Computer Engineering Commons^™

Time–Frequency Cepstral Features And Heteroscedastic Linear Discriminant Analysis For Language Recognition, Wei-Qiang Zhang, Liang He, Yan Deng, Jia Liu, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

The shifted delta cepstrum (SDC) is a widely used feature extraction for language recognition (LRE). With a high context width due to incorporation of multiple frames, SDC outperforms traditional delta and acceleration feature vectors. However, it also introduces correlation into the concatenated feature vector, which increases redundancy and may degrade the performance of backend classifiers. In this paper, we first propose a time-frequency cepstral (TFC) feature vector, which is obtained by performing a temporal discrete cosine transform (DCT) on the cepstrum matrix and selecting the transformed elements in a zigzag scan order. Beyond this, we increase discriminability through a heteroscedastic …

Effects Of Su-8 Cross-Linking On Flip-Chip Bond Strength When Assembling And Packaging Mems, Nathan E. Glavitz, Lavern A. Starman, Ronald A. Coutu Jr., Richard L. Johnson

Electrical and Computer Engineering Faculty Research and Publications

New methods to assemble, integrate, and package micro devices are always needed in attempts to simplify and expedite fabrication methods to maximize throughput. Our paper focuses on assessing SU-8 as a viable material for packaging and flip chip bonding processes for MEMS and micro devices. In this paper, we vary the level of cross- linking through post exposure bake (PEB) times and assess rectangular ring test structures bonding strength following flip chip bonding through applied tensile loads. In addition, we performed initial assessments on the etching resiliency of varied cross-linking of SU-8. From initial results, the bonding strength is maximized …

6.4 Ghz Acoustic Sensor For In-Situ Monitoring Of Afm Tip Wear, T.J. Cheng, Jun Hyun Han, Michael Ziwisky, Chung-Hoon Lee, S.A. Bhave

Electrical and Computer Engineering Faculty Research and Publications

This paper demonstrates an acoustic sensor that can resolve atomic force microscopy (AFM) tip blunting with a frequency sensitivity of 0.007%. The AFM tip is fabricated on a thin film piezoelectric aluminum nitride (AlN) membrane that is excited as a film bulk acoustic resonator (FBAR). We demonstrate that cutting 0.98 μm off of the tip apex results in a resonance frequency change of 0.4MHz at 6.387GHz. This work demonstrates the potential for in-situ monitoring of AFM tip wear.

Data Compressive Paradigm For Multispectral Sensing Using Tunable Dwell Mid-Infrared Detectors, Woo-Yong Jang, Majeed M. Hayat, Sebastian E. Godoy, Steven C. Bender, Payman Zarkesh-Ha, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

While quantum dots-in-a-well (DWELL) infrared photodetectors have the feature that their spectral responses can be shifted continuously by varying the applied bias, the width of the spectral response at any applied bias is not sufficiently narrow for use in multispectral sensing without the aid of spectral filters. To achieve higher spectral resolutions without using physical spectral filters, algorithms have been developed for post-processing the DWELL’s bias-dependent photocurrents resulting from probing an object of interest repeatedly over a wide range of applied biases. At the heart of these algorithms is the ability to approximate an arbitrary spectral filter, which we desire …

Application Of Spatial Bandwidth Concepts To Mas Pole Location For Dielectric Cylinders, James Richie

Electrical and Computer Engineering Faculty Research and Publications

The concept of effective spatial bandwidth (EBW) is extended from the case of an MAS solution for perfectly conducting (PEC) cylinders to dielectric cylinders. It is shown that the ideas and results for the conducting cylinder apply in a straightforward manner to the dielectric case. For the dielectric case, there are two auxiliary surfaces. Because the EBW calculations are independent of the scatterer material, the auxiliary surface for the scattered field will follow the same guidelines for both the PEC and dielectric cases. The guidelines for the second auxiliary surface are described and verified here. Guidelines for both a plane …

Nano-Electromechanical Zero-Dimensional Freestanding Nanogap Actuator, Jun Hyun Han, Norimasa Yoshimizu, T.J. Cheng, Michael Ziwisky, S.A. Bhave, A. Lal, Chung-Hoon Lee

Electrical and Computer Engineering Faculty Research and Publications

Micromachined free standing nanogap with metal electrodes is presented. The gap size is as small as 17 nm, and can be reduced further with electrostatic or piezoelectric actuation. The nanoscale gap is fabricated by industrial standard optical lithography and anisotropic wet chemical Si etching. Electron transport between the metal electrodes with optical stimulus enhancing photon-electron coupling (plasmon) is presented.

Integrated Freestanding Single-Crystal Silicon Nanowires: Conductivity And Surface Treatment, Chung-Hoon Lee, Clark Ritz, Minghuang Huang, Michael Ziwisky, Robert Blise, Max Lagally

Electrical and Computer Engineering Faculty Research and Publications

Integrated freestanding single-crystal silicon nanowires with typical dimension of 100 nm × 100 nm × 5 µm are fabricated by conventional 1:1 optical lithography and wet chemical silicon etching. The fabrication procedure can lead to wafer-scale integration of silicon nanowires in arrays. The measured electrical transport characteristics of the silicon nanowires covered with/without SiO₂ support a model of Fermi level pinning near the conduction band. The I–V curves of the nanowires reveal a current carrier polarity reversal depending on Si–SiO₂ and Si–H bonds on the nanowire surfaces

Midwave Infrared Quantum Dot Avalanche Photodiode, David A. Ramirez, Jiayi Shao, Majeed M. Hayat, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

We report the first demonstration of a GaAs based avalanche photodiode (APD) operating in the midwave infrared region . In the device, called the quantum dot avalanche photodiode, an intersubband quantum dots-in-a-well detector is coupled with an APD through a tunnel barrier. Using this approach, we have increased the photocurrent and reached a conversion efficiency of 12%, which is one of the highest reported conversion efficiencies for any quantum dot detector.

A Parallel Histogram-Based Particle Filter For Object Tracking On Simd-Based Smart Cameras, Henry Medeiros, Germán Holguín, Paul J. Shin, Johnny Park

Electrical and Computer Engineering Faculty Research and Publications

We present a parallel implementation of a histogram-based particle filter for object tracking on smart cameras based on SIMD processors. We specifically focus on parallel computation of the particle weights and parallel construction of the feature histograms since these are the major bottlenecks in standard implementations of histogram-based particle filters. The proposed algorithm can be applied with any histogram-based feature sets—we show in detail how the parallel particle filter can employ simple color histograms as well as more complex histograms of oriented gradients (HOG). The algorithm was successfully implemented on an SIMD processor and performs robust object tracking at up …

Mas Pole Location And Effective Spatial Bandwidth Of The Scattered Field, James Richie

Electrical and Computer Engineering Faculty Research and Publications

The concept of effective spatial bandwidth (EBW) is introduced for periodic domains. The EBW is applied to the incident and scattered fields along the boundary of an infinite circular cylinder. The scattered field is formulated using the method of auxiliary sources (MAS). In MAS, monopoles on an auxiliary surface (AS) are used to model the scattered field. It is shown that the EBW of the incident field can provide some insight regarding the placement of poles for the MAS scattered field model. Example simulations are provided to demonstrate the usefulness of EBW with respect to monopole placement rules in MAS.

Maximizing Service Reliability In Distributed Computing Systems With Random Node Failures: Theory And Implementation, Jorge E. Pezoa, Sagar Dhakal, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

In distributed computing systems (DCSs) where server nodes can fail permanently with nonzero probability, the system performance can be assessed by means of the service reliability, defined as the probability of serving all the tasks queued in the DCS before all the nodes fail. This paper presents a rigorous probabilistic framework to analytically characterize the service reliability of a DCS in the presence of communication uncertainties and stochastic topological changes due to node deletions. The framework considers a system composed of heterogeneous nodes with stochastic service and failure times and a communication network imposing random tangible delays. The framework also …

Cluster-Based Distributed Face Tracking In Camera Networks, Josiah Yoder, Henry Medeiros, Johnny Park, Avinash Kak

Electrical and Computer Engineering Faculty Research and Publications

In this paper, we present a distributed multicamera face tracking system suitable for large wired camera networks. Unlike previous multicamera face tracking systems, our system does not require a central server to coordinate the entire tracking effort. Instead, an efficient camera clustering protocol is used to dynamically form groups of cameras for in-network tracking of individual faces. The clustering protocol includes cluster propagation mechanisms that allow the computational load of face tracking to be transferred to different cameras as the target objects move. Furthermore, the dynamic election of cluster leaders provides robustness against system failures. Our experimental results show that …

Online Drift Compensation For Chemical Sensors Using Estimation Theory, Thomas H. Wenzel, Arnold Kweku Mensah-Brown, Fabien Josse, Edwin E. Yaz

Electrical and Computer Engineering Faculty Research and Publications

Sensor drift from slowly changing environmental conditions and other instabilities can greatly degrade a chemical sensor's performance, resulting in poor identification and analyte quantification. In the present work, estimation theory (i.e., various forms of the Kalman filter) is used for online compensation of baseline drift in the response of chemical sensors. Two different cases, which depend on the knowledge of the characteristics of the sensor system, are studied. First, an unknown input is considered, which represents the practical case of analyte detection and quantification. Then, the more general case, in which the sensor parameters and the input are both unknown, …

Design Of A Transtibial Prosthesis Utilizing Active And Passive Components In Conjunction With A Four-Bar Mechanism, Bryan Bergelin

Master's Theses (2009 -)

This thesis outlines the design and testing of a powered ankle prosthesis which utilizes a four-bar mechanism in conjunction with a spiral torsion spring and a servo motor that mimics non-amputee (normal) ankle moments during the stance phase of gait. Previous research has shown that this novel approach is feasible, but the proof-of-concept prototype was not designed to be able to be worn by an amputee due to size, strength and mobility limitations. The goal of this research was to redesign the transtibial prosthesis to fit the requirements of the targeted amputee population. A preliminary virtual prosthesis was designed using …

Knowledge Discovery And Analysis In Manufacturing, Mark Polczynski, Andzrej Kochanski

Electrical and Computer Engineering Faculty Research and Publications

The quality and reliability requirements for next-generation manufacturing are reviewed, and current approaches are cited. The potential for augmenting current quality/reliability technology is described, and characteristics of potential future directions are postulated. Methods based on knowledge discovery and analysis in manufacturing (KDAM) are reviewed, and related successful applications in business and social fields are discussed. Typical KDAM applications are noted, along with general functions and specific KDAM-related technologies. A systematic knowledge discovery process model is reviewed, and examples of current work are given, including description of successful applications of KDAM to creation of rules for optimizing gas porosity in sand …

Bi-Planar Postural Stability Model: Fitting Parameters To Patient Data Automatically, Andrew Michael Sovol

Master's Theses (2009 -)

Studies of children with cerebral palsy (CP) have shown that maintaining control of posture in quiet standing is often difficult. Physical therapy and assistive devices, both with or without surgery, may be employed in an effort to improve postural stability. Assessing the effectiveness of such interventions is important for healthcare providers and their patients. A previously created bi-planar model of posture control has been further developed as a method of assessment. This MATLAB and Simulink model has successfully replicated experimental results for typical adults and children, as well as children with CP across three different test conditions: eyes open, eyes …

A Voip Implementation On An Embedded Platform, Zachary D. Lund

Master's Theses (2009 -)

This thesis presents a method of building an open VoIP telephone using off-the-shelf hardware. VoIP has become an important area of study in computer science and engineering, but many of the pieces are expensive and proprietary. We discuss the process of building an open IP telephone, the design decisions and difficulties, a performance evaluation of the different pieces of the system, and methods and suggestions for improving the overall system.

The IP telephone is built on the Freescale 68HC12 microcontroller because of its analog and digital capabilities and the Linksys WRT54GL router for its embedded simplicity and network capabilities. The …

Editorial Special Issue On Enhancement Algorithms, Methodologies And Technology For Spectral Sensing, James O. Jensen, Robert J. Trew, Dwight L. Woolard, Neelam Gupta, Jean-Marc Theriault, Majeed M. Hayat, Yanqiu Li, Patti Gillespie

Electrical and Computer Engineering Faculty Research and Publications

The paper is an editorial issue on enhancement algorithms, methodologies and technology for spectral sensing and serves as a valuable and useful reference for researchers and technologists interested in the evolving state-of-the-art and/or the emerging science and technology base associated with spectral-based sensing and monitoring problem. This issue is particularly relevant to those seeking new and improved solutions for detecting chemical, biological, radiological and explosive threats on the land, sea, and in the air.

Shift Estimation Algorithm For Dynamic Sensors With Frame-To-Frame Variation In Their Spectral Response, Todd M. Giles, Majeed M. Hayat, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

This study is motivated by the emergence of a new class of tunable infrared spectral-imaging sensors that offer the ability to dynamically vary the sensor's intrinsic spectral response from frame to frame in an electronically controlled fashion. A manifestation of this is when a sequence of dissimilar spectral responses is periodically realized, whereby in every period of acquired imagery, each frame is associated with a distinct spectral band. Traditional scene-based global shift estimation algorithms are not applicable to such spectrally heterogeneous video sequences, as a pixel value may change from frame to frame as a result of both global motion …

Effects Of Hydrogen Pretreatment On Physical-Vapor-Deposited Nickel Catalyst For Multi-Walled Carbon Nanotube Growth, Benjamin L. Crossley, Mauricio Kossler, Ronald A. Coutu Jr., Lavern A. Starman, Peter J. Collins

Electrical and Computer Engineering Faculty Research and Publications

Physical vapor deposited nickel catalyst layers of 10, 50, 100, 200, 350, and 500 angstroms were granulated using hydrogen plasma for varying times to determine an effective carbon nanotube (CNT) growth process using microwave plasma enhanced CVD (MPECVD). Nickel was deposited via sputtering or evaporation. The catalyst granule size, density, and resulting CNTs were analyzed. Sputtered nickel of 50 angstroms with 5 minutes of hydrogen plasma pretreatment resulted in the most effective CNT growth.

Acoustic Censusing Using Automatic Vocalization Classification And Identity Recognition, Kuntoro Adi, Michael T. Johnson, Tomasz S. Osiejuk

Electrical and Computer Engineering Faculty Research and Publications

This paper presents an advanced method to acoustically assess animal abundance. The framework combines supervised classification (song-type and individual identity recognition), unsupervised classification (individual identity clustering), and the mark-recapture model of abundance estimation. The underlying algorithm is based on clustering using hidden Markovmodels (HMMs) and Gaussian mixture models (GMMs) similar to methods used in the speech recognition community for tasks such as speaker identification and clustering. Initial experiments using a Norwegian ortolan bunting (Emberiza hortulana) data set show the feasibility and effectiveness of the approach. Individually distinct acoustic features have been observed in a wide range of animal …

Information Theoretic Approach For Assessing Image Fidelity In Photon-Counting Arrays, Srikanth R. Narravula, Majeed M. Hayat, Bahram Javidi

Electrical and Computer Engineering Faculty Research and Publications

The method of photon-counting integral imaging has been introduced recently for three-dimensional object sensing, visualization, recognition and classification of scenes under photon-starved conditions. This paper presents an information-theoretic model for the photon-counting imaging (PCI) method, thereby providing a rigorous foundation for the merits of PCI in terms of image fidelity. This, in turn, can facilitate our understanding of the demonstrated success of photon-counting integral imaging in compressive imaging and classification. The mutual information between the source and photon-counted images is derived in a Markov random field setting and normalized by the source-image’s entropy, yielding a fidelity metric that is between …

Measurement And Modeling Of Infrared Nonlinear Absorption Coefficients And Laser-Induced Damage Thresholds In Ge And Gasb, T. J. Wagner, M. A. Bohn, Ronald A. Coutu Jr., L. P. Gonzalez, J. M. Murray, K. L. Schepler, S. Guha

Electrical and Computer Engineering Faculty Research and Publications

Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 μm for the first time, to our knowledge. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 μm and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al₂O₃ anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for picosecond or nanosecond …

A Framework For Bioacoustic Vocalization Analysis Using Hidden Markov Models, Yao Ren, Michael T. Johnson, Patrick J. Clemins, Michael Darre, Sharon Stuart Glaeser, Tomasz S. Osiejuk, Ebenezer Out-Nyarko

Electrical and Computer Engineering Faculty Research and Publications

Using Hidden Markov Models (HMMs) as a recognition framework for automatic classification of animal vocalizations has a number of benefits, including the ability to handle duration variability through nonlinear time alignment, the ability to incorporate complex language or recognition constraints, and easy extendibility to continuous recognition and detection domains. In this work, we apply HMMs to several different species and bioacoustic tasks using generalized spectral features that can be easily adjusted across species and HMM network topologies suited to each task. This experimental work includes a simple call type classification task using one HMM per vocalization for repertoire analysis of …

Demonstration Of A Bias Tunable Quantum Dots-In-A-Well Focal Plane Array, Jonathan Andrews, Woo-Yong Jang, Jorge E. Pezoa, Yagya D. Sharma, Sang Jun Lee, Sam Kyu Noh, Majeed M. Hayat, Sergio Restaino, Scott W. Teare, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

Infrared detectors based on quantum wells and quantum dots have attracted a lot of attention in the past few years. Our previous research has reported on the development of the first generation of quantum dots-in-a-well (DWELL) focal plane arrays, which are based on InAs quantum dots embedded in an InGaAs well having GaAs barriers. This focal plane array has successfully generated a two-color imagery in the mid-wave infrared (i.e. 3–5 μm) and the long-wave infrared (i.e. 8–12 μm) at a fixed bias voltage. Recently, the DWELL device has been further modified by embedding InAs quantum dots in InGaAs …

Analysis And Diagnostics Of Adjacent And Nonadjacent Broken-Rotor-Bar Faults In Squirrel-Cage Induction Machines, Gennadi Y. Sizov, Ahmed Mohamed Sayed Ahmed, Chia-Chou Yeh, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

In this paper, faults associated with the rotor of an induction machine are considered. More specifically, effects of adjacent and nonadjacent bar breakages on rotor fault diagnostics in squirrel-cage induction machines are studied. It is shown that some nonadjacent bar breakages may result in the masking of the commonly used fault indices and, hence, may lead to a possible misdiagnosis of the machine. A discussion of the possible scenarios of these breakages as well as some conclusions regarding the types of squirrel-cage induction machines (number of poles, number of squirrel-cage bars, etc.) that may be more prone to these nonadjacent …

Bit Error Rates For Ultrafast Apd Based Optical Receivers: Exact And Large Deviation Based Asymptotic Approaches, Peng Sun, Majeed M. Hayat, Abhik K. Das

Electrical and Computer Engineering Faculty Research and Publications

Exact analysis as well as asymptotic analysis, based on large-deviation theory (LDT), are developed to compute the bit-error rate (BER) for ultrafast avalanche-photodiode (APD) based optical receivers assuming on-off keying and direct detection. The effects of intersymbol interference (ISI), resulting from the APD's stochastic avalanche buildup time, as well as the APD's dead space are both included in the analysis. ISI becomes a limiting factor as the transmission rate approaches the detector's bandwidth, in which case the bit duration becomes comparable to APD's avalanche buildup time. Further, the effect of dead space becomes significant in high-speed APDs that employ thin …

Optimization Of Inp Apds For High-Speed Lightwave Systems, Daniel S.G. Ong, Jo Shien Ng, Majeed M. Hayat, John P.R. David

Electrical and Computer Engineering Faculty Research and Publications

Calculations based on a rigorous analytical model are carried out to optimize the width of the indium phosphide avalanche region in high-speed direct-detection avalanche photodiode-based optical receivers. The model includes the effects of intersymbol interference (ISI), tunneling current, avalanche noise, and its correlation with the stochastic avalanche duration, as well as dead space. A minimum receiver sensitivity of -28 dBm is predicted at an optimal width of 0.18 mum and an optimal gain of approximately 13, for a 10 Gb/s communication system, assuming a Johnson noise level of 629 noise electrons per bit. The interplay among the factors controlling the …

Efficient Embedded Speech Recognition For Very Large Vocabulary Mandarin Car-Navigation Systems, Yanmin Qian, Jia Liu, Michael T. Johnson

Electrical and Computer Engineering Faculty Research and Publications

Automatic speech recognition (ASR) for a very large vocabulary of isolated words is a difficult task on a resource-limited embedded device. This paper presents a novel fast decoding algorithm for a Mandarin speech recognition system which can simultaneously process hundreds of thousands of items and maintain high recognition accuracy. The proposed algorithm constructs a semi-tree search network based on Mandarin pronunciation rules, to avoid duplicate syllable matching and save redundant memory. Based on a two-stage fixed-width beam-search baseline system, the algorithm employs a variable beam-width pruning strategy and a frame-synchronous word-level pruning strategy to significantly reduce recognition time. This algorithm …

Demonstration Of Bias-Controlled Algorithmic Tuning Of Quantum Dots In A Well (Dwell) Midir Detectors, Woo-Yong Jang, Majeed M. Hayat, J. Scott Tyo, Ram S. Attaluri, Thomas E. Vandervelde, Yagya D. Sharma, Rajeev Shenoi, Andreas Stintz, Elizabeth R. Cantwell, Steven C. Bender, Sang Jun Lee, Sam Kyu Noh, Sanjay Krishna

Electrical and Computer Engineering Faculty Research and Publications

The quantum-confined Stark effect in intersublevel transitions present in quantum-dots-in-a-well (DWELL) detectors gives rise to a midIR spectral response that is dependent upon the detector's operational bias. The spectral responses resulting from different biases exhibit spectral shifts, albeit with significant spectral overlap. A postprocessing algorithm was developed by Sakoglu that exploited this bias-dependent spectral diversity to predict the continuous and arbitrary tunability of the DWELL detector within certain limits. This paper focuses on the experimental demonstration of the DWELL-based spectral tuning algorithm. It is shown experimentally that it is possible to reconstruct the spectral content of a target electronically without …