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Articles 14581 - 14610 of 21740

Full-Text Articles in Engineering

Dc Link Stabilized Field Oriented Control Of Electric Propulsion Systems, Keith Corzine, S. D. Sudhoff, Steven F. Glover, H. J. Hegner, H. N. Robey Jan 1998

Dc Link Stabilized Field Oriented Control Of Electric Propulsion Systems, Keith Corzine, S. D. Sudhoff, Steven F. Glover, H. J. Hegner, H. N. Robey

Electrical and Computer Engineering Faculty Research & Creative Works

Induction motor based electric propulsion systems can be used in a wide variety of applications including locomotives, hybrid electric vehicles, and ships. Field oriented control of these drives is attractive since it allows the torque to be tightly and nearly instantaneously controlled. However, such systems can be prone to negative impedance instability of the DC link. This paper examines this type of instability and sets forth a readily implemented albeit nonlinear control strategy to mitigate this potential problem.


Total Quality Management And Corporate Financial Performance: An Analysis Of The Malcolm Baldridge National Quality Award Criteria, Alice Brigid Beechner Jan 1998

Total Quality Management And Corporate Financial Performance: An Analysis Of The Malcolm Baldridge National Quality Award Criteria, Alice Brigid Beechner

Doctoral Dissertations

"The impact of the Malcolm Baldrige National Quality Award (MBNQA) Performance Excellence Criteria on corporate financial performance is examined. Three independent studies were performed to assess this relationship. The first included Malcolm Baldrige National Quality Award (MBNQA) winners. The second study involved 69 firms identified as Total Quality Management (TQM) firms and for the final study a sample of large American corporations who completed surveys which provided an estimate of the score the companies would have received on a MBNQA assessment were examined. The method for assessing the financial strength for all three studies was the metric Market Value Added …


Spacing Of Connections In Compression Elements For Cold-Formed Steel Members (Beams), Michael L. Jones, Roger A. Laboube, Wei-Wen Yu Dec 1997

Spacing Of Connections In Compression Elements For Cold-Formed Steel Members (Beams), Michael L. Jones, Roger A. Laboube, Wei-Wen Yu

CCFSS Library (1939 - present)

PREFACE The spacing of connectors in compression elements of built-up flexural members was evaluated both experimentally and analytically at the University ofMissouri-Rolla (UMR) under the sponsorship of the American Iron and Steel Institute. A computational model was developed for determining the bending capacity of single-fluted sections with cover plates that do not have edge stiffeners. The results of the investigation are presented and recommendations are made for design of single-flute cross sections having cover plates without edge stiffeners. Previous research developments by Yener, at Purdue University, and Luttrell, at the University of West Virginia, were compared to the UMR experimental …


New Perspectives For Maximum Likelihood Time-Delay Estimation, John A. Stuller Dec 1997

New Perspectives For Maximum Likelihood Time-Delay Estimation, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

This Paper Introduces a New Realization for Maximum Likelihood Time-Delay Estimation (TDE) that Illuminates the Relationships between Maximum Likelihood TDE and Other Methods. We Obtain the Result by Deriving the Likelihood Function using a Fundamental Method that Appears to Be New to the Field of Array Processing. This Method is a Natural Complement to the Generalized Karhunen-Loève Expansion. © 1997 IEEE.


Real-Time And On-Line Near-Field Microwave Inspection Of Surface Defects In Rolled Steel, R. Zoughi, Christian J. Huber, Nasser N. Qaddoumi, Emarit Ranu, Vladimir Otashevich, Radin Mirshahi, Stoyan I. Ganchev, Thomas Johnson Dec 1997

Real-Time And On-Line Near-Field Microwave Inspection Of Surface Defects In Rolled Steel, R. Zoughi, Christian J. Huber, Nasser N. Qaddoumi, Emarit Ranu, Vladimir Otashevich, Radin Mirshahi, Stoyan I. Ganchev, Thomas Johnson

Electrical and Computer Engineering Faculty Research & Creative Works

The potential and limitations of near-field microwave inspection techniques for detecting various surface defects in rolled steel have been investigated. The focus of this study has been to investigate this potential for tin mill products containing gross and subtle defects including steel induced defects, roll marks, holes, scratches and gouges.


Analog Hardware Implementation Of Adaptive Filter Structures, Jui Kuo Juan, J. G. Harris, J. C. Principe Dec 1997

Analog Hardware Implementation Of Adaptive Filter Structures, Jui Kuo Juan, J. G. Harris, J. C. Principe

Electrical and Computer Engineering Faculty Research & Creative Works

We have implemented a four-tap adaptive filter in a continuous-time analog VLSI circuit. Since an ideal delay is impossible to implement in continuous-time hardware, we implemented the delay line as a cascade of low-pass filters (called the Gamma filter). Since many years of research in our lab has shown that the Gamma filter outperforms the delay line for a wide range of applications, the Gamma filter should not be considered merely a crude approximation of the ideal delay line. We show measured results from an analog chip that solves the problem of system identification-identifying an unknown linear circuit from its …


Absolute Measurements Of The High-Frequency Magnetic Dynamics In Hihg-Tc Superconductors, Stephen M. Hayden, Gabriel Aeppli, Pengcheng Dai, Herbert A. Mook, Toby G. Perring, S-W Cheong, Zachary Fisk, Fatih Dogan, Thomas E. Mason Dec 1997

Absolute Measurements Of The High-Frequency Magnetic Dynamics In Hihg-Tc Superconductors, Stephen M. Hayden, Gabriel Aeppli, Pengcheng Dai, Herbert A. Mook, Toby G. Perring, S-W Cheong, Zachary Fisk, Fatih Dogan, Thomas E. Mason

Materials Science and Engineering Faculty Research & Creative Works

We review recent measurements of the high-frequency dynamic magnetic susceptibility in the high-T~ superconducting systems La2-xSrxCuO4 and YBa2Cu3O6+x. Experiments were performed using the chopper spectrometers HET and MARI at the ISIS spallation source. We have placed our measurements on an absolute intensity scale; this allows systematic trends to be seen and comparisons with theory to be made. We find that the insulating S = ½ antiferromagnetic parent compounds show a dramatic renormalization of the spin wave intensity. The effect of doping on the response is to cause broadenings in …


Pseudogap And Incommensurate Magnetic Fluctuations In Yba2cu3o6.6, Pengcheng Dai, Herbert A. Mook, Fatih Dogan Dec 1997

Pseudogap And Incommensurate Magnetic Fluctuations In Yba2cu3o6.6, Pengcheng Dai, Herbert A. Mook, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Unpolarized inelastic neutron scattering is used to study the temperature and wave vector dependence of the dynamical magnetic susceptibility, X"(q, w), of a well-characterized single-crystal YBa2Cu3O6.6 (Tc = 62.7 K). We find that a pseudo gap opens in the spin-fluctuation spectrum at temperatures well above Tc. We speculate that the appearance of the low-frequency incommensurate fluctuations is associated with the opening of the pseudo gap. To within the error of the measurements, a gap in the spin-fluctuation spectrum is found in the superconducting state.


Pseudogap And Incommensurate Magnetic Fluctuations In Yba2cu3o6.6, Pengcheng Dai, Herbert A. Mook, Fatih Dogan Dec 1997

Pseudogap And Incommensurate Magnetic Fluctuations In Yba2cu3o6.6, Pengcheng Dai, Herbert A. Mook, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Unpolarized inelastic neutron scattering is used to study the temperature and wave vector dependence of the dynamical magnetic susceptibility X"(q,w) of a well-characterized single-crystal YBa2Cu3O6.6 (Tc = 62.7 K). We find that a pseudogap opens in the spin-fluctuation spectrum at temperatures well above Tc. We speculate that the appearance of the low-frequency incommensurate fluctuations is associated with the opening of the pseudogap. To within the error of the measurements, a gap in the spin-fluctuation spectrum is found in the superconducting state.


Milled Carbon Fiber Reinforced Polymer Composition, Brian Massengale, Paul Schauer, Charles Dahle, Barry Gregerson, Bonnie Bachman, Thomas Oesterle Nov 1997

Milled Carbon Fiber Reinforced Polymer Composition, Brian Massengale, Paul Schauer, Charles Dahle, Barry Gregerson, Bonnie Bachman, Thomas Oesterle

Economics Faculty Research & Creative Works

A milled carbon fiber reinforced polymer having increased abrasion resistive characteristics. The reinforced polymer comprises a base resin selected from the group consisting of polyolefins and polyamides. The base resin is combined with an amount of milled carbon fibers and further may be combined with polytetrafluoroethylene. The resulting composite materials have excellent friction and wear characteristics and are useful in the production of injection molded parts. The molded parts have a high impact strength, exhibit dimensional stability, are abrasion resistive, and are static dissipative, with the composite materials having particular utility as support fixtures for semiconductors during certain processing operations.


A Hybrid Fem/Mom Technique For Electromagnetic Scattering And Radiation From Dielectric Objects With Attached Wires, Mohammad Wares Ali, Todd H. Hubing, James L. Drewniak Nov 1997

A Hybrid Fem/Mom Technique For Electromagnetic Scattering And Radiation From Dielectric Objects With Attached Wires, Mohammad Wares Ali, Todd H. Hubing, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A hybrid formulation is presented, which combines the method of moments (MOM) with the edge-based vector finite element method (FEM) to solve electromagnetic radiation problems from structures consisting of an inhomogeneous dielectric body of arbitrary shape attached to one or more perfectly conducting bodies. While either method alone fails to model these structures efficiently, a combination of both finite element and moment methods provides an excellent way to solve these problems. The FEM is employed to handle the interior domain of inhomogeneous dielectric bodies and the method of moments is used to develop surface integrals that relate the field quantities …


Modeling Of Surface Hairline-Crack Detection In Metals Under Coatings Using An Open-Ended Rectangular Waveguide, Christian J. Huber, Habibollah Abiri, Stoyan I. Ganchev, R. Zoughi Nov 1997

Modeling Of Surface Hairline-Crack Detection In Metals Under Coatings Using An Open-Ended Rectangular Waveguide, Christian J. Huber, Habibollah Abiri, Stoyan I. Ganchev, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

A surface-breaking hairline crack or a narrow slot in a metallic specimen when scanned by an open-ended rectangular waveguide probe influences the reflection-coefficient properties of the incident dominant mode. Subsequent recording of a change in the standing-wave pattern while scanning such a surface results in what is known as the crack characteristic signal. Since microwave signals penetrate inside dielectric materials, this methodology is capable of detecting cracks under dielectric coatings of various electrical thicknesses as well. To electromagnetically model the interaction of an open-ended rectangular waveguide with a surface-breaking hairline crack under a dielectric coating, the dielectric-coating layer is modeled …


An Experimental Procedure For Characterizing Interconnects To The Dc Power Bus On A Multilayer Printed Circuit Board, Hao Shi, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Fei Sha Nov 1997

An Experimental Procedure For Characterizing Interconnects To The Dc Power Bus On A Multilayer Printed Circuit Board, Hao Shi, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Fei Sha

Electrical and Computer Engineering Faculty Research & Creative Works

The effectiveness of dc power-bus decoupling is impacted by the inductance associated with interconnect vias in printed circuit boards (PCB's). Adequate characterization of these interconnects is necessary to facilitate modeling and simulation, and to assess the effectiveness of added decoupling. In this study, a measurement procedure is presented for determining the series inductance and resistance of an interconnect with a network analyzer. The validity and limitations of the procedure are discussed. Experimental results of interconnect parameters on an 8 × 10 in ten-layer test-board corroborate those measured with a precision impedance analyzer. The measured interconnect values are used to simulate …


Quantifying Emi Resulting From Finite-Impedance Reference Planes, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Fei Sha, Cheung-Wei Lam, Lawrence Rubin Nov 1997

Quantifying Emi Resulting From Finite-Impedance Reference Planes, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Fei Sha, Cheung-Wei Lam, Lawrence Rubin

Electrical and Computer Engineering Faculty Research & Creative Works

Parasitic inductance in printed circuit board (PCB) geometries can detrimentally impact the electromagnetic interference(EMI) performance and signal integrity of high-speed digital designs. This paper identifies and quantifies the parameters that affect the inductance of some typical PCB geometries. Closed-form expressions are provided for estimating the inductances of simple trace and ground plane configurations.


Radiation Imaging Operators Applied To The Detection Of Velocity And Density Contrast Boundaries, Md. Ishfaqur Raza, Richard E. Dubroff, James L. Drewniak Nov 1997

Radiation Imaging Operators Applied To The Detection Of Velocity And Density Contrast Boundaries, Md. Ishfaqur Raza, Richard E. Dubroff, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A procedure for imaging interfaces formed by simultaneous density and velocity contrasts in acoustic media is described. The procedure is based on the properties of radiation imaging operators - a class of linear differential operators parametrically dependent on the acoustic properties of the media. An example of this procedure is demonstrated through the use of numerical simulation. Results, in the form of interface images, are shown, assuming the bulk acoustic characteristics (velocity and density) on both sides of the interface are known.


Increased Radiative Lifetime Of Rare Earth-Doped Zinc Oxyhalide Tellurite Glasses, David L. Sidebottom, Michael A. Hruschka, B. G. Potter, Richard K. Brow Oct 1997

Increased Radiative Lifetime Of Rare Earth-Doped Zinc Oxyhalide Tellurite Glasses, David L. Sidebottom, Michael A. Hruschka, B. G. Potter, Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

We have investigated the structural and optical properties of rare earth-doped zinc tellurite glasses modified by the substitution of ZnF2. Raman and phonon sideband spectroscopies were employed to characterize changes in the glass structure as well as to probe vibrational behavior in the immediate vicinity of the rare earth ion. These measurements are combined with photoluminescence and optical absorption to monitor the effect of halide substitution upon the optical behavior of the rare earth dopant. A substantial increase in the intrinsic radiative lifetime of Nd3+ is observed with increasing halide concentration.


Design And Implementation Of Digital Controllers For Smart Structures Using Field Programmable Gate Arrays, Jamie S. Kelly, Vittal S. Rao, Hardy J. Pottinger, H. Clifford Bowman Oct 1997

Design And Implementation Of Digital Controllers For Smart Structures Using Field Programmable Gate Arrays, Jamie S. Kelly, Vittal S. Rao, Hardy J. Pottinger, H. Clifford Bowman

Electrical and Computer Engineering Faculty Research & Creative Works

Implementation issues represent an unfamiliar challenge to most control engineers, and many techniques for controller design ignore these issues outright. Consequently, the design of controlled for smart structural systems usually proceeds without regard for their eventual implementation, thus resulting either in serious performance degradation or in hardware requirements that squander power, complicate integration, and drive up cost the level of integration assumed by the smart patch further exacerbates these difficulties, and any design inefficiency may render the realization of a single-package sensor-controller-actuator system infeasible. The goal of this research is to automate the controller implementation process and to relieve the …


An Empirical Relation Between The Mark-Houwink-Sakurada Constants, P. Rai, Stephen L. Rosen Sep 1997

An Empirical Relation Between The Mark-Houwink-Sakurada Constants, P. Rai, Stephen L. Rosen

Chemical and Biochemical Engineering Faculty Research & Creative Works

No abstract provided.


Optically Transparent Composite Material And Process For Preparing Same, D. E. Day, James O. Stoffer, John M. Barr Sep 1997

Optically Transparent Composite Material And Process For Preparing Same, D. E. Day, James O. Stoffer, John M. Barr

Materials Science and Engineering Faculty Research & Creative Works

Glass ribbon-reinforced transparent polymer composites which provide excellent optical transparency and a low distortion level over a wide temperature range while exhibiting superior mechanical properties as compared to non- reinforced polymer counterparts, and equivalent properties as compared to glass fiber-reinforced counterparts.


Adaptive Critic Designs, Danil V. Prokhorov, Donald C. Wunsch Sep 1997

Adaptive Critic Designs, Danil V. Prokhorov, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

We discuss a variety of adaptive critic designs (ACDs) for neurocontrol. These are suitable for learning in noisy, nonlinear, and nonstationary environments. They have common roots as generalizations of dynamic programming for neural reinforcement learning approaches. Our discussion of these origins leads to an explanation of three design families: heuristic dynamic programming, dual heuristic programming, and globalized dual heuristic programming (GDHP). The main emphasis is on DHP and GDHP as advanced ACDs. We suggest two new modifications of the original GDHP design that are currently the only working implementations of GDHP. They promise to be useful for many engineering applications …


A Parallel Genetic-Neuro Scheduler For Job-Shop Scheduling Problems, H. C. Lee, Cihan H. Dagli Aug 1997

A Parallel Genetic-Neuro Scheduler For Job-Shop Scheduling Problems, H. C. Lee, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

Despite relentless efforts on developing new approaches, there are still large gaps between schedules generated through various planning systems, and schedules actually used in the shop floor environment. An effective schedule generation is a knowledge intensive activity requiring a comprehensive model of a factory and its environment at all times. There are four main difficulties that need to be addressed. First, job shop scheduling belongs to a class of NP-hard problems. Second, it is a highly constrained problem that changes from shop to shop. Third, scheduling decisions depend upon other decisions which are not isolated from other functions. Thus, it …


A Guide For Designing With Standing Seam Roof Panels, American Iron And Steel Institute Aug 1997

A Guide For Designing With Standing Seam Roof Panels, American Iron And Steel Institute

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.


Ccfss Technical Bulletin August 1997, Wei-Wen Yu Center For Cold-Formed Steel Structures Aug 1997

Ccfss Technical Bulletin August 1997, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Technical Bulletins (1993 - 2020)

No abstract provided.


Ccfss News August 1997, Wei-Wen Yu Center For Cold-Formed Steel Structures Aug 1997

Ccfss News August 1997, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Newsletters (1999 - 2008)

No abstract provided.


Emi From Apertures At Enclosure Cavity Mode Resonances, Min Li, Yun Ji, S. Radu, Joe Nuebel, Wei Cui, James L. Drewniak, Todd H. Hubing, Thomas Van Doren Aug 1997

Emi From Apertures At Enclosure Cavity Mode Resonances, Min Li, Yun Ji, S. Radu, Joe Nuebel, Wei Cui, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

EMI from slots and apertures resulting from coupling of interior sources through enclosure cavity modes in a Sun S-1000 workstation was investigated. The excitation of a specially designed rectangular enclosure with a slot was also studied experimentally and with finite-difference time-domain (FDTD) simulations. The radiated power results for both the S-1000 and simple rectangular enclosure indicate that radiation at cavity mode resonance frequencies through slots and apertures can be as significant as at aperture or slot resonances. A decrease of the radiation through the slots and apertures can be achieved by employing a lossy material in the enclosure.


Identifying An Emi Source And Coupling Path In A Computer System With Sub-Module Testing, S. Radu, Yun Ji, Joe Nuebel, James L. Drewniak, Thomas Van Doren, Todd H. Hubing Aug 1997

Identifying An Emi Source And Coupling Path In A Computer System With Sub-Module Testing, S. Radu, Yun Ji, Joe Nuebel, James L. Drewniak, Thomas Van Doren, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

EMI in a workstation server resulting from CPU clock harmonics was investigated. Mechanisms by which noise is coupled off the CPU PCB module were diagnosed from studies and measurements on the CPU PCB alone. A model was then developed. Modifications were made and tested in the fully functional system to support the model.


An Expert System For Predicting Radiated Emi From Pcb's, Navin Kashyap, Todd H. Hubing, James L. Drewniak, Thomas Van Doren Aug 1997

An Expert System For Predicting Radiated Emi From Pcb's, Navin Kashyap, Todd H. Hubing, James L. Drewniak, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes an expert systems approach, based on symbolic reasoning techniques, to the problem of predicting radiated EMI levels from printed circuit boards. The expert system, currently under development at the University of Missouri-Rolla, USA, starts by extracting board geometry information from the board layout files. This information is fed into the classification algorithm, which determines the signal properties and nature of each net, using the knowledge stored in the knowledge base. The evaluation algorithm uses the available in formation to identify and evaluate critical circuit geometries, and then estimates the effect that these geometries have on system radiation …


Effects Of Gapped Groundplanes And Guard Traces On Radiated Emi, D. S. Britt, David M. Hockanson, Fei Sha, James L. Drewniak, Todd H. Hubing, Thomas Van Doren Aug 1997

Effects Of Gapped Groundplanes And Guard Traces On Radiated Emi, D. S. Britt, David M. Hockanson, Fei Sha, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Designers sometimes employ gapped reference planes to isolate analog and digital signals, and separate "quiet" and "noisy" ground structures by providing a series impedance. Guard traces are also used to reduce unwanted coupling to adjacent traces, which can lead to signal integrity or EMI problems. This study investigates the impact of gaps and guard traces on radiated EMI. A simple microstrip circuit was constructed to experimentally analyze the effects of groundplane gaps and guard traces.


Lumped-Element Sections For Modeling Coupling Between High-Speed Digital And I/O Lines, Wei Cui, Hao Shi, Xiao Luo, Fei Sha, James L. Drewniak, Thomas Van Doren, T. Anderson Aug 1997

Lumped-Element Sections For Modeling Coupling Between High-Speed Digital And I/O Lines, Wei Cui, Hao Shi, Xiao Luo, Fei Sha, James L. Drewniak, Thomas Van Doren, T. Anderson

Electrical and Computer Engineering Faculty Research & Creative Works

Lumped-element sections are used for modeling coupling between high-speed digital and I/O lines on printed circuit boards (PCBs) in this paper. Radiated electromagnetic interference (EMI) is investigated when the I/O line going off the board is driven as an unintentional, but effective antenna. Simulated results are compared with measurements for coupled lines. A suitable number of lumped-element sections for modeling is chosen based on the line length and the highest frequency of interest.


Numerical And Experimental Corroboration Of An Fdtd Thin-Slot Model For Slots Near Corners Of Shielding Enclosures, Min Li, Kuang-Ping Ma, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren Aug 1997

Numerical And Experimental Corroboration Of An Fdtd Thin-Slot Model For Slots Near Corners Of Shielding Enclosures, Min Li, Kuang-Ping Ma, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Simple design maxims to restrict slot dimensions in enclosure designs below a half-wave length are not always adequate for minimizing electromagnetic interference (EMI). Complex interactions between cavity modes, sources, and slots can result in appreciable radiation through nonresonant length slots. The finite-difference time domain (FDTD) method can be employed to pursue these issues with adequate modeling of thin slots. Subcellular FDTD algorithms for modeling thin slots in conductors have previously been developed. One algorithm based on a quasistatic approximation has been shown to agree well with experimental results for thin slots in planes. This FDTD thin-slot algorithm is compared herein …