Publications

Results 2426–2450 of 2,510

Search results

Jump to search filters

Toward Interactive Scenario Analysis and Exploration

Gayle, Thomas; Summers, Kenneth L.; Jungels, John; Bays, Nathan R.

As Modeling and Simulation (M&S) tools have matured, their applicability and importance have increased across many national security challenges. In particular, they provide a way to test how something may behave without the need to do real world testing. However, current and future changes across several factors including capabilities, policy, and funding are driving a need for rapid response or evaluation in ways that many M&S tools cannot address. Issues around large data, computational requirements, delivery mechanisms, and analyst involvement already exist and pose significant challenges. Furthermore, rising expectations, rising input complexity, and increasing depth of analysis will only increase the difficulty of these challenges. In this study we examine whether innovations in M&S software coupled with advances in ''cloud'' computing and ''big-data'' methodologies can overcome many of these challenges. In particular, we propose a simple, horizontally-scalable distributed computing environment that could provide the foundation (i.e. ''cloud'') for next-generation M&S-based applications based on the notion of ''parallel multi-simulation''. In our context, the goal of parallel multi- simulation is to consider as many simultaneous paths of execution as possible. Therefore, with sufficient resources, the complexity is dominated by the cost of single scenario runs as opposed to the number of runs required. We show the feasibility of this architecture through a stable prototype implementation coupled with the Umbra Simulation Framework [6]. Finally, we highlight the utility through multiple novel analysis tools and by showing the performance improvement compared to existing tools.

More Details

Planarized arrays of aligned, untangled multiwall carbon nanotubes with Ohmic back contacts

Journal of Materials Research

Friedman, Caitlin A.R.; Limmer, S.J.; Howell, Stephen W.; Bays, Nathan R.; Siegal, Michael P.

Vertically aligned, untangled planarized arrays of multiwall carbon nanotubes (MWNTs) with Ohmic back contacts were grown in nanopore templates on arbitrary substrates. The templates were prepared by sputter depositing Nd-doped Al films onto W-coated substrates, followed by anodization to form an aluminum oxide nanopore array. The W underlayer helps eliminate the aluminum oxide barrier that typically occurs at the nanopore bottoms by instead forming a thin WO3 layer. The WO3 can be selectively etched to enable electrodeposition of Co catalysts with control over the Co site density. This led to control of the site density of MWNTs grown by thermal chemical vapor deposition, with W also serving as a back electrical contact. Ohmic contact to MWNTs was confirmed, even following ultrasonic cutting of the entire array to a uniform height.

More Details

Supplemental Information Source Document Waste Management

Bays, Nathan R.

This Supplemental Information Source Document for Waste Management was prepared in support of future analyses including those that may be performed as part of the Sandia National Laboratories, New Mexico (SNL/NM) Site-Wide Environmental Impact Statement. This document presents information about waste management practices at SNL/NM, including definitions, inventory data, and an overview of current activities.

More Details

Addressing Modeling Requirements for Radiation Heat Transfer

Tencer, John T.; Akau, Ron L.; Dobranich, Dean; Brown, Alexander L.; Dodd, Amanda B.; Bays, Nathan R.; Okusanya, Tolulope O.; Phinney, Leslie; Pierce, Flint

Thermal analysts address a wide variety of applications requiring the simulation of radiation heat transfer phenomena. There are gaps in the currently available modeling capabilities. Addressing these gaps would allow for the consideration of additional physics and increase confidence in simulation predictions. This document outlines a five year plan to address the current and future needs of the analyst community with regards to modeling radiation heat transfer processes. This plan represents a significant multi-year effort that must be supported on an ongoing basis.

More Details
Results 2426–2450 of 2,510
Results 2426–2450 of 2,510
Top