Engineering Commons^™

Beam Modes Of Lasers With Misaligned Complex Optical Elements, Anthony A. Tovar

Dissertations and Theses

A recurring theme in my research is that mathematical matrix methods may be used in a wide variety of physics and engineering applications. Transfer matrix techniques are conceptually and mathematically simple, and they encourage a systems approach. Once one is familiar with one transfer matrix method, it is straightforward to learn another, even if it is from a completely different branch of science. Thus it is useful to overview these methods, and this has been done here. Of special interest are the applications of these methods to laser optics, and matrix theorems concerning multipass optical systems and periodic optical systems …

Molten Salt Electrolytes For Electrodeposition Of Cdte Films, Arif Raza, Robert Engelken, Brandon Kemp, Arees Siddiqui, Omer Mustafa

Journal of the Arkansas Academy of Science

We report preliminary investigation of several molten salt electrolytes containing CdCl2 and TeCl4 for the electrodeposition of CdTe films at temperatures well above (>250 °C) those used with aqueous and organic electrolytes. These high temperatures have potential todramatically increase the crystallite size (Poole, Engelken, et al., 1994), as is important for optoelectronic device applications of CdTe, a leading II-VIsemiconductor. This paper willsurvey the results obtained withelectrolytes such as B2O,/HBO2 (m.p. - 230'C), NaCH3COO (m.p. » 324°C), ZnCl2 (m.p. - 283*C), and LiCl/KCl (m.p. * 350 °C), with an emphasis on the latter two. Key material to be presented includes …

Polishing Of Cvd-Diamond Substrates Using Reactive Ion Etching, Gopi M.R. Sirineni, Hameed A. Naseem, W. D. Brown, A. P. Malshe

Journal of the Arkansas Academy of Science

Multichip modules (MCM)have proved to be a viable packaging technology for achieving small size and high performance. By their nature, MCMs typically integrate multiple bare die into a module that can be the plastic or ceramic package. As a result, the MCMrequires an efficient mechanism for removing excess heat. Diamond with its excellent thermal conductivity, is the ideal choice as a substrate material for these applications. Chemical vapor deposited (CVD) diamond substrates makes possible the practical realization of a novel diamond based 3-D MCM. However, the diamond films grown by CVD technique are polycrystalline and have non-uniform filmroughness and randomly …

Electrical Power Dispatch To Motors Using Digital Modulating Techniques, David Michael Canny

Theses

The trend towards digital and microprocessor based control of power electronic converters has increased the level of research into digital modulating techniques. This thesis examines the inherent digital nature of Binary Rate Modulation with particular attention concentrated on its suitability for dispatching power to three-phase loads. The circuit topology of a three-level inverter is also examined and its performance aspects are compared with those of the more conventional two-level inverter.

Integral cycle Binary Rate Modulation is applied to an ac voltage controller and this method of power dispatch, which displays an optimal ac cycle positioning property, is compared with Pulse …

Does Junk Dna Regulate Gene Expression In Humans, M. A. Hulten, Michael W. Stacey, S. J. Armstrong

Bioelectrics Publications

No abstract provided.

Electric Field Mapping System With Nanosecond Temporal Rosolution, F. E. Peterkin, R. Block, K. H. Schoenbach

Bioelectrics Publications

The electric field dependence of the absorption coefficient in semi‐insulating GaAs at the absorption edge was measured in a high‐voltage pulsed experiment. Pulse duration was kept below 50 ns in order to avoid thermal effects. A GaAs laser diode was used as a probe light source with wavelength varied from 902 to 911 nm. For fields up to 40 kV/cm the absorption coefficient increased from 3 to 17 cm⁻¹ at 902 nm, with smaller absolute increases evident at the longer wavelengths. Calculation from theory was consistent with this behavior. The spatial variation of the electric field was also recorded …

Using Matlab To Illustrate The 'Phenomenon Of Aliasing', Sol Neeman, Ph.D.

Engineering Studies Faculty Publications and Creative Works

The phenomenon of aliasing is important when sampling analog signals. In cases where the signal is bandlimited, one can avoid aliasing by ensuring that the sampling rate is higher than the Nyquist rate . But in cases where the signal is not bandlimited , aliasing is unavoidable if the signal is not filtered before it is sampled. It is then crucial to understand the phenomenon in order to estimate the distortion generated when the signal is reconstructed from its samples. Using the software package MATLAB by MathWorks, Inc ., two examples are presented. The first is a pure sinusoid which …

A Silicon Knife Design And Fabrication, Mingli Wang

Theses

In this thesis, the design and fabrication of a silicon knife is described. The device design is based on the principle of oxidation sharpening.

The knife is made from a silicon wafer and can be made to be any chosen length up to 150 mm. It was made with the same basic procedures used in semiconductor chip manufacturing. This type of processing/manufacturing results in a knife with a high degree of sharpness and smoothness compared with existing knife technology.

The knife fabrication plan combines IC processing, techniques including anisotropic and isotropic etching of silicon, plasma dry etching and chemical etching …

An Investigation Into Artificial Intelligence Based Generative Computer Process Planning, William Tereshkovich

Theses

The process planning function can be further optimized with the introduction of an intelligent software package such as an Artificial Intelligence based Generative Computer Process Planning System. An AI based CAPP system, also categorized as an expert system, provides the vital link between design and manufacture, a "bridge" of knowledge in the information chain of manufacturing engineering. With the increasing role of computers in the process planning function, planning has become easier, faster, and more efficient.

This thesis provides an explanation of the process planning function and how artificial intelligence will improve it. Topics in AI techniques and procedures, knowledge …

A General Method For The Inverse Kinematics Of Rotational Displacements In Spatial Mechanisms, John D. Kliminski

Theses

An iterative technique was developed to solve the inverse kinematics problem for the joint rotations in both closed-loop and open-loop spatial mechanisms and robotic manipulators in any prescribed configuration. The method is based on fixing one link in space and maneuvering the other links to form a closed chain, following an approximation of the actual physical assembly of the mechanism. In order to apply the same principle to both types of mechanisms, an open-loop mechanism was modeled as a closed-loop mechanism by creating a fictitious fixed link in the free space between the base and the end of the chain …

Thermoplastic Composites Of Recycled High Density Polyethylene And Recycled Tire Particles, James N. Mckirahan Jr.

Masters Theses

This study identified the mechanical properties and processibility of composite materials of recycled high density polyethylene (HDPE), recycled rubber tire particles, and/or ethyl co-vinyl acetate and poly (e-caprolactone). The composites were processed using a single screw extrusion system.

Three groups of experiments were conducted, on the composites in their extruded form to investigate the mechanical properties of ultimate tensile strength, percent elongation, and hardness. The first experiment investigated the effect of recycled rubber particle concentration in the composites up to 25 percent. The second experiment investigated the effect of recycled rubber particle size on the composites of recycled HDPE and …

Creep-Fatigue Life Prediction - A Ductility Model, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

Creep-fatigue life prediction methods are briefly reviewed. Phenomenological methods of life prediction are very popular, since they use several test and metallographic parameters in model formulation. They also require numerous test parameters determined from specialized tests. Requirements of phenomenological methods have been summarized. Ductility measurement and modeling aspects have been reviewed. A new model has been developed with the assumption that with increasing fatigue cycles the ductility gradually decreases and the specimen fails as a result of exhaustion of ductility. This has been achieved in terms of dynamic viscosity (product of stress and cycle time), equated with material toughness, which …

Merits Of The Production Volume Based Similarity Coefficient In Machine Cell Formation, Hamid Seifoddini, Manocher Djassemi

Industrial Technology and Packaging

In this paper, two types of similarity coefficients are compared: (1) the Jaccard's coefficient and (2) the production volume based coefficient. Each is used to form a cellular manufacturing system whose performance will be used as a measure of effectiveness of the similarity coefficient. The sum of intercellular and intracellular material handling costs is used as a criterion for performance evaluation.

Spinodals In A Polymer-Dispersed Liquid-Crystal, Chungsea Shen, Thein Kyu

College of Polymer Science and Polymer Engineering

Thermodynamic phase equilibria of a polymer dispersed liquid crystal (PDLC) consisting of
monomeric liquid crystals and a polymer have been investigated theoretically and experimentally.
The equilibrium limits of phase separation as well as phase transition of a PDLC system were
calculated by taking into consideration the Flory–Huggins (FH) theory for the free energy of mixing
of isotropic phases in conjunction with the Maier–Saupe ~MS! theory for phase transition of a
nematic liquid crystal. The correspondence between the Landau–de Gennes expansion and the
Maier–Saupe theory was found and the coefficients were evaluated. The calculation based on the
combined FH-MS theory predicted …

Influence Of Fabrication Technique On The Fiber Pushout Behavior In A Sapphire-Reinforced Nial Matrix Composite, R. Asthana, R. R. Bowman, Surendra N. Tewari

Chemical & Biomedical Engineering Faculty Publications

Directional solidification (DS) of ''powder-cloth'' (PC) processed sapphire-NiAl composites was carried out to examine the influence of fabrication technique on the fiber-matrix interfacial shear strength, measured using a fiber-pushout technique. The DS process replaced the fine, equiaxed NiAl grain structure of the PC composites with an oriented grain structure comprised of large columnar NiAl grains aligned parallel to the fiber axis, with fibers either completely engulfed within the NiAl grains or anchored at one to three grain boundaries. The load-displacement behavior during the pushout test exhibited an initial ''pseudoelastic'' response, followed by an ''inelastic'' response, and finally a ''frictional'' sliding …

Lntracrystalline Diffusion Of Benzene In Silicalite : Effect Of Structural Heterogeneity, Dhananjai B. Shah, Chang-Jie Guo, David T. Hayhurst

Chemical & Biomedical Engineering Faculty Publications

The sorption kinetics of benzene in silicalite have been measured gravimetrically using large silicalite crystals of sizes 350 µm × 105 µm × 105 µm and 270 µm × 70 µm × 70 µm in the temperature range 283–343 K. Experiments were performed under conditions that ensured isothermal operation with intracrystalline diffusion control. An analytical expression for the Darken's correction factor (δ In P/δ In a) was derived based on the Hill–de-Boer equation and was used to determine the variation of corrected diffusivity with concentration. The transport diffusivity varied significantly with the adsorbed-phase concentration but the …

Activity Coefficients Of Adsorbed Mixtures, Orhan Talu, Jianmin Li, Alan L. Myers

Chemical & Biomedical Engineering Faculty Publications

Experimental and simulated data for adsorption of gas mixtures on energetically heterogeneous surfaces like activated carbon and zeolites exhibit negative deviations from ideality. The deviations are large in some cases, with activity coefficients at infinite dilution equal to 0.1 or less. Similar molecules form ideal mixtures, but molecules of different size or polarity are nonideal. Equations for bulk liquid mixtures (Wilson, Margules, etc.) do not apply to isobars for adsorbed mixtures. A two-constant equation for activity coefficients as a function of composition and spreading pressure is in good agreement with theory, simulation, and experiment.

Partial Pixels: A Three-Dimensional Diffractive Display Architecture, Gregory P. Nordin, M. W. Jones, S. T. Kowel, J. H. Kulick, R. G. Lindquist, P. J. Nasiatka, A. Parker

Faculty Publications

We describe in detail the partial pixel architecture that permits the realization of three-dimensional (3-D) displays that are functionally equivalent to a real-time holographic stereogram. This architecture permits the simultaneous presentation of multiple stereoscopic images so that motion parallax is discernible in the resultant 3-D scene. The key innovation of the architecture is that each pixel is subdivided into partial pixels, which in turn can be implemented as individual diffraction gratings. We describe a static display that exhibits a 3-D image with one-dimensional motion parallax, thereby demonstrating key features of the architecture. A variety of partial pixel implementations are discussed …

The Influence Of Uranyl Hydrolysis And Multiple Site-Binding Reactions On Adsorption Of U(Vi) To Montmorillonite, James P. Mckinley, John M. Zachara, Steven C. Smith, Gary D. Turner

United States Department of Energy: Publications

Adsorption of uranyl to SWy- 1 montmorillonite was evaluated experimentally and results were modeled to identify likely surface complexation reactions responsible for removal ofuranyl from solution. Uranyl was contacted with SWy- 1 montmorillonite in a NaC104 electrolyte solution at three ionic strengths (I = 0.001, 0.01, 0.1), at pH 4 to 8.5, in a N_2(g) atmosphere. At low ionic strength, adsorption decreased from 95% at pH 4 to 75% at pH 6.8. At higher ionic strength, adsorption increased with pH from initial values less than 75%; adsorption edges for all ionic strengths coalesced above a pH of 7. A …

Kemod: A Mixed Chemical Kinetic And Equilibrium Model Of Aqueous And Solid Phase Geochemical Reactions, G. T. Yeh, G. A. Iskra, J. E. Szecsody, John M. Zachara, G. P. Streile

United States Department of Energy: Publications

This report presents the development of a mixed chemical Kinetic and Equilibrium MODel (KEMOD), in which every chemical species can be treated either as a equilibrium-controlled or as a kinetically controlled reaction. The reaction processes include aqueous complexation, adsorption/ desorption, ion exchange, precipitation/dissolution, oxidation/reduction, and acid/base reactions. Further development and modification of KEMOD can be made in: (1) inclusion of species switching solution algorithms, (2) incorporation of the effect of temperature and pressure on equilibrium and rate constants, and (3) extension to high ionic strength.

Alternative Approaches To On-Farm Research And Technology Exchange, Charles A. Francis, Victoria Mundy, Rhonda Janke, James King

CARI Extension and Education Materials for Sustainable Agriculture

Decision Case Studies are Ideal for On-Farm Research by R. Kent Crookston (University of Minnesota)

Use of On-Farm Research by Farmers for Technology Development and Transfer by Stewart Wuest, Baird Miller, Stephen Guy, Russ Karow, Rojer Veseth, and Donald Wysocki (Washington State University, University of Idaho, and Oregon State University)

Best Information for Choosing Crop Varieties by Dale Hicks and Robert Stucker (University of Minnesota)

Adaptability Analysis for Diverse Environments by Peter Hildebrand and John Russell (University of Florida and Washington State University)

Complementary Abilities and Objectives in On-Farm Research by Derrick Exner (Iowa State University)

Credibility of On-Farm Research …

Master Of Science Degree Programs Computer Information Systems, Management Information Systems 1995, Nova Southeastern University

College of Engineering and Computing Course Catalogs

No abstract provided.

Webwork: Integrated Programming Environment Tools For National And Grand Challenges, Geoffrey C. Fox, Wojtek Furmanski, Marina Chen, Claudio Rebbi, James H. Cowie

Physics - All Scholarship

Challenging-scale problems consistently demand solutions that fuse geographically distributed and heterogeneous data, personnel, expertise, and resources. For example, national health care problems require collaboration among experts of fields as diverse as medical informatics, public policy, robotics, and high performance computing to solve problems ranging from telemedicine to cost management and quality control. Indeed, many National Challenges include Grand Challenges as subcomponents. We can pose the Integrated Challenge as the solution of etaproblems hosted on world-wide metacomputers linking all three aspects: simulation, information processing, and collaboration. We suggest a hybrid approach to Integrated Challenges that combines World-Wide Web (WWW) technologies with …

Techniques For Scheduling I/O In A High Performance Multimedia-On-Demand Server, Divyesh Jadav, Chutimet Srinilta, Alok Choudhary, P. B. Berra

Electrical Engineering and Computer Science - All Scholarship

One of the key components of a multi-user multimedia-on-demand system is the data server. Digitalization of traditionally analog data such as video and audio, and the feasibility of obtaining network bandwidths above the gigabit-per-second range are two important advances that have made possible the realization, in the near future, of interactive distributed multimedia systems. Secondary-to-main memory I/O technology has not kept pace with advances in networking, main memory and CPU processing power. Consequently, the performance of the server has a direct bearing on the overall performance of such a system. In this paper we present a high-performance solution to the …

Runtime Support For In-Core And Out-Of-Core Data-Parallel Programs, Rajeev Thakur

Electrical Engineering and Computer Science - All Scholarship

Distributed memory parallel computers or distributed computer systems are widely recognized as the only cost-effective means of achieving teraflops performance in the near future. However, the fact remains that they are difficult to program and advances in software for these machines have not kept pace with advances in hardware. This thesis addresses several issues in providing runtime support for in-core as well as out-of-core programs on distributed memory parallel computers. This runtime support can be directly used in application programs for greater efficiency, portability and ease of programming. It can also be used together with a compiler to translate programs …

Obligations And Penalties Under Lemon Laws: Automobiles Versus Tractors, Terence J. Centner, Michael E. Wetzstein

Department of Agricultural Economics: Faculty Publications

Distinctive new provisions of tractor lemon laws which create obligations and provide penalties for defective self-propelled agricultural equipment are contrasted with provisions of automobile lemon laws. Lemon-law obligations involve both producers' guarantees to provide consumers with a serviceable vehicle and producers' promises to remedy defects. Due to fewer manufacturer obligations under the tractor lemon laws as opposed to automobile lemon laws, tractors may be expected to have more defects than automobiles. Yet the tractor lemon laws contain fewer penalties in the form of restitution remedies. The inconsistences of these obligations and penalties suggest tractor laws may be inefficient.

Visage: Improving The Ballistic Vulnerability Modeling And Analysis Process, Brett F. Grimes

Theses and Dissertations

The purpose of this thesis was to improve the process of modeling and analyzing ballistic vulnerability data. This was accomplished by addressing two of the more urgent needs of vulnerability analysts; the ability to display fault tree data and to edit target descriptions. A vulnerability data visualization program called VISAGE was modified to meet these needs. VISAGE was originally created to preview static shotline plots and subsequently grew into a full-featured visualization package for vulnerability target descriptions and analyses data. The next logical step in the programs evolution was to include the needed editing and fault tree display capabilities. The …

Regional Variation In Temperature Humidity Index For Poultry Housing, Richard S. Gates, Hanzhong Zhang, Donald G. Colliver, Douglas G. Overhults

Biosystems and Agricultural Engineering Faculty Publications

A building thermal model was used to compute hourly values of temperature humidity index (THI) for a broiler house with and without an evaporative misting system. Hourly summer time weather data for 238 U.S.A. locations covering 30 years were used to develop extreme occurrences of THI. Results were incorporated into a Geographical Information System (GIS) database to create isolines of THI and percentage of hours exceeding a heat stress threshold. Regional variations in misting as a suitable cooling technique are presented in terms of hours reduction in annual heat stress. The technique may be used for assisting in management decisions …

Test 1705: Ford 7740 Pulsecommand Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE

General

Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure.

The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

Test 1689: John Deere 8200 Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE

General

Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure.

The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …