NASA Scientific and Technical Aerospace Reports

when the CAD entity can be mapped to a logical rectangle. Watertightness and geometric quality measures are maintained and
are consistent with the CAPRI default tessellator. These triangulations can match user specified criteria for chord-height
tolerance, neighbor triangle dihedral angle, and maximum triangle side length. This discrete representation has hooks back to
the owning geometry and therefore can be used in conjunction with these entities to allow for easy enhancement or
modification of the tessellation suitable for grid generation or other downstream applications.
Author
Triangulation; Computer Aided Design
62
COMPUTER SYSTEMS
Includes computer networks and distributed processing systems. For information systems see 82 Documentation and Information
Science. For computer systems applied to specific applications, see the associated category.
20040045291 NASA Ames Research Center, Moffett Field, CA, USA
Use of the SCIRun PSE for Coupled Fluid-Structure Analysis
Cheung, Christopher; Guruswamy, Guru P.; December 15, 2003; 12 pp.; In English; Eleventh Conference on Parallel
Processing for Scientific Computing, February 2004, San Francisco, CA, USA; No Copyright; Avail: CASI; A03, Hardcopy
The objective of this paper is to investigate the use of Problem Solving Environments (PSE) for tightly coupled
fluid-structure control analysis of aerospace vehicles. The topics include: 1) Background; 2) The SCIRun PSE; 3) Projects
Done with SCIRun; 4) Research Procedures; 5) Installtion; 6) Installation Problems on NAS; 7) Module Development; 8)
Module Testing Framework; 9) Time Testing of SCIRun; and 10) Time Test Results. This paper is in viewgraph form.
CASI
Problem Solving; Programming Environments; Computerized Simulation; Supercomputers; Fluid Dynamics
20040046139 QSS Group, Inc., Moffett Field, CA, USA
Adding Assurance to Automatically Generated Code
Denney, Ewen; Fischer, Bernd; Schumann, Johann; [2004]; 3 pp.; In English; High Assurance Systems Engineering 2, 2 Mar.
2004, Tampa, FL, USA; No Copyright; Avail: CASI; A01, Hardcopy
Code to estimate position and attitude of a spacecraft or aircraft belongs to the most safety-critical parts of flight software.
The complex underlying mathematics and abundance of design details make it error-prone and reliable implementations costly.
AutoFilter is a program synthesis tool for the automatic generation of state estimation code from compact specifications. It
can automatically produce additional safety certificates which formally guarantee that each generated program individually
satisfies a set of important safety policies. These safety policies (e.g.. array-bounds, variable initialization) form a core of
properties which are essential for high-assurance software. Here we describe the AutoFilter system and its certificate generator
and compare our approach to the static analysis tool PolySpace.
Author
Automatic Control; State Estimation; Network Synthesis; Computer Systems Programs; Satellite Attitude Control;
Architecture (Computers)
20040050168 Lawrence Livermore National Lab., Livermore, CA
Performance of Neural Networks Methods in Intrusion Detection
Dao, V. N. P.; Vemuri, R.; Jul. 09, 2001; 12 pp.; In English
Report No.(s): DE2004-15005778; UCRL-JC-144473; No Copyright; Avail: Department of Energy Information Bridge
By accurately profiling the users via their unique attributes, it is possible to view the intrusion detection problem as a
classification of authorized users and intruders. This paper demonstrates that artificial neural network (ANN) techniques can
be used to solve this classification problem. Furthermore, the paper compares the performance of three neural networks
methods in classifying authorized users and intruders using synthetically generated data. The three methods are the gradient
descent back propagation (BP) with momentum, the conjugate gradient BP, and the quasi-Newton BP.
NTIS
Neural Nets; Performance; Intrusion Detection (Computers)
161