Engineering topics

Parks, John W.

Publications and source records attributed to Parks, John W..

8 records

NASA NTRS2003

Developing an Open Source Option for NASA Software

We present arguments in favor of developing an Open Source option for NASA software; in particular we discuss how Open Source is compatible with NASA's mission. We compare and contrast several of the leading Open Source licenses, and propose one - the Mozilla license - for use by NASA. We also address some of the related issues for NASA with respect to Open Source. In particular, we discuss some of the elements in the External Release of NASA Software document (NPG 2210.1A) that will likely have to be changed in order to make Open Source a reality withm the agency.

Moran, Patrick J.↗

NASA NTRS2002

Tensile Yielding of Multi-Wall Carbon Nanotube

The tensile yielding of multiwall carbon nanotubes (MWCNTs) has been studied using Molecular Dynamics simulations and a Transition State Theory based model. We find a strong dependence of the yielding on the strain rate. A critical strain rate has been predicted above/below which yielding strain of a MWCNT is larger/smaller than that of the corresponding single-wall carbon nanotubes. At experimentally feasible strain rate of 1% /hour and T = 300K, the yield strain of a MWCNT is estimated to be about 3-4 % higher than that of an equivalent SWCNT (Single Wall Carbon Nanotube), in good agreement with recent experimental observations.

Wei, Chenyu↗

NASA NTRS2002

Data Access Technology Workshop Position Paper

This paper addresses the seven questions that were requested of attendees prior to attending the Data Access Technology Workshop that is scheduled for October 8-9,2002. Each of the questions is addressed in the following seven sections. The seven questions are: 1) What emerging technologies do you feel would best enhance user access to EOSDIS data and why? 2) How do you envision these technologies being used? How should they be used in combination with each other? 3) Can technologies be readily leveraged to achieve these results today? If not, when do you think they will be viable? 4) What investments do you think EOSDIS should make in these technologies today? Over the next 5 years? 5) What are reasonable cost expectations for leveraging these technologies as you've suggested? 6) What are the anticipated impacts on end users if these technologies are deployed, including investments required? 7) What unique researcher data access requirements need to be supported?

Hinke, Thomas H.↗

NASA NTRS2002

A Data Miner for the Information Power Grid

Grid Miner (GM) is one of the early data mining applications developed by NASA to help users obtain information from the Information Power Grid (IPG). Topics cover include: benefits of data mining, potential use of grids in data mining activities, an overview of the GM application, and a brief review of GM architecture and implementation issues. The current status of the GM system is also discussed.

Hinke, Thomas H.↗

NASA NTRS2002

NASA Advanced Supercomputing (NAS) User Services Group

This viewgraph presentation provides an overview of NAS (NASA Advanced Supercomputing), its goals, and its mainframe computer assets. Also covered are its functions, including systems monitoring and technical support.

Pandori, John↗

NASA NTRS2002

Tera Scale Systems and Applications

This presentation discusses NASA's efforts to develop tera scale systems designed to push the envelope of supercomputing research. Topics cover include: NASA's existing supercomputing facilities and capabilities, NASA's computational challenges in developing these systems, development of production supercomputer, and potential research projects which could benefit from these types of systems.

Niggley, Chuck↗

NASA NTRS2002

Waves in Turbulent Stably Stratified Shear Flow

Two approaches for the identification of internal gravity waves in sheared and unsheared homogeneous stratified turbulence are investigated. First, the phase angle between the vertical velocity and density fluctuations is considered. It was found, however, that a continuous distribution of the phase angle is present in weakly and strongly stratified flow. Second, a projection onto the solution of the linearized inviscid equations of motion of unsheared stratified flow is investigated. It was found that a solution of the fully nonlinear viscous Navier-Stokes equations can be represented by the linearized inviscid solution. The projection yields a decomposition into vertical wave modes and horizontal vortical modes.

Jacobitz, F. G.↗

NASA NTRS2002

Designing Adaptive Low Dissipative High Order Schemes

Proper control of the numerical dissipation/filter to accurately resolve all relevant multiscales of complex flow problems while still maintaining nonlinear stability and efficiency for long-time numerical integrations poses a great challenge to the design of numerical methods. The required type and amount of numerical dissipation/filter are not only physical problem dependent, but also vary from one flow region to another. This is particularly true for unsteady high-speed shock/shear/boundary-layer/turbulence/acoustics interactions and/or combustion problems since the dynamics of the nonlinear effect of these flows are not well-understood. Even with extensive grid refinement, it is of paramount importance to have proper control on the type and amount of numerical dissipation/filter in regions where it is needed.

Yee, H. C.↗