Mechanical Engineering Commons^™

An Inverse Algorithm To Estimate Thermal Contact Resistance, Jennifer Gill

Electronic Theses and Dissertations

Thermal systems often feature composite regions that are mechanically mated. In general, there exists a significant temperature drop across the interface between such regions which may be composed of similar or different materials. The parameter characterizing this temperature drop is the thermal contact resistance, which is defined as the ratio of the temperature drop to the heat flux normal to the interface. The thermal contact resistance is due to roughness effects between mating surfaces which cause certain regions of the mating surfaces to loose contact thereby creating gaps. In these gap regions, the principal modes of heat transfer are conduction …

Micromachined Electrochemical Sensors For Hydrogen Peroxide And Chlorine Detection, Anjum Mehta

Electronic Theses and Dissertations

Hydrogen peroxide and chlorine detection is critical for many biological and environmental applications. Hydrogen peroxide plays important roles in a variety of fields including plant physiology, medical, environmental and biochemical applications. Its role in plant defense and signal transduction, diseases such as Parkinson's and Alzhemier's, industrial processes such as disinfection and wastewater treatment and biochemical enzymatic reactions is critical. Given the gamut of areas that hydrogen peroxide is a key component of; its detection assumes great importance. Similarly chlorine has long been used as a disinfectant for making drinking water safe, but excessive chlorination is an environmental and health hazard …

Performance Of Interface Elements In The Finite Element Method, Kairas Rabadi

Electronic Theses and Dissertations

The objective of this research is to assess the performance of interface elements in the finite element method. Interface elements are implemented in the finite element codes such as MSC.NASTRAN, which is used in this study. Interface elements in MSC.NASTRAN provide a tool to transition between a shell-meshed region to another shell-meshed region as well as from a shell-meshed region to a solid-meshed region. Often, in practice shell elements are layered on shell elements or on solid elements without the use of interface elements. This is potentially inaccurate arising in mismatched degrees of freedom. In the case of a shell-to-shell …

Inverse Boundary Element/Genetic Algorithm Method For Reconstruction O, Mahmood Silieti

Electronic Theses and Dissertations

A methodology is formulated for the solution of the inverse problem concerned with the reconstruction of multi-dimensional heat fluxes for film cooling applications. The motivation for this study is the characterization of complex thermal conditions in industrial applications such as those encountered in film cooled turbomachinery components. The heat conduction problem in the metal endwall/shroud is solved using the boundary element method (bem), and the inverse problem is solved using a genetic algorithm (ga). Thermal conditions are overspecified at exposed surfaces amenable to measurement, while the temperature and surface heat flux distributions are unknown at the film cooling hole/slot walls. …

Design And Development Of A Lubrication Pump For A Horizontally Mounted Air-Conditioning Compressor., Kenneth T. Gilbert

Electronic Theses and Dissertations

Horizontally mounted compressors offer the advantage of reduced height in central air-conditioning units but prove difficult to produce economically due to costs associated with the manufacture of acceptable lubrication systems for the compressors. This study develops an effective, affordable oil pump for use on a horizontal compressor. Concepts are proven through testing of prototype assemblies. Test results drive modifications for future prototypes, and prototypes demonstrating adequate performance are modified for ease of manufacture.

Research in this study proves that the most suitable design results from a modification of a rotating vane pump. The pump’s modifications enable it to pump oil …

Design Modification And Optimization Of The Interior Ballistics For An Existing Naval Gun System., Gregory Allen Dennison

Electronic Theses and Dissertations

This thesis determines the physical, chemical and thermodynamic properties of an advanced solid propellant that can be used in the proposed upgrade of the Navy's 5-inch, Mark 45 gun system to achieve a muzzle energy of 14.928x16^6 ft-lbf (20.24 mega Joules(MJ)) firing a proposed 110 pound Precision Guided Munition (PGM). This energy level corresponds to an 95% increase over the current system that uses Navy Cool, or NACO, solid propellant and a 70 pound projectile. The propellant properties were parameterized using the interior ballistics simulation code known as Interior Ballistics of High Velocity Guns - 2 (IBHVG2), version 505D. The …

Proposed Smoothing Technique To Avoid Numerical Instabilities In A Hydrodynamic Numerical Model, Thomas P. Abraham

Electronic Theses and Dissertations

Despite every effort being made to produce a completely problem-free computational model, no breakthrough has yet been made. When a numerical model is used to solve a real world problem, there is a tendency for the non-physical spurious waves to creep in. If these waves are not checked, they can lead to serious instability problems. Once these waves are removed, the model should be able to simulate physical phenomenon like circulation, separation, flow reversal in the vertical plane, mixing/transport, convection/diffusion, etc.

When a numerical mode] is made to run for a certain period of time, node-to-node oscillations may arise and …

Comparison Of Theoretical And Experimental Results Pertaining To R-Curves In Low And High Ductility Solids, Rabindra Nath Dash

Electronic Theses and Dissertations

Existing linear elastic fracture mechanics and J-integral analyses are well suited for safety assessments of high-strength, low-toughness materials. These analyses apply only to the onset of crack growth, which is usually tantamount to crack instability and structural failure in that class of materials. However, this is not the case for the low-strength, high-toughness materials in which crack instability may be preceeded [sic] by extensive stable crack growth under rising loads. Here, a substantial margin of safety may exist even when the onset of crack growth is imminent. This thesis describes research leading to a ductile fracture-mechanics methodology designed to treat …

Torsional Vibrations Of A Composite Elastic/Viscoelastic Cylindrical Shaft, Deepak Kumar Mullick

Electronic Theses and Dissertations

The primary objective of this research is to analyze the torsional vibrations of a composite bar, and the parameters associated with the vibrations. The ultimate goal in this study of vibrations is to determine their effect on the performance and safety of the system under consideration.

Long-Term Retention Of Tritium In Man, Chin-Jen Ou

Electronic Theses and Dissertations

[No abstract provided.]

Experimental Study On Viscoelastic Properties And Fracture Characteristics In Polymers, Debaranjan Mohanty

Electronic Theses and Dissertations

The research reported in this thesis is undertaken with the following objectives:
1. To determine the viscoelastic properties of polymers on creep test under constant load;
2. To determine the internal friction (loss factor) of polymers under periodic loading condition;
3. To determine the delayed time or life time on fracture of the polymer under constant loading ; and
4. To verify the relationship, theoretically predicted, between the time to fracture and the material characteristics of the polymer with experimental observations.

Experimental Investigation Of Shock Boundary Layer Interaction For Two-Dimensional And Axisymmetric Flow, A. Shawki Zahran

Electronic Theses and Dissertations

A supersonic wind-tunnel has been constructed using an 8 inch by 10 inch single stage jet vacuum ejector with a capacity of handling 0.4 lb/sec air at 4 inches Hg absolute suction pressure. A Toepler Schlieren system with 10-inch diameter parabolic mirrors has been set up for flow pattern visualization. The same apparatus was developed to obtain multi-colored views of the flow pattern. That was accomplished by placing an equilateral prism in front of the light source located at the focal plane of the first parabolic mirror. A spectrum was thus produced at the focal plane of the second parabolic …

I. Improved Ice Meltage In Ice Boxes; Ii. Temperature Control In Tents - Winter Phase., Robert Beaman Duggan

Electronic Theses and Dissertations

This thesis consists of two parts: Improved Ice Meltage in Ice Boxes; Temperature Control in Tents - Winter Phase. Improved ice meltage in the Progress refrigerator is discussed in the first part of the thesis. This portion of the work shows that satisfactory refrigerator temperatures and flat ice meltage could not be obtained simultaneously when using V-shaped ice racks, although they could be obtained separately; however, the basket-type chamber offers greater possibilities of obtaining proper temperatures and meltage characteristics. Series of tests are discussed and conclusions drawn from the results. In the second part of the thesis, a method of …

Stress Analysis By Photoelastic Methods, Herald K. Palmer

Electronic Theses and Dissertations

The object of this article is to point out how the principles of photo elasticity may be used as a basis for the analysis of stresses in machine parts. It is also to review the methods and demonstrate the procedure for the determination of the characteristics and values of stresses in the models of the parts studied.

Temperature Relationships In Tent Structures., Earl Robert Gerhard 1922-

Electronic Theses and Dissertations

No abstract provided.

The Effect Of Pigments On Oleoresinous Film Structure., Glenn Robert Eudaley 1920-

Electronic Theses and Dissertations

No abstract provided.

The Effects Of Temperature And Pressure Variation On The Process Of Cooking Foods, Benjamin M. Aldrich

Electronic Theses and Dissertations

It is generally known that water has a definite boiling temperature for each pressure to which its surface is subjected and that wet steam generated in a closed vessel maintains a definite temperature-pressure relation. Under each condition of temperature and pressure the steam contains a fixed amount of available energy stored as heat and called, "Heat Content" the value of which is usually based upon an arbitrary zero fixed a 32 degrees F., the freezing temperature of water under one atmosphere of pressure.

Discrepencies Of Theory As Against Empirical Results Of Critical Speeds Of Circular Cross Sectioned Shafting, Vern Kilpatrick

Electronic Theses and Dissertations

The scope of this thesis included computations and tests showing the first critical speeds of two shafts each 5/8" dia x 38" long one of C.R.S. and one of hard drawn brass. The purpose was to find and tabulate the discrepancies between the computed values for the critical speeds and the empirical values for critical needs.