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Articles 1 - 14 of 14

Full-Text Articles in Mechanical Engineering

Laser Cutting Of Eggshells, Palaniappa A. Molian, Jerry L. Hall, M. J. Hsu Feb 1994

Laser Cutting Of Eggshells, Palaniappa A. Molian, Jerry L. Hall, M. J. Hsu

Iowa State University Patents

Preparation of chicken embryo allantoic fluids for animal health requires opening the eggshell by cutting, drilling or punching methods. Laser cutting and drilling is used as an alternative to known processes. Both CO.sub.2 and Nd:YAG lasers are employed. A focused CO.sub.2 laser beam at a power of 200 watts in conjunction with an X-Y motion table produced 25 mm diameter "clean-cuts" in eggshells with a cutting time of 0.5 seconds per egg. The material removal mechanism was vaporization. When an axicon/lens combination is used with a CO.sub.2 laser, the cutting time ...


Advanced Fuzzy Logic Controllers And Self-Tuning Strategy , Shou-Heng Huang Jan 1994

Advanced Fuzzy Logic Controllers And Self-Tuning Strategy , Shou-Heng Huang

Retrospective Theses and Dissertations

This study has concentrated on fuzzy logic controllers from the basic aspects to an advanced self-tuning strategy. Fuzzy logic provides a very good technique for knowledge representation which makes it possible to incorporate the experience of human operators in the design of controllers;The basic concepts of fuzzy set theory, fundamental definitions of fuzzy logic, and basic structure of fuzzy logic controllers are introduced and a guideline for building the fuzzy rule-based system is developed. The rule development and adjustment strategies for fuzzy logic controllers are presented and experimentally identified. The fuzzy logic control system is analyzed on a linguistic ...


Unstructured Grid Analysis Of Three-Dimensional Conduction In Complex Geometries, John Charles Minor Jan 1994

Unstructured Grid Analysis Of Three-Dimensional Conduction In Complex Geometries, John Charles Minor

Retrospective Theses and Dissertations

No abstract provided.


The Effect Of Liquid Inundation, Vapor Shear, And Non-Condensible Gases On The Condensation Of Refrigerants Hfc-134a And Hcfc-123 , Lance Edward Rewerts Jan 1994

The Effect Of Liquid Inundation, Vapor Shear, And Non-Condensible Gases On The Condensation Of Refrigerants Hfc-134a And Hcfc-123 , Lance Edward Rewerts

Retrospective Theses and Dissertations

Shell-side condensation heat transfer data were obtained for refrigerants HFC-134a and HCFC-123, the scheduled non-CFC replacements for CFC-12 and CFC-11, respectively, using tube bundles constructed from 19.1 mm o.d. 26-fpi, 40-fpi, Turbo C-II, and GEWA SC tubes. HCFC-123 bundle data were obtained for non-condensible gas concentrations of 0.5, 1.0, 2.0, and 5.0% at four heat fluxes between 18,000 W/m2 and 34,000 W/m2. HCFC-123 vapor shear and liquid inundation studies were also conducted to simulate bundle depths of 25 tube rows at heat fluxes ranging from 17,500-31,000 W/m2 ...


Automatic Constraint-Based Synthesis Of Non-Uniform Rational B-Spline Surfaces , Philip Chacko Theruvakattil Jan 1994

Automatic Constraint-Based Synthesis Of Non-Uniform Rational B-Spline Surfaces , Philip Chacko Theruvakattil

Retrospective Theses and Dissertations

In this dissertation a technique for the synthesis of sculptured surface models subject to several constraints based on design and manufacturability requirements is presented. A design environment is specified as a collection of polyhedral models which represent components in the vicinity of the surface to be designed, or regions which the surface should avoid. Non-uniform rational B-splines (NURBS) are used for surface representation, and the control point locations are the design variables. For some problems the NURBS surface knots and/or weights are included as additional design variables. The primary functional constraint is a proximity metric which induces the surface ...


Shell-Side Condensation Of Hfc-134a And Hcfc-123 On Enhanced-Tube Bundles , Joseph B. Huber Jan 1994

Shell-Side Condensation Of Hfc-134a And Hcfc-123 On Enhanced-Tube Bundles , Joseph B. Huber

Retrospective Theses and Dissertations

For the past five decades, CFCs (chlorofluorocarbons) have been some of the primary working fluids used in vapor-compression refrigeration devices. In recent years, CFCs (such as CFC-12 and CFC-11) have been found to destroy the Earth's protective ozone layer, and current mandates require that all new refrigeration equipment produced after 1996 must use an ozone-safe refrigerant. Currently, HFC-134a is targeted as the replacement for CFC-12, and HCFC-123 is targeted as a near-term replacement for CFC-11. The purpose of the present study was to obtain experimental performance data for the shell-side condensation of HFC-134a and HCFC-123 on enhanced tube surfaces ...


Dynamics And Controls For Robot Manipulators With Open And Closed Kinematic Chain Mechanisms , Sam-Sang You Jan 1994

Dynamics And Controls For Robot Manipulators With Open And Closed Kinematic Chain Mechanisms , Sam-Sang You

Retrospective Theses and Dissertations

This dissertation deals with dynamics and controls for robot manipulators with open and closed kinematic chain mechanisms;Part I of this dissertation considers the problem of designing a class of robust algorithms for the trajectory tracking control of unconstrained single robot manipulator. The general control structure consists of two parts: The nominal control laws are first introduced to stabilize the system in the absence of uncertainties, then a class of robust nonlinear control laws are adopted to compensate for both the structured uncertainties and the unstructured uncertainties by using deterministic approach. The possible upper bounds of uncertainties are assumed to ...


Numerical Evaluation Of Corona Discharge As A Means Of Boundary Layer Control And Drag Reduction , Samir Hamza El-Khabiry Jan 1994

Numerical Evaluation Of Corona Discharge As A Means Of Boundary Layer Control And Drag Reduction , Samir Hamza El-Khabiry

Retrospective Theses and Dissertations

Problems of viscous drag reduction and boundary layer control have been and continue to be objectives of research for their economic impact and the enhancement of the flight characteristics of flying vehicles. Corona discharge is a new technique in this regard;The study of this technique requires consideration of the electrostatics and fluid mechanics. In order to effectively evaluate the technique with minimum complications, the geometry chosen was a dc positive corona discharge on a flat plate of zero thickness at zero angle of attack with the fluid flow as steady state, two-dimensional, incompressible viscous one. Five coupled partial differential ...


An Experimental Evaluation Of The Miscibility Characteristics Of Ten Different Non-Cfc Refrigerants With Fourteen Different Lubricants , Steven Charles Zoz Jan 1994

An Experimental Evaluation Of The Miscibility Characteristics Of Ten Different Non-Cfc Refrigerants With Fourteen Different Lubricants , Steven Charles Zoz

Retrospective Theses and Dissertations

Miscibility data are needed to determine the suitability of refrigerant/lubricant combinations for use in a refrigeration system. Refrigeration systems require a miscible refrigerant/lubricant mixture for proper compressor lubrication, for proper lubricant return to the compressor, and for maximum heat transfer performance in the evaporator. Thermodynamic analysis of binary mixtures provides methods for determining the miscibility characteristics of refrigerant/lubricant mixtures, but experimental solubility data (pressure-temperature-composition) must first be obtained. Therefore, miscibility data are more conveniently obtained from direct experimental evaluation as was performed in this study;A new method for rapidly obtaining refrigerant/lubricant miscibility data has been ...


Heat Transfer And Fluid Flow In Spray Evaporators With Application To Reducing Refrigerant Inventory , Shane Alan Moeykens Jan 1994

Heat Transfer And Fluid Flow In Spray Evaporators With Application To Reducing Refrigerant Inventory , Shane Alan Moeykens

Retrospective Theses and Dissertations

As the phase-out of chlorofluorocarbons (CFC's) approaches, there is a current need for the development of new vapor compression chillers which can operate with non-CFC refrigerants while still maintaining high operating efficiencies. Redesign of the traditional flooded evaporator used in refrigeration chillers so as to incorporate a spray evaporation capability offers both a potential for increased heat transfer performance and a reduction in refrigerant inventory for a given chiller capacity relative to that found with existing industrial units;This study is an evaluation of the spray evaporation heat transfer performance of refrigerants HFC-134a, HCFC-22, and HCFC-123 with commercially available ...


An Experimental Evaluation Of Capillary Tube-Suction Line Heat Exchanger Performance With Alternative Refrigerants Hfc-134a And Hfc-152a , Robert Rudolph Bittle Jan 1994

An Experimental Evaluation Of Capillary Tube-Suction Line Heat Exchanger Performance With Alternative Refrigerants Hfc-134a And Hfc-152a , Robert Rudolph Bittle

Retrospective Theses and Dissertations

Worldwide environmental concerns have resulted in mandates that CFC refrigerants be replaced with alternative refrigerants. The most common refrigerant used in household refrigerators is CFC-12, and alternative refrigerants HFC-134a and HFC-152a are potential replacements;The capillary tube is the predominant expansion device found in household refrigerators. It is usually soldered to the suction line for three to five feet of length, thus, creating a simple counter-flow heat exchanger. Heat exchanger performance is characterized by both the refrigerant mass flow rate and a heat transfer effect, commonly referred to as effective subcooling;Capillary tube-suction line heat exchanger performance was experimentally evaluated ...


A New Methodology For The Determination Of Transport Properties Of Refrigerants , Jian-Yuan Lin Jan 1994

A New Methodology For The Determination Of Transport Properties Of Refrigerants , Jian-Yuan Lin

Retrospective Theses and Dissertations

R-22, R-502, and R-114 have been widely used as working fluids in refrigeration units for the past several decades. However, all of the above refrigerants have been classified as phase-out refrigerants because they are detrimental to the ozone layer. Presently, one of the leading candidates to replace R-114 is HFC-236ea (hexafluoropropane), while several potential refrigerant mixtures are being considered to replace R-22 and R-502. These refrigerant mixtures to replace R-22 and R-502 are primarily composed of R-32, R-125, R-134a, and R-143a. Two ternary blends reported to have potential to replace R-22 and R-502 are blend A: R-32 (23%)/R-125 (25 ...


Simulation Of Three-Dimensional Incompressible Flows With Free-Surfaces Including Fluid-Structure Interaction And Microgravity Flows , Sethuraman Babu Jan 1994

Simulation Of Three-Dimensional Incompressible Flows With Free-Surfaces Including Fluid-Structure Interaction And Microgravity Flows , Sethuraman Babu

Retrospective Theses and Dissertations

This dissertation describes the evolution of a method for accurately predicting unsteady, three-dimensional, viscous flows with free-surfaces. The special feature of this study is a time-accurate and divergence-free procedure for the computation of the free-surface motion. The method attempts to achieve second order temporal resolution of the free-surface motion through an iterative procedure. The momentum equations are also discretized using a time centered implicit differencing using information from two time levels. The formulation uses a surface-fitting approach which forces the free-surface to coincide with one boundary of the computational domain and solves the three-dimensional incompressible Navier-Stokes equations in primitive variable ...


Emissions And Combustion Of Fatty Acid Esters Of Soybean Oil In A Diesel Engine, Yu Zhang Jan 1994

Emissions And Combustion Of Fatty Acid Esters Of Soybean Oil In A Diesel Engine, Yu Zhang

Retrospective Theses and Dissertations

No abstract provided.