Computer Engineering Commons^™

Mathematical Models For Natural Gas Forecasting, Steven Vitullo, Ronald H. Brown, George F. Corliss, Brian M. Marx

Electrical and Computer Engineering Faculty Research and Publications

It is vital for natural gas Local Distribution Companies (LDCs) to forecast their customers' natural gas demand accurately. A significant error on a single very cold day can cost the customers of the LDC millions of dollars. This paper looks at the financial implication of forecasting natural gas, the nature of natural gas forecasting, the factors that impact natural gas consumption, and describes a survey of mathematical techniques and practices used to model natural gas demand. Many of the techniques used in this paper currently are implemented in a software GasDay^TM, which is currently used by 24 LDCs …

A Pilot Study Evaluating Use Of A Computer-Assisted Neurorehabilitation Platform For Upper-Extremity Stroke Assessment, Xin Feng, Jack Winters

Electrical and Computer Engineering Faculty Research and Publications

Background

There is a need to develop cost-effective, sensitive stroke assessment instruments. One approach is examining kinematic measures derived from goal-directed tasks, which can potentially be sensitive to the subtle changes in the stroke rehabilitation process. This paper presents the findings from a pilot study that uses a computer-assisted neurorehabilitation platform, interfaced with a conventional force-reflecting joystick, to examine the assessment capability of the system by various types of goal-directed tasks.

Methods

Both stroke subjects with hemiparesis and able-bodied subjects used the force-reflecting joystick to complete a suite of goal-directed tasks under various task settings. Kinematic metrics, developed for specific …

Dependence Of The Performance Of Single Photon Avalanche Diodes On The Multiplication Region Width, David A. Ramirez, Majeed M. Hayat, Mark A. Itzler

Electrical and Computer Engineering Faculty Research and Publications

The dependence of the performance of separate-absorption-multiplication (SAM) single-photon avalanche diodes (SPADs) on the width of the multiplication region is theoretically investigated. The theory is applied to SAM SPADs with InP homojunction multiplication regions and InAlAs-InP heterojunction multiplication regions. In both cases the absorber layer is InGaAs. Two scenarios for the dark counts are considered: (i) low-temperature operation, when the number of dark carriers is dominated by field-assisted mechanisms of band-to-band tunneling and tunneling through defects; and (ii) room-temperature operation, when the number of dark carriers in the multiplication region is dominated by the generation/recombination mechanism. The analysis utilizes a …

A Reconfigurable Motor For Experimental Emulation Of Stator Winding Inter-Turn And Broken Bar Faults In Polyphase Induction Machines (Journal Article), Chia-Chou Yeh, Gennadi Y. Sizov, Ahmed Sayed-Ahmed, Nabeel Demerdash, Richard J. Povinelli, Edwin E. Yaz, Dan M. Ionel

Electrical and Computer Engineering Faculty Research and Publications

The benefits and drawbacks of a 5-hp reconfigurable induction motor, which was designed for experimental emulation of stator winding interturn and broken rotor bar faults, are presented in this paper. It was perceived that this motor had the potential of quick and easy reconfiguration to produce the desired stator and rotor faults in a variety of different fault combinations. Hence, this motor was anticipated to make a useful test bed for evaluation of the efficacy of existing and new motor fault diagnostics techniques and not the study of insulation failure mechanisms. Accordingly, it was anticipated that this reconfigurable motor would …

Minimum Mean-Squared Error Estimation Of Mel-Frequency Cepstral Coefficients Using A Novel Distortion Model, Kevin M. Indrebo, Richard J. Povinelli, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

In this paper, a new method for statistical estimation of Mel-frequency cepstral coefficients (MFCCs) in noisy speech signals is proposed. Previous research has shown that model-based feature domain enhancement of speech signals for use in robust speech recognition can improve recognition accuracy significantly. These methods, which typically work in the log spectral or cepstral domain, must face the high complexity of distortion models caused by the nonlinear interaction of speech and noise in these domains. In this paper, an additive cepstral distortion model (ACDM) is developed, and used with a minimum mean-squared error (MMSE) estimator for recovery of MFCC features …

Canonical Correlation Feature Selection For Sensors With Overlapping Bands: Theory And Application, Biliana S. Paskaleva, Majeed M. Hayat, Zhipeng Wang, J. Scott Tyo, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

The main focus of this paper is a rigorous development and validation of a novel canonical correlation feature- selection (CCFS) algorithm that is particularly well suited for spectral sensors with overlapping and noisy bands. The proposed approach combines a generalized canonical correlation analysis framework and a minimum mean-square-error criterion for the selection of feature subspaces. The latter induces ranking of the best linear combinations of the noisy overlapping bands and, in doing so, guarantees a minimal generalized distance between the centers of classes and their respective reconstructions in the space spanned by sensor bands. To demonstrate the efficacy and the …

Distributed Object Tracking Using A Cluster-Based Kalman Filter In Wireless Camera Networks, Henry Medeiros, Johnny Park, Avinash Kak

Electrical and Computer Engineering Faculty Research and Publications

Local data aggregation is an effective means to save sensor node energy and prolong the lifespan of wireless sensor networks. However, when a sensor network is used to track moving objects, the task of local data aggregation in the network presents a new set of challenges, such as the necessity to estimate, usually in real time, the constantly changing state of the target based on information acquired by the nodes at different time instants. To address these issues, we propose a distributed object tracking system which employs a cluster-based Kalman filter in a network of wireless cameras. When a target …

Resource-Constrained Load Balancing Controller For A Parallel Database, Z. Tang, J. Douglas Birdwell, J. Chiasson, Chaouki T. Abdallah, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

This brief documents experimental results using a deterministic dynamic nonlinear system for load balancing, previously reported by Tang et al. in a cluster of computer nodes used for parallel computations in the presence of time delays and resource constraints. While previous publications by the authors have provided theoretical analysis of this load-balancing strategy using an idealized model, and have documented experiments using a simulated database, experimental results using a complete database for DNA profiles are documented here. Evaluation of the proposed load-balancing strategy using an actual database was critical because of several characteristics of the database that cannot be accurately …

Induction Machine Broken Bar And Stator Short-Circuit Fault Diagnostics Based On Three Phase Stator Current Envelopes, Aderiano M. Da Silva, Richard J. Povinelli, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

A new method for the fault diagnosis of a broken rotor bar and interturn short circuits in induction machines (IMs) is presented. The method is based on the analysis of the three-phase stator current envelopes of IMs using reconstructed phase space transforms. The signatures of each type of fault are created from the three-phase current envelope of each fault. The resulting fault signatures for the new so-called ldquounseen signalsrdquo are classified using Gaussian mixture models and a Bayesian maximum likelihood classifier. The presented method yields a high degree of accuracy in fault identification as evidenced by the given experimental results, …

Overview Of Biocreative Ii Gene Mention Recognition, Larry Smith, Lorraine K. Tanabe, Rie Johnson Nee Ando, Cheng-Ju Kuo, I-Fang Chung, Chun-Nan Hsu, Yu-Shi Lin, Roman Klinger, Christoph M. Friedrich, Kuzman Ganchev, Manabu Torii, Hongfang Liu, Barry Haddow, Craig A. Struble, Richard J. Povinelli, Andreas Vlachos, William A. Baumgartner, Lawrence Hunter, Bob Carpenter, Richard Tzong-Han Tsai, Hong-Jie Dai, Feng Liu, Yifei Chen, Chengjie Sun, Sophia Katrenko, Pieter Adriaans, Christian Blaschke, Rafael Torres, Mariana Neves, Preslav Nakov, Anna Divoli, Manuel Maña-López, Jacinto Mata, W John Wilbur

Electrical and Computer Engineering Faculty Research and Publications

Nineteen teams presented results for the Gene Mention Task at the BioCreative II Workshop. In this task participants designed systems to identify substrings in sentences corresponding to gene name mentions. A variety of different methods were used and the results varied with a highest achieved F₁ score of 0.8721. Here we present brief descriptions of all the methods used and a statistical analysis of the results. We also demonstrate that, by combining the results from all submissions, an F score of 0.9066 is feasible, and furthermore that the best result makes use of the lowest scoring submissions.

Diagnosis Of Inter-Turn Short Circuit For A Polyphase Induction Motor In Closed-Loop Vector-Controlled Drives, Ahmed Sayed-Ahmed, Gennadi Y. Sizov, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

The main objective of this paper is to develop and experimentally verify a new technique to detect an inter-turn short circuit in one phase of a stator winding of an induction motor energized from a vector-controlled drive. This is in order to overcome the fault masking difficulties associated with the concept of depending on the actual magnetic field pendulous oscillation between the conventional voltage and current space vectors with respect to a reference that is unaltered by the compensation action of the drive. This technique is based on the flux pendulous oscillation phenomenon. This flux pendulous oscillation is also described …

A Light-Weight Event-Driven Protocol For Sensor Clustering In Wireless Camera Networks, Henry Medeiros, Johnny Park, Avinash Kak

Electrical and Computer Engineering Faculty Research and Publications

We propose a light-weight event-driven protocol for wireless camera networks to allow for formation and propagation of clusters of cameras for the purpose of collaborative processing during object tracking. Cluster formation is triggered by the detection of objects with specific features. Our protocol allows for simultaneous formation and propagation of multiple clusters. Cameras being directional devices, more than one cluster may track a single object since groups of cameras outside each others communication range may see the same object. Entry into a cluster and cluster membership maintenance require a sensor node to confirm the presence of features of the object …

Robust Minimum Variance Linear State Estimators For Multiple Sensors With Different Failure Rates, Franck O. Hounkpevi, Edwin E. Yaz

Electrical and Computer Engineering Faculty Research and Publications

Linear minimum variance unbiased state estimation is considered for systems with uncertain parameters in their state space models and sensor failures. The existing results are generalized to the case where each sensor may fail at any sample time independently of the others. For robust performance, stochastic parameter perturbations are included in the system matrix. Also, stochastic perturbations are allowed in the estimator gain to guarantee resilient operation. An illustrative example is included to demonstrate performance improvement over the Kalman filter which does not include sensor failures in its measurement model.

Speech Signal Enhancement Through Adaptive Wavelet Thresholding, Michael T. Johnson, Xiaolong Yuan, Yao Ren

Electrical and Computer Engineering Faculty Research and Publications

This paper demonstrates the application of the Bionic Wavelet Transform (BWT), an adaptive wavelet transform derived from a non-linear auditory model of the cochlea, to the task of speech signal enhancement. Results, measured objectively by Signal-to-Noise ratio (SNR) and Segmental SNR (SSNR) and subjectively by Mean Opinion Score (MOS), are given for additive white Gaussian noise as well as four different types of realistic noise environments. Enhancement is accomplished through the use of thresholding on the adapted BWT coefficients, and the results are compared to a variety of speech enhancement techniques, including Ephraim Malah filtering, iterative Wiener filtering, and spectral …

Potential Of A Suite Of Robot/Computer-Assisted Motivating Systems For Personalized, Home-Based, Stroke Rehabilitation, Michelle J. Johnson, Xin Feng, Laura M. Johnson, Jack M. Winters

Electrical and Computer Engineering Faculty Research and Publications

Background

There is a need to improve semi-autonomous stroke therapy in home environments often characterized by low supervision of clinical experts and low extrinsic motivation. Our distributed device approach to this problem consists of an integrated suite of low-cost robotic/computer-assistive technologies driven by a novel universal access software framework called UniTherapy. Our design strategy for personalizing the therapy, providing extrinsic motivation and outcome assessment is presented and evaluated.

Methods

Three studies were conducted to evaluate the potential of the suite. A conventional force-reflecting joystick, a modified joystick therapy platform (TheraJoy), and a steering wheel platform (TheraDrive) were tested separately with …

Inter-Turn Fault Diagnosis In Induction Motors Using The Pendulous Oscillation Phenomenon, Behrooz Mirafzal, Richard J. Povinelli, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

A robust interturn fault diagnostic approach based on the concept of magnetic field pendulous oscillation, which occurs in induction motors under faulty conditions, is introduced in this paper. This approach enables one to distinguish and classify an unbalanced voltage power supply and machine manufacturing/construction imperfections from an interturn fault. The experimental results for the two case studies of a set of 5-hp and 2-hp induction motors verify the validity of the proposed approach. Moreover, it can be concluded from the experimental results that if the circulating current level in the shorted loop increases beyond the phase current level, an interturn …

Synergistic Use Of Compound Properties And Docking Scores In Neural Network Modeling Of Cyp2d6 Binding: Predicting Affinity And Conformational Sampling, Peter S. Bazeley, Sridevi Prithivi, Craig Struble, Richard J. Povinelli, Daniel S. Sem

Electrical and Computer Engineering Faculty Research and Publications

Cytochrome P450 2D6 (CYP2D6) is used to develop an approach for predicting affinity and relevant binding conformation(s) for highly flexible binding sites. The approach combines the use of docking scores and compound properties as attributes in building a neural network (NN) model. It begins by identifying segments of CYP2D6 that are important for binding specificity, based on structural variability among diverse CYP enzymes. A family of distinct, low-energy conformations of CYP2D6 are generated using simulated annealing (SA) and a collection of 82 compounds with known CYP2D6 affinities are docked. Interestingly, docking poses are observed on the backside of the heme …

Soft-Started Induction Motor Modeling And Heating Issues For Different Starting Profiles Using A Flux Linkage Abc Frame Of Reference, M. G. Solveson, Behrooz Mirafzal, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

In order to mitigate the adverse effects of starting torque transients and high inrush currents in induction motors, a popular method is to use electronically controlled soft-starting voltages utilizing series-connected silicon-controlled rectifiers (SCRs). Investigation of semioptimum soft-starting voltage profiles was implemented using a flux linkage ABC frame of reference model of a soft-started three-phase induction motor. A state-space model of the soft-starter thyristor switching sequence for the motor and load was developed and implemented in a time-domain simulation to examine winding heating and shaft stress issues for different starting profiles. Simulation results of line starts and soft starts were compared …

Sub-Banded Reconstructed Phase Spaces For Speech Recognition, Kevin M Indrebo, Richard J. Povinelli, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

A novel method combining filter banks and reconstructed phase spaces is proposed for the modeling and classification of speech. Reconstructed phase spaces, which are based on dynamical systems theory, have advantages over spectral-based analysis methods in that they can capture nonlinear or higher-order statistics. Recent work has shown that the natural measure of a reconstructed phase space can be used for modeling and classification of phonemes. In this work, sub-banding of speech, which has been examined for recognition of noise-corrupted speech, is studied in combination with phase space reconstruction. This sub-banding, which is motivated by empirical psychoacoustical studies, is shown …

Statistical Models Of Reconstructed Phase Spaces For Signal Classification, Richard J. Povinelli, Michael T. Johnson, Andrew C. Lindgren, Felice M. Roberts, Jinjin Ye

Electrical and Computer Engineering Faculty Research and Publications

This paper introduces a novel approach to the analysis and classification of time series signals using statistical models of reconstructed phase spaces. With sufficient dimension, such reconstructed phase spaces are, with probability one, guaranteed to be topologically equivalent to the state dynamics of the generating system, and, therefore, may contain information that is absent in analysis and classification methods rooted in linear assumptions. Parametric and nonparametric distributions are introduced as statistical representations over the multidimensional reconstructed phase space, with classification accomplished through methods such as Bayes maximum likelihood and artificial neural networks (ANNs). The technique is demonstrated on heart arrhythmia …

Microswitches With Sputtered Au, Aupd,Au-On-Aupt, And Auptcu Alloy Electric Contacts, Ronald A. Coutu Jr., J. R. Reid, R. Cortez, R. E. Strawser, P. E. Kladitis

Electrical and Computer Engineering Faculty Research and Publications

This paper is the first to report on a new analytic model for predicting microcontact resistance and the design, fabrication, and testing of microelectromechanical systems (MEMS) metal contact switches with sputtered bimetallic (i.e., gold (Au)-on-Au-platinum (Pt), (Au-on-Au-(6.3at%)Pt)), binary alloy (i.e., Au-palladium (Pd), (Au-(3.7at%)Pd)), and ternary alloy (i.e., Au-Pt-copper (Cu), (Au-(5.0at%)Pt-(0.5at%)Cu)) electric contacts. The microswitches with bimetallic and binary alloy contacts resulted in contact resistance values between 1-2Omega. Preliminary reliability testing indicates a 3times increase in switching lifetime when compared to microswitches with sputtered Au electric contacts. The ternary alloy exhibited approximately a 6times increase in switch lifetime with contact resistance …

An Lmi Approach To Discrete-Time Observer Design With Stochastic Resilience, Edwin E. Yaz, Chung Seop Jeong, Yvonne I. Yaz

Electrical and Computer Engineering Faculty Research and Publications

Much of the recent work on robust control or observer design has focused on preservation of stability of the controlled system or the convergence of the observer in the presence of parameter perturbations in the plant or the measurement model. The present work addresses the important problem of stochastic resilience or non-fragility of a discrete-time Luenberger observer which is the maintenance of convergence and/or performance when the observer is erroneously implemented possibly due to computational errors i.e. round off errors in digital implementation or sensor errors, etc. A common linear matrix inequality framework is presented to address the stochastic resilient …

Fast Thermal Profiling Of Power Semiconductor Devices Using Fourier Techniques, J. J. Nelson, G. Venkataramanan, Ayman M. El-Refaie

Electrical and Computer Engineering Faculty Research and Publications

Accurate prediction of temperature variation of power semiconductor devices in power electronic circuits is important to obtain optimum designs and estimate reliability levels. Temperature estimation of power electronic devices has generally been performed using transient thermal equivalent circuits. In the presence of varying load cycles, it has been typical to resort to a time-domain electrical simulation tool such as P-Spice or SABER to obtain a time series of the temperature profiles. However, for complex and periodic load cycles, time-series simulation is time consuming. In this paper, a fast Fourier analysis-based approach is presented for obtaining temperature profiles for power semiconductors. …

Analysis Of Surface Permanent Magnet Machines With Fractional-Slot Concentrated Windings, Ayman M. El-Refaie, Thomas M. Jahns, Donald W. Novotny

Electrical and Computer Engineering Faculty Research and Publications

This paper presents a closed-form analytical technique for analyzing surface PM machines equipped with fractional-slot concentrated windings. Since this class of winding configuration deviates significantly from conventional sinusoidal distributions, classical steady-state phasor or analytical techniques cannot be used to provide accurate results. The presented analytical model provides a fast and reliable method to analyze and compare candidate machine designs. Stator slotting effects are taken into consideration and a wide range of concentrated winding configurations can be analyzed. This technique is capable of analyzing the machine both below (constant-torque) and above (flux-weakening) base speed. Average torque, cogging torque, and ripple torque …

On Innovative Methods Of Induction Motor Interturn And Broken-Bar Fault Diagnostics, Behrooz Mirafzal, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

A fault indicator, the so-called swing angle, for broken-bar and interturn faults is investigated in this paper. This fault indicator is based on the rotating magnetic-field pendulous-oscillation concept in faulty squirrel-cage induction motors. Using the "swing-angle indicator," it will be demonstrated here that an interturn fault can be detected even in the presence of machine manufacturing imperfections. Meanwhile, a broken-bar fault can be detected under both direct-line and PWM excitations, even under the more difficult condition of partial-load levels. These two conditions of partial load and motor manufacturing imperfections, which are considered as difficult situations for fault detection, are investigated …

Statistical Correlation Of Gain And Buildup Time In Apds And Its Effects On Receiver Performance, Peng Sun, Majeed M. Hayat, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

This paper reports a novel recurrence theory that enables us to calculate the exact joint probability density function (pdf) of the random gain and the random avalanche buildup time in avalanche photodiodes (APDs) including the effect of dead space. Such calculations reveal a strong statistical correlation between the gain and the buildup time for all widths of the multiplication region. To facilitate the calculation of the photocurrent statistics in the presence of this correlation, the impulse-response function of the APD is approximately modeled by a function of time whose prespecified shape is appropriately parameterized by two random variables: the gain …

Characterization Of Metal And Metal Alloy Films As Contact Materials In Mems Switches, Hyukjae Lee, Ronald A. Coutu Jr., Shankar Mall, Kevin D. Leedy

Electrical and Computer Engineering Faculty Research and Publications

This study presents a basic step toward the selection methodology of electric contact materials for microelectromechanical systems (MEMS) metal contact switches. This involves the interrelationship between two important parameters, resistivity and hardness, since they provide the guidelines and assessment of contact resistance, wear, deformation and adhesion characteristics of MEMS switches. For this purpose, thin film alloys of three noble metals, platinum (Pt), rhodium (Rh) and ruthenium (Ru) with gold (Au), were investigated. The interrelationship between resistivity and hardness was established for three levels of alloying of these metals with gold. Thin films of gold (Au), platinum (Pt), ruthenium (Rh) and …

Detection Efficiencies And Generalized Breakdown Probabilities For Nanosecond-Gated Near Infrared Single-Photon Avalanche Photodiodes, David A. Ramirez, Majeed M. Hayat, Gauri Karve, Joe C. Campbell, Sergio N. Torres, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

A rigorous model is developed for determining single-photon quantum efficiency (SPQE) of single-photon avalanche photodiodes (SPADs) with simple or heterojunction multiplication regions. The analysis assumes nanosecond gated-mode operation of the SPADs and that band-to-band tunneling of carriers is the dominant source of dark current in the multiplication region. The model is then utilized to optimize the SPQE as a function of the applied voltage, for a given operating temperature and multiplication-region structure and material. The model can be applied to SPADs with In/sub 0.52/Al/sub 0.48/As or InP multiplication regions as well as In/sub 0.52/Al/sub 0.48/As--InP heterojunction multiplication regions for wavelengths …

Statistical Adaptive Sensing By Detectors With Spectrally Overlapping Bands, Ünal Sakog ̆ Lu, Majeed M. Hayat, J. Scott Tyo, Philip Dowd, Senthil Annamalai, Kalyan T. Posani, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

It has recently been reported that by using a spectral-tuning algorithm, the photocurrents of multiple detectors with spectrally overlapping responsivities can be optimally combined to synthesize, within certain limits, the response of a detector with an arbitrary responsivity. However, it is known that the presence of noise in the photocurrent can degrade the performance of this algorithm significantly, depending on the choice of the responsivity spectrum to be synthesized. We generalize this algorithm to accommodate noise. The results are applied to quantum-dot mid-infrared detectors with bias-dependent spectral responses. Simulation and experiment are used to show the ability of the algorithm …

Computation Of Bit-Error Probabilities For Optical Receivers Using Thin Avalanche Photodiodes, Byonghyok Choi, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

The large-deviation-based asymptotic-analysis and importance-sampling methods for computing bit-error probabilities for avalanche-photodiode (APD) based optical receivers, developed by Letaief and Sadowsky [IEEE Trans. Inform. Theory, vol. 38, pp. 1162-1169, 1992], are extended to include the effect of dead space, which is significant in high-speed APDs with thin multiplication regions. It is shown that the receiver's bit-error probability is reduced as the magnitude of dead space increases relative to the APD's multiplication-region width. The calculated error probabilities and receiver sensitivities are also compared with those obtained from the Chernoff bound.