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Articles 1 - 28 of 28

Full-Text Articles in Mechanical Engineering

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 ...


Modeling Joint Kinetics In The Tkatchev Release Move , Martha Nichols-Ketchum Jan 1994

Modeling Joint Kinetics In The Tkatchev Release Move , Martha Nichols-Ketchum

Retrospective Theses and Dissertations

This study developed a three-dimensional computer simulation model of the Tkatchev release move on the men's horizontal bar. The model used the Hanavan human body model and the inverse dynamics approach to predict resultant forces and torques at the joints during performance. The model was used to determine aspects of the performance that contribute to the risk of injury and to determine strength and flexibility requirements for the skill;This study was done in two parts. In Part 1, kinetic parameters were calculated from actual performances of Tkatchevs. Two college-level male gymnasts each performed 9-10 Tkatchevs during a single ...


Dynamics Of A Power Line When Supported By A Compliant Energy Absorber , Elias Bitencourt Teodoro Jan 1994

Dynamics Of A Power Line When Supported By A Compliant Energy Absorber , Elias Bitencourt Teodoro

Retrospective Theses and Dissertations

Power lines are subjected to complex aerodynamic forces that may cause galloping. The galloping phenomenon is highly complex because of the nonlinear, geometric-dependent, time-varying aerodynamic loads and the resulting amplitudes of vibration, which may cause interactions between various vibration modes and also between adjacent spans and their support hardware. It is generally agreed that cable galloping is the result of the aerodynamic instability of ice-coated cables. This instability can be defined in terms of measurable aerodynamic properties of the airfoils and the characteristics of the mechanical system. Galloping oscillations can cause interphase clashing, which may lead to flashovers that result ...


Seismic Modeling Of Structures With Steel Deck Reinforced Concrete Diaphragms , Francisco Santiago Yeomans Reyna Jan 1994

Seismic Modeling Of Structures With Steel Deck Reinforced Concrete Diaphragms , Francisco Santiago Yeomans Reyna

Retrospective Theses and Dissertations

Analytical work on the response prediction of a hysteretic model for steel deck reinforced concrete (SDRC) diaphragms subjected to seismic loads was performed as part of the overall research diaphragm program conducted at Iowa State University (ISU). This work focused on the development of a hysteretic model with nonlinear, inelastic, degrading and pinching capabilities to predict the in-plane shear response of SDRC diaphragms under earthquake loads, and the definition of an analytical modeling scheme to include the effects of the diaphragm flexibility in the analysis of frame-wall structures;Predictive equations describing the hysteretic characteristics of the model were developed. Developed ...


Use Of Virtual Reality In Off-Line Robot Programming, Darren Scott Knapp Jan 1994

Use Of Virtual Reality In Off-Line Robot Programming, Darren Scott Knapp

Retrospective Theses and Dissertations

http://www.worldcat.org/oclc/30752047


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 ...


A Study On Air Flow And Odor Emission Rate From A Simplified Manure Storage Tank , Qianbao Liu Jan 1994

A Study On Air Flow And Odor Emission Rate From A Simplified Manure Storage Tank , Qianbao Liu

Retrospective Theses and Dissertations

This study presents a numerical and experimental evaluation of air flow and odor emission rate from an open manure storage tank. The concentration at the manure surface, the tank dimensions, and wind speed were used to calculate air flow and the emission rate;The three-dimensional air flow in the open tank was divided into four segments and each segment was treated as two-dimensional. The SIMPLER algorithm developed by Patankar and a two layer turbulence model were used in the numerical simulation with a grid of 152 x 139;The predicted emission rate agreed with the field measurement results found in ...


An Interacting Boundary Layer Method For Unsteady Compressible Flows , Robert Edwin Bartels Jan 1994

An Interacting Boundary Layer Method For Unsteady Compressible Flows , Robert Edwin Bartels

Retrospective Theses and Dissertations

A time accurate compressible interactive boundary layer procedure for airfoils using the quasi-simultaneous method of Veldman is developed. It couples the high frequency transonic small disturbance equation with the complete set of unsteady compressible boundary equations in Levy-Lees variable form, using a pseudo-time derivative of displacement thickness for enhanced stability. Included is a simple procedure for time accurately updating the viscous wake location. The basis of the interaction is an extension of the asymptotic matching condition of Davis for unsteady compressible interaction. This analysis identifies several possible unsteady transonic separation structures and highlights the importance of the pseudo-time derivative in ...


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 ...


Design Of A Wing Section In Ground Effect: Application To High Speed Ground Transportation , Christoph Hiemcke Jan 1994

Design Of A Wing Section In Ground Effect: Application To High Speed Ground Transportation , Christoph Hiemcke

Retrospective Theses and Dissertations

This dissertation attempts to fully explain the aerodynamic ground effect phenomenon, which occurs when a wing flies over a nearby plane. The long-term motivation is to determine the feasibility of a train that achieves aerodynamic levitation above a flat guideway. Such a train would rely exclusively on lifting surfaces, rather than on steel wheels, lifting fans, or magnetic fields.;As a first step in the study of an aerodynamically suspended train, a wing section must be designed. This dissertation focuses on the preliminary design and the experimental investigation of a two-dimensional airfoil in ground effect. For application to high-speed ground ...


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 ...


Modelling And Evaluation Of A Cistern-Based Ground-Coupled Heat Pump: Its Implications In Reducing Energy In A Commercial Swine Operation , James D. Leary Jan 1994

Modelling And Evaluation Of A Cistern-Based Ground-Coupled Heat Pump: Its Implications In Reducing Energy In A Commercial Swine Operation , James D. Leary

Retrospective Theses and Dissertations

This research details the analysis of a ground-coupled heat pump system which utilizes a 20,000 gallon well-water storage tank as a source of heating and cooling. It addresses the feasibility of such a system and discusses the system in terms of energy efficiency--first law conservation analysis. The potential use of this type of system for the control of sensitive thermal environments involving swine is also evaluated;The goal of this research was to investigate ISU's SNMRC heat pump system. Specific objectives were: (1) To evaluate the system in terms of heat exchanger and heat pump efficiencies. (2) To ...


Dynamics And Vibrations Of Magnetostrictive Transducers , David L. Hall Jan 1994

Dynamics And Vibrations Of Magnetostrictive Transducers , David L. Hall

Retrospective Theses and Dissertations

An engineering investigation into the dynamics and vibrations of magnetostrictive transducers is conducted. The transducers are examined from a linear systems perspective. The system input is electric current. The system output is displacement. A comparison is made between the classic low-signal linear transduction equations for the material and those for the electromechanical transducer containing the material. A magnetomechanical model is derived assuming the magnetostrictive rod behaves as a linear spring. The model is an expression for the complex valued, frequency, coupling, and load dependant magnetic permeability of the magnetostrictive material within the transducer. One-dimensional analytical constant parameter linear electromagnetic models ...


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 ...


Efficient Inversion Of Fourier And Laplace Domain Boundary Element Solutions For Elastodynamic Scattering , Joel Kevin Ness Jan 1994

Efficient Inversion Of Fourier And Laplace Domain Boundary Element Solutions For Elastodynamic Scattering , Joel Kevin Ness

Retrospective Theses and Dissertations

In ultrasonic nondestructive testing, the actual time domain signature of a scattered wave due to a pulsed input is the common observable (via oscilloscope) quantity. Numerically simulated solutions are thus desirable in the time domain. These can be obtained by working directly in the time domain or by inversions of integral transform solutions in the frequency (Fourier) or Laplace domains. Direct time solutions are suitable for short times but generally deteriorate for longer times. Alternately, the transform techniques generally require solutions over a wide spectrum in the transform variable to provide accurate inversions back to the time domain. However, without ...


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 ...


Structural Wave Propagation And Sound Radiation Study Through Time And Spatial Processing , Ruey-Chang Wei Jan 1994

Structural Wave Propagation And Sound Radiation Study Through Time And Spatial Processing , Ruey-Chang Wei

Retrospective Theses and Dissertations

This work explores new usages of experimental and analysis tools to study the relationship between the wave propagation and sound radiation in a structure with inhomogeneities. The focus of the research is to develop and test new and merged techniques. The analysis tools used in the research include: time domain analysis, k-space analysis, and wave speed tracking. With the time domain analysis, one can study the response of any synthetic excitation with only one set of experimental data. The k-space analysis provides insight into locating areas on a vibrating structure that radiate sound to the acoustic farfield. The wave speed ...


Active Noise Control In A Three-Dimensional Space , Jihe Yang Jan 1994

Active Noise Control In A Three-Dimensional Space , Jihe Yang

Retrospective Theses and Dissertations

In this research, a new approach is presented for optimizing the performance of active noise control in three-dimensional space. The work focuses on the critical role of determining the locations for secondary sources in active noise suppression. A systematic technique is proposed for estimating optimal locations of secondary sources on the boundary of a three-dimensional domain for both local and global active control of harmonic sound fields. The theoretical foundation of this work is Huygen's principle. The indirect boundary element method (IBEM) which is a numerical implementation of Huygen's principle is employed as a basis for the numerical ...


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 ...


Measurement Of Elastic Moduli Of Porous Sic/Sic Ceramic Matrix Composites Using Ultrasonics, Vikram Saini Jan 1994

Measurement Of Elastic Moduli Of Porous Sic/Sic Ceramic Matrix Composites Using Ultrasonics, Vikram Saini

Retrospective Theses and Dissertations

Forced Chemical Vapor Infiltration (FCVI) method was used in fabricating the Nicalon™/Silicon Carbide composites. Both through-thickness and In-plane (fiber fabric plane) moduli were determined using ultrasonic techniques. The through-thickness moduli were found to be much less than the inplane moduli. Both in-plane and through-thickness moduli were significantly decreased with an increased porosity. The experimental results for the moduli were found to be in good agreement with a theoretical model.


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.


Spline Network Modeling And Fault Classification Of A Heating Ventilation And Air-Conditioning System , Mathew Scaria Chackalackal Jan 1994

Spline Network Modeling And Fault Classification Of A Heating Ventilation And Air-Conditioning System , Mathew Scaria Chackalackal

Retrospective Theses and Dissertations

A spline network, that is an alternative to artificial neural networks, is introduced in this dissertation. This network has an input layer, a single hidden layer, and an output layer. Spline basis functions, with small support, are used as the activation functions. The network is used to model the steady state operation of a complex Heating Ventilation and Air-conditioning (HVAC) system. Real data was used to train the spline network. A neural network was also trained on the same set of data. Based on the training process, it is possible to conclude that when compared to artificial neural networks, the ...


Characterization And Analysis Of Viscoelastically Loaded Thin Film Piezoelectric Resonators Incorporated In An Oscillator Microsensing System , Ronald Patrick O'Toole Jan 1994

Characterization And Analysis Of Viscoelastically Loaded Thin Film Piezoelectric Resonators Incorporated In An Oscillator Microsensing System , Ronald Patrick O'Toole

Retrospective Theses and Dissertations

In the recent advancement of piezoelectric resonator technology, there has been a large growth in the application of these devices for chemical sensing. These sensors operate by detecting changes in their environment which perturb the electrical - acoustic operation and in turn can be harnessed by means of supporting electronics and signal processing to monitor various processes. Examples include remote environmental monitoring, chemical process control, and commercial gas phase detectors. In this dissertation, the chemical sensing theory and properties of piezoelectric resonators such as the bulk-acoustic wave thin-film resonator (TFR) and the quartz crystal microbalance (QCM) are developed. This analysis concentrates ...