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A comparison of carrier approach speeds as determined from flight tests and from pilot-operated simulator studies

Description: Report presenting a simplified analog simulator that can be used to predict the minimum comfortable approach speeds that could be used in carrier landings for airplanes that are limited by their ability to control altitude. Predicted speeds from initial tests on several planes are compared with values from flight tests in order to indicate the validity of simulator results.
Date: June 19, 1957
Creator: White, Maurice D. & Drinkwater, Fred J., III
Partner: UNT Libraries Government Documents Department

Ground Simulator Studies of the Effects of Valve Friction, Stick Friction, Flexibility, and Backwash on Power Control System Quality

Description: Report presents results of tests made on a power control system by means of a ground simulator to determine the effects of various combinations of valve friction and stick friction on the ability of the pilot to control the system. Various friction conditions were simulated with a rigid control system, a flexible system, and a rigid system having some backlash. For the tests, the period and damping of the simulated airplane were held constant.
Date: February 8, 1957
Creator: Brown, B. Porter
Partner: UNT Libraries Government Documents Department

Simulator Investigation of Command Reaction Controls

Description: Memorandum presenting an investigation of reaction controls that command velocity and attitude that compares them to the controls that command acceleration. Proportional acceleration reaction controls were found to be satisfactory over a much wide range of control effectiveness than were the on-off acceleration controls. The velocity and attitude controls were found to be superior to either of the acceleration controls.
Date: July 17, 1958
Creator: Holleman, Euclid C. & Stillwell, Wendell H.
Partner: UNT Libraries Government Documents Department

An Air-Borne Target Simulator for Use With Scope-Presentation Type Fire-Control Systems

Description: Report describing the design and flight evaluation of an air-borne target simulator using precomputed relative kinematics for use in tracking studies of fighter aircraft equipped with scope-presentation type fire-control systems. Testing occurred in an F86D airplane equipped with a Hughes E-4 fire-control system. Results regarding relative kinematic programming considerations and restrictions to system evaluation are provided.
Date: May 10, 1957
Creator: Foster, John V.; Fulcher, Elmer C. & Heinle, Donovan R.
Partner: UNT Libraries Government Documents Department

The case of the missing supercomputer performance : achieving optimal performance on the 8, 192 processors of ASCI Q

Description: In this paper we describe how we improved the effective performance of ASCI Q, the world's second-fastest supercomputer, to meet our expectations. Using an arsenal of performance-analysis techniques including analytical models, custom microbenchmarks, full applications, and simulators, we succeeded in observing a serious-but previously undetectable-performance problem. We identified the source of the problem, eliminated the problem, and 'closed the loop' by demonstrating improved application performance. We present our methodology and provide insight into performance analysis that is immediately applicable to other large-scale cluster-based supercomputers.
Date: January 1, 2003
Creator: Petrini, F. (Fabrizio); Kerbyson, D. J. (Darren J.) & Pakin, S. D. (Scott D.)
Partner: UNT Libraries Government Documents Department

iTOUGH2 Command Reference

Description: iTOUGH2 is a program for parameter estimation, sensitivity analysis, and uncertainty propagation analysis. It is based on the TOUGH2 simulator for non-isothermal multiphase flow in fractured and porous media. This report contains a detailed description of all iTOUGH2 commands.
Date: June 18, 2002
Creator: Finsterle, Stefan
Partner: UNT Libraries Government Documents Department

iTOUGH2 Sample Problems

Description: iTOUGH2 is a program for parameter estimation, sensitivity analysis, and uncertainty propagation analysis. It is based on the TOUGH2 simulator for non-isothermal multiphase flow in fractured and porous media. This report contains a collection of iTOUGH2 sample problems.
Date: June 18, 2002
Creator: Finsterle, Stefan
Partner: UNT Libraries Government Documents Department

The Use of Simulation for the Design and Analysis of Thermophotovoltaic Networks

Description: Simulation has provided valuable quantification of the fundamental behavior of thermophotovoltaic cell networks. The results of simulation studies have supported the design and fabrication of small-scale demonstration networks and are expected to guide assembly of large-scale systems. This paper describes the methodology and software simulator developed to address issues in thermophotovoltaic (TPV) networking, including failure analysis, electrical network design, and nonuniform illumination. Results from simulation studies are given illustrating their application to the design and fabrication of small-scale TPV arrays.
Date: July 20, 2004
Creator: Oppenlander, JE; Vell, JL; Gaes, WS; Siganporia, DM; Danielson, LR & Dashiell, MW
Partner: UNT Libraries Government Documents Department

Qualitative Simulator Study of Longitudinal Stick Forces and Displacements Desirable During Tracking

Description: In this study in which an airplane simulator with one degree of freedom (pitch) was used, results were determined for three conditions of airplane dynamics. For an undamped natural frequency of 1/2 cps with a damping ratio of 0.18 and for an undamped natural frequency of 1 cps with a damping ratio of 0.11, moderate longitudinal stick forces and displacements were desired.
Date: February 1958
Creator: Faber, Stanley
Partner: UNT Libraries Government Documents Department

Spectral Measurements of Pulse Solar Simulators

Description: Spectral measurements of pulse solar simulators are used to quantify the wavelength-dependant characteristics of the light. Because every PV device has a unique spectral response, it is important to know the spectral irradiance and to periodically monitor the spectra for changes. Measurements are made at the National Renewable Energy Laboratory (NREL) using several different techniques including the NREL-developed Pulse Analysis Spectroradiometer System (PASS).
Date: November 12, 1998
Creator: Cannon, T. W.
Partner: UNT Libraries Government Documents Department

Production of Natural Gas and Fluid Flow in Tight Sand Reservoirs

Description: This document reports progress of this research effort in identifying possible relationships and defining dependencies between macroscopic reservoir parameters strongly affected by microscopic flow dynamics and production well performance in tight gas sand reservoirs. Based on a critical review of the available literature, a better understanding of the main weaknesses of the current state of the art of modeling and simulation for tight sand reservoirs has been reached. Progress has been made in the development and implementation of a simple reservoir simulator that is still able to overcome some of the deficiencies detected. The simulator will be used to quantify the impact of microscopic phenomena in the macroscopic behavior of tight sand gas reservoirs. Phenomena such as, Knudsen diffusion, electro-kinetic effects, ordinary diffusion mechanisms and water vaporization are being considered as part of this study. To date, the adequate modeling of gas slippage in porous media has been determined to be of great relevance in order to explain unexpected fluid flow behavior in tight sand reservoirs.
Date: June 30, 2005
Creator: Bravo, Maria Cecilia & Gurfinkel, Mariano
Partner: UNT Libraries Government Documents Department

Second Generation Advanced Reburning for High Efficiency NOx Control

Description: This project is designed to develop a family of novel NO{sub x} control technologies, called Second Generation Advanced Reburning (SGAR) which has the potential to achieve 90+% NO{sub x} control in coal-fired boilers at a significantly lower cost than SCR. The thirteenth reporting period in Phase II (October 1-December 31, 2000) included SGAR tests in which coal was used as the reburning fuel. All test work was conducted at GE-EER's 1.0 MMBtu/hr Boiler Simulator Facility. Three test series were performed including AR-Lean, AR-Rich, and reburning + SNCR. Tests demonstrated that over 90% NO{sub x} reduction could be achieved with utilization of coal as a reburning fuel in SGAR. The most effective SGAR variant is reburning + SNCR followed by AR-Lean and AR-Rich.
Date: December 31, 2000
Creator: Zamansky, Vladimir M.; Maly, Pete M. & Lissianski, Vitali V.
Partner: UNT Libraries Government Documents Department

Advanced Vadose Zone Simulations Using TOUGH

Description: The vadose zone can be characterized as a complex subsurfacesystem in which intricate physical and biogeochemical processes occur inresponse to a variety of natural forcings and human activities. Thismakes it difficult to describe, understand, and predict the behavior ofthis specific subsurface system. The TOUGH nonisothermal multiphase flowsimulators are well-suited to perform advanced vadose zone studies. Theconceptual models underlying the TOUGH simulators are capable ofrepresenting features specific to the vadose zone, and of addressing avariety of coupled phenomena. Moreover, the simulators are integratedinto software tools that enable advanced data analysis, optimization, andsystem-level modeling. We discuss fundamental and computationalchallenges in simulating vadose zone processes, review recent advances inmodeling such systems, and demonstrate some capabilities of the TOUGHsuite of codes using illustrative examples.
Date: February 1, 2007
Creator: Finsterle, S.; Doughty, C.; Kowalsky, M.B.; Moridis, G.J.; Pan,L.; Xu, T. et al.
Partner: UNT Libraries Government Documents Department

Circuit simulation: some humbling thoughts

Description: A short, very personal note on circuit simulation is presented. It does neither include theoretical background on circuit simulation, nor offers an overview of available software, but just gives some general remarks for a discussion on circuit simulator needs in context to the design and development of accelerator beam instrumentation circuits and systems.
Date: January 1, 2006
Creator: Wendt, Manfred
Partner: UNT Libraries Government Documents Department

On fluid flow in a heterogeneous medium under nonisothermal conditions

Description: An asymptotic technique, valid in the presence of smoothly-varying heterogeneity, provides explicit expressions for the velocity of a propagating pressure and temperature disturbance. The governing equations contain nonlinear terms due to the presence of temperature-dependent coefficients and due to the advection of fluids with differing temperatures. Two cases give well-defined expressions in terms of the parameters of the porous medium: the uncoupled propagation of a pressure disturbance and the propagation of a fully coupled temperature and pressure disturbance. The velocity of the coupled disturbance or front, depends upon the medium parameters and upon the change in temperature and pressure across the front. For uncoupled flow, the semi-analytic expression for the front velocity reduces to that associated with a linear diffusion equation. A comparison of the asymptotic travel time estimates with calculations from a numerical simulator indicates reasonably good agreement for both uncoupled and coupled disturbances.
Date: November 1, 2010
Creator: D.W., Vasco
Partner: UNT Libraries Government Documents Department

A New Parameter to Assess Hydromechanical Effect in Single-hole Hydraulic Testing and Grouting

Description: Grouting or filling of the open voids in fractured rock is done by introducing a fluid, a grout, through boreholes under pressure. The grout may be either a Newtonian fluid or a Bingham fluid. The penetration of the grout and the resulting pressure profile may give rise to hydromechanical effects, which depends on factors such as the fracture aperture, pressure at the borehole and the rheological properties of the grout. In this paper, we postulate that a new parameter, {angstrom}, which is the integral of the fluid pressure change in the fracture plane, is an appropriate measure to describe the change in fracture aperture volume due to a change in effective stress. In many cases, analytic expressions are available to calculate pressure profiles for relevant input data and the {angstrom} parameter. The approach is verified against a fully coupled hydromechanical simulator for the case of a Newtonian fluid. Results of the verification exercise show that the new approach is reasonable and that the {angstrom}-parameter is a good measure for the fracture volume change: i.e., the larger the {angstrom}-parameter, the larger the fracture volume change, in an almost linear fashion. To demonstrate the application of the approach, short duration hydraulic tests and constant pressure grouting are studied. Concluded is that using analytic expressions for penetration lengths and pressure profiles to calculate the {angstrom} parameter provides a possibility to describe a complex situation and compare, discuss and weigh the impact of hydromechanical couplings for different alternatives. Further, the analyses identify an effect of high-pressure grouting, where uncontrolled grouting of larger fractures and insufficient (or less-than-expected) sealing of finer fractures is a potential result.
Date: September 1, 2007
Creator: Rutqvist, Jonny; Fransson, A.; Tsang, C.-F.; Rutqvist, J. & Gustafson, G.
Partner: UNT Libraries Government Documents Department

Wellbore Models GWELL, GWNACL, and HOLA User's Guide

Description: This report describes three multi-component, multi-feedzone geothermal wellbore simulators developed. These simulators reproduce the measured flowing temperature and pressure profiles in flowing wells and determine the relative contribution, fluid properties (e.g. enthalpy, temperature) and fluid composition (e.g. CO{sub 2}, NaCl) of each feedzone for a given discharge condition. The three related wellbore simulators that will be discussed here are HOLA, GWELL and GWNACL. HOLA is a multi-feedzone geothermal wellbore simulator for pure water, modified after the wellbore simulator developed by Bjornsson, 1987 and can now handle deviated wells. The other two simulators GWELL (see also Aunzo, 1990) and GWNACL are modified versions of HOLA that can handle H{sub 2}O-CO{sub 2} and H{sub 2}O-NaCl systems, respectively. These simulators can handle both single and two-phase flows in vertical and inclined pipes and calculate the flowing temperature and pressure profiles in the well. The simulators solve numerically the differential equations that describe the steady-state energy, mass and momentum flow in a pipe. The codes allow for multiple feedzones, variable grid spacing and well radius. These codes were developed using FORTRAN language on the UNIX system.
Date: October 1, 1991
Creator: Aunzo, Z.P.; Bjornsson, G. & Bodvarsson, G.S.
Partner: UNT Libraries Government Documents Department

Performance characteristics of a cosmology package on leading HPCarchitectures

Description: The Cosmic Microwave Background (CMB) is a snapshot of the Universe some 400,000 years after the Big Bang. The pattern of anisotropies in the CMB carries a wealth of information about the fundamental parameters of cosmology. Extracting this information is an extremely computationally expensive endeavor, requiring massively parallel computers and software packages capable of exploiting them. One such package is the Microwave Anisotropy Dataset Computational Analysis Package (MADCAP) which has been used to analyze data from a number of CMB experiments. In this work, we compare MADCAP performance on the vector-based Earth Simulator (ES) and Cray X1 architectures and two leading superscalar systems, the IBM Power3 and Power4. Our results highlight the complex interplay between the problem size, architectural paradigm, interconnect, and vendor-supplied numerical libraries, while isolating the I/O file system as the key bottleneck across all the platforms.
Date: January 1, 2004
Creator: Carter, Jonathan; Borrill, Julian & Oliker, Leonid
Partner: UNT Libraries Government Documents Department

A New Generation Chemical Flooding Simulator

Description: The premise of this research is that a general-purpose reservoir simulator for several improved oil recovery processes can and should be developed so that high-resolution simulations of a variety of very large and difficult problems can be achieved using state-of-the-art computing and computers. Such a simulator is not currently available to the industry. The goal of this proposed research is to develop a new-generation chemical flooding simulator that is capable of efficiently and accurately simulating oil reservoirs with at least a million gridblocks in less than one day on massively parallel computers. Task 1 is the formulation and development of solution scheme, Task 2 is the implementation of the chemical module, and Task 3 is validation and application. We have made significant progress on all three tasks and we are on schedule on both technical and budget. In this report, we will detail our progress on Tasks 1 through 3 for the first six months of the project.
Date: March 1, 2002
Creator: Pope, Gary A.; Sepehrnoori, Kamy & Delshad, Mojdeh
Partner: UNT Libraries Government Documents Department

Reservoir Characterization of Upper Devonian Gordon Sandstone, Jacksonburg, Stringtown Oil Field, Northwestern West Virginia

Description: This report gives results of efforts to determine electrofacies from logs; measure permeability in outcrop to study very fine-scale trends; find the correlation between permeability measured by the minipermeameter and in core plugs, define porosity-permeability flow units; and run the BOAST III reservoir simulator using the flow units defined for the Gordon reservoir.
Date: May 21, 2002
Creator: Ameri, S.; Aminian, K.; Avary, K.L.; Bilgesu, H.I.; Hohn, M.E.; McDowell, R.R. et al.
Partner: UNT Libraries Government Documents Department

Solutions of test problems for disposal of CO2 in saline aquifers

Description: This report presents detailed results for three flow problems involving CO2 migration in saline aquifers, that had been posed as part of an international code intercomparison study. Selected data for PVT properties of aqueous mixtures involving CO2 are given, and the dynamics of immiscible displacement of an aqueous phase by supercritical CO2 is discussed. Simulations were conducted with a version of the TOUGH2 general purpose reservoir simulator that includes a special property package for supercritical CO2. The results can serve as benchmarks for debugging numerical simulation models.
Date: March 5, 2003
Creator: Pruess, Karsten & Garcia, Julio
Partner: UNT Libraries Government Documents Department

iTOUGH2: From parameter estimation to model structure identification

Description: iTOUGH2 provides inverse modeling capabilities for the TOUGH2 family of nonisothermal multiphase flow simulators. It can be used for a formalized sensitivity analysis, parameter estimation by automatic model calibration, and uncertainty propagation analyses. While iTOUGH2 has been successfully applied for the estimation of a variety of parameters based on different data types, it is recognized that errors in the conceptual model have a great impact on both the estimated parameters and the subsequent model predictions. Identification of the most suitable model structure is therefore one of the most important and most difficult tasks. Within the iTOUGH2 framework, model identification can be partly addressed through appropriate parameterization of alternative conceptual-model elements. In addition, statistical measures are provided that help rank the performance of different conceptual models. We present a number of features added to the code that allow for a better parameterization of conceptual model elements, specifically heterogeneity. We discuss how these new features can be used to support the identification of key model structure elements and their impact on model predictions.
Date: May 12, 2003
Creator: Finsterle, Stefan
Partner: UNT Libraries Government Documents Department