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Articles 3331 - 3360 of 3518
Full-Text Articles in Engineering
Growth Of Cdte And Cds/Cdte Heterojunctions On Metal Substrates By Spray Pyrolysis, Alok K. Berry, Jack L. Boone, Thomas P. Van Doren
Growth Of Cdte And Cds/Cdte Heterojunctions On Metal Substrates By Spray Pyrolysis, Alok K. Berry, Jack L. Boone, Thomas P. Van Doren
Electrical and Computer Engineering Faculty Research & Creative Works
Preliminary results of the spray pyrolysis of thin films of CdTe on metal substrates are reported. The films are hard and adhere well to the substrate. A n-CdS/p-CdTe rectifying junction is also grown completely by spray pyrolysis on the metallic substrate. The ability to produce p-n junctions using the inexpensive and simple procedure of spray pyrolysis may lead to a viable process for mass production of solar cells. © 1990.
Fixed Mode Elimination In Decentralized Control Systems Using Eigenvalue Sensitivities, Jorge R.B. Souza, Vittal S. Rao
Fixed Mode Elimination In Decentralized Control Systems Using Eigenvalue Sensitivities, Jorge R.B. Souza, Vittal S. Rao
Electrical and Computer Engineering Faculty Research & Creative Works
The knowledge of fixed modes plays an important role in the design of decentralized controllers for large scale systems. An approach based on a parametric sensitivity of eigenvalues is proposed to select the information to be exchanged between control stations in order to eliminate decentralized fixed modes. The procedure is illustrated with an example. © 1990.
The Parallel Implementation Of The Waveform Relaxation Method For Transient Stability Simulations, Marija D. Ilić, Mariesa Crow
The Parallel Implementation Of The Waveform Relaxation Method For Transient Stability Simulations, Marija D. Ilić, Mariesa Crow
Electrical and Computer Engineering Faculty Research & Creative Works
In this paper, the authors extend the results of their earlier paper on waveform relamtion (WR), which is a parallel algorithm for transient stability analysis. The WR algorithm is extended to a structure-preserving power system model in which the loads are retained. This results in a system of differential/ algebraic equations (DAEs). Power systems exhibit several unique dynamic properties which may be exploited in an advantageous manner by the WR algorithm. This leads to a greater computational efficiency than most other direct methods of simulation. This paper presents several theoretical results as well as computational results on parallel implementation.
Design Of Robust Controllers For Gas Turbine Engines, David E. Moellenhoff, Vittal S. Rao, Charles A. Skarvan
Design Of Robust Controllers For Gas Turbine Engines, David E. Moellenhoff, Vittal S. Rao, Charles A. Skarvan
Electrical and Computer Engineering Faculty Research & Creative Works
This paper describes robust controller design methodologies for gas turbine engines. A linear state variable model for the engine is derived using partial derivatives. The Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) and the Parameter Robust Linear Quadratic Gaussian (PRLQG) robust controller design methodologies have been used to design a controller for gas turbine engines. A new method is proposed by combining the features of LQG/LTR and PRLQG methods and yields good robustness properties with respect to both unstructured uncertainties in the frequency domain and structured parameter variations in the time domain. The new procedure is illustrated with the …
Reduced Order Robust Controllers For An Experimental Flexible Grid, Vittal S. Rao, M. Westerheide, Alok Das
Reduced Order Robust Controllers For An Experimental Flexible Grid, Vittal S. Rao, M. Westerheide, Alok Das
Electrical and Computer Engineering Faculty Research & Creative Works
A procedure for the design and implementation of reduced-order robust controllers for active vibration control on an experimental flexible grid structure is presented. The experimental structure consists of a 5-ft x 5-ft grid made of 2-in-wide, 1/8-in-thick aluminum strips. The grid hangs vertically, being cantilevered at the top to a large T-beam anchored to a cinder block wall. The grid structure is represented by a 75-degree-of-freedom finite-element model, and the controller uses three piezoelectric accelerometer sensors to command three Non collocated DC motor torquers. The modified balance-truncation model-reduction method is used to derive a control synthesis model. These reduced-order models …
Bundled Cable Parameters And Their Impact On Emi Measurement Repeatability, Todd H. Hubing
Bundled Cable Parameters And Their Impact On Emi Measurement Repeatability, Todd H. Hubing
Electrical and Computer Engineering Faculty Research & Creative Works
EMI (electromagnetic interference) test procedures specify that long cables should be bundled at their center in some circumstances. The author investigates the effect of cable bundling using analytical models and measurements. He examines how cable bundle parameters such as length and "tightness'' can affect the repeatability of the measurement. Simple models of a bundled cable suggest that relatively small changes in the geometry of the bundle can significantly affect the common-mode cable current. Parameters such as length, tightness, location and the number of turns determine the impedance of the bundle. As the impedance of the cable bundle changes, the resonant …
A Balancing Method For Reduced Order Modelling Of Unstable Systems, Rajiva Prakash, Vittal S. Rao
A Balancing Method For Reduced Order Modelling Of Unstable Systems, Rajiva Prakash, Vittal S. Rao
Electrical and Computer Engineering Faculty Research & Creative Works
Moore's balancing method of model reduction has many attractive properties and is used widely in practice. However, this method suffers from the drawback that it is not applicable for unstable systems. This paper introduces a balancing method of model reduction to overcome this problem. The proposed technique obtains the reduced order model by balancing and truncating frequency domain controllability and observability Gramians. Analytical treatment is given for associated properties of the Gramians, and the balancing and truncation steps of model reduction. A numerical example is used to demonstrate the new approach. © 1990.
Effect Of Central Station Photovoltaic Plant On Power System Security, Badrul H. Chowdhury
Effect Of Central Station Photovoltaic Plant On Power System Security, Badrul H. Chowdhury
Electrical and Computer Engineering Faculty Research & Creative Works
The value of photovoltaic (PV) plants to electric utilities is investigated under constraints of power system security. It is suggested that the generally adopted methods of analysis for determining the capacity credit, energy displacement, and production cost savings due to the PV plants have neglected the adverse conditions that may arise out of a random preselection of a substation where PV power is injected into the system. The author presents an extensive approach to determining the realistic value of a PV plant to the utility. The method consists of using a power flow algorithm to determine system conditions under specific …
Analysis Of Wind Power Integration With Power System Planning, Badrul H. Chowdhury
Analysis Of Wind Power Integration With Power System Planning, Badrul H. Chowdhury
Electrical and Computer Engineering Faculty Research & Creative Works
No abstract provided.
A Review Of Recent Advances In Economic Dispatch, Badrul H. Chowdhury, S. Rahman
A Review Of Recent Advances In Economic Dispatch, Badrul H. Chowdhury, S. Rahman
Electrical and Computer Engineering Faculty Research & Creative Works
A survey is presented of papers and reports that address various aspects of economic dispatch. The time period considered is 1977-88. Four related areas of economic dispatch are identified and papers published in the general areas of economic dispatch are classified into these. These areas are: optimal power flow, economic dispatch in relation to AGC, dynamic dispatch, and economic dispatch with nonconventional generation sources.
A Two-Dimensional Analog Vlsi Circuit For Detecting Discontinuities In Early Vision, John G. Harris, Christof Koch, Jin Luo
A Two-Dimensional Analog Vlsi Circuit For Detecting Discontinuities In Early Vision, John G. Harris, Christof Koch, Jin Luo
Electrical and Computer Engineering Faculty Research & Creative Works
A large number of computer vision algorithms for finding intensity edges, computing motion, depth, and color, and recovering the three-dimensional shape of objects have been developed within the framework of minimizing an associated "energy" or "cost" functional. Particularly successful has been the introduction of binary variables coding for discontinuities in intensity, optical flow field, depth, and other variables, allowing image segmentation to occur in these modalities. The associated nonconvex variational functionals can be mapped onto analog, resistive networks, such that the stationary voltage distribution in the network corresponds to a minimum of the functional. The performance of an experimental analog …
Generalized Smoothing Networks In Early Vision, Shih Chii Liu, John G. Harris
Generalized Smoothing Networks In Early Vision, Shih Chii Liu, John G. Harris
Electrical and Computer Engineering Faculty Research & Creative Works
Generalized smoothing networks have been developed which enforce smoothness constraints for any arbitrary level of derivative of the input data. Furthermore, discontinuities of any order of derivative can be detected by providing for continuous line processes. which selectively inhibit smoothing. Second- and higher-order networks are required for many problems in early vision; first-order networks are often unsatisfactory. Examples in surface interpolation, edge detection, and image segmentation are shown. Solution of these types of problems typically takes a prohibitive amount of time, even on supercomputers. A significant advantage of these proposed networks is that they can be mapped directly to analog …
Mocvd Of Cds Onto (111) Silicon Substrates, Jack L. Boone, Scott A. Howard, Don D. Martin, Gene Cantwell
Mocvd Of Cds Onto (111) Silicon Substrates, Jack L. Boone, Scott A. Howard, Don D. Martin, Gene Cantwell
Electrical and Computer Engineering Faculty Research & Creative Works
Thin films of CdS were grown onto (111) silicon substrates (wafers 2 in in diameter) by employing a horizontal, low-pressure MOCVD system. The observed growth of heteroepitaxial films occurred in the temperature range of 275-325 ±5 °C. The growth of polycrystalline samples with a high degree of preferred orientation occurred at temperatures above 325 ± 5 °C. The later films exhibited irregularly shaped surface pits about 1 μm in depth. These pits were observed by sectioning the substrates and examining them with an SEM; no significant crystallinity was apparent. X-ray analysis of an heteroepitaxial and a polycrystalline film via a …
Convergence Properties Of The Waveform Relaxation Method As Applied To Electric Power Systems, Marija D. Ilić, J. K. White, Mariesa Crow
Convergence Properties Of The Waveform Relaxation Method As Applied To Electric Power Systems, Marija D. Ilić, J. K. White, Mariesa Crow
Electrical and Computer Engineering Faculty Research & Creative Works
Several theoretical results are presented and simple examples examined in order to determine the suitability of waveform relaxation for transient power system simulation. This examination leads to two practical suggestions that can easily be satisfied for power systems. The first is to break the simulation interval into sections, the first of which should be narrow and be used to kill off errors in the initial guess that activate the stiff modes. The second is to partition the system into subsystems that are stable, as this not only aids convergence but ensures multirate numerical stability.
Anserlin. A Broad-Band, Low-Profile, Circularly Polarized Antenna, James L. Drewniak, P. E. Mayes
Anserlin. A Broad-Band, Low-Profile, Circularly Polarized Antenna, James L. Drewniak, P. E. Mayes
Electrical and Computer Engineering Faculty Research & Creative Works
A technique is presented for improving the performance of low-profile, circularly polarized (CP) radiating-line antennas. The essential elements of the technique pertain to establishing a single traveling wave on an annular sector of conducting strip that is positioned parallel and close to a large conducting surface. The antenna is named the annular sector, radiating-line (ANSERLIN) antenna. Using this technique, the impedance bandwidth becomes so large that it no longer has any bearing on the operating bandwidth. Instead, the pattern shape and axial ratio become the factors that limit the bandwidth. Both senses of circular polarization can be transmitted or received …
Algorithms For Multi-Channel Dtmf Detection For The We Dsp32 Family, Steven L. Grant, J. Hartung, G. L. Smith
Algorithms For Multi-Channel Dtmf Detection For The We Dsp32 Family, Steven L. Grant, J. Hartung, G. L. Smith
Electrical and Computer Engineering Faculty Research & Creative Works
The authors describe two DTMF (dual-tone multiple frequency) detection algorithms that are highly efficient in the use of both real time and memory. The first algorithm is based on linear prediction (LP) and can be used to implement up to 32 DTMF detectors on a single 25-MHz NMOS WE DSP32. Using a 50-MHZ WE CMOS DSP32C, up to 45 detectors can be implemented. The second algorithm is based on a slight modification of the Goertzel algorithm and can be used to implement up to 16 DTMF detectors on a single DSP32 and up to 32 detectors on a DSP32C. In …
Central-Station Photovoltaic Plant With Energy Storage For Utility Peak Load Leveling, Badrul H. Chowdhury
Central-Station Photovoltaic Plant With Energy Storage For Utility Peak Load Leveling, Badrul H. Chowdhury
Electrical and Computer Engineering Faculty Research & Creative Works
The impact of photovoltaic (PV) power generation with energy storage on the electric utility's load shape for load leveling purposes is explored. Results show that utilities employing battery storage for peak load shaving might benefit from use of photovoltaic power, the extent of its usefulness being dependent on the specific load shapes as well as the photovoltaic array orientations. Typical utility load shapes both in the eastern and in the western parts of the US are examined for this purpose. Although photovoltaic power generation seems to have a bigger impact on the load of the western utility, utilities in both …
Modeling The Electromagnetic Radiation From Electrically Small Table-Top Products, Todd H. Hubing, J. Frank Kaufman
Modeling The Electromagnetic Radiation From Electrically Small Table-Top Products, Todd H. Hubing, J. Frank Kaufman
Electrical and Computer Engineering Faculty Research & Creative Works
It is noted that the most difficult radiated electromagnetic interference (EMI) problems with table-top products often occur at frequencies where the maximum dimensions of the product are much smaller than a wavelength. Electrically small table-top products tend to be much more efficient radiation sources than dipole source models would predict, and the radiation is generally much more difficult to contain than other types of EMI source models indicated. The ways in which electrically small sources radiate are investigated, and a technique for modeling electrically small table-top products that have power or signal cables is proposed. The end-driven wire model is …
The Effect Of Cable Terminations On Emi Measurements, Todd H. Hubing
The Effect Of Cable Terminations On Emi Measurements, Todd H. Hubing
Electrical and Computer Engineering Faculty Research & Creative Works
The effects of using uncontrolled or undefined cable terminations during electromagnetic interference (EMI) measurements was investigated. Several different models are described along with corresponding measurements in order to illustrate how specific terminations can be used to achieve particular measurement goals. It is noted that until a well-defined method of terminating power and signal cables is introduced, the best the EMI test engineer can do is to be aware of the significance of common-mode terminations and try to avoid situations where the common-mode termination impedance is completely undefined or not repeatable.
Lqg/Ltr Controller Design Using A Reduced Order Model, Rajiva Prakash, Vittal S. Rao
Lqg/Ltr Controller Design Using A Reduced Order Model, Rajiva Prakash, Vittal S. Rao
Electrical and Computer Engineering Faculty Research & Creative Works
A specific robust controller design procedure, linear quadratic Gaussian with loop transfer recovery (LQG/LTR), is studied. LQG/LTR design using a reduced-order model is performed. The error due to the use of the reduced model is accounted for by computing multiplicative error. All closed right half plane modes of the given system are included in the reduced-order model. The reduced-order LQG/LTR controller design procedure is applied to the problem of lateral attitude control of a drone aircraft. The case study demonstrates the reduction/design steps for a practical problem.
Automatic Color Segmentation Of Images With Application To Detection Of Variegated Coloring In Skin Tumors, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker
Automatic Color Segmentation Of Images With Application To Detection Of Variegated Coloring In Skin Tumors, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker
Electrical and Computer Engineering Faculty Research & Creative Works
A description is given of a computer vision system, developed to serve as the front-end of a medical expert system, that automates visual feature identification for skin tumor evaluation. The general approach is to create different software modules that detect the presence or absence of critical features. Image analysis with artificial intelligence (AI) techniques, such as the use of heuristics incorporated into image processing algorithms, is the primary approach. On a broad scale, this research addressed the problem of segmentation of a digital image based on color information. The algorithm that was developed to segment the image strictly on the …
Free Carrier Density Profiling By Scanning Infrared Absorption, Jack L. Boone, Michael D. Shaw, Gene Cantwell, William C. Harsch
Free Carrier Density Profiling By Scanning Infrared Absorption, Jack L. Boone, Michael D. Shaw, Gene Cantwell, William C. Harsch
Electrical and Computer Engineering Faculty Research & Creative Works
A prototype instrument for making contactless measurements of free carrier concentration as a function of the surface coordinates has been developed. The instrument requires minimal sample preparation, and the measurements are nondestructive. Measurements are based upon the free carrier absorption of photons at a wavelength of 10.6 μm. The measurement sensitivity is determined by the ability to resolve small variations in the transmitted wave. These variations can be significantly influenced by changes in sample thickness. A scheme has been devised which eliminates thickness variations by rotating the sample through small angles to achieve a transmission maximum at each data point. …
Estimation Of X-Band Scattering Properties Of Tree Components, David E. Pitts, Gautam D. Badhwar, Eddie Reyna, R. Zoughi, Linkim Wu, Richard K. Moore
Estimation Of X-Band Scattering Properties Of Tree Components, David E. Pitts, Gautam D. Badhwar, Eddie Reyna, R. Zoughi, Linkim Wu, Richard K. Moore
Electrical and Computer Engineering Faculty Research & Creative Works
An X-band FM-CW very fine range resolution scatterometer was used to acquire backscattering data for individual branches for a number of tree species. Using a model to describe the scattering source function, dσ/dR = f(η, κ), and an experimental procedure for selected removal of plant parts, allows the estimation of η, the volume backscatter coefficient, and κ, the volume extinction coefficient. It is found that 1) leaves are strong attenuators as well as scatterers, 2) the albedo, ω = η/κ, at a given angle of incidence, is nearly independent of the tree type, 3) the tree …
Measurements Of Radar Backscatter From An Artificial Tree An Indication Of Azimuthal Variations And Polarisation Sensitivity Of Trees, Richard K. Moore, M. S. Osman, R. Zoughi
Measurements Of Radar Backscatter From An Artificial Tree An Indication Of Azimuthal Variations And Polarisation Sensitivity Of Trees, Richard K. Moore, M. S. Osman, R. Zoughi
Electrical and Computer Engineering Faculty Research & Creative Works
Measurements of radar backscatter from an artificial tree were made in the laboratory at 6 and 10 GHz at horizontal incidence. The system has resolution cylinder 18 cm in diameter and 11 cm long. The tree itself was only 30.5 cm high so about half the tree was within the beam. The scattering was azimuthally uniform. Tilted polarizations gave results favoring an angle corresponding with that of the branches. Measurements were made with and without leaves.
Linear State Variable Dynamic Model And Estimator Design For Allison 1406 Gas Turbine Engine, Vittal S. Rao, D. Moellenhoff, J. A. Jaeger
Linear State Variable Dynamic Model And Estimator Design For Allison 1406 Gas Turbine Engine, Vittal S. Rao, D. Moellenhoff, J. A. Jaeger
Electrical and Computer Engineering Faculty Research & Creative Works
This paper describes a procedure for developing a State Variable Model for the Allison T406 gas turbine engine. This linear model is useful for designing controllers using modern control techniques. The engine and V-22 rotor system is modeled around an operating point by using four state variables and one input variable. For a given power setting, it is observed that two linear models are sufficient to represent the engine dynamics over the entire flight envelope. A relationship between surge margin and the state variables is also developed. It is demonstrated that these linear models are useful in designing an estimator …
Simulation Of Photovoltaic Power Systems And Their Performance Prediction, S. Rahman, Badrul H. Chowdhury
Simulation Of Photovoltaic Power Systems And Their Performance Prediction, S. Rahman, Badrul H. Chowdhury
Electrical and Computer Engineering Faculty Research & Creative Works
A number of photovoltaic (PV) performance-analysis models are tested for their ability to estimate the AC power output and validated against historical observations from a PV test facility. A method to estimate meteorological parameters is developed for use in PV performance models for predicting future AC power output from a PV test site. Twelve such PV performance models are examined, and the PVFORM system analysis program and lifetime cost and performance models are extensively tested. These two models are tested using the typical meteorological year and the VPI model-generated estimates of long-term data. Performance prediction results are compared against actual …
A Discussion On The Diversity In The Applications Of Photovoltaic Systems, S. Rahman, Badrul H. Chowdhury, M. A. Khallat
A Discussion On The Diversity In The Applications Of Photovoltaic Systems, S. Rahman, Badrul H. Chowdhury, M. A. Khallat
Electrical and Computer Engineering Faculty Research & Creative Works
References on the diverse applications of photovoltaic (PV) systems around the world are classified. The classes presented are (i) stand-alone, (ii) grid-connected, (iii) PV-thermal, (iv) PV-wind, and (v) dedicated applications. 73 papers are cited and classified into these five categories including a brief summary of each paper. Out of these, 42 papers relate to grid-connected applications in many industrialized countries of the world. These papers reflect the importance given to such applications. Due to the rapidly changing nature of PV and related industries, only papers published during the last ten years are considered.
Distribution Automation For The Association Of Missouri Electric Cooperatives—A Statewide Evaluation Of Load Management, Jack F. Morris, Frank J. Kern
Distribution Automation For The Association Of Missouri Electric Cooperatives—A Statewide Evaluation Of Load Management, Jack F. Morris, Frank J. Kern
Electrical and Computer Engineering Faculty Research & Creative Works
Presented is an in-depth technical and economic feasibility study utilizing one- and two-way management systems for statewide load control and distribution automation. Included are 1) an evaluation of the generation and transmission load patterns of the state cooperatives and the determination of the amount of controllable load for use by a load management system, 2) an in-depth economic cost-benefit study as a result of implementing a load management system on a statewide basis, 3) communication alternatives for implementing the statewide load management and distribution automation system, 4) an investigation into using an existing statewide microwave communications system for direct load …
Simulation Of Communication Systems Using Personal Computers, William H. Tranter, Carl R. Ryan
Simulation Of Communication Systems Using Personal Computers, William H. Tranter, Carl R. Ryan
Electrical and Computer Engineering Faculty Research & Creative Works
Microcomputer simulation provides a powerful tool for computer-aided design and analysis of communication systems and requires a minimum of investment. Two different simulation examples are presented: a fixed topology simulation program for digital data links written in Pascal; and a simulation of an analog link using Fortran. These examples are followed by a consideration of the new 32-bit single-board computers and their potential impact on microcomputer simulation. © 1988 IEEE
Implementation Of Dsp Applications Using The At&T Dsp32 C Compiler And Application Library, J. Tow, J. Hartung, Steven L. Grant
Implementation Of Dsp Applications Using The At&T Dsp32 C Compiler And Application Library, J. Tow, J. Hartung, Steven L. Grant
Electrical and Computer Engineering Faculty Research & Creative Works
The authors briefly introduce the C compiler and the application library for the DSP32 digital signal processor (DSP). Several examples are shown that illustrate the ease of writing C programs for some common filtering applications. In most cases, a small real-time penalty is incurred by using C, rather than assembly language coding. Programming in C, however, allows a dramatic improvement in programmer productivity in terms of implementing, testing, and maintaining an application