Engineering Commons^™

Permeability Of Microporous Carbon Preforms, S. K. Datta, N. Simhai, Surendra N. Tewari, Jorge E. Gatica, M. Singh

Chemical & Biomedical Engineering Faculty Publications

The permeability of microporous amorphous carbon preforms with varying pore size and pore distributions has been experimentally examined. The porous structures have been characterized by mercury porosimetry and by quantitative metallography of pressure-infiltration-cast metal matrix composites based on the carbon preforms. The permeability shows a linear correlation with the fraction porosity and the square of the pore diameter.

The Preliminary Design Of A Standardized Spacecraft Bus For Small Tactical Satellites, Gerald Ashby, Darren Buck, Robert Carneal Iv, Tansel Cokuysal, Ahmet Donmez, James From, Todd Krueger, Brian Robinson

Theses and Dissertations

Current satellite design philosophies concentrate on optimizing and tailoring a particular satellite bus to a specific payload or mission. Today's satellites take a long time to build, checkout, and launch. An alternate approach shifts the design paradigm to one that focuses on access to space, enabling tactical deployment on demand and the capability to put current payload technology into orbit, versus several years by today's standards, by which time the technology is already obsolete. This design study applied systems engineering methods to create a satellite bus architecture that can accommodate a range of remote sensing mission modules. System-level and subsystem-level …

Development Of Site Characterization Simulator Specifications, Jeffrey L. Heiderscheidt

Theses and Dissertations

The purpose of this study was to develop a tool for evaluating data quality when characterizing a potentially contaminated groundwater aquifer, and to provide a basis for developing a simulator to allow environmental managers and engineers to practice and learn about the site characterization process. Specifically, this study characterized the uncertainty, estimation block size, and cost for the various methods of determining the value of each geological, hydrological, and contaminant parameter necessary to characterize a site. Research entailed identifying site characterization objectives and identifying parameters necessary to obtain those objectives. Methods of estimating each parameter were identified, then research was …

Distributed Activation Energy Model Of Heterogeneous Coal Ignition, John C. Chen

Mechanical Engineering

We present a model that simulates the conventional tube-furnace experiment used for ignition studies. The Distributed Activation Energy Model of Ignition accounts for particle-to-particle variations in reactivity by having a single preexponential factor and a Gaussian distribution of activation energies among the particles. The results show that the model captures the key experimental observations, namely, the linear increase in ignition frequency with increasing gas temperature and the variation of the slope of the ignition frequency with oxygen concentration. The article also shows that adjustments to the model parameters permit a good fit with experimental data.

Multimedia Applications Require Adaptive Cpu Scheduling, Veronica Baiceanu, Crispin Cowan, Dylan Mcnamee, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

CPU scheduling and admission testing for multimedia applications have been extensively studied, and various solutions have been proposed using assorted simplifying assumptions. However, we believe that the complexity and dynamic behavior of multimedia applications and systems make static solutions hard to apply in real-world situations. We are analyzing the difficulties that arise when applying the rate-monotonic (RM) scheduling algorithm and the corresponding admission tests for CPU management, in the context of real multimedia applications running on real systems. RM requires statically predictable, periodic workloads, and while multimedia applications appear to be periodic, in practice they exhibit numerous variabilities in workload. …

Generalized Beam Matrices. Iii. Application To Diffraction Analysis, Lee W. Casperson, Anthony A. Tovar

Electrical and Computer Engineering Faculty Publications and Presentations

In analogy with Huygen’s wavelets a new method based on Gaussian beamlets is used to develop a conventional diffraction integral formalism for paraxial optical systems representable by complex 2×2 ABCD Gaussian beam matrices. This method, along with a new phase parameter transformation, is then used to produce a new diffraction integral for studying the propagation of light beams with arbitrary spatial profiles through much more general misaligned complex optical systems representable by 3×3 ABCDGH beam matrices.

Mechanisms Of Cytokine-Mediated Localized Immunoprotection., Nora Sarvetnick

Journal Articles: Regenerative Medicine

No abstract provided.

Row Crop Drip Irrigation On Peppers Study, Charles M. Burt, Stuart Styles

BioResource and Agricultural Engineering

High Rise Farms, located just north of Morgan Hill installed a new buried row crop drip irrigation system in 1993. The amount of the CEC loan was $42,700.

The installation of the drip irrigation system on the Peppers did provide significant improvements in the amount of water use, energy required and yield increases especially in the first year of operation (1993) and the third year of operation (1995). The second year of the project (1994) did not have yield increases. The primary lessons learned from this project included:

• The yield differential between drip and the furrow irrigation methods was attributed …

A Real-Time Self-Tuning Web Tension Regulation Scheme, Brian T. Boulter, Zhiqiang Gao

Electrical and Computer Engineering Faculty Publications

A self-tuning control scheme is proposed for tension regulation in a web transport system. A computationally efficient self-tuning method is first described. The frequency domain model of the plant is then described. Simulations of the on-line tuning are presented. The paper closes with a discussion of cognizant real-time implementation issues.

On Hack's Law, Riccardo Rigon, Ignacio Rodriguez-Iturbe, Amos Maritan, Achille Giacometti, David G. Tarboton, Andrea Rinaldo

Civil and Environmental Engineering Faculty Publications

Hack's law is reviewed, emphasizing its implications for the elongation of river basins as well as its connections with their fractal characteristics. The relation between Hack's law and the internal structure of river basins is investigated experimentally through digital elevation models. It is found that Hack's exponent, elongation, and some relevant fractal characters are closely related. The self-affine character of basin boundaries is shown to be connected to the power law decay of the probability of total contributing areas at any link and to Hack's law. An explanation for Hack's law is derived from scaling arguments. From the results we …

Analysis Of Small Airports Within A One Hundred And Twenty Mile Radius Of Medium And/Or Large Airports, Cheryl Mitchell Cunningham

Master's Theses - Daytona Beach

The purpose of this research is to investigate how income, population age, scheduled air carrier services, and distance between competing airports impact annual scheduled passenger enplanements for airports in smaller communities. Small airports located within a 120 miles radius of larger sized (medium or large) airports are considered to be within the "shadow" of larger airports with which they must compete for passenger enplanements.

Two methods were employed to evaluate shadow airports within a 120 mile radius of larger airports. First, an historical view, analyzing each of the airports with regard to schedule passenger enplanements, median disposable incomes, median ages, …

Investigation Of Fundamental Emi Source Mechanisms Driving Common-Mode Radiation From Printed Circuit Boards With Attached Cables, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Fei Sha, Michael J. Wilhelm

Electrical and Computer Engineering Faculty Research & Creative Works

Fundamental EMI source mechanisms leading to common-mode radiation from printed circuit boards with attached cables are presented in this paper. Two primary EMI source mechanisms have been identified: one associated with a differential-mode voltage and another associated with a differential-mode current, both of which result in a common-mode current on an attached cable. These mechanisms can be used to relate printed circuit layout geometries to EMI sources. The two mechanisms are demonstrated through numerical and experimental results, and an example from a production printed-circuit design is presented.

Use Of Audible Pedestrian Signals, Kenneth R. Agent

Kentucky Transportation Center Research Report

Audible pedestrian signals are a device used to provide additional traffic control at signalized intersections to aid visually impaired pedestrians. An objective of this study was to determine the status of the use of this device and investigate possible guidelines for possible future installations of audible pedestrian signals in Kentucky. Another specific objective was to investigate the need for such signals at a number of intersections at the University of Kentucky.

The study showed that audible pedestrian signals can be used to supplement the standard pedestrian signals. However, their use must be limited to intersections with a demonstrated need and …

Characterization Of Sr‐Doped Lamno3 And Lacoo3 As Cathode Materials For A Doped Lagao3 Ceramic Fuel Cell, Kevin Huang, Man Feng, John B. Goodenough, Michael Schmerling

Faculty Publications

Energy dispersive spectrometry line scan and ac impedance spectroscopy were used in this study to investigate the chemical reactions between two cathode materials, La_0.84Sr_0.16MnO₃ (LSM), La_0.5Sr_0.5CoO_3-δ (LSC), and the electrolyte La_0.9Sr_0.1Ga_0.8Mg_0.2O_2.85 (LSGM). Significant interdiffusions of Co into LSGM and Ga into LSC were found at an LSC/LSGM interface even at relatively low fabrication temperatures. In contrast, only small interdiffusions of Mn into LSGM and Ga into LSM were detected at the LSM/LSGM interface even though it was fired at 1470°C. The …

Membrane Analogy For Saint-Venant Torsion: New Results, Stephen M. Heinrich

Civil and Environmental Engineering Faculty Research and Publications

The Saint-Venant torsion problem for a twisted shaft may be formulated in terms of the Prandtl stress function (PSF) or the conjugate warping function (CWF), each of which may be interpreted as the transverse deflection of a thin membrane via the well-known membrane (soap-film) analogies. The deflection of the PSF membrane is associated with a uniform transverse pressure loading, whereas the CWF membrane is nonpressurized—its deformation is due solely to imposed deflections along its edge. The utility of the PSF analogy stems from the simple relationships that exist between the geometry of the deformed membrane (slope, enclosed volume) and the …

Fracture Mechanics Of High Strength Concrete Members, Rajendra K. Navalurkar

Dissertations

This study investigates the behavior of High Strength Concrete (HSC) under uniaxial state of stresses. Emphasis is placed on experimental evaluation of important mechanical and fracture properties. Owing to high brittleness of HSC, experimental results especially on tensile behavior have been largely limited and scarce. In this research, direct uniaxial tension tests are employed for determination of the post-peak tensile softening characteristics of HSC. The softening characteristics of high strength concrete is found to be considerably different than that of normal strength concrete (NSC). Fracture energies evaluated form the descending branch of the stress softening reveal significant drop in the …

A Controlled Release Technique Using Microporous Membranes, Stephanie Farrell

Dissertations

A novel controlled release device based on aqueous-organic partitioning is described. The device comprises a reservoir, bounded by a microporous or porous membrane in the form of a hollow fiber or flat film. The reservoir liquid phase and the pore liquid phase are immiscible. The agent partitions between the phases at the aqueous-organic interface of the reservoir and the pore mouth, and then diffuses through the membrane pore liquid into a surrounding aqueous solution. The partition coefficient significantly influences the rate of release of the agent by reducing the driving force for diffusion across the fluid-filled membrane pore. The performance …

Vapor-Liquid Phase Equilibria Of Nonideal Fluids With A Ge-Eos Model, Socrates Ioannidis

Dissertations

This study dealt with the prediction and correlation of vapor-liquid equilibria behavior of nonideal fluids. The thermodynamic formalism of the G^E-EoS models, which combines the two traditional methods γ-Φ and Φ-Φ used so far for low and high pressure phase equilibria correlations respectively, has been combined with the 1FG^E model, based on one-fluid theory, to produce a more consistent approach to the phase equilibrium problem.

In the first part of our study we examine the predictive abilities of our model for vapor-liquid equilibria of highly nonideal fluids. The results establish the fact that the Huron-Vidal mixing rule …

Local Stresses On Lateral Pipe-Nozzle With 45 Degree Angle Intersection, James Jin Xu

Dissertations

This dissertation presents a comprehensive study of local stresses, due to internal pressure around a pipe-nozzle with 45 degree angle intersection_ The resulting circumferential and longitudinal stresses on the pipe around the pipe-nozzle region are normalized as local stress factors and plotted as function of beta, β, (the radius of the nozzle/the radius of the pipe) and gamma, y, (the radius of the pipe/the thickness of the pipe) through the finite element method. The range of beta, [3, is from 0.1, to 1.0, and gamma, y, from 10 to 300. Comprehensive studies were made for the boundary parameters, such as …

Motion Estimation And Video Coding, Xiaochun Xia

Dissertations

Over the last ten years. research on the analysis of visual motion has come to play a key role in the fields of data compression for visual communication as well as computer vision. Enormous efforts have been made on the design of various motion estimation algorithms.

One of the fundamental tasks in motion estimation is the accurate measurement of 2-D dense motion fields. For this purpose. we devise and present in this dissertation a multiattribute feedback computational framework. In this framework for each pixel in an image. instead of a single image intensity. multiple image attributes are computed as conservation …

Pulsed Transient Tissue Conductivity Measurement, Robert B. Szlavik, Hubert De Bruin

Biomedical Engineering

The authors present an alternative technique for obtaining tissue conductivity as a function of frequency. Pulsed transient tissue impedance measurement differs significantly from other commonly used swept frequency techniques in that the conductivity of a tissue sample can be obtained from a voltage transient response to a current pulse. By obtaining the conductivity across a band of frequencies from a transient measurement, the necessity for direct conductivity measurements at each frequency point is eliminated. Calibration and verification of the technique was carried out by measuring the impedance magnitude and phase of simple RC circuit combinations. The authors present conductivity measurements …

Scheduling And Discrete Event Control Of Flexible Manufacturing Systems Based On Petri Nets, Huanxin Henry Xiong

Dissertations

A flexible manufacturing system (FMS) is a computerized production system that can simultaneously manufacture multiple types of products using various resources such as robots and multi-purpose machines. The central problems associated with design of flexible manufacturing systems are related to process planning, scheduling, coordination control, and monitoring. Many methods exist for scheduling and control of flexible manufacturing systems, although very few methods have addressed the complexity of whole FMS operations. This thesis presents a Petri net based method for deadlock-free scheduling and discrete event control of flexible manufacturing systems. A significant advantage of Petri net based methods is their powerful …

Novel High-Speed Architecture For Machine Vision Applications, Bassam S. Farroha, Raghvendra G. Deshmukh

Electrical Engineering and Computer Science Faculty Publications

This paper focuses on producing a state-of-the-art technique for designing an image recognition system for machine vision applications. The motivation behind the new system design is to provide a unique methodology, using strategic design techniques, to implement a system that addresses real-world image recognition applications. The introduction of application-specific, massively parallel array of processors, where low-level processing is accomplished on reconfigurable hardware structures, highlights the scheme. The system was built and simulated on a VLSI chip and results were verified using Electric Rules Check and Harris Timing Analysis examination tools. The system is composed of there functional layers and a …

Relationship Between Precipitation, Surface Runoff, And Shallow Water-Table, Manoj Patel

Theses

In this study, a model was developed to describe the relationship between precipitation, surface runoff, and shallow groundwater table in a watershed that is subjected to groundwater extraction and urbanization. Regression analysis of fourteen years (1976-1989) of time series data for precipitation, stream discharge, ground water elevation, and groundwater extraction yielded good correlation between these parameters.

Analysis of the data associated with groundwater recharge and discharge events that occurred in the watershed from 1976 to 1989 yielded a high correlation between the above cited parameters. Regression analysis utilized to predict monthly variations in groundwater elevations showed a fair correlation between …

Residual Stress Analysis Of Sputtered Tantalum Silicide Thin Film, Young Joo Song

Theses

The influence of different argon pressures on the residual stress, microstructure, and resisitivity of sputtered tantalum silicide thin films has been investigated. TaSi₂ films were deposited onto Si wafers by dc magnetron sputtering. The deposition temperature was assumed to be 300°C. The thickness was about 0.5 μm. The residual stresses in the films deposited at different argon pressures were determined by curvature measurement method. The compressive intrinsic stress of 1033.4MPa was measured at P_Ar = 0.5 mTorr. The intrinsic stress in the films seemed to change from compression to tension as P_Ar increased above 8mTorr. A maximum …

Low Pressure Chemical Vapor Deposition Of Silicon Dioxide And Phosphosilicate Glass Thin Films, Vijayalakshmi Venkatesan

Theses

Silicon dioxide thin films were synthesized on silicon and quartz wafers using Ditertiarybutylsilane(DTBS) and oxygen as precursors. Trimethylphosphite (TMP) was injected to obtain phosphosilicate glass. The films were processed at different temperatures between 700°C and 850°C at a constant pressure, and at different flow ratios of the precursors. The films deposited were uniform, amorphous and the composition of the films varied with deposition temperature and precursor flow ratios. The deposition rate increased with increasing temperature and with increasing TMP flow rate. The stresses were very low tensile in the case of undoped silicon dioxide film and tended towards being less …

Real-Time Implementation Of An Adaptive Control System For A 3-Zone Rapid Thermal Processing Station, David Hur

Theses

In this thesis, the implementation details of a real time adaptive control system for a TI 3-zone RTP station, as well as the simulation and the experimental results are presented. Extensive simulation of the system is performed in order to ensure proper operation of the system. The experimental results are used to verify proper operation of the closed loop control system. Initial experiments were conducted using two thermocouples. Further experiments were conducted using one thermocouple for the purpose of testing the performance of the system using Extended Kalman Filter as the state estimator.

The implementation of the control system is …

Removal Of Volatile Organic Compounds From Contaminated Groundwater By Pervaporation, Sukla Chandra

Theses

Effective removal of non-aqueous phase liquid pools in groundwater and volatile organic compounds (VOCs) from contaminated soils can be achieved by surfactant flushing. This surfactant-rich ground water contains VOCs like trichloroethylene (TCE), dichloroethylene (DCE), etc. Membrane pervaporation technique is employed here to remove TCE from these micellar systems where a very high percentage of the VOC is trapped inside the micellar core. The micellar solution flows through the bore of microporous hydrophobic hollow fibers wherein the micelles break down and release the surfactants and the TCE. The TCE is then removed through the pores and a nonporous thin silicone skin …

Biodegradation And Landfill Settlement, Shailesh Pisolkar

Theses

The most widely used method for the final disposal of solid waste is landfilling, which is also economical and simpler than most other disposal systems. Long term settlement in a landfill occurs mainly due to biodegradation of the refuse which is a very slow microbiological process. However, if the rate of biodegradation is enhanced, it may be possible to achieve early stabilization, faster settlement, consequently more capacity of the landfill to handle waste.

The objective of this research is to study the effects of enhanced biodegradation on settlement and to compare these results to other models used for predicting landfill …

Solids Suspension And Power Dissipation In Stirred Tanks Agitated By An Impeller Near The Tank Bottom, Ernesto Uehara-Nagamine

Theses

In this work, the effect of very small impeller clearances off the tank bottom, C, on complete solid off-bottom suspension, Njs, was investigated. Four types of impellers were used six-blade flat-disk turbine, six-blade flat-blade turbine, six-blade flat (45 degreees) pitched-blade turbine, and the high efficiency impeller Chemineer HE-3. The effects of the impeller diameter, D, tank diameter, T, and solids loading, X, were quantified. The presence of two impellers was analyzed using impellers of the same type and size.

Typically, Njs and the power consumption were found to decrease with the impeller clearance. However, for lower C/T values, a slight …