Papers & Reports 2004

A modular framework for aerodynamic optimization of complex geometries is developed. By working directly with a parametric CAD system, complex-geometry models are modified and tessellated in an automatic fashion.
CAD-Based Aerodynamic Design of Complex Configurations Using a Cartesian Method,NAS Technical Report, NAS-04-001, March 2004.

This paper presents a variety of novel uses of space-filling curves (SFCs) for Cartesian mesh methods in CFD. While these techniques will be demonstrated using non-body-fitted Cartesian meshes, many are applicable on general body-fitted meshes – both structured and unstructured.
Applications of Space-Filling Curves to Cartesian Methods for CFD,NAS Technical Report, NAS-04-002, March 2004.

We study the linear intersubband absorption spectra of a 15nm InAs quantum well using the intersubband semiconductor Bloch equations with a three-subband model and a constant dephasing rate. We demonstrate the evolution of intersubband absorption spectral line shape as a function of temperature and electron density.
Microscopic Theory and Simulation of Quantum-Well Intersubband Absorption: A Three-Subband Model,NAS Technical Report, NAS-04-003, March 2004.

This paper describes the design and implementation of the IPG Execution Service that reliably executes complex jobs on a computational grid. Our Execution Service is part of the IPG service architecture whose goal is to support location-independent computing. I
An Execution Service for Grid Computing,NAS Technical Report, NAS-04-004, April 2004.

The NAS Grid Benchmarks (NGB) are a collection of synthetic distributed applications designed to rate the performance and functionality of computational grids. We compare several implementations of the NGB to determine programmability and efficiency of NASA’s Information Power Grid (IPG), whose services are mostly based on the Globus Toolkit.
Evaluating the Information Power Grid using the NAS Grid Benchmarks,NAS Technical Report, NAS-04-005, May 2004.

We present a complete specification of a new benchmark for measuring the performance of modern computer systems when solving scientific problems featuring irregular, dynamic memory accesses. It complements the existing NAS Parallel Benchmark suite.
Unstructured Adaptive (UA) NAS Parallel Benchmark, Version 1.0,NAS Technical Report, NAS-04-006, July 2004.

This paper suggests visualization tools to allow scientists to rapidly explore, interpret and discover characteristic distributions within the entire spatial field. The major contribution of this work is a paradigm shift that allows ecologists to think of and analyze their data in terms of full distributions, including their modality and shape, not just summary statistics.
Visualizing Distributions from Multi-Return Lidar Data to Understand Forest Structure,NAS Technical Report, NAS-04-007, June 2004.

We investigate the density-gradient (DG) transport model for efficient multi-dimensional simulation of quantum confinement effects in advanced MOS devices. The formulation of the DG model is described as a quantum correction to the classical drift-diffusion model.
Efficient Multi-Dimensional Simulation of Quantum Confinement Effects in Advanced MOS Devices,NAS Technical Report, NAS-04-008, August 2004.

This paper addresses the components required for a satellite-based communications system, applications, technology trends, orbits, and spectrum, and hopefully will afford the reader an end-to-end picture of this important technology.
Introduction to Satellite Communications Technology for NREN,NAS Technical Report, NAS-04-009, August 2004.

In this paper, we demonstrate that knowledge of dependence information and OpenMP are no longer essential to produce efficient parallel code with the Expert Assistant. It is hoped that this will enable a far wider audience to use the tools and subsequently, exploit the benefits of large parallel systems.
The ParaWise Expert Assistant - Widening Accessibility to Efficient and Scalable Tool Generated OpenMP Code,NAS Technical Report, NAS-04-010, August 2004.

This paper will provide an overview of IP telephony and wireless LAN concepts and examine VoIP applicability for planetary exploration. The use of VoIP at the Mars Desert Research Station (MDRS) will be evaluated.
IP Telephony for Interplanetary Exploration,NAS Technical Report, NAS-04-011, September 2004.

Data movement across computer memory hierarchy and across hosts of distributed systems is known to be a limiting factor for applications processing large data sets. We use the Data Cube Operator on an Arithmetic Data Set, called ADC, to benchmark computer capability to handle large datasets
Benchmarking Memory Performance with the Data Cube Operator,NAS Technical Report, NAS-04-013, September 29, 2004.

This paper helps the reader understand the characteristics of the Cray X1 vector supercomputer system, and provides hints and information to enable the reader to port codes to the system. It provides a comparison between the basic performance of the X1 platform and other platforms available at NASA Ames Research Center.
Understanding the Cray X1 System,NAS Technical Report, NAS-04-014, December 2004.

A modular process for performing general parametric studies about an aerodynamic configuration using a Cartesian method is described. A novel part of this process is the automatic handling of general control surfaces deflections based upon simple, userspecified inputs.
Automated Parameter Studies Using a Cartesian Method,NAS Technical Report, NAS-04-015, December 2004.

Recent advances in supercomputers and highly scalable quantum chemistry software render computational chemistry methods a viable means of providing chemistry data for aerothermal analysis at a specific level of confidence. Four examples of first principles quantum chemistry calculations will be presented.
Chemistry Modeling for Aerothermodynamics and TPS,NAS Technical Report, NAS-04-016, December 2004.

Planning complex missions requires a number of programs to be executed in concert. The Application Navigation System (ANS), developed in the NASA Advanced Supercomputing Division, can execute many interdependent programs in a distributed environment
Optimizing Mars Airplane Trajectory with the Application Navigation System,NAS Technical Report, NAS-04-017, December 2004.