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Full-Text Articles in Engineering

Brightness Invariant Port Recognition For Robotic Aircraft Refueling, Richard A. Bennett Dec 1990

Brightness Invariant Port Recognition For Robotic Aircraft Refueling, Richard A. Bennett

Theses and Dissertations

The purpose of this thesis effort was to develop and test a brightness invariant recognition algorithm that would locate and identify the half-scale mock up of a Universal Aerial Refueling Receptacle Slipway Installation (UARRSI) aerial refueling port in different lightening conditions. This was accomplished by developing a brightness invariant port recognition of identifiable attributes of the refueling port to locate and identify the UARRSI port. Based on this approach, a brightness invariant port recognition system (BIPRS) was demonstrated which identified the refueling receptacle in different lightening conditions. The BIPRS was also invariant to orientation and size of the UARRSI port. …

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Fractal Geometry Segmentation Of High Resolution Polarimetric Synthetic Aperture Radar Data, Joseph L. Brickey Dec 1990

Fractal Geometry Segmentation Of High Resolution Polarimetric Synthetic Aperture Radar Data, Joseph L. Brickey

Theses and Dissertations

This thesis investigated the potential of fractal dimension estimation for segmenting high resolution polarimetric synthetic aperture radar. The data used during this research were collected with the Advanced Detection Technology Sensor (ADTS) developed by Massachusetts Institute of Technology Lincoln Laboratory with Defense Advanced Research Projects Agency funding. ADTS is a fully polarimetric calibrated 35 GHz SAR with one foot impulse response. A method of applying the correlation dimension algorithm developed by Grassberger and Procaccia for estimating the dimension of time series data was implemented to estimate the correlation dimension of polarimetric SAR data. A threshold sensitivity study was performed to …

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Interference Cancellation In Rf Signals Using Adaptive Array Techniques, Mark E. Brown Dec 1990

Interference Cancellation In Rf Signals Using Adaptive Array Techniques, Mark E. Brown

Theses and Dissertations

This study investigated the effectiveness of the Least Means Squared (LMS) algorithm against various types of common jammers. The LMS algorithm was implemented using the Block Oriented Systems Simulator (BOSS). The LMS algorithm was inserted at the output of a two element antenna array. The array was configured so as to have one-half wavelength spacing. A quadrature hybrid signal structure was used. The array was then tested against a barrage and sweep jammer. The barrage jammer testing consisted of varying each of the three available jammer parameters; power, frequency and angle of arrival individually. The sweep jammer testing consisted of …

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Evaluation Of An Interdigitated Gate Electrode Field-Effect Transistor For Detecting Organophosphorus Compounds, Charles P. Brothers Jr. Dec 1990

Evaluation Of An Interdigitated Gate Electrode Field-Effect Transistor For Detecting Organophosphorus Compounds, Charles P. Brothers Jr.

Theses and Dissertations

This study used integrated circuit microsensors to detect organophosphorus compounds. Chemically-sensitive thin films, copper phthalocyanine, DFPase, succinyl chloride, succinylcholine chloride, 2- naphthol(B), and L-histidine dihydrochloride,were deposited on interdigitated gate electrode (IGE) structures, with an average thickness of 2000A. Thin film electrical performance characteristics were measured for several parameters, including: DC resistance, AC impedance, time-domain, and spectral responses from 10 Hz to 1 MHz. Each microsensor contained nine IGEs; each IGE possessed an in situ field-effect transistor amplifier. After purging each sensor with filtered air, it was exposed to one or two of the following gases: diisopropyl fluorophosphate (DFP), diisopropyl methylphosphonate, …

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Angle Of Arrival Detection Through Artificial Neural Network Analysis Of Optical Fiber Intensity Patterns, Scott Thomas Dec 1990

Angle Of Arrival Detection Through Artificial Neural Network Analysis Of Optical Fiber Intensity Patterns, Scott Thomas

Theses and Dissertations

The optical sensors of United States Air Force reconnaissance vehicles, such as satellites, are subject to temporary or permanent blinding from hostile (or threat) laser radiation. By detecting and determining the angle of arrival (AOA) of the hostile radiation, the reconnaissance vehicle may be able to protect its optical sensors by taking evasive maneuvers or by shutting down the optical sensor (such as closing a shutter) until the threat has passed. In addition, the vehicle can relay information to its ground terminal allowing the intelligence community to determine the source of the hostile laser radiation. This thesis demonstrated that an …

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Establishment Of A Fabrication And Measurement Capability For Aperture-Fed Stacked Patch Microstrip Antennas At The Air Force Institute Of Technology, Christopher I. Terry Dec 1990

Establishment Of A Fabrication And Measurement Capability For Aperture-Fed Stacked Patch Microstrip Antennas At The Air Force Institute Of Technology, Christopher I. Terry

Theses and Dissertations

Much time and effort has been applied to accurately model aperture- fed stacked patch microstrip antennas at the Air Force Institute of Technology (AFIT). The results of this study provide AFIT with the capability to fabricate and measure these antennas for comparison of measured radiation characteristics to the predicted characteristics. Basic microstrip patch antenna theory is reviewed, as well as the motivation leading to the development of aperture-fed stacked patch microstrip antennas. The fabrication process used to produce the two antennas manufactured for this study is described in detail. The construction of a small anechoic chamber for pattern measurements is …

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A Procedure For Performance Assessment Of Drugs Hypothesized To Be Effective In Controlling Motion Sickness, Zainab N. Ahmed Dec 1990

A Procedure For Performance Assessment Of Drugs Hypothesized To Be Effective In Controlling Motion Sickness, Zainab N. Ahmed

Theses and Dissertations

The Air Force Institute of Technology (AFIT) is conducting research into the effectiveness of certain drugs for controlling motion sickness. If the drugs are found to be useful, they must still be proven to have no harmful effects on the operator's performance abilities. There are many methods for assessing performance effects of drugs but very little standardization exists. The Unified Tri-Services Cognitive Performance Assessment Battery (UTC-PAB) is a performance assessment method designed to be used by all military branches. This will encourage standardization of drug testing, exchange of data, and comparability of methods. Five tests were chosen from the UTC-PAB …

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Failure Mechanisms In A Quasi-Isotropic Ceramic Composite Laminate Under Tensile Fatigue Loading, Gregory D. Tracy Dec 1990

Failure Mechanisms In A Quasi-Isotropic Ceramic Composite Laminate Under Tensile Fatigue Loading, Gregory D. Tracy

Theses and Dissertations

A study was conducted to experimentally investigate the tensile fatigue damage mechanisms in a quasi-isotropic ceramic matrix composite (Corning's Nicalon/CASIII). The goals of this study were to (1) develop a grip fixture for a servo-hydraulic MTS test machine and (2) conduct a series of tests with (0/±45/90)s specimens subjected to tensile fatigue loading to study their fatigue damage growth mechanisms. Results showed that when the material was subjected to stresses below 90 MPa, it lasted over 1000000 cycles but when stressed at or above 90 MPa, it failed in less than 1000 cycles.

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Impact Damage In Curved Graphite/Epoxy Panels With Clamped Edges, Ronald B. Perry Dec 1990

Impact Damage In Curved Graphite/Epoxy Panels With Clamped Edges, Ronald B. Perry

Theses and Dissertations

Graphite/epoxy curved cylindrical panels were impacted in the center by an impact machine capable of measuring load during the test. Load, deflection and strain as functions of time were measured for six symmetric layup configurations for impact energies of 0.5 to 4.5 ft-lb. Damage was produced in all panels for certain impact energies. The extent and location of damage was determined from C-scans and optical microscopy of panel cross-sections. The cross-sections indicated that both delamination and transverse cracking contribute to internal damage. An in-house nonlinear finite element code was used to predict the panel deflections and stresses. The analysis produced …

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Estimation Of Evoked Fields Using A Time-Sequenced Adaptive Filter With The Modified P-Vector Algorithm, Jeffery A. Kepley Dec 1990

Estimation Of Evoked Fields Using A Time-Sequenced Adaptive Filter With The Modified P-Vector Algorithm, Jeffery A. Kepley

Theses and Dissertations

This thesis describes a time sequenced adaptive filter developed to estimate visually evoked fields (EF) using visually evoked potentials (EP). These non-stationary signals are buried in strong background noise. The two types of noise are magnetoencephalogram (MEG) and electronencephalogram (EEG). The filter implementation is based on the Ferrara Time Sequenced Adaptive (TSAF) using the Least-Mean-Square (LMS) algorithm and the Williams modified P-vector algorithm (mPa). This essentially results in two filters. A two stage filter structure is used in which the first stage removes the time-varying mean of the input signals. This allows the second stage to process zero-mean signals which …

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Investigation Of Strain Characteristics Of Graphite Polyetherether Ketone Using A Nonlinear Analysis And Experimental Methods, Stephen C. Gould Dec 1990

Investigation Of Strain Characteristics Of Graphite Polyetherether Ketone Using A Nonlinear Analysis And Experimental Methods, Stephen C. Gould

Theses and Dissertations

A geometric nonlinear technique is incorporated in a current finite element program. This nonlinear program allows material nonlinearity for calculating the stresses, strains and failure of composites. The improved program uses an updated Langrangian to calculate the stresses and strains. In addition, it updates the fiber orientation due to displacement in order to calculate the updated stiffness matrix. This method is valuable for large strain values. The analytical data were compared to experimental data obtained from Graphite PolyEtherEther Ketone laminates. To obtain data two geometries were used. Digitized photographs were used to measure the angle change for large strains.

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Bifurcation Analysis Of The Longitudinal Dynamics Of A Simple Powered Lifting Hypersonic Vehicle, Eric E. Fox Dec 1990

Bifurcation Analysis Of The Longitudinal Dynamics Of A Simple Powered Lifting Hypersonic Vehicle, Eric E. Fox

Theses and Dissertations

Bifurcation analysis was used to investigate the nonlinear behavior of a simple powered lifting hypersonic vehicle in circular orbit about a spherical nonrotating Earth with gradients in atmospheric density and pressure and an inverse square law for gravity. Vehicle motion is constrained to a vertical plane so only longitudinal dynamics were modeled. Bifurcation analysis was conducted using the AUTO software package. A simple five-state model with three different thrust laws was derived to describe an unaugmented vehicle whose geometric and aerodynamic characteristics follow those of the literature. A parameter representing a body flap deflection was used to conduct one set …

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Skin Friction And Heat Transfer Predictions For Hypersonic Turbulent Flow Over An Ogive-Cylinder, Richard H. Byers Dec 1990

Skin Friction And Heat Transfer Predictions For Hypersonic Turbulent Flow Over An Ogive-Cylinder, Richard H. Byers

Theses and Dissertations

The WRDC/FIMG Parabolized Navier-Stokes (PNS) Code is used to numerically predict both laminar and turbulent hypersonic flows over an ogive- cylinder body at zero angle of attack. A parametric study is conducted to determine the effects of selected code input variables on heat transfer and skin friction predictions. Comparisons are made between the PNS predictions and experimental data from the WRDC/Mach 6 High Reynolds Number Test Facility. Various problems encountered while obtaining PNS starting and marching solutions and corrective steps taken are discussed. A mesh resolution study indicates the minimum radial grid density sufficient for obtaining reasonable heat transfer results. …

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Investigation Of The High Angle Of Attack Dynamics Of The F-15b Using Bifurcation Analysis, Robert J. Mcdonnell Dec 1990

Investigation Of The High Angle Of Attack Dynamics Of The F-15b Using Bifurcation Analysis, Robert J. Mcdonnell

Theses and Dissertations

Previous studies predicted the F-15B high angle of attack and flat spin behavior using bifurcation analysis. These studies varied control surface deflections to find equilibrium and periodic solutions. The purpose of this research was to use bifurcation analysis to predict the F-15B high angle attack and flat spin behavior as a result of variable thrust, asymmetric thrust, and thrust vectoring. Using a previously developed model of the F-15, bifurcation analysis and continuation methods were used to map out the equilibrium and periodic solutions of the model as a function of the thrust parameters. A baseline bifurcation diagram, as a function …

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Damping Of Layered Beams With Mixed Boundary Conditions, Eugene T. Cottle Dec 1990

Damping Of Layered Beams With Mixed Boundary Conditions, Eugene T. Cottle

Theses and Dissertations

For many years, viscoelastic materials have been used in damping treatments to control vibration. In order to optimize a damping treatment for maximum damping, a design engineer must be able to predict frequencies of vibration of damped normal modes and loss factors as a function of the design parameters. Theoretical models of layered beams have been developed, but to date, exact solutions have assumed boundary conditions to be the same for all layers. In this thesis, equations of motion for a damped, layered beam are solved for the longitudinal displacement of both elastic layers, as well as the lateral displacement …

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Characterization Of Barium Titanate As An Optical Amplifier, George A. Vogel Dec 1990

Characterization Of Barium Titanate As An Optical Amplifier, George A. Vogel

Theses and Dissertations

The introduction of two-beam coupling in photorefractive materials has resulted in an extensive amount of research into their use as optical processing/computing elements. This dissertation develops the theoretical equations for two-beam coupling in barium titanate as an optical amplifier. One of the factors which limits the optical gain in photorefractive crystals is the loss of pump beam power to the amplification of parasitic light (beam fanning). This parasitic light is produced by light scattered from the pump beam by imperfections on both the crystal face and within the crystal. Through the analysis of signal and noise amplification as functions of …

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Specification And Equivalence Verification Of Sequential Circuits Via Vhdl, Richard L. Miller Nov 1990

Specification And Equivalence Verification Of Sequential Circuits Via Vhdl, Richard L. Miller

Theses and Dissertations

This research presents a merger of the specification and design capabilities of the Very High Speed Integrated Circuit (VHSIC) Hardware Description Language (VHDL) with a known verification method (UC Berkeley's verify software) in order to solve the design and verification problem of sequential circuits. The fruits of this research are a behavioral VHDL model for sequential circuit specification, a structural VHDL model for sequential circuit design, and a method for comparing two circuits described using these VHDL models in order to demonstrate circuit equivalence. The behavioral and structural VHDL models were developed and tested within the Intermetric's VHDL software support …

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Analysis Of Parking Orbits For A Sts External Tank In Low Earth Orbit, James E. Cross Nov 1990

Analysis Of Parking Orbits For A Sts External Tank In Low Earth Orbit, James E. Cross

Theses and Dissertations

A study was conducted of a single external tank in low earth orbit. Criteria for a parking orbit are then defined. Various orbits are then selected by varying the semi-major axis, eccentricity, and inclination. The resulting equations of motion for each of the above orbits (including atmospheric drag and a 2x0 gravity model) are numerically integrated over a time span of 90 earth days. An examination was made of the lowest initial altitudes which allowed the external tank to remain in the orbit window.

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Numerical Analysis Of Critical Inclinations About The Planet Mars, Kenneth J. Hyatt Nov 1990

Numerical Analysis Of Critical Inclinations About The Planet Mars, Kenneth J. Hyatt

Theses and Dissertations

This study investigated critical inclinations about the planet Mars. Averaged equations of motion were numerically integrated over a time span of ten Earth years for various inclinations, eccentricities, and perigee heights. Each orbit (i.e. set of initial conditions) produced a standard deviation of the variations in eccentricity (SDE) and inclination (SDI). These were calculated using a polynomial approximation to the variations. Surface plots of SDI and SDE vs the initial conditions are then examined to ascertain the critical inclinations.

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Minimum Orbits About The Planet Venus, Jeffrey J. Smith Nov 1990

Minimum Orbits About The Planet Venus, Jeffrey J. Smith

Theses and Dissertations

An investigation is conducted into low orbiting satellites around the planet Venus with drag limited lifetimes. It is possible to specify combinations of orbital elements which result in orbital lifetimes in excess of some desired value. These combinations can be assembled into Critical Curves and Critical surfaces. Critical Curves and Surfaces are defined as curves and surfaces in orbital element space above which initial element sets will result in orbits that meet or exceed lifetime requirements. A numerical method is implemented for finding these combinations, and three Critical Surfaces are examined. A decay threshold is selected for bounding satellite lifetime. …

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Dynamic Analysis Of A Combat Aircraft With Control Surface Failure, Marc Roy Nov 1990

Dynamic Analysis Of A Combat Aircraft With Control Surface Failure, Marc Roy

Theses and Dissertations

An investigation was performed to analyze the dynamic stability characteristic of an aircraft which has sustained damage to a primary control surface. The analysis was performed using the existing functional form of actual wind tunnel data taken on an F-16 model. Two control schemes are used for trimming an F-16 that has sustained damage to its rudder. The first control scheme represent the basic aircraft, while the second allowed the horizontal tail ailerons to move independently from the flaperons. The investigation was conducted for one flight condition representative of the aircraft at cruise speed. Region in α/β (angle of attack)/(sideslip …

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The Development Of The Smelting Industry In The Central Salt Lake Valley Communities Of Midvale, Murray, And Sandy Prior To 1900, Charles E. Hughes Jan 1990

The Development Of The Smelting Industry In The Central Salt Lake Valley Communities Of Midvale, Murray, And Sandy Prior To 1900, Charles E. Hughes

Theses and Dissertations

This thesis found that the three communities of Midvale, Murray, and Sandy were the center of the smelting industry in the Salt Lake Valley. These communities became the center of smelting because of their central location, the readily available water supply, and the availability of an inexpensive, efficient transportation system to ship the bullion. The smelters were surrounded by two major mountain ranges which provided a ready supply of good lead, silver, and copper ore.

The development of the smelting industry followed three separate phases or periods. The first phase was one of experimentation or period of discovery, in which …

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Exposure To Phosphine Gas During Application Of Magnesium Phosphide In Stored Product Warehouses, Mark Anthony Harrison Jan 1990

Exposure To Phosphine Gas During Application Of Magnesium Phosphide In Stored Product Warehouses, Mark Anthony Harrison

Theses and Dissertations

The use of phosphine gas requires that respiratory protection be used if exposures exceed the OSHA permissible exposure limit. As with other chemical exposures limits many of the references used to establish occupational health guidelines date back to the 1930’s and 1940’s. This is quite common and is the case with phosphine gas. Initial planning for fumigations involving magnesium phosphide requires that a hazard assessment be performed. Expected worker exposures based on previous monitoring or test data was not readily available. Many current practices and procedures for fumigations are based on recommendations from applicators who used the product in the …

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Automatic Meshing Of Free-Form Deformation Solids, Ssuta S. Hsu Apr 1989

Automatic Meshing Of Free-Form Deformation Solids, Ssuta S. Hsu

Theses and Dissertations

Development of computer models and subsequent finite element analysis, are important aspects of modern engineering design. In this process, the geometry creation and finite element analysis software are well developed; however, the process of discretizing a geometry into a proper finite element model is time consuming and tedious. The work presented here uses the free-form deformation method to create smooth solid models, and invokes a solid subdivision and transition method to generate the hexahedron finite elements. The combination of these two techniques provides an automatic mesh generator that is easy to use, creates acceptable hexahedron elements for finite element analysis, …

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Organ Doses In Routine Radiographic Procedures, Yang Han Jan 1989

Organ Doses In Routine Radiographic Procedures, Yang Han

Theses and Dissertations

There is general agreement that the extent of the risk from x-ray examination is related in some way to the radiation dose. As the dose increases, the likelihood of significant biological effects also increases. If a clear correlation between dose and effect is to be established, a convenient and reasonably accurate method of estimating patient’s absorbed doses during common radiographic examinations will be highly needed. A simple method is developed in this project to determine the two important parameters e exposure at skin entrance (ESE) and half value layer (IIVL), which is essential to get reasonably accurate estimates of absorbed …

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The Multiprocessor System With A Fairly Weighted Global Bus Arbitration Circuit, Shinobu Doi Jan 1989

The Multiprocessor System With A Fairly Weighted Global Bus Arbitration Circuit, Shinobu Doi

Theses and Dissertations

The objective of this thesis is to investigate various multiprocessor system structures and to implement and test the resultant system configuration that offers high reliability and availability, ease of expansion, ease of programming, and increased computing performances. The resultant system is a MC68000 based tightly coupled multiprocessor system with large local memories and local I/Os, arbitrated by a specially designed arbitration circuit to implement pseudo random global bus granting. Each of the computer modules is an enhanced independent uniprocessor system with channel access switches to access the global memory. In its multiprocessor mode one computer module cooperates with the other …

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Enthalpies Of Solution Of Co2 In Aqueous Methyldiethanolamine Solutions, Keith E. Merkley Jan 1987

Enthalpies Of Solution Of Co2 In Aqueous Methyldiethanolamine Solutions, Keith E. Merkley

Theses and Dissertations

The enthalpies of solution, HS, of carbon dioxide in aqueous methyldiethanolamine were measured with an isothermal flow calorimeter over wide ranges of temperature, pressure, weight percent MDEA, and loading (gmole CO2/gmole MDEA). The values of HS (kJ/gmole CO2) were found to be constant up to the saturation concentration of CO2 in the aqueous solution. In addition, experimental data showed that HS was independent of the total pressure over the solution, but linearly dependent upon both temperature and weight percent MDEA as was given by a correlation. A computer program based upon …

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Free-Form Deformations In A Constructive Solid Geometry Modeling System, Scott R. Parry Apr 1986

Free-Form Deformations In A Constructive Solid Geometry Modeling System, Scott R. Parry

Theses and Dissertations

No one will question that computers are revolutionizing the design industry. It is pointed out in [Bezier84] that before CAD/CAM, a surface was defined by tracing cross sections on a drawing and then carving these sections in wood, plastic or metal. The final model was determined by someone interpolating between the sections. This labor intensive art is being replaced by techniques of computer aided geometric design.

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A Structural Study Of Some (H6-Arene)Ml2, First Row, Group Viii, Transition Metal Complexes And Their Derivatives, Stuart Kevin Janikowski Aug 1985

A Structural Study Of Some (H6-Arene)Ml2, First Row, Group Viii, Transition Metal Complexes And Their Derivatives, Stuart Kevin Janikowski

Theses and Dissertations

The structures of five organonickel compounds were determined using x-ray diffraction techniques. This study was conducted to ascertain the relationships between the compound's structures, bonding, and chemical properties. The first structural evidence for discrete complexes containing Ni-SiX3 bonds is (h6-mesitylene)Ni(SiCl3)2 and presented. The compounds (h6-toluene)Ni(SiF3)2, crystallize in space group P21/c with Z = 2. The lattice constants at 23° C are: a = 9.056(2), b = 14.426(1), c = 13. 3 0 3 ( 2) ~, {J = 10 0. 6 9 ( 1 )0 , and a = 11. 3 5 5 ( 3) , b = 11.268(4), c …

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Flexible Engineering Software: An Integrated Workstation Approach To Finite Element Analysis, Brant Arnold Ross Apr 1985

Flexible Engineering Software: An Integrated Workstation Approach To Finite Element Analysis, Brant Arnold Ross

Theses and Dissertations

One obstacle preventing more engineers from using finite element analysis (FEA) is the difficulty of transferring data between steps in the modeling process. A Fortran computer program, Rosetta.BYU, has been developed to open data paths between finite element preprocessors (mesh generators) and finite element analysis programs, using a custom data structure. It accepts neutral data files, Version 2.0 IGES data files, and Movie.BYU files for input/output. An application of Rosetta is described. A general workstation manager program, Davinci.BYU, is reviewed that provides a support layer between the engineer and the operating system, organizes software and data files, and facilitates on-line …

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