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Electrical and Computer Engineering Faculty Research & Creative Works

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Articles 1021 - 1050 of 3518

Full-Text Articles in Engineering

Strongly Enhanced And Directionally Tunable Second-Harmonic Radiation From A Plasmonic Particle-In-Cavity Nanoantenna, Xiaoyan Y.Z. Xiong, Li (Lijun) Jun Jiang, Wei E.I. Sha, Yat Hei Lo, Ming Fang, Weng Cho Chew, Wallace C.H. Choy Nov 2016

Strongly Enhanced And Directionally Tunable Second-Harmonic Radiation From A Plasmonic Particle-In-Cavity Nanoantenna, Xiaoyan Y.Z. Xiong, Li (Lijun) Jun Jiang, Wei E.I. Sha, Yat Hei Lo, Ming Fang, Weng Cho Chew, Wallace C.H. Choy

Electrical and Computer Engineering Faculty Research & Creative Works

Second-harmonic (SH) generation is tremendously important for nonlinear sensing, microscopy, and communication systems. One of the great challenges of current designs is to enhance the SH signal and simultaneously tune its radiation direction with a high directivity. In contrast to the linear plasmonic scattering dominated by a bulk dipolar mode, a complex surface-induced multipolar source at the doubled frequency sets a fundamental limit to control the SH radiation from metallic nanostructures. In this work, we harness a plasmonic hybridization mechanism together with a special selection rule governing the SH radiation to achieve the high-intensity and tunable-direction emission by a metallic …

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A Study Of Scattering From A Layer Of Random Discrete Medium With Hierarchical Equivalent Source Algorithm (Hesa), Chan Fai Lum, Fu Xin, Hong Tat Ewe, Li (Lijun) Jun Jiang Nov 2016

A Study Of Scattering From A Layer Of Random Discrete Medium With Hierarchical Equivalent Source Algorithm (Hesa), Chan Fai Lum, Fu Xin, Hong Tat Ewe, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

This paper is to present a new numerical method which can be used in computational electromagnetics in microwave remote sensing of random discrete medium embedded with irregular shape of scatterers. Current Radiative Transfer (RT) theoretical modeling is normally used to simulate wave propagation in the medium and wave scattering by basic shapes of scatterers, e.g., cylinder, disk, needle or sphere where the scattering of those scatterers was normally derived analytically with some assumption and approximation. To simulate the total backscattering coefficient from a layer of random medium, traditionally it was quite common that Mie phase matrix was used to compute …

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Right-Hand Side Effect On The Convergence Of Integral Equation Based Systems, Qin S. Liu, Sheng Sun, Weng Cho Chew, Qi I. Dai, Li (Lijun) Jun Jiang Nov 2016

Right-Hand Side Effect On The Convergence Of Integral Equation Based Systems, Qin S. Liu, Sheng Sun, Weng Cho Chew, Qi I. Dai, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A study of the right-hand side effect for an iterative solver is presented. The right-hand side determines whether a mode can be excited under certain excitation. Based on the matrix equation system Ā · x = b, different formulations are discussed including the electric field integral equation (EFIE), Calderón preconditioned EFIE with electro-quasi-static problems, and the magnetic integral equation (MFIE) with magneto-quasi-static problems. Detailed spectral analysis shows the importance of the weighted right-hand side effect in both the convergence and accuracy of iterative system.

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Operator Splitting For Quasi-Linear Abstract Hyperbolic Equation, N. Dikhaminjia, J. Rogava, Mikheil Tsiklauri Nov 2016

Operator Splitting For Quasi-Linear Abstract Hyperbolic Equation, N. Dikhaminjia, J. Rogava, Mikheil Tsiklauri

Electrical and Computer Engineering Faculty Research & Creative Works

We consider an abstract hyperbolic equation with a Lipschitz continuous operator, where the main operator is self-adjoint and positive definite and represents a sum of two similar operators. For this equation, we construct a decomposition scheme of high order of accuracy. This scheme is based on rational splitting of cosine-operator function.

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Polarization Control By Using Anisotropic 3-D Chiral Structures, Menglin L.N. Chen, Li (Lijun) Jun Jiang, Wei E.I. Sha, Wallace C.H. Choy, Tatsuo Itoh Nov 2016

Polarization Control By Using Anisotropic 3-D Chiral Structures, Menglin L.N. Chen, Li (Lijun) Jun Jiang, Wei E.I. Sha, Wallace C.H. Choy, Tatsuo Itoh

Electrical and Computer Engineering Faculty Research & Creative Works

Due to the mirror symmetry breaking, chiral structures show fantastic electromagnetic (EM) properties involving negative refraction, giant optical activity, circular dichroism and asymmetric transmission. Aligned electric and magnetic dipoles excited in chiral structures contribute to the extraordinary properties. However, the chiral structures that exhibit n -fold rotational symmetry show a limited tunability of the chirality. In this paper, we propose a compact, light, and highly tunable anisotropic chiral structure to overcome this limitation and realize a linear-to-circular polarization conversion. The anisotropy is due to simultaneous excitations of two different pairs of aligned electric and magnetic dipoles. The 3-D omega-shaped structure, …

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Stochastic Galerkin Methods For Transient Maxwell's Equations With Random Geometries, Yongtao Cheng, Li (Lijun) Jun Jiang Oct 2016

Stochastic Galerkin Methods For Transient Maxwell's Equations With Random Geometries, Yongtao Cheng, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

The generalized polynomial chaos expansion was broadly introduced to model systems with uncertain inputs, including random material properties and random computational geometries. This paper focuses solving electromagnetic field when the geometry contains multi-randomness. A linear transformation always maps spatial random variables into grids with fixed length. Hence a great advantage of the method is that the numerical mesh is not changed despite geometrical variations. We applied efficient stochastic Galerkin methods to time-domain Maxwell's equations when thicknesses of two-layer media are uncertain. High-order Runge-Kutta discontinuous Galerkin methods were performed on the resulting system of the expansion coefficients.

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Enhanced Second Harmonic Generation In A Plasmonic Particle-In-Cavity Nanoantenna, Xiaoyan Y.Z. Xiong, Li (Lijun) Jun Jiang, Wei E.I. Sha, Yat Hei Lo Oct 2016

Enhanced Second Harmonic Generation In A Plasmonic Particle-In-Cavity Nanoantenna, Xiaoyan Y.Z. Xiong, Li (Lijun) Jun Jiang, Wei E.I. Sha, Yat Hei Lo

Electrical and Computer Engineering Faculty Research & Creative Works

Plasmonic nanostructures that support surface plasmon resonances potentially provide a route for the development of nanoengineered nonlinear optical media. A strong enhancement of second harmonic generation (SHG) in a particle-in-cavity nanoantenna (PIC-NA) is proposed and theoretically demonstrated in this work. The fundamental and second harmonic responses of the PIC-NA are calculated using a self-consistent boundary element method. Through a comparison with the linear field enhancement spectra, the SHG from PIC-NA is boosted by the strongly enhanced fundamental and SH fields arising from the cascaded focusing of large optical energy into the small gap. The proposed 3D plasmonic PIC-NA functions as …

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Characteristic Analysis For Optical Antennas: A Generalized Equivalent Circuit Model For Nanoparticles, Ying S. Cao, Li (Lijun) Jun Jiang Oct 2016

Characteristic Analysis For Optical Antennas: A Generalized Equivalent Circuit Model For Nanoparticles, Ying S. Cao, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Optical antennas, which are considered for many potential applications, are antennas which work at optical frequencies. At this frequency range, the materials, such as Al, Ag, Au and so on, formerly treated as perfect electric conductor (PEC), now have dispersive and complex permittivity, which complicates most of the methodologies. In this paper, a generalized equivalent circuit model is developed for nanoantennas not only to deal with the dispersivity of permittivity, but also to provide more physical insight. Several examples are used to benchmark the method.

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Orbital Angular Momentum (Oam) Generation By Composite Pec-Pmc Metasurfaces In Microwave Regime, Menglin L.N. Chen, Li (Lijun) Jun Jiang, Wei E.I. Sha Oct 2016

Orbital Angular Momentum (Oam) Generation By Composite Pec-Pmc Metasurfaces In Microwave Regime, Menglin L.N. Chen, Li (Lijun) Jun Jiang, Wei E.I. Sha

Electrical and Computer Engineering Faculty Research & Creative Works

Besides amplitude, phase and polarization, wave-front is also an important property of electromagnetic waves. EM waves with helical wavefront carrying orbital angular momentum (OAM) attract more attentions recently for its promising applications in communications. The OAM generation for microwaves was rarely reported. And existing designs are usually very complicated and suffer low efficiency problems. We propose composite PEC (perfect electric conductor)-PMC (perfect magnetic conductor) metasurfaces to convert the LCP (RCP) plane wave with zero OAM to the RCP (LCP) helical EM wave with desired OAM at microwave regime. The conversion efficiency can nearly reach 100%.

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A Novel Coordinate Transformation Based Self-Coupling Computation Approach For The Method Of Moments, Li Li, Lijun Jiang, Sheng Sun, Thomas F. Eibert, Weng Cho Chew Oct 2016

A Novel Coordinate Transformation Based Self-Coupling Computation Approach For The Method Of Moments, Li Li, Lijun Jiang, Sheng Sun, Thomas F. Eibert, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

A new highly accurate and efficient coordinate transformation algorithm is proposed for the evaluation of the self-coupling in the Method of Moments (MoM), which produces usually the strongest contributions to the MoM system matrices. The new algorithm provides an effective solution to remove the singularity due to the Green's function inside the self-couplings. Moreover, the new solution reduces the integral dimension from 4-D to 1-D. Thus, better accuracy and efficiency are obtained for the self-coupling integrals.

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A Patch-Resonator-Based Butler Matrix With New Triangular Phase Shifters, Xianshi Jing, Li (Lijun) Jun Jiang, Sheng Sun, Lei Zhu Oct 2016

A Patch-Resonator-Based Butler Matrix With New Triangular Phase Shifters, Xianshi Jing, Li (Lijun) Jun Jiang, Sheng Sun, Lei Zhu

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a new novel patch based Butler Matrix using 3-dB square-patch coupler and triangular-patch wideband phase shifter is presented. By inserting a via hole along the symmetrical plane of the triangular patch, the bandwidth of the transmitting response is significantly increased. In order to obtain a 45° phase difference and a wideband phase response, a reference line with high characteristic impedance is applied and the length of the feeding line for the triangular-patch structure is adjusted correspondingly. As an application, a patch-based Butler Matrix is designed and fabricated around 4 GHz. The measured patch-based Butler Matrix shows a …

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A Highly Tunable Sub-Wavelength Chiral Structure For Circular Polarizer, Menglin L.N. Chen, Li (Lijun) Jun Jiang, Wei E.I. Sha, Tatsuo Itoh Oct 2016

A Highly Tunable Sub-Wavelength Chiral Structure For Circular Polarizer, Menglin L.N. Chen, Li (Lijun) Jun Jiang, Wei E.I. Sha, Tatsuo Itoh

Electrical and Computer Engineering Faculty Research & Creative Works

Chiral structures are composed of periodically arranged asymmetric particles. The asymmetry of chiral particles results in extraordinary properties like negative refraction index, giant optical activity and circular dichroism. Consequently, they have applications in super lens and various polarization controllers. There are two types of chiral structures, namely planar and 3D structures. The planar ones usually have three- or fourfold rotational symmetry, which limits the polarization tuning capability. On the other hand, the 3D prototypes are difficult to fabricate and measure. Here, we propose a highly tunable sub-wavelength 3D chiral structure. It can be conveniently manufactured on the single-layer double-side printed …

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Finite-Difference Time-Domain Simulation Of The Maxwell-Schrödinger System, Christopher Ryu, Aiyin Liu, Weng C. Chew, Wei Sha, Lijun Jiang Oct 2016

Finite-Difference Time-Domain Simulation Of The Maxwell-Schrödinger System, Christopher Ryu, Aiyin Liu, Weng C. Chew, Wei Sha, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A thorough study on the finite-difference time-domain (FDTD) simulation of the Maxwell-Schrödinger system in the semi-classical regime is given. For the Maxwell part which is treated classically, an alternative approach directly using the vector and scalar potentials (A and Φ) is taken. This approach is stable in the long wavelength regime and removes the need to extract the potentials at every time step. Perfectly matched layer (PML) is developed for this system. For the Schrödinger and quantum mechanical part, minimal coupling is applied to couple the charges to the electromagnetic potentials. Simulation results agree with the theory of quantum coherent …

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A New Multiple Access Wiretap Channel Model, Mohamed Nafea, Aylin Yener Oct 2016

A New Multiple Access Wiretap Channel Model, Mohamed Nafea, Aylin Yener

Electrical and Computer Engineering Faculty Research & Creative Works

A new model for the two-user multiple-access wiretap channel is considered. In this model, the legitimate (main) channel is a discrete memoryless channel (DMC), and the wiretapper chooses a fixed-length subset of the channel uses where she has perfect access to the transmitted symbols of both users, while observing the remainder of the transmitted codewords through a second DMC. As such, it generalizes the existing multiple-access wiretap channel models and extends the recently proposed new wiretap channel model to a multiple access setting. An achievable strong secrecy rate region for the model is derived. The achievability is established by solving …

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The Numerical Contour Deformation Method For Calculating High Frequency Scattered Fields From The 3-D Convex Scatters, Yu Mao Wu, Weng Cho Chew, Ya Qiu Jin, Tie Jun Cui, Li (Lijun) Jun Jiang Oct 2016

The Numerical Contour Deformation Method For Calculating High Frequency Scattered Fields From The 3-D Convex Scatters, Yu Mao Wu, Weng Cho Chew, Ya Qiu Jin, Tie Jun Cui, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

We consider the accuracy improvement of the high frequency scattered fields from the 3-D convex scatter by the Fock current and the incremental length diffraction coefficient (ILDC) technique. We propose the numerical contour deformation method to calculate the Fock currents, and treat them in the scatterer's lit and shadow regions, separately. Then, by adopting the ILDC technique, high frequency scattered fields are clearly formulated in the lit, shadow and transition regions of the 3-D convex scatter, respectively. Compared to the PO scattered field from the 3-D convex sphere, numerical results demonstrate the significant accuracy enhancement of the scattered field via …

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Investigation Of 12 Μm 4h-Sic Epilayers For Radiation Detection And Noise Analysis Of Front-End Readout Electronics, Khai V. Nguyen, Rahmi O. Pak, Cihan Oner, Feng Zhao, Krishna C. Mandal Oct 2016

Investigation Of 12 Μm 4h-Sic Epilayers For Radiation Detection And Noise Analysis Of Front-End Readout Electronics, Khai V. Nguyen, Rahmi O. Pak, Cihan Oner, Feng Zhao, Krishna C. Mandal

Electrical and Computer Engineering Faculty Research & Creative Works

Schottky barrier radiation detectors were fabricated on 12 μm n-type 4H-SiC epitaxial layers grown on a 4° off-axis highly doped 4H-SiC substrate (0001). Schottky barrier junction properties were characterized through current-voltage (I-V) and capacitance-voltage (C-V) measurements. A diode ideality factor of 1.29 and Schottky barrier height of 1.10 eV were determined from the forward I-V characteristics using a thermionic emission model. A built-in potential of 1.91 V and effective carrier concentration of 1.03 x 1015 cm-3 was calculated from a Mott-Schottky plot of the C-V measurements. Radiation detector performance was evaluated by alpha pulse height spectroscopy (PHS) in …

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On The Optimal Threshold Voltage Computation Of On-Chip Noise Sensors, Tao Wang, Chun Zhang, Jinjun Xiong, Pei Wen Luo, Liang Chia Cheng, Yiyu Shi Oct 2016

On The Optimal Threshold Voltage Computation Of On-Chip Noise Sensors, Tao Wang, Chun Zhang, Jinjun Xiong, Pei Wen Luo, Liang Chia Cheng, Yiyu Shi

Electrical and Computer Engineering Faculty Research & Creative Works

Runtime noise management systems typically rely on on-chip noise sensors to accurately capture voltage emergencies. As such, the threshold voltage for noise sensors to report emergencies serves as a critical tuning knob between the system failure rate and false alarms. Unfortunately, the problem of optimal threshold voltage computation remains open in literature despite its importance. The problem is further complicated by process variations, which introduce significant variations in load currents and thus in noise across different chips. A uniform noise margin may not work optimally for all the chips. In this paper, we first formulate the problem of minimizing the …

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Comparison Of Mixed-Mode S-Parameters In Weak And Strong Coupled Differential Pairs, Marina Koledintseva, Tracey Vincent Sep 2016

Comparison Of Mixed-Mode S-Parameters In Weak And Strong Coupled Differential Pairs, Marina Koledintseva, Tracey Vincent

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, it is studied how the rate of coupling (weak vs. strong) in edge-coupled differential transmission lines on a printed circuit board (PCB) affects frequency behavior of mixed-mode S-parameters. This is important for signal integrity (SI), and also may be useful from electromagnetic compatibility (EMC) point of view, since the enhancement of mode conversion (from common-mode to differential mode, and vice versa) may result in common-mode noise in high-speed digital electronics. Slightly imbalanced in length microstrip and strip line differential pairs are considered. The study is done using full-wave numerical electromagnetic simulations. Various technological features are modeled in …

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A Novel Beam-Steering Nonlinear Nanoantenna With Surface Plasmon Resonance, Xiaoyan Y.Z. Xiong, Li (Lijun) Jun Jiang, Wei E.I. Sha, Yat Hei Lo, Weng Cho Chew Sep 2016

A Novel Beam-Steering Nonlinear Nanoantenna With Surface Plasmon Resonance, Xiaoyan Y.Z. Xiong, Li (Lijun) Jun Jiang, Wei E.I. Sha, Yat Hei Lo, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

Plasmonic nanostructures that support surface plasmon (SP) resonance potentially provide a route for the development of nanoengineered nonlinear optical media. In this work, a novel plasmonic particle-in-cavity nanoantenna (PIC-NA) is proposed. The second harmonic generation (SHG) of the PIC-NA under strong localized SP resonance is systematically analyzed by a self-consistent numerical solution based on boundary element method (BEM). The developed method solves the fundamental field and second harmonic (SH) field together iteratively to capture their mutual coupling. Strong enhancement of SHG from PIC-NA is achieved. The SHG enhancement factor is around four orders of magnitude, which is much higher than …

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A Full Wave Conductor Modeling Using Augmented Electric Field Integral Equation, Tian Xia, Hui Gan, Michael Wei, Qin Liu, Lijun Jiang, Weng Cho Chew, Henning Braunisch, Kemal Aygun, Zhiguo Qian, Alaeddin Aydiner Sep 2016

A Full Wave Conductor Modeling Using Augmented Electric Field Integral Equation, Tian Xia, Hui Gan, Michael Wei, Qin Liu, Lijun Jiang, Weng Cho Chew, Henning Braunisch, Kemal Aygun, Zhiguo Qian, Alaeddin Aydiner

Electrical and Computer Engineering Faculty Research & Creative Works

A numerical full wave solver is proposed to solve conductor problems in electromagnetics. This method is an extension of the dielectric augmented electric field integral equation (D-AEFIE). Using this method, conductors, from lowly lossy to highly lossy, can be rigorously modeled to capture the conductive losses. Broadband stability can be achieved, thanks to the introduction of the augmentation technique. This paper demonstrates the formulation of this method. A simple and effective preconditioner is introduced to accelerate the convergence. A novel integration scheme is adopted to accurately capture the losses inside the conductor. Finally some numerical examples are shown to support …

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Coupling Dgtd And Behavioral Macromodel For Transient Heterogeneous Electromagnetic Simulations, Huan Huan Zhang, Li (Lijun) Jun Jiang, He Ming Yao, Yu Zhang Sep 2016

Coupling Dgtd And Behavioral Macromodel For Transient Heterogeneous Electromagnetic Simulations, Huan Huan Zhang, Li (Lijun) Jun Jiang, He Ming Yao, Yu Zhang

Electrical and Computer Engineering Faculty Research & Creative Works

A novel transient field-circuit cosimulation method based on the discontinuous Galerkin time domain (DGTD) method and circuit behaviour macromodels for heterogeneous electromagnetics such as EMC problems is proposed. The traditional field-circuit simulation method needs to know the detail of the circuits, which cannot handle problems with unknown systems due to IP protections. To overcome this problem, the proposed method utilizes the artificial neural network (ANN) to create trainable behavioral macromodels of the unknown circuits based on the port currents and port voltages. The obtained macromodel is then coupled with DGTD that describes the behavior of electromagnetic subsystem to form equations …

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Global Adjoint Sensitivity Analysis Of Coupled Coils Using Parameterized Model Order Reduction, Luca De Camillis, Giulio Antonini, Francesco Ferranti, Albert E. Ruehli Sep 2016

Global Adjoint Sensitivity Analysis Of Coupled Coils Using Parameterized Model Order Reduction, Luca De Camillis, Giulio Antonini, Francesco Ferranti, Albert E. Ruehli

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a parameterized model order reduction technique for efficient global sensitivity analysis of coupled coils. It is based on the use of parameterized models for the electromagnetic matrices and the Krylov matrices of the original and corresponding adjoint systems, and congruence transformations. Numerical results confirm the efficiency and accuracy of the proposed method for global sensitivity analysis over the complete design space of interest.

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Approximated Proportionate Affine Projection Algorithms For Block-Sparse Identification, Felix Albu, Jianming Liu, Steven L. Grant Sep 2016

Approximated Proportionate Affine Projection Algorithms For Block-Sparse Identification, Felix Albu, Jianming Liu, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper two block-sparse approximated memory improved proportionate affine projection algorithm are proposed for block sparse system identification. An approximation is used for a recently proposed family of block-sparse proportionate affine projection algorithms. It is shown that the proposed algorithms have close convergence performance to the original ones, and they are less numerically complex. An investigation of the influence of their parameters is also presented.

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Time-Domain Partial Element Equivalent Circuit Solver Including Non-Linear Magnetic Materials, Daniele Romano, Giulio Antonini, Albert E. Ruehli Sep 2016

Time-Domain Partial Element Equivalent Circuit Solver Including Non-Linear Magnetic Materials, Daniele Romano, Giulio Antonini, Albert E. Ruehli

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a novel partial element equivalent circuit formulation to handle 3-D non-linear problems. Since the displacement currents are taken into account, the proposed formulation is not restricted to low-frequency applications, although the propagation delays are neglected. The non-linear problem is solved by means of the Newton-Raphson algorithm. Special care is taken in order to analytically compute the Jacobian of the problem. Furthermore, an adaptive setting of the time step is adopted in the transient analysis allowing to maintain the size of the time step as large as possible while preserving the accuracy. Computed results for a closed magnetic …

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Selective Body Biasing For Post-Silicon Tuning Of Sub-Threshold Designs: A Semi-Infinite Programming Approach With Incremental Hypercubic Sampling, Hui Geng, Jianming Liu, Jinglan Liu, Pei Wen Luo, Liang Chia Cheng, Steven L. Grant, Yiyu Shi Sep 2016

Selective Body Biasing For Post-Silicon Tuning Of Sub-Threshold Designs: A Semi-Infinite Programming Approach With Incremental Hypercubic Sampling, Hui Geng, Jianming Liu, Jinglan Liu, Pei Wen Luo, Liang Chia Cheng, Steven L. Grant, Yiyu Shi

Electrical and Computer Engineering Faculty Research & Creative Works

Sub-threshold designs have become a popular option in many energies constrained applications. However, a major bottleneck for these designs is the challenge in attaining timing closure. Most of the paths in sub-threshold designs can become critical paths due to the purely random process variation on threshold voltage, which exponentially impacts the gate delay. In order to address timing violations caused by process variation, post-silicon tuning is widely used through body biasing technology, which incurs heavy power and area overhead. Therefore, it is imperative to select only a small group of the gates with body biasing for post-silicon-tuning. In this paper, …

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X-Ray Absorption Fine Structure Of Zno Thin Film On Si And Sapphire Grown By Mocvd, Jieping Xin, Chieh Miao Chang, Chih Han Hsueh, Jyh Fu Lee, Jin Ming Chen, Hao Hsiung Lin, Na Lu, Ian T. Ferguson, Yongjing Guan, Lingyu Wan, Qingyi Yang, Zhe Chuan Feng Aug 2016

X-Ray Absorption Fine Structure Of Zno Thin Film On Si And Sapphire Grown By Mocvd, Jieping Xin, Chieh Miao Chang, Chih Han Hsueh, Jyh Fu Lee, Jin Ming Chen, Hao Hsiung Lin, Na Lu, Ian T. Ferguson, Yongjing Guan, Lingyu Wan, Qingyi Yang, Zhe Chuan Feng

Electrical and Computer Engineering Faculty Research & Creative Works

X-ray absorption fine structure has been used to study the electronic structure, and bond length of ZnO thin films grown on sapphire and Si substrates by metalorganic chemical vapor deposition. X-ray absorption near edge structure (XANES) of O and Zn K-edge were shown, and a detailed analysis of extended x-ray absorption fine structure (EXAFS) of Zn K-edge indicates that difference substrates result in the contraction of Zn-O bond length.

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A New Wiretap Channel Model And Its Strong Secrecy Capacity, Mohamed Nafea, Aylin Yener Aug 2016

A New Wiretap Channel Model And Its Strong Secrecy Capacity, Mohamed Nafea, Aylin Yener

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a new wiretap channel (WTC) model with a discrete memoryless (DM) main channel and a wiretapper who noiselessly observes a fixed portion, of her choice, of the transmitted symbols, while observing the remaining transmitted symbols through another DM channel (DMC), is considered. The strong secrecy capacity of the model is identified. The achievability is established using the output statistics of random binning framework which exploits the duality between source and channel coding problems. The converse is derived by upper bounding the secrecy capacity of an equivalent model with the secrecy capacity of a DM-WTC. This result generalizes …

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The Multiple Access Wiretap Channel Ii With A Noisy Main Channel, Mohamed Nafea, Aylin Yener Aug 2016

The Multiple Access Wiretap Channel Ii With A Noisy Main Channel, Mohamed Nafea, Aylin Yener

Electrical and Computer Engineering Faculty Research & Creative Works

A two-transmitter multiple access wiretap channel II (MAC-WT-II) with a discrete memoryless (DM) main channel is investigated. Two models for the wiretapper, who chooses a fixed-length subset of the channel uses and observes erasures outside this subset, are proposed. In the first model, in each position of the subset, the wiretapper noiselessly observes either the first or the second user's symbol, while in the second model, the wiretapper observes a noiseless superposition of the two symbols. Achievable strong secrecy rate regions for the two models are derived. The achievability is established by solving a dual secret key agreement problem in …

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A Fast Filtering Block-Sparse Proportionate Affine Projection Sign Algorithm, Felix Albu, Jianming Liu, Steven L. Grant Aug 2016

A Fast Filtering Block-Sparse Proportionate Affine Projection Sign Algorithm, Felix Albu, Jianming Liu, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a new proportionate affine projection sign algorithm for block-sparse identification using a fast recursive filtering procedure and dichotomous coordinate descent iterations is proposed. It is shown that the proposed algorithm is a good candidate for network echo cancellation systems operating under impulsive environments.

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Free Deterministic Equivalents For The Analysis Of Mimo Multiple Access Channel, An An Lu, Xiqi Gao, Chengshan Xiao Aug 2016

Free Deterministic Equivalents For The Analysis Of Mimo Multiple Access Channel, An An Lu, Xiqi Gao, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a free deterministic equivalent is proposed for the capacity analysis of the multi-input multi-output (MIMO) multiple access channel (MAC) with a more general channel model compared to previous works. In particular, a MIMO MAC with one base station (BS) equipped with several distributed antenna sets is considered. Each link between a user and a BS antenna set forms a jointly correlated Rician fading channel. The analysis is based on operator-valued free probability theory, which broadens the range of applicability of free probability techniques tremendously. By replacing independent Gaussian random matrices with operator-valued random variables satisfying certain operator-valued …

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