Engineering Commons^™

Study Of Direct Semiconductor Materials For An Optically Controlled Switch, Sung Taek Ko

Electrical & Computer Engineering Theses & Dissertations

A model for a bulk GaAs photoconductive switch has been developed and solved to determine the performance of the device in closing and opening switch applications. The GaAs material has been characterized by deep level transient spectroscopy (DLTS). Two electron traps (EL2 and EL5) and one hole trap (Cu_B} have been detected and were included in the model. Simulation studies are performed on several GaAs switch systems composed of different combinations and density of deep levels to investigate the influence of deep traps in a photoconductive switch system. The electron occupancy of each deep trap is traced in …

Experimental Study Of Pressure And Heating Rate On A Swept Cylindrical Leading Edge Resulting From Swept Shock Wave Interference, Christopher E. Glass

Mechanical & Aerospace Engineering Theses & Dissertations

An experimental study of the effects of leading edge sweep on surface pressure and heat transfer rate for swept shock wave interference is presented. This study was conducted as a cooperative agreement between NASA Langley Research Center and Calspan-University of Buffalo Research Center. Experimental tests were conducted in the Calspan 48-inch Hypersonic Shock Tunnel at a nominal Mach number of 8, nominal unit Reynolds number of 1.5 x 10⁶ per foot, leading edge and incident shock generator sweep angles of 0^o, 15^o, and 30^o, and incident shock generator angle-of-attack fixed at 12.5^{o …}

Expert Systems For Automated Maintenance Of A Mars Oxygen Production System, Ming-Tsang Ho

Mechanical & Aerospace Engineering Theses & Dissertations

A prototype expert system has been developed for maintaining autonomous operation of a Mars oxygen production system. Normal operation conditions and failure modes according to certain desired criteria are tested and identified. Several schemes for failure detection and isolation using forward chaining, backward chaining, knowledge-based and rule-based are devised to perform several housekeeping functions. These functions include self-health checkout, an emergency shut down program, fault detection and conventional control activities. An effort has been made to derive the dynamic model of the system using Bond-Graph technique in order to develop the model-based failure detection and isolation scheme by estimation method. …

Irish Building Services News

Building Services Engineering

No abstract provided.

The Effects Of Nonlinearities On The Optimal Design Of Forced Vibrating Beams, Cheryl Celestine Jackson

Mechanical & Aerospace Engineering Theses & Dissertations

The optimal design of a beam under harmonic excitations is formulated and solved numerically for linear and nonlinear forced vibration theories. The beam has a nonuniform cross-sect ion, whose thickness can change during the optimization procedure. Based on the numerical results, for the given input frequency range, the linear vibration theory produces a more conservative design than the nonlinear vibration theory.

The analytical formulation for both theories is presented. For the linear case, a mean case is defined for the self-weight on a beam, and an alternating case is defined for input forcing frequencies which cause fatigue variations on a …

Low Speed Flowfield Characterization By Infrared Measurements Of Surface Temperatures, Ehud Gartenberg

Mechanical & Aerospace Engineering Theses & Dissertations

An experimental program was aimed at identifying areas in low speed aerodynamic research where infrared imaging systems can make significant contributions. Implementing a new technique, a long electrically heated wire was placed across a laminar jet. By measuring the temperature distribution along the wire with the IR imaging camera, the flow behavior was identified. Furthermore, using Nusselt number correlations, the velocity distribution could be deduced. The same approach was used to survey wakes behind cylinders in a wind-tunnel. This method is suited to investigate flows with position dependent velocities, e.g., boundary layers, confined flows, jets, wakes and shear layers. It …

Performance Modeling And Enhancement For The Atamm Data Flow Architecture, Sukhamoy Som

Electrical & Computer Engineering Theses & Dissertations

Algorithm To Architecture Mapping Model (ATAMM) is a new marked graph model from which the rules for data and control flow in a homogeneous, multicomputer, data flow architecture may be defined. This research is concerned with performance modeling and performance enhancement for periodic execution of large-grain, decision-free algorithms in such an ATAMM defined architecture. Performance measures and bounds are established. Algorithm transformation techniques are identified for performance enhancement and reduction of computing element requirements. Operating strategies are developed for optimum time performance and for sub-optimum time performance under limited availability of computing elements. An ATAMM simulator is used to test …

Model-Based Interpretation Of Time-Varying Medical Data, Michael G. Kahn, Lawrence M. Fagan Washington University In St. Louis, Lewis B. Sheiner Washington University In St. Louis

All Computer Science and Engineering Research

Temporal concepts are critical is medical therapy-planning. If given early enough, specific therapeutic choices may abort or suppress evolving undesired changes in a patient’s clinical status. Effective medical decision making demands recognition and interpretation of complex temporal changes that permeate the medical record. This paper presents a methodology for representing and using medical knowledge about temporal relationships to infer the presence of clinically relevant events, and describes a program, called TOPAZ, that uses this methodology to generate a narrative summary of such events. A unique feature of TOPAZ is the use of numeric and symbolic modeling techniques to perform temporal …

Acuta Enews April 1989, Vol. 18, No. 4

ACUTA Newsletters

In This Issue

President's Message

Party Line

User Groups

1989-90 Dues Notices

Gallaudet University

University of Missouri Adds Video Instruction To Beat The Highway Blue

Wake Forest University Telecommunitcations

Administrative Director's Office

Sky-high satisfaction with SkyDome contract

Acuta Enews March 1989, Vol. 18, No. 3

ACUTA Newsletters

In This Issue

Duke University Tel-Com

Bits & Pieces

President's Message

Administrative Director's Office

Palm Springs Seminar

Party Line

Digital Rebel

User Groups

Seely & Titlow Co. Building, Susie Van Kirk

Susie Van Kirk Papers

The building under consideration for historic designation is only part of what once constituted the Seely & Titlow Co. complex which included retail stores, offices, stockrooms, barns, and warehouses. A brief history of the business and the other buildings is necessary for understanding the history and significance of the 10th and I Street building.

Numerical Simulation Of F-18 Fuselage Forebody Flows At High Angles Of Attack, Lewis B. Schiff, Russell M. Cummings, Reese L. Sorenson, Yehia M. Rizk

Aerospace Engineering

As part of the NASA High Alpha Technology Program, fine-grid Navier-Stokes solutions have been obtained for flow over the fuselage forebody and wing leading edge extension of the F/A-18 High Alpha Research Vehicle at large incidence. The resulting flows are complex, and exhibit crossflow separation from the sides of the forebody and from the leading edge extension. A well-defined vortex pattern is observed in the leeward-side flow. Results obtained for laminar flow show good agreement with flow visualizations obtained in ground-based experiments. Further, turbulent flows computed at high-Reynolds-number flight-test conditions (M_∞ = 0.2, α = 30 °, and Re …

Modular Expansion Joints And Deck Drains, Theodore Hopwood Ii, Edgar E. Courtney

Kentucky Transportation Center Research Report

Inspections were conducted on bridge modular expansion joints and deck drains to assess their performance. Forty-four modular expansion joints were inspected including 38 Wabo-Maurer and 16 Acme joints. Twenty-three elastomeric dams were also inspected for comparative purposes including 21 Transflex dams and 2 Fei-Span units. The joints were rated using a quantitative subjective rating system developed by Penn DOT.

Both the modular expansion joints and the newer expansion dams were performing satisfactorily. Both types of joints leaked and experienced a number of minor hardware problems. some of the joints may warrant repairs to restore their complete function.

Deck drains and …

Design Of A Multiple Degree Of Freedom, Force Reflective Hand Master/Slave With A High Mobility Wrist, Tim Mclain, S C. Jacobsen, E K. Iversen, C C. Davis, D M. Potter

Faculty Publications

The Center for Engineering Design (CED) at the University of Utah has developed a force reflective, teleoperated multiple degree of freedom hand and high mobility wrist. This hand/wrist teleoperation system is targeted to perform dexterous manipulation and assembly tasks in an effort to approach the capabilities of a human. A first-stage prototype of this hand/wrist master/slave system, which is scheduled for laboratory demonstration in February of 1989, has nine actuated degrees of freedom in both the hand master and hand slave. This paper discusses elements of the design of this hand/wrist master and slave with particular emphasis on servo system …

Earthquake Hazard Mitigation Of Transportation Facilities For Mclean County, L. John Fleckenstein, David L. Allen, Vincent P. Drnevich

Kentucky Transportation Center Research Report

Concern has grown in recent years over the seismic activity of the New Madrid seismic zone in Western Kentucky. McLean County, Kentucky is located in this region. To permit emergency medical, supply, and equipment traffic into this area after an earthquake has occurred, the Kentucky Transportation Cabinet is interested in the possibility of keeping selected routes passable. This report lists the route that has been investigated and recommended as being the route in McLean County that should be maintained in passable condition. The recommended route, KY 136, has been visually surveyed and all seismically significant features cataloged. These features are …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, March 1989, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Evaluation Of Construction-Zone Pavement Marking Materials, Kenneth R. Agent, Jerry G. Pigman

Kentucky Transportation Center Research Report

The objectives of this study were to evaluate available foil-back and removable tapes as well as one new construction-zone raised pavement marker and to recommend materials that should be included on approved lists for use by the Kentucky Department of Highways. Tapes were placed on transverse test sections and the reflectivity, durability, and appearance were observed.

Tapes to be included on the approved lists for foil-back and removable tapes were recommended. Tapes manufactured by 3M, Flex-0-Lite, and Swarolite were included on the list of acceptable foil-back tapes. Recommended removable tapes were the 3M and Cataphote removable tapes. The Astra Optics …

Evaluation Of Mass Transport In Copper And Zinc Electrodeposition Using Tracer Methods, H. M. Wang, S. F. Chen, Thomas J. O'Keefe, M. Degrez, R. Winand

Materials Science and Engineering Faculty Research & Creative Works

Control of the electro crystallization process is essential in the deposition of metals from aqueous electrolytes. A knowledge of the influence of mass transfer on the metal ion reduction is a critical element in any number of electrolytic processes, particularly where relatively high current densities are desired. The use of more positive ion tracer techniques as a means of experimentally determining some of the mass transport properties of interest are described. Examples for copper, zinc and zinc alloys electrolysis are included. © 1989 Chapman and Hall Ltd.

The Nusat I Project: Government, Industry And Academia Learning Together, Charles A. Bonsall

Robert "Bob" Twiggs STEM Education Collection

A report composed by Charles A. Bonsall on the history of the NUSat Project in March of 1989.

Pump Pulse Effects In Synchronously Pumped Mode-Locked Dye Lasers, Duncan Leo Macfarlane, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

We consider the role of the pump pulse in the output of a synchronously pumped mode-locked dye laser. Our theoretical formalism is a nonlinear dynamical model that includes semiclassical effects, dipole orientation, and intrband relaxation. In particular, we study the shortenting of the output pulse with decreasing pump pulse length and increasing pump level. Both of these predictions agree with experiments.

Spontaneous Coherent Pulsations In Standing-Wave Laser Oscillators: Frequency Characteristics, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The output signal from a spontaneously pulsing laser must, by definition, consist of more than one frequency component. The experimental and theoretical study of the frequency components'associated with such a laser can provide valuable insights into the pulsation processes. The results of an investigation into the frequency characteristics of a spontaneously pulsing standing-wave laser are reported.

Stress Interference In A Transversely Isotropic Body Under Axisymmetric Loading, Stephen M. Heinrich, J. Y. Wang

Civil and Environmental Engineering Faculty Research and Publications

An unbounded homogeneous transversely isotropic body of revolution containing two twin spheroidal cavities is subjected to an axisymmetric loading. The axis of loading symmetry coincides with the axis of elastic symmetry of the material and the axis of revolution of the body. The elasticity solution is obtained in series form utilizing the displacement potential representation for the equilibrium of transversely isotropic solids, and numerical results are presented for the cases of two spherical cavities perturbing uniaxial and hydrostatic tension fields in certain hexagonal crystals and in isotropic materials. Of primary interest is the influence of cavity spacing and material type …

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 …

Management Strategies To Minimize And Reduce Soil Compaction, A. J. Jones, R. A. Wiese, Elbert C. Dickey

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Nature has some built-in processes that reduce soil compaction. They include cycles of wetting and drying, and freezing and thawing.

In the last 20 to 30 years, farming practices have changed drastically. These farming changes have made it more difficult for nature to rejuvenate the soil environment to an optimum condition for crops. Performing field operations on wet soils, using multiple field operations to grow the same crop continuously, and eliminating meadow crops from crop rotations contribute to more extensive and deeper compaction.

Each farmer has the opportunity to make decisions that can keep soils from becoming compacted.

Adoption of …

Computational Aspects Of Chance-Constrained Sustained Groundwater Yield Management, R. R.A. Cantiller, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

A methodology for including chance-constraints in models for maximizing regional sustained-yield groundwater extraction is presented. The procedure utilizes the spatially distributed mean and variance of saturated thickness in a confined aquifer. This data is derivable from kriging, a geostatistical technique. The technique is applied to a scenario of somewhat egalitarian agricultural development dependent on groundwater. Decision makers in this situation know that groundwater availability is insufficient to supply all potential demand. They plan to implement a sustained yield groundwater extraction strategy. They know that because of uncertain knowledge of aquifer parameters, at some point in the future, available groundwater in …

Condensation Coefficient Measurement For Water In The Umr Cloud Simulation Chamber, Donald E. Hagen, John L. Schmitt, Max B. Trueblood, John C. Carstens, Daniel R. White, Darryl J. Alofs

Physics Faculty Research & Creative Works

A systematic series of condensation coefficient measurements of water have been made using the University of Missouri-Rolla cooled-wall expansion chamber which simulates the thermodynamics of cloud. This coefficient is seen to decrease from a value near unity, at the outset of simulation, to a value in the neighborhood of 0.01 toward the end of a simulation. Final values of this coefficient are sufficiently low as to contribute significantly to the broadening of the drop-size distribution in cloud.

Impacts Of Industrial Robotics: Potential Effects On Labor And Costs Within The Metalworking Industries, Steven M. Miller

Research Collection School Of Computing and Information Systems

According to leading expert opinion, industrial robots are among the most important innovations of recent decades. Yet there is very considerable uncertainty (and disagreement) as to the rate at which the use of robots will spread and what their effects on employment, costs, and market structure will be. As stressed in 1983 by Congress’s Office of Technology Assessment: “A central question for an analysis of the social and economic impacts of programmable automation is whether programmable automation is likely to spread especially rapidly among firms and industries, and why.” The author analyzes the job displacement effects of industrial robots, as …

Application Of Hough Transformation To Detect Ovulatory Patterns In Cervical Mucus Images, Shiliang Wang

Dissertations and Theses

A microcomputer system called ovulocomputer is proposed. The system is used to predict and detect ovulation of women. It will use image processing and analysis, pattern recognition theory, spectrophotometry, ionometry and conductometry to measure various physical and chemical properties of cervical mucus that are related to blood hormone levels.

The functions and characteristics of cervical mucus are introduced in this thesis. Among them, the identification of cervical mucus images, named the ferning test, and related features, are well described.

A new idea, called ferning test automation, which has been neither proposed nor developed before, is presented and explained in detail …

Bulletin - February, 1989, Civil Aviation Medical Association

Browse all Civil Aviation Medical Association Newsletters

A six page newsletter of the Civil Aviation Medical Association. The newsletter provided news about civil aviation medicine and information related to the organization.

Thermal Performance Monitoring Results From The Residential Standards Demonstration Program, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

The Model Conservation Standards (MCS) were developed by the Northwest Power Planning Council in 1983. These standards were designed to save large amounts of space heating energy in new U.S. residential construction in the Pacific Northwest. Creation of the MCS resulted in a desire to demonstrate the actual savings of such energy efficiency standards. The Bonneville Power Administration sponsored the Residential Standards Demonstration Program (RSDP) in 1984 which resulted in the construction of 410 energy-efficient single-family homes in the four-state region. Typically these buildings incorporated design features such as high levels of insulation for attic, walls and floors, triple-glazed windows …