Mesh independent convergence of the modified inexact Newton method for a second order nonlinear problem (open access)

Mesh independent convergence of the modified inexact Newton method for a second order nonlinear problem

In this paper, we consider an inexact Newton method applied to a second order nonlinear problem with higher order nonlinearities. We provide conditions under which the method has a mesh-independent rate of convergence. To do this, we are required to first, set up the problem on a scale of Hilbert spaces and second, to devise a special iterative technique which converges in a higher than first order Sobolev norm. We show that the linear (Jacobian) system solved in Newton's method can be replaced with one iterative step provided that the initial nonlinear iterate is accurate enough. The closeness criteria can be taken independent of the mesh size. Finally, the results of numerical experiments are given to support the theory.
Date: September 20, 2004
Creator: Kim, T; Pasciak, J E & Vassilevski, P S
System: The UNT Digital Library
The Mechanical and Thermal Design for the MICE Coupling SolenoidMagnet (open access)

The Mechanical and Thermal Design for the MICE Coupling SolenoidMagnet

The MICE coupling solenoids surround the RF cavities that are used to increase the longitudinal momentum of the muon beam that is being cooled within MICE. The coupling solenoids will have a warm-bore diameter of 1394 mm. This is the warm bore that is around the 200 MHz RF cavities. The coupling solenoid is a single superconducting coil fabricated from a copper matrix Nb-Ti conductor originally designed for MRI magnets. A single coupling magnet is designed so that it can be cooled with a single 1.5 W (at 4.2 K) cooler. The MICE cooling channel has two of these solenoids, which will be hooked together in series, for a magnet circuit with a total stored-energy of the order of 12.8 MJ. Quench protection for the coupling coils is discussed. This report also presents the mechanical and thermal design parameters for this magnet, including the results of finite element calculations of mechanical forces and heat flow in the magnet cold mass.
Date: September 20, 2004
Creator: Green, M.A.; Yang, S.Q.; Bravar, U.; Lau, W.; Li, D.; Strauss,B.P. et al.
System: The UNT Digital Library
Reconstruction Of Regulatory And Metabolic Pathways InMetal-Reducing delta-Proteobacteria (open access)

Reconstruction Of Regulatory And Metabolic Pathways InMetal-Reducing delta-Proteobacteria

Relatively little is known about the genetic basis for the unique physiology of metal-reducing genera in the delta subgroup of the proteobacteria. The recent availability of complete finished or draft-quality genome sequences for seven representatives allowed us to investigate the genetic and regulatory factors in a number of key pathways involved in the biosynthesis of building blocks and cofactors, metal-ion homeostasis, stress response, and energy metabolism using a combination of regulatory sequence detection and analysis of genomic context. In the genomes of delta-proteobacteria, we identified candidate binding sites for four regulators of known specificity (BirA, CooA, HrcA,sigma-32), four types of metabolite-binding riboswitches (RFN-, THI-,B12-elements and S-box), and new binding sites for the FUR, ModE, NikR,PerR, and ZUR transcription factors, as well as for the previously uncharacterized factors HcpR and LysX. After reconstruction of the corresponding metabolic pathways and regulatory interactions, we identified possible functions for a large number of previously uncharacterized genes covering a wide range of cellular functions. Phylogenetically diverse delta-proteobacteria appear to have homologous regulatory components. This study for the first time demonstrates the adaptability of the comparative genomic approach to de novo reconstruction of a regulatory network in a poorly studied taxonomic group of bacteria. Recent efforts …
Date: September 20, 2004
Creator: Rodionov, Dmitry A.; Dubchak, Inna; Arkin, Adam; Alm, Eric & Gelfand,Mikhail S.
System: The UNT Digital Library
Actinide Cross Section Evaluations (open access)

Actinide Cross Section Evaluations

The Livermore Computational Nuclear Physics group is charged with producing updated neutron incident cross section evaluations for all the actinides in the coming year, concentrating on neutron induced fission, neutron capture and (n,2n) cross sections. We attack this daunting task either by adopting other recent evaluations or by performing our own. Owing to the large number of nuclei involved, we seek to automate this process as much as possible. For this purpose, we have developed a series of computer codes: x41, an interface to the EXFOR database, fete, a code that translates ENDF/B formatted evaluations into a computationally convenient form, and da{_}fit, a fitting code that takes all relevant EXFOR data for a reaction or set of reactions and performs a generalized least square fit to them, subject to various constraints and other prior information.
Date: September 20, 2004
Creator: Brown, D. A.; Loyola, B. & McNabb, D.
System: The UNT Digital Library
A Computational and Experimental Investigation of Violence in a Thermal Explosion Test (open access)

A Computational and Experimental Investigation of Violence in a Thermal Explosion Test

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Date: September 20, 2004
Creator: Yoh, J.; McClelland, M. & Maienschein, J.
System: The UNT Digital Library
A Survey of High-Quality Computational Libraries and their Impactin Science and Engineering Applications (open access)

A Survey of High-Quality Computational Libraries and their Impactin Science and Engineering Applications

Recently, a number of important scientific and engineering problems have been successfully studied and solved by means of computational modeling and simulation. Many of these computational models and simulations benefited from the use of available software tools and libraries to achieve high performance and portability. In this article, we present a reference matrix of the performance of robust, reliable and widely used tools mapped to scientific and engineering applications that use them. We aim at regularly maintaining and disseminating this matrix to the computational science community. This matrix will contain information on state-of-the-art computational tools, their applications and their use.
Date: September 20, 2004
Creator: Drummond, L. A.; Hernandez, V.; Marques, O.; Roman, J. E. & Vidal, V.
System: The UNT Digital Library