NASA Scientific and Technical Aerospace Reports

20040050359 Lawrence Livermore National Lab., Livermore, CA
PVODE Trio: PVODE, KINSOL, and IDA
Hindmarsh, A. C.; Brown, P.; Grant, K.; Lee, S.; Serban, R.; Oct. 01, 2001; 34 pp.; In English
Report No.(s): DE2004-15006305; UCRL-JC-145579; No Copyright; Avail: Department of Energy Information Bridge
No abstract available
Data Transmission; Computer Programs
20040050368 Lawrence Livermore National Lab., Livermore, CA
Feedback From Video From Virtual Reality Navigation
Tsap, L. V.; Oct. 27, 2000; 10 pp.; In English
Report No.(s): DE2004-15006285; UCRL-JC-141131; No Copyright; Avail: Department of Energy Information Bridge
Important preconditions for wide acceptance of virtual reality (VR) systems include their comfort, ease and naturalness
to use. Most existing trackers super from discomfort-related issues. For example, body-based trackers (hand controllers,
joysticks, helmet attachments, etc.) restrict spontaneity and naturalness of motion, while ground-based devices (e.g., hand
controllers) limit the workspace by literally binding an operator to the ground. There are similar problems with controls. This
paper describes using real-time video with registered depth information (from a commercially available camera) for virtual
reality navigation. Camera-based setup can replace cumbersome trackers. The method includes selective depth processing for
increased speed, and a robust skin-color segmentation for accounting illumination variations.
NTIS
Feedback; Real Time Operation; Information Systems
20040050382 Lawrence Livermore National Lab., Livermore, CA
Handling Irreducible Loops: Optimized Node Splitting vs DJ-Graphs
Unger, S.; Mueller, F.; May 21, 2001; 18 pp.; In English
Report No.(s): DE2004-15006265; UCRL-JC-143798-R1; No Copyright; Avail: Department of Energy Information Bridge
This paper addresses the question of how to handle irreducible regions during optimization, which has become even more
relevant for contemporary processors since recent VLIW-like architectures highly rely on instruction scheduling. The
contributions of this paper are twofold. First, a method of optimized node splitting to transform irreducible regions of control
flow into reducible regions is derived. This method is superior to approaches previously published since it reduces the number
of replicated nodes by comparison. Second, three methods that handle regions of irreducible control flow are evaluated with
respect to their impact on compiler optimizations: traditional and optimized node splitting as well as loop analysis through DJ
graphs. Measurements show improvements of 1-40% for these methods of handling irreducible loop over the unoptimized
case.
NTIS
Loops; Optimization; Education; Compilers
20040050392 Royal Inst. of Tech., Stockholm, Sweden
Elliptic Systems of Partial Differential Equations Generated by Vector Vields Which Degenerate at the Boundary of the
Domain
Dzhuraev, A.; Jun. 2003; 24 pp.; In English
Report No.(s): PB2004-102647; TRITA-MAT-2003-12; No Copyright; Avail: CASI; A03, Hardcopy
In this paper we study some elliptic systems of partial differential equations in a bounded domain generated by a vector
field which degenerates on the boundary of the domain.
NTIS
Elliptic Differential Equations; Boundaries
20040050408, Department of Energy, Tulsa, OK, USA
New Generation Chemical Flooding Simulator. Semi-Annual Report for the Period September 1, 2001-February 28,
2002
Pope, G. A.; Sepehrnoori, K.; Delshad, M.; 2002; 68 pp.; In English
Report No.(s): DE2004-820951; No Copyright; Avail: Department of Energy Information Bridge
The premise of this research is that a general-purpose reservoir simulator for several improved oil recovery processes can
and should be developed so that high-resolution simulations of a variety of very large and difficult problems can be achieved
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