Electrical and Computer Engineering Commons^™

Emi From Cavity Modes Of Shielding Enclosures-Fdtd Modeling And Measurements, Min Li, Joe Nuebel, James L. Drewniak, Richard E. Dubroff, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic interference (EMI) from slots and apertures resulting from coupling of interior sources through enclosure cavity modes in a rectangular test enclosure is reported herein. EMI from a specially designed test enclosure with slots or apertures excited by interior sources was studied experimentally and with finite-difference time-domain (FDTD) modeling. The measurements and FDTD modeling agree well. The results indicate that radiation at cavity mode resonances through slots and apertures of nonresonant dimensions can be as significant as the radiation at aperture or slot resonances. The agreement between the FDTD modeling and measurements demonstrates the usefulness of FDTD for investigating aspects …

Microwave Near-Field Reflection Property Analysis Of Concrete For Material Content Determination, Karl Joseph Bois, Aaron D. Benally, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

One of the most important parameters associated with concrete is its compressive strength. Currently, there is no reliable nondestructive testing technique that is capable of robust determination of this parameter. Concrete is a heterogeneous mixture composed of water, cement powder, sand (fine aggregate), rocks of various size or grade (coarse aggregate), and air (porosity). Water and cement powder chemically combine into a cement paste binder which, in due curing time (28 days), produces concrete with its specified compressive strength. Compressive strength of concrete is strongly influenced by its water-to-cement (w/c) ratio as well as its coarse aggregate-to-cement (ca/c) ratio. Therefore, …

On The Assessment Of Stability And Patterning Of Speech Movements, Anne Smith, Michael T. Johnson, Clare Mcgillem, Lisa Goffman

Electrical and Computer Engineering Faculty Research and Publications

Speech requires the control of complex movements of orofacial structures to produce dynamic variations in the vocal tract transfer function. The nature of the underlying motor control processes has traditionally been investigated by employing measures of articulatory movements, including movement amplitude, velocity, and duration, at selected points in time. An alternative approach, first used in the study of limb motion, is to examine the entire movement trajectory over time. A new approach to speech movement trajectory analysis was introduced in earlier work from this laboratory. In this method, trajectories from multiple movement sequences are time- and amplitude-normalized, and the STI …

Multilevel Coded Modulation For Unequal Error Protection And Multistage Decoding—Part I: Symmetric Constellations, Robert H. Morelos-Zaragoza, Marc P. C. Fossorier, Shu Lin, Hideki Imai

Faculty Publications

In this paper, theoretical upper bounds and computer simulation results on the error performance of multilevel block coded modulations for unequal error protection (UEP) and multistage decoding are presented. It is shown that nonstandard signal set partitionings and multistage decoding provide excellent UEP capabilities beyond those achievable with conventional coded modulation. The coding scheme is designed in such a way that the most important information bits have a lower error rate than other information bits. The large effective error coefficients, normally associated with standard mapping by set partitioning, are reduced by considering nonstandard partitionings of the underlying signal set. The …

Space/Time/Frequency Methods In Adaptive Radar, Christopher D. Peckham

Dissertations

Radar systems may be processed with various space, time and frequency techniques. Advanced radar systems are required to detect targets in the presence of jamming and clutter. This work studies the application of two types of radar systems.

It is well known that targets moving along-track within a Synthetic Aperture Radar field of view are imaged as defocused objects. The SAR stripmap mode is tuned to stationary ground targets and the mismatch between the SAR processing parameters and the target motion parameters causes the energy to spill over to adjacent image pixels, thus hindering target feature extraction and reducing the …

Multi-User Detection For Multi-Rate Ds/Cdma Systems, Jinwen Ma

Dissertations

Wireless cellular communication is witnessing a rapid growth in market, technology and range of services. Current and future demands for wireless communication services motivate the need for handling multi-media traffic types. In a multimedia communication system, users with different and even time-varying rates and quality of services (QoS) requirements, such as voice, image and data, must be accommodated. The use of Spread Spectrum modulation with Code Division Multiple Access (CDMA) technology is an attractive approach for economical spectrally efficient and high quality cellular and personal communication services. This dissertation explores the technologies of applying different interference cancellation techniques to multi-rate …

Integrated Product And Process Development Methodologies For Environmentally Conscious Electronic Products, Pingtao Yan

Dissertations

This research focuses on integrated product and process development (IPPD) methodologies for environmentally conscious electronic products. After a review of current research issues in the field of product and process development, a generic framework for IPPD is proposed which describes most of the concerned issues formally as constrained optimization problems. These problems may include such optimization objectives as cost, benefit, and environmental impact. Based on this framework, an IPPD methodology is proposed as a systems approach to competitive and environmentally conscious product and process development. A case study on personal computer development is performed illustrating how to apply the methodology …

Data Hiding In Multimedia - Theory And Applications, Mahalingam Ramkumar

Dissertations

Multimedia data hiding or steganography is a means of communication using subliminal channels. The resource for the subliminal communication scheme is the distortion of the original content that can be tolerated. This thesis addresses two main issues of steganographic communication schemes:

1. How does one maximize the distortion introduced without affecting fidelity of the content?

2. How does one efficiently utilize the resource (the distortion introduced) for communicating as many bits of information as possible? In other words, what is a good signaling strategy for the subliminal communication scheme?

Close to optimal solutions for both issues are analyzed. Many techniques …

Editing Mpeg2 Video In Compressed Domain, Ren Egawa

Theses

As MPEG2 becomes the heart of most digital video applications, the need to edit an MPEG2 bitstream video in compressed domain has increased. To realize this need, two major technical issues must be resolved: decoder buffer and segment extraction.

In the decoder buffer issue, the edited stream must ensure that the buffer would not overflow or underfiow as the result of the editing. This thesis invented a mathematical model that could describe the editing task and predict the editing effect on the buffer. Based on this model, the thesis then built a method to edit a stream safely. This method …

Experimental Ion Implantation System For Decaborane Ions, Vijay Babaram

Theses

Future generations of Si technology will require ultra shallow junctions (tens of nm) in the drain and source regions of MOS transistors. Fabrication of such shallow p-type junctions requires implantation of boron at ultra low energies (< 1 keV), below the limits of standard ion implantation technology. A proposed solution involves implantation of B₁₀H_x⁺ ions in which boron atoms carry less than 10% of the beam energy.

This thesis is a part of the feasibility study of this new technology. An experimental ion implantation system was designed and built at Ion Beam and Thin Film Lab, NJIT. The system was tested and the mass analyzing magnet was calibrated using argon ions. Decaborane ions, …

Selective Area Deposited Blue Gan-Ingan Multiple-Quantum Well Light Emitting Diodes Over Silicon Substrates, J. W. Yang, A. Lunev, Grigory Simin, A. Chitnis, M. Shatalov, M. Asif Khan, Joseph E. Van Nostrand, R. Gaska

Faculty Publications

We report on fabrication and characterization of blue GaN–InGaN multi-quantum well (MQW)light-emitting diodes(LEDs) over (111) silicon substrates. Device epilayers were fabricated using unique combination of molecular beam epitaxy and low-pressure metalorganic chemical vapor depositiongrowth procedure in selective areas defined by openings in a SiO₂mask over the substrates. This selective area deposition procedure in principle can produce multicolor devices using a very simple fabrication procedure. The LEDs had a peak emission wavelength of 465 nm with a full width at half maximum of 40 nm. We also present the spectral emission data with the diodes operating up to 250 …

Electroluminescent Display Device Including Active Polymer Layer, Aemilianus G. J. Staring, David Braun, Karel E. Kuijk

Electrical Engineering

Control device for an electroluminescent display device, comprising an active layer of a semiconducting polymer of, for example pixels arranged in the form of a matrix, reducing flicker and crosstalk. The control device may be based on voltage control at which voltages across the pixels are at least 1.6 V, but is preferably based on current control, at which the duration of the data pulses determines the grey level.

Characteristics Of Free-Standing Hydride-Vapor-Phase-Epitaxy-Grown Gan With Very Low Defect Concentration, P. Visconti, K. M. Jones, Michael A. Reshchikov, F. Yun, R. Cingolani, Hadis Morkoç, S. S. Park, K. Y. Lee

Electrical and Computer Engineering Publications

A free-standing 300-μm-thick GaN template grown by hydride vapor phase epitaxy has been characterized for its structural and optical properties using x-ray diffraction, defect delineation etch followed by imaging with atomic force microscopy, and variable temperature photoluminescence. The Ga face and the N face of the c-plane GaN exhibited a wide variation in terms of the defect density. The defect concentrations on Ga and N faces were about 5×105 cm−2 for the former and about 1×107 cm−2 for the latter. The full width at half maximum of the symmetric (0002) x-ray diffraction peak was 69 and 160 arc sec …

Bias-Assisted Photoelectrochemical Etching Of P-Gan At 300 K, J. E. Borton, C. Cai, M. I. Nathan, P. Chow, J. M. Van Hove, A. Wowchak, Hadis Morkoç

Electrical and Computer Engineering Publications

Photoelectrochemical (PEC)etching of p-type GaN has been realized in room temperature, 0.1 M KOH solutions. PECetching of GaN was achieved by applying a positive bias to the surface of the p-GaN layer through a deposited titanium mask. The applied bias reduces the field at the semiconductor surface, which induced the dissolution of the GaN. The effect of bias on etch rate and morphology was examined. It was found that insulating the Ti mask from the KOH solution with Si3N4 significantly increases the etch rate. The rms roughness of the etched region decreased as the bias voltage increased. Etch rates …

Dislocation Density In Gan Determined By Photoelectrochemical And Hot-Wet Etching, P. Visconti, K. M. Jones, Michael A. Reshchikov, R. Cingolani, Hadis Morkoç, R. J. Molnar

Electrical and Computer Engineering Publications

Defects in GaN layers grown by hydride vapor-phase epitaxy have been investigated by photoelectrochemical (PEC)etching, and by wet etching in hot H3PO4acid and molten potassium hydroxide (KOH). Threading vertical wires (i.e., whiskers) and hexagonal-shaped etch pits are formed on the etched sample surfaces by PEC and wet etching, respectively. Using atomic-force microscopy, we find the density of “whisker-like” features to be 2×109 cm−2, the same value found for the etch-pit density on samples etched with both H3PO4 and molten KOH. This value is comparable to the dislocation density obtained in similar samples with tunnelingelectron microscopy, and is also consistent with …

Observation Of Electronic Raman Scattering From Mg-Doped Wurtzite Gan, K. T. Tsen, C. Koch, Y. Chen, Hadis Morkoç, J. Li, J. Y. Lin, H. X. Jiang

Electrical and Computer Engineering Publications

Electronic Raman scattering experiments have been carried out on both molecular beam epitaxy and metal-organic chemical vapor deposition-grown Mg-doped wurtzite GaN samples. Aside from the expected Raman lines, a broad structure (full width at half maximum≅15 cm−1)observed at around 841 cm−1 is attributed to the electronic Raman scattering from neutral Mg impurities in Mg-doped GaN. Our experimental results demonstrate that the energy between the ground and first excited states of Mg impurities in wurtzite GaN is about one-half of its binding energy.

Well-Width Dependence Of The Ground Level Emission Of Gan/Algan Quantum Wells, A. Bonfiglio, M. Lomascolo, G. Traetta, R. Cingolani, A. Di Carlo, F. Della Sala, P. Lugli, A. Botchkarev, H. Morkoç

Electrical and Computer Engineering Publications

We have performed a systematic investigation of GaN/AlGaN quantum wells grown on different buffer layers (either GaN or AlGaN) in order to clarify the role of strain, structural parameters, and built-in field in determining the well-width dependence of the ground level emission energy. We find that identical quantum wells grown on different buffer layers exhibit strong variation of the ground level energy but similar well-width dependence. The data are quantitatively explained by an analytic model based on the envelope function formalism which accounts for screening and built-in field, and by a full self-consistent tight binding model.

Characterization Of Poly-Si Thin Films Deposited By Magnetron Sputtering Onto Ni Prelayers, Elena A. Guliants, Wayne A. Anderson

Electrical and Computer Engineering Faculty Publications

A method of producing a polycrystalline silicon thin film on a foreign substrate without subsequent annealing has been developed. Thermally evaporated 5–100 nm thick Nifilms served as prelayers for magnetron sputtered Si thin films. A continuous film was obtained as a result of metal induced growth of polysilicon during low temperature (below 600 °C) deposition. The film uniformity is promising for large area device applications. The influence of the Ni prelayer thickness on the grain size of thus obtained films was investigated. Atomic force microscopy and cross-sectional scanning electron microscopy studies revealed features in the 150–600 nm size range while …

Optimal Distributed Binary Hypothesis Testing With Independent Identical Sensors, Q. Zhang, P. K. Varshney, R. D. Wesel

Electrical Engineering and Computer Science - All Scholarship

We consider the problem of distributed binary hypothesis testing with independent identical sensors. It is well known that for this problem the optimal sensor rules are a likelihood ratio threshold tests and the optimal fusion rule is a K-out-of-N rule [1]. Under the Bayesian criterion, we show that for a fixed K-out-of-N fusion rule, the probability of error is a quasiconvex function of the likelihood ratio threshold used in the sensor decision rule. Therefore, the probability of error has a single minimum and a unique optimal threshold achieves this minimum. We obtain a sufficient and necessary condition on the optimal …

On The Error Performance Of 8-Vsb Tcm Decoder For Atsc Terrestrial Broadcasting Of Digital Television, Dojun Rhee, Robert H. Morelos-Zaragoza

Faculty Publications

The error performance of various 8-VSB TCM decoders for reception of terrestrial digital television is analyzed. In previous work, 8-state TCM decoders were proposed and implemented for terrestrial broadcasting of digital television. In this paper, the performance of a 16-state TCM decoder is analyzed and simulated. It is shown that not only a 16-state TCM decoder outperforms one with 8-states, but it also has much smaller error coefficients.

Small Planar Monopole Covers Multiband Brans, Max Ammann, L. E. Doyle

Conference papers

The use of a single antenna which can cover a wide range of frequencies is a desirable feature for future wireless communications systems. The emerging self-organising and ad-hoc networks require more than an octave of bandwidth to facilitate multiband operation. A shorted planar monopole antenna is optimised for future wireless networking bands by suitable choice of planar dimension and feedgap separation. The antenna offers a return-loss greater than 10 dB from 1.60 GHz to 5.90 GHz. The radiation pattern is shown to be quasi-omnidirectional within the 10 dB return-loss bandwidth. Antenna properties are compared with the simple planar monopole.

A Review Of Battery Exchange Technology For Refueling Of Electric Vehicles, C. Arthur Maccarley

Electrical Engineering

The limited energy storage and long recharge time and of electric vehicle batteries have motivated several alternatives to in-vehicle slow charging. Solutions generally fall into three categories: (1) fast charging, in which batteries are charged in-vehicle at an accelerated rate, (2) battery material reloading or refueling, in which the energy-carrying elements of the battery are physically replaced or replenished, and (3) battery interchange, involving the complete exchange of the battery pack, usually with the aid of some semi-automated mechanism. Among these options, the last, battery interchange, has tended to receive the least industry attention, but has been an expansive topic …

Ambiguity Function Of An Ultrawideband Random Noise Radar, Muhammad Dawood, Ram M. Narayanan

Department of Electrical and Computer Engineering: Faculty Publications

The University of Nebraska has developed an ultra-wideband (UWB) random noise radar system which transmits an ultra-wideband random noise (Gaussian) waveform with a uniform power spectral density (PSD) in the 1-2 GHz frequency range. The ability of the system to characterize the Doppler shift of moving targets exhibiting varying linear and rotational velocities was clearly demonstrated [l, 2]. In this paper, we look at the range and range rate resolution issues by analyzing the Woodward’s ambiguity function [3]. In general, the radar signal ambiguity function is defined as the normalized response of a filter matched to a return signal with …

Class Project On Airborne Radar System Design And Development For Remote Sensing Applications, Ram M. Narayanan, K. Jon Ranson

Department of Electrical and Computer Engineering: Faculty Publications

A unique experiment on remote sensing education has recently been undertaken involving an educational institution (University of Nebraska-Lincoln) and a government agency involved in remote sensing (NASA Goddard Space Flight Center). The centerpiece of this experiment is the assignment of an airborne radar system design project to students enrolled in a senior undergraduate and graduate level class on Radar Systems. The class was split into two competing teams. A fictitious request for proposal (RFP) was issued by NASA GSFC, and the teams responded to the RFF’ by proposing and defending competing designs. The teams also prepared final design reports, and …

A Comparative Study Of Uwb Fopen Radar Imaging Using Step-Frequency And Random Noise Waveforms, Xiaojian Xu, Ram M. Narayanan

Department of Electrical and Computer Engineering: Faculty Publications

The detection and identification of targets that are obscured by foliage have been topics of great interest. Several experimental developments of such ultrawideband (UWB) radars have been published. By operating in the VHF and UHF frequency bands and using either LFM or step-frequency waveforms, these radars have demonstrated promising images of terrain and man-made objects obscured by dense foliage [l]. The University of Nebraska has developed a new technique that permits coherent processing of backscatter data acquired by a radar that transmits UWB random noise signals. This technique has been used in various applications, such as ground penetration detection of …

Bottom-Up Design Of Artificial Neural Network For Single-Lead Electrocardiogram Beat And Rhythm Classification, Srikanth Thiagarajan

Doctoral Dissertations

Performance improvement in computerized Electrocardiogram (ECG) classification is vital to improve reliability in this life-saving technology. The non-linearly overlapping nature of the ECG classification task prevents the statistical and the syntactic procedures from reaching the maximum performance. A new approach, a neural network-based classification scheme, has been implemented in clinical ECG problems with much success. The focus, however, has been on narrow clinical problem domains and the implementations lacked engineering precision. An optimal utilization of frequency information was missing. This dissertation attempts to improve the accuracy of neural network-based single-lead (lead-II) ECG beat and rhythm classification. A bottom-up approach defined …

Two Separate Continually Online Trained Neurocontrollers For Excitation And Turbine Control Of A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the design of two separate continually online trained (GOT) artificial neural network (ANN) controllers for excitation and turbine control of a turbogenerator connected to the infinite bus through a transmission line. These neurocontrollers augment/replace the conventional automatic voltage regulator and the turbine governor of a generator. A third COT ANN is used to identify the complex nonlinear dynamics of the power system. Results are presented to show that the two COT ANN controllers can control turbogenerators under steady state as well as transient conditions and thus allow turbogenerators to operate more closely to their steady state stability …

Structural Characterization Of Rapid Thermal Oxidized Si1−X−YGeXCY Alloy Films Grown By Rapid Thermal Chemical Vapor Deposition, W. K. Choi, J. H. Chen, L. K. Bera, W. Feng, K. L. Pey, J. Mi, Cary Y. Yang, A. Ramam, S. J. Chua, J. S. Pan, A. T.S. Wee, R Liu

Electrical and Computer Engineering

The structural properties of as-grown and rapid thermal oxidized Si_1−x−yGe_xC_y epitaxial layers have been examined using a combination of infrared, x-ray photoelectron, x-ray diffraction, secondary ion mass spectroscopy, and Raman spectroscopy techniques. Carbon incorporation into the Si_1−x−yGe_xC_y system can lead to compressive or tensile strain in the film. The structural properties of the oxidized Si_1−x−yGe_xC_y film depend on the type of strain (i.e., carbon concentration) of the as-prepared film. For compressive or fully compensated films, the oxidation process drastically reduces the carbon content so that …

Control Of Statcom With Energy Storage Device, Chen Shen, Zhiping Yang, Stan Atcitty, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the control method of a STATCOM with an energy storage device is discussed. To determine the switching level control, UPWM (unique pulse width modulation) and SPWM (sinusoidal pulse width modulation) methods are compared. A linearized model of a STATCOM with a battery is set up to derive monitoring level control strategies. All the control methods are verified by the PSCAD/EMTDC software package.

Integrated Floorplanning And Buffer Insertion For Bus-Based Microprocessor Designs, Faran Rafiq

Dissertations and Theses

In this thesis, we propose a novel algorithm for the interconnect driven floorplanning problem that integrates bus planning with floorplanning. This integrated floorplanner is intended for bus-based designs in which the layout is considered to be a set of blocks connected through buses. Each bus consists of a large number of wires. Our floorplanner allocates the exact location and shape of the interconnect (both above and between the circuit blocks) and ensures routability as well as optimizes the timing goals. Our experiments with benchmarks clearly show the superiority of integrated floorplanning approach over the classical floorplan-analyze-and-then-refloorplan approach. Our initial results …