Electrical and Computer Engineering Commons^™

Energy Efficient Rgbw Pixel Configuration For Light-Emitting Displays, Neveen Shlayan, Rama Venkat, Paolo Ginobbi, Ashok K. Singh

Electrical & Computer Engineering Faculty Research

A study on LED displays has been conducted exploring a more efficient method for color generation than the traditional method. The study is comprehensive and thoroughly performed employing various sets of experiments in order to examine the functionality of the new proposed scheme which includes a literature review, theoretical modeling based on a scientific study, experimental data measurements of a developed prototype, and statistical data based on a survey. This study resulted in very interesting outcomes that may lead to a tremendous change in the existing LED display technology.

Adaptive Distributed Fair Scheduling For Multiple Channels In Wireless Sensor Networks, Maciej Jan Zawodniok, Jagannathan Sarangapani, Steve Eugene Watkins, James W. Fonda

Electrical and Computer Engineering Faculty Research & Creative Works

A novel adaptive and distributed fair scheduling (ADFS) scheme for wireless sensor networks (WSN) in the presence of multiple channels (MC-ADFS) is developed. The proposed MC-ADFS increases available network capacity and focuses on quality-of-service (QoS) issues. when nodes access a shared channel, the proposed MC-ADFS allocates the channel bandwidth proportionally to the packet's weight which indicates the priority of the packet's flow. The packets are dynamically assigned to channels based on the packet weight and current channel utilization. The dynamic assignment of channels is facilitated by use of receiver-based allocation and alternative routes. Moreover, MC-ADFS allows the dynamic allocation of …

Adaptive Multicast On Mobile Ad Hoc Networks Using Tree-Based Meshes With Variable Density Of Redundant Paths, Sangman Moh, Sang Jun Lee, Chansu Yu

Electrical and Computer Engineering Faculty Publications

Multicasting has been extensively studied for mobile ad hoc networks (MANETs) because it is fundamental to many ad hoc network applications requiring close collaboration of multiple nodes in a group. A general approach is to construct an overlay structure such as multicast tree or mesh and to deliver a multicast packet to multiple receivers over the overlay structure. However, it either incurs a lot of overhead (multicast mesh) or performs poorly in terms of delivery ratio (multicast tree). This paper proposes an adaptive multicast scheme, called tree-based mesh with k-hop redundant paths (TBM _k ), …

Particle Swarm Optimization Tuned Flatness-Based Generator Excitation Controller, Ganesh K. Venayagamoorthy, E. C. Anene, U. O. Aliyu

Electrical and Computer Engineering Faculty Research & Creative Works

An optimal transient controller for a synchronous generator in a multi-machine power system is designed using the concept of flatness-based feedback linearization in this paper. The computation of the flat output and corresponding controller for reduced order model of the synchronous generator is presented. The required feedback gains used to close the linearization loop is optimized using particle swarm optimization for maximum damping. Typical results obtained for transient disturbances on a two-area, four-generator power system equipped with the proposed controller on one generator and conventional power system stabilizers on the remaining generators are presented. The effectiveness of the flatness-based controller …

Analysis Of Globule Types In Malignant Melanoma, Jin Xu, Kapil Kumar Gupta, William V. Stoecker, Yamini Krishnamurthy, Harold S. Rabinovitz, Austin Bangert, David A. Calcara, Margaret C. Oliviero, Joseph M. Malters, Rhett J. Drugge, R. Joe Stanley, Randy Hays Moss, Mehmed Emre Celebi

Chemistry Faculty Research & Creative Works

Objective: To identify and analyze subtypes of globules based on size, shape, network connectedness, pigmentation, and distribution to determine which globule types and globule distributions are most frequently associated with a diagnosis of malignant melanoma. Design: Retrospective case series of dermoscopy images with globules. Setting: Private dermatology practices. Participants: Patients in dermatology practices. Intervention: Observation only. Main Outcome Measure: Association of globule types with malignant melanoma. Results: The presence of large globules (odds ratio [OR], 5.25) and globules varying in size (4.72) or shape (5.37) had the highest ORs for malignant melanoma among all globule types and combinations studied. Classical …

Active Disturbance Rejection Control For Mems Gyroscopes, Qing Zheng, Lili Dong, Dae Hui Lee, Zhiqiang Gao

Electrical and Computer Engineering Faculty Publications

A new control method is presented to drive the drive axis of a Micro-Electro-Mechanical Systems (MEMS) gyroscope to resonance and to regulate the output amplitude of the axis to a fixed level. It is based on a unique active disturbance rejection control (ADRC) strategy, which actively estimates and compensates for internal dynamic changes of the drive axis and external disturbances in real time. The stability analysis shows that both the estimation error and the tracking error of the drive axis output are bounded and that the upper bounds of the errors monotonously decrease with the increase of the controller bandwidth. …

Effects Of Sea-Surface Conditions On Passive Fathometry And Bottom Characterization, Steven L. Means, Martin Siderius

Electrical and Computer Engineering Faculty Publications and Presentations

Recently, a method has been developed that exploits the correlation properties of the ocean’s ambient noise to measure water depth (a passive fathometer) and seabed layering [M. Sideriuset al., J. Acoust. Soc. Am.120, 1315–1323 (2006)]. This processing is based on the cross-correlation between the surface noise and the echo return from the seabed. To quantitatively study the dependency between processing and environmental factors such as wind speed, measurements were made using a fixed hydrophone array while simultaneously characterizing the environment. The measurements were made in 2006 in the shallow waters (25m)approximately 75km off the coast of Savannah, GA. …

A Pll-Based Multirate Structure For Time-Varying Power Systems Harmonic/ Interharmonic Estimation, Janison Rodrigues De Carvalho, Carlos A. Duque, Moisés V. Ribeiro, Augusto S. Cerqueira

University Faculty Publications and Creative Works

This paper describes a phase-locked-loop (PLL)-based power systems harmonic estimation algorithm, which uses an analysis filter bank and multirate processing. The filter bank is composed of bandpass filters. The initial center frequency of each filter is purposely chosen to be equal to harmonic frequencies. However, an adaptation strategy makes it possible to track time-varying frequencies as well as interharmonic components. A downsampler device follows the filtering stage, reducing the computational burden, especially because undersampling operations are performed. Finally, the last stage is composed of a PLL estimator which provides estimates for amplitude, phase, and frequency of the input signal. The …

In-Plane All-Photonic Transduction With Differential Splitter Using Double-Step Rib Waveguide For Photonic Microcantilever Arrays, Ryan Anderson, Seunghyun Kim, Gregory P. Nordin, Jong Wook Noh, Weisheng Hu

Faculty Publications

We report a differential splitter consisting of an asymmetric double-step multimode rib waveguide and a Y-branch splitter for in-plane photonic transduction of photonic microcantilever deflection. Arrays of photonic microcantilevers are integrated with differential splitters and an optical waveguide network to demonstrate uniformity and sensitivity of transduction. Measurement results from multiple arrays indicate a sensitivity of 0.32 x 10-3 nm-1 and minimum detectable deflection of 141 pm for a 3.5 Hz measurement bandwidth.

Wireless Data Acquisition For Photovoltaic Power System, Makbul Anwari, Arief Hidayat, M. Imran Hamid, Taufik

Electrical Engineering

This paper presents a wireless system for monitoring the input and output of the array in a photovoltaic generation plant. The system comprises of sensors, data acquisition system, wireless access point and user computer that enable the users to access the array parameter wirelessly. Description and function of set up equipment are presented as well as the application program that supports the system.

Neural Network Demodulation For An Optical Sensor, Steve Eugene Watkins, Donald C. Wunsch, Rohit Dua

Electrical and Computer Engineering Faculty Research & Creative Works

Methods and systems of neural network demodulation for an optical sensor. An optical sensor may be coupled to a structure and be capable of reflecting a reflected optical signal. A wavelength of the reflected optical signal may be spread based on a strain being applied to the structure. A replication device may receive the reflected optical signal from the optical sensor and produce a plurality of optical signals. A filter may be coupled to the replication device to receive an optical signal from the plurality of optical signals and filter the received optical signal. A detector may receive the filtered …

New Metric Describes Edge Noise In Bilevel Images, Elisa H. Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

A new approach enables quantitative and qualitative characterization of varying edge noise even if the additive noise level is constant.

Shaped Mems Contact, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane

AFIT Patents

A MEMS switch fabrication process and apparatus inclusive of a bulbous rounded surface movable contact assembly that is integral with the switch movable element and achieving of long contact wear life with low contact electrical resistance. The disclosed process is compatible with semiconductor integrated circuit fabrication materials and procedures and includes an unusual photoresist reflow step in which the bulbous contact shape is quickly defined in three dimensions from more easily achieved integrated circuit mask and etching-defined precursor shapes. A plurality of differing photoresist materials are used in the process. A large part of the contact and contact spring formation …

Threshold Selection In Gene Co-Expression Networks Using Spectral Graph Theory Techniques, Andy D. Perkins, Michael A. Langston

Faculty Publications and Other Works -- EECS

Abstract

Background

Gene co-expression networks are often constructed by computing some measure of similarity between expression levels of gene transcripts and subsequently applying a high-pass filter to remove all but the most likely biologically-significant relationships. The selection of this expression threshold necessarily has a significant effect on any conclusions derived from the resulting network. Many approaches have been taken to choose an appropriate threshold, among them computing levels of statistical significance, accepting only the top one percent of relationships, and selecting an arbitrary expression cutoff.

Results

We apply spectral graph theory methods to develop a systematic method for threshold selection. …

Harmonic Analysis Of Input Current Of Single-Phase Controlled Bridge Rectifier, Michael Mccarty, Taufik, Andre Pratama, Makbul Anwari

Electrical Engineering

Harmonic analysis of input current of single phase uncontrolled rectifier is widely known. However, little has been known about harmonic of the input current of single phase controlled or thyristor rectifier. This paper presents such an analysis using the bridge configuration for the controlled rectifier circuit. Results obtained from mathematical derivation, computer simulation, and hardware measurements will also be discussed.

Efficiency Performance Analysis Of Series Loaded Resonant Converter, Michael Mccarty, Taufik, Andre Pratama, Makbul Anwari

Electrical Engineering

Series Loaded Resonant (SLR) converter is a well known topology typically used in kilowatt-range power supplies. The topology may operate in either continuous or discontinuous conduction modes whose switching properties are covered in many power electronic text books. However, information related to the actual converter’s efficiency for each conduction mode is lacking and thus will be addressed in this paper. The development of a lab scale SLR converter will be described along with results of computer simulation. Efficiency performance from hardware results for each conduction mode when output power and switching frequency are varied will also be discussed.

Meshscan: Fast And Efficient Handoff In Ieee802.11 Mesh Networks, Yin Chen, Mark Davis

Conference papers

Handoff delay is one of the major problems in Wireless Mesh Network (WMN) that needs to be solved in order to allow time-critical and real-time applications run continuously during handoff. We have developed a fast handoff scheme called MeshScan to provide a novel use of channel scanning latency by employing open system authentication. This scheme comprises two steps: firstly a client device takes advantage of the WMN architecture to maintain a list of active mesh nodes. Secondly when handoff is required, a client transmits Authentication Request frames to all mesh nodes (MNs) from the list instead of broadcasting Probe Request …

A Broadcast Approach For Fading Wiretap Channels, Yingbin Liang, Lifeng Lai, H. Vincent Poor, Shlomo Shamai (Shitz)

Electrical Engineering and Computer Science - All Scholarship

A (layered) broadcast approach is studied for the fading wiretap channel without the channel state information (CSI) at the transmitter. Two broadcast schemes, based on superposition coding and embedded coding respectively, are developed to encode information into a number of layers and use stochastic encoding to keep the corresponding information secret from an eavesdropper. The layers that can be successfully and securely transmitted are determined by the channel states to the legitimate receiver and the eavesdropper. The advantage of these broadcast approaches is that the transmitter does not need to know the CSI to the legitimate receiver and the eavesdropper, …

P300-Based Speller Brain-Computer Interface, Reza Fazel-Rezai

Electrical Engineering Faculty Publications

No abstract provided.

Defining And Implementing Commutativity Conditions For Parallel Execution, Milind Kulkarni, Dimitrios Prountzos, Donald Nguyen, Keshav Pingali

Department of Electrical and Computer Engineering Technical Reports

Irregular applications, which manipulate complex, pointer-based data structures, are a promising target for parallelization. Recent studies have shown that these programs exhibit a kind of parallelism called amorphous data-parallelism. Prior approaches to parallelizing these applications, such as thread-level speculation and transactional memory, often obscure parallelism because they do not distinguish between the concrete representation of a data structure and its semantic state; they conflate metadata and data.

Exploiting the semantic commutativity of methods in complex data structures is a promising approach to exposing more parallelism. Prior work has shown that abstract locks can be used to capture a subset of …

Reinforcement-Learning-Based Output-Feedback Control Of Nonstrict Nonlinear Discrete-Time Systems With Application To Engine Emission Control, Peter Shih, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning-based output adaptive neural network (NN) controller, which is also referred to as the adaptive-critic NN controller, is developed to deliver the desired tracking performance for a class of nonlinear discrete-time systems expressed in nonstrict feedback form in the presence of bounded and unknown disturbances. The adaptive-critic NN controller consists of an observer, a critic, and two action NNs. The observer estimates the states and output, and the two action NNs provide virtual and actual control inputs to the nonlinear discrete-time system. The critic approximates a certain strategic utility function, and the action NNs minimize the strategic utility …

An Improved Nonlinear Statcom Control For Electric Arc Furnace Voltage Flicker Mitigation, Atousa Yazdani, Mariesa Crow, Jianjun Guo

Electrical and Computer Engineering Faculty Research & Creative Works

Electric arc furnaces (EAFs) are prevalent in the steel industry to melt iron and scrap steel. EAFs frequently cause large amplitude fluctuations of active and reactive power and are the source of significant power-quality (PQ) disturbances. Static synchronous compensators (STATCOMs) provide a power-electronic-based means of embedded control for reactive power support and PQ improvement. This paper introduces a new nonlinear control for the STATCOM that provides significant reduction in EAF-induced aperiodic oscillations on the power system. This method is compared with traditional PI controls and has shown to have improved performance.

Evolution Of Chemical Structure During Silver Photodiffusion Into Chalcogenide Glass Thin Films, A. Kovalskiy, H. Jain, Maria Mitkova

Electrical and Computer Engineering Faculty Publications and Presentations

The change of chemical structure resulting after X–ray and photo-induced silver diffusion into chalcogenide glass (ChG) thin films is monitored by high resolution X-ray photoelectron spectroscopy (XPS). As₄₀S₆₀ and Ge₃₀Se₇₀ thin films, which are based on pyramids and tetrahedral structural units, are investigated as model materials. Survey, core level (As 3d, S 2p, Ge 3d, Ge 2p, Se 3d, Ag 3d_5/2, O 1s, C 1s) and valence band spectra have been recorded and analyzed. Reference point for the …

Energy-Efficient Multi-Key Security Scheme For Wireless Sensor Network, Sandeep Kolli, Maciej Jan Zawodniok

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes multi-key encryption scheme and engine architecture (MKE) that increases security and optimizes energy efficiency of sensor networks, while minimizing modifications to existing implementations. The scheme improves security of AES against correlation power analysis (CPA) attack by employing MKE engine, breaking the correlation between power consumption and the used key. Other schemes utilize complex hardware designs, for example by using the inhomogeneous s-boxes that reduce energy efficiency of the engine. In contrast, the proposed hardware engine uses a randomly sequence of few keys to encode subsequent blocks of a messages. Additionally, the scheme improves security of AES against …

Glenn Research Center Quantum Communicator Receiver Design And Development, Murad Hizlan, John D. Lekki, Binh V. Nguyen

Electrical and Computer Engineering Faculty Publications

We investigate, design, and develop a prototype real-time synchronous receiver for the second-generation quantum communicator recently developed at the National Aeronautics and Space Administration (NASA) Glenn Research Center. This communication system exploits the temporal coincidences between simultaneously fired low-power laser sources to communicate at power levels several orders of magnitude less than what is currently achievable through classical means, with the ultimate goal of creating ultra-low-power microsize optical communications and sensing devices. The proposed receiver uses a unique adaptation of the early-late gate method for symbol synchronization and a newly identified 31-bit synchronization word for frame synchronization. This receiver, implemented …

Current Sensing For Automotive Electronics -- A Survey, Asha Patel, Mehdi Ferdowsi

Electrical and Computer Engineering Faculty Research & Creative Works

Current sensing is widely used in power electronic applications such as dc-dc power converters and adjustable-speed motor drives. Such power converters are the basic building blocks of drivetrains in electric, hybrid, and plug-in hybrid electric vehicles. The performance and control of such vehicles depend on the accuracy, bandwidth, and efficiency of its sensors. Various current-sensing techniques based on different physical effects such as Faraday's induction law, Ohm's law, Lorentz force law, the magnetoresistance effect, and the magnetic saturation effect are described in this paper. Each technique is reviewed and examined. The current measurement methods are compared and analyzed based on …

Estimation Of Channel Transfer Function And Carrier Frequency Offset For Ofdm Systems With Phase Noise, Jun Tao, Jingxian Wu, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

The joint estimation of carrier frequency offset (CFO) and channel transfer function (CTF) for orthogonal frequency-division multiplexing (OFDM) systems with phase noise is discussed in this paper. A CFO estimation algorithm is developed by exploring the time-frequency structure of specially designed training symbols, and it provides a very accurate estimation of the CFO in the presence of both unknown frequency-selective fading and phase noise. Based on the estimated CFO, phase noise and frequency-selective fading are jointly estimated by employing the maximum a posteriori (MAP) criterion. Specifically, the fading channel is estimated in the form of the frequency-domain CTF. The estimation …

Towards Supervised Autonomous Task Completion Using An In Vivo Surgical Robot, Jason J. Dumpert

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Laparoscopy is a minimally invasive alternative to traditional abdominal surgery. Unlike traditional surgery, a laparoscopic procedure can be completed using small incisions. The use of these small incision results in reduced pain to the patient, shorter recovery times, and less trauma to skin, muscle and other tissues. However, these benefits to the patient are offset by the increased difficulty to the surgeon performing the procedure. These difficulties include reduced dexterity, reduced perception, and longer procedure times. The use of small in vivo robotic devices in minimally invasive surgery is one possible solution to these problems. The movement of these devices …

Effects Of Gaussian Fields On The Stability Of Inhomogeneously Broadened Lasers, Pitak Chenkosol, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

Under some conditions, spontaneous coherent pulsations are known to occur in the output beams of inhomogeneously broadened laser oscillators. These lasers typically operate with a Gaussian transverse field distribution, while the corresponding theoretical models assume a uniform-plane-wave field. The effects of a Gaussian field on the stability criteria of single-mode inhomogeneously broadened ring laser oscillators are considered in this study. It is found that in comparison to a plane wave a Gaussian field variation still permits low-threshold spontaneous pulsations but reduces the parameter space over which these pulsations can be observed.

Power Efficiency Of Cooperative Communication In Wireless Sensor Networks, Sunita Gupta, Mehmet C. Vuran, M. Cenk Gursoy

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, a new protocol termed CoopXLM that integrates cooperative communication and Cross-Layer Module (XLM) is created and examined via simulation. CoopXLM modifies XLM by allowing multiple cooperative nodes to participate in receiver-based contention. Although there is increased energy consumption for processing, simulation results indicate that across all duty cycles there is an average energy savings of 38% with CoopXLM in comparison to XLM. It was also found that CoopXLM yields higher goodput than XLM at lower duty cycles but yields lower goodput at higher duty cycles.