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Visualization Tools for Adaptive Mesh Refinement Data

Description: Adaptive Mesh Refinement (AMR) is a highly effective method for simulations that span a large range of spatiotemporal scales, such as astrophysical simulations that must accommodate ranges from interstellar to sub-planetary. Most mainstream visualization tools still lack support for AMR as a first class data type and AMR code teams use custom built applications for AMR visualization. The Department of Energy's (DOE's) Science Discovery through Advanced Computing (SciDAC) Visualization and Analytics Center for Enabling Technologies (VACET) is currently working on extending VisIt, which is an open source visualization tool that accommodates AMR as a first-class data type. These efforts will bridge the gap between general-purpose visualization applications and highly specialized AMR visual analysis applications. Here, we give an overview of the state of the art in AMR visualization research and tools and describe how VisIt currently handles AMR data.
Date: May 9, 2007
Creator: Weber, Gunther H.; Beckner, Vincent E.; Childs, Hank; Ligocki,Terry J.; Miller, Mark C.; Van Straalen, Brian et al.
Partner: UNT Libraries Government Documents Department

ALE advantage in hypervelocity impact calculations

Description: The ALE3D code is used to model experiments relevant to hypervelocity impact lethality, carried out in the 4-5 km/s velocity range. The code is run in the Eulerian and ALE modes. Zoning in the calculations is refined beyond the level found in most lethality calculations, but still short of convergence. The level of zoning refinement that produces equivalent results in uniformly zoned Eulerian calculations and ALE ones utilizing specialized zoning, weighting and relaxation techniques is established. It takes 11 times fewer zones and about 60% as many cycles when ALE capabilities are used. Calculations are compared to experimental results.
Date: October 1, 1998
Creator: Gerassimenko, M. & Rathkopf, J.
Partner: UNT Libraries Government Documents Department

Transverse Mode Coupling Instability in a Double RF System

Description: The equations for transverse mode coupling in a storage ring with a double rf system are derived from a Hamiltonian formalism. The resulting integral equation is expanded into a set of orthogonal polynomials, and the expansion coefficients are then given by the solution of an infinite determinant. Truncation of this determinant permits solution of the problem on a computer, and a code has been written which finds the complex mode frequencies. The stability limits of LEP with a third harmonic are determined by equating the imaginary part of the solution to the radiation damping rate.
Date: February 1, 1993
Creator: Chin, Y.-H.
Partner: UNT Libraries Government Documents Department

Analysis of KEK-ATF optics and coupling using orbit response matrix analysis

Description: LOCO is a code for analysis of the linear optics in a storage ring based on the closed orbit response to steering magnets. The analysis provides information on focusing errors, BPM gain and rotation errors, and local coupling. Here, we report the results of an application of LOCO to the KEK-ATF. Although the analysis appears to have provided useful information on the optics of the machine, it appears that one of the main aims of the study--to reduce the vertical emittance by correcting the local coupling--was not successful, and we discuss some possible reasons for this.
Date: January 1, 2004
Creator: Wolski, A.; /LBL, Berkeley; Nelson, J.; Ross, M.; Woodley, M.; /SLAC et al.
Partner: UNT Libraries Government Documents Department

Analysis of KEK-ATF Optics And Coupling Using Orbit Response Matrix Analysis

Description: LOCO is a code for analysis of the linear optics in a storage ring based on the closed orbit response to steering magnets. The analysis provides information on focusing errors, BPM gain and rotation errors, and local coupling. Here, we report the results of an application of LOCO to the KEK-ATF. Although the analysis appears to have provided useful information on the optics of the machine, it appears that one of the main aims of the study--to reduce the vertical emittance by correcting the local coupling--was not successful, and we discuss some possible reasons for this.
Date: October 13, 2006
Creator: Wolski, A.; /LBL, Berkeley; Nelson, J.; Ross, M.; Woodley, M.; /SLAC et al.
Partner: UNT Libraries Government Documents Department

Science & Technology Review November 2007

Description: This month's issue has the following articles: (1) Simulating the Electromagnetic World--Commentary by Steven R. Patterson; (2) A Code to Model Electromagnetic Phenomena--EMSolve, a Livermore supercomputer code that simulates electromagnetic fields, is helping advance a wide range of research efforts; (3) Characterizing Virulent Pathogens--Livermore researchers are developing multiplexed assays for rapid detection of pathogens; (4) Imaging at the Atomic Level--A powerful new electron microscope at the Laboratory is resolving materials at the atomic level for the first time; (5) Scientists without Borders--Livermore scientists lend their expertise on peaceful nuclear applications to their counterparts in other countries; and (6) Probing Deep into the Nucleus--Edward Teller's contributions to the fast-growing fields of nuclear and particle physics were part of a physics golden age.
Date: October 16, 2007
Creator: Chinn, D J
Partner: UNT Libraries Government Documents Department

PitPro 1.1 User's Manual; Pit-tag to SURPH Data Translation Utility, Technical Manual 2003.

Description: This manual describes the use of Program PitPro to convert PIT-tag data files in PTAGIS (PIT Tag Information System, Pacific States Marine Fisheries Commission) to input files ready for survival analysis in Program SURPH 2.1. This utility converts the various PIT-tag detections at the multitude of detector coils within a juvenile bypass or at adult counting windows and ladders into capture histories. The capture histories indicate whether a tagged fish was detected, not detected, or detected and censored at the major hydroprojects in the Columbia Basin. A major update to this program is the inclusion of adult upstream detection histories. Adult detection histories include not only whether the fish was detected or not but also the year of detection for proper adult survival estimation. The SURPH program is a valuable tool for estimating survival and detection probabilities of fish migrating in the Snake and Columbia rivers. Using special input data files, SURPH computes reach-to-reach statistics for any release group passing a system of detection sites. However, PIT-tag data, as available from PTAGIS, comes in a form that is not ready for use as SURPH input. SURPH requires a capture history for each fish. A capture history consists of a series of fields, one for each detection site, that has a code for whether the fish was detected and returned to the river, detected and removed, or not detected. The data, as received from PTAGIS, has one line for each detection with information such as fish identification (id), detection date and time, number of coil hits and detector coil ids, etc. Because an individual fish may be detected at several coils within a detection site as well as at several detection sites, each fish is often represented by multiple lines in the PTAGIS data file. For the PTAGIS data to be ...
Date: July 1, 2003
Creator: Westhagen, Peter & Skalski, John
Partner: UNT Libraries Government Documents Department

Lattice Boltzmann Simulation Optimization on Leading Multicore Platforms

Description: We present an auto-tuning approach to optimize application performance on emerging multicore architectures. The methodology extends the idea of search-based performance optimizations, popular in linear algebra and FFT libraries, to application-specific computational kernels. Our work applies this strategy to a lattice Boltzmann application (LBMHD) that historically has made poor use of scalar microprocessors due to its complex data structures and memory access patterns. We explore one of the broadest sets of multicore architectures in the HPC literature, including the Intel Clovertown, AMD Opteron X2, Sun Niagara2, STI Cell, as well as the single core Intel Itanium2. Rather than hand-tuning LBMHD for each system, we develop a code generator that allows us identify a highly optimized version for each platform, while amortizing the human programming effort. Results show that our auto-tuned LBMHD application achieves up to a 14x improvement compared with the original code. Additionally, we present detailed analysis of each optimization, which reveal surprising hardware bottlenecks and software challenges for future multicore systems and applications.
Date: February 1, 2008
Creator: Williams, Samuel; Carter, Jonathan; Oliker, Leonid; Shalf, John & Yelick, Katherine
Partner: UNT Libraries Government Documents Department


Description: Certain longitudinal instabilities in the stretched bunches of the National Synchrotron Light Source Vacuum Ultra-Violet ring are described and simulated using a code for the integration of the Vlasov-Fokker-Planck equation (these proceedings). Results for the microwave instability driven by broadband impedance, instability driven by high-Q radio-frequency modes, and response functions in stretched bunches, are compared with measurements from the ring.
Date: June 18, 2001
Creator: TOWNE,N.
Partner: UNT Libraries Government Documents Department

Long-Term Simulation of Beam-Beam Effects in the Tevatron at Collision Energy

Description: The beam-beam effect is a significant source of nonlinearities in the Tevatron. We have developed a code which allows us to estimate its contribution to the finite lifetime of the anti-proton beam, both at collision and injection energy, by tracking realistic particle distribution for a high number of terms and extrapolating from the particle loss rate. We describe the physical modeling underlying the code and give benchmarking results.
Date: February 10, 2006
Creator: Kabel, A.C.; Cai, Y.; /SLAC; Sen, T. & /Fermilab
Partner: UNT Libraries Government Documents Department

Nuclear Forensics Attributing the Source of Spent Fuel Used in an RDD Event

Description: An RDD attack against the U.S. is something America needs to prepare against. If such an event occurs the ability to quickly identify the source of the radiological material used in an RDD would aid investigators in identifying the perpetrators. Spent fuel is one of the most dangerous possible radiological sources for an RDD. In this work, a forensics methodology was developed and implemented to attribute spent fuel to a source reactor. The specific attributes determined are the spent fuel burnup, age from discharge, reactor type, and initial fuel enrichment. It is shown that by analyzing the post-event material, these attributes can be determined with enough accuracy to be useful for investigators. The burnup can be found within a 5% accuracy, enrichment with a 2% accuracy, and age with a 10% accuracy. Reactor type can be determined if specific nuclides are measured. The methodology developed was implemented into a code call NEMASYS. NEMASYS is easy to use and it takes a minimum amount of time to learn its basic functions. It will process data within a few minutes and provide detailed information about the results and conclusions.
Date: June 1, 2005
Creator: Scott, M.R.
Partner: UNT Libraries Government Documents Department

Highly scalable linear solvers on thousands of processors.

Description: In this report we summarize research into new parallel algebraic multigrid (AMG) methods. We first provide a introduction to parallel AMG. We then discuss our research in parallel AMG algorithms for very large scale platforms. We detail significant improvements in the AMG setup phase to a matrix-matrix multiplication kernel. We present a smoothed aggregation AMG algorithm with fewer communication synchronization points, and discuss its links to domain decomposition methods. Finally, we discuss a multigrid smoothing technique that utilizes two message passing layers for use on multicore processors.
Date: September 1, 2009
Creator: Domino, Stefan Paul (Sandia National Laboratories, Albuquerque, NM); Karlin, Ian (University of Colorado at Boulder, Boulder, CO); Siefert, Christopher (Sandia National Laboratories, Albuquerque, NM); Hu, Jonathan Joseph; Robinson, Allen Conrad (Sandia National Laboratories, Albuquerque, NM) & Tuminaro, Raymond Stephen
Partner: UNT Libraries Government Documents Department

Automatic differentiation as a tool for sensitivity analysis of a convective storm in a 3-D cloud model

Description: The ADIFOR automatic differentiation tool is applied to a 3-D storm-scale meteorological model to generate a sensitivity-enhanced code capable of providing derivatives of all model output variables and related diagnostic (derived) parameters as a function of specified control parameters. The tangent linear approximation, applied to a deep convective storm by the first of its kind using a full-physics compressible model, is valid up to 50 min for a 1% water vapor perturbations. The result is very encouraging considering the highly nonlinear and discontinuous properties of solutions. The ADIFOR-generated code has provided valuable sensitivity information on storm dynamics. Especially, it is very efficient and useful for investigating how a perturbation inserted at earlier time propagates through the model variables at later times. However, it is computationally very expensive to be applied to the variational data assimilation, especially for 3-D meteorological models, which potentially have a large number of input variables.
Date: October 1996
Creator: Park, S. K.; Droegemeier, K. K. & Bischof, C. H.
Partner: UNT Libraries Government Documents Department

Finite element prediction of elastic strains in beryllium compact tension specimens

Description: Three-dimensional finite element (FE) calculations using ABAQUS version 5.5.9 were compared to neutron diffraction measurements of a loaded, pre-cracked beryllium compact tension (CT) specimens. The objective was to validate the FE results with the experimental {open_quotes}elastic strain{close_quotes} measurements. Then the FE calculations could be used to study residual stress and other aspects of these problems in the unloaded state and the crack tip stress in the loaded state which is hard to measure experimentally. A graded FE mesh was focused on the regions containing high strain gradients, the smallest elements were approximately 0.5 mm x 0.5 mm x 0.4 mm. A standard 20-node brick element model was complemented by a model with 1/4-point elements at the crack tip. Since the neutron diffraction measurements provided a volume average of approximately a cube of edge 3.0 mm, various averaging (or integrating) techniques were used on the FE results. Several integration schemes showed good agreement with the experimental results.
Date: May 1, 1997
Creator: Guerra, F.; Varma, R. & Bourke, M.
Partner: UNT Libraries Government Documents Department

Automatic TLI recognition system, programmer`s guide

Description: This report describes the software of an automatic target recognition system (version 14), from a programmer`s point of view. The intent is to provide information that will help people who wish to modify the software. In separate volumes are a general description of the ATR system, Automatic TLI Recognition System, General Description, and a user`s manual, Automatic TLI Recognition System, User`s Guide. 2 refs.
Date: February 1, 1997
Creator: Lassahn, G.D.
Partner: UNT Libraries Government Documents Department

ACME: Algorithms for Contact in a Multiphysics Environment API Version 1.3

Description: An effort is underway at Sandia National Laboratories to develop a library of algorithms to search for potential interactions between surfaces represented by analytic and discretized topological entities. This effort is also developing algorithms to determine forces due to these interactions for transient dynamics applications. This document describes the Application Programming Interface (API) for the ACME (Algorithms for Contact in a Multiphysics Environment) library.
Date: May 1, 2003
Partner: UNT Libraries Government Documents Department

Stability analysis of a variable-speed wind turbine

Description: This paper examines the elastomechanical stability of a four-bladed wind turbine over a specific rotor speed range. Stability modes, frequencies, and dampings are extracted using a specialized modal processor developed at NREL that post-processes the response data generated by the ADAMS simulation code. The processor can analyze a turbine with an arbitrary number of rotor blades and offers a novel capability of isolating stability modes that become locked at a single frequency. Results indicate that over a certain rotor speed range, the tower lateral mode and the rotor regressive in-plane mode coalesce, resulting in a self-excited instability. Additional results show the effect of tower and nacelle parameters on the stability boundaries.
Date: October 1, 1996
Creator: Bir, G.S.; Wright, A.D. & Butterfield, C.P.
Partner: UNT Libraries Government Documents Department

Verification of AXAIRQ

Description: AXAIR89Q, designed to determine downwind doses following acute atmospheric releases at SRS, has been improved; the new version is AXAIRQ. Improvements include deposition option, new diffusion coefficients, ability to calculate 95% dose at user selected distances, and user-input mixing height. Other improvements also have been made to the format of the output. The user has the option to select the new features or operate the code as AXAIR89Q.
Date: October 1, 1995
Creator: Simpkins, A. A.
Partner: UNT Libraries Government Documents Department

MC&A software assistance to Ukraine

Description: AIMAS (Automated Inventory/Material Accounting System) is a PC-based application that is being developed as part of the U.S. assistance program to Ukraine in Nuclear Material Protection, Control, and Accounting (MPC&A). The AIMAS software prototype was designed to provide a starting point for joint U.S./Ukraine system development. Computer systems with AIMAS prototypes have been installed at Kiev Institute of Nuclear Research (KINR), Sevastopol Institute of Nuclear Energy & Industry (SINEI) and the Ministry of Environmental Protection and Nuclear Safety database management system (RDBMS) and application development environment. It has been designed to be highly flexible and configurable, and to support a wide range of computing infrastructure needs and facility requirements. AIMAS functions include basic physical inventory tracking, transaction histories, reporting, and system administration functions (system configuration and security). Security measures include multilevel password access controls, all transactions logged with the user ID, and system administration controls. Interfaces to external modules are being designed to provide nuclear fuel burn-up adjustment and barcode scanning capabilities for physical inventory taking. 1 ref.
Date: September 1, 1997
Creator: Ewing, T.; McWilliams, C. & Olson, A.
Partner: UNT Libraries Government Documents Department