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Articles 271 - 300 of 388
Full-Text Articles in Computer Engineering
Stochastically Resilient Observer Design For A Class Of Continuous-Time Nonlinear Systems, Chung Seop Jeong, Edwin E. Yaz, Yvonne I. Yaz
Stochastically Resilient Observer Design For A Class Of Continuous-Time Nonlinear Systems, Chung Seop Jeong, Edwin E. Yaz, Yvonne I. Yaz
Electrical and Computer Engineering Faculty Research and Publications
This work addresses the design of stochastically resilient or non-fragile continuous-time Luenberger observers for systems with incrementally conic nonlinearities. Such designs maintain the convergence and/or performance when the observer gain is erroneously implemented due possibly to computational errors i.e. round off errors in computing the observer gain or changes in the observer parameters during operation. The error in the observer gain is modeled as a random process and a common linear matrix inequality formulation is presented to address the stochastically resilient observer design problem for a variety of performance criteria. Numerical examples are given to illustrate the theoretical results.
Robust And Resilient Finite-Time Control Of A Class Of Discrete-Time Nonlinear Systems, Mohammad N. Elbsat, Edwin E. Yaz
Robust And Resilient Finite-Time Control Of A Class Of Discrete-Time Nonlinear Systems, Mohammad N. Elbsat, Edwin E. Yaz
Electrical and Computer Engineering Faculty Research and Publications
In this paper, we address the finite-time state-feedback stabilization of a class of discrete-time nonlinear systems with conic type nonlinearities, bounded feedback control gain perturbations, and additive disturbances. Sufficient conditions for the existence of a robust and resilient linear state feedback controller for this class of systems are derived. Then, using linear matrix inequality techniques, a solution for the controller gain is obtained. The developed controller is robust for all unknown nonlinearities lying in a hyper-sphere and all admissible disturbances. Moreover, it is resilient against any bounded perturbations that may alter the controller’s gain by at most a prescribed amount. …
Robust And Resilient State Dependent Control Of Discrete-Time Nonlinear Systems With General Performance Criteria, Xin Wang, Edwin E. Yaz, Yvonne I. Yaz
Robust And Resilient State Dependent Control Of Discrete-Time Nonlinear Systems With General Performance Criteria, Xin Wang, Edwin E. Yaz, Yvonne I. Yaz
Electrical and Computer Engineering Faculty Research and Publications
A novel state dependent control approach for discrete-time nonlinear systems with general performance criteria is presented. This controller is robust for unstructured model uncertainties, resilient against bounded feedback control gain perturbations in achieving optimality for general performance criteria to secure quadratic optimality with inherent asymptotic stability property together with quadratic dissipative type of disturbance reduction. For the system model, unstructured uncertainty description is assumed, which incorporates commonly used types of uncertainties, such as norm-bounded and positive real uncertainties as special cases. By solving a state dependent linear matrix inequality at each time step, sufficient condition for the control solution can …
Characterizing Multi-Walled Carbon Nanotube Synthesis For Field Emission Applications, Benjamin L. Crossley, Nathan Glauvitz, Betty T. Quinton, Ronald A. Coutu Jr., Peter J. Collins
Characterizing Multi-Walled Carbon Nanotube Synthesis For Field Emission Applications, Benjamin L. Crossley, Nathan Glauvitz, Betty T. Quinton, Ronald A. Coutu Jr., Peter J. Collins
Electrical and Computer Engineering Faculty Research and Publications
No abstract provided.
Novel Microelectromechanical Systems Image Reversal Fabrication Process Based On Robust Su-8 Masking Layers, Scott A. Ostrow Ii, Ronald A. Coutu Jr.
Novel Microelectromechanical Systems Image Reversal Fabrication Process Based On Robust Su-8 Masking Layers, Scott A. Ostrow Ii, Ronald A. Coutu Jr.
Electrical and Computer Engineering Faculty Research and Publications
This paper discusses a novel fabrication process that uses a combination of negative and positive photoresists with positive tone photomasks, resulting in masking layers suitable for bulk micromachining high-aspect ratio microelectromechanical systems (MEMS) devices. MicroChem's negative photoresist Nano™ SU-8 and Clariant's image reversal photoresist AZ 5214E are utilized, along with a barrier layer, to effectively convert a positive photomask into a negative image. This technique utilizes standard photolithography chemicals, equipment, and processes, and opens the door for creating complementary MEMS structures without added fabrication delay and cost. Furthermore, the SU-8 masking layer is robust enough to withstand aggressive etch chemistries …
Fault-Tolerant Technique For Δ-Connected Ac-Motor Drives, Ahmed Mohamed Sayed Ahmed, Behrooz Mirafzal, Nabeel Demerdash
Fault-Tolerant Technique For Δ-Connected Ac-Motor Drives, Ahmed Mohamed Sayed Ahmed, Behrooz Mirafzal, Nabeel Demerdash
Electrical and Computer Engineering Faculty Research and Publications
A fault-tolerant technique for motor-drive systems is introduced in this paper. The technique is merely presented for ac motors with Δ-connected circuits in their stator windings. In this technique, the faulty phase is isolated by solid-state switches after the occurrence of a failure in one of the stator phases. Then, the fault-tolerant technique manages current-flow in the remaining healthy phases. This technique is to significantly mitigate torque pulsations, which are caused by an open-Δ configuration in the stator windings. The performance of the fault-tolerant technique was experimentally verified using a 5-hp 460-V induction motor-drive system and the results are presented …
Multispectral Classification With Bias-Tunable Quantum Dots-In-A-Well Focal Plane Arrays, Biliana S. Paskaleva, Woo-Yong Jang, Yagya D. Sharma, Sanjay Krishna, Majeed M. Hayat
Multispectral Classification With Bias-Tunable Quantum Dots-In-A-Well Focal Plane Arrays, Biliana S. Paskaleva, Woo-Yong Jang, Yagya D. Sharma, Sanjay Krishna, Majeed M. Hayat
Electrical and Computer Engineering Faculty Research and Publications
Mid-wave and long-wave infrared (IR) quantum-dots-in-a-well (DWELL) focal plane arrays (FPAs) are promising technology for multispectral (MS) imaging and sensing. The DWELL structure design provides the detector with a unique property that allows the spectral response of the detector to be continuously, albeit coarsely, tuned with the applied bias. In this paper, a MS classification capability of the DWELL FPA is demonstrated. The approach is based upon: 1) imaging an object repeatedly using a sequence of bias voltages in the tuning range of the FPA and then 2) applying a classification algorithm to the totality of readouts, over multiple biases, …
Reliability Testing Of Algan/Gan Hemts Under Multiple Stressors, Bradley D. Christiansen, Ronald A. Coutu Jr., Eric R. Heller, Brian S. Poling, Glen D. Via, Ramakrishna Vetury, Jeffrey B. Shealy
Reliability Testing Of Algan/Gan Hemts Under Multiple Stressors, Bradley D. Christiansen, Ronald A. Coutu Jr., Eric R. Heller, Brian S. Poling, Glen D. Via, Ramakrishna Vetury, Jeffrey B. Shealy
Electrical and Computer Engineering Faculty Research and Publications
We performed an experiment on AlGaN/GaN HEMTs with high voltage and high power as stressors. We found that devices tested under high power generally degraded more than those tested under high voltage. In particular, the high-voltage-tested devices did not degrade significantly as suggested by some papers in the literature. The same papers in the literature also suggest that high voltages cause cracks and pits. However, the high-voltage-tested devices in this study do not exhibit cracks or pits in TEM images, while the high-power-tested devices exhibit pits.
Sensitivity Of High-Speed Lightwave System Receivers Using Inalas Avalanche Photodiodes, Daniel S.G. Ong, Majeed M. Hayat, John P.R. David, Jo Shien Ng
Sensitivity Of High-Speed Lightwave System Receivers Using Inalas Avalanche Photodiodes, Daniel S.G. Ong, Majeed M. Hayat, John P.R. David, Jo Shien Ng
Electrical and Computer Engineering Faculty Research and Publications
Calculations based on a rigorous analytical model are carried out to compare the sensitivity of optical receivers that use InP and In0.52Al0.48As avalanche photodiodes (APDs). The model includes the effects of intersymbol interference, tunneling current, avalanche noise and its correlation with the stochastic avalanche duration, dead space, and transimpedance amplifier noise. For a 10-Gb/s system with a bit-error rate of 10-12, the optimum receiver sensitivity predicted for In0.52Al0.48As and InP APDs is -28.6 and -28.1 dBm, respectively, corresponding to a reduction of 11% in optical signal power for receivers using …
Versatile Spectral Imaging With An Algorithm-Based Spectrometer Using Highly Tuneable Quantum Dot Infrared Photodetectors, Peter Vines, Chee Hing Tan, John P.R. David, Ram S. Attaluri, Thomas E. Vanderveldt, Sanjay Krishna, Woo-Yong Jang, Majeed M. Hayat
Versatile Spectral Imaging With An Algorithm-Based Spectrometer Using Highly Tuneable Quantum Dot Infrared Photodetectors, Peter Vines, Chee Hing Tan, John P.R. David, Ram S. Attaluri, Thomas E. Vanderveldt, Sanjay Krishna, Woo-Yong Jang, Majeed M. Hayat
Electrical and Computer Engineering Faculty Research and Publications
We report on the implementation of an algorithm-based spectrometer capable of reconstructing the spectral shape of materials in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) wavelengths using only experimental photocurrent measurements from quantum dot infrared photodetectors (QDIPs). The theory and implementation of the algorithm will be described, followed by an investigation into this algorithmic spectrometer's performance. Compared to the QDIPs utilized in an earlier implementation, the ones used here have highly varying spectral shapes and four spectral peaks across the MWIR and LWIR wavelengths. It has been found that the spectrometer is capable of reconstructing broad spectral features of …
Time–Frequency Cepstral Features And Heteroscedastic Linear Discriminant Analysis For Language Recognition, Wei-Qiang Zhang, Liang He, Yan Deng, Jia Liu, Michael T. Johnson
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
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
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
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
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
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
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
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
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
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
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
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
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, …
Knowledge Discovery And Analysis In Manufacturing, Mark Polczynski, Andzrej Kochanski
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 …
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
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
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
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
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
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
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 …