207225786
Genetic Algorithms: A Practitioner's View
The feature article by Colin Reeves provides a useful introduction to genetic algorithms (GAs) for the operations researcher. In this commentary, I will elaborate on several of Reeves' points and introduce some others. My experience with GAs is as a practitioner and software developer, and it is from this perspective that I will comment on Reeves' article.
17053048
Performance Testing of a Parallel Multiblock CFD Solver
A distributed-memory version of the OVERFLOW computational fluid dynamics code was evaluated on several parallel systems and compared with other approaches using test cases provided by the NASA-Boeing High-Speed Civil Transport program. A principal goal was to develop partitioning and load-balancing strategies that led to a reduction in computation time. We found multipartitioning, in which the aspect ratio of the multipartition is close to the aspect ratio of the grid zone, offered the best performance. The (uniprocessor) performance of the CRAY vector systems was superior to all other systems tested. However, the distributed-memory version when run on an SGI Origin system offers a price performance advantage over the CRAY vector systems.Performance on personal computer systems is promising but faces several hurdles.
20665084
Parallel performance of two applications in the Boeing high performance computing benchmark suite
Abstract We describe our work to evaluate the performance of the parallel versions of two floating-point-intensive engineering applications from Boeing's high performance computing benchmark suite (BHPCBS) on emerging RISC parallel systems and PC clusters. The first application is a computational fluid dynamics (CFD) code, OVERFLOW, developed by NASA and used by Boeing for analysis and design of advanced aircraft. The second application is a prototype of a computational electromagnetics (CEM) code, developed by Boeing and used for radar cross-section studies. The distributed memory parallel versions of both applications use the message passing interface (MPI) standard for message passing. The goal of our work was to determine whether RISC parallel systems and PC clusters, which offer high performance at low cost, may be able to meet Boeing's computing requirements in the future. We describe the test environments for the studies, discuss parallelization issues and strategies and present performance data for the two applications.
29157947
Massively parallel computation of conservation laws
Abstract We present a new method for computing solutions of conservation laws based on the use of cellular automata with the method of characteristics. The method exploits the high degree of parallelism available with cellular automata and retains important features of the method of characteristics. It yields high numerical accuracy and extends naturally to adaptive meshes and domain decomposition methods for perturbed conservation laws. We describe the method and its implementation for a Dirichlet problem with a single conservation law for the one-dimensional case. Numerical results for the one-dimensional law with the classical Burgers nonlinearity or the Buckley-Leverett equation show good numerical accuracy outside the neighborhood of the shocks. The error in the area of the shocks is of the order of the mesh size. The algorithm is well suited for execution on both massively parallel computers and vector machines. We present timing results for an Alliant FX/8, Connection Machine Model 2, and CRAY X-MP.
15912029
A butterfly subdivision scheme for surface interpolation with tension control
A new interpolatory subdivision scheme for surface design is presented. The new scheme is designed for a general triangulation of control points and has a tension parameter that provides design flexibility. The resulting limit surface is C1 for a specified range of the tension parameter, with a few exceptions. Application of the butterfly scheme and the role of the tension parameter are demonstrated by several examples.
15239156
Application of a hybrid genetic algorithm to airline crew scheduling
This paper discusses the development and application of a hybrid genetic algorithm to airline crew scheduling problems. The hybrid algorithm consists of a steady-state genetic algorithm and a local search heuristic. The hybrid algorithm was tested on a set of 40 real-world problems. It found the optimal solution for half the problems, and good solutions for 9 others. The results were compared to those obtained with branch-and-cut and branch-and-bound algorithms. The branch-and-cut algorithm was significantly more successful than the hybrid algorithm, and the branch-and-bound algorithm slightly better.
9657478
Computational Electromagnetics and Parallel Dense Matrix Computations
We present computational results using CORAL, a parallel, three-dimensional, nonlinear magnetostatic code based on a volume integral equation formulation. A key feature of CORAL is the ability to solve, in parallel, the large, dense systems of linear equations that are inherent in the use of integral equation methods. Using the Chameleon and PSLES libraries ensures portability and access to the latest linear algebra solution technology.
16053840
Parallel computation of three-dimensional nonlinear magnetostatic problems
We describe a general-purpose parallel electromagnetic code for computing accurate solutions to large computationally demanding, 3D, nonlinear magnetostatic problems. The code, CORAL, is based on a volume integral equation formulation. Using an IBM SP parallel computer and iterative solution methods, we successfully solved the dense linear systems inherent in such formulations. A key component of our work was the use of the PETSc library, which provides parallel portability and access to the latest linear algebra solution technology.