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3-body final states in peripheral heavy-ion collisions: nuclear clustering structure and projectile excitation revisited (open access)

3-body final states in peripheral heavy-ion collisions: nuclear clustering structure and projectile excitation revisited

Even though peripheral heavy-ion collisions are less violent than their central counterparts, the large energy exchange between the reactants often leaves the primary products in excited particle-unstable states whose subsequent decay leads to 3 or more nuclei emerging in the final exit channel. These post-reaction, predominantly sequential de-excitation processes can sometimes provide interesting structural information about the parent nuclei. In fact, provided these processes are well understood, one can employ them as probes for studying initial properties of the fragments. This report discusses results of two experiments that deal with (1) nonstatistical, rare decay modes of the projectile, and (2) internal excitation energy of the projectile- and target-like fragments in peripheral collisions. The physics addressed in each is different, but the experimental and data-analysis techniques are so similar that it is relevant to join them together.
Date: February 1, 1986
Creator: Chan, Y.; Chavez, E.; Gazes, S.B.; Kamermans, R.; Schmidt, H.R.; Siwek-Wilczynska, J. et al.
Object Type: Article
System: The UNT Digital Library
3-D Analysis on Arbitrarily-Shaped Icrf Antennas and Faraday Shields (open access)

3-D Analysis on Arbitrarily-Shaped Icrf Antennas and Faraday Shields

Cavity antennas with Faraday shields are proposed to couple ion cyclotron radio frequency power for heating fusion plasmas. This application requires small, high-power, low-frequency antennas. The results are presented of a theoretical study of the ICRF antennas being developed for this purpose at the Radio Frequency Test Facility (RFTF). The objectives of this work are to optimize experimental designs and to confirm test results. (MOW)
Date: January 1, 1986
Creator: Chen, G. L.; Whealton, J. H.; Baity, F. W.; Hoffman, D. J. & Owens, T. L.
Object Type: Article
System: The UNT Digital Library
3-D Cavern Enlargement Analyses (open access)

3-D Cavern Enlargement Analyses

Three-dimensional finite element analyses simulate the mechanical response of enlarging existing caverns at the Strategic Petroleum Reserve (SPR). The caverns are located in Gulf Coast salt domes and are enlarged by leaching during oil drawdowns as fresh water is injected to displace the crude oil from the caverns. The current criteria adopted by the SPR limits cavern usage to 5 drawdowns (leaches). As a base case, 5 leaches were modeled over a 25 year period to roughly double the volume of a 19 cavern field. Thirteen additional leaches where then simulated until caverns approached coalescence. The cavern field approximated the geometries and geologic properties found at the West Hackberry site. This enabled comparisons are data collected over nearly 20 years to analysis predictions. The analyses closely predicted the measured surface subsidence and cavern closure rates as inferred from historic well head pressures. This provided the necessary assurance that the model displacements, strains, and stresses are accurate. However, the cavern field has not yet experienced the large scale drawdowns being simulated. Should they occur in the future, code predictions should be validated with actual field behavior at that time. The simulations were performed using JAS3D, a three dimensional finite element analysis …
Date: March 1, 2002
Creator: EHGARTNER, BRIAN L. & SOBOLIK, STEVEN R.
Object Type: Report
System: The UNT Digital Library
3-D DETERMINISTIC TRANSPORT METHODS RESEARCH AT LANL UNDER ASCI (open access)

3-D DETERMINISTIC TRANSPORT METHODS RESEARCH AT LANL UNDER ASCI

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Date: January 1, 2000
Creator: Morel, J.
Object Type: Article
System: The UNT Digital Library
A 3-D dynamical/chemical GCM for simulating the anthropogenical effects on ozone (open access)

A 3-D dynamical/chemical GCM for simulating the anthropogenical effects on ozone

In spite of the significantly increased attention atmospheric ozone has received over the last two decades or so, a fully quantitative understanding of the three-dimensional ozone structure remains unavailable. In the past, one-dimensional (vertical column) models have provided most of the quantitative simulations of atmospheric chemical systems, because these models can treat large ensembles of chemical process economically. More recently, two-dimensional (meridional cross section) models have become popular, in part because of increasing computer capabilities. There has been little work using a sophisticated 3-D GCM coupled with a comprehensive photochemical model to study the chemical-dynamical interactions involving the ozone abundance. Namely, either the dynamics or the chemistry is too simplified in most of the existing models. Relatively more advanced photochemistry has been included in the stratospheric models (dealing the vertical domain from 20 to 70 km above the surface) at the expense of tropospheric details. An important motivation for this research has been the desire to estimate the magnitude of changes in the ozone layer induced by anthropogenic perturbations such as the injection of oxides of nitrogen and chlorine compounds. Accordingly, the attempt has been to develop a complete but feasible photochemical scheme and to combine it with the Los …
Date: January 1, 1989
Creator: Kao, C. Y. J.; Glatzmaier, G. A.; Malone, R. C. & Turco, R. P.
Object Type: Article
System: The UNT Digital Library
3-D field computations for accelerator magnets using finite element and integral codes (open access)

3-D field computations for accelerator magnets using finite element and integral codes

Two dimensional (2-D) computation has been an accepted part of the design of accelerator magnets since the 1960`s, but three-dimensional (3-D) computations are still not fully trusted. This paper describes the successes and limitations of 3-D computations, as applied to accelerator magnets for the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). Both the finite element code TOSCA and the edge element volume integral code CORAL have been used in these computations. The ends of the dipole bending magnet for the injector synchrotron were designed using TOSCA; comparisons with measurements are described. Computation of other APS magnets are also described.
Date: December 1, 1992
Creator: Turner, L. R.; Kim, S. H.; Kim, K. & Kettunen, L.
Object Type: Article
System: The UNT Digital Library
3-D Finite Element Analyses of the Egan Cavern Field (open access)

3-D Finite Element Analyses of the Egan Cavern Field

Three-dimensional finite element analyses were performed for the two gas-filled storage caverns at the Egan field, Jennings dome, Louisiana. The effects of cavern enlargement on surface subsidence, storage loss, and cavern stability were investigated. The finite element model simulated the leaching of caverns to 6 and 8 billion cubic feet (BCF) and examined their performance at various operating conditions. Operating pressures varied from 0.15 psi/ft to 0.9 psi/ft at the bottom of the lowest cemented casing. The analysis also examined the stability of the web or pillar of salt between the caverns under differential pressure loadings. The 50-year simulations were performed using JAC3D, a three dimensional finite element analysis code for nonlinear quasistatic solids. A damage criterion based on onset of dilatancy was used to evaluate cavern instability. Dilation results from the development of microfractures in salt and, hence, potential increases in permeability onset occurs well before large scale failure. The analyses predicted stable caverns throughout the 50-year period for the range of pressures investigated. Some localized salt damage was predicted near the bottom walls of the caverns if the caverns are operated at minimum pressure for long periods of time. Volumetric cavern closures over time due to creep were …
Date: February 1, 1999
Creator: Klamerus, E.W. & Ehgartner, B.L.
Object Type: Report
System: The UNT Digital Library
3-d finite element model development for biomechanics: a software demonstration (open access)

3-d finite element model development for biomechanics: a software demonstration

Finite element analysis is becoming an increasingly important part of biomechanics and orthopedic research, as computational resources become more powerful, and data handling algorithms become more sophisticated. Until recently, tools with sufficient power did not exist or were not accessible to adequately model complicated, three-dimensional, nonlinear biomechanical systems. In the past, finite element analyses in biomechanics have often been limited to two-dimensional approaches, linear analyses, or simulations of single tissue types. Today, we have the resources to model fully three-dimensional, nonlinear, multi-tissue, and even multi-joint systems. The authors will present the process of developing these kinds of finite element models, using human hand and knee examples, and will demonstrate their software tools.
Date: March 1, 1997
Creator: Hollerbach, K.; Hollister, A.M. & Ashby, E.
Object Type: Article
System: The UNT Digital Library
3-D heat transfer computer calculations of the performance of the IAEA's air-bath calorimeters (open access)

3-D heat transfer computer calculations of the performance of the IAEA's air-bath calorimeters

A three dimensional (3-D) heat transfer computer code was developed to study and optimize the design parameters and to better understand the performance characteristics of the IAEA's air-bath calorimeters. The computer model accounts for heat conduction and radiation in the complex materials of the calorimeter and for heat convection and radiation at its outer surface. The temperature servo controller is modelled as an integral part of the heat balance equations in the system. The model predictions will be validated against test data using the ANL bulk calorimeter. 11 refs., 6 figs.
Date: January 1, 1989
Creator: Elias, E.; Kaizermann, S.; Perry, R. B. & Fiarman, S.
Object Type: Article
System: The UNT Digital Library
3-D hybrid PIC code to model the tilt mode in FRCs (open access)

3-D hybrid PIC code to model the tilt mode in FRCs

The results from QN3D are presented. QN3D is a 3-dimensional hybrid particle-in-cell code designed to run efficiently on the Cray-2 Multiprocessor. The chief application has been to the tilt mode instability in FRCs. QN3D accepts as input, the magnetic field, the ion particle density and the ion temperature on a two-dimensional r-z grid. These quantities are interpolated to the rest of the cartesian grid under the assumption of azimuthal symmetry. The particles are initialized with random numbers chosen according to the particle distributions input from the equilibrium code. The runs done here used equilibria computed by EQV, a kinetic equilibrium code.
Date: June 1, 1987
Creator: Horowitz, E. J. & Shumaker, D. E.
Object Type: Article
System: The UNT Digital Library
3-D magnetic field calculations for wiggglers using MAGNUS-3D (open access)

3-D magnetic field calculations for wiggglers using MAGNUS-3D

The recent but steady trend toward increased magnetic and geometric complexity in the design of wigglers and undulators, of which tapered wigglers, hybrid structures, laced electromagnetic wigglers, magnetic cladding, twisters and magic structures are examples, has caused a need for reliable 3-D computer models and a better understanding of the behavior of magnetic systems in three dimensions. The capabilities of the MAGNUS-3D Group of Programs are ideally suited to solve this class of problems and provide insight into 3-D effects. MAGNUS-3D can solve any problem of Magnetostatics involving permanent magnets, linear or nonlinear ferromagnetic materials and electric conductors of any shape in space. The magnetic properties of permanent magnets are described by the complete nonlinear demagnetization curve as provided by the manufacturer, or, at the user's choice, by a simpler approximation involving the coercive force, the residual induction and the direction of magnetization. The ferromagnetic materials are described by a magnetization table and an accurate interpolation relation. An internal library with properties of common industrial steels is available. The conductors are independent of the mesh and are described in terms of conductor elements from an internal library.
Date: January 1, 1988
Creator: Pissanetzky, S. & Tompkins, P.
Object Type: Article
System: The UNT Digital Library
A 3-D measurement system using object-oriented FORTH (open access)

A 3-D measurement system using object-oriented FORTH

Discussed is a system for storing 3-D measurements of points that relates the coordinate system of the measurement device to the global coordinate system. The program described here used object-oriented FORTH to store the measured points as sons of the measuring device location. Conversion of local coordinates to absolute coordinates is performed by passing messages to the point objects. Modifications to the object-oriented FORTH system are also described. 1 ref.
Date: January 1, 1989
Creator: Butterfield, K.B.
Object Type: Article
System: The UNT Digital Library
A 3-D Model of Signaling and Transport Pathways in Epithelial Cells (open access)

A 3-D Model of Signaling and Transport Pathways in Epithelial Cells

A 3-dimensional computer model was developed to simulate the spatial and chemical evolution of calcium ions inside an array of human epithelial kidney cells. This is a prototype model, intended to develop a methodology to incorporate much more complex interactions of metabolic and other processes within many types of cells and lead to increased ability to predict cellular responses to disease as well as to chemical and biological warfare situations. Preliminary tests of the model are described.
Date: April 1, 2005
Creator: Quong, Andrew A. & Westbrook, Charles K.
Object Type: Report
System: The UNT Digital Library
A 3-D model of superfluid helium suitable for numerical analysis (open access)

A 3-D model of superfluid helium suitable for numerical analysis

The two-fluid description is a very successful phenomenological representation of the properties of Helium II. A 3-D model suitable for numerical analysis based on the Landau-Khalatnikov description of Helium II is proposed. In this paper we introduce a system of partial differential equations that is both complete and consistent as well as practical, to be used for a 3-D solution of the flow of Helium II. The development of a 3-D numerical model for Helium II is motivated by the need to validate experimental results obtained by observing the normal component velocity distribution in a Helium II thermal counter-flow using the Particle Image Velocimetry (PIV) technique.
Date: January 1, 2008
Creator: Darve, C.; U., /Fermilab /Northwestern; Patankar, N.A.; U., /Northwestern; Van Sciver, S.W. & Lab., /Natl. High Mag. Field
Object Type: Article
System: The UNT Digital Library
A 3-d modular gripper design tool (open access)

A 3-d modular gripper design tool

Modular fixturing kits are precisely machined sets of components used for flexible, short-turnaround construction of fixtures for a variety of manufacturing purposes. A modular vise is a parallel-jaw vise, where each jaw is a modular fixture plate with a regular grid of precisely positioned holes. A modular vise can be used to locate and hold parts for machining, assembly, and inspection tasks. To fixture a part, one places pins in some of the holes so that when the vise is closed, the part is reliably located and completely constrained. The modular vise concept can be adapted easily to the design of modular parallel-jaw grippers for robots. By attaching a grid plate to each jaw of a parallel-jaw gripper, the authors gain the ability to easily construct high-quality grasps for a wide variety of parts from a standard set of hardware. Wallack and Canny developed a previous algorithm for planning planar grasp configurations for the modular vise. In this paper, the authors expand this work to produce a 3-d fixture/gripper design tool. They describe several analyses added to the planar algorithm to improve its utility, including a three-dimensional grasp quality metric based on geometric and force information, three-dimensional geometric loading analysis, …
Date: January 1, 1997
Creator: Brown, R.G. & Brost, R.C.
Object Type: Report
System: The UNT Digital Library
A 3-d modular gripper design tool (open access)

A 3-d modular gripper design tool

Modular fixturing kits are sets of components used for flexible, rapid construction of fixtures. A modular vise is a parallel-jaw vise, each jaw of which is a modular fixture plate with a regular grid of precisely positioned holes. To fixture a part, one places pins in some of the holes so that when the vise is closed, the part is reliably located and completely constrained. The modular vise concept can be adapted easily to the design of modular parallel-jaw grippers for robots. By attaching a grid-plate to each jaw of a parallel-jaw gripper, one gains the ability to easily construct high-quality grasps for a wide variety of parts from a standard set of hardware. Wallack and Canny developed an algorithm for planning planar grasp configurations for the modular vise. In this paper, the authors expand this work to produce a 3-d fixture/gripper design tool. They describe several analyses they have added to the planar algorithm, including a 3-d grasp quality metric based on force information, 3-d geometric loading analysis, and inter-gripper interference analysis. Finally, the authors describe two applications of their code. One of these is an internal application at Sandia, while the other shows a potential use of the …
Date: February 1, 1997
Creator: Brown, R.G. & Brost, R.C.
Object Type: Article
System: The UNT Digital Library
3-D Nonlinear Calculations of Resistive Tearing Modes (open access)

3-D Nonlinear Calculations of Resistive Tearing Modes

Recent numerical calculations of the evolution of resistive tearing modes have been central to the understanding of magnetohydrodynamic activity and disruptions in tokamaks. The nonlinear, 3-D, initial-value computer code RSF has provided many of these results. This code assumes cylindrical geometry with a Fourier series representation in the two periodic coordinates and a finite-difference representation in the radial direction. This choice makes RSF considerably more accurate and efficient than previous codes.
Date: March 1, 1981
Creator: Hicks, H. R.; Holmes, J. A.; Lee, D. K.; Carreras, B. & Waddell, B. V.
Object Type: Report
System: The UNT Digital Library
3-D nonlinear evolution of MHD instabilities (open access)

3-D nonlinear evolution of MHD instabilities

The nonlinear evolution of ideal MHD internal instabilities is investigated in straight cylindrical geometry by means of a 3-D initial-value computer code. These instabilities are characterized by pairs of velocity vortex cells rolling off each other and helically twisted down the plasma column. The cells persist until the poloidal velocity saturates at a few tenths of the Alfven velocity. The nonlinear phase is characterized by convection around these essentially fixed vortex cells. For example, the initially centrally peaked temperature profile is convected out and around to form an annulus of high temperature surrounding a small region of lower temperature. Weak, centrally localized instabilities do not alter the edge of the plasma. Strong, large-scale instabilities, resulting from a stronger longitudinal equilibrium current, drive the plasma against the wall. After three examples of instability are analyzed in detail, the numerical methods and their verification are discussed.
Date: March 1, 1977
Creator: Bateman, G.; Hicks, H. R. & Wooten, J. W.
Object Type: Report
System: The UNT Digital Library
3-D numerical investigation of the mantle dynamics associated with the breakup of Pangea (open access)

3-D numerical investigation of the mantle dynamics associated with the breakup of Pangea

Three-dimensional finite element calculations in spherical geometry are performed to study the response of the mantle with platelike blocks at its surface to an initial condition corresponding to subduction along the margins of Pangea. The mantle is treated as an infinite Prandtl number Boussinesq fluid inside a spherical shell with isothermal, undeformable, free-slip boundaries. Nonsubducting rigid blocks to model continental lithosphere are included in the topmost layer of the computational mesh. At the beginning of the numerical experiments these blocks represent the present continents mapped to their approximate Pangean positions. Asymmetrical downwelling at the margins of these nonsubducting blocks results in a pattern of stresses that acts to pull the supercontinent apart. The calculations suggest that the breakup of Pangea and the subsequent global pattern of seafloor spreading was driven largely by the subduction at the Pangean margins.
Date: January 1, 1992
Creator: Baumgardner, J. R.
Object Type: Article
System: The UNT Digital Library
3-D numerical investigation of the mantle dynamics associated with the breakup of Pangea (open access)

3-D numerical investigation of the mantle dynamics associated with the breakup of Pangea

Three-dimensional finite element calculations in spherical geometry are performed to study the response of the mantle with platelike blocks at its surface to an initial condition corresponding to subduction along the margins of Pangea. The mantle is treated as an infinite Prandtl number Boussinesq fluid inside a spherical shell with isothermal, undeformable, free-slip boundaries. Nonsubducting rigid blocks to model continental lithosphere are included in the topmost layer of the computational mesh. At the beginning of the numerical experiments these blocks represent the present continents mapped to their approximate Pangean positions. Asymmetrical downwelling at the margins of these nonsubducting blocks results in a pattern of stresses that acts to pull the supercontinent apart. The calculations suggest that the breakup of Pangea and the subsequent global pattern of seafloor spreading was driven largely by the subduction at the Pangean margins.
Date: October 1, 1992
Creator: Baumgardner, J. R.
Object Type: Article
System: The UNT Digital Library
A 3-D numerical study of pinhole diffraction to predict the accuracy of EUV point diffraction interferometry (open access)

A 3-D numerical study of pinhole diffraction to predict the accuracy of EUV point diffraction interferometry

A 3-D electromagnetic field simulation is used to model the propagation of extreme ultraviolet (EUV), 13-nm, light through sub-1500 {Angstrom} dia pinholes in a highly absorptive medium. Deviations of the diffracted wavefront phase from an ideal sphere are studied within 0.1 numerical aperture, to predict the accuracy of EUV point diffraction interferometersused in at-wavelength testing of nearly diffraction-limited EUV optical systems. Aberration magnitudes are studied for various 3-D pinhole models, including cylindrical and conical pinhole bores.
Date: December 1, 1995
Creator: Goldberg, K.A.; Tejnil, E. & Bokor, J.
Object Type: Article
System: The UNT Digital Library
A 3-D ray-trace model for an AMR code on distributed processors (open access)

A 3-D ray-trace model for an AMR code on distributed processors

Distributed memory AMR codes provide a special challenge for laser ray-trace modeling. For RAGE we follow the energy-carrying rays through each cell, checking for crossings which require collection a new cell index (1 of 9 in 2D). Density gradients for ray deflections can be calculated 'on the fly.' Substantial excursions must be made from the legacy PIC particle area-weighting approach, but this serves as a useful 1st step. Similarly, IDL now offers a quick graphical rendering, while ENSIGHT graphics beautifully captures the 3D light refraction and deposition.
Date: January 1, 2002
Creator: Mason, R. J. (Rodney J.)
Object Type: Article
System: The UNT Digital Library
3-D Ray-tracing and 2-D Fokker-Planck Simulations of Radiofrequency Application to Tokamak Plasmas (open access)

3-D Ray-tracing and 2-D Fokker-Planck Simulations of Radiofrequency Application to Tokamak Plasmas

A state of the art numerical tool has been developed to simulate the propagation and the absorption of coexisting different types of waves in a tokamak geometry. The code includes a numerical solution of the three-dimensional (R, Z, {Phi}) toroidal wave equation for the electric field of the different waves in the WKBJ approximation. At each step of integration, the two-dimensional (v{sub {parallel}}, v{sub {perpendicular}}) Fokker-Planck equation is solved in the presence of quasilinear diffusion coefficients. The electron Landau damping of the waves is modeled taking into account the interaction of the wave electric fields with the quasilinearly modified distribution function. Consistently, the code calculates the radial profiles of non-inductively generated current densities, the transmitted power traces and the total power damping curves. Synergistic effects among the different type of waves (e.g., lower hybrid and ion Bernstein waves) are studied through the separation of the contributions of the single wave from the effects due to their coexistence.
Date: May 1, 1999
Creator: Cardinali, A.; Paoletti, F. & Bernabei, S.
Object Type: Report
System: The UNT Digital Library
3-D research transport codes at Los Alamos (open access)

3-D research transport codes at Los Alamos

We describe 3-D research transport codes which have been developed at Los Alamos National Laboratory over the last three years. Some simple example calculations are presented.
Date: October 1, 1994
Creator: Morel, J. E.; McGhee, J. M. & Walters, W. F.
Object Type: Article
System: The UNT Digital Library