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Testing of constitutive models in LAME.

Description: Constitutive models for computational solid mechanics codes are in LAME--the Library of Advanced Materials for Engineering. These models describe complex material behavior and are used in our finite deformation solid mechanics codes. To ensure the correct implementation of these models, regression tests have been created for constitutive models in LAME. A selection of these tests is documented here. Constitutive models are an important part of any solid mechanics code. If an analysis code is me… more
Date: September 1, 2007
Creator: Hammerand, Daniel Carl & Scherzinger, William Mark
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Transonic Approximation

Description: The following report develops the theory of an approximation for the transonic flow of a polytropic gas.
Date: March 1954
Creator: Diaz, J. B. & Ludford, G. S. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Numerical Modeling Analysis of Stress Transfer Modification Concepts for Deep Longwall Mines

Description: Abstract: This U. S. Bureau of Mines (USBM) report evaluates three stress-transfermodification concepts for their potential in reducing longwall gate road stresses and closures. In each of the three concepts - packwalling, gob infilling, and entry filling - support structures are constructed on the headgate side of the panel parallel with or inby the face line. When the headgate becomes the tailgate of the adjacent panel, these structures are in place to accept stresses transferred from the min… more
Date: 1995
Creator: Vandergrift, Thomas L. & Jude, Charles V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Constitutive models in LAME.

Description: The Library of Advanced Materials for Engineering (LAME) provides a common repository for constitutive models that can be used in computational solid mechanics codes. A number of models including both hypoelastic (rate) and hyperelastic (total strain) constitutive forms have been implemented in LAME. The structure and testing of LAME is described in Scherzinger and Hammerand ([3] and [4]). The purpose of the present report is to describe the material models which have already been implemented i… more
Date: September 1, 2007
Creator: Hammerand, Daniel Carl & Scherzinger, William Mark
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Reduced order models for thermal analysis : final report : LDRD Project No. 137807.

Description: This LDRD Senior's Council Project is focused on the development, implementation and evaluation of Reduced Order Models (ROM) for application in the thermal analysis of complex engineering problems. Two basic approaches to developing a ROM for combined thermal conduction and enclosure radiation problems are considered. As a prerequisite to a ROM a fully coupled solution method for conduction/radiation models is required; a parallel implementation is explored for this class of problems. High-fid… more
Date: September 1, 2010
Creator: Hogan, Roy E., Jr. & Gartling, David K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Modeling of friction-induced deformation and microstructures.

Description: Frictional contact results in surface and subsurface damage that could influence the performance, aging, and reliability of moving mechanical assemblies. Changes in surface roughness, hardness, grain size and texture often occur during the initial run-in period, resulting in the evolution of subsurface layers with characteristic microstructural features that are different from those of the bulk. The objective of this LDRD funded research was to model friction-induced microstructures. In order t… more
Date: December 1, 2006
Creator: Michael, Joseph Richard; Prasad, Somuri V.; Jungk, John Michael; Cordill, Megan J. (University of Minnesota); Bammann, Douglas J.; Battaile, Corbett Chandler et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Sales Forecasting Accuracy Over Time: An Empirical Investigation

Description: This study investigated forecasting accuracy over time. Several quantitative and qualitative forecasting models were tested and a number of combinational methods was investigated. Six time series methods, one causal model, and one subjective technique were compared in this study. Six combinational forecasts were generated and compared to individual forecasts. A combining technique was developed. Thirty data sets, obtained from a market leader in the cosmetics industry, were used to forecast sal… more
Date: May 1991
Creator: Zbib, Imad J.(Imad Jamil)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

KAYENTA : theory and user's guide.

Description: The physical foundations and domain of applicability of the Kayenta constitutive model are presented along with descriptions of the source code and user instructions. Kayenta, which is an outgrowth of the Sandia GeoModel, includes features and fitting functions appropriate to a broad class of materials including rocks, rock-like engineered materials (such as concretes and ceramics), and metals. Fundamentally, Kayenta is a computational framework for generalized plasticity models. As such, it in… more
Date: March 1, 2009
Creator: Brannon, Rebecca Moss (University of Utah, Salt Lake City, UT); Fossum, Arlo Frederick (BP America, Inc., Houston, TX) & Strack, Otto Eric
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Oil and Gas Supply Modeling

Description: Abstract: The symposium on Oil and Gas Supply Modeling, held at the Department of Commerce, Washington, DC (June 18-20, 1980), was funded by the Energy Information Administration of the Department of Energy and co-sponsored by the National Bureau of Standards' Operations Research Division. The symposium was organized to be a forum in which the theoretical and applied state-of-the-art of oil and gas supply models could be presented and discussed. Speakers addressed the following areas: the reali… more
Date: May 1982
Creator: Gass, Saul I.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Input Impedance of a Probe Antenna Exciting a TEM Cell

Description: Abstract: The input impedance of a probe antenna exciting a transverse electromagnetic (TEM) transmission line cell is formulated by a variational approach. The formulation also utilizes the results from a previous work on the field distribution inside a TEM cell excited by a vertical electrical Hertzian dipole. The final result of imoedance is shown to consist of two distinct terms, which are respectively contributed by the ordinary rectangular waveguide and the gap perturbation. Numerical res… more
Date: April 1982
Creator: Wilson, Perry F.; Chang, David C. & Ma, Mark T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Excitation of a TEM Cell by a Vertical Electric Hertzian Dipole

Description: From abstract: The excitation of a transverse electromagnetic (TEM) cell by a vertical electric Hertzian dipole is analyzed where the gap between the septum and side wall is assumed to be small. Approximate expressions for the field distribution and characteristic impedance are derived. These expressions are numerically evaluated for some typical geometries, and good agreement with previously published results is shown. The formation also allows a vertical offset for the septum position, thus o… more
Date: March 1981
Creator: Wilson, Perry F.; Chang, David C. & Ma, Mark T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Binary Solution Model for Computation of Equilibrium Compositions

Description: A NASA computer program (CEC) for calculation of complex equilibrium compositions has been modified to take into account the formation of an ideal binary solution from pure condensed species. The thermodynamics of the modification are discussed. Applications are presented.
Date: June 1978
Creator: Hsu, Chen C.; Land, Robert H. & Blander, Milton
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Precise Closed-Form Solutions of Some Mixed Boundary Value Problems of Plane Elasticity

Description: Precise solutions are given for the problem of the semi-infinite strip extending from x=0 to x=infinity, stress-free along the edges y= +-1, when the edge x=0 is subject (a) to a quadratic sheer displacement and zero normal stress, (b) to a cubic normal displacement and zero sheer stress. These are the two simplest (non-trivial) end problems of the semi-infinite strip, antisymmetric in y, that may be formulated. The corresponding symmetric problems (a) linear seer displacement and zero normal s… more
Date: 1954
Creator: Horvay, Gabriel, 1908- & Born, J. B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A decision-theoretic method for surrogate model selection.

Description: The use of surrogate models to approximate computationally expensive simulation models, e.g., large comprehensive finite element models, is widespread. Applications include surrogate models for design, sensitivity analysis, and/or uncertainty quantification. Typically, a surrogate model is defined by a postulated functional form; values for the surrogate model parameters are estimated using results from a limited number of solutions to the comprehensive model. In general, there may be multiple … more
Date: June 1, 2005
Creator: Field, Richard V., Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A turbulence model for buoyant flows based on vorticity generation.

Description: A turbulence model for buoyant flows has been developed in the context of a k-{var_epsilon} turbulence modeling approach. A production term is added to the turbulent kinetic energy equation based on dimensional reasoning using an appropriate time scale for buoyancy-induced turbulence taken from the vorticity conservation equation. The resulting turbulence model is calibrated against far field helium-air spread rate data, and validated with near source, strongly buoyant helium plume data sets. T… more
Date: October 1, 2005
Creator: Domino, Stefan Paul; Nicolette, Vernon F.; O'Hern, Timothy John; Tieszen, Sheldon R. & Black, Amalia Rebecca
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Sensitivity in risk analyses with uncertain numbers.

Description: Sensitivity analysis is a study of how changes in the inputs to a model influence the results of the model. Many techniques have recently been proposed for use when the model is probabilistic. This report considers the related problem of sensitivity analysis when the model includes uncertain numbers that can involve both aleatory and epistemic uncertainty and the method of calculation is Dempster-Shafer evidence theory or probability bounds analysis. Some traditional methods for sensitivity ana… more
Date: June 1, 2006
Creator: Tucker, W. Troy & Ferson, Scott
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Experimental assessment of unvalidated assumptions in classical plasticity theory.

Description: This report investigates the validity of several key assumptions in classical plasticity theory regarding material response to changes in the loading direction. Three metals, two rock types, and one ceramic were subjected to non-standard loading directions, and the resulting strain response increments were displayed in Gudehus diagrams to illustrate the approximation error of classical plasticity theories. A rigorous mathematical framework for fitting classical theories to the data, thus quanti… more
Date: January 1, 2009
Creator: Brannon, Rebecca Moss (University of Utah, Salt Lake City, UT); Burghardt, Jeffrey A. (University of Utah, Salt Lake City, UT); Bauer, Stephen J. & Bronowski, David R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

On the formulation of a crystal plasticity model.

Description: This report presents the formulation of a crystal elasto-viscoplastic model and the corresponding integration scheme. The model is suitable to represent the isothermal, anisotropic, large deformation of polycrystalline metals. The formulation is an extension of a rigid viscoplastic model to account for elasticity effects, and incorporates a number of changes with respect to a previous formulation [Marin & Dawson, 1998]. This extension is formally derived using the well-known multiplicative deco… more
Date: August 1, 2006
Creator: Marin, Esteban B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Final report for the ASC gas-powder two-phase flow modeling project AD2006-09.

Description: This report documents activities performed in FY2006 under the ''Gas-Powder Two-Phase Flow Modeling Project'', ASC project AD2006-09. Sandia has a need to understand phenomena related to the transport of powders in systems. This report documents a modeling strategy inspired by powder transport experiments conducted at Sandia in 2002. A baseline gas-powder two-phase flow model, developed under a companion PEM project and implemented into the Sierra code FUEGO, is presented and discussed here. Th… more
Date: January 1, 2007
Creator: Evans, Gregory Herbert & Winters, William S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Social Network Simulation and Mining Social Media to Advance Epidemiology

Description: Traditional Public Health decision-support can benefit from the Web and social media revolution. This dissertation presents approaches to mining social media benefiting public health epidemiology. Through discovery and analysis of trends in Influenza related blogs, a correlation to Centers for Disease Control and Prevention (CDC) influenza-like-illness patient reporting at sentinel health-care providers is verified. A second approach considers personal beliefs of vaccination in social media. A … more
Date: August 2009
Creator: Corley, Courtney David
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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