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Articles 4711 - 4740 of 4850

Full-Text Articles in Engineering

Discussion Of The Representation Of Intercrystalline Misorientation In Cubic Materials, Brent L. Adams, Hans Grimmer, Junwu Zhao Jan 1990

Discussion Of The Representation Of Intercrystalline Misorientation In Cubic Materials, Brent L. Adams, Hans Grimmer, Junwu Zhao

Faculty Publications

BLA and JZ acknowledge the support of the Office of Basic Energy Science of the US Department of Energy under grant No. DE-FG02-88ER45355. Help from Stuart Wright with the figures is gratefully acknowledged. Salient features of various parameterizations of cubic-cubic misorientation are discussed. It is proposed that the quaternion representation of rotations, as a pair of antipodal points on the surface of a four-dimensional sphere, encompasses the most desirable properties of other proposed representations, viz rectilinearity, a closed form for the composition of successive rotations, and an equivalence between the Euclidean measure on its parameter space and the invariant measure …

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Molecular Dynamics Simulation Of Real-Fluid Mutual Diffusion Coefficients With The Lennard-Jones Potential Model, Richard L. Rowley, J. M. Stoker Sep 1989

Molecular Dynamics Simulation Of Real-Fluid Mutual Diffusion Coefficients With The Lennard-Jones Potential Model, Richard L. Rowley, J. M. Stoker

Faculty Publications

Mutual diffusion coefficients for selected alkanes in carbon tetrachloride were calculated using molecular dynamics and Lennard-Jones (LJ) potentials. Use of effective spherical LJ parameters is desirable when possible for two reasons: (i) computer time is saved due to the simplicity of the model and (ii) the number of parameters in the model is kept to a minimum. Results of this study indicate that mutual diffusivity is particularly sensitive to the molecular size cross parameter, σ12, and that the commonly used Lorentz–Berthelot rules are inadequate for mixtures in which the component structures differ significantly. Good agreement between simulated and experimental mutual …

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Development, Simulation, And Validation Of A Highly Nonlinear Hydraulic Servosystem Model, Tim W. Mclain, E K. Iversen, C C. Davis, S C. Jacobsen Jun 1989

Development, Simulation, And Validation Of A Highly Nonlinear Hydraulic Servosystem Model, Tim W. Mclain, E K. Iversen, C C. Davis, S C. Jacobsen

Faculty Publications

A highly accurate and predictive dynamic model of an electrohydraulic actuation system has been developed and verified. The accuracy of the model can be attributed to the inclusion of nonlinear representations of many system elements including hysteresis and saturation effects, orifice areas, piston damping, and flow forces. This level of accuracy makes the model a potentially valuable tool in the analysis and design of electrohydraulic actuation systems.

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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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Design Of A Multiple Degree Of Freedom, Force Reflective Hand Master/Slave With A High Mobility Wrist, Tim Mclain, S C. Jacobsen, E K. Iversen, C C. Davis, D M. Potter Mar 1989

Design Of A Multiple Degree Of Freedom, Force Reflective Hand Master/Slave With A High Mobility Wrist, Tim Mclain, S C. Jacobsen, E K. Iversen, C C. Davis, D M. Potter

Faculty Publications

The Center for Engineering Design (CED) at the University of Utah has developed a force reflective, teleoperated multiple degree of freedom hand and high mobility wrist. This hand/wrist teleoperation system is targeted to perform dexterous manipulation and assembly tasks in an effort to approach the capabilities of a human. A first-stage prototype of this hand/wrist master/slave system, which is scheduled for laboratory demonstration in February of 1989, has nine actuated degrees of freedom in both the hand master and hand slave. This paper discusses elements of the design of this hand/wrist master and slave with particular emphasis on servo system …

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On The Use Of A Modified Square-Well Model For Prediction And Correlation Of Thermal Diffusion Factors In Binary Liquid Mixtures, Richard L. Rowley, S. C. Yi Dec 1987

On The Use Of A Modified Square-Well Model For Prediction And Correlation Of Thermal Diffusion Factors In Binary Liquid Mixtures, Richard L. Rowley, S. C. Yi

Faculty Publications

Recently reported thermal diffusion factors obtained from heats of transport have been used to test the ability of existing theories to predict thermal diffusivities using model parameters regressed from pure component transport data. None of the theories tested were able to provide even qualitative agreement with experiment. However, predictions using a square-well Enskog theory, modified here for consistency with normal experimental definitions, were found to be approximately correct using pure-component square-well parameters regressed from viscosity and thermal conductivity and an assumed mixing rule for cross terms. Predicted values are very sensitive to the energy mixing rule, and correlation of experimental …

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Heats Of Transport From Diffusion Thermoeffect Measurements On Binary Liquid Mixtures Of Carbon Tetrachloride With Benzene, Toluene, 2-Propanone, N-Hexane, And N-Octane, Richard L. Rowley, S. C. Yi Dec 1987

Heats Of Transport From Diffusion Thermoeffect Measurements On Binary Liquid Mixtures Of Carbon Tetrachloride With Benzene, Toluene, 2-Propanone, N-Hexane, And N-Octane, Richard L. Rowley, S. C. Yi

Faculty Publications

Measurements of heats of transport are reported for binary liquid mixtures containing carbon tetrachloride and benzene, toluene, 2-propanone, n-hexane, or n-octane at 298 K and ambient pressure. Additionally, measurements were made at 308 K for carbon tetrachloride with benzene, toluene, and 2-propanone. The corresponding heat-mass Onsager coefficients are also reported, from which thermal diffusion ratios have been calculated based on Onsager reciprocity. These data will be used in a companion paper to report a modified Enskog method for correlation and prediction of heats of transport.

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Definition Of An Asymmetric Domain For Intercrystalline Misorientation In Cubic Materials In The Space Of Euler Angles, Brent L. Adams, Junwu Zhao Dec 1987

Definition Of An Asymmetric Domain For Intercrystalline Misorientation In Cubic Materials In The Space Of Euler Angles, Brent L. Adams, Junwu Zhao

Faculty Publications

The authors wish to acknowledge the support of the United States Department of Energy, Office of Basic Energy Sciences, under grant No. DE-FG02-85ER45203. Critical review by Professor Dorian Hatch of the Physics Department at Brigham Young University is gratefully acknowledged. A new asymmetric domain for intercrystalline misorientation is defined in the space of Euler angles for materials exhibiting cubic (Oh point-group) lattice symmetry. The invariant measure for this new domain is nearly constant; this is in significant contrast to the previous domain defined by MacKenzie [Biornetrika (1958), 45, 229-240]. Distribution functions in the misorientation can now be represented with greater …

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Decision-Directed Multivariate Empirical Bayes Classification With Nonstationary Priors, Wynn C. Stirling, A. Lee Swindlehurst Sep 1987

Decision-Directed Multivariate Empirical Bayes Classification With Nonstationary Priors, Wynn C. Stirling, A. Lee Swindlehurst

Faculty Publications

A decision-directed learning strategy is presented to recursively estimate (i.e., track) the time-varying a priori distribution for a multivariate empirical Bayes adaptive classification rule. The problem is formulated by modeling the prior distribution as a finite-state vector Markov chain and using past decisions to estimate the time evolution of the state of this chain. The solution is obtained by implementing an exact recursive nonlinear estimator for the rate vector of a multivariate discrete-time point process representing the decisions. This estimator obtains the Doob decomposition of the decision process with respect to the a-field generated by all past decisions and corresponds …

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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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Simultaneous System Identification And Decision-Directed Detection And Estimation Of Jump Inputs To Linear Systems, Wynn C. Stirling Jan 1987

Simultaneous System Identification And Decision-Directed Detection And Estimation Of Jump Inputs To Linear Systems, Wynn C. Stirling

Faculty Publications

A decision-directed approach is presented for analyzing linear systems with unknown jump inputs. The system model parameters are estimated using a Kalman filter, and an empirical Bayes detection procedure is introduced to set the detector parameters, resulting in a decision-directed generalized likelihood ratio test coupled with recursive system parameter estimation. Monte Carlo results are presented to validate the performance of the algorithm.

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Editing Templates: A User Interface Generation Tool, Dan R. Olsen Jr. Nov 1986

Editing Templates: A User Interface Generation Tool, Dan R. Olsen Jr.

Faculty Publications

This article discusses a basic architecture for a user interface management system and the problem of updating a display in response to interactive commands. The basic architecture is then extended to include basic editing and browsing processes on arbitrary data structures. Editing templates are presented as a technique embodying the entire manipulation process for a particular data structure/data display combination. In conjuction with the user interface management system, Such templates are able to automatically provide a majority of the code required in an interactive applicaton.

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Heats Of Transport From The Diffusion Thermoeffect In Binary Liquid Mixtures Of Toluene, Chlorobenzene, And Bromobenzene, Richard L. Rowley, M. D. Hall Sep 1986

Heats Of Transport From The Diffusion Thermoeffect In Binary Liquid Mixtures Of Toluene, Chlorobenzene, And Bromobenzene, Richard L. Rowley, M. D. Hall

Faculty Publications

Measurements of heats of transport in binary liquid mixtures of toluene, chlorobenzene, and bromobenzene utilizing the diffusion thermoeffect, or Dufour effect, are reported at 298 and 308 K. The corresponding heat-mass Onsager doefficients are also reported, from which thermal diffusion ratios have been calculated based on Onsager reciprocity. The resultant binary thermal diffusion ratios have been correlated as a function of composition in an attempt to study the relationship between values in binary and ternary mixtures. It was found that the single independent binary values can be used to estimate the two independent thermal diffusion ratios previously reported in toluene …

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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 Theoretical Basis For Practical Amplifier Design Using Cascaded Operational Amplifiers, David J. Comer Aug 1985

A Theoretical Basis For Practical Amplifier Design Using Cascaded Operational Amplifiers, David J. Comer

Faculty Publications

A procedure is developed for the design of amplifiers to meet specified gain and bandwidth figures. The number of required operational amplifier stages is minimised. A figure of merit is introduced to determine if a particular operational amplifier can be used to satisfy a given set of specifications.

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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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Application Of Combined Jointed Media And Discrete Slip Plane Characteristics To Subsidence Predictions, David W. Basinger Dec 1984

Application Of Combined Jointed Media And Discrete Slip Plane Characteristics To Subsidence Predictions, David W. Basinger

Theses and Dissertations

This thesis presents an application of a numerical formulation incorporating the effects of joints, cracks, and fractures to a soil subsidence predictions problem, and the extension of that formulation to combined discrete slip planes and jointed media continua formulations. The results obtained are compared to each other and to a physical centrifuge simulation performed previously on the same problem.

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Two-Dimensional Computer Modeling Of Joints And Fractures In Continua, Royd R. Nelson Dec 1983

Two-Dimensional Computer Modeling Of Joints And Fractures In Continua, Royd R. Nelson

Theses and Dissertations

This thesis presents a numerical formulation which incorporates the effects of joints, cracks, and fractures into a mathematical mode used to in an existing finite element code. Two separate crack definitions were incorporated, one involving a discrete crack model, and the other a continuum approach defining a new material with regularly spaced joints. Several examples are also presented demonstrating the use of this capability.

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Development Of A Computer-Aided Graphics Capability To Display Field Test Data, L. Allen Adams Aug 1983

Development Of A Computer-Aided Graphics Capability To Display Field Test Data, L. Allen Adams

Theses and Dissertations

This thesis develops an interactive computer-aided graphics package for the display of experimental and field test data. EXPERT was developed to be used in conjunction with MOVIE.BYU and DISSPLA, utilizing a bivariate interpolation scheme to create a full field of data using the "sparse" field data as pivotal points. The usefulness and practicality of the program is demonstrated by graphically displaying the data from the Air Force Weapons Laboratory's CHEAT test.

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Development Of A Computer-Aided Analysis Package For Linear Elastic Fracture Mechanics, William E. Warkentin Apr 1983

Development Of A Computer-Aided Analysis Package For Linear Elastic Fracture Mechanics, William E. Warkentin

Theses and Dissertations

This thesis develops an interactive computer-aided analysis package for solving linear elastic fracture mechanics problems. CHILES 2 (an existing finite element fracture mechanics program) was modified to be interactive. The modified program is named CHILES.BYU and is used in conjunction with QMESH.BYU and MOVIE.BYU to form the total software package. An analysis of glass ceramics and glass ceramic/metal interfaces was performed demonstrating the capabilities of the package. This study demonstrates the usefulness of an interactive package of computer programs to allow an engineer to rapidly investigate different crack configurations.

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Scrubs.Byu A Two Dimensional Finite Element Package For Continuum Analysis Using Quadratic Isoparametric Elements, Michael Glenn Long Apr 1983

Scrubs.Byu A Two Dimensional Finite Element Package For Continuum Analysis Using Quadratic Isoparametric Elements, Michael Glenn Long

Theses and Dissertations

This thesis develops a two dimensional, axisymmetric finite element package for solving continuum problems including rubbleization subsidence and nonlinear fracture mechanics. This package includes both a user friendly preprocessor, PRESCRUBS.BYU, and a versatile analysis code SCRUBS.BYU. PRESCRUBS.BYU systematically creates the data file necessary to run SCRUBS.BYU. SCRUBS.BYU provides many options of nonlinear static analysis using either linear or quadratic isoparametric finite elements. Sample problems are presented that demonstrate the capabilities of this package.

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The Diffusion Thermoeffect In Ternary, Nonelectrolyte Liquid Mixtures, Richard L. Rowley, Gerald Platt, Tevin Vongvanich Aug 1982

The Diffusion Thermoeffect In Ternary, Nonelectrolyte Liquid Mixtures, Richard L. Rowley, Gerald Platt, Tevin Vongvanich

Faculty Publications

Expressions for that portion of the heat flux which is due to composition gradients in multicomponent nonelectrolyte liquid mixtures have been formulated in terms of heats of transport. The resultant thermal energy equation in combination with component mass balance equations constitute coupled partial differential equations descriptive of the diffusion thermoeffect in liquid mixtures. These equations were solved with a double perturbation technique subject to initial and boundary conditions consistent with experimental design conditions considered appropriate for successful measurement of multicomponent heats of transport. Based on the adiabatic type cell, the expected temperature response, dependent on cell variables, experimental conditions, and …

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Diffusion Thermoeffect Measurements Of Heats Of Transport In Ternary Liquid Toluene Chlorobenzene Bromobenzene Mixtures At 25°C And 3°C, Richard L. Rowley, Gerald Platt, Tevin Vongvanich Aug 1982

Diffusion Thermoeffect Measurements Of Heats Of Transport In Ternary Liquid Toluene Chlorobenzene Bromobenzene Mixtures At 25°C And 3°C, Richard L. Rowley, Gerald Platt, Tevin Vongvanich

Faculty Publications

Heats of transport in ternary nonelectrolyte liquid mixtures have been directly measured for the first time. Diffusion thermoeffect measurements have been made for ternary mixtures of toluene-chlorobenzene-bromobenzene at 25 degrees and 35 degrees C. A new boundary sharpening technique was used in addition to a liquid gate withdrawal method. Both techniques yield consistent, accurate values of the heat of transport, but the new cell provides versatility in allowable densities and compositions of the initial phases. Heats of transport were obtained by nonlinear least-squares fitting of calculated to experimental temperature differences measured at positions symmetric about the initial diffusional interface. The …

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A Unique Microprocessor Instruction Set, D. A. Fairclough May 1982

A Unique Microprocessor Instruction Set, D. A. Fairclough

Faculty Publications

New instruction sets have been based on traditather than on the application of scientific method. Here, the latter has yielded a simple, optimal, en-member instruction set.

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West Mountain Observatory: Planning And Construction Pictorial History, Gene Libutti Jan 1982

West Mountain Observatory: Planning And Construction Pictorial History, Gene Libutti

BYU West Mountain Observatory Project

No abstract provided.

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Proton Induced X-Ray Emission Analysis - A Complement To Analytical Methods Used In Environmental Studies, N. F. Mangelson, D. J. Eatough, N. L. Eatough, L. D. Hansen, M. W. Hill, M. L. Lee, L. R. Phillips, M. E. Post, B. E. Richter, J. F. Ryder Apr 1981

Proton Induced X-Ray Emission Analysis - A Complement To Analytical Methods Used In Environmental Studies, N. F. Mangelson, D. J. Eatough, N. L. Eatough, L. D. Hansen, M. W. Hill, M. L. Lee, L. R. Phillips, M. E. Post, B. E. Richter, J. F. Ryder

Faculty Publications

Particle induced X-ray emission (PIXE) analysis is a highly versatile method of element analysis. Thus it is well suited for use as a complement to other methods of analysis in experimental programs requiring both chemical and elemental analyses. This paper reports some results of two projects where PIXE was used in conjunction with titration calorimetry, ion chromatography, atomic absorption spectroscopy, gas chromatography/mass spectrometry, X-ray fluorescence spectroscopy and some other methods. The first is a study of sulfur chemistry in a copper smelter plume. Arsenic was found to be a conservative tracer of the plume and was used for calculation of …

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Multiple Scattering Of Protons And Deuterons By Thick Foils, D. R. Dixon, G. L. Jensen, S. M. Morrill, C. J. Connors, R. L. Walter, C. R. Gould, P. M. Thambiduria Apr 1981

Multiple Scattering Of Protons And Deuterons By Thick Foils, D. R. Dixon, G. L. Jensen, S. M. Morrill, C. J. Connors, R. L. Walter, C. R. Gould, P. M. Thambiduria

Faculty Publications

Protons and deuterons from the Triangle Universities Nuclear Laboratory (TUNL) tandem Van de Graaff of energies 3.0, 4.0, and 5.0 MeV were scattered from foils of Al, Ni, Mo, and Ta having thicknesses of 6.14 to 47 mg/cm2. Multiple scattering angular distributions were measured using a position-sensitive detector to collect data at nine different angles simultaneously. Gaussian curves were fitted to the central points of the distributions and the Θ1/e angles thus derived are presented graphically. The data points are compared with calculations using a common method of determining multiple scattering angles. An empirical correction for extending this method into …

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Model For Coal-Fired Reactors, Philip J. Smith, Thomas H. Fletcher, L. Douglas Smoot Jan 1981

Model For Coal-Fired Reactors, Philip J. Smith, Thomas H. Fletcher, L. Douglas Smoot

Faculty Publications

An axisymmetric, elliptic model has been developed for analysis of confined, turbulent coal-laden diffusion flames. The scheme is Eulerian for gases and Lagrangian for particles. The approach emphasizes the turbulent fluid mechanics of the mixing-limited gas phase reaction processes. The two-equation (k-─ e) turbulence model is used for closure. Particle drag and turbulent particle diffusion are also modeled. Gaseous combustion is modeled with a probability density function for the mixture fraction. Fluctuations in mixing of inlet streams and coal off-gas are considered. Coal pyrolysis and oxidation reaction processes are assumed to be slow with respect to the turbulent time scale. …

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The Dufour Effect. Iii. Direct Experimental Determination Of The Heat Of Transport Of Carbon Tetrachloride-Cyclohexane Liquid Mixtures, Richard L. Rowley, Frederick H. Horne Jan 1980

The Dufour Effect. Iii. Direct Experimental Determination Of The Heat Of Transport Of Carbon Tetrachloride-Cyclohexane Liquid Mixtures, Richard L. Rowley, Frederick H. Horne

Faculty Publications

The heat of transport of carbon tetrachloride-cyclohexane liquid mixtures has been determined directly by Dufour effect experiments. The technique employs a withdrawable ''liquid gate'' to create a nonturbulent, sharp diffusional interface. The partial differential equations governing the barycentric velocity, composition, and temperature distributions are solved with a Crank-Nicholson implicit numerical scheme. This allows inclusion of the composition and temperature dependence of the thermodynamic and transport parameters. For mean mole fraction of carbon tetrachloride x1 between 0.34 and 0.55 and for mean temperature T between 295.13 and 296.43 degreesK, the best least squares fit of the data for the heat of …

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Program For New Observatory Facility For Brigham Young University, Provo, Utah, Byu Department Of Physics And Astronomy Nov 1979

Program For New Observatory Facility For Brigham Young University, Provo, Utah, Byu Department Of Physics And Astronomy

BYU West Mountain Observatory Project

No abstract provided.

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