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Articles 31 - 49 of 49
Full-Text Articles in Engineering
A Study Of Single Scattering Of Scatterer At Various Orientation Angles With Equivalence Principle Algorithm, Chan Fai Lum, Hong Tat Ewe, Fu-Xin, Li (Lijun) Jun Jiang
A Study Of Single Scattering Of Scatterer At Various Orientation Angles With Equivalence Principle Algorithm, Chan Fai Lum, Hong Tat Ewe, Fu-Xin, Li (Lijun) Jun Jiang
Electrical and Computer Engineering Faculty Research & Creative Works
It is common that spherical scatterers are used to represent air bubbles or brine inclusions embedded in the snow or sea ice layer. This physical configuration is then solved using radiative transfer theory to obtain backscattering coefficient from the snow or sea ice layer. With the advent of new techniques in computational electromagnetics, the typical theoretical model of single layer of snow or sea ice can be easily extended to consider types of scatterers which are of other shapes or irregular shapes. A computational electromagnetic method based on equivalence principle algorithm can be incorporated into existing theoretical model to calculate …
Free-Hand Scanning And Imaging, Joseph T. Case, Mohammad Tayeb Ahmad Ghasr, R. Zoughi
Free-Hand Scanning And Imaging, Joseph T. Case, Mohammad Tayeb Ahmad Ghasr, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
Wideband synthetic aperture radar (SAR) imaging. A probe transmits a signal through its aperture incident to an object located in a medium of interest remotely from the probe. The probe receives through the aperture a plurality of nonuniformly sampled reflected signals from the object as the probe moves in a measurement plane located a predetermined distance from the object. A processor executes a SAR-based reconstruction algorithm to generate an image.
An Equivalent Circuit Model For Graphene-Based Terahertz Antenna Using The Peec Method, Ying S. Cao, Li (Lijun) Jun Jiang, Albert E. Ruehli
An Equivalent Circuit Model For Graphene-Based Terahertz Antenna Using The Peec Method, Ying S. Cao, Li (Lijun) Jun Jiang, Albert E. Ruehli
Electrical and Computer Engineering Faculty Research & Creative Works
The electromagnetic (EM) characterization of graphene under general EM environments is becoming of interest in the engineering and scientific research fields. However, its numerical modeling process is extremely cost prohibitive due to the huge contrast between its thickness and other dimensions. In this work, for the first time, the EM features of graphene are characterized by a circuit model through the partial element equivalent circuit (PEEC) method. The atomically thick graphene is equivalently replaced by an impedance boundary condition. After incorporating the PEEC method, a novel surface conductivity circuit model is derived for graphene. A physical resistor and inductor are …
A Frequency-Independent Method For Computing The Physical Optics-Based Electromagnetic Fields Scattered From A Hyperbolic Surface, Yu Mao Wu, Weng Cho Chew, Ya Qiu Jin, Li (Lijun) Jun Jiang, Hongxia Ye, Wei E.I. Sha
A Frequency-Independent Method For Computing The Physical Optics-Based Electromagnetic Fields Scattered From A Hyperbolic Surface, Yu Mao Wu, Weng Cho Chew, Ya Qiu Jin, Li (Lijun) Jun Jiang, Hongxia Ye, Wei E.I. Sha
Electrical and Computer Engineering Faculty Research & Creative Works
In this communication, we propose a frequency-independent approach, the numerical steepest descent path (NSDP) method, for computing the physical optics scattered electromagnetic field on the quadratic hyperbolic surface. Due to the highly oscillatory nature of the physical optics integral, the proposed method relies on deforming the integration path of the integral into the NSDP on the complex plane. Numerical results for the PO-based EM fields from the hyperbolic surface illustrate that the proposed NSDP method is frequency independent in computational cost and error controllable in accuracy.
Comparison Of Binary And Multi-Level Logic Electronics For Embedded Systems, Shirly M. Damti, Steve Eugene Watkins, R. Joe Stanley
Comparison Of Binary And Multi-Level Logic Electronics For Embedded Systems, Shirly M. Damti, Steve Eugene Watkins, R. Joe Stanley
Electrical and Computer Engineering Faculty Research & Creative Works
Embedded systems are dependent on low-power, miniaturized instrumentation. Comparator circuits are common elements in applications for digital threshold detection. A multi-level, memory-based logic approach is in development that offers potential benefits in power usage and size with respect to traditional binary logic systems. Basic 4-bit operations with CMOS gates and comparators are chosen to compare circuit implementations of binary structures and quaternary equivalents. Circuit layouts and functional operation are presented. In particular, power characteristics and transistor count are examined. The potential for improved embedded systems based on the multilevel, memory-based logic is discussed.
A Dgtd Scheme For Modeling The Radiated Emission From Duts In Shielding Enclosures Using Near Electric Field Only, Ping Li, Yifei Shi, Li (Lijun) Jun Jiang, Hakan Baǧci
A Dgtd Scheme For Modeling The Radiated Emission From Duts In Shielding Enclosures Using Near Electric Field Only, Ping Li, Yifei Shi, Li (Lijun) Jun Jiang, Hakan Baǧci
Electrical and Computer Engineering Faculty Research & Creative Works
To meet the electromagnetic interference regulation, the radiated emission from device under test such as electronic devices must be carefully manipulated and accurately characterized. Instead of resorting to the direct far-field measurement, in this paper, a novel approach is proposed to model the radiated emission from electronic devices placed in shielding enclosures by using the near electric field only. Based on the Schelkkunoff's equivalence principle and Raleigh-Carson reciprocity theorem, only the tangential components of the electric field over the ventilation slots and apertures of the shielding enclosure are sufficient to obtain the radiated emissions outside the shielding box if the …
A Fast Time-Domain Em-Tcad Coupled Simulation Framework Via Matrix Exponential With Stiffness Reduction, Quan Chen, Wim Schoenmaker, Shih Hung Weng, Chung Kuan Cheng, Guan Hua Chen, Li (Lijun) Jun Jiang, Ngai Wong
A Fast Time-Domain Em-Tcad Coupled Simulation Framework Via Matrix Exponential With Stiffness Reduction, Quan Chen, Wim Schoenmaker, Shih Hung Weng, Chung Kuan Cheng, Guan Hua Chen, Li (Lijun) Jun Jiang, Ngai Wong
Electrical and Computer Engineering Faculty Research & Creative Works
We present a fast time-domain multiphysics simulation framework that combines full-wave electromagnetism (EM) and carrier transport in semiconductor devices (technology computer-aided design (TCAD)) for radio frequency (RF) and mixed-signal modules. The proposed framework features a division of linear and nonlinear components in the EM-TCAD coupled system. The linear portion is extracted and handled independently with high efficiency by a matrix exponential approach assisted with Krylov subspace method. The nonlinear component is treated by ordinary Newton's method yet with a much sparser Jacobian matrix that leads to substantial speedup in solving the linear system of equations. More convenient error management and …
Strain Monitoring Of Bismaleimide Composites Using Embedded Microcavity Sensor, Amardeep Kaur, Sudharshan Anandan, Lei Yuan, Steve Eugene Watkins, K. Chandrashekhara, Hai Xiao, Nam Phan
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 …
Application Of Generalized Snoek's Law Over A Finite Frequency Range: A Case Study, Konstantin N. Rozanov, Marina Y. Koledintseva
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
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 …
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
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
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
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 …
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
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 …
Performance Enhancement Of Equivalence Principle Algorithm, Xin Fu, Li (Lijun) Jun Jiang, Zu Hui Ma, Shi Quan He
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.
Transient Analysis Of Lumped Circuit Networks-Loaded Thin Wires By Dgtd Method, P. Li, Y. Shi, Lijun Jiang, H. Bagci
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 …
A Novel Relaxed Hierarchical Equivalent Source Algorithm (Rhesa) For Electromagnetic Scattering Analysis Of Dielectric Objects, Xin Fu, Li (Lijun) Jun Jiang, Hong Tat Ewe
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.
Pre-College Engineering Activities With Electronic Circuits (Work-In-Progress), Steve Eugene Watkins
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.
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
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 …