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Articles 1 - 16 of 16
Full-Text Articles in Engineering
Optimization Design Of Electrodes For Anode-Supported Solid Oxide Fuel Cells Via Genetic Algorithm, Junxiang Shi, Xingjian Xue
Optimization Design Of Electrodes For Anode-Supported Solid Oxide Fuel Cells Via Genetic Algorithm, Junxiang Shi, Xingjian Xue
Faculty Publications
Porous electrode is the critical component of solid-oxide fuel cells (SOFCs) and provides a functional material backbone for multi-physicochemical processes. Model based electrode designs could significantly improve SOFC performance. This task is usually performed via parameter studies for simple case and assumed property distributions for graded electrodes. When nonlinearly coupled multiparameters of electrodes are considered, it could be very difficult for the model based parameter study method to effectively and systematically search the design space. In this research, the optimization approach with a genetic algorithm is demonstrated for this purpose. An anode-supported proton conducting SOFC integrated with a fuel supply …
Error Correcting Codes For Cooperative Broadcasting, Robert H. Morelos-Zaragoza
Error Correcting Codes For Cooperative Broadcasting, Robert H. Morelos-Zaragoza
Faculty Publications
This talk considers the design and implementation of error correcting codes for cooperative broadcasting in wireless networks. Focus is on the case of two cooperating sources transmitting two classes of information to a single receiver. This case was first introduced in the seminal work of Bergmans and Cover and referred to as "over the air mixing". Two levels of protection are provided using two low-density parity-check (LDPC) codes combined using Plotkin's |u|u+v|-construction. Expressions are derived for the bit metrics used in iterative decoding for two-level codes combined with BPSK, QPSK and 4-PAM modulations. Several examples of codes and their performance …
Nonlinear Observability Analysis Of Bearing-Only Cooperative Localization Using Graph Theory, Rajnikant Sharma
Nonlinear Observability Analysis Of Bearing-Only Cooperative Localization Using Graph Theory, Rajnikant Sharma
Faculty Publications
In this report we investigate the nonlinear observability properties of bearing-only cooperative localization. We establish a link between observability and a graph representing measurements and communication between the robots.
Observability Analysis Of Bearing-Only Cooperative Localization, Rajnikant Sharma
Observability Analysis Of Bearing-Only Cooperative Localization, Rajnikant Sharma
Faculty Publications
In this report we investigate the nonlinear observability properties of bearing-only cooperative localization. We establish a link between observability and a graph representing measurements and communication between the robots. It is shown that graph theoretic properties like the connectivity and the existence of a path between two nodes can be used to explain the observability of the system.
Doping Dependence Of Electronic And Mechanical Properties Of Gase1−XTeX And Ga1−XInXSe From First Principles, Zs. Rak, S. D. Mahanti, K. C. Mandal, N. C. Fernelius
Doping Dependence Of Electronic And Mechanical Properties Of Gase1−XTeX And Ga1−XInXSe From First Principles, Zs. Rak, S. D. Mahanti, K. C. Mandal, N. C. Fernelius
Faculty Publications
No abstract provided.
Qpsk And Oqpsk In Frequency Nonselective Fading, Michael D. Rice
Qpsk And Oqpsk In Frequency Nonselective Fading, Michael D. Rice
Faculty Publications
The maximum likelihood estimator for the fading gain in a frequency non-selective fading channel is derived and analyzed for offset QPSK (OQPSK). The corresponding impact of estimator errors on the bit error probability performance for OQPSK is also derived.
The Electronic Structure And Secondary Pyroelectric Properties Of Lithium Tetraborate, Volodymyr T. Adamiv, Yaroslav V. Burak, David J. Wooten, John W. Mcclory, James C. Petrosky, Ihor Ketsman, Ya B. Losovyj, Peter A. Dowben, Jie Xiao
The Electronic Structure And Secondary Pyroelectric Properties Of Lithium Tetraborate, Volodymyr T. Adamiv, Yaroslav V. Burak, David J. Wooten, John W. Mcclory, James C. Petrosky, Ihor Ketsman, Ya B. Losovyj, Peter A. Dowben, Jie Xiao
Faculty Publications
We review the pyroelectric properties and electronic structure of Li2B4O7(110) and Li2B4O7(100) surfaces. There is evidence for a pyroelectric current along the [110] direction of stoichiometric Li2B4O7 so that the pyroelectric coefficient is nonzero but roughly 103 smaller than along the [001] direction of spontaneous polarization. Abrupt decreases in the pyroelectric coefficient along the [110] direction can be correlated with anomalies in the elastic stiffness contributing to the concept that the pyroelectric coefficient is not simply a vector but has qualities of …
A Miniature Energy Harvesting Device For Wireless Sensors In Electric Power System, Rashed H. Bhuiyan, Roger A. Dougal, Mohammod Ali
A Miniature Energy Harvesting Device For Wireless Sensors In Electric Power System, Rashed H. Bhuiyan, Roger A. Dougal, Mohammod Ali
Faculty Publications
A novel energy harvesting device called the energy coupler is proposed which can provide power to small wireless sensors in a power system. The energy coupler when coupled electromagnetically to a nearby current carrying conductor scavenges ac power from the conductor. The proposed energy coupler converts the harvested ac power into dc using a passive voltage multiplier circuit. The design of the energy coupler is such that the dc power obtained is adequate to charge a miniature 1.2-V rechargeable battery. It is demonstrated that the energy coupler is capable of delivering 10 mW of dc power to a 50-Ω load. …
Stochastic Feature Selection With Distributed Feature Spacing For Hyperspectral Data, Jeffrey D. Clark, Michael J. Mendenhall, Gilbert L. Peterson
Stochastic Feature Selection With Distributed Feature Spacing For Hyperspectral Data, Jeffrey D. Clark, Michael J. Mendenhall, Gilbert L. Peterson
Faculty Publications
Feature subset selection is a well studied problem in machine learning. One short-coming of many methods is the selection of highly correlated features; a characteristic of hyperspectral data. A novel stochastic feature selection method with three major components is presented. First, we present an optimized feature selection method that maximizes a heuristic using a simulated annealing search which increases the chance of avoiding locally optimum solutions. Second, we exploit local cross correlation pair-wise amongst classes of interest to select suitable features for class discrimination. Third, we adopt the concept of distributed spacing from the multi-objective optimization community to distribute features …
5 Ghz Band Vehicle-To-Vehicle Channels: Models For Multiple Values Of Channel Bandwidth, Qiong Wu, David W. Matolak, Indranil Sen
5 Ghz Band Vehicle-To-Vehicle Channels: Models For Multiple Values Of Channel Bandwidth, Qiong Wu, David W. Matolak, Indranil Sen
Faculty Publications
In Sen and Matolak's earlier paper, 5-GHz-band vehicle-to-vehicle (V2V) channel models were presented for channel bandwidths of 5 and 10 MHz. In this paper, we provide additional tapped delay line models for bandwidths of 1, 20, 33.33, and 50 MHz based upon the data used in Sen and Matolak's paper. We provide tables of channel parameters for five types of V2V channel classes and also include example tap correlation coefficients. Root-mean-square delay spread values are summarized, as are values of bandwidth for which the channel frequency correlation takes values of 0.7 and 0.5. As with the results from Sen and …
Summary Of Feedback Edge Set Papers, Jonathan Johnson
Summary Of Feedback Edge Set Papers, Jonathan Johnson
Faculty Publications
The problem of finding a set of edges F from a directed graph G = (V,E) such that the graph G0 = (V,E − F) contains no cycles is known as the feedback edge set (FES) problem or the feedback arc set problem. A related problem is the minimum feedback edge set problem, in which the feedback edge set F must be minimal. The feedback edge set problem has application in applying a common reliability technique called triple modular redundancy to FPGA circuit designs where configuration memory scrubbing is employed [1].
Reverberation-Chamber Test Environment For Outdoor Urban Wireless Propagation Studies, Helge Fielitz, Kate A. Remley, Christopher L. Holloway, Qian Zhang, Qiong Wu, David W. Matolak
Reverberation-Chamber Test Environment For Outdoor Urban Wireless Propagation Studies, Helge Fielitz, Kate A. Remley, Christopher L. Holloway, Qian Zhang, Qiong Wu, David W. Matolak
Faculty Publications
We introduce a test environment to replicate the well-known clustering of reflections in power delay profiles arising from late-time delays and reflections. Urban wireless propagation environments are known to exhibit such clustering. The test setup combines discrete reflections generated by a fading simulator with the continuous distribution of reflections created in a reverberation chamber. We describe measurements made in an urban environment in Denver, CO, that illustrate these multiple distributions of reflections. Our comparison of measurements made in the urban environment to those made in the new test environment shows good agreement.
Statistical Approach For Yield Optimization For Minimum Energy Operation In Subthreshold Circuits Considering Variability Issues, Md. Waliullah Khan Nomani, Mohab Anis, Goutam Koley
Statistical Approach For Yield Optimization For Minimum Energy Operation In Subthreshold Circuits Considering Variability Issues, Md. Waliullah Khan Nomani, Mohab Anis, Goutam Koley
Faculty Publications
The supply voltage (V-dd) and threshold voltage (V-th) are two significant design variables that directly impact the performance and power consumption of circuits. The scaling of these voltages has become a popular option to satisfy performance and low power requirements. Subthreshold operation is a compelling approach for energy-constrained applications where processor speed is less important. However, subthreshold designs show dramatically increased sensitivity to process variations due to the exponential relationship of subthreshold drive current with V-th variation and drastically growing leakage power. If there is uncertainty in the value of the threshold or supply voltage, the power advantages of this …
On Iterative Decoding Of Two-Level Superposition Codes For Cooperative Broadcasting Based On Qpsk And 4-Pam Constellations, Robert H. Morelos-Zaragoza
On Iterative Decoding Of Two-Level Superposition Codes For Cooperative Broadcasting Based On Qpsk And 4-Pam Constellations, Robert H. Morelos-Zaragoza
Faculty Publications
This paper considers iterative decoding of two-level superposition codes used in cooperative broadcasting over wireless networks. The coding scheme consists of two low-density parity-check (LDPC) codes combined using Plotkin's |u|u + v|-construction and provides two levels of error protection. Coding for cooperative broadcasting differs from conventional single-source broadcast coding. Instead of binary addition of subcode codewords performed by a single-source encoder, in superposition coding two modulated subcode sequences, produced by two coordinated and independent sources, are combined at the antenna of the receiver. Expressions are derived for the bit metrics, or log-likelihood ratio values, used by an iterative decoder for …
Wireless Sensor Network Radio Power Management And Simulation Models, Michael I. Brownfield, Theresa Nelson, Scott Midkiff, Nathaniel J. Davis Iv
Wireless Sensor Network Radio Power Management And Simulation Models, Michael I. Brownfield, Theresa Nelson, Scott Midkiff, Nathaniel J. Davis Iv
Faculty Publications
Wireless sensor networks (WSNs) create a new frontier in collecting and processing data from remote locations. The IEEE 802.15.4 wireless personal area network-low rate (WPAN-LR) WSNs rely on hardware simplicity to make sensor field deployments both affordable and long-lasting without maintenance support. WSN designers strive to extend network lifetimes while meeting application-specific throughput and latency requirements. Effective power management places sensor nodes (or motes) into one of the available energy-saving modes based upon the sleep period duration and the current state of the radio. The newest generation of WPAN-LR-based sensor platform radios operates at a 250 kbps data rate and …
Comparison Of Stabilization Methods For Fixed-Speed Wind Generator Systems, Mohammod Ali, Bin Wu
Comparison Of Stabilization Methods For Fixed-Speed Wind Generator Systems, Mohammod Ali, Bin Wu
Faculty Publications
Static Synchronous Compensator (STATCOM), Pitch control system, Braking Resistor (BR), and Superconducting Magnetic Energy Storage (SMES) have recently been reported as stabilization methods for fixed-speed wind generator systems. although the individual technologies are well documented, a comparative study of these systems has not been reported so far. This paper aims to fill in the gap, and provides a comprehensive analysis of these stabilization methods for fixed-speed wind generator systems. The analysis is performed in terms of transient stability enhancement, controller complexity, and cost. a novel feature of this work is that the transient stability analysis of wind generator system is …