Engineering Commons^™

Strain Monitoring Of Bismaleimide Composites Using Embedded Microcavity Sensor, Amardeep Kaur, Sudharshan Anandan, Lei Yuan, Steve Eugene Watkins, K. Chandrashekhara, Hai Xiao, Nam Phan

Electrical and Computer Engineering Faculty Research & Creative Works

A type of extrinsic Fabry-Perot interferometer (EFPI) fiber optic sensor, i.e., the microcavity strain sensor, is demonstrated for embedded, high-temperature applications. The sensor is fabricated using a femtosecond (fs) laser. The fs-laser-based fabrication makes the sensor thermally stable to sustain operating temperatures as high as 800 °C. The sensor has low sensitivity toward the temperature as compared to its response toward the applied strain. The performance of the EFPI sensor is tested in an embedded application. The host material is carbon fiber/bismaleimide (BMI) composite laminate that offer thermally stable characteristics at high ambient temperatures. The sensor exhibits highly linear response …

An Optimized Proportionate Adaptive Algorithm For Sparse System Identification, Silviu Ciochina, Constantin Paleologu, Jacob Benesty, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

Proportionate-type adaptive algorithms are commonly used for the identification of sparse impulse responses, like in network and acoustic echo cancellation. In this paper, we propose an optimized proportionate LMS adaptive filter in the context of a state variable model. The algorithm follows an optimization criterion based on the minimization of the system misalignment and uses an iterative procedure for computing the proportionate factors. Consequently, it achieves a proper compromise between the performance criteria, i.e., fast convergence/tracking and low mis adjustment. Simulations performed in the context of sparse system identification indicate the good behavior of the proposed algorithm.

Application Of Generalized Snoek's Law Over A Finite Frequency Range: A Case Study, Konstantin N. Rozanov, Marina Y. Koledintseva

Electrical and Computer Engineering Faculty Research & Creative Works

Generalized Snoek's law proposed in an integral form by Acher and coauthors is a useful tool for investigation of high-frequency properties of magnetic materials. This integral law referred to as Acher's law allows for evaluating the ultimate performance of RF and microwave devices which employ magnetic materials. It may also be helpful in obtaining useful information on the structure and morphology of the materials. The key factor in practical application of Acher's law is an opportunity to employ either measured or calculated data available over a finite frequency range. The paper uses simple calculations to check the applicability of Acher's …

Artificial Perfect Electric Conductor-Perfect Magnetic Conductor Anisotropic Metasurface For Generating Orbital Angular Momentum Of Microwave With Nearly Perfect Conversion Efficiency, Menglin L.N. Chen, Li (Lijun) Jun Jiang, Wei E.I. Sha

Electrical and Computer Engineering Faculty Research & Creative Works

Orbital angular momentum (OAM) is a promising degree of freedom for fundamental studies in electromagnetics and quantum mechanics. The unlimited state space of OAM shows a great potential to enhance channel capacities of classical and quantum communications. By exploring the Pancharatnam-Berry phase concept and engineering anisotropic scatterers in a metasurface with spatially varying orientations, a plane wave with zero OAM can be converted to a vortex beam carrying nonzero OAM. In this paper, we proposed two types of novel perfect electric conductor-perfect magnetic conductor anisotropic metasurfaces. One is composed of azimuthally continuous loops and the other is constructed by azimuthally …

The Structural Properties Of Ingan Alloys And The Interdependence On The Thermoelectric Behavior, Bahadir Kucukgok, Xuewang Wu, Xiaojia Wang, Zhiqiang Liu, Ian T. Ferguson, Na Lu

Electrical and Computer Engineering Faculty Research & Creative Works

The III-Nitrides are promising candidate for high efficiency thermoelectric (TE) materials and devices due to their unique features which includes high thermal stability. A systematic study of the room temperature TE properties of metalorganic chemical vapor deposition grown InxGa1-xN were investigated for x = 0.07 to 0.24. This paper investigated the role of indium composition on the TE properties of InGaN alloys in particular the structural properties for homogenous material that did not show significant phase separation. The highest Seebeck and power factor values of 507 μV K^-1 and 21.84 x 10^-4 Wm^-1K^-1 were observed, …

Impurity Resonant States P-Type Doping In Wide-Band-Gap Nitrides, Zhiqiang Liu, Xiaoyan Yi, Zhiguo Yu, Gongdong Yuan, Yang Liu, Junxi Wang, Jinmin Li, Na Lu, Ian Ferguson, Yong Zhang

Electrical and Computer Engineering Faculty Research & Creative Works

In this work, a new strategy for achieving efficient p-type doping in high bandgap nitride semiconductors to overcome the fundamental issue of high activation energy has been proposed and investigated theoretically and demonstrated experimentally. Specifically, in an Al x Ga 1-x N/GaN superlattice structure, by modulation doping of Mg in the Al x Ga 1-x N barriers, high concentration of holes is generated throughout the material. A hole concentration as high as 1.1 x 10 18 cm -3 has been achieved, which is about one order of magnitude higher than that typically achievable by direct doping GaN. Results from first-principal …

Nonlinearity Of Digital I/Os And Its Behaviour Modeling, He Ming Yao, Huan Huan Zhang, Hui Chun Yu, Xing Yun Luo, Bin Li, Hua Sheng Ren, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Due to the rising signal speed in today's integrated circuits (ICs), the digital input/output (I/O) device modeling becomes a very serious challenge. However, its nonlinearity issue was even less addressed. But for accurate EMC and EMI characterizations, the I/O nonlinearity could become a source of unexpected EMC and EMI troubles in the high-speed system. In this paper, we analyze the nonlinearity of high-speed drivers and loads under the influence of various parameters, such as the rising and falling times, data and clock duty cycle distortion (DCD), signal skew, balance of the circuit, etc. Further based on the spectrum property of …

Compact Nonlinear Yagi-Uda Nanoantennas, 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

Nanoantennas have demonstrated unprecedented capabilities for manipulating the intensity and direction of light emission over a broad frequency range. The directional beam steering offered by nanoantennas has important applications in areas including microscopy, spectroscopy, quantum computing, and on-chip optical communication. Although both the physical principles and experimental realizations of directional linear nanoantennas has become increasingly mature, angular control of nonlinear radiation using nanoantennas has not been explored yet. Here we propose a novel concept of nonlinear Yagi-Uda nanoantenna to direct second harmonic radiation from a metallic nanosphere. By carefully tuning the spacing and dimensions of two lossless dielectric elements, which …

Staves: Speedy Tensor-Aided Volterra-Based Electronic Simulator, Haotian Liu, Xiaoyan Y.Z. Xiong, Kim Batselier, Lijun Jiang, Luca Daniel, Ngai Wong

Electrical and Computer Engineering Faculty Research & Creative Works

Volterra series is a powerful tool for black-box macro-modeling of nonlinear devices. However, the exponential complexity growth in storing and evaluating higher order Volterra kernels has limited so far its employment on complex practical applications. On the other hand, tensors are a higher order generalization of matrices that can naturally and efficiently capture multi-dimensional data. Significant computational savings can often be achieved when the appropriate low-rank tensor decomposition is available. In this paper we exploit a strong link between tensors and frequency-domain Volterra kernels in modeling nonlinear systems. Based on such link we have developed a technique called speedy tensor-aided …

1-Bit Compressed Sensing Based Framework For Built-In Resonance Frequency Prediction Using On-Chip Noise Sensors, Tao Wang, Jinglan Liu, Cheng Zhuo, Yiyu Shi

Electrical and Computer Engineering Faculty Research & Creative Works

Significant noise will occur when the load currents of a chip contain frequency components that are close to its resonance frequency, which is mainly decided by power delivery network (PDN) capacitance and package inductance. Yet with technology scaling, the wire parasitic capacitance, which suffers from large process variations, starts to become a dominant contributor in the PDN capacitance, leading to a large resonance frequency variation across dies. It is thus important to know the resonance frequency of individual chips to effectively avoid resonance noise at runtime. Existing methods are mostly based on frequency sweeping, which are too expensive to apply …

Pre-College Engineering Activities With Electronic Circuits (Work-In-Progress), Steve Eugene Watkins

Electrical and Computer Engineering Faculty Research & Creative Works

Projects involving engineering experimentation, design, and measurement can be effective content for pre-college STEM outreach. Such applications-oriented activities can promote literacy and interest in technical topics and careers and have the added benefit of showing the relevance of science and mathematics. Exposure to electrical engineering concepts is discussed using the 555 timer integrated circuit. This low-cost device can be used for modular activities involving the production of light, sound, and motion. Specific projects are presented that are appropriate for pre-college students from 9th-grade through 12th-grade.

A Novel Relaxed Hierarchical Equivalent Source Algorithm (Rhesa) For Electromagnetic Scattering Analysis Of Dielectric Objects, Xin Fu, Li (Lijun) Jun Jiang, Hong Tat Ewe

Electrical and Computer Engineering Faculty Research & Creative Works

A novel relaxed hierarchical algorithm based on the surface equivalence principle for the volume integral equations (VIEs) is proposed in this work. The equivalent sources residing on relaxed spherical equivalence surfaces are established by exact integral formulations. The equivalence surfaces are exploited hierarchically to accelerate matrix–vector product in iterative solutions for the VIEs. The computation time and memory cost complexity of the proposed algorithm for dielectric scatters scale as O(N4/3) and O(N) , respectively. Numerical examples validate the accuracy and capability of the proposed algorithm.

Performance Enhancement Of Equivalence Principle Algorithm, Xin Fu, Li (Lijun) Jun Jiang, Zu Hui Ma, Shi Quan He

Electrical and Computer Engineering Faculty Research & Creative Works

The conventional equivalence principle algorithm (EPA) exploits cubical surfaces to support equivalent sources. However, it introduces strong discontinuities due to sharp edges and corners. In this letter, a spherical surface is employed as the equivalence surface to avoid singularities from nonsmoothness. To achieve better accuracy, the meshless sampling scheme is used for integral operators on the spherical equivalence surface. The numerical examples are provided to validate the performance enhancement of EPA through the proposed method.

Mitigation Emission Strategy Based On Resonances From A Power Inverter System In Electric Vehicles, L. Zhai, Xinyu Zhang, Natalia G. Bondarenko, David Loken, Thomas Van Doren, Daryl G. Beetner

Electrical and Computer Engineering Faculty Research & Creative Works

Large dv/dt and di/dt outputs of power devices in the DC-fed motor power inverter can generate conducted and/or radiated emissions through parasitics that interfere with low voltage electric systems in electric vehicles (EVs) and nearby vehicles. The electromagnetic interference (EMI) filters, ferrite chokes, and shielding added in the product process based on the "black box" approach can reduce the emission levels in a specific frequency range. However, these countermeasures may also introduce an unexpected increase in EMI noises in other frequency ranges due to added capacitances and inductances in filters resonating with elements of the power inverter, and even increase …

Stress-Induced Birefringence And Fabrication Of In-Fiber Polarization Devices By Controlled Femtosecond Laser Irradiations, Lei Yuan, Baokai Cheng, Jie Huang, Jie Liu, Hanzheng Wang, Xinwei Lan, Hai Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

Optical birefringence was created in a single-mode fiber by introducing a series of symmetric cuboid stress rods on both sides of the fiber core along the fiber axis using a femtosecond laser. The stress-induced birefringence was estimated to be 2.4 x 10^-4 at the wavelength of 1550 nm. By adding the desired numbers of stressed rods, an in-fiber quarter waveplate was fabricated with a insertion loss of 0.19 dB. The stressinduced birefringence was further explored to fabricate in-fiber polarizers based on the polarization-dependent long-period fiber grating (LPFG) structure. A polarization extinction ratio of more than 20 dB was observed …

Transient Analysis Of Lumped Circuit Networks-Loaded Thin Wires By Dgtd Method, P. Li, Y. Shi, Lijun Jiang, H. Bagci

Electrical and Computer Engineering Faculty Research & Creative Works

With the purpose of avoiding very fine mesh cells in the proximity of a thin wire, the modified telegrapher’s equations (MTEs) are employed to describe the thin wire voltage and current distributions, which consequently results in reduced number of unknowns and augmented Courant–Friedrichs–Lewy (CFL) number. As hyperbolic systems, both the MTEs and the Maxwell’s equations are solved by the discontinuous Galerkin time-domain (DGTD) method. In realistic situations, the thin wires could be either driven or loaded by circuit networks. The thin wire–circuit interface performs as a boundary condition for the thin wire solver, where the thin wire voltage and current …

Co-Doping Of Magnesium With Indium In Nitrides: First Principle Calculation And Experiment, Zhiqiang Liu, Binglei Fu, Xiaoyan Yi, Guodong Yuan, Junxi Wang, Jinmin Li, Luna, Ian Ferguson

Electrical and Computer Engineering Faculty Research & Creative Works

In this work, an effective strategy for achieving efficient p-type doping in wide bandgap nitride semiconductors was proposed to overcome the fundamental issue of high activation energy. We demonstrated that a hole concentration as high as 1.4 x 1018 cm-3 could been achieved through In-Mg co-doping. The electronic structure of the system and the formation energy of impurity were analyzed via first principal calculation to clarify the underlying physics and the ambiguity in understanding of the origin of the high hole concentration. Our results indicated that the original valence band maximum of the host materials could be modified, thus improving …

Electrostatically-Actuated 4h-Sic In-Plane And Out-Of-Plane High Frequency Mems Resonator, Allen V. Lim, Tutku Karacolak, Jheng Yi Jiang, Chih Fang Huang, Feng Zhao

Electrical and Computer Engineering Faculty Research & Creative Works

As a wide bandgap and single crystalline semiconductor, 4H-polytype silicon carbide (4H-SiC) is an excellent material choice for devices operating in harsh environments of high temperature, high pressure, radiation, chemical and biomedical, etc. In this letter, an electrostatically actuated 4H-SiC micro resonator was fabricated by dopant-selective photoelectrochemical etching of n-p-n homoepitaxial structure. Resonant frequencies of 3.463 MHz (out-of-plane) and 16.9 MHz (in-plane) were attained, and they are in good agreement with theoretical calculation. To the best of our knowledge, these frequencies are the highest values ever reported from single crystalline 4H-SiC MEMS resonators.

Effects Of Electrode Materials On Charge Conduction Mechanisms Of Memory Device Based On Natural Aloe Vera, Zhe Xi Lim, Sasidharan Sreenivasan, Yew Hoong Wong, Feng Zhao, Kuan Yew Cheong

Electrical and Computer Engineering Faculty Research & Creative Works

Resistive switching behaviors in Aloe vera films are being explored for nonvolatile memory applications. A simple structure in which the Aloe vera films sandwiched in between a top and bottom electrode are used. The switching behaviors of the devices in which the Aloe vera film is dried at different temperatures and the roles of top electrode materials (Al and Ag) are investigated. Current density-voltage measurements reveal that filamentary conduction is the dominant conduction process inducing resistive switching characteristics in Aloe vera films. Device with Al-Top electrode requires a forming voltage higher than devices with Ag-Top electrode, due to the tendency …

Novel Time Domain Integral Equation Method Hybridized With The Macromodels Of Circuits, Huan Huan Zhang, He Ming Yao, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

This work presents a novel transient field-circuit simulation method based on the time-domain integral equation (TDIE) and circuit macromodels. The traditional field-circuit simulation method constructs the Kirchoff's equations for lumped circuits with SPICE models, but they cannot handle problems with unknown circuit structures. The proposed method creates parametric macromodels to represent the port constitutive relations of the unknown circuits. Then the obtained macromodel is coupled with TDIE to enable the transient field-circuit cosimulation. Numerical examples are given to demonstrate the validity of the proposed method. The proposed method is targeted to solve unknown I/O modeling issues in general signal integrity …

Broadband High Gain Siw Ring Slot Antenna, Zhi Shen, Kirti Dhwaj, Hanseung Lee, Tatsuo Itoh, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

The slot antenna backed by the substrate integrated waveguide (SIW) cavity usually demonstrates very narrow bandwidth. In this paper, we extend the interpretation to our original dual mode SIW ring slot antenna so that a broadband radiation property based on the TE102 mode is unveiled for the first time. Through the experimental verification, over 12% bandwidth is conveniently achieved. The realized gain reaches over 7 dB. Its broadband working principle is studied in details. Simulated and measured data are both presented to verify the proposed ideas.

Dgtd Analysis Of Electromagnetic Scattering From Penetrable Conductive Objects With Ibc, Ping Li, Yifei Shi, Li (Lijun) Jun Jiang, Hakan Bagci

Electrical and Computer Engineering Faculty Research & Creative Works

To avoid straightforward volumetric discretization, a discontinuous Galerkin time-domain (DGTD) method integrated with the impedance boundary condition (IBC) is presented in this paper to analyze the scattering from objects with finite conductivity. Two situations are considered. 1) The skin depth is smaller than the thickness of the conductive volume. 2) The skin depth is larger than the thickness of a thin conductive sheet. For the first situation, a surface impedance boundary condition (SIBC) is employed, wherein the surface impedance usually exhibits a complex relation with the frequency. To incorporate the SIBC into DGTD, the surface impedance is first approximated by …

A Low Complexity Reweighted Proportionate Affine Projection Algorithm With Memory And Row Action Projection, Jianming Liu, Steven L. Grant, Jacob Benesty

Electrical and Computer Engineering Faculty Research & Creative Works

A new reweighted proportionate affine projection algorithm (RPAPA) with memory and row action projection (MRAP) is proposed in this paper. The reweighted PAPA is derived from a family of sparseness measures, which demonstrate performance similar to mu-law and the l0 norm PAPA but with lower computational complexity. The sparseness of the channel is taken into account to improve the performance for dispersive system identification. Meanwhile, the memory of the filter's coefficients is combined with row action projections (RAP) to significantly reduce computational complexity. Simulation results demonstrate that the proposed RPAPA MRAP algorithm outperforms both the affine projection algorithm (APA) and …

An Overview On Optimized Nlms Algorithms For Acoustic Echo Cancellation, Constantin Paleologu, Silviu Ciochină, Jacob Benesty, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

Acoustic echo cancellation represents one of the most challenging system identification problems. The most used adaptive filter in this application is the popular normalized least mean square (NLMS) algorithm, which has to address the classical compromise between fast convergence/tracking and low mis adjustment. In order to meet these conflicting requirements, the step-size of this algorithm needs to be controlled. Inspired by the pioneering work of Prof. E. Hänsler and his collaborators on this fundamental topic, we present in this paper several solutions to control the adaptation of the NLMS adaptive filter. The developed algorithms are "non-parametric" in nature, i.e., they …

Fast Random Walk Based Capacitance Extraction For The 3-D Ic Structures With Cylindrical Inter-Tier-Vias, Chao Zhang, Wenjian Yu, Qing Wang, Yiyu Shi

Electrical and Computer Engineering Faculty Research & Creative Works

3-D integrated circuits (3-D ICs) make use of the vertical dimension for smaller footprint, higher speed, lower power consumption, and better timing performance. In 3-D ICs, the inter-Tier-via (ITV) is a critical enabling technique because it forms vertical signal and power paths. Accordingly, it is imperative to accurately and efficiently extract the electrostatic capacitances of ITVs using field solvers. Unfortunately, the cylindrical via shape presents major challenges to most of the existing methods. To address this issue, we develop a novel floating random walk (FRW) method by rotating the transition cube to suit the cylindrical surface, devising a special space …

Manipulating Electromagnetic Local Density Of States By Graphene Plasmonics, Yongpin P. Chen, Wei E.I. Sha, Li (Lijun) Jun Jiang, Jun Hu

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic local density of states (ELDOS) counts the number of electromagnetic modes at a spatial point where a particle (atom, molecule, and quantum dot) spontaneously emits electromagnetic waves. ELDOS can be interpreted as a density of vacuum fluctuations of electromagnetic fields. Moreover, ELDOS is essential to control spontaneous decay rate (SDR) of particles; and thus plays a critical role in modern optical and quantum devices. Having a great degree of freedom to tune permittivity, graphene is an emerging building block to manipulate the ELDOS. In this work, we study SDR of a particle near a metallic split-ring resonator, which is …

Capillary Wall Coupled Whispering Gallery Mode Microresonator, Hai Xiao, Wang Hanzheng

Electrical and Computer Engineering Faculty Research & Creative Works

A microresonator structure comprises a waveguide and a microsphere. The waveguide is of elongated cylindrical shape and includes a first section of optical transmission material and a cavity section axially aligned with the first section. The cavity section includes a first cavity and a second cavity. The first cavity is adjacent to the first section and includes a first sidewall of optical transmission material with an inner surface that tapers inward to an apex positioned adjacent to the first section. The second cavity is positioned adjacent to the first cavity of hollow cylindrical shape and includes a circumferential second sidewall …

Real-Time Supervised Detection Of Pink Areas In Dermoscopic Images Of Melanoma: Importance Of Color Shades, Texture And Location, Ravneet Kaur, P. P. Albano, Justin G. Cole, Jason R. Hagerty, Robert W. Leander, Randy Hays Moss, William V. Stoecker

Electrical and Computer Engineering Faculty Research & Creative Works

Background/Purpose: Early detection of malignant melanoma is an important public health challenge. In the USA, dermatologists are seeing more melanomas at an early stage, before classic melanoma features have become apparent. Pink color is a feature of these early melanomas. If rapid and accurate automatic detection of pink color in these melanomas could be accomplished, there could be significant public health benefits.

Methods: Detection of three shades of pink (light pink, dark pink, and orange pink) was accomplished using color analysis techniques in five color planes (red, green, blue, hue, and saturation). Color shade analysis was performed using a logistic …

Hierarchical Equivalent Source Algorithm Based On Relaxed Spherical Equivalence Surface, Xin Fu, Li (Lijun) Jun Jiang, Hong Tat Ewe

Electrical and Computer Engineering Faculty Research & Creative Works

A new hierarchical algorithm based on surface equivalence principle is proposed in this work. The equivalent sources residing on relaxed spherical equivalence surfaces are computed by closed-form integral operators rather than numerical approximations. Consequently, a hierarchical algorithm based on oct-tree is straightforward to implement. Numerical examples validate the accuracy and capability of the proposed algorithm.

A Supercell Based Dual Beam Dielectric Grating Antenna For 60 Ghz Application, Zi Long Ma, Chi Hou Chan, Kung Bo Ng, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A dual-beam dielectric grating antenna based on the supercell (SC) concept is presented in this paper. Theoretical analysis shows that with the perturbations of different unit cells (UC), two space harmonic modes (m = -1 and m = -2) are excited (above the air line) in the dispersion diagram of the supercell in a certain frequency range. This phenomenon leads to the generation of two radiation beams in the far-field region. At the operating frequency where the phase constants β-1 =β in symmetric directions. In addition, a symmetric SC is proposed and carefully designed to achieve equal performance (beam width …