Electrical and Computer Engineering Commons^™

Non-Cooperative Detection Of Ultra Wideband Signals, Brett D. Gronholz

Theses and Dissertations

Techniques for the non-cooperative (non-matched filter) detection of impulse-like ultra wideband signals using channelized receiver architectures are developed and evaluated. Each technique considered is modeled and simulations conducted to characterize detection performance, the results of which are compared with the detection performance of three receivers: the matched filter receiver, which provides optimum detection performance in AWGN; the radiometer, or energy detector; and the multi-aperture cross correlation receiver. It is shown that a channelized receiver (with no downconversion) can provide approximately 2.5 dB improvement over the radiometer when performing detection using the temporal-temporal matrix (TTM). The TTM processing technique provides the …

Using A Reply Path And Handshaking Protocol To Allow For Incentives With Mix-Net Servers, Timothy J. Atkinson, Marius C. Silaghi

Electrical Engineering and Computer Science Faculty Publications

Sending a message to a destination anonymously so that the destination cannot figure out who the originator was, and ensuring that the message reaches the destination untampered with, can be a difficult problem. Chaum's mix-net solves this problem but offers little motivation for a person to set up a mix-net server. This paper discusses a method that not only allows monetary payments as an incentive to create a public mix-net server, but also provides some fraud detection at the time a message is being sent. Also compared with other methods, the method described here can be considered reasonable from the …

Telerobotic Controller, Michael Fewless, George Slater, Steve Waldron

Honors Theses

Atelerobotic system allows a user to interact with an environment indirectly. Our project successfully creates a telerobotic environment between the Phantom 1.5 controller and the UMI RTX robotic arm. Utilizing the haptic features of the Phantom controller, a more realistic interaction was created between the telerobotic system and the user by providing sensory feedback. As the user manipulates the hand-controlled Phantom device, signals are sent via a parallel port to the personal computer. A real-time WIN32 application, utilizing the GHOST SDK library, reads the position of the Phantom controller's coordinates and calculates the corresponding motor positions of the UMI RTXrobotic …

Understanding And Improving Moment Method Scattering Solutions, Clayton Paul Davis

Theses and Dissertations

The accuracy of moment method solutions to electromagnetic scattering problems has been studied by many researchers. Error bounds for the moment method have been obtained in terms of Sobolev norms of the current solution. Motivated by the historical origins of Sobolev spaces as energy spaces, it is shown that the Sobolev norm used in these bounds is equivalent to the forward scattering amplitude, for the case of 2D scattering from a PEC circular cylinder. A slightly weaker relationship is obtained for 3D scattering from a PEC sphere. These results provide a physical meaning for abstract solution error bounds in terms …

Applications Of Power Electronics-Based Systems In Vehicular Technology: State-Of-The-Art And Future Trends, R. Jayabalan, Babak Fahimi, A. Koenig, Steven Pekarek

Electrical and Computer Engineering Faculty Research & Creative Works

Power electronics-Based systems and components have been increasingly used in land, air, and sea vehicles over the past decade. This has turned the vehicular products into a primary market for power electronics applications. Moreover, the existing trend in more electrification of the vehicles represents an even bigger potential for an increase in the existing demand. Although the primary incentive for introduction of multi-converter systems into vehicular technologies was to enhance fuel economy and environmental issues associated with vehicles; today, improvement of fault tolerance, cost, and compactness have boosted the motivation for development of the more electric vehicles. the use of …

Electrochemical Behaviours Of Hemoglobin-Ddab-Modified Powder Microelectrode And The Application Of The Powder Microelectrode In Determination Of Nitric Oxide, Zhi-Mou Guo, Huan Liu, Jian Chen, Wen-Ting Zhang

Journal of Electrochemistry

The electrochemical behaviours of DDAB-Hb-PME were studied in this paper. The (apparent) surface concentration of Hb was enhanced greatly by using the powder microelectrode (technique). NO reacts with Hb and absorbs on the surface of the modified carbon powder. Therefore, the output of the electrode was enhanced greatly by employing PME with higher reaction surface (area). The sensitivity of DDAB-Hb-PME is 3.1 mA/μmol·L^-1·cm², which is much larger than the values obtained with the traditional electrodes. The detection limit is 9 nmol·L^-1 and the linear response range is 9～100 nmol·L^-1.

Improvement And Its Mechanism Of Storage Performance Of Ni-Mh Battery, Xiao-Feng Li, Li-Ping Ma, Yu-Wan Lou, Feng Li, Bao-Jia Xia

Journal of Electrochemistry

The storage performance of nickel-metal-hydride (Ni-MH) battery was studied by using galvanostatic charge-discharge and cyclic voltammetry. The experimental results indicated that CoOOH could not be completely restored after its being thoroughly reduced at lower potential, which might weaken electric conduction network in the positive electrode and result in fading of electrochemical properties of Ni-MH battery. Addition of nickel powder as a conductive agent into the positive electrode was beneficial to the capacity recovery after storage.

Effect Of Fe3+ Dopen Of Titanium Dioxide Film On Absorption Spectra And Photo Catalysis, Mei-Qun Xiao, Jia-Nian Shen, Moucheng Li, Peng-Fei Wu, Dong Liu, Yu-Juan Zhang

Journal of Electrochemistry

Photo-catalytic titanium dioxide film in nano crystalline has been prepared by electrochemical oxidation process and adding different amount of ferric ion into the electrolyte during the anodic oxidation.The effects of Fe³⁺ dopen on absorption spectra and photo-catalytic of the titanium dioxide films have been studied. It shows that the Fe³⁺ dopen caused the red shife of the absorption edge for the incoming light and exhibited the improved photocatalytic reactivity.

LicoXNi1-XO2 Cathode Materials Prepared By Electrolysis Of Co And Ni, Jin-Ping Wei, Xin Sun, Xiao-Yu Wang, Xi-Kui Bian, Jin-Ling Zhai, Yan-Jie Yan-Jie

Journal of Electrochemistry

A new electrolytic method was developed to prepare LiCo_xNi_1-xO₂ as a cathode material of lithium-ion battery. Contrary to the traditional method, electrolytic method is a potential method with simple process to industrialization and no pollution. Metal cobalt and nickel were electrolysed in parallel to prepare the precursor of Co_xNi_{1- x}(OH)₂.Different compositional precursors could be conveniently prepared by changing electrolytic current. The LiCo_0.3Ni_0.7O₂ cathode prepared by this method was found favorable charge-discharge and cycle properties. For the LiCo_0.3Ni_0.7O₂ cathode material, …

Anodic Dissolution Of Aluminum In Koh-Ethanol Solutions, Hai-Bo Shao, Jian-Ming Wang, Xiao-Yan Wang, Yi Zheng, Jian-Qing Zhang

Journal of Electrochemistry

The feasibility of employing aluminum in KOH ethanol solution as a battery anode system was discussed. Weight loss measurement showed that the corrosion rate of Al is low enough to be used in sealed batteries. Through the measurements done by anodic polarization, EIS and galvanostatic discharge, it was found that Al is electrochemical active in a wide potential range in this system, and its discharge mechanism is similar to that of Al in aqueous solution. The discharge potential increased rapidly after a period of time, which might be caused by the discharge products depositing on the electrode surface.

Preparation And Photo-Catalyst Properties Of The α-Fe2O3-Tio2 Films On Sodium Alginate Polymer, Li-Qin Chen, Huai-Zhen Zhong, Ri-Yao Chen, Xi Zheng, Zhen Chen

Journal of Electrochemistry

Three new nano thin films of α-Fe₂O_3, TiO₂ and α-Fe₂O₃-TiO₂ by doping their powder with sodium alginate polymer were prepared. Surface structure and catalytic activities of the films were characterized by FTIR, XRD, PL, TEM and I-V techniques. The results of UV-visible absorption showed that the methylene blue was mineralized in aqueous of α-Fe₂O₃/SA, TiO₂/SA and (α-(Fe₂O₃))-TiO₂ /SA upon radiation with ultra violet light. α-Fe₂O₃ enhanced their photo-decolorized-activities by doping 15% TiO₂.

Applications Of New Activated Carbon Meterials In The Electric Double-Layer Capacitor, Jian-Jun Zhang, Hua Jiang, Jian-Hui Fang, Li-Yi Shi, Ren-He Yin, Yi Wen, Ji-Quan Liu

Journal of Electrochemistry

A new type activated carbon whose precursor was coconut shell could be obtained using specific physics-chemistry activation, and the activated carbon was applied as the material of electrode in EDLC (electrical double-layer capacitor),which had a large specific capacitance, and could charge and discharged in some large currents. Carbon dioxide and acid were used to modify carbon,and the effects of post-treatment on surface area and pore volume were investigated. A moulding method which has influence on some properties of carbon electrode with PTFE additive was researched in the paper.

Electrocatalytic Performances Of Carbon Nanotube Air Electrode For Oxygen Reduction, Feng-Ming Zhao, Chun-An Ma

Journal of Electrochemistry

The air electrodes with different mass ratio of Pt/active carbon or carbon nanotube as catalyst layer material have been prepared. The electrocatalytic performances for oxygen reduction were evaluated by means of polarization curve and electrochemical impedance spectroscopy (EIS). The results disclosed that carbon nanotubes dealt with nitric acid in the catalyst layer had been improved obviously on the electrocatalytic activity. After the surface of carbon nanotube was oxygenated and aggraded with platinum, the catalyst had obviously effects on the electrocatalytic activity. The air electrode with the mass ratio of active carbon to Pt/carbon nanotube in 4∶1 showed better electrocatalytic activity, …

The Investigation Of Bafesi/C Alloy Composite As Anode Materials For Li-Ion Battery, Rui-Xiang Feng, Hua Dong, Xin-Ping Ai, Han-Xi Yang

Journal of Electrochemistry

A novel BaFeSi/C composite was prepared by mechanical ball milling, and lithium insertion reactions on the composite electrode were investigated by cyclic voltammetry , charge-discharge measurements, XRD and XPS spectroscopy. It is demonstrated that the capacity retention with indiscernible capacity decas during charge-discharge cycling. The improved cycling ability of the composite is suggested from a cooperative action by inactive FeSi₂ and BaSi₂ matrix and outer graphite shell, which both buffer the volumetric changes of the active Si phase and provide a good connection for electronic and ionic conduction during lithium insertion and extraction processes.

Design Of Cmos Four-Quadrant Gilbert Cell Multiplier Circuits In Weak And Moderate Inversion, Craig Timothy Remund

Theses and Dissertations

This thesis presents four-quadrant CMOS current-mode multiplier architectures based on the bipolar Gilbert cell multiplier architecture. Multipliers are designed using the CMOS subthreshold region to take advantage of the subthreshold exponential I-V relationship that closely matches bipolar modeling. It is discovered that biasing to remove drift current components and to address higher order effects such as ideality factor mismatch, threshold mismatch, body effect, and short channel effects, is important to provide a linear multiplier. It is also shown that distortion caused by device size mismatch and offset input currents can be used to cancel the distortion introduced by drift currents …

Kalman Consensus Strategies And Their Application To Cooperative Control, Randal Beard, Derek Kingston, Wei Ren

Faculty Publications

Sponsorship: AFOSR, NSF. In this paper, we propose discrete-time and continuous-time consensus update schemes motivated by the discrete-time and continuous-time Kalman filters. With certainty information encoded into each agent, the proposed consensus schemes explicitly account for relative confidence in the information that is communicated from each agent in the team. We show mild sufficient conditions under which consensus can be achieved using the proposed schemes in the presence of switching interaction topologies. The Kalman consensus scheme is shown to be input-to-state stable. We show how to exploit this fact in multi-agent cooperative control scenarios.

Polarimetric Temperature Sensor Using Core-Replaced Fiber, Benjamin L. Ipson

Theses and Dissertations

Optical fibers are increasingly being used to create sensing devices. The D-fiber has an elliptical core and exhibits birefringence. This birefringence can be used to create a polarimetric sensor. The elliptical core supports two orthogonal modes that have separate effective indices of refraction. The indices of refraction change with a change in temperature. Since the effective indices of refraction change differently for the two modes, the birefringence also changes. This change in birefringence can be seen as a change in detected power through the fiber through the use of polarizers. The fiber then becomes a temperature sensor. The sensitivity of …

Condition Monitoring Of Squirrel-Cage Induction Motors Fed By Pwm-Based Drives Using A Parameter Estimation Approach, Behrooz Mirafzal, F. Fateh, Chia-Chou Yeh, Richard J. Povinelli, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

Abstract:

A rotor condition monitoring technique is presented in this paper based on a parameter estimation approach. In this technique, the stator currents, voltages and motor speed are used as the input signals, where the outputs will be the rotor's inductance, resistance and consequently rotor time constant. This approach is verified by simulation of two different induction motor cases. These simulations are buttressed by experimental data obtained for a 2-hp induction motor in the case of healthy as well as one, three and five rotor bar breakages. In these tests, the induction motor was energized from a PWM-based drive, in …

Thermodynamic Modeling, Energy Equipartition, And Nonconservation Of Entropy For Discrete-Time Dynamical Systems, Wassim H. Haddad, Qing Hui, Sergey G. Nersesov, Vijaysekhar Chellaboina

Department of Electrical and Computer Engineering: Faculty Publications

We develop thermodynamic models for discrete-time large-scale dynamical systems. Specifically, using compartmental dynamical system theory, we develop energy flowmodels possessing energy conservation, energy equipartition, temperature equipartition, and entropy nonconservation principles for discrete-time, large-scale dynamical systems. Furthermore, we introduce a new and dual notion to entropy; namely, ectropy, as a measure of the tendency of a dynamical system to do useful work and grow more organized, and show that conservation of energy in an isolated thermodynamic system necessarily leads to nonconservation of ectropy and entropy. In addition, using the system ectropy as a Lyapunov function candidate, we show that our discrete-time, …

Simulation Of Gate Lag And Current Collapse In Gallium Nitride Field-Effect Transistors, N. Braga, R. Mickevicius, R. Gaska, M. S. Shur, M. Asif Khan, Grigory Simin

Faculty Publications

Results of two-dimensional numerical simulations of gate lag and current collapse in GaN heterostructurefield-effect transistors are presented. Simulation results clearly show that current collapse takes place only if an enhanced trapping occurs under the gate edges. Hot electrons play an instrumental role in the collapse mechanism. The simulation results also link the current collapse with electrons spreading into the buffer layer and confirm that a better electron localization (as in a double heterostructurefield-effect transistor) can dramatically reduce current collapse.

Annealing And Oxidation Of Silicon Oxide Films Prepared By Plasma-Enhanced Chemical Vapor Deposition, X. Y. Chen, Yongfeng Lu, L. J. Tang, Y. H. Wu, B. J. Cho, J. R. Dong, W. D. Song

Department of Electrical and Computer Engineering: Faculty Publications

We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiO_x, 0,x,2) films by high-vacuum annealing and dry oxidation. The SiO_x films were deposited by plasma-enhanced chemical vapor deposition at different nitrous–oxide/silane flow ratios. The physical and optical properties of the SiO_x films were studied as a result of high-vacuum annealing and thermal oxidation. X-ray photoelectron spectroscopy (XPS) reveals that the as-deposited films have a random-bonding or continuous-random-network structure with different oxidation states. After annealing at temperatures above 1000 °C, the intermediate Si continuum in XPS spectra (referring to the …

Real-Time Registration And Display Of Confocal Microscope Imagery For Multiple-Band Analysis, Scott E. Budge, A.M. Mayampurath, J.C. Solinsky

Electrical and Computer Engineering Faculty Publications

Multiple images acquired in real-time from a confocal microscope in different illumination wavebands are used to construct a three-dimensional understanding of living cell signal propagation. Registration, fusion, and display of these images are performed in real-time using field programmable gate array (FPGA) technology to allow the biological scientist to observe time critical signaling processes as they occur. The registration and display system operates at a rate of up to 15 frames/s, and performs dark offset correction and noise reduction, followed by non-linear correction for lens warp and focal plane tilt, and finally correction for spatial mismatch between the different wavebands. …

A Review Of Antennas And Propagation For Mimo Wireless Communications, Michael A. Jensen, Jon W. Wallace

Faculty Publications

Multiple-input-multiple-output (MIMO) wireless systems use multiple antenna elements at transmit and receive to offer improved capacity over single antenna topologies in multipath channels. In such systems, the antenna properties as well as the multipath channel characteristics play a key role in determining communication performance. This paper reviews recent research findings concerning antennas and propagation in MIMO systems. Issues considered include channel capacity computation, channel measurement and modeling approaches, and the impact of antenna element properties and array configuration on system performance. Throughout the discussion, outstanding research questions in these areas are highlighted.

Parametric Investigation Of Laser Nanoimprinting Of Hemispherical Cavity Arrays, L. P. Li, Yongfeng Lu, D. W. Doerr, Dennis R. Alexander, X. Y. Chen

Department of Electrical and Computer Engineering: Faculty Publications

A monolayer of self-assembled silica particles can be imprinted into a silicon substrate by laser irradiation (KrF excimer laser, λ=248 nm). Periodical hemispherical cavities can be therefore created on the substrate surface. The influences of various particle sizes and laser fluence were investigated. In addition, preheating of the substrate significantly improves the performance. One-dimensional thermal calculation was employed to understand the thermal effect in this process. Three-dimensional optical simulation provided an accurate insight into the light intensity enhancement. Raman spectroscopy was used to examine the stress induced by the laser imprinting process resided in the cavity structures.

Versatile Hardware And Software Tools For Educating Students In Power Electronics, Joshua M. Williams, James L. Cale, Nicholas D. Benavides, Jeff D. Wooldridge, Andreas C. Koenig, Jerry L. Tichenor, Steven D. Pekarek

Electrical and Computer Engineering Faculty Research & Creative Works

A new power electronics laboratory has been constructed at the University of Missouri - Rolla. Key components of the laboratory are a set of custom- designed hardware and software tools. the novel hardware tools include five mobile power electronics testbeds that each contain the semiconductor devices, gate-drive boards, voltage and current sensors, and computer interface connections required to study a wide range of circuit topologies and control techniques. Novel software tools include a set of virtual instruments used for control, data capture, and data analysis. a description of these tools, along with their use in power electronics courses, laboratory exercises, …

Resolution Scaling In Noncontact Scanning Impedance Imaging, Benjamin C. Green, Tao Shang, Jacey C. Morine, Hongze Liu, Stephen M. Schultz, Travis E. Oliphant, Aaron R. Hawkins

Faculty Publications

Noncontact scanning impedance imaging has been presented as a method to provide high resolution, high contrast images for a variety of material systems. This technique combines electrical impedance measurements with very high resolution scanning. This article reports on efforts to scale this technique down to the very important single micron range and reveals measurements for both thick and thin samples with a measured minimum resolution below 30 µm. A design for a shielded impedance probe applicable to this process is outlined and probes of several different sizes were made and tested. Fabrication of these impedance probes is explained and a …

Layered Unequal Loss Protection For Image Transmission Over Packet Loss Channels With Delay Constraints, Jianfei Cai, Xiangjun Li, Chang Wen Chen

Electrical Engineering and Computer Science Faculty Publications

In the case of high bit rate image transmission or having lots of packets, the FEC (forward error correction) encoding and decoding processes in the ULP (unequal loss protection) based schemes should be applied to individual packet groups instead of all the packets in order to avoid long processing delay. In this paper, we propose a layered ULP (L-ULP) scheme for fast and efficient FEC allocations among different packet groups and also within each packet group. The numerical results show that the proposed L-ULP scheme is quite promising for fast image transmission over packet loss networks.

Multiple Wavelet-Tree-Based Image Coding And Robust Transmission, Lei Cao, Chang Wen Chen

Electrical Engineering and Computer Science Faculty Publications

In this paper, we present techniques based on multiple wavelet-tree coding for robust image transmission. The algorithm of set partitioning in hierarchical trees (SPIHT) is a state-of-the-art technique for image compression. This variable length coding (VLC) technique, however, is extremely sensitive to channel errors. To improve the error resilience capability and in the meantime to keep the high source coding efficiency through VLC, we propose to encode each wavelet tree or a group of wavelet trees using SPIHT algorithm independently. Instead of encoding the entire image as one bitstream, multiple bitstreams are generated. Therefore, error propagation is limited within individual …

Joint Source-Channel Decoding For Mpeg-2 Video Transmission, Liuguo Yin, Weigang Chen, Jianhua Lu, Chang Wen Chen

Electrical Engineering and Computer Science Faculty Publications

Joint source-channel coding schemes have been proven to be effective ways for reliable multimedia communications. In this paper, a joint source-channel decoding (JSCD) scheme that combines the hidden Markov source (HMS) estimation and low-density parity-check (LDPC) coding is proposed for the standard MPEG-2 video transmission. The LDPC code of the proposed scheme has a near-Shannon-limit error-correcting capability, while the HMS estimator may accurately extract the residual redundancy within the MPEG-2 video stream without any prior information. Furthermore, with a joint iterative decoding algorithm, the estimated source redundancy may be well exploited by the LDPC decoder, and the channel decoding feedback …

Multiple-Description Image Coding With Distributed Source Coding And Side Information, Min Wu, Anthony Vetro, Chang Wen Chen

Electrical Engineering and Computer Science Faculty Publications

Multiple description coding (MDC) is a source coding technique that involves coding the source information into multiple descriptions. When these descriptions are transmitted over different channels in packet network or error-prone wireless environment, graceful degradation can be achieved even if part of descriptions are not received by the receiver. When MDC is applied to wavelet subband based image coding, it is possible to introduce correlation between the descriptions in each subband. In this paper, we consider using such a correlation as well as potentially error corrupted description as side information in the decoding to formulate the MDC decoding as a …