Engineering Commons^™

Subgrade Resilient Modulus For Pavement Design And Evaluation, Woojin Lee, Nihal Chand Bohra, A. G. Altschaeffl, Thomas D. White

JTRP Technical Reports

No abstract provided.

Debonding In Pretensioned Beams-Precast Strands, Part 2: Simply Supported Tests, O. A. Abdalla, J. A. Ramirez, Robert H. Lee

JTRP Technical Reports

No abstract provided.

Strand Debonding In Pretensioned Beams - Precast Prestressed Concrete Bridge Girders With Debonded Strands - Continuity Issues, O. A. Abdalla, J. A. Ramirez, Robert H. Lee

JTRP Technical Reports

No abstract provided.

Mathematical Modeling Of The Formation Of Calcareous Deposits On Cathodically Protected Steel In Seawater, J. F. Yan, T. V. Nguyen, Ralph E. White, R. B. Griffin

Faculty Publications

A first principle mathematical model of the formation of calcareous deposits on a cathodically protected steel rotatingdisk electrode in seawater is presented. The model includes equations which transport phenomena, electrochemical reactions,precipitation reactions, and a homogeneous reaction involved in the formation of calcareous deposits on an electrodesurface. Predicted concentration profiles show that a high concentration of OH^– ions on the electrode surface leads to the formation of calcareous deposits. The calcareous deposits contain mostly CaCO₃, but the initial deposits are predicted to contain more Mg(OH)₂ than CaCO₃. The predicted calcareous deposits on the electrode surface …

Parametric Studies Of The Formation Of Calcareous Deposits On Cathodically Protected Steel In Seawater, J. F. Yan, Ralph E. White, R. B. Griffin

Faculty Publications

A first principle mathematical model has been used to study the effects of ocean environment and cathodic protection on the formation of calcareous deposits and their ability to reduce the cathodic current density. These parameters include applied potential, rotation speed, temperature, salinity, and depth. The results showed the applied potential strongly influences the formation of calcareous deposits and their ability to reduce the cathodic current density. Among the environmental factors, rotation speed has the most influence on the cathodic current density. Salinity slightly influences the cathodic current density over the range of interest. Temperature is much more influential than salinity …

A Water And Heat Management Model For Proton-Exchange-Membrane Fuel Cells, Trung V. Nguyen, Ralph E. White

Faculty Publications

Proper water and heat management are essential for obtaining high-power-density performance at high energy efficiency for proton-exchange-membrane fuel cells. A water and heat management model was developed and used to investigate the effectiveness of various humidification designs. The model accounts for water transport across the membrane by electro-osmosis and diffusion, heat transfer from the solid phase to the gas phase and latent heat associated with water evaporation and condensation in the flow channels. Results from the model showed that at high current densities (> 1 A/cm²) ohmic loss in the membrane accounts for a large fraction of the …

Design And Construction Of Maintainable Knowledge Bases Through Effective Use Of Entity-Relationship Modeling Techniques, William Yancey Pike

Retrospective Theses and Dissertations

The use of an accepted logical database design tool, Entity-Relationship Diagrams (E-RD), is explored as a method by which conceptual and pseudo-conceptual knowledge bases may be designed. Extensions to Peter Chen's classic E-RD method which can model knowledge structure used by knowledge-based applications are explored. The use of E-RDs to design knowledge bases is proposed as a two-stage process. In the first stage, and E-RD, termed the Essential E-RD, is developed of the realm of the problem or enterprise being modeled. The Essential E-RD is completely independent of any knowledge representation model (KRM) and is intended for the understanding of …

Automatic Color Segmentation Algorithms-With Application To Skin Tumor Feature Identification, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker, G. A. Hance

Electrical and Computer Engineering Faculty Research & Creative Works

Two color-image segmentation methods are described. The first is based on a spherical coordinate transform of original RGB data. The second is based on a mathematically optimal transform, the principal components transform (also known as eigenvector, discrete Karhunen-Loeve, or Hotelling transform). These algorithms are applied to the extraction from skin tumor images of various features such as tumor border, crust, hair scale, shiny areas, and ulcer. The results of this research will be used in the development of a computer vision system that will serve as the visual front-end of a medical expert system to automate visual feature identification for …

Nebraska Summary: S171 Massey Ferguson 3075, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Nebraska Summary: S145 Case-Ih 5250, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Test 1663: Case International 7150 And 7250 Diesels 18-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 1665: John Deere 7600 Powershift Diesel 19-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 1666: John Deere 7700 Powerquad 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 1673: John Deere 8970 Powersync Diesel 12 And 24 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 1668: John Deere 7800 Powerquad 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 …

Consumption And Loss Of Formaldehyde In Electroless Copper Plating, Peter John F. Sutch

Retrospective Theses and Dissertations

The objectives of this research were to quantify formaldehyde consumption due to plating and parasitic reactions and determine the magnitude and distribution of formaldehyde losses from the electroless copper plating process. Plating and rinse bath samples obtained from three electroless copper plating operations were analyzed for formaldehyde and copper in order to develop a mass balance analysis about the plating bath for periods of active production and no production. Fugitive air and stack releases of formaldehyde were estimated using emission factors developed from air sampling at the three facilities. It was determined that approximately 90% of the formaldehyde added to …

Computer Model For Predicting Aids Among Intravenous Drug Users, Daniel Berleant, R. Ron Goforth, Jun Yuan

Journal of the Arkansas Academy of Science

Intravenous drug abuse (IVDA) is an important cause of HIV transmission. Computer simulation is one way to understand and predict the spread of HIV infection among IVDAs. We design and simulate HIV infection among IVDAs and the impact of AIDS on this community, and thereby predict future IVDA population, HIV levels, AIDS levels, and AIDS deaths in this group. The HIV to AIDS, and AIDS to Death latencies are described by probability density functions (PDFs) in this model. Factors such as the recruit, quit, and normal death rate of IVDAs, are considered, as well as the infection and removal rates …

Semi-Insulating Polysilicon Hetero- And Isotype Junctions On Silicon, R. M. Ranade, S. S. Ang, W. D. Brown

Journal of the Arkansas Academy of Science

The effects of nitrogen trifluorideinthe gas stream during deposition of semi-insulating polysilicon (SIPOS) on the electrical characteristics of undoped (SIPSO)/p-Si, and n+-SIPOS/n-Si isotype junctions were investigated. The current-voltage characteristics of undoped SIPOS/p-Si heterojunctions exhibit a strong dependence on the oxygen content of the SIPOS film and depart from a hyperbolic sine behavior as the refractive index of the SIPOS increases.. The addition of nitrogen trifluoride decreases the current density of these undoped SIPOS/p-Si heterojunctions due presumably to the oxidation/hydrolysis of SiF species intoSiO2. The n+-SIPOS formed a rectifying isotype junction o n-Si. The forward current voltage characteristics exhibit two distinct …

Simplified Strength Prediction For Cold-Formed C- And Z-Shapes, Roger A. Laboube

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Although cold-formed steel C- and Z-shaped members possess a very favorable strength-to-weight ratio, are easily fabricated and erected, and offer a cost-effective structural design solution, they can be highly susceptible to local buckling. To adequately address the impact of the local buckling limit state, a complex, time-consuming design office effort may be required. Therefore, to facilitate the design of such shapes, a study was conducted that focused on developing relatively simple, easy-to-apply design guidelines. The design guidelines address the behavior of cold-formed steel C- and Z-shaped members when used as either a flexural member or a compression member. Both edge-stiffened …

Economic Impacts Of Noxious Facilities: Incorporating The Effects Of Risk Aversion, Leslie A. Nieves

RISK: Health, Safety & Environment (1990-2002)

The author suggests an integrative approach for projecting economic impacts of facilities that elicit public Risk aversion. She incorporates both economic stimulus effects and perception-based effects of facilities on the host area economy. Empirical findings are compared and an impact estimation framework is suggested for integrating psychometric and econometric techniques.

Temporal Development Of Electric Field Structures In Photoconductive Gaas Switches, K. H. Schoenbach, J. S. Kenney, F.E. Peterkin, R. J. Allen

Bioelectrics Publications

The temporal development of the electric field distribution in semi‐insulating GaAs photoconductive switches operated in the linear and lock‐on mode has been studied. The field structure was obtained by recording a change in the absorption pattern of the switch due to the Franz–Keldysh effect at a wavelength near the band edge of GaAs. In the linear mode, a high field layer develops at the cathode contact after laser activation. With increasing applied voltage, domainlike structures become visible in the anode region and the switch transits into the lock‐on state, a permanent filamentary electrical discharge. Calibration measurements show the field intensity …

Multiobjective Design Of Service Routes, J. R. Wright, Jin-Yuan Wang

JTRP Technical Reports

The purpose of this research has been the design of a computer-based decision support system for use in the design of service routes on the Indiana intrastate highway system. The following work has been completed for this purpose:

1) Acquisition of a 1:100,000 scale DLG data representation of the entire state transportation network.

2) Reclassification of those data with the aid of a computer-based interactive data filter and participation by DOT maintenance personnel from 6 districts.

3) Development of several route design algorithm components designed specifically for addressing the problem of routing snow and ice control vehicles for INDOT.

4) …

Test 1669: John Deere 7800 Powershift Diesel 19-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 …

Reversible Complexation Of O2 To (Meso-Tetraphenylporphyrinato)Cobalt(Ii) Plasma Polymer And Sublimed Films At Room Temperature, J. M. Skelly, Nicholas C. Morosoff, V. T. Stannett, A. L. Crumbliss

Chemical and Biochemical Engineering Faculty Research & Creative Works

No abstract provided.

Superheating Of Bi(0001), E. A. Murphy, H. E. Elsayed-Ali, J. W. Herman

Electrical & Computer Engineering Faculty Publications

Superheating of Bi(0001) by about 90 K above the bulk melting temperature is observed using time-resolved reflection high-energy electron diffraction with ∼200-ps time resolution. Larger temperature excursions above the bulk melting temperature result in melting accompanied by irreversible laser damage to the surface. The rhombohedral structure of Bi leads to very different behavior of material parameters upon melting as compared with fcc metals. Therefore, our observation of the superheating of Bi(0001), together with the previously observed superheating of Pb(111), suggests the generality of the superheating phenomenon.

Direct Measurements Of The Transport Of Nonequilibrium Electrons In Gold Films With Different Crystal Structures, T. Juhasz, H. E. Elsayed-Ali, G. O. Smith, C. Suárez, W. E. Bron

Electrical & Computer Engineering Faculty Publications

The transport of femtosecond-laser-excited nonequilibrium electrons across polycrystalline and single-crystalline gold films has been investigated through time-of-flight measurements. The thicknesses of the films range from 25 to 400 nm. Ballistic electrons as well as electrons interacting with other electrons and/or with the lattice have been observed. The ballistic component dominates the transport in the thinner films, whereas the interactive transport mechanism is dominant at the upper end of the thickness range. A slower effective velocity of the interactive component is observed in the polycrystalline samples, and is assumed to arise from the presence of grain boundaries. The reflection coefficient of …

Large Capacity Missile Carrier (Cmx), C. N. Calvano, J. M. Berner, J. M. Bradley, K. A. Tosiello, D. T. Hooker, C. F. Merrill

Engineering Management & Systems Engineering Faculty Publications

A systems engineering approach to the development of a radically different kind of surface combatant ship is presented, followed by a preliminary design of the ship shown by the analysis to be most effective. The requirement for the project was the development of a ship which would provide a major increase in the missile firepower of a battlegroup. The study conducts an analysis of four warfare scenarios and evaluates the effectiveness of replacing some Aegis ships with the missile carrier (CMX) and examines the relative utility of varying missile loads for the CMX. An alternative is chosen for further development …

Elastic Impact Of Beams On Gap-Spring Supports, Hany Aly Abdelhafiz

Archived Theses and Dissertations

No abstract provided.

Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez

Electrical & Computer Engineering Faculty Publications

The main objectives of our research are to present a self-contained overview of fuzzy sets and fuzzy logic, develop a methodology for control system design using fuzzy logic controllers, and to design and implement a fuzzy logic controller for a real system. We first present the fundamental concepts of fuzzy sets and fuzzy logic. Fuzzy sets and basic fuzzy operations are defined. In addition, for control systems, it is important to understand the concepts of linguistic values, term sets, fuzzy rule base, inference methods, and defuzzification methods. Second, we introduce a four-step fuzzy logic control system design procedure. The design …

A New Technique To Decompose Closely Spaced Interface And Bulk Trap States Using Temperature Dependent Pulse-Width Deep Level Transient Spectroscopy Method: An Application To Pt/Cds Photodetector, C. W. Wang, Cheng-Hsiao Wu, Jack L. Boone

Electrical and Computer Engineering Faculty Research & Creative Works

A novel method is presented here to experimentally decompose nonexponential capacitive transients into the appropriate components from the closely spaced deep trap states. Using temperature dependent pulse-width deep level transient spectroscopy (TDP-DLTS) technique, we show for the first time that two bulk trap states and one continuously distributed interface states in (Pt/CdS) photodiodes can be successfully separated. The basic principle is to set the applied pulse width to follow an averaged temperature-dependent capture time constant and divide the DLTS spectrum. In the example of Pt/CdS photodiodes, we show that all physical parameters including thermal activation energies, capture cross sections, and …