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Electrical and Computer Engineering Faculty Research & Creative Works

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Articles 1561 - 1590 of 3518

Full-Text Articles in Engineering

Soft-Decision Feedback Turbo Equalization For Multilevel Modulations, Huang Lou, Chengshan Xiao Dec 2011

Soft-Decision Feedback Turbo Equalization For Multilevel Modulations, Huang Lou, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

Error propagation phenomena is the major drawback for existing hard-decision feedback turbo equalizers. in this paper, we propose a new soft-decision feedback equalizer (SDFE) suitable for multilevel modulation systems employing turbo equalization. the proposed SDFE offers a low computational complexity growing only linearly with the number of equalizer coefficients, as opposed to the quadratic complexity of MMSE-Based linear turbo equalizer with time-varying coefficients (Exact-MMSE-LE). the performance and convergence property of the proposed SDFE are analyzed using extrinsic information transfer (EXIT) chart and verified by simulations in a severe InterSymbol interference channel set by Proakis. Results show that our approach performs …

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3d Image Reconstruction From Sparse Measurement Of Wideband Millimeter Wave Sar Experiments, Hamed Kajbaf, Joseph T. Case, Yahong Rosa Zheng Dec 2011

3d Image Reconstruction From Sparse Measurement Of Wideband Millimeter Wave Sar Experiments, Hamed Kajbaf, Joseph T. Case, Yahong Rosa Zheng

Electrical and Computer Engineering Faculty Research & Creative Works

Nonuniform random sampling is applied to a wideband 3D synthetic aperture radar (SAR) imaging system to reduce the number of measurement points in both frequency and space domains. Experimental tests were performed on a construction foam specimen using uniformly sampled Q-band frequencies in 35.04 GHz to 44.96 GHz and at a grid of two-millimeter step sizes. using discrete Fourier transform (DFT) or discrete cosine transform (DCT) sparse representations, the 3D images can be reconstructed from 7% random samples of the experimental data achieving comparable quality as the one from original full-set data. This can translate to significant time reduction of …

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Mahalanobis-Taguchi System As A Multi-Sensor Based Decision Making Prognostics Tool For Centrifugal Pump Failures, Ahmet Soylemezoglu, Sarangapani Jagannathan, Can Saygin Dec 2011

Mahalanobis-Taguchi System As A Multi-Sensor Based Decision Making Prognostics Tool For Centrifugal Pump Failures, Ahmet Soylemezoglu, Sarangapani Jagannathan, Can Saygin

Electrical and Computer Engineering Faculty Research & Creative Works

A novel Mahalanobis Taguchi System (MTS) based fault detection, isolation, and prognostics scheme is presented. the proposed scheme fuses data from multiple sensors into a single system level performance metric using Mahalanobis Distance (MD) and generates fault clusters based on MD values. MD thresholds derived from the clustering analysis are used for fault detection and isolation. When a fault is detected, the prognostics scheme, which monitors the progression of the MD values over time, is initiated. Then, using a linear approximation, time to failure is estimated. the performance of the scheme has been validated via experiments performed on a mono-block …

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Work In Progress - Exercises In Squeak Smalltalk For Pre-College Education, Steve Eugene Watkins, Nicolette Kowalewski, Kathryn N. Rodhouse, Benjamin Cooper Dec 2011

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." © …

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Comparison Of A Recurrent Neural Network Pv System Model With A Traditional Component-Based Pv System Model, Daniel M. Riley, Ganesh K. Venayagamoorthy Dec 2011

Comparison Of A Recurrent Neural Network Pv System Model With A Traditional Component-Based Pv System Model, Daniel M. Riley, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

Photovoltaic (PV) system modeling is used throughout the photovoltaic industry for the prediction of PV system output under a given set of weather conditions. PV system modeling has a wide range of uses including pre-purchase comparisons of PV system components, system health monitoring, and estimation of payback (return on investment) times. in order to adequately model a PV system, the system must be characterized to establish the relationship between given weather inputs (e.g., irradiance, spectrum, temperature) and desired system outputs (e.g., AC power, module temperature). Traditional approaches to system characterization involve characterizing and modeling each component in a PV system …

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Mixed Integral-Differential Skin-Effect Models For Peec Electromagnetic Solver, Giulio Antonini, Albert E. Ruehli, Lijun Jiang Dec 2011

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.

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Validation Of The Triply Selective Fading Channel Model Through A Mimo Test Bed And Experimental Results, Saurav Subedi, Huang Lou, Fei Ren, Mingxi Wang, Y. Rosa Zheng Dec 2011

Validation Of The Triply Selective Fading Channel Model Through A Mimo Test Bed And Experimental Results, Saurav Subedi, Huang Lou, Fei Ren, Mingxi Wang, Y. Rosa Zheng

Electrical and Computer Engineering Faculty Research & Creative Works

Multiple-input multiple-output (MIMO) channel is often triply selective, meaning that it has spatial, temporal and inter-tap correlation. the temporal correlation is well characterized by its Doppler spectrum, but spatial and inter-tap correlation and their impact on MIMO channels are less studied in the literature. a MIMO testbed has been established to measure the impulse response of MIMO channels and an estimation method is developed to quantitatively measure the correlation matrices from experimental data. © 2011 IEEE.

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A Comparison Of Bss Algorithms In Harsh Environments, Christopher Osterwise, Steven Grant Nov 2011

A Comparison Of Bss Algorithms In Harsh Environments, Christopher Osterwise, Steven Grant

Electrical and Computer Engineering Faculty Research & Creative Works

This paper compares the performance of several blind source separation (BSS) algorithms in environments of varying reverberation, noise, microphone spacing, and sparsity. of particular interest are two frequency domain algorithms: one Cascaded ICA with Intervention Alignment (CICAIA), and one algorithm by Pham, Servire, and Boumaraf. the former is found to work exceptionally well in high noise, low microphone spacing environments. the latter proves to work exceptionally well in high SNR and moderate- to widely spaced arrays. in addition, while the literature on BSS algorithms is extensive, their performance under varying noise conditions has not been widely explored. Also, though usually …

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Model-Free H∞ Stochastic Optimal Design For Unknown Linear Networked Control System Zero-Sum Games Via Q-Learning, Hao Xu, Sarangapani Jagannathan Nov 2011

Model-Free H∞ Stochastic Optimal Design For Unknown Linear Networked Control System Zero-Sum Games Via Q-Learning, Hao Xu, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, stochastic optimal strategy for unknown linear networked control system (NCS) quadratic zero-sum games related to H∞ optimal control in the presence of random delays and packet losses is solved in forward-in-time manner. This approach does not require the knowledge of the system matrices since it uses Q-learning. the proposed stochastic optimal control approach, referred as adaptive dynamic programming (ADP), involves solving the action dependent Q-function Q (z, u, d) of the zero-sum game instead of solving the state dependent value function J (z) which satisfies a corresponding Game Theoretic Riccati equation (GRE). an adaptive estimator (AE) is …

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Calibration And 3-D Sound Reproduction In The Immersive Audio Environment, Pratik Shah, Steven Grant, William Chapin Nov 2011

Calibration And 3-D Sound Reproduction In The Immersive Audio Environment, Pratik Shah, Steven Grant, William Chapin

Electrical and Computer Engineering Faculty Research & Creative Works

The effectiveness of virtual environments depends largely on how efficiently they recreate the real world. in the case of auditory virtual environments, the importance of accurate recreation is enhanced since there are no visual cues to assist perception, as in the case of audio-visual virtual environments. in this paper, we present the Immersive Audio Environment (IAE), an easily constructible and portable structure, which is capable of 3-D sound auralization with very high spatial resolution. a novel method for acoustically positioning loudspeakers in space, which is required by the IAE for simulation of sound sources, is presented in this paper. Our …

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Nn/Rise-Based Asymptotic Tracking Control Of Uncertain Nonlinear Systems, Qinmin Yang, Sarangapani Jagannathan, Youxian Sun Nov 2011

Nn/Rise-Based Asymptotic Tracking Control Of Uncertain Nonlinear Systems, Qinmin Yang, Sarangapani Jagannathan, Youxian Sun

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a novel control methodology for the tracking control of a high-order continuous time nonlinear systems with unknown dynamics and external disturbance. the control signal consists of the robust integral of the sign of the error (RISE) feedback signal multiplied with an adaptive gain plus neural network (NN) output. the two-layer NN learns the system dynamics in an online manner while residual reconstruction errors and the external bounded system disturbances are overcome by the RISE signal. Semi-global asymptotic tracking performance is theoretically guaranteed by using the Lyapunov standard method, while the NN weights and all other signals are …

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Artificial Immune System-Based Diagnostics And Prognostics Scheme And Its Experimental Verification, Gary R. Halligan, Balaje T. Thumati, S. Jagannathan Nov 2011

Artificial Immune System-Based Diagnostics And Prognostics Scheme And Its Experimental Verification, Gary R. Halligan, Balaje T. Thumati, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a novel fault diagnostics and prediction (FDP) scheme is introduced by using artificial immune system (AIS) as an online approximator for a class of nonlinear discrete-time systems. Traditionally, AIS is considered as an offline tool for fault detection (FD). However, in this paper, AIS is utilized as an online approximator in discrete time (OLAD) along with a robust adaptive term in the proposed fault diagnostics observer. using the fact that the system outputs are alone measurable, an output residual is determined by comparing the observer and system outputs and a fault is detected if this output residual …

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An Online Model-Based Fault Diagnosis Scheme For Hvac Systems, Balaje T. Thumati, Miles A. Feinstein, James W. Fonda, Alfred Turnbull, Fay J. Weaver, Mark E. Calkins, S. Jagannathan Nov 2011

An Online Model-Based Fault Diagnosis Scheme For Hvac Systems, Balaje T. Thumati, Miles A. Feinstein, James W. Fonda, Alfred Turnbull, Fay J. Weaver, Mark E. Calkins, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a model-based fault detection and isolation (FDI) scheme with online fault learning capabilities is proposed for HVAC systems. an observer comprising of an online approximator in discrete-time (OLAD) and a robust term is used for detection. a fault is detected if the generated detection residual, which is defined as the error between the observer outputs and HVAC system states, exceeds an apriori chosen threshold. the OLAD term in the FD observer learns the fault dynamics online while the robust term guarantees asymptotic estimation of the system states. Subsequent to detection, a fault isolation observer, which comprises of …

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A New Closed-Form Evaluation Of Layered Medium Green's Function, Yongpin P. Chen, Weng Cho Chew, Lijun Jiang Nov 2011

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.

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Modeling Electrically Small Structures In Layered Medium With Augmented Efie Method, Yongpin P. Chen, Lijun Jiang, Zhi Guo Qian, Weng Cho Chew Nov 2011

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 …

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Decentralized Optimal Control Of A Class Of Interconnected Nonlinear Discrete-Time Systems By Using Online Hamilton-Jacobi-Bellman Formulation, Shahab Mehraeen, Sarangapani Jagannathan Nov 2011

Decentralized Optimal Control Of A Class Of Interconnected Nonlinear Discrete-Time Systems By Using Online Hamilton-Jacobi-Bellman Formulation, Shahab Mehraeen, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the direct neural dynamic programming technique is utilized to solve the Hamilton-Jacobi-Bellman equation forward-in-time for the decentralized near optimal regulation of a class of nonlinear interconnected discrete-time systems with unknown internal subsystem and interconnection dynamics, while the input gain matrix is considered known. Even though the unknown interconnection terms are considered weak and functions of the entire state vector, the decentralized control is attempted under the assumption that only the local state vector is measurable. the decentralized nearly optimal controller design for each subsystem consists of two neural networks (NNs), an action NN that is aimed to …

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A Dynamic Programming Approach: Improving The Performance Of Wireless Networks, Sandeep Kolli, Maciej Zawodniok Nov 2011

A Dynamic Programming Approach: Improving The Performance Of Wireless Networks, Sandeep Kolli, Maciej Zawodniok

Electrical and Computer Engineering Faculty Research & Creative Works

Traditional wireless networks focus on transparent data transmission where the data are processed at either the source or destination nodes. in contrast, the proposed approach aims at distributing data processing among the nodes in the network thus providing a higher processing capability than a single device. Moreover, energy consumption is balanced in the proposed scheme since the energy intensive processing will be distributed among the nodes. the performance of a wireless network is dependent on a number of factors including the available energy, energy efficiency, data processing delay, transmission delay, routing decisions, security architecture etc. Typical existing distributed processing schemes …

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Linear Precoding For Mimo Multiple Access Channels With Finite Discrete Inputs, Mingxi Wang, Weiliang Zeng, Chengshan Xiao Nov 2011

Linear Precoding For Mimo Multiple Access Channels With Finite Discrete Inputs, Mingxi Wang, Weiliang Zeng, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we study linear precoding for multiple-input multiple-output (MIMO) multiple access channels (MAC) with finite discrete inputs. We derive the constellation-constrained capacity region for the MIMO MAC with an arbitrary number of users and find that the boundary can be achieved by solving the problem of weighted sum rate maximization with constellation and individual power constraints. Due to the non-concavity of the objective function, we obtain a set of necessary conditions for the optimization problem through Karush-Kuhn-Tucker analysis. to find the optimal precoding matrices for all users, we propose an iterative algorithm utilizing alternating optimization strategy. in particular, …

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A Low Frequency Stable Epa Method Accelerated By The Adaptive Cross Approximation Algorithm, Zu Hui Ma, Lijun Jiang, Zhi Guo Qian, Lijun Jiang Nov 2011

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 …

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Finite Element Based Generalized Impedance Boundary Condition For Complicated Em Calculation, Shiquan He, Zaiping Nie, Jun Zh Huang, Lijun Jiang, Weng Cho Chew Nov 2011

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 …

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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 Nov 2011

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.

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Finite-Width Gap Excitation And Impedance Models, Yat Hei Lo, Shiquan He, Lijun Jiang, Weng Cho Chew Nov 2011

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 …

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Full-Wave Emc Simulations Using Maxwell Garnett Model For Composites With Cylindrical Inclusions, M. H. Nisanci, F. De Paulis, Marina Koledintseva, A. Orlandi Oct 2011

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 …

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A Novel Characterization Method Of The Radiation Emission For Electromagnetic Compatibility, Ping Li, Lijun Jiang Oct 2011

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, …

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Multipoint Model Order Reduction Of Delayed Peec Systems, Francesco Ferranti, Michel Nakhla, Giulio Antonini, Tom Dhaene, Luc Knockaert, Albert E. Ruehli Oct 2011

Multipoint Model Order Reduction Of Delayed Peec Systems, Francesco Ferranti, Michel Nakhla, Giulio Antonini, Tom Dhaene, Luc Knockaert, Albert E. Ruehli

Electrical and Computer Engineering Faculty Research & Creative Works

We present a new model order reduction technique for electrically large systems with delay elements, which can be modeled by means of neutral delayed differential equations. an adaptive multipoint expansion and model order reduction of equivalent first order systems are combined in the new proposed method that preserves the neutral delayed differential formulation. an adaptive algorithm to select the expansion points is presented. the proposed model order reduction technique is validated by pertinent numerical results. a comparison with a previous model order reduction algorithm based on a single point expansion is performed to show the considerably improved modeling capability of …

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Statistical Estimation Of Root Mean Square Crosstalk In Sfp+ Cable Evaluations, Dazhao Liu, Jue Chen, Zhiping Yang, Jun Fan Oct 2011

Statistical Estimation Of Root Mean Square Crosstalk In Sfp+ Cable Evaluations, Dazhao Liu, Jue Chen, Zhiping Yang, Jun Fan

Electrical and Computer Engineering Faculty Research & Creative Works

A rigorous statistical estimation of the root mean square equation is proposed for near-end crosstalk simulation in SFP+ cable evaluations. This method employs the pulse response, the near-end output in the victim pair due to a single-pulse input of one bit long in the aggressor pair. This pulse response can be obtained from vector network analyzer (VNA) measurements. Thus SFP+ cable evaluations can be effectively performed using easier and more accurate frequency-domain measurements, instead of the time-domain ones defined in the specification. © 2011 IEEE.

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Skin-Effect Model For Time And Frequency Domain Peec Solver, Giulio Antonini, Albert E. Ruehli Oct 2011

Skin-Effect Model For Time And Frequency Domain Peec Solver, Giulio Antonini, Albert E. Ruehli

Electrical and Computer Engineering Faculty Research & Creative Works

A challenging issue for the solution of large electromagnetic problems is the efficient modeling of the broadband skin-effect for conducting planes and 3D shapes. the inclusion of such models in an EM solver can be very costly in compute time and memory requirements. Progress has recently been made in the design of skin-effect models. 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 new model which meets some of these challenges and which is suitable for the PEEC solution …

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Characterization And Modeling Of A Grid-Connected Photovoltaic System Using A Recurrent Neural Network, Daniel M. Riley, Ganesh K. Venayagamoorthy Oct 2011

Characterization And Modeling Of A Grid-Connected Photovoltaic System Using A Recurrent Neural Network, Daniel M. Riley, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

Photovoltaic (PV) system modeling is used throughout the photovoltaic industry for the prediction of PV system output under a given set of weather conditions. PV system modeling has a wide range of uses including: prepurchase comparisons of PV system components, system health monitoring, and payback (return on investment) times. in order to adequately model a PV system, the system must be characterized to establish the relationship between given weather inputs (e.g., irradiance, spectrum, temperature) and desired system outputs (e.g., AC power, module temperature). Traditional approaches to system characterization involve characterizing and modeling each component in a PV system and forming …

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High Frequency Permeability Of Fe-Al-Si Granular Composite Materials, Takanori Tsutaoka, Taisuke Ono, Aiko Tsurunaga, Teruhiro Kasagi, Kenichi Hatakeyama, Marina Koledintseva Oct 2011

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 (μr = μr’ – jμr”) and permittivity (εr = εr’ – j εr”) 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 …

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Analysis Of Via Impedance Variations With A Polynomial Chaos Method, Jianxiang Shen, Hanfeng Wang, Ji Chen, Jun Fan Oct 2011

Analysis Of Via Impedance Variations With A Polynomial Chaos Method, Jianxiang Shen, Hanfeng Wang, Ji Chen, Jun Fan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we propose a systematic framework for the optimization and analysis of the equivalent characteristic impedance of practical via structures. the framework consists of (a) optimizing via structures for impedance matching using a Genetic algorithm, and (b) numerically characterize, by Polynomial Chaos (PC) method, the sensitivity of the equivalent characteristic impedance to the manufacturing uncertainties in the various geometrical parameters of a via structure. the PC method can be effectively used to compute important statistical information, such as moments, probabilities and sensitivities with respect to the design variables. the PC method is straightforward to implement and can be …

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