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Articles 1 - 8 of 8

Full-Text Articles in Engineering

Development Of An Acoustic Microscope To Measure Residual Stress Via Ultrasonic Rayleigh Wave Velocity Measurements , Jane Carol Johnson Jan 1995

Development Of An Acoustic Microscope To Measure Residual Stress Via Ultrasonic Rayleigh Wave Velocity Measurements , Jane Carol Johnson

Retrospective Theses and Dissertations

High stress in a crucial instrument part can cause failure. Stress detection is one of the aims of nondestructive testing. The velocity change of acoustic waves can be used to detect stress in a material. An acoustic microscope is an instrument which induces and detects acoustic waves and in one mode of operation, is able to measure the velocity of acoustic surface waves. It does this over a very small area and is capable of high spatial resolution;One of the challenges in the measurement of stress is the achievement of high spatial resolution. Since the stress induced velocity shifts ...


Numerical Investigation Of Type Ii Non-Newtonian De/Anti-Icing Fluid Effects On Take-Off Performance For General Aviation Aircraft , Dennis James Cronin Jan 1995

Numerical Investigation Of Type Ii Non-Newtonian De/Anti-Icing Fluid Effects On Take-Off Performance For General Aviation Aircraft , Dennis James Cronin

Retrospective Theses and Dissertations

Ground icing, while preventable with glycol based freezing point depressant fluids, accounts for nearly 40-50 civil accidents a year according to one account. More viscous than Type I fluids, Type II fluids are inherently non-linear in their shear stress-rate of strain relationship having smaller relative viscosity at higher shear rates. The non-linearity makes properly scaled wind-tunnel testing difficult and computational methods are employed in this study to look at the aerodynamic effects of the deicing fluid on global performance during typical take-off maneuvers for general aviation. The method is tested on a two-dimensional NACA 0012 airfoil under typical take-off simulation ...


A Compliant Model For Estimation And Optimization Of Damping In Vibrating Structures , Thomas Jeffrey Thompson Jan 1995

A Compliant Model For Estimation And Optimization Of Damping In Vibrating Structures , Thomas Jeffrey Thompson

Retrospective Theses and Dissertations

Proposed future space missions involve large structures which must maintain precise dimensional tolerances even during dynamic maneuvers. In order to attenuate disturbances in the many modes of vibration of such a structure, active and passive vibration control are proposed. The passive control is to be achieved by placing viscous or viscoelastic members or materials within a structure in order to absorb energy. Ascertaining the best combination of locations for such treatments is difficult due to the large number of cases, each of which requires computationally expensive complex eigenvalue analyses of a finite element model to compute modal damping values;In ...


An Investigation Of The Mechanics Of Rollover For Cars And Light Trucks , Yvonne Irene Katherine Lund Jan 1995

An Investigation Of The Mechanics Of Rollover For Cars And Light Trucks , Yvonne Irene Katherine Lund

Retrospective Theses and Dissertations

Rollover of cars and light trucks in single vehicle accidents is of great interest to designers in the automotive industry and to regulators in government agencies. This thesis addresses metrics--the static stability factor, the tilt table ratio, the side pull test, and the critical sliding velocity--which are proposed measures of vehicle resistance to rollover;A notable finding is that the critical sliding velocity, CSV, is independent of the vehicle mass and roll moment of inertia and depends only on the track width and center of gravity height. Furthermore, while side pull testing and tilt table testing are mainly dependent on ...


Quo Vadis - A Framework For Intelligent Routing In Large Communication Networks , Armin Robert Mikler Jan 1995

Quo Vadis - A Framework For Intelligent Routing In Large Communication Networks , Armin Robert Mikler

Retrospective Theses and Dissertations

Modern communication networks contain hundreds if not thousands of interconnected nodes. Traffic management mechanisms must be able to support a cost-effective, responsive, flexible, robust, customer-oriented high speed communication environment while minimizing the overhead associated with management functions. Conventional traffic management mechanisms for routing and congestion control algorithms entail tremendous resource overhead in storage and update of network state information;Quo Vadis is an evolving framework for intelligent traffic management in very large communication networks. It is designed to exploit topological properties of large networks as well as their spatio-temporal dynamics to optimize multiple performance criteria through cooperation among nodes in ...


Ultrasonic Scattering From Decorated Grain Boundaries , John Mittleman Jan 1995

Ultrasonic Scattering From Decorated Grain Boundaries , John Mittleman

Retrospective Theses and Dissertations

The microstructure of polycrystalline materials is manipulated in many ways to create materials with superior engineering properties. Alloying pure materials, for example, can alter crystallographic structure to strengthen or stiffen the material, but when impurities collect along grain boundaries, the material may become embrittled. This undesirable condition is generally associated with improper heat treatment during fabrication, but it may also occur during the service life of alloys exposed to penetrating radiation or severe thermal conditions. This dissertation studies scattering from decorated grain boundaries theoretically and experimentally, and ties results for isolated scatterers to grain noise measurements on materials composed entirely ...


A Two Stage Approach For Improving Hospital Inpatient Operations Efficiency, Wen-Yen Chen Jan 1995

A Two Stage Approach For Improving Hospital Inpatient Operations Efficiency, Wen-Yen Chen

Theses and Dissertations

No abstract provided.


Experimental Analysis Of Light Vehicle Frame Structure, Terry L. Stertzel Jan 1995

Experimental Analysis Of Light Vehicle Frame Structure, Terry L. Stertzel

Theses and Dissertations

No abstract provided.