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Electrical and Computer Engineering Faculty Research & Creative Works

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Articles 1201 - 1230 of 3518

Full-Text Articles in Engineering

A Cross Layer Routing Scheme For Passive Rfid Tag-To-Tag Communication, Haifeng Niu, S. Jagannathan Oct 2014

A Cross Layer Routing Scheme For Passive Rfid Tag-To-Tag Communication, Haifeng Niu, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

A routing protocol for Passive RFID tag-to-tag networks is not reported in contrast with routing protocols for battery powered mobile wireless ad hoc and sensor networks. In this paper, we provide a cross-layer approach for passive RFID tag-to-tag communication. In the data link layer, we designed the medium access control (MAC) protocol which is suitable for passive tag-to-tag communication. In the network layer, we developed the optimal link cost multipath routing (OLCMR) protocol by using modulation depth as the link cost. Simulation results verify that proposed routing protocol consumes less energy when it is compared to optimum link state routing …

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Optimal Strategies For Targeted Influence In Signed Networks, Basak Guler, Burak Varan, Kaya Tutuncuoglu, Mohamed Nafea, Ahmed A. Zewail, Aylin Yener, Damien Octeau Oct 2014

Optimal Strategies For Targeted Influence In Signed Networks, Basak Guler, Burak Varan, Kaya Tutuncuoglu, Mohamed Nafea, Ahmed A. Zewail, Aylin Yener, Damien Octeau

Electrical and Computer Engineering Faculty Research & Creative Works

Online social communities often exhibit complex relationship structures, ranging from close friends to political rivals. As a result, persons are influenced by their friends and foes differently. Network applications can benefit from accompanying these structural differences in propagation schemes. In this paper, we study the optimal influence propagation policies for networks with positive and negative relationship types. We tackle the problem of minimizing the end-to-end propagation cost of influencing a target person in favor of an idea by utilizing the relationship types in the underlying social graph. The propagation cost is incurred by social and physical network dynamics such as …

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An Integrated Active Power Filter-Ultracapacitor Design To Provide Intermittency Smoothing And Reactive Power Support To The Distribution Grid, Deepak Somayajula, Mariesa L. Crow Oct 2014

An Integrated Active Power Filter-Ultracapacitor Design To Provide Intermittency Smoothing And Reactive Power Support To The Distribution Grid, Deepak Somayajula, Mariesa L. Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Grid integration of distributed energy resources (DERs) is increasing rapidly. Furthermore, smart grid technologies are making the grid more bi-directional providing opportunities to consumers to supply power back to the grid. Energy storage technologies like battery and ultracapacitor (UCAP) can be integrated through grid-tied inverters to support variable DERs such as solar and wind. In these cases, the energy storage with active power capability can improve grid performance by providing active and reactive power support. In this paper, the concept of providing active/reactive power support and renewable intermittency smoothing to the distribution grid by UCAPs is presented. UCAPs have a …

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An Ultracapacitor Integrated Power Conditioner For Intermittency Smoothing And Improving Power Quality Of Distribution Grid, Deepak Somayajula, Mariesa L. Crow Oct 2014

An Ultracapacitor Integrated Power Conditioner For Intermittency Smoothing And Improving Power Quality Of Distribution Grid, Deepak Somayajula, Mariesa L. Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Penetration of various types of distributed energy resources (DERs) like solar, wind, and plug-in hybrid electric vehicles (PHEVs) onto the distribution grid is on the rise. There is a corresponding increase in power quality problems and intermittencies on the distribution grid. In order to reduce the intermittencies and improve the power quality of the distribution grid, an ultracapacitor (UCAP) integrated power conditioner is proposed in this paper. UCAP integration gives the power conditioner active power capability, which is useful in tackling the grid intermittencies and in improving the voltage sag and swell compensation. UCAPs have low energy density, high-power density, …

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Novel Through-Silicon-Via Inductor-Based On-Chip Dc-Dc Converter Designs In 3d Ics, Umamaheswara Rao Tida, Cheng Zhuo, Yiyu Shi Oct 2014

Novel Through-Silicon-Via Inductor-Based On-Chip Dc-Dc Converter Designs In 3d Ics, Umamaheswara Rao Tida, Cheng Zhuo, Yiyu Shi

Electrical and Computer Engineering Faculty Research & Creative Works

There has been a tremendous research effort in recent years to move DC-DC converters on chip for enhanced performance. However, a major limiting factor to implementing on-chip inductive DC-DC converters is the large area overhead induced by spiral inductors. Thus, we propose using through-silicon-vias (TSVs), a critical enabling technique in three-dimensional (3D) integrated systems, to implement on-chip inductors for DC-DC converters. While existing literature show that TSV inductors are inferior compared with conventional spiral inductors due to substrate loss for RF applications, in this article, we demonstrate that it is not the case for DC-DC converters, which operate at relatively …

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Optimal Pmu Placement For Identification Of Multiple Power Line Outages In Smart Grids, Jie Wu, Jinjun Xiong, Prasenjit Shil, Yiyu Shi Sep 2014

Optimal Pmu Placement For Identification Of Multiple Power Line Outages In Smart Grids, Jie Wu, Jinjun Xiong, Prasenjit Shil, Yiyu Shi

Electrical and Computer Engineering Faculty Research & Creative Works

Placing appropriate numbers of PMUs is critical to collect phase angle data for best identifying multiple line outages in wide-area transmission system, because of high deployment costs. This work focuses on exploring the global optimal strategy of PMU deployment for maximizing the average identification capability of multiple line outages. Inspired by Kullback-Leibler (KL) distance, this paper proposes the closed-form mathematical model to describe the average identification capability of multiple simultaneous line outages. Using IEEE 14-bus system, the optimal trade-off between the average identification capability and the number of PMUs is characterized. The proposed model successfully portrays the statistical identification performance …

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Improved Field Projection In Equivalence Principle Algorithm With Rotated Cwbc Basis, Zu Hui Ma, Sheng Sun, Lijun Jiang, Weng Cho Chew, Mao Kun Li Sep 2014

Improved Field Projection In Equivalence Principle Algorithm With Rotated Cwbc Basis, Zu Hui Ma, Sheng Sun, Lijun Jiang, Weng Cho Chew, Mao Kun Li

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a dual-basis testing method is utilized to enhance the field projection in the equivalence principle algorithm (EPA). Due to the presence of identity operators in the EPA formulation, the near-field calculation is less accurate with field projection errors. This issue can be effectively remedied by using the recently proposed dual-basis function of Rao-Wilton-Glisson basis function, named as rotated Chen-Wilton-Buffa-Christiansen basis function. Numerical result shows the validity of the proposed method.

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A Discontinuous Galerkin Time Domain-Boundary Integral Method For Analyzing Transient Electromagnetic Scattering, Ping Li, Li (Lijun) Jun Jiang, Yifei Shi, Hakan Bagci Sep 2014

A Discontinuous Galerkin Time Domain-Boundary Integral Method For Analyzing Transient Electromagnetic Scattering, Ping Li, Li (Lijun) Jun Jiang, Yifei Shi, Hakan Bagci

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents an algorithm hybridizing discontinuous Galerkin time domain (DGTD) method and time domain boundary integral (BI) algorithm for 3-D open region electromagnetic scattering analysis. The computational domain of DGTD is rigorously truncated by analytically evaluating the incoming numerical flux from the outside of the truncation boundary through BI method based on the Huygens' principle. The advantages of the proposed method are that it allows the truncation boundary to be conformal to arbitrary (convex/ concave) scattering objects, well-separated scatters can be truncated by their local meshes without losing the physics (such as coupling/multiple scattering) of the problem, thus reducing …

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Second-Harmonic Generation In Metal Nanoparticles Modeling By Surface Integral Equation, Xiaoyan Y.Z. Xiong, Li (Lijun) Jun Jiang, Yat Hei Lo, Weng Cho Chew Sep 2014

Second-Harmonic Generation In Metal Nanoparticles Modeling By Surface Integral Equation, Xiaoyan Y.Z. Xiong, Li (Lijun) Jun Jiang, Yat Hei Lo, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

Metals are centrosymmetric materials which only posse local surface second-harmonic (SH) nonlinearities due to the symmetry broken at the surface. In this work the surface integral equation (SIE) is used for evaluating SH radiation generated from metal nanoparticles with arbitrary shapes. The whole SIE system is solved by employing the Galerkin testing procedure and Rao-Wilton-Gillson (RWG) basis functions. The mutual coupling between fundamental and second harmonic field is captured. The method is validated by comparisons with the analytic SH-Mie solution. This method paves the way for accurate and efficient design of general SH nonlinear nanoplasmonic structures.

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Applying Cem Techniques To Solve Nano-Scale Quantum Transport Problems, Jun Z. Huang, Weng Cho Chew, Li (Lijun) Jun Jiang Sep 2014

Applying Cem Techniques To Solve Nano-Scale Quantum Transport Problems, Jun Z. Huang, Weng Cho Chew, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Two widely used algorithms in computational electromagnetics (CEM) society, namely the asymptotic waveform evaluation (AWE) technique and the model order reduction (MOR) mode matching method, are employed to calculate electron wave propagation in novel nanoelectronic devices.

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Linearly Polarized Near Field Focused Slot-Array Waveguide, Meng Lin Chen, Shulabh Gupta, Zi Long Ma, Li (Lijun) Jun Jiang Sep 2014

Linearly Polarized Near Field Focused Slot-Array Waveguide, Meng Lin Chen, Shulabh Gupta, Zi Long Ma, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A 2-D slot array structure to achieve near-field beam focusing, with a linear polarization, is proposed and demonstrated using full-wave simulations. The proposed structure has a negligible cross-polarization and its far-field gain is lower by 10 dB compared to the non-focus case, indicating a good focusing in the near-field of the structure.

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An Ibc Enhanced Dgtd Scheme For Transient Analysis Of Em Interactions With Graphene, Ping Li, Li (Lijun) Jun Jiang, Hakan Baʇci Sep 2014

An Ibc Enhanced Dgtd Scheme For Transient Analysis Of Em Interactions With Graphene, Ping Li, Li (Lijun) Jun Jiang, Hakan Baʇci

Electrical and Computer Engineering Faculty Research & Creative Works

A discontinuous Galerkin time-domain (DGTD) method is proposed for analyzing electromagnetic field interactions on graphene from microwave to terahertz frequencies. An impedance boundary condition (IBC) is utilized to model the graphene within the DGTD framework. The numerical flux is reformulated to take into account the IBC. Highly dispersive surface conductivity of graphene present in the resulting flux expression is approximated in terms of rational functions using the fast-relaxation vector-fitting technique. Via inverse Laplace transform, this facilitates the time domain matrix equations into an integral form for time variable t, finite integral technique (FIT) with recursive convolution method is employed to …

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Reduced-Permittivity Meandered Single-Beam Full-Space Scanning Phase-Reversal Leaky-Wave Antenna, Shulabh Gupta, Li (Lijun) Jun Jiang, Christophe Caloz Sep 2014

Reduced-Permittivity Meandered Single-Beam Full-Space Scanning Phase-Reversal Leaky-Wave Antenna, Shulabh Gupta, Li (Lijun) Jun Jiang, Christophe Caloz

Electrical and Computer Engineering Faculty Research & Creative Works

A meandered version of the phase-reversal leaky-wave antenna is introduced to reduce the permittivity requirement εeff > 4 for single-beam full-space scanning.

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"Green" On-Chip Inductors In Three-Dimensional Integrated Circuits, Umamaheswara Rao Tida, Varun Mittapalli, Cheng Zhuo, Yiyu Shi Sep 2014

"Green" On-Chip Inductors In Three-Dimensional Integrated Circuits, Umamaheswara Rao Tida, Varun Mittapalli, Cheng Zhuo, Yiyu Shi

Electrical and Computer Engineering Faculty Research & Creative Works

Through-silicon-vias (TSVs) are the enabling technique for three-dimensional integrated circuits (3D ICs). However, their large area significantly reduces the benefits that can be obtained by 3D ICs. On the other hand, a major limiting factor for the implementation of many on-chip circuits such as DC-DC converters and resonant clocking is the large area overhead induced by spiral inductors. Several works have been proposed in the literature to make inductors out of idle TSVs. In this paper, we will demonstrate the effectiveness of such TSV inductors in addressing both challenges. Experimental results show that by replacing conventional spiral inductors with TSV …

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Calderón Preconditioned Pmchwt Equation For Layered Medium Problems, Yongpin P. Chen, Lijun Jiang, Sheng Sun, Weng Cho Chew Sep 2014

Calderón Preconditioned Pmchwt Equation For Layered Medium Problems, Yongpin P. Chen, Lijun Jiang, Sheng Sun, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic scattering by dielectric objects in the presence of a layered medium is investigated by applying the Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) equation combined with the layered medium Green's function. Due to the electric field integral equation (EFIE) operator involved, the spectrum of the PMCHWT equation is also undesired. When the surface is densely discretized, the condition of the resulting matrix is extremely bad. An effective Calderón preconditioner is developed in this paper to improve the convergence. Different from its free space counterpart, the Calderón identities for inhomogeneous medium need to be re-derived. It is shown from numerical examples that the convergence of …

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Augmented Equivalence Principle Algorithm For Domain Decomposition Method For Low Frequency Scattering, Circuits, And Casimir Force Calculations, P. R. Atkins, Z. H. Ma, L. E. Sun, M. K. Li, L. (Lijun) J. Jiang, M. S. Tong, W. C. Chew Sep 2014

Augmented Equivalence Principle Algorithm For Domain Decomposition Method For Low Frequency Scattering, Circuits, And Casimir Force Calculations, P. R. Atkins, Z. H. Ma, L. E. Sun, M. K. Li, L. (Lijun) J. Jiang, M. S. Tong, W. C. Chew

Electrical and Computer Engineering Faculty Research & Creative Works

A broadband integral-equation-based domain decomposition method (DDM) using augmented equivalence principle algorithm (A-EPA) is introduced for solving large scale electromagnetic scattering, circuits, and Casimir force problems. The root cause of the low frequency breakdown problem of EPA algorithm without augmentation technique is analyzed. Numerical examples validate the method for various applications in scattering, circuits, and Casimir force calculations.

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The Contour Deformation Method For Calculating The High Frequency Scattered Fields By The Fock Current On The Surface Of The 3-D Convex Cylinder, Yu Mao Wu, Li (Lijun) Jun Jiang, Weng Cho Chew Sep 2014

The Contour Deformation Method For Calculating The High Frequency Scattered Fields By The Fock Current On The Surface Of The 3-D Convex Cylinder, Yu Mao Wu, Li (Lijun) Jun Jiang, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

In this work, the Fock currents on the convex cylinders are comprehensively studied. The contour deformation method is invoked to calculate the highly oscillatory Fock currents. The computational process is frequency independent in workload. Then, quadratic phase approximation is proposed to efficiently solve the highly oscillatory scattered field. Numerical results for the high frequency scattered far fields on the convex cylinders are given to validate the efficiency of the proposed method. Furthermore, the contour deformation method for computing the Fock currents offers a clear high frequency wave physical picture.

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Analysis Of Scattering By Pec Objects In Layered Medium With Calderón Preconditioner, Yongpin P. Chen, Min Meng, Sheng Sun, Lijun Jiang, Weng Cho Chew Sep 2014

Analysis Of Scattering By Pec Objects In Layered Medium With Calderón Preconditioner, Yongpin P. Chen, Min Meng, Sheng Sun, Lijun Jiang, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic scattering by perfect electrically conducting (PEC) objects in a layered medium is studied in this paper. The layered medium Green's function is adopted as the kernel of the electric field integral equation (EFIE) so that the effects from the multilayered background can be accounted for automatically. However, the spectrum of the EFIE with this kernel, is unfortunately undesirable. This leads to slow convergence of the iterative solution. To improve the convergence, the Calderón identities are derived and leveraged to precondition the EFIE. By utilizing Buffa-Christiansen (BC) basis function in discretizing the preconditioning operator, the preconditioner can be made completely …

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Differential Forms Inspired Finite Element Discretization For Waveguide Eigenvalue Problems, Qi I. Dai, Weng Cho Chew, Lijun Jiang Sep 2014

Differential Forms Inspired Finite Element Discretization For Waveguide Eigenvalue Problems, Qi I. Dai, Weng Cho Chew, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A differential forms inspired finite element based discretization scheme for waveguide eigenvalue problems is presented. Naïve discretization of the governing variational expression involving only transverse fields with edge elements renders the discretized eigen-equation unsolvable. Motivated by differential forms, in the proposed scheme, electric and magnetic fields are discretized with curl-conforming basis functions on the primal and dual grids, respectively. Meanwhile, magnetic flux density and electric displacement fields are discretized with divergence-conforming basis functions on the primal and dual grids, respectively. Matrices in the resultant eigen-equation is well-conditioned and easy to solve, which is validated by several numerical examples.

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Uncertainty Quantification Of Em-Circuit Systems Using Stochastic Polynomial Chaos Method, Ping Li, Li (Lijun) Jun Jiang Sep 2014

Uncertainty Quantification Of Em-Circuit Systems Using Stochastic Polynomial Chaos Method, Ping Li, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Uncertainties in realistic lumped and distributive circuit systems are of great importance to today's high yield manufacture demand. However, evaluating the stochastic effect in the time domain for the hybrid electromagnetics (EM)-circuit system was seldom done, especially when Monte Carlo is too expensive to be feasible. In this work, an adaptive hierarchical sparse grid collocation (ASGC) method is presented to quantify the impacts of stochastic inputs on hybrid electromagnetics (EM)-circuit or EM scattering systems. The ASGC method approximates the stochastic observables of interest using interpolation functions over series collocation points. Instead of employing a full-tensor product sense, the collocation points …

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Effective Roughness Dielectric In A Pcb: Measurement And Full-Wave Simulation Verification, Tracey Vincent, Marina Koledintseva, Antonio Ciccomancini, Scott Hinaga Sep 2014

Effective Roughness Dielectric In A Pcb: Measurement And Full-Wave Simulation Verification, Tracey Vincent, Marina Koledintseva, Antonio Ciccomancini, Scott Hinaga

Electrical and Computer Engineering Faculty Research & Creative Works

Surface roughness topography of printed circuit boards (PCBs) needs to be included in SI simulations in order to accurately predict the insertion loss of the structure. An effective roughness dielectric (ERD) model can be used to substitute an inhomogeneous interface between copper foil and laminate dielectric in a PCB. Herein, this approach is tested for verification using 3D full-wave numerical simulations. These effective roughness dielectric layers with the appropriate complex permittivity are included in the modeling of strip line examples. The parameters of an ambient laminate dielectric free of conductor roughness effects in the strip line are determined using differential …

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A Generalized Proportionate Adaptive Algorithm Based On Convex Optimization, Jianming Liu, Steven L. Grant Sep 2014

A Generalized Proportionate Adaptive Algorithm Based On Convex Optimization, Jianming Liu, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

A general framework is proposed to derive proportionate adaptive algorithms for sparse system identification. The proposed algorithmic framework employs the convex optimization and covers many traditional proportionate algorithms. Meanwhile, based on this framework, some novel proportionate algorithms could be derived too. In the simulations, we compare the new derived proportionate algorithm with the traditional ones and demonstrate that it could provide faster convergence rate and tracking performance for both white and colored input in sparse system identification.

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Near Optimal Event-Based Control Of Nonlinear Discrete Time Systems In Affine Form With Measured Input And Output Data, Avimanyu Sahoo, Hao Xu, S. Jagannathan Sep 2014

Near Optimal Event-Based Control Of Nonlinear Discrete Time Systems In Affine Form With Measured Input And Output Data, Avimanyu Sahoo, Hao Xu, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, an event-based near optimal control of uncertain nonlinear discrete time systems is presented by using input-output data and approximate dynamic programming (ADP). The nonlinear system dynamics in affine form are transformed into an input-output form. Then, three neural networks (NN) with event sampled input-output vector are used, namely, the identifier NN to relax the knowledge of the system dynamics, a critic NN to approximate the value function which is the solution to the Hamilton-Jacobi Bellman (HJB) equation, and an actor NN to approximate the optimal control policy, in an online manner without utilizing value or policy iterations. …

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Finite Horizon Stochastic Optimal Control Of Nonlinear Two-Player Zero-Sum Games Under Communication Constraint, Hao Xu, S. Jagannathan Sep 2014

Finite Horizon Stochastic Optimal Control Of Nonlinear Two-Player Zero-Sum Games Under Communication Constraint, Hao Xu, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the finite horizon stochastic optimal control of nonlinear two-player zero-sum games, referred to as Nonlinear Networked Control Systems (NNCS) two-player zero-sum game, between control and disturbance input players in the presence of unknown system dynamics and a communication network with delays and packet losses is addressed by using neuro dynamic programming (NDP). The overall objective being to find the optimal control input while maximizing the disturbance attenuation. First, a novel online neural network (NN) identifier is introduced to estimate the unknown control and disturbance coefficient matrices which are needed in the generation of optimal control input. Then, …

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Transmit Designs For The Mimo Broadcast Channel With Statistical Csi, Yongpeng Wu, Shi Jin, Xiqi Gao, Matthew R. Mckay, Chengshan Xiao Sep 2014

Transmit Designs For The Mimo Broadcast Channel With Statistical Csi, Yongpeng Wu, Shi Jin, Xiqi Gao, Matthew R. Mckay, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

We investigate the multiple-input multiple-output broadcast channel with statistical channel state information available at the transmitter. The so-called linear assignment operation is employed, and necessary conditions are derived for the optimal transmit design under general fading conditions. Based on this, we introduce an iterative algorithm to maximize the linear assignment weighted sum-rate by applying a gradient descent method. To reduce complexity, we derive an upper bound of the linear assignment achievable rate of each receiver, from which a simplified closed-form expression for a near-optimal linear assignment matrix is derived. This reveals an interesting construction analogous to that of dirty-paper coding. …

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Stochastic Optimal Design For Unknown Linear Discrete-Time System Zero-Sum Games In Input-Output Form Under Communication Constraints, Hao Xu, S. Jagannathan, F. L. Lewis Sep 2014

Stochastic Optimal Design For Unknown Linear Discrete-Time System Zero-Sum Games In Input-Output Form Under Communication Constraints, Hao Xu, S. Jagannathan, F. L. Lewis

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, stochastic optimal strategy for unknown linear discrete-time system quadratic zero-sum games in input-output form with communication imperfections such as network-induced delays and packet losses, otherwise referred to as networked control system (NCS) zero-sum games, relating to the H∞ optimal control problem is solved in a forward-in-time manner. First, the linear discrete-time zero sum state space representation is transformed into a linear NCS in the state space form after incorporating random delays and packet losses and then into the input-output form. Subsequently, the stochastic optimal approach, referred to as adaptive dynamic programming (ADP), is introduced which estimates the …

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First Demonstration Of Ultra-Thin Sige-Channel Junctionless Accumulation-Mode (Jam) Bulk Finfets On Si Substrate With Pn Junction-Isolation Scheme, Donghyun Kim, Tae Kyun Kim, Young Gwang Yoon, Byeong Woon Hwang, Yang-Kyu Choi, Byung Jin Cho, Seok-Hee Lee Sep 2014

First Demonstration Of Ultra-Thin Sige-Channel Junctionless Accumulation-Mode (Jam) Bulk Finfets On Si Substrate With Pn Junction-Isolation Scheme, Donghyun Kim, Tae Kyun Kim, Young Gwang Yoon, Byeong Woon Hwang, Yang-Kyu Choi, Byung Jin Cho, Seok-Hee Lee

Electrical and Computer Engineering Faculty Research & Creative Works

A SiGe-channel junctionless-accumulation-mode (JAM) PMOS bulk FinFETs were successfully demonstrated on Si substrate with PN junction-isolation scheme for the first time. The JAM bulk FinFETs with fin width of 18 nm exhibits excellent subthreshold characteristics such as subthreshold swing of 64 mV/decade, drain-induced barrier lowering (DIBL) of 40 mV/V and high Ion/Ioff current ratio ( > 1 x 105). The change of substrate bias from 0 to 5 V leads to the threshold voltage shift of 53 mV by modulating the effective channel thickness. When compared to the Si-channel bulk FinFETs with fin width of 18 …

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Simplified Parallel Interference Cancelation For Underdetermined Mimo Systems, Chen Qian, Jingxian Wu, Yahong Rosa Zheng, Zhaocheng Wang Sep 2014

Simplified Parallel Interference Cancelation For Underdetermined Mimo Systems, Chen Qian, Jingxian Wu, Yahong Rosa Zheng, Zhaocheng Wang

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a low-complexity detection scheme is proposed for an underdetermined multiple-input-multiple-output (UD-MIMO) wireless communication system that employs N transmit antennas and M < N receive antennas. The proposed scheme combines a simplified parallel interference cancelation (S-PIC) with the block decision feedback equalization (BDFE) algorithm. To account for the extra (N - M)-dimension in the transmitted signal, the UD-MIMO system is partitioned into two subsystems: one with (N - M) transmit antennas and the other one with M transmit antennas. The interference from the first subsystem to the second one is canceled in parallel, and BDFE is performed over the second subsystem. Unlike conventional PIC methods that exhaustively search all the Q (N - M) sequences in the first subsystem, with Q being the constellation size, the proposed scheme explores only a small number of candidate sequences in the first subsystem; thus, it achieves significant complexity reduction. Two new candidate sequence selection methods are proposed. In the first iteration, the candidate sequences used for PIC are selected by exploring the statistical properties of the received signals. In the second iteration and beyond, the set containing the candidate sequences is constructed by utilizing the soft information generated from the previous iteration. The proposed scheme provides a balanced tradeoff between computational complexity and bit error rate (BER) performance.

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Comparison Of Synthetic Aperture Radar And Impact-Echo Imaging For Detecting Delamination In Concrete, John S. Popovics, Suyun Ham, Mohammad Tayeb Ahmad Ghasr, R. Zoughi Jul 2014

Comparison Of Synthetic Aperture Radar And Impact-Echo Imaging For Detecting Delamination In Concrete, John S. Popovics, Suyun Ham, Mohammad Tayeb Ahmad Ghasr, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper we evaluate the utility of microwave and mechanical wave nondestructive testing techniques to detect delamination in reinforced concrete bridge deck mock-up samples. The mechanical wave tests comprise air-coupled impact-echo measurements, while the microwave measurements comprise three-dimensional synthetic aperture radar imaging using wideband reflectometery in the frequency range of 1-4 GHz. The results of these investigations are presented in terms of images that are generated from these data. Based on a comparison of the results, we show that the two methods are complementary, in that provide distinct capabilities for defect detection. More specifically, the former approach is unable …

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Spatially Continuous Distributed Fiber Optic Sensing Using Optical Carrier Based Microwave Interferometry, Jie Huang, Xinwei Lan, Ming Luo, Hai Xiao Jul 2014

Spatially Continuous Distributed Fiber Optic Sensing Using Optical Carrier Based Microwave Interferometry, Jie Huang, Xinwei Lan, Ming Luo, Hai Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

This paper reports a spatially continuous distributed fiber optic sensing technique using optical carrier based microwave interferometry (OCMI), in which many optical interferometers with the same or different optical path differences are interrogated in the microwave domain and their locations can be unambiguously determined. The concept is demonstrated using cascaded weak optical reflectors along a single optical fiber, where any two arbitrary reflectors are paired to define a low-finesse Fabry-Perot interferometer. While spatially continuous (i.e., no dark zone), fully distributed strain measurement was used as an example to demonstrate the capability, the proposed concept may also be implemented on other …

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