art. Further, the factors that influence CDE are explained in detail. Next, various CDE modeling and simulation approaches are compared and two modeling techniques to simulate some of the most important aspects of CDE are proposed. The first method mainly deals with the estimation of voltages on conductors during charging and discharging. The second method, a hybrid modeling technique, aims at simulating the CDE of an unshielded twisted pair (UTP) with reasonable accuracy and simulation time. The details of a simple CDE tester that was developed to validate the simulation model are explained. Several factors that affect CDE such as cable length, cable\u27s height above a ground plane, discharge sequencing, presence of a vertical discharge plane etc. are analyzed using the proposed simulation techniques. At the end, all major simulation results are discussed and the scope of future work is also mentioned --Abstract, page iii

JefiGPU: Jefimenko's Equations on GPU

We have implemented a GPU version of the Jefimenko's equations -- JefiGPU. Given the proper distributions of the source terms $\rho$ (charge density) and $\mathbf{J}$ (current density) in the source volume, the algorithm gives the electromagnetic fields in the observational region (not necessarily overlaps the vicinity of the sources). To verify the accuracy of the GPU implementation, we have compared the obtained results with that of the theoretical ones. Our results show that the deviations of the GPU results from the theoretical ones are around 5\%. Meanwhile, we have also compared the performance of the GPU implementation with a CPU version. The simulation results indicate that the GPU code is significantly faster than the CPU version. Finally, we have studied the parameter dependence of the execution time and memory consumption on one NVIDIA Tesla V100 card. Our code can be consistently coupled to RBG (Relativistic Boltzmann equations on GPUs) and many other GPU-based algorithms in physics.Comment: 21 pages, 8 figures, 4 table

Avionics system design for high energy fields: A guide for the designer and airworthiness specialist

Because of the significant differences in transient susceptibility, the use of digital electronics in flight critical systems, and the reduced shielding effects of composite materials, there is a definite need to define pracitices which will minimize electromagnetic susceptibility, to investigate the operational environment, and to develop appropriate testing methods for flight critical systems. The design practices which will lead to reduced electromagnetic susceptibility of avionics systems in high energy fields is described. The levels of emission that can be anticipated from generic digital devices. It is assumed that as data processing equipment becomes an ever larger part of the avionics package, the construction methods of the data processing industry will increasingly carry over into aircraft. In Appendix 1 tentative revisions to RTCA DO-160B, Environmental Conditions and Test Procedures for Airborne Equipment, are presented. These revisions are intended to safeguard flight critical systems from the effects of high energy electromagnetic fields. A very extensive and useful bibliography on both electromagnetic compatibility and avionics issues is included

Lightning protection of aircraft

The current knowledge concerning potential lightning effects on aircraft and the means that are available to designers and operators to protect against these effects are summarized. The increased use of nonmetallic materials in the structure of aircraft and the constant trend toward using electronic equipment to handle flight-critical control and navigation functions have served as impetus for this study

Aircraft electromagnetic compatibility

Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting