Engineering Commons^™

Acuta Enews July 1993, Vol. 22, No. 7

ACUTA Newsletters

In This Issue

Gain-share at Wake Forest

President's Message

North American Numbering Plan

Toll Fraud Checklist

Staff Report

Variable Structure End Point Control Of A Flexible Manipulator, Shailaja Chenumalla, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

We treat the question of control and stabilization of the elastic multibody system developed in the Phillips Laboratory, Edwards Air Force Base, California. The controlled output is judiciously chosen such that the zero dynamics are stable or almost stable. A variable structure control (VSC) law is derived for the end point trajectory control. Although, the VSC law accomplishes precise end point tracking, elastic modes are excited during the maneuver of the arm. A Linear stabilizer is designed for the final capture of the terminal state.

Single Scheduling Problem With Dependent Setup Cost, Mohamed Mahmoud Zaki

Archived Theses and Dissertations

No abstract provided.

Application Of Sequence Comparison Methods To Multisensor Data Fusion And Target Recognition, Edmund W. Libby

Theses and Dissertations

This research addresses methods for exploiting the joint likelihood of observed kinematic and nonkinematic (sensor signature) physical events to improve dynamic object and target recognition. A principal direction is the application of dynamic programming sequence comparison techniques to condition matching of object signatures to known models according to observed kinematics. A second direction is the application of kinematic/aspect-angle Kalman filter trackers to condition kinematic tracking according to observed signatures. These conditioning processes dramatically reduce ambiguity in object recognition, and can be used together or separately to allow computation of a posterior probabilities of object class membership using Bayesian methods. Proposals …

Three Points Of Great Height On Elliptic Curves, Andrew Bremner, Duncan A. Buell

Faculty Publications

We give three elliptic curves whose generators have great height, demonstrating along the way a moderately efficient method for finding such points.

Cal Poly Model Canal, John B. Parrish, Iii, Charles M. Burt

BioResource and Agricultural Engineering

The Cal Poly Model Canal, located at the Water Delivery Facility. Irrigation Training and Research Center, California Polytechnic State University, San Luis Obispo, Calif., was built to accommodate the study and promotion of automated downstream control. Being a large, fully functional scale model of a canal, it was used to collect data for use by the Irrigation Canal System Hydraulic Modeling Task Committee of the ASCE Irrigation and Drainage Division. The data was used by Task Committee members to help evaluate numerical models for simulation of unsteady free-surface flow. The Model Canal and the collected data are discussed. This paper …

Leukocyte Extravasation Into The Pancreatic Tissue In Transgenic Mice Expressing Interleukin 10 In The Islets Of Langerhans., Lise Wogensen, Xiaojian Huang, Nora Sarvetnick

Journal Articles: Regenerative Medicine

Transgenic expression of interleukin 10 (IL-10) in the islets of Langerhans leads to a pronounced pancreatic inflammation, without inflammation of the islets of Langerhans and without diabetes. A scattered infiltration of macrophages (M pi) precedes localized accumulations of CD4+ and CD8+ T lymphocytes, B lymphocytes, and M pi. This recruitment of inflammatory cells to the pancreas is somewhat surprising, since the biological activities of IL-10 in vitro indicate that IL-10 is a powerful immunosuppressive cytokine. Since endothelial cells play a major role in leukocyte extravasation, we examined if vascular changes and extralymphoid induction of peripheral and mucosal type vascular addressins …

Bs News

Building Services Engineering

No abstract provided.

Fiber Enhanced Viscoelastic Damping Polymers And Their Application To Passive Vibration Control, Houchun Xia

Mechanical & Aerospace Engineering Theses & Dissertations

A new composite damping material is investigated, which consists of a viscoelastic matrix and high elastic modulus fiber inclusions. This fiber enhanced viscoelastic damping polymer is intended to be applied to light-weight flexible structures as surface treatment for passive vibration control. A desirable packing geometry for the composite material is proposed, which is expected to produce maximum shear strain in the viscoelastic damping matrix. Subsequently, a micromechanical model is established in which the effect of fiber segment length and relative motion between neighboring fibers are taken into account. Based on this model, closed form expressions for the effective storage and …

A Computer-Based Strategy To Facilitate Organizational Learning Process, Charles B. Keating

Engineering Management & Systems Engineering Theses & Dissertations

This research investigated the development of Organizational Learning Process (OLP) through the application of a computer-based strategy in an organizational setting. OLP is developed from the organizational learning literature as an integration of similar concepts of organizational processes of inquiry essential to organizational learning. These concepts included: organizational dialectic (Argyris and Schon 1978), surfacing and testing mental models (Senge 1990a,1990b), and interpretation process (Daft and Weick 1984). A qualitative research methodology was developed within a participatory action research framework (Whyte 1989). A six phase research project, designed as a computer-based strategy to generate OLP, was applied in an organizational setting. …

Absorption Imaging Studies On Intrinsic Gaas, John Samuel Kenney

Electrical & Computer Engineering Theses & Dissertations

A diagnostic technique has been developed which allows recording of the temporal and spatial development of electric field structures in GaAs photoconductive switches. The optical method is based on the Franz-Keldysh effect. Measurements were performed with a Nd:YAG activation laser and a GaAs laser diode as the probe laser. At low applied voltages a 100 atm wide region of high electric field is seen at the cathode only. With increasing voltage strong domain like structures emerge at the anode also. A calibration measurement shows that the electric fields in these domains are well above 50 kV/cm. At a threshold voltage, …

Study Of Single-Fiber Fiber Optic Lever Microphone, Trung Duc Nguyen

Electrical & Computer Engineering Theses & Dissertations

Fiber optic sensors are widely used in today's technological applications, providing many advantages that conventional sensors lack. In particular, there is a demand in hypersonic applications to develop microphones to measure acoustic pressure that performs in high temperature and noisy surroundings. This thesis analyzes fiber optic lever microphones (FOLM), since they perform at high temperatures. An FOLM system is an intensity modulated sensor, which is simple to implement and is small in size. Two models of the FOLM have been fabricated and calibrated. The first model uses a seven-element fiber array while the second uses a single-fiber to transmit and …

Light Injection From An Active Cladding To The Core Of A Fiber Optic Fluorosensor, Alvin Leon Bryant

Electrical & Computer Engineering Theses & Dissertations

A fluorosensor works on the basis of light injection from the clad into the core of an optical fiber. The sensitivity of such a sensor depends on the efficiency of light injection. Conditions necessary for a high injection efficiency are experimentally determined. The refractive index difference between the core and the clad,ⁿcore ^-nclad, must be maximized to achieve a high injection efficiency. Since an air clad has the least refractive index, a bare core fiber will have a maximum efficiency. Standard optical fibers used for communication employ a minimum value for ⁿcore ^-nclad, in order …

Irrigation-Canal - Simulation Model Usage, Charles M. Burt, Gregory Gartrell

BioResource and Agricultural Engineering

Unsteady canal-simulation model usage requires serious investments of time and personnel. The reasons for deciding to invest in a model, as well as reasons not to invest, are discussed. For most cases, it is better to invest in the improvement of an existing model than the writing of a new model. Many excellent models are available, although very few can be considered user-friendly for the average design engineer. Unsteady flow-simulation models are not recommended for real-time control, but are key tools for the study of various control scenarios. Canal models can simulate an actual canal, but the user must input …

Optimizing Irrigation Management For Pollution Control And Sustainable Crop Yield, G. R. Musharrafieh, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

We developed a simulation-optimization model which maximizes crop yield while maintaining target salt concentration in the root zone, and/ or preventing salt from leaching to the groundwater. The model performs nonlinear optimization and simulation. Implicit finite difference forms of the nonlinear, transient, unsaturated water flow equation, and the convection-diffusion equation are embedded as constraints. Other constraints include nonlinear functions describing the hydraulic properties of the medium. The objectives of the management model is to develop irrigation strategies which prevent salt leaching to the groundwater when salty irrigation water is used. Five different irrigation strategies are developed for Huntington Research Farm, …

Exergetic Cost Analysis Of A Mechanical Exergy Recycle, Jim Mcgovern

Conference Papers

A mechanical plant that involves an exergy recycle is presented for analysis. It consists of gearboxes and a fluid coupling. There is one input of shaft power to the plant and there are three separate outputs of shaft power. An exergetic cost analysis approach is outlined and applied to the plant.

Study Of Algebraic Reynolds Stress Models For The Computation Of Secondary Motion In Channels, Tomas Chylek

Mechanical & Aerospace Engineering Theses & Dissertations

A three-dimensional computer code for solving Reynolds equations of turbulent flow at high Reynolds numbers in generalized curvilinear coordinates is used to study the engineering applications of several variants of linear and nonlinear second moment algebraic Reynolds stress models based on pressure-strain correlation of Launder, Recce and Rodi (1975) and Speziale, Sarkar and Gatski (1991). A new form of algebraic Reynolds stress equation in generalized curvilinear coordinates is derived based on simplification of Reynolds stress transport equations. Two implicit and two explicit implementations are explored in three different geometries of straight channel flows. The predictions of secondary motion driven by …

Comparison Of A Distributed Kalman Filter Versus A Centralized Kalman Filter With Fault Detection Considerations, Paul J. Lawrence Jr.

Theses and Dissertations

This project examined the results obtained by simulating an aircraft navigation system with a partial complement of a typical avionics sensor array. Two different techniques of estimation processes were utilized and compared: the conventional Kalman and the federated filter architectures. Areas of interest include error state estimation accuracy and overall performance, residual behavior under normal and induced sensor failure conditions, and potential for failure detection and isolation. Several simulations were accomplished for each filter design and the results were compared in order to verify the validity of the newly developed federated filter architecture. Comparison of the error state estimation accuracies …

Photoellipsometry Determination Of Surface Fermi Level In Gaas (100), Yi-Ming Xiong, Paul G. Snyder, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Photoellipsometry, a new contactless optical method, is presented, Related to photoreflectance, this method utilizes spectroscopic ellipsometry with the addition of a laser pump beam directed at nearly normal incidence onto the sample surface, where photoexcited electron-hole pairs modify the built-in electric field as a result of the photovoltaic effect. The field-induced changes in the real and imaginary parts of the complex pseudodielectric function can be directly measured, and analyzed in terns of the pump beam power density or the probe beam photon energy to determine parameters, such as surface Fermi level, built-in field strength, depletion depth, broadening, critical point energies, …

Construction Report Fhwa Special Project 202, Break And Seat Of Jointed Reinforced Concrete Pavement, R. Clark Graves, David L. Allen

Kentucky Transportation Center Research Report

This study is part of the FHWA sponsored Special Project 202, "Break and Seat of Jointed Reinforced Concrete Pavement" (SP-202). In addition to Kentucky, West Virginia, Ohio, and Louisiana are also participating in the project. The projects were constructed under the experimental design defined in the FHWA Document "Special Project 202 Technical Resource Forum", June 6 and 7, 1989. Breaking patterns of 6, 18, and 30 inches, along with a control section which was not broken were used in each of the participating states.

The only major problem which occurred during construction occurred in the inside lane of the 6-inch …

Boundary Layer Influences On The Subsonic Near-Wake Of A Family Of Three-Dimensional Bluff Bodies, Charles Willliam Alcorn

Mechanical & Aerospace Engineering Theses & Dissertations

A study is reported on subsonic bluff body near-wake flows. It has been determined that one family of bluff bodies, namely slanted-base ogive cylinders, can experience either a closed recirculating near-wake, or a longitudinal vortex near-wake depending on the base slant-angle and the Reynolds number. This suggests a dependence of near-wake parameters on the state of the boundary layer ahead of separation. This report addresses the influence of the boundary layer on the near-wake of slanted-base bluff bodies. Experiments were conducted in two facilities, the 6-inch Magnetic Suspension and Balance System (MSBS) at NASA Langley Research Center and the Old …

Boundary Value Problems In Rectilinearly Anisotropic Thermoelastic Solids, Gilbert Kerr

Mathematics & Statistics Theses & Dissertations

The boundary value problems which are considered are the type that arise due to the presence of a Griffith crack (or cracks) in an anisotropic thermoelastic solid. The thermoelastic field, in such materials, when the infinitesimal theory is employed, is governed by a set of elliptic partial differential equations. The general solution of these equations is expressed in terms of arbitrary analytic functions whose real parts, in turn, are expressed in terms of Fourier type integrals or Fourier series. Integral transform techniques are then used to determine the stress intensity factors (and other pertinent information) for various crack geometries. In …

Studies On Nonequilibrium Phenomena In Supersonic Chemically Reacting Flows, Rajnish Chandrasekhar

Mechanical & Aerospace Engineering Theses & Dissertations

This study deals with a systematic investigation of nonequilibrium processes in supersonic combustion. The two-dimensional, elliptic Navier-Stokes equations are used to investigate supersonic flows with nonequilibrium chemistry and thermodynamics, coupled with radiation, for hydrogen-air systems. The explicit, unsplit MacCormack finite-difference scheme is used to advance the governing equations in time, until convergence is achieved.

For a basic understanding of the flow physics, premixed flows undergoing finite rate chemical reactions are investigated. Results obtained for specific conditions indicate that the radiative interactions vary substantially, depending on reactions involving HO$\sb2$ and NO species, and that this can have a noticeable influence on …

Finite Element Analysis For An Involute Spur Gear Noise Excitation By Impact Effects, Wenbeen Li

Electronic Theses & Dissertations

The purpose of this study includes (1) to identify the relationship between the impact loads or backlash and the sound field pressure of impact direct noise of meshing gears, (2) to show that impact whether or not the impact direct noise contributes to the noise of overall gear system, and (3) to demonstrate how impact direct noise can be predicted. The method used to predict was finite element analysis and numerical solution. This research presents the analytical model of impact direct noise prediction for meshing gear teeth based on the data that the tooth vibration and surface are known by …

Three-Dimensional Transport Simulations Of The Dispersal Of Volcanic Aerosol From Mount Pinatubo, T. Duncan A. Fairlie

Mechanical & Aerospace Engineering Theses & Dissertations

A global finite-difference model that simulates the large-scale dynamics of the Earth's stratosphere and mesosphere is combined with a global spectral transport model to investigate aspects of the initial dispersal of the volcanic aerosol plume from the Mount Pinatubo eruption in 1991. Results of the modelling study are found to compare well with observations of the volcanic plume made from satellite instruments. Dynamical quantities, diagnosed from the simulated fields are used to provide insight into the evolution of the volcanic plume. Lagrangian trajectory analysis is used to help assess the performance of the Eulerian transport model and to highlight small-scale …

Development Of A Knowledge Based System For Wastewater Pipeline Failure Risk Assessment, Adam Mayanzani Ngaliga

Engineering Management & Systems Engineering Theses & Dissertations

The purpose of this thesis was to study and analyze the wastewater pipeline failure risk assessment process, and then design and develop an effective and efficient wastewater pipeline risk assessment tool for the Hampton Roads Sanitation District, in Virginia, U.S.A. A knowledge based system was developed using an expert system building shell (Xi-Plus).

The system design is based on the knowledge elicited from the experts and literature in sanitary pipeline failure risk evaluation. The knowledge base contains both heuristics and procedural rules. The system interprets the information provided by the user and reasons from that information to reach conclusions on …

A Multivariate Quality Control Approach For Automated Manufacturing Systems, Hisham Naim Ashur

Engineering Management & Systems Engineering Theses & Dissertations

In today's competitive manufacturing environment, effective and practical statistical quality control approaches are essential. A successful process control approach needs to provide on line real time monitoring of quality related characteristics.

No longer acceptable is an approach that analyzes quality related data only after the product is produced. A statistical process control approach that monitors the process during production and that reports trouble spots before bad products are made is necessary in an automated manufacturing environment.

An automated manufacturing environment is characterized by high volume production runs and short production cycles. Traditional statistical process control approaches are not capable of …

Optimum Design For Spring With Orthogonal Design Method, Han Fu - Jie

Tanzania Journal of Engineering and Technology (TJET)

Orthogonal design method is a sort of direct optimum method, by which the op- timal result may be obtained through simple computation and analysis. This method has gained increasingly extensive interest in scientific research, engineering design, end production management as well. The orthogonal table is the basic instrument for carrying out optimum design with orthogonal design method. It is a mathernatical table established On the basis Of the idea of isostatic distribution. As various levels may appear in any column, it makes a partial experiment contain levels of all factors furthermore. RII combina- tions of any two columns may appear …

Development And Testing Of Locally Produced Natural Rubber (Nr) And Pvc Blends, B Mutagahywa

Tanzania Journal of Engineering and Technology (TJET)

The mechanical properties of natural rubber - poly(vinyl chloride) blends have been studied. Tensile and tear strengths of the vulcanizates has been shown to increase with increasing proportions of PVC up to about 20 pphr. Abrasion loss and hardness decreases slightly with increasing concentration of PVC. Increased loading Of carbon black lowers the tensile and tear strength while increasing the abrasion loss and hardness values. This may be explained by the fact that PVC exists as a discontinuous rigid phase in the polymer compound. At normal loading of black (37 pphr) PVC improves processability and acts in the same way …

Antecedents, Moderators And Outcomes Of Organizational Commitment, Beatus Kundi

Tanzania Journal of Engineering and Technology (TJET)

This study examined: (I) the impact of the BtruCturaI of tenure, job integration and organizational support on organizational (2) the mediating roles of the cultural values for performance and collectivity, and the intra—individual factorg of organizational identification and the norm of reciprocity Ln the relationahip between the structural factore and organization coamitment; and, (3) the relationghip between organizational cormitment and the ouecome variablen Of abøeneeeigm, turnover and The Bhow that job and Of the for performance a gignificant facilitator of the effecte Of the etructuraL factors on commitment; and organization identification and the norm of rec are important linkø in …