Engineering Commons^™

A Comparison Of Computational And Experimental Data For A Subscale High Speed Propulsive Nozzle At Low Mach Numbers, Yonghee Hyun

Theses and Dissertations

This computational study of a hypersonic sub-scale nozzle/cowl configuration compares numerical solutions with experimental data for nozzle performance at off design conditions (subsonic through supersonic Mach numbers. A combination of Van Leer and Roe flux-splitting algorithms was used to solve the flow field. The explicit formulation assumed laminar planar flow and the perfect gas equation of state. A validation for the numerical algorithm was accomplished by comparing with experimental data for a variety of cases. Grid refinement, geometry, and operating conditions all influenced the comparison of the experimental and computational data. Generally, as the Mach number and nozzle pressure ratio …

Experimental Investigation Of The Effects Of Blowing Ratio Parameter On Heat Transfer To A Film-Cooled Flat Plate, Marco R. Valencia

Theses and Dissertations

The effects of blowing ratio on film cooling effectiveness were investigated. Two round-nosed test plates were used. One made of aluminum and the second of corian (low thermal conductivity). Injection at 35 degrees in the downstream direction was studied. Helium was mixed with air to produce a density ratio (coolant to mainstream) of 1.6 and 2.0, while the blowing ratio varied from 0.3 to 2.2. Surface temperature was measured by thin film gages located up to a nondimensional downstream distance X/D of 30. Two injection regimes, weak and strong, were found. In the weak regime, film cooling reduced gage heat …

Development Of An Air-To-Air Refueling Automatic Flight Control System Using Quantitative Feedback Theory, Dennis W. Trosen

Theses and Dissertations

Quantitative Feedback Theory and the improved method Quantitative Feedback Theory are enhanced to include the rejection of disturbance at the system output. The enhanced Quantitative Feedback Theory and improved method Quantitative Feedback Theory processes are applied to the design of an automatic flight control system to regulate position of the C-135B fuel receiving aircraft relative to the tanker during air-to-air refueling. A simple feedback control system is developed that will achieve stable position regulation. State-space aircraft models &re generated. An inner loop autopilot is designed to reduce the plant cutoff frequency and provide the system inputs for the Quantitative Feedback …

Spectroscopic Ellipsometry Studies Of Hf Treated Si (100) Surfaces, Huade Yao, John A. Woollam, Samual A. Alterovitz

Department of Electrical and Computer Engineering: Faculty Publications

Both ex situ and in situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effects of HF cleaning on Si surfaces. The hydrogeniterminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:l HF dip without rinse, the Si ( 100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated …

Construction And Interim Performance Of A Pyrament Cement Concrete Bridge Deck, Michael D. Stone, David Q. Hunsucker

Kentucky Transportation Center Research Report

Pyrament Blended Cement (PBC) is a high performance cement developed by Lone Star Industries and is a blend of 65% portland cement, 30% fly ash, and 5% trademark additive. Concrete made with PBC has been characterized by its rapid set, high early strength, and low permeability. This report summarizes the construction and interim performance of a full-depth concrete bridge deck slab constructed using Pyrament Cement concrete.

Utilization Of Fossil-Fuel Related By-Product Materials For Highway Construction In Kentucky, David Q. Hunsucker

Kentucky Transportation Center Research Report

In an effort to increase the utilization of fossil-fuel by product materials in highway construction project, the Kentucky Transportation Cabinet authorized the experimental use of several waste materials. These materials included bottom ashes, fly ash, scrubber sludge, multicone kiln dust, and residues tram atmospheric fluidized bed combustion processes. Bottom ash aggregate was used as a partial replacement for the limestone aggregate in a bituminous surface mix. Non-specification fly ash was used in lieu of Class F fly ash in a stabilized aggregate base. Bottom ash stabilized with residue from an atmospheric fluidized bed combustion process was used as a highway …

Performance Of Experimental Highway Base And Subbase Layers Containing Coal-Fired Power Plant By-Product Materials: Ky Route 3074, Bleich Road, David Q. Hunsucker, R. Clark Graves

Kentucky Transportation Center Research Report

Three 750-foot test sections of a 22-foot wide roadway were constructed on newly constructed subgrade in May and June, 1988. The three experimental sections contained experimental base and subbase layers comprised of mixtures utilizing by-product materials from a coal-fired power plant One test section included a base layer containing residue from an atmospheric fluidized bed combustion (AFBC) process, size No. 57 aggregate, and Class F fly ash. The second test section included a base layer constructed ponded fly ash, hydrated lime, and dense-graded aggregate. The third test section included a subbase layer constructed of pond ash stabilized with AFBC residue. …

Bs News

Building Services Engineering

No abstract provided.

Investigation Of Traffic Induced Ground Vibration By Random Process Theory, J. Benčat

International Conference on Case Histories in Geotechnical Engineering

The ground motion is caused by vibration propagation due to moving vehicles. Ground vibration recorded at a distance from a busy roadway or railway is analyzed assuming it to be a random and statistically stationary function of time. The soil media are characterized as the visco- elastic halfspace. The analytical method for predicting ground vibration has been described. The spectral density of ground vibration for a particular case was calculated and the prediction is validated by experimental measurement.

Dynamic Response Of Block Foundations, Vijay K. Puri, Braja M. Das

International Conference on Case Histories in Geotechnical Engineering

This paper presents the results of comparison of the computed and observed response of two block foundations made of concrete. The test blocks measuring 3.0m x 1.5m x 0.7m and 1.5m x 0.75m x

0.70m were cast on level ground. The blocks were excited into vertical vibrations using a speed controlled mechanical oscillator. The amplitudes of vibration at different frequencies of excitation were measured in each case using acceleration transducers mounted on appropriate faces of the block. Dynamic shear modulus at this site was also determined b¥ conducting in-situ tests namely the wave propagation test, the cyclic plate load test, …

Dynamic Compaction Test On An Hydraulic Silty Sand Fill, G. Varosio, P. Grimaldi, G. Canepa

International Conference on Case Histories in Geotechnical Engineering

Dynamic compaction resulted to be the most effective method to compact a very loose hydraulic silty sand fill, with a fine content from 25 to 90 per cent. Two levels of compaction energy were tested. The soil settlements enforced by these energies were verified with reference to the concept of saturation energy and by means of a simplified analysis of the physical model.

Correlation Of Foundation Vibration Results, R. A. Slabbaert, J. P. Lee, J. A. Bohinsky

International Conference on Case Histories in Geotechnical Engineering

The vibration a paper machine generates during normal operation presents a complicated challenge to engineers of paper machine support structures. The modeling and the analysis procedure inevitably involves many simplifications and assumptions. Therefore, a comparison of the calculated and the measured results is very helpful in assessing the validity of the overall approach. This paper discusses correlation of calculated paper machine vibration with actual field measurements for a specific paper machine installation. A force-response analysis was performed using a commonly accepted industry practice which is generally considered to be conservative in several areas. Subsequently, field vibration measurements were made. The …

Behavior Of Braced Sheetpile Excavation In Detroit Clay, H. Abedi, T. G. Porter, B. H. Lien, J. A. Ramos

International Conference on Case Histories in Geotechnical Engineering

This paper presents the design criteria, finite element modeling and actual behavior of a braced sheetpile excavation in Detroit soft clay. Due to the close proximity of existing structures to the excavation, a detailed analysis was performed to design and construct an earth retention system to avoid damage to these structures. The excavation involved a 170 ft by 220 ft area. The maximum depth of excavation was 23.5 ft. The subsurface soil consists of soft to very soft Detroit clay from the excavation level to a depth of 80 ft and has an undrained shear strength as low as 360 …

Behavior Of Deep Excavations Using Sheet Pile Bracing System In Soft Bangkok Clay, Wanchai Teparaksa

International Conference on Case Histories in Geotechnical Engineering

The sheet pile bracing system is the most well-known for excavation work in Bangkok soft marine clay. The sheet pile wall which is defined as flexible wall will show a large significant of lateral deformation and ground surface settlement if the excavation system is carried out without a good quality control. The sheet pile bracing system with fully effective preloading strut system was designed for basement excavation of 11.3 m. deep of Bai Yok Tower II. The results indicate that berm width can reduce the maximum sheet pile wall deflection only at the first three stages of excavation. The fully …

Measurements Of Seismic Road Vibrations, L. T. Long

International Conference on Case Histories in Geotechnical Engineering

Vibrations from vehicles on adjacent roads can impact sensitive instruments or structures with historic significance. The amplitudes of vibrations (A) from steady traffic in Atlanta, Georgia, were found to decay with distance (r) according to the relation Log[A(mm/s) ]=0.9-1.25Log(r(m)]. Intervening topographic relief reduces the level of vibration. Using this relation, the impact of a proposed highway was estimated to cause an 8 percent degradation in photographic images with telescope. A topographic barrier could reduce, but would not eliminate the impact of highway vibration. In a second application, a freeway access ramp was originally planned close enough for the vibrations from …

General Report Session No. 4: Case Histories Man-Made Vibrations, Vijay K. Puri, James P. Lee

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Discussions And Replies Session 4, M. R. Svinkin, G. M. S. Manyando, M. R. Lewis, J. R. Davie, X. J. Yang, G. Y. Gao

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Feasible Offset And Optimal Offset For Single-Layer Channel Routing, Ronald I. Greenberg, Jau-Der Shih

Computer Science: Faculty Publications and Other Works

The paper provides an efficient method to find all feasible offsets for a given separation in a VLSI channel routing problem in one layer. The prior literature considers this task only for problems with no single-sided nets. When single-sided nets are included, the worst-case solution time increases from Theta(n) to Omega(n^2), where n is the number of nets. But, if the number of columns c is O(n), one can solve the problem in time O(n^{1.5}lg n ), which improves upon a `naive' O(cn) approach. As a corollary of this result, the same time bound suffices to find the optimal offset …

Constitutive Equation For Concrete Using Strain-Space Plasticity Model, Yuxiang Xing

Dissertations

Plasticity theory has been used to model the concrete constitutive relationship for about two decades. With the modifications and refinement based on experimental data, achievement has been made in these plasticity models for concrete. Almost all the existing models are developed in stress space. With a lot of experimental data and more understanding about stress states of concrete, the stress-space model shows many advantages. Because of this and also due to conventional engineering practice, the stress-space plasticity approach has been in the dominant position. However, the conventional stress-space plasticity method has one inherent drawback in which it cannot deal with …

On Orthogonal Collocation Solutions Of Partial Differential Equations, Herli Surjanhata

Dissertations

In contrast to the h-version most frequently used, a p-version of the Orthogonal Collocation Method as applied to differential equations in two-dimensional domains is examined. For superior accuracy and convergence, the collocation points are chosen to be the zeros of a Legendre polynomial plus the two endpoints. Hence the method is called the Legendre Collocation Method. The approximate solution in an element is written as a Lagrange interpolation polynomial. This form of the approximate solution makes it possible to fully automate the method on a personal computer using conventional memory.

The Legendre Collocation Method provides a formula for …

Minimum Redundancy Array Structure For Interference Cancellation, Wan-Ling Chen

Dissertations

Adaptive antenna arrays are widely used in many advanced radar, sonar, and communication systems because of their effectiveness in cancelling intentional or unintentional interferers. A uniformly spaced linear array, referred to as a Uniform Regular Array (URA), is the usual structure used for interference cancellation. The Minimum Redundancy Array (MRA) structure proposed in this work is a special kind of thinned array whose application was limited in the past to direction finding. MRAs with the same number of array elements can resolve directions of much more closely spaced signals than URAs.

The URA structure is customarily utilized for interference cancellation, …

Tensile Behavior Of Concrete And Mortar Under Direct Impact Tensile Load, Kayumars Emad

Dissertations

Structures are often subjected to impact loadings during their lifetime. Most structural specifications including the special provisions for seismic design in the current ACI building codes, have been developed on the basis of quasi-static assumptions. Cement composites are strain rate sensitive materials therefore, their properties determined under quasi-static condition should not be used to predict their performance under high strain rates.

The objectives of this investigation are:

• to develop a standard test set-up for direct tensile testing of cementitious composites.
• to study the tensile behavior of mortar and concrete under direct impact tensile load.
• to develop a simplified formula to …

Characterization Of Advanced Etching Reactors Using Novel Diagnostic Tools, Vipulkumar Patel

Dissertations

Plasma etching equipment used for sub-micron integrated circuit fabrication at present are exclusively based on 13.56 MHz, capacitively coupled, parallel-plate geometry. The underlying mechanisms of plasma processes in these reactors are not well understood and there is even less understanding of how the etch-tool parameters relate to the plasma discharge characteristics which actually determine the etch process. In this thesis, new diagnostic techniques were applied for the characterization and optimization of plasma etching processes in various reactor configurations.

Specifically, diode and triode configurations were studied extensively using tuned scanning Langmuir probes. Both radial and axial distributions of plasma density were …

Kinetic Study Of Decomposition Of Azo Dyes And Phenol In Advanced Oxidation Processes Reaction Mechanisms, Pathways And Intermediates, Hung-Yee Shu

Dissertations

Advanced Oxidation Processes (AOP) are an emerging technology for treatment of various hazardous organics in wastewater and groundwater. However, the kinetics and mechanisms for AOP have not been well understood. A mechanism including light intensity was studied for the decomposition of azo dyes and phenol in an AOP reactor with a 5,000 watt low pressure mercury lamp. UV light absorption is an important parameter. The effect of pH, hydrogen peroxide dosage, and dye concentration on the decomposition of azo dyes in an H₂O₂/UV reactor were also studied. Reaction pathways and intermediates of phenol oxidation by different …

Unreinforced Masonry Structures : Nonlinear Analysis And Evaluation Of Some Rehab Schemes, Sanjay Mehta

Dissertations

Unreinforced masonry (URM) structures have been a common type of construction in the past and are still used in regions of low seismicity. Retrofitting of these structures is necessary because of two reasons: Firstly, observed damage after earthquakes reveals that URM construction is one of the most hazardous constructions even in the region of low seismicity; secondly, reclassification of seismic zones would require retrofitting of existing structures to comply with new guidelines for earthquake design.

Retrofitting measures require that the response of original and new structural systems as well as their interaction be considered. It is therefore important to correctly …

Utilization Of Fly Ash In Concrete, Chai Jaturapitakkul

Dissertations

Fly ash, a by-product of coal burning power plants, is produced in large quantities each year. It is commonly known that fly ash possesses pozzolanic behavior which can enhance the properties of concrete. Due to a lack of proper understanding on the formation of fly ash and its performance in concrete, the question of quality assurance has frequently been a major concern of engineers using fly ash in their construction projects. As a result, much fly ash is disposed of as waste material in landfills. Recent environmental concerns and a shortage of landfill space have rapidly escalated the disposal cost …

Competition Between Two Microbial Populations In A Sequencing Fed-Batch Reactor And Its Implications For Waste Treatment Applications, Sitaram Dikshitulu

Dissertations

Pure and simple competition between two microbial populations in a sequencing fed-batch reactor (SFBR) was studied both at the theoretical and experimental level. Competition occurred for a single chemical pollutant which could serve as the sole carbon and energy source for both competitors. A mathematical model describing the process under inhibitory kinetics (as is usually the case with hazardous and toxic substances) was derived and theoretically analyzed. The model predicts that the dynamics of a SFBR, and the kinetics of biodegradation, result in a complex set of operating regimes in which neither species, only one species, or both species survive …

Comparison Of Heart Rate With Chest Wall Vibrations, Kofi M. Arbuah

Theses

A study is done using a Microwave Interferometer as a computer-assisted non-invasive cardiopulmonary monitor. The Microwave Interferometer is used to record the mechanical vibration of the anterior chest wall by recording the velocity of the displacement of the chest wall. The objective is to first, record mechanical vibrations of the anterior chest wall at different heart rates, and second, attempt to identify the relation between heart rate and chest wall vibration.

The system uses two channels, the first signal produced by the Microwave Interferometer is a record of the velocity of the displacement of the chest wall caused by the …

Power Consumption In Single-Phase Agitated Vessels Provided With Multiple Impellers, Gwo-Ming Chang

Theses

A significant amount of data can be found in the literature on power consumption of single-impeller agitation systems. However, little and incomplete information is available for power consumption in multiple-impeller systems. Therefore, the main objective of this study is to experimentally determine the power consumed by multiple impellers in mixing vessels as a function of impeller type, impeller off-bottom clearance, impeller spacing, and agitation speed.

In this work, the power dissipated by combinations of one, two or three impellers of either identical types or different types was studied. The power drawn by each individual impeller was measured by means of …

A Review Of Acetabular Prostheses For Total Hip Arthroplasty, Jennifer Anne Citarella

Theses

This study explores the evolution, design, and clinical progress of contemporary prostheses used in orthopaedic reconstruction of the socket of the hip joint. A literature search was performed to study acetabular implants, as used in total hip arthroplasty. The history of the design of these implants is chronicled. Next, the anatomy of the acetabular region and the surgical technique performed to replace the hip socket are presented. A comprehensive discussion of the design features, rationale, and clinical results for commercially available cemented and cementless prostheses follows.

Hydroxyapatite, a bioceramic which has just recently been approved for applications in total hip …