Engineering Commons^™

University Nanosatellite Distributed Satellite Capabilities To Support Techsat 21, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A published article that included Professor Bob Twiggs titled "University Nanosatellite Distributed Satellite Capabilities to Support TechSat 21" from August 23, 1999.

Nutrient Balance On Nebraska Livestock Confinement Systems, Richard K. Koelsch, Gary Lesoing

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Managing the environmental risk associated with livestock production is a significant challenge. Nitrogen and phosphorus are commonly implicated as the sources of ground and surface water quality problems associated with livestock production. The degree of imbalance between these nutrient inputs and the managed nutrient outputs for a livestock operation defines the magnitude of potential environmental risk and provides insight as to the underlying causes of these challenges. A nitrogen and phosphorus balance was constructed for 33 Nebraska confinement livestock operations. Twenty-five and 17 of these operations experienced significant nitrogen and phosphorus imbalances, respectively (50% more nutrient inputs than outputs). Nutrient …

Apparatus And Method For Triboelectrostatic Separation, John M. Stencel, John L. Schaefer, Heng Ban, James K. Neathery

Center for Applied Energy Research Faculty Patents

A triboelectrostatic separation apparatus includes a separator with an inlet, a separation chamber, first and second electrodes, a variable voltage source for applying respective positive and negative voltage potentials to the electrodes, a pair of separated particle outlets and a curtain gas flow generation system. The curtain gas flow generation system includes a source of curtain gas at positive pressure, a metering valve for matching curtain gas flow velocity to particle flow velocity and flow straighteners for eliminating eddy currents. A method for separating electrostatically charged particles is also described.

Isotropic Dielectric Functions Of Highly Disordered AlXGa1-XInp (0≤X≤1) Lattice Matched To Gaas, Mathias Schubert, John A. Woollam, G. Leibiger, B. Rheinlander, I. Pietzonka, T. Sab, V. Gottschalch

Department of Electrical and Computer Engineering: Faculty Publications

Determination of the complex dielectric function and the critical-point energies of (Al_xGa_1-x)_0.51In_0.49P, over the full range of composition x and for photon energies E from 0.75 to 5 eV is reported from variable angle of incidence spectroscopic ellipsometry. Native-oxide effects on the (Al_xGa_1-x)_0.51In_0.49P optical functions are removed numerically. The highly disordered state of the metalorganic vapor-phase epitaxy grown samples is analyzed by transmission electron microscopy. Optical anisotropy investigations revealed that the order-induced optical birefringence is negligible throughout. The augmentation of A. D. …

Assessment Of Environmental Performance Of Rapid Prototyping And Rapid Tooling Processes, Yanchun Luo, Ming-Chuan Leu, Zhiming Ji

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A method for assessing the environmental performance of solid freeform fabrication (SFF) based rapid prototyping and rapid tooling processes is presented in this paper. In this method of assessment, each process is divided into a number of life stages. The environmental effect of each process stage is analyzed and evaluated based on an environmental index utilizing the Eco-indicators that were compiled by PreConsultants of the Netherlands. The effects of various life stages are then combined to obtain the environmental performance of a process. In the assessment of SFF processes, we consider the material use in the fabrication of a part, …

Rapid Tooling By Integrating Electroforming And Solid Freeform Fabrication Techniques, Bo Yang, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper describes a rapid tooling process that integrates solid freeform fabrication (SFF) with electroforming to produce metal tools including molds, dies, and electrical discharge machining (EDM) electrodes. Based on experimental data analysis, the geometry and material of the SFF part, the properties of the electroformed metal, and the process parameters are significant factors that cause inaccuracy in the manufactured tools. Thermomechanical modeling and numerical simulation is used to determine the geometry of the SFF part and the electroform thickness for minimizing the manufacturing time and cost while satisfying the tooling accuracy requirement.

An Experimental And Analytical Study Of Ice Part Fabrication With Rapid Freeze Prototyping, Wei Zhang, Ming-Chuan Leu, Guanghua Sui, Zhiming Ji

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Rapid Freeze Prototyping (RFP) is a new solid freeform fabrication process that builds an ice part by rapidly freezing water layer by layer. In this paper, we will present our recent progress in the development of this novel process. An experimental system has been built for conducting the research. It consists of an XY-table and Z-stroke driven by micro-stepping motors and a water dispensing and deposition subsystem which incorporates a solenoid valve and a syringe pump placed inside a freezer. Simple heat transfer analysis is made to help select proper values of process parameters and predict part building failures. Example …

Network Modeling Of The Convective Flow And Diffusion Of Molecules Adsorbing In Monoliths And In Porous Particles Packed In A Chromatographic Column, J. J. Meyers, Athanasios I. Liapis

Chemical and Biochemical Engineering Faculty Research & Creative Works

A cubic lattice network of interconnected pores was constructed to represent the porous structure existing in a monolith (continuous bed) or in a column packed with porous chromatographic particles. Expressions were also constructed and utilized to simulate, through the use of the pore network model, the intraparticle interstitial velocity and pore diffusivity of adsorbate molecules in porous chromatographic particles or in monoliths under retained and unretained conditions. The combined effects of steric hindrance at the entrance to the pores and frictional resistance within the pores, as well as the effects of pore size, pore connectivity, n(T), of the porous network, …

Polycrystalline Conducting Polymers And Precursors Thereof Having Adjustable Morphology And Physical Properties, Ravi F. Saraf

Department of Chemical and Biomolecular Engineering: Patents

Polycrystalline materials containing crystallies of precursors to electrically conductive polymers and electrically conductive polymers are described which have an adjustable high degree of crystallinity. The intersticial regions between the crystallites contains amorphous material containing precursors to electrically conductive polymers and/or electrically conductive polymers. The degree of crystallinity is achieved by preparing the materials under conditions which provide a high degree of mobility to the polymer molecules permitting them to associate with one another to form a crystalline state. This is preferable achieved by including additives, such as plasticizers and diluents, to the solution from which the polycrystalline material is formed. …

Electrodeposition Of Cerium-Based Coatings For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Xuan Lin, Eric L. Morris, Pu Yu, Srinivas Pravin Sitaram

Chemistry Faculty Research & Creative Works

A process for enhancing the corrosion resistance of an aluminum-containing component with a cerium based coating. An aluminum-containing cathode and an oxygen- evolving anode are immersed in an electrolyte comprising water, solvent, oxidizing agent and cerium ions. An electrical current is passed through the electrolyte by applying electrical current to deposit a cerium based coating onto the cathode. An electrolyte for use in depositing a cerium based coating. An electrodeposited cerium-based coating. An aluminum aircraft structural component having a cerium-based coating thereon.

Models For Magnetoresistance In Tunnel Junctions, Shi C. Zhang, P. M. Levy

Materials Science and Engineering Faculty Research & Creative Works

We show there are putative pitfalls when one predicts the magnetoresistance of magnetic tunnel junctions (JMR) based on different toy models. Amongst them are the sensitivity of the MR to the details of the profile of the potential barrier between the metallic electrodes and the insulating barrier, and the common assumption of only one band of electrons. We indicate the ingredients that are necessary to obtain a more complete description of the JMR of magnetic tunnel junctions.

Ccfss Technical Bulletin August 1999, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Technical Bulletins (1993 - 2020)

No abstract provided.

Acuta Enews August 1999, Vol. 28, No. 8

ACUTA Newsletters

In This Issue

Annual Conference Highlights

ACUTA EVENTS

ACUTA Upgrades Web Site

DC Update

Indiana University Hosts Local Events

Board Report

Overheard on the Listserve

Welcome New Members

Positions Available

Chu Spaces - A New Approach To Describing Uncertainty In Systems, Vladik Kreinovich, Guoqing Liu, Hung T. Nguyen

Departmental Technical Reports (CS)

This paper proposes the use of a specific type of categories for modeling and fusing information in complex systems in which uncertainty of various types need to be taken into account.

Neural Network Approach To Speech Pathology, Antonio P. Salvatore, Nicole A. Thorne, Charlotte M. Gross

Departmental Technical Reports (CS)

A speech problem can be caused by different reasons, from psychological to organic. The existing diagnostic of speech pathologies relies on skilled doctors who can often diagnose by simply listening to the patient. We show that neural networks can simulate this ability and thus provide an automated (preliminary) diagnosis.

Kolmogorov Complexity-Based Ideas For Locating Text In Web Images, Martin Schmidt, Vladik Kreinovich, Luc Longpre

Departmental Technical Reports (CS)

The gaining popularity of the World Wide Web increases security risks. Search tools monitor plain text in web pages, but search for text in graphical images is still difficult. For this search, we use the fact that the compressed images with text have different size than images without text.

Evaluation Of Caltrans District 10 Automated Warning System, Year Two Progress Report, Art Maccarley

Electrical Engineering

District 10 of the California Department of Transportation (Caltrans) encompasses an area of seasonal fog and dust-related visibility problems that have been the cause of numerous multi-car traffic collisions, many fatal. In 1990, motivated by the expansion of State Route 120 (SR 120) connecting Interstate Highway 5 (I-5) and State Route 99 (SR 99), Caltrans proposed a sophisticated multi-sensor automated warning system as a means for reducing incidents in this high-traffic area. This proposal, and the significant development effort that followed, culminated in the implementation of Phase 1 of the Caltrans Automated Warning System, or “CAWS”, which entered service in …

Santa Clara Magazine, Volume 41 Number 2, August 1999, Santa Clara University

Santa Clara Magazine

8 - APOCALYPSE PAST: Y1K By Thomas Turley. The year 2000 is upon us. But what about Y1K? History Professor Thomas Turley takes an historical look at the millennial fever of a thousand years ago.

12 - THE FUTURE IS MATH By Susan Vogel. Math Lecturer David Sul is on a mission: to get more Hispanics and African-Americans into Calculus and onto college through SCU's Calculus 100 program.

16 - The Class of 1999 Moves On By Sug Ramire '98. Optimism is the byword for the last graduating class of the millennium. Six 1999ers share their impressions, hopes, and fears …

Theoretical Explanation For The Empirical Probability Of Detection (Pod) Curve: A Neural Network-Motivated Approach, Yohans Mendoza, Roberto Osegueda

Departmental Technical Reports (CS)

For non-destructive testing of aerospace structures, it is extremely important to know how the probability of detecting a fault depends on its size. Recently, an empirical formula has been found which described this dependence. In this paper, we provide the theoretical justification for this formula by using methods motivated by the neural network approach.

Fuzzy Logic In Non-Destructive Testing Of Aerospace Structures, Murali Krishna, Vladik Kreinovich, Roberto Osegueda

Departmental Technical Reports (CS)

In nondestructive testing, to locate the faults, we send an ultrasonic signal and measure the resulting vibration at different points. To describe and combine the uncertainty corresponding to different measurements and fuzzy estimates, we used fuzzy logic. As a result, we get reasonably simple computational models which lead to as good fault detection as the known more complicated models.

41st Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 41st annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 1-5, 1999.

Strength And Weaknesses Of Npv Analysis And Its Application To Aircraft Value Modeling, Sebastian Lourier

Master's Theses - Daytona Beach

The purpose of this study is to analyze the Net Present Value (NPV) technique as a mean to forecast aircraft values and the analysis of aircraft value forecasting accuracy. The main part of the examination is the evaluation of the actual quality of aircraft appraisals. The appraisal evaluation is based on historical forecast accuracy determinations and on a comparison of 1998 aircraft value forecasts. The discussion of a survey conducted by the author in 1998, will reveal the disunity among the appraisers. The survey data was provided generously by the appraisers most recognized in the industry. A sensitivity analysis exhibits …

Conform- A Computerized Job-Built Concrete Construction Formwork Design, Kajpong Pongponrat

Masters Theses

Economy in formwork design depends partly on the ingenuity and experiences of the form designer, whether a contractor or an engineer. The cost of formwork is significant, generally amounting to anywhere from 40% to 60% of the cost of a concrete structure. Judgment with respect to the development of a forming system could both expedite a project and reduce costs. The present paper addresses the development of CONFORM - an interactive menu driven PC based job-built concrete formwork design. The system is developed using Microsoft Visual Basic 6, Access 97 database, and Word 97, where a perfect integration of these …

Cell/Dendrite Distribution In Directionally Solidified Hypoeutectic Pb-Sb Alloys, S. P. O'Dell, G. L. Ding, Surendra N. Tewari

Chemical & Biomedical Engineering Faculty Publications

The alloys Pb-2.2 wt pet Sb and Pb-5.8 wt pet Sb were directionally solidified with three different thermal gradients of 40, 86, and 140 K cm(-1) at growth rates ranging from 0.6 to 30 mu m s(-1). A Gaussian peak amplitude analysis of the cell/dendrite spacing distribution shows a distinct peak corresponding to the nearest neighbors. The peaks corresponding to the second and the third nearest neighbor spacings are also brought out by this technique. The ratios of the second to the first nearest neighbor spacings and that of the third to the first neighbor spacings are 1.85 +/-: 0.11 …

Macrosegregation Caused By Thermosolutal Convection During Directional Solidification Of Pb-Sb Alloys, S. N. Ojha, G. L. Ding, Y. Lu, J. Reye, Surendra N. Tewari

Chemical & Biomedical Engineering Faculty Publications

Pb-2.2 and 5.8 wt pet Sb alloys were directionally solidified with a positive thermal gradient of 140 K cm(-1) at growth speeds ranging from 0.8 to 30 mu m s(-1), and then quenched to retain the mushy-zone morphology. Chemical analysis along the length of the directionally solidified portion and in the quenched melt ahead of the dendritic array showed extensive longitudinal macrosegregation, Cellular morphologies growing at smaller growth speeds are associated with larger amounts of macrosegregation as compared with the dendrites growing at higher growth speeds. Convection is caused, mainly, by the density inversion in the overlying melt ahead of …

Cost Effective Concrete Pavement Cross Sections - Interim Report, James Crovetti

Transportation Reports with the Wisconsin Department of Transportation

The present pavement selection policy of the Wisconsin Department of Transportation (WisDOT) limits the design alternatives for Portland Cement Concrete (PCC) pavements and inhibits the designer's ability to select cross-sections deviating from uniform slab thicknesses with doweled transverse joints. Currently, uniform slab thicknesses and conventional joint load transfer devices are incorporated into the design based on the heavy truck traffic in the outer lane. While this strategy provides for adequate pavement structure in this truck lane to limit faulting and slab cracking to tolerable levels, there is a potential for over-design in other traffic lanes which receive significantly lower Equivalent …

Nonlinear Robust Missile Autopilot Design Using Successive Galerkin Approximation, Timothy Mclain, Randal W. Beard

Faculty Publications

The application of a new nonlinear robust control strategy to the design of missile autopilots is presented. The control approach described and demonstrated here is based upon the numerical solution of the Hamilton-Jacobi-Isaacs equation by Successive Galerkin Approximation. Using this approach, feedback controllers are computed by an iterative application of a numerical Galerkin-type PDE solver. Application of this approach to the design of a pitch-axis autopilot for a missile having uncertain pitch moment and lift force is described.

Elastic Wave Propagation And Scattering In Heterogeneous, Anisotropic Media: Textured Polycrystalline Materials, Joseph A. Turner

Nebraska Center for Materials and Nanoscience: Faculty Publications

The propagation of elastic waves through heterogeneous, anisotropic media is considered. Appropriate ensemble averaging of the elastic wave equation leads to the Dyson equation which governs the mean response of the field. The Dyson equation is given here in terms of anisotropic elastic Green’s dyadics for the medium with and without heterogeneities. The solution of the Dyson equation for the mean response is given for heterogeneities that are weak. The formalism is further specified for the case of equiaxed cubic polycrystalline metals with a single aligned axis. The Green’s dyadics in this case are those for a transversely isotropic medium. …

Signal Induced Emi In Fibre Channel Cable-Connector Assemblies, Minjia Xu, S. Radu, James L. Knighten, James L. Drewniak, Todd H. Hubing, L. O. Hoeft, J. T. Dibene Ii

Electrical and Computer Engineering Faculty Research & Creative Works

The EMI performance of cable-connector assemblies designed for FC-0 transmission has been studied. Two types of cable and two connector styles were evaluated. Experimental results show that the dominant radiation mechanism for short cable lengths is the common-mode current caused by source and PCB skew that leaks to the exterior of the shield via the transfer impedance of the connector. However, the cable imbalance becomes a more significant source of common-mode current than the source skew when the cable assembly is tens of meters long.

Emi Associated With Inter-Board Connection For Module-On-Backplane And Stacked-Card Configurations, Xiaoning Ye, Jim Nadolny, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

EMI associated with inter-board connection was studied through common-mode current measurements and FDTD modeling for stacked-card and module-on-backplane configurations. Three types of connections were investigated experimentally including an open pin field connection, an "ideal" semi-rigid coaxial cable connection, and a production connector. Both microstrip and stripline signal routing on the PCB were investigated. The results indicated signal routing on the PCBs or the inter-board connection can dominate the EMI process. Several cases of connector geometries were studied using FDTD modeling and good agreement was achieved between the measured and FDTD results.