Engineering Commons^™

Development And Testing Of A Cfd-Based Optimization System For Axially Symmetric Rocket Nozzles, John-Paul Shebalin

Mechanical & Aerospace Engineering Theses & Dissertations

A software system has been developed to optimize rocket nozzle shapes for maximizing their performance. It has been established in the literature that one can use computer-based optimization with the parabolized Navier-Stokes equations to optimize the dimensions of low Reynolds number rocket nozzles-micronozzles. The Nozzle Optimization System described herein uses the full Navier-Stokes equations to optimize any axially symmetric rocket nozzle for which a converged solution can be obtained.

Four nozzles are optimized using this system-conical and contoured micronozzles and conical and contoured Space Transportation System(STS)-class nozzles. The optimum cone angle (O_cone) for the conical micronozzle was …

Time-Resolved Electron Diffraction Studies Of Phase Transitions At Low-Index Germanium Surfaces, Xinglin Zeng

Electrical & Computer Engineering Theses & Dissertations

The phase transitions at the low-index surfaces of germanium were investigated using conventional and 100-ps time-resolved reflection high-energy electron diffraction. For the time-resolved studies, the surface is heated by 100-ps laser pulse while a synchronized electron beam probes the structure. When heated by 100-ps laser pulse, Ge(111)-c(2x8) and Ge(100)-(2x1) reconstruction is seen to overheat above the onset temperatures for the disordering under thermodynamic equilibrium. Slow heating shows that the adatoms in the Ge(111)-c(2x8) reconstruction state start to disorder at ∼510 K and are converted to a totally disordered adatom arrangement at 573 K. For heating with 100-ps laser pulses, time-resolved …

On Multifunctional Collaborative Methods In Engineering Science, Jonathan B. Ransom Sr.

Mechanical & Aerospace Engineering Theses & Dissertations

Engineers are challenged to produce better designs in less time and for less cost. Hence, to investigate novel and revolutionary design concepts, accurate, high-fidelity data must be assimilated rapidly into the design, analysis and simulation process. This data assimilation should consider diverse mathematical modeling and multi-discipline interactions necessitated by concepts exploiting advanced materials and structures. Integrated high-fidelity methods with diverse engineering applications provide the enabling technologies to assimilate these high-fidelity, multi-disciplinary data rapidly at an early stage in the design. These integrated methods must be multifunctional, collaborative and applicable to the general field of engineering science and mechanics.

Multifunctional methodologies …

A Substructuring Technique With Application To Spot Weld Placement Design, Yang Wang

Mechanical & Aerospace Engineering Theses & Dissertations

It is quite common in the industry to use various interface methods, such as welding, fasteners, bolts, adhesive bonding, etc., to join substructures together. The quality of the assembled structure is directly related to the type of the interface methods used in the manufacturing process. Thus, it is important to include the interface conditions as part of design variables in any design process. To this end, this work develops a reanalysis method that can efficiently analyze structures with variations on the interface conditions. This reanalysis method is based upon a new two-step substructuring technique. The first step performs substructural level …

Study Of Automotive Hydromount Mechanism, Min Lu

Dissertations

The hydromount mechanism is studied. It was determined that the dynamic characteristics of the hydromounts are related to the rubber static stiffness, rubber damping coefficient, volumetric stiffness, and effectiveness of the oscillating fluid in the inertia track. At high frequencies the motion of the fluid in the inertia track diminishes so that its effect is negligible and may be ignored. It is also concluded that the rubber damping has a minimal effect on the hydromount dynamic properties and may be neglected. The maximum loss angle, which corresponds to the maximum damping coefficient of the hydromount, occurs near the inertia track …

Enhancing Commercial Aircraft Survivability Via Active Venting, Roger L. Veldman

Dissertations

A new technique for enhancing aircraft safety in the event of an on-board explosion was studied. The method under study employs deployable vent panels located on the fuselage which are activated by an array of pressure sensors in the aircraft interior. In the event that an explosion is detected, appropriate vent panels are rapidly released from the aircraft. This approach seeks to provide timely relief of explosive pressures within an aircraft to prevent catastrophic structural failure.

In this study, the approximate time scale of an explosive detonation and the subsequent sensing and electronic processing was determined. Then, the actuation response …

Innovative Financing Options For Kentucky’S Transportation Infrastructure, Merl M. Hackbart

Kentucky Transportation Center Research Report

A strong linkage exists between economic growth and the availability of an adequate and efficient transportation system. Due to its location, geography and economy, this linkage — particularly in regard to highway transportation — is critical to continued economic progress in the Commonwealth of Kentucky. However, Kentucky’s ability to provide the infrastructure investments needed to be competitive in the new “global economy” is constrained by the structure of its funding mechanism, the Road Fund. During the last two decades, Road Fund revenue growth has dramatically lagged the growth of motor vehicle travel. As a consequence, Kentucky faces highway investment needs …

Wear And Friction Behavior Of Pressure Infiltration Cast Copper-Carbon Composites, G. Göller, D. P. Koty, M. Singh, A. Tekin

Chemical & Biomedical Engineering Faculty Publications

Metal matrix composites, prepared by pressure infiltration casting of copper base alloy into 2 types of microporous carbon preforms, one with 100% amorphous carbon and the other containing 40 wt pct. graphite and 60 wt pct. amorphous carbon, have been examined for their wear and friction behavior under ambient conditions using a pin-on-plate reciprocating wear tester. Micro-structural characterization of tribo-surfaces has been carried out. The thin carbon films formed on the tribo-surface reduced the friction coefficient and wear for the composites, especially at low loads on the pin. Adhesive wear observed on the tribo-surface promoted wear and …

Modeling Nonlinear Behavior In A Piezoelectric Actuator, Hanz Richter, Eduardo A. Misawa, D. A. Lucca, H. Lu

Mechanical Engineering Faculty Publications

A piezoelectric tube actuator is employed as a sample positioning device in Nanocut, a cutting instrument conceived to study the mechanics of nanometric cutting. Extension of functionality of the instrument as a nanometric machine tool motivates the search for an accurate model of the actuator for implementing feedback control. A simple nonlinear model describing longitudinal expansion of the piezoelectric tube actuator is presented in this paper. The model derivation is based on a non-formal analogy with nonlinear viscoelastic materials under uniaxial extension, for which the responses to a step input are similar to the piezoelectric tube. Suitability of the …

The Fixed Weighting Nature Of A Cross-Evaluation Model, Timothy R. Anderson, Keith Hollingsworth, Lane Inman

Engineering and Technology Management Faculty Publications and Presentations

Cross-evaluation has been touted as a powerful extension of Data Envelopment Analysis that provides, not only a unique ordering among the Decision Making Units (DMUs), but also eliminates unrealistic weighting schemes without requiring the elicitation of weight restrictions from application area experts. The goal of this paper is to prove, in the single-input, multiple-output case, cross-evaluation implicitly uses a single fixed set of weights. We demonstrate how this unseen fixed set of weights may still be unrealistic.

Quality Control Parameters For Robotic Bridge Painting, Yong Bai, Leonhard E. Bernold

Civil and Environmental Engineering Faculty Research and Publications

To protect a steel bridge from corrosion, periodic painting is needed. Bridge painting operations are dangerous and hazardous to human health. A robotic bridge painting system is being developed to replace the human being. One major problem with robotic bridge painting is how to achieve the specified coating quality, which includes two aspects: (1) the coating thickness; and (2) the coating appearance. To ensure quality of the robotic bridge painting, the writers have investigated: (1) the parameters that affect the coating thickness and appearance; (2) the values of the parameters to achieve the required thickness and appearance for the robotic …

Bs News

Building Services Engineering

No abstract provided.

Spice-Based Heat Transport Model For Non-Intrusive Thermal Diagnostic Applications, Michael Stelzer

Electrical & Computer Engineering Theses & Dissertations

Nondestructive material testing and diagnostics play an important role in reliability analysis, component wear-out testing, life-cycle estimates, and safety inspections. Of the several techniques available for nondestructive inspections, thermal analysis has been chosen to be the focus of this thesis research. An equivalence between the system of equations for the heat flow problem, and the variables of circuit theory suggests that an electrical model can be constructed to represent the actual thermal system. This electrical model is constructed based upon a finite difference discretization of the heat flow equation. Using these associations a basic one-dimensional electrical model has been constructed …

A Compact Ozone Differential Absorption Lidar (Dial) Transmitter Using A Solid-State Dye Polymer, Alton L. Jones Jr.

Electrical & Computer Engineering Theses & Dissertations

The measurement of atmospheric ozone is important because in the troposphere it is a pollutant that is toxic to living systems, but in the stratosphere ozone protects life by shielding us from the sun's harmful UV-B radiation.

Laser remote sensing from aircraft using differential absorption lidar (DIAL) has become a very important technique for measuring atmospheric ozone at different altitudes and locations. Current aircraft-based DIAL systems use pulsed Nd:YAG pumped liquid dye lasers, which are then frequency doubled into the UV region, to probe both the stratosphere and troposphere for ozone.

This thesis describes a new potential DIAL laser transmitter …

Adsorption Of Inorganic And Organic Ligands Onto Aluminum Hydroxide And Its Effect In Water Treatment, Peter Pommerenk

Civil & Environmental Engineering Theses & Dissertations

The inorganic anions fluoride, sulfate, and orthophosphate are ubiquitous substances in aqueous environments. These chemicals are also applied in drinking water treatment processes where fluoridation, coagulation with sulfate-based metal salts, or the use of passivating corrosion inhibitors or sequestering agents is practiced. If these ions are present at elevated levels in raw waters or added in the treatment train at points other than directly before entering a finished water reservoir, they can exert a negative influence on the removal of particles and natural organic matter.

Although the water chemistry of these inorganic ions seems to be well understood, their potential …

Unsteady Flow Model For An Irrigation Canal Network, Talaat Taher El Gamel

Civil & Environmental Engineering Theses & Dissertations

A mathematical model is developed to route unsteady flow through an irrigation canal network. The model is designed to handle branches, lateral inflow and outflow, sluice gates, and various boundary conditions. The model is developed for use on a personal computer. A specific irrigation canal network in Egypt is used as a case study to verify the model, and the results are presented. Full documentation is included in the appendix.

Simultaneous Capture And Mineralization Of Coal Combustion Flue Gas Carbon Dioxide (Co2), Morris D. Argyle, Katta J. Reddy, Sanil John, Hollis Weber, Pradip Bhattacharyya, David T. Taylor, Mikol Christensen, Thomas Foulke, Paul Fahlsing

Faculty Publications

The mineral carbonation, a process of converting CO2 into stable minerals (mineralization), has been studied extensively to capture and store CO2. However, most of the mineral carbonation studies have been largely investigated at lab scale. Preliminary and pilot scale studies for accelerated mineral carbonation (AMC) were conducted at one of the largest coal-fired power plants (2120 MW) in the USA by reacting flue gas with fly ash particles in a fluidized bed reactor. In the preliminary experiments, flue gas CO2 and SO2 concentrations decreased from 13.0 to 9.6% and from 107.8 to 15.1 ppmv, respectively during the first 2 min. …

Coherent Differential Absorption Lidar For Combined Measurement Of Wind And Trace Atmospheric Gases, Grady James Koch

Electrical & Computer Engineering Theses & Dissertations

A lidar system was developed for making combined range-resolved measurements of wind speed and direction, water vapor concentration, and carbon dioxide concentration in the atmosphere. This lidar combines the coherent Doppler technique for wind detection and the differential absorption lidar (DIAL) technique to provide a multifunctional capability. DIAL and coherent lidars have traditionally been thought of and implemented as separate instruments, but the research reported here has shown a demonstration of combining the coherent and DIAL techniques into a single instrument using solid-state lasers. The lasers used are of Ho:Tm:YLF, which operates at a wavelength of 2 μm. This wavelength …

Bridge Programs: A Strategic Partnership, Tim Brady

Publications

The results of a study commissioned by the National Business Aviation Association discussing factors related to alleviating airline pilot shortages. By utilizing universities with existing pilot training programs, universities are able to train new pilots in company-specific procedures. This bridge program allows the company to interface with the university and influence curriculum design.

Elastic Properties, Strength And Damage Tolerance Of Pultruded Composites, Mrinal Chandra Saha

Mechanical & Aerospace Engineering Theses & Dissertations

Pultruded composites are candidate materials for civil engineering infrastructural applications due their higher corrosion resistance and lower life cycle cost. Efficient use of materials like structural members requires thorough understanding of the mechanism that affects their response. The present investigation addresses the modeling and characterization of E-glass fiber/polyester resin matrix pultruded composites in the form of sheets of various thicknesses.

The elastic constants were measured using static, vibration and ultrasonic methods. Two types of piezoelectric crystals were used in ultrasonic measurements. Finally, the feasibility of using a single specimen, in the form of a circular disk, was shown in measuring …

Fourth International Conferences On Recent Advances On In Geotechnical Earthquake Engineering And Soil Dynamics, Multiple Authors

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Processing Of Erbium Doped High-Tc Superconductor Yba2cu3o7-X Single Crystals For Improved Flux Pinning, William C. Hicks, Fatih Dogan, Michael Strasik, Arthur C. Day, Kevin E. Mccrary

Materials Science and Engineering Faculty Research & Creative Works

The effect of selected Rare Earth (RE) oxide addi- Tion on growth behavior of large single crystals and the super- conducting properties of YBa₂Cu₃0_7-x, (Y123) was investigated. The results show that even a small amount (cl mol %) of rare earth addition can have a significant effect on the flux pinning capacity of Y123 single crystals. It was further observed that for Nd and Yb the continuous crystal growth became very unstable for additions greater then 1 mol % while crystal growth remains stable even for additions up to 30 mol % Er_{2 …}

Processing Of Erbium Doped High-Tc Superconductor Yba2cu3o7-X Single Crystals For Improved Flux Pinning, William C. Hicks, Fatih Dogan, Michael Strasik, Arthur C. Day, Kevin E. Mccrary

Materials Science and Engineering Faculty Research & Creative Works

The effect of selected Rare Earth (RE) oxide addition on growth behavior of large single crystals and the super- conducting properties of YBa₂Cu₃O_7-x, (Y123) was investigated. The results show that even a small amount (cl mol %) of rare earth addition can have a significant effect on the flux pinning capacity of Y123 single crystals. It was further observed that for Nd and Yb the continuous crystal growth became very unstable for additions greater then 1 mol % while crystal growth remains stable even for additions up to 30 mol % Er₂BaCuO …

Cfd Modeling Of Multiphase Flow Distribution In Catalytic Packed Bed Reactors: Scale Down Issues, Y. Jiang, Mohan R. Khadilkar, Muthanna H. Al-Dahhan, Milorad P. Dudukovic

Chemical and Biochemical Engineering Faculty Research & Creative Works

Flow Maldistribution in Either a Bench-Scale or Commercial Scale Packed Bed is Often Responsible for the Failure of the Scale Down Unit to Mimic the Performance of the Large Reactor. the Modeling of Multiphase Flow in a Bench-Scale Unit is Needed for Proper Interpretation of Reaction Rate Data Obtained in Such Units. Understanding the Mechanism of Flow Maldistribution is the First Step to Avoiding It. in Order to Achieve This Objective, Computational Fluid Dynamic (CFD) Simulations of Multiphase Flow under Steady State and Unsteady State Conditions in Bench-Scale Cylindrical and Rectangular Packed Beds Are Presented for the First Time. the …

2001 - The Sixth Annual Symposium Of Student Scholars

Symposium of Student Scholars Program Books

The full program book from the Sixth Annual Symposium of Student Scholars, held on March 30, 2001. Includes abstracts from the presentations and posters.

The Other Information Warfare: A Mind Full Of Macedonia, Ibpp Editor

International Bulletin of Political Psychology

This article highlights ongoing aspects of psychological warfare in Macedonia between government and rebel forces.

Photographic Ensemble - Opening Ceremonies, Multiple Participants

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

No abstract provided.

Photographic Ensemble - Posters, Multiple Participants

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

No abstract provided.

Photographic Ensemble - Conference Banquet, Multiple Participants

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

No abstract provided.

Comparison Of Frequency Spectra For Micotremors, After Shocks (M=2.5-4.7) And The Main Shock Of The Spitak Earthquake Obtained On Massive Lake-River Formations In The Region Of Giumry (Armenia), Hrachya Abrahamyan

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

On December 7, 1988 a disastrous earthquake with magnitude M=7.0 took place in the northern part of Armenia, during which in Giumry (former Leninakan) large-scale destruction of standardized buildings with epicentral distance 35 km was observed. This forced us to set a task: to find connection between large-scale destruction and some dynamic peculiarities of grounds on the territory of the city. The present article makes an attempt to explain the significance of the upper engineering-geological stratum (20-30 m) and that of the lower massive lake-river formations. Basing ourselves on a great number of instrumental observations we tried to compare prevailing …