Engineering Commons^™

Influence Of Prior Deformation On Structure And Properties Of Heat Treated Aluminum Casting Alloy, Chungwei Hsia

Masters Theses

"A1 356 alloy is extensively used for a wide variety of casting applications. The structure is composed of primary dendrites and eutectic silicon formed during the eutectic reaction. It has long been recognized that the shape of the eutectic silicon significantly affects the ductility of the alloy. Traditionally, the morphology of the silicon is changed by certain chemical and/or thermal processes to improve the ductility. Mechanically deforming the castings to "modify" the shape of silicon has been shown by this research to be an effective alternative method to improve the spheroidization rate of eutectic silicon during heat treatment. The best …

An Optically Controlled Closing And Opening Semiconductor Switch, K. H. Schoenbach, V. K. Lakdawala, R. Germer, S. T. Ko

Electrical & Computer Engineering Faculty Publications

A concept for a bulk semiconductor switch is presented, where the conductivity is increased and reduced, respectively, through illumination with light of different wavelengths. The increase in conductivity is accomplished by electron ionization from deep centers and generation of bound holes. The reduction of conductivity is obtained by hole ionization from the excited centers and subsequent recombination of free electrons and holes. The transient behavior of electron and hole density in a high power semiconductor (GaAs:Cu) switch is computed by means of a rate equation model. Changes in conductivity by five orders of magnitude can be obtained.

Raman Scattering Characterization Of The Microscopic Structure Of Semi-Insulating Polycrystalline Si Thin Films, D.J. Olego, H. Baumgart

Electrical & Computer Engineering Faculty Publications

Raman scattering experiments were carried out to study the microscopic structure of semi-insulating polycrystalline Si (SIPOS) thin films prepared by low-pressure chemical vapor deposition. The samples contain 18, 25, and 30 at. % of oxygen and after growth they were annealed at 900 and 1000°C for 30 min. The Raman spectra show in the vibrational region of the optical frequencies of Si two bands, which arise from scattering in crystalline grains and disordered forms of Si. The behavior of these bands as a function of oxygen content and annealing temperatures was established in detail. The crystallinelike band peaks below the …

Strains In Si-Onsio2 Structures Formed By Oxygen Implantation: Raman Scattering Characterization, D.J. Olego, H. Baumgart, G.K. Celler

Electrical & Computer Engineering Faculty Publications

Low-temperature Raman scattering measurements were carried out to characterize Si-on-SiO₂ structures formed by oxygen implantation and subsequent furnace or lamp annealing. The experiments were conducted with 413.1 nm laser light to probe only the thin Si layers at the top of the structures. The Raman spectra of the furnace-annealed samples are red shifted and broadened when compared with a virgin Si surface. The shifts and broadenings decrease with increasing annealing temperatures but they are still present in samples annealed above 1250°C for 3 h. No shifts or broadenings affect the Raman peaks of the layers, which were lamp annealed …

A Simple Solid-Phase Electrophoretic Procedure For The Separation Of Plasmid Dna, Linda Ann Simurra

Biological Sciences Theses & Dissertations

A method was developed for extraction of plasmid DNA from bacterial cells embedded in agarose blocks. Cell - containing blocks were treated with various lysing reagents and inserted into the wells of an agarose gel. Upon electrophoresis the plasmid DNA migrated out of the embedding block and into the gel leaving intact chromosomal DNA in the well. This method was tested with various organisms and found to be effective for plasmid isolation. In comparison to "traditional" procedures, this new method is less tedious since chemical separation of plasmids is not required prior to electrophoresis. Also, a higher yield of plasmid …

A Three-Dimensional Bistatic Radar Target Position Measurement Error Model, Robert Kenneth Lynn

Masters Theses

"The accuracy of target position measurements for an airborne bistatic radar receiver are calculated. Two methods of information measurement are utilized, both of which assume cooperative synchronization between the transmitter and receiver. Gimbal angle errors are incorporated into both methods. The size and orientation of the error ellipsoid about the true target position is found. Loci of constant circular error probable are plotted in a horizontal plane of interest"--Abstract, page ii.

Aircraft Vertical Profile Implementation Using Directed-Graph Methods, L. T. Brewster, Paul D. Stigall

Electrical and Computer Engineering Faculty Research & Creative Works

Aircraft Vertical Profile Simulation is Realized using a Demand-Driven Minimal-Calculation Directed Graph Structure to Reduce Calculation Time and to Force Synchronization of the Performance Measurement Functions with the System State Variables. Performance-Directed Model Adaptation Makes Dynamic Vertical Profile Path Corrections, in the Presence of Fixed Drag Variations, Possible. Drag Variations Ranging from + 10 Percent to - 10 Percent Yielded Fuel Consumption Improvements of Less Than 1 Percent in the Majority of the Cases. Calculation Time Improvement for Path Simulation Ranges from a Factor of 1.19 in the Worst Case to 1.5 in the Best Case. © 1988 IEEE

Effect Of Excess Pbo On The Sintering Characteristics And Dielectric Properties Of Pb(Mg1/3nb2/3)O3–Pbtio3‐Based Ceramics, Jyoti P. Guha, Dyllan J. Hong, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

Additions of excess PbO to the perovskite Pb[(Mg_1/3Nb_2/3)_0.92Ti_0.08]O₃ solid solution enhanced the formation of a liquid phase at 840°C, which served as a densification aid for the ceramics. The liquid phase allowed elimination of pores and promoted grain growth during sintering. With additions of 1 to 2 wt% excess PbO, densities in excess of 97% of theoretical were obtained at a sintering temperature of 950°C. The peak dielectric constants of the resulting ceramics were over 18 000 at 30°C and dissipation factors less than 1%. Additions of PbO in excess of …

An Analysis Of The Abaca Natural Fiber In Reinforcing Concrete Composites As A Construction Material In Developing Countries, Rolando V. Magdamo

Dissertations and Theses @ UNI

This study was undertaken to analyze the flexural and splitting tensile strengths and the ductility of abaca fiber-reinforced concrete composites. Abaca fibers are natural fibers of vegetable origin prepared from the abaca plant which is a native plant of the Philippine Islands. The purpose of the study was to investigate how various volume-fractions of the abaca fiber in the concrete mix could affect the mechanical properties of the concrete matrix.

A concrete design mix containing a volume ratio of 1.0 part Type I Portland...cernent and 3.0 parts sand was utilized in the preparation of laboratory test samples. Abaca fibers were …

The System Design And Evaluation Of A Microprocessor Controlled Dispenser Using A Radar Ground-Speed Sensor, Yu-Charn Chen

Dissertations and Theses @ UNI

This experimental research focused on the design of a new approach to control seed dispensers and to analyze the performance characteristics of a Doppler radar ground speed sensor for a microprocessor control dispenser. The research focused on comparing the effectiveness of using a radar unit with a fifth-wheel encoder for measuring ground speed when both were connected to a microprocessor controlled seed dispenser.

The system designed for this study consisted of hardware and a computer program in 6502 assembly language. The hardware for this study consisted of a monitor device, microprocessor control unit, stepper motor, fifth-wheel encoder, Doppler radar and …

Condensation Method For Humidity Measurement In The Umr Cloud Simulation Chamber., Donald E. Hagen, Daniel R. White, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A Cloud Simulation Facility Has Been Developed for the Study of Various Atmospheric Cloud Processes. the Initial Relative Humidity of the Air Sample Put into the Cloud Chamber is a Key Parameter in Virtually Any Experiment and Needs to Be Known Accurately. This Report Describes How the Cloud Simulation Chamber itself Has Been Used as a Condensation Type Hygrometer to Calibrate the System's Humidifier. Two Distinct and Physically Different Methods for Inferring Mixing Ratio Are Used, One Exploiting the Sensitivity of Aerosol Activation to Humidity, and the Other Exploiting the Sensitivity of the Rate of Growth of Cloud Droplets to …

16 X 1 Nmos Static Random Access Memory Design, David W. Dougherty

Journal of the Microelectronic Engineering Conference

A Static Random Access Memory (SRAM) was designed using a 2 micron minimum geometry, nMOS fabrication process on an Apollo design station. In addition to the SRAN integrated circuit, test structures were included to help characterize the process and design. The chip contained over 200 transistors on a die size of 800 square microns. Simulation results predicted an access time of 50 nano—seconds. The pads were configured to fit a 20 pin probe card to facilitate automatic testing.

Approximate Methods For Analysis And Design Of Channel And Tee Shaped Reinforced Concrete Columns Under Axial Compression And Biaxial Bending, Chayan Bhattacharyya

Theses

Combined Bending and Axial Compression for irregular shaped (such as L-shaped, Channel shaped, T-shaped) reinforced concrete short column is a common design problem. Current code provisions and the available design aids do not offer an insight into the determination of strength and ductility of biaxially loaded reinforced concrete columns. The reason is that the information on the behavior of irregular shaped reinforced concrete members under combined biaxial bending and axial load is not well known. They are usually overdesigned and this may cause the structure to be stiffer, which may result in loss ductility when applied to seismic regions. Thus …

Microprocessor Controller For A Multi-Targets System, Shoeineng Lin

Theses

This thesis presents a microprocessor controller for a multi-targets system, which is designed by a direct digital control in the modern computer-aided manufacture system. It is made up of digital control theory, computer hardware configuration and software algorithm. An example is illustrated by IBM PC/XT computer. In this example, the control laws of three simple targets are developed and implemented by C-language. Simultaneously, the computer self-test routines, such as CPU, ROM etc, are developed by intel-8088 assembly language.

Interfacing Of The Digital Spyghnomanometer [Sic] Ds-165 To The Intel 8052ah Basic Based Single Board Computer, Rakesh P. Patel

Theses

The aim of this thesis is to collect the measured data from the blood pressure measurement unit to the single board computer and to store the data for the analysis purposes.

Application Of Computer Techniques In Groundwater Contamination Studies, Komratchi Raman

Theses

A study has been undertaken to provide insight into two related aspects of groundwater contamination studies - contaminant transport behavior and its analysis by modeling techniques. The study reviews recent research that explains some of the uncertainties in the transport and fate of chemical contaminants in groundwater. Approaches to modeling techniques and data reduction are developed to illustrate their usefulness in analysing existing groundwater data, and to make predictions on the future water chemical characteristics. Three types of study areas have been chosen for this purpose, each representing a different type of groundwater contamination problem. The first study area has …

On The Use Of A Modified Square-Well Model For Prediction And Correlation Of Thermal Diffusion Factors In Binary Liquid Mixtures, Richard L. Rowley, S. C. Yi

Faculty Publications

Recently reported thermal diffusion factors obtained from heats of transport have been used to test the ability of existing theories to predict thermal diffusivities using model parameters regressed from pure component transport data. None of the theories tested were able to provide even qualitative agreement with experiment. However, predictions using a square-well Enskog theory, modified here for consistency with normal experimental definitions, were found to be approximately correct using pure-component square-well parameters regressed from viscosity and thermal conductivity and an assumed mixing rule for cross terms. Predicted values are very sensitive to the energy mixing rule, and correlation of experimental …

Two-Dimensionat Studies Of Streamers Fn Gases, S. K. Dhali, P. F. Williams

P. F. (Paul Frazer) Williams Publications

We present the results of two-dimensional computer simulations of streamer initiation and propagation in atmospheric pressure N₂. The simulation algorithm makes use of flux-corrected transport techniques and was used as a tool to study the solutions of the transport equations under conditions suitable for streamers, for which realistic analytic solutions are not known. We present and discuss conclusions about streamer transport based on the results of these studies. Finally, we present a novel method of checking on the numerical accuracy with which the algorithm solves the transport equations.

Heats Of Transport From Diffusion Thermoeffect Measurements On Binary Liquid Mixtures Of Carbon Tetrachloride With Benzene, Toluene, 2-Propanone, N-Hexane, And N-Octane, Richard L. Rowley, S. C. Yi

Faculty Publications

Measurements of heats of transport are reported for binary liquid mixtures containing carbon tetrachloride and benzene, toluene, 2-propanone, n-hexane, or n-octane at 298 K and ambient pressure. Additionally, measurements were made at 308 K for carbon tetrachloride with benzene, toluene, and 2-propanone. The corresponding heat-mass Onsager coefficients are also reported, from which thermal diffusion ratios have been calculated based on Onsager reciprocity. These data will be used in a companion paper to report a modified Enskog method for correlation and prediction of heats of transport.

Hyperbolic Soil Parameters For Granular Soils Derived From Pressuremeter Tests For Finite Element Programs, Dieter Neumann

Dissertations and Theses

In the discipline of geotechnical Engineering the majority of finite element program users is familiar with the hyperbolic soil model. The input parameters are commonly obtained from a series of triaxial tests. For cohesionless soils however, today's sampling techniques fail to provide undisturbed soil specimen. Furthermore, routine triaxial tests can not be carried out on soils with grains exceeding 10 - 15 mm in size.

Initial developments towards a link between high quality pressuremeter tests and the hyperbolic finite parameters element input are presented. Theoretical and empirical approaches are used to determine the entire set of and from pressuremeter tests. …

Removal Of Eucalyptus Vessel Segments Using Centrifugal Cleaners, Amnuay Ponpued

Masters Theses

Two commercial feedforward centrifugal cleaners were used in the study of vessel segment removal from bleached eucalyptus pulp. The reduction of vessel elements yielded a reduction of vessel pick tendency and other problems caused by vessel elements which limit the use of eucalyptus pulp in paper stock furnishes. The operating conditions of the centrifugal cleaners were evaluated for their effect on separation efficiency. Pulp loss with rejects was reduced by multiple stage separation. The Vandercook Proof Press was used to compare the picking of cleaned, original pulp and two higher-vessel-content pulps. Regression analysis and ANOVA showed significant effects of feed …

A Laboratory Simulation Of A Rotary Vacuum Drum Brownstock Washer, Hugh E. Muller

Masters Theses

Mass balances can quantify the dilution and thickening of a liquor/fiber suspension on a brownstock washer. However, the complex displacement process necessitates an empirical approach. Given empirical data, washers can be optimized through use of efficiency factors with mass balances.

Because empirical data is difficult to obtain, a laboratory washing method was developed to empirically generate displacement efficiencies on pulp under mill washer conditions. Reproducible data generated by this method resulted in a displacement/dilution function as seen on mill washers. A laboratory simulation using mill samples, exclusive of problems for one vacuum drum, resulted in comparable efficiencies with less than …

Generalized Linear Inversion Using Tau-P Forward Modeling, Stephen Dade Walker

Graduate Theses

The Generalized Linear Inversion (GLI) method is used in conjunction with a tau-p forward model to successfully perform inversions of test and real-data examples. All data examples used are one-dimensional velocity profiles that represent several different cases. The stability of the technique is demonstrated in all the test-data sets. The use of simple models and wel1-control 1ed test data results in a minimum of iterations of the inversion process. Different levels of perturbation of the model and test-data examples are used to reveal insight into the robust nature of the inversion.

Evaluation Of Unmanned Radar Installations, Jerry G. Pigman, Kenneth R. Agent, John A. Deacon, Richard J. Kryscio

Kentucky Transportation Center Research Report

Several unmanned radar devices were installed on I75 in northern Kentucky in an attempt to reduce speeds. It was assumed that drivers use radar detectors to exceed the speed limit with a resulting variance between their speeds and others in the traffic stream. Therefore, a reduction in overall speeds and variance was expected to reduce the probability of accidents. Historical data indicated an unusually high accident rate for the study area.

Emphasis was placed on collection and analysis of speed-related data. In addition, a survey of radar detector usage was made and accident patterns were documented.

Speed measures analyzed included …

A Computer Simulation Of The Rotary Drum Brownstock Washer System Using The Monte Carlo Method Of Distribution Sampling, Jacqueline K. Pease

Masters Theses

A steady-state probabilistic model is chosen to simulate the brownstock washing system's uncertainty which arises from unpredictable process fluctuations and measurement noise. Distribution sampling is used to construct multiple mass balances of a washing system. Included in this model is a linear relationship describing the correlation between dilution and displacement which allows displacement ratio to be generated based on dilution factor. This is an improvement over a similar, earlier model which considers all variables to be independent. There is no statistical difference between the mean output of the simulation and the means of data sets collected at two different mills. …

Theoretical Thermodynamic Properties Of Low Temperature Fluids, Zul Azhar Zahid Jamal

Masters Theses

The thermodynamic functions for low temperature fluids are computed using parametric integral equations and perturbation theory. Parametric integral equation N is applied to a low temperature Lennard-Jones gas. It is found that there is no significant improvement over the better known parametric integral equation C. The two parameter integral equation T is applied to a low temperature square-well potential and is found to be unsatisfactory at reduced temperatures of T*= 1.4 and 1.6, but quite accurate at T* = 2.2. The equation T results for T* = 2.2 are used as the reference system in perturbation theory computations. Tables of …

University Of Missouri-Rolla Cloud Simulation Facility: Proto Ii Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, Alfred R. Hopkins, Max B. Trueblood, Max W. Alcorn, William L. Walker

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Graduate Center for Cloud Physics Research at UMR Has Developed a Cloud Simulation Facility to Study Phenomena Occurring in Terrestrial Clouds and Fogs. the Facility Consists of a Pair of Precision Cooled-Wall Expansion Chambers Along with Extensive Supporting Equipment. the Smaller of These Chambers, Described in This Article, is Fully Operational, and is Capable of Simulating a Broad Range of In-Cloud Thermodynamic Conditions. It is Currently Being Used to Study Water Drop Growth and Evaporation for Drops Nucleated (Activated) on Well-Characterized Aerosol Particles. Measurements Have Been Made Not Only for Continuous Expansions (Simulated Updraft) But Also for Cyclic Conditions, …

Definition Of An Asymmetric Domain For Intercrystalline Misorientation In Cubic Materials In The Space Of Euler Angles, Brent L. Adams, Junwu Zhao

Faculty Publications

The authors wish to acknowledge the support of the United States Department of Energy, Office of Basic Energy Sciences, under grant No. DE-FG02-85ER45203. Critical review by Professor Dorian Hatch of the Physics Department at Brigham Young University is gratefully acknowledged. A new asymmetric domain for intercrystalline misorientation is defined in the space of Euler angles for materials exhibiting cubic (Oh point-group) lattice symmetry. The invariant measure for this new domain is nearly constant; this is in significant contrast to the previous domain defined by MacKenzie [Biornetrika (1958), 45, 229-240]. Distribution functions in the misorientation can now be represented with greater …

Strength And Fracture Toughness Of Steel Fibre Reinforced Mortar, Moussa Mahmoud Shouman

Archived Theses and Dissertations

No abstract provided.

Irish H & V News

Building Services Engineering

No abstract provided.