Engineering Commons^™

Simulations Of Pulse Signals With X-Parameters, Nick K.H. Huang, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Nonlinearity is becoming increasingly important to IC technologies. From the PHD formalism, X-parameter models provide an accurate frequency-domain method under large-signal operating points to characterize their nonlinear behaviors. In this work, X-parameter models are investigated to handle time-domain pulse signals which is critical to IC signal integrity but was not studied before. Two representative circuits, an analog LNA and a digital CMOS buffer, were employed to characterize the X-parameter performance. The results obtained in this paper provide the first hand data for pulse signal responses of X-parameters in signal integrity modelings. © 2011 IEEE.

Work In Progress - Exercises In Squeak Smalltalk For Pre-College Education, Steve Eugene Watkins, Nicolette Kowalewski, Kathryn N. Rodhouse, Benjamin Cooper

Electrical and Computer Engineering Faculty Research & Creative Works

Computer programming education helps to prepare pre-college students to function in a technology-based society and to promote technical careers. However, opportunities are limited for pre-college students to learn computer programming and effective programming instruction can be difficult. A set of introductory, self-paced tutorials in Squeak Smalltalk has been developed for students in high school and middle school. This work describes two supplementary exercises that address the needs of new learners, especially those at younger ages. Students are given tools for drawing and image manipulation. The optional exercises integrate basic concepts while allowing more interactivity and customization through creative "play." © …

Work In Progress - Virtual Facilitation And Procedural Knowledge Education, Ray Luechtefeld, Steve Eugene Watkins

Electrical and Computer Engineering Faculty Research & Creative Works

Engineering students acquire both conceptual and procedural knowledge as part of their education. While conceptual knowledge, such as understanding why certain design practices are required or having knowledge of the general principles of engineering development, is essential, procedural knowledge to enact specific engineering practices is also needed. This kind of knowledge, such as balancing chemical equations, solving calculus problems, or finding Thevenin-Norton equivalents, is usually taught through rote problem solving, sometimes with the guidance of teaching assistants or aid from the instructor if students find themselves "stuck". However, a Virtual Facilitator, designed to help students develop team skills, can also …

Compact Metallic Rfid Tag Antennas With A Loop-Fed Method, Peng H. Yang, Yan Li, Lijun Jiang, W. C. Chew, Terry Tao Ye

Electrical and Computer Engineering Faculty Research & Creative Works

Several compact, low profile and metal-attachable RFID tag antennas with a loop-fed method are proposed for UHF RFID systems. The structure of the proposed antennas comprise of two parts: (1) The radiator part consists of two shorted patches, which can be treated as two quarter-wave patch antennas or a cavity. (2) A small loop printed on the paper serves as the feeding structure. The small loop provides the needed inductance for the tag and is connected to the RFID chip. The input impedance of the antenna can be easily adjusted by changing loop dimensions. The antenna has the compact size …

Mixed Integral-Differential Skin-Effect Models For Peec Electromagnetic Solver, Giulio Antonini, Albert E. Ruehli, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Efficient modeling of the broadband skin-effect for conducting 3D shapes is a challenging issue for the solution of large electromagnetic problems. The inclusion of such models in an EM solver can be very costly in compute time and memory requirements. Several properties of a model are desirable for the solution of practical problems such as the broadband frequency domain or the time domain applicability. In this paper, we present a model which meets some of these challenges and which is suitable for the PEEC solution method. © 2011 IEEE.

A Low Frequency Stable Epa Method Accelerated By The Adaptive Cross Approximation Algorithm, Zu Hui Ma, Lijun Jiang, Zhi Guo Qian, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Low frequency full wave electromagnetic modeling is of great importance to a number of applications. But it is also a great challenge in the research of computational electromagnetics (CEM). To address this issue, in this paper, we will discuss incorporating the augmented electric field integral equation (A-EFIE) into the low frequency augmented equivalence principle algorithm (A-EPA) method. It effectively improves the low frequency simulation stability. But this method involves the calculation of the translation process which is exceptionally time-consuming and memory-consuming. In order to surmount this problem, we use the adaptive cross approximation (ACA) to accelerate the calculation of this …

Modeling Electrically Small Structures In Layered Medium With Augmented Efie Method, Yongpin P. Chen, Lijun Jiang, Zhi Guo Qian, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

Electrically small structures embedded in a planarly layered medium are modeled by the augmented electric field integral equation (EFIE) method in this paper. By separating charge as extra unknown list, and enforcing the current continuity equation, an augmented EFIE (A-EFIE) can be setup. The matrix-friendly formulation of layered medium Green's function is applied and the frequency scaling of the impedance matrix in the moment method is analyzed when the frequency tends to zero. Rank deficiency and the charge neutrality enforcement is also discussed in detail. Numerical results show that the low frequency breakdown of electrically small structures embedded in a …

Finite-Width Gap Excitation And Impedance Models, Yat Hei Lo, Shiquan He, Lijun Jiang, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we present a new method for the feed model for the method of moments (MoM). It is derived from a more accurate model with the realistic size of the excitation, in order to replace the commonly-used delta-gap excitation model. This new model is formulated around the electric field integration equations (EFIE) where the terms for magnetic current and magnetic field can be removed. Hence it is much simpler to implement and reduces the numerical complexity. In addition, a variational formulation is derived to provide second order accuracy of the input admittance calculation. Moreover, this new formulation can …

Finite Element Based Generalized Impedance Boundary Condition For Complicated Em Calculation, Shiquan He, Zaiping Nie, Jun Zh Huang, Lijun Jiang, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a finite element based generalized impedance boundary condition (FEM-GIBC) is proposed to solve complicated electromagnetic (EM) problems. Complex structures with arbitrary inhomogeneity and shapes are modeled with the finite element method, and their scattering contributions are transformed to generalized impedance conditions on their boundaries. For each sub-domain, a special GIBC can be established and it is only related to the structures in this domain. Hence, for finite periodic structures, a representative GIBC can be formulated at the boundary of a unit cell. After the GIBC at each boundary is established, the electromagnetic coupling between each impedance boundary …

A New Closed-Form Evaluation Of Layered Medium Green's Function, Yongpin P. Chen, Weng Cho Chew, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A new closed-form evaluation of layered medium Green's function is proposed in this paper. The discrete complex image method (DCIM) is extended to sampling along the Sommerfeld branch cut, to capture the far field interaction. Contour deformation technique is applied to decompose the Green's function into radiation modes (branch cut integration) and guided modes (surface-wave poles). The matrix pencil method is implemented to get a closed-form solution, with the help of an alternative Sommerfeld identity. Numerical results are presented to demonstrate the accuracy of this method. © 2011 IEEE.

Reflection And Transmission Of Line-Source Excited Pulsed Em Fields At A Thin, High-Contrast Layer With Dielectric And Conductive Properties, Adrianus T. De Hoop, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A methodology is presented for analytically modeling the reflection and transmission of line-source excited pulsed electromagnetic fields fields at a thin, planar, high-contrast layer with dielectric and conductive properties. Closed-form time-domain expressions are derived for the field components in a two-dimensional setting via an extension of the Cagniard-DeHoop method. © 2011 IEEE.

Full-Wave Emc Simulations Using Maxwell Garnett Model For Composites With Cylindrical Inclusions, M. H. Nisanci, F. De Paulis, Marina Koledintseva, A. Orlandi

Electrical and Computer Engineering Faculty Research & Creative Works

Four different models for effective dielectric properties of biphasic composite containing random or aligned cylindrical inclusions are considered in this paper. These models are based on the Maxwell Garnett (MG) mixing rule. The effects of distribution and orientation of cylindrical inclusions in a composite material is studied. An equivalent averaged material with Debye-like frequency characteristics, suitable for time-domain full-wave numerical electromagnetic simulations is retrieved. This Debye model is derived from the Maxwell Garnett formulation. The numerical model test structure consists of a composite slab inserted in a rectangular waveguide. Simulations are run for the frequency range above the cut-off frequency …

A Novel Characterization Method Of The Radiation Emission For Electromagnetic Compatibility, Ping Li, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Conventionally the radiation emissions from PCB boards, electronic devices and antennas were characterized through the near field (NF)-far field (FF) transformation to find the equivalent sources. In this paper, a new methodology without NF-FF transformation is presented. Based on the uniqueness theorem, it only employs the measured tangential field over a spherical surface to rigorously characterize the outward radiation emission. The dyadic Green's function for the perfect magnetic conductor (PMC) sphere is derived using spherical wave functions. Based on this dyadic Green's function and integral equations, the NF-FF transformation is not necessary any more. To facilitate feasible near field measurements, …

High Frequency Permeability Of Fe-Al-Si Granular Composite Materials, Takanori Tsutaoka, Taisuke Ono, Aiko Tsurunaga, Teruhiro Kasagi, Kenichi Hatakeyama, Marina Koledintseva

Electrical and Computer Engineering Faculty Research & Creative Works

High-frequency electromagnetic properties of Fe-Al-Si alloy (Sendust) granular composite materials have been studied by measuring their relative complex permeability (μ_r = μ_r’ – jμ_r”) and permittivity (ε_r = ε_r’ – j ε_r”) spectra. The bulk Fe-Al-Si alloy shows metallic electrical conduction, and permeability decreases rapidly with frequency. On the other hand, Sendust powder shows relatively high electrical resistivity. Sendust composite material demonstrates insulating electrical properties up to at least 80 vol.% particle content. Thus the relatively high permeability in the microwave frequency range can be obtained. Frequency dispersion characteristics of …

Electron Transport Through Two Irreducibly-Coupled Aharonov-Bohm Rings With Applications To Nanostructure Quantum Computing Circuits, C. A. Cain, Cheng-Hsiao Wu

Electrical and Computer Engineering Faculty Research & Creative Works

We investigated several classes of two coupled Aharonov-Bohm rings that share a finite center common path, where the phase of the electron wave function can be modulated by two distinct magnetic fluxes. The coupling is similar to two coupled atoms. The behavior of charge accumulation along the center common path or, equivalently, the bonding and anti-bonding of the two rings can be achieved as the two applied fluxes are varied. Thus, when three external terminals are connected to such coupled rings, the behavior of the electron transport is divided into several classes, depending on the number of atoms in each …

Coaxial Cable Bragg Grating, Tao Wei, Songping Wu, Jie Huang, Hai Xiao, Jun Fan

Electrical and Computer Engineering Faculty Research & Creative Works

This paper reports a coaxial cable Bragg grating (CCBG) fabricated by drilling holes into the cable at periodic distances along the axial direction. Resonances were observed at discrete frequencies in both transmission and reflection spectra. The analogy of the CCBG with a fiber Bragg grating is shown. The grating was tested for the potential application as a strain-sensing device.

Process-Variation-Aware Electromagnetic-Semiconductor Coupled Simulation, Yuanzhe Xu, Quan Chen, Lijun Jiang, Ngai Wong

Electrical and Computer Engineering Faculty Research & Creative Works

We develop a new method based on the high-frequency electromagnetic (EM)-semiconductor coupled simulation to analyze the impact of multi-type process variations happen around semi-conductormetal structure. It is competent to simultaneously handle geometrical variations like surface roughness and material variations like semi-conductor doping profile, which are difficult for traditional stand alone simulation methods. A sparse grid based stochastic spectral collocation method (SSCM) combined with principle factor analysis (PFA) is implemented to accelerate the stochastic simulation. Numerical results confirm the validity and significance of our variational coupled simulation framework. © 2011 IEEE.

Attenuation In Extended Structures Coated With Thin Magneto-Dielectric Absorber Layer, Marina Koledintseva, Alexander G. Razmadze, Aleksandr Yakubovich Gafarov, Victor Khilkevich, James L. Drewniak, Takanori Tsutaoka

Electrical and Computer Engineering Faculty Research & Creative Works

Thin absorbing layers containing magnetic alloy or ferrite inclusions can be effectively used for attenuating common-mode currents on extended structures, such as power cords, cables, or edge-coupled microstrip lines. An analytical model to evaluate attenuation on the coaxial line with the central conductor coated with a magneto-dielectric layer is proposed and validated by the experiments and numerical modeling. The analytical model is validated using available magneto-dielectric samples of different thicknesses. This model can serve for comparing and predicting the absorptive properties of different samples of magneto-dielectric materials, whose compositions may be unknown, but dielectric and magnetic properties can be determined …

A Novel Implementation Of Discrete Complex Image Method For Layered Medium Green's Function, Yongpin P. Chen, Weng Cho Chew, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A novel implementation of discrete complex image method (DCIM) based on the Sommmerfeld branch cut is proposed to accurately capture the far-field behavior of the layered medium Green's function as a complement to the traditional DCIM. By contour deformation, the Green's function can be naturally decomposed into branch-cut integration (radiation modes) and pole contributions (guided modes). For branch-cut integration, matrix pencil method is applied, and the alternative Sommerfeld identity in terms of kz integration is utilized to get a closed-form solution. The guided modes are accounted for with a pole-searching algorithm. Both one-branch-cut and two-branch-cut cases are studied. Several numerical …

An Augmented Electric Field Integral Equation For Layered Medium Green's Function, Yongpin P. Chen, Lijun Jiang, Zhi Guo Qian, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes an augmented electric field integral equation (A-EFIE) for layered medium Green's function. The newly developed matrix-friendly formulation of layered medium Green's function is applied in this method. By separating charge as extra unknown list, and enforcing the current continuity equation, the traditional EFIE can be cast into a generalized saddle-point system. Frequency scaling for the matrix-friendly formulation is analyzed when frequency tends to zero. Rank deficiency and the charge neutrality enforcement of the A-EFIE for layered medium Green's function is discussed in detail. The electrostatic limit of the A-EFIE is also analyzed. Without any topological loop-searching algorithm, …

Apparatus For Converting Direct Current To Alternating Current Using Multiple Converters, Patrick L. Chapman, Brian T. Kuhn, Robert S. Balog, Jonathan W. Kimball, Philip T. Krein, Alexander Gray, T. Esram

Electrical and Computer Engineering Faculty Research & Creative Works

An inverter for converting an input direct current (DC) waveform from a DC source to an output alternating current (AC) waveform for delivery to an AC grid includes an input converter, an output converter, and an active filter, each of which is electrically coupled to a bus. The bus may be a DC bus or an AC bus. The input converter is configured to convert the input DC waveform to a DC or AC bus waveform. The output converter is configured to convert the bus waveform to the output AC waveform at a grid frequency. The active filter is configured …

Nanostructured Substrate With Nanoparticles Fabricated By Femtosecond Laser For Surface-Enhanced Raman Scattering, Yukun Han, Zhi Liang, Huilai Sun, Hai Xiao, Hai-Lung Tsai

Electrical and Computer Engineering Faculty Research & Creative Works

A Simple and Fast Method to Fabricate Nanostructured Substrates with Silver Nanoparticles over a Large Area for Surface-Enhanced Raman Scattering (SERS) is Reported. the Method Involves Two Steps: (1) Dip the Substrate into a Silver Nitrate Solution for a Few Minutes, Remove the Substrate from the Solution, and Then Air Dry and (2) Process the Silver Nitrate Coated Substrate by Femtosecond (Fs) Laser Pulses in Air. the Second Step Can Create Silver Nanoparticles Distributed on the Nanostructured Surface of the Substrate by the Photoreduction of Fs Multiphoton Effects. This Study Demonstrates that an Enhancement Factor (EF) Greater Than 5x105, Measured …

Multilayer Network Resilience Analysis And Experimentation On Geni, Justin P. Rohrer, Egemen K. Çetinkaya, James P. G. Sterbenz

Electrical and Computer Engineering Faculty Research & Creative Works

GENI is evolving to provide a promising environment in which to do experimental research in the resilience and survivability of future networks, by allowing programmable control over topology and mechanism, while providing the scale and global reach needed to conduct network experiments far beyond the capabilities of a conventional testbed. We will use GENI in general, and the GpENI infrastructure (expanding to 40 clusters with 200 nodes worldwide), federated with the larger GENI PlanetLab control framework and interconnected to several ProtoGENI facilities to perform resilience and survivability experiments at scale, both in terms of node count and with the geographic …

Reducing Dimensionality Of Hyperspectral Data With Diffusion Maps And Clustering With K-Means And Fuzzy Art, Louis Du Plessis, Rui Xu, Steven Damelin, Michael Sears, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

It is very difficult to analyse large amounts of hyperspectral data. Here we present a method based on reducing the dimensionality of the data and clustering the result in moving toward classification of the data. Dimensionality reduction is done with diffusion maps, which interpret the eigenfunctions of Markov matrices as a system of coordinates on the original dataset in order to obtain an efficient representation of data geometric descriptions. Clustering is done using k-means and a neural network clustering theory, Fuzzy ART (FA). The process is done on a subset of core data from AngloGold Ashanti, and compared to results …

Design Of A Conditioner For Smoothing Wind Turbine Output Power, Murali Bottu

Masters Theses

"As a result of wind speed intermittency, wind turbine output power can be highly variable. The large variability in output power can adversely impact local loads that are sensitive to pulsating power. To mitigate large swings in power, the wind turbine output power can be smoothed by using a small energy buffer. A power conditioner is proposed to smooth the wind power output by utilizing the energy of an ultracapacitor. The conditioner is based on a single phase voltage source inverter (VSI) connected between the grid interconnection point and the ultracapacitor. The shunt VSI injects or absorbs active power from …

Towards On-Line Voltage Stability Assessment Using Synchrophasors, Himanshu Subandhu Hirlekar

Masters Theses

"Voltage instability has become a growing concern in the operation of power systems in recent years. The reason is that power systems all over are being operated with reduced margins because of increased demand exacerbated by a general reluctance to invest in improvement of the electric grid infrastructure. Until recently it was difficult to predict voltage instability in the on-line environment. However, advances in technology has made possible the on-line monitoring and assessment of voltage stability. Synchrophasors is a relatively new technology in the field of power systems which allows system operators to monitor the system conditions at specific measurement …

Development Of A Fuel Cell Plug-In Hybrid Electric Vehicle And Vehicle Simulator For Energy Management Assessment, Andrew Meintz

Doctoral Dissertations

"This dissertation offers a description of the development of a fuel cell plug-in hybrid electric vehicle focusing on the propulsion architecture selection, propulsion system control, and high-level energy management. Two energy management techniques have been developed and implemented for real-time control of the vehicle. The first method is a heuristic method that relies on a short-term moving average of the vehicle power requirements. The second method utilizes an affine function of the short-term and long-term moving average vehicle power requirements. The development process of these methods has required the creation of a vehicle simulator capable of estimating the effect of …

Rapid Simulation Of The Statistical Variation Of Crosstalk In Cable Harness Bundles, Xiang Li

Masters Theses

"Accurate assessment of crosstalk problems in cable harnesses requires simulation methods that account for the statistical variation of harness parameters. Methods are proposed to determine the influence of the statistical variation in wire positions, the rate that wires change position (i.e. "twist"), harness height, harness density (i.e. how closely wires are packed) and circuit loads. Methods use a combination of simulation and probability theory. Simulations use the T-parameter method, a rapid simulation technique for harness bundles. Simulation time is further improved by using the mean and variance of crosstalk estimated for fixed harness parameter values to estimate the mean and …

Impact Of Channel Statistics And Correlation On Underwater Acoustic Communication Systems, Jesse Scott Cross

Masters Theses

"Several statistical properties of underwater acoustic channels gathered from experiment data are analyzed. The baseband channel impulse response (CIR) is estimated using a time domain least squares technique with a sliding window applied to the probing sequences. From the CIR estimation, the probability distribution functions (PDFs) of the magnitude, real part, imaginary part, and phase of the CIR are calculated. Gamma, Rayleigh, and compound k distributions are fitted to the magnitude PDF and the fitness of the distributions are calculated with a two-sample Kolmogorov-Smirnov test. Other statistics such as the autocorrelation function, coherence time, and scattering function are evaluated. The …

Simulink As A Tool For Modelling Communication Systems, Chaitri Avinash Aroskar

Masters Theses

"Simulink is a graphical tool provided by MathWorks to enable model-based design and simulation. This thesis consists of two papers which take advantage of Simulink features in order to model communication systems.

The first paper employs Simulink to create projects to supplement a purely lecture oriented course: Communication Systems I. The projects cover Linear systems, Analog modulation and Digital modulation concepts in a set of six projects. These projects have been designed based on Gagne's nine events of instruction to enhance their impact on students' learning process. The paper also outlines the advantages of this approach over the conventional programming …