Center for Computing Research (CCR)
Center for Computing Research (CCR)

Publications

Results 11051–11100 of 12,511

Search results

Jump to search filters

Yucca Mountain licensing support network archive assistant

Dunlavy, Daniel M.; Basilico, Justin D.; Verzi, Stephen J.; Bauer, Travis L.

This report describes the Licensing Support Network (LSN) Assistant--a set of tools for categorizing e-mail messages and documents, and investigating and correcting existing archives of categorized e-mail messages and documents. The two main tools in the LSN Assistant are the LSN Archive Assistant (LSNAA) tool for recategorizing manually labeled e-mail messages and documents and the LSN Realtime Assistant (LSNRA) tool for categorizing new e-mail messages and documents. This report focuses on the LSNAA tool. There are two main components of the LSNAA tool. The first is the Sandia Categorization Framework, which is responsible for providing categorizations for documents in an archive and storing them in an appropriate Categorization Database. The second is the actual user interface, which primarily interacts with the Categorization Database, providing a way for finding and correcting categorizations errors in the database. A procedure for applying the LSNAA tool and an example use case of the LSNAA tool applied to a set of e-mail messages are provided. Performance results of the categorization model designed for this example use case are presented.

More Details
TYPE SAND Report YEAR 2008
DOIOSTI

Sustaining knowledge in the neutron generator community and benchmarking study

Huff, Tameka B.; Turgeon, Jennifer; Baldonado, Esther; Stubblefield, William A.; Kennedy, Bryan C.; Saba, Anthony W.

In 2004, the Responsive Neutron Generator Product Deployment department embarked upon a partnership with the Systems Engineering and Analysis knowledge management (KM) team to develop knowledge management systems for the neutron generator (NG) community. This partnership continues today. The most recent challenge was to improve the current KM system (KMS) development approach by identifying a process that will allow staff members to capture knowledge as they learn it. This 'as-you-go' approach will lead to a sustainable KM process for the NG community. This paper presents a historical overview of NG KMSs, as well as research conducted to move toward sustainable KM.

More Details
TYPE SAND Report YEAR 2008
DOIOSTI

Dissipation-induced heteroclinic orbits in tippe tops

Proposed for publication in SIAM Review.

Romero, Louis

This paper demonstrates that the conditions for the existence of a dissipation-induced heteroclinic orbit between the inverted and noninverted states of a tippe top are determined by a complex version of the equations for a simple harmonic oscillator: the modified Maxwell-Bloch equations. A standard linear analysis reveals that the modified Maxwell-Bloch equations describe the spectral instability of the noninverted state and Lyapunov stability of the inverted state. Standard nonlinear analysis based on the energy momentum method gives necessary and sufficient conditions for the existence of a dissipation-induced connecting orbit between these relative equilibria.

More Details
TYPE Journal Article YEAR 2008
OSTI

Parallel job scheduling policies to improve fairness : a case study

Leung, Vitus J.

Balancing fairness, user performance, and system performance is a critical concern when developing and installing parallel schedulers. Sandia uses a customized scheduler to manage many of their parallel machines. A primary function of the scheduler is to ensure that the machines have good utilization and that users are treated in a 'fair' manner. A separate compute process allocator (CPA) ensures that the jobs on the machines are not too fragmented in order to maximize throughput. Until recently, there has been no established technique to measure the fairness of parallel job schedulers. This paper introduces a 'hybrid' fairness metric that is similar to recently proposed metrics. The metric uses the Sandia version of a 'fairshare' queuing priority as the basis for fairness. The hybrid fairness metric is used to evaluate a Sandia workload. Using these results, multiple scheduling strategies are introduced to improve performance while satisfying user and system performance constraints.

More Details
TYPE SAND Report YEAR 2008
DOIOSTI

ALEGRA: An arbitrary Lagrangian-Eulerian multimaterial, multiphysics code

46th AIAA Aerospace Sciences Meeting and Exhibit

Robinson, Allen C.; Brunner, Thomas A.; Carroll, Susan; Richarddrake; Garasi, Christopher J.; Gardiner, Thomas; Haill, Thomas; Hanshaw, Heath; Hensinger, David; Labreche, Duane; Lemke, Raymond; Love, Edward; Luchini, Christopher; Mosso, Stewart; Niederhaus, John; Ober, Curtis C.; Petney, Sharon; Rider, William J.; Scovazzi, Guglielmo; Strack, O.E.; Summers, Randall; Trucano, Timothy; Weirs, V.G.; Wong, Michael; Voth, Thomas

ALEGRA is an arbitrary Lagrangian-Eulerian (multiphysics) computer code developed at Sandia National Laboratories since 1990. The code contains a variety of physics options including magnetics, radiation, and multimaterial flow. The code has been developed for nearly two decades, but recent work has dramatically improved the code's accuracy and robustness. These improvements include techniques applied to the basic Lagrangian differencing, artificial viscosity and the remap step of the method including an important improvement in the basic conservation of energy in the scheme. We will discuss the various algorithmic improvements and their impact on the results for important applications. Included in these applications are magnetic implosions, ceramic fracture modeling, and electromagnetic launch. Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc.

More Details
TYPE Conference YEAR 2008
ScopusOSTI
Results 11051–11100 of 12,511
Results 11051–11100 of 12,511
Top