Browsing by Author "Baker, Chuck A."
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- Distributed Control Parallelism in Multidisciplinary Aircraft DesignKrasteva, Denitza T.; Watson, Layne T.; Baker, Chuck A.; Grossman, Bernard M.; Mason, William H.; Haftka, Raphael T. (Department of Computer Science, Virginia Polytechnic Institute & State University, 1998-09-01)Multidisciplinary design optimization (MDO) for large-scale engineering problems poses many challenges (e.g., the design of an efficient concurrent paradigm for global optimization based on disciplinary analyses, expensive computations over vast data sets, etc.) This work focuses on the application of distributed schemes for massively parallel architectures to MDO problems, as a tool for reducing computation time and solving larger problems. The specific problem considered here is configuraton optimization of a high speed civil transport (HSCT), and the efficient parallelization of the embedded paradigm for reasonable design space identification. Two distributed dynamic load balancing techniques (random polling and global round robin with message combining) and two necessary termination detection schemes (global task count and token passing) were implemented and evaluated in terms of effectiveness and scalability to large problem sizes and a thousand processors. The effect of certain parameters on execution time was also inspected. Empirical results demonstrated stable performance and effectiveness for all schemes, and the parametric study showed that the selected algorithmic parameters have a negligible effect on performance.
- A fully Distributed Parallel Global Search AlgorithmWatson, Layne T.; Baker, Chuck A. (Department of Computer Science, Virginia Polytechnic Institute & State University, 2000)The n-dimensional direct search algorithm DIRECT of Jones,Perttunen, and Stuckman has attracted recent attention from the multidisciplinary design optimization community. Since DIRECT only requires function values (or ranking)and balances global exploration with local refinement better than n-dimensional bisection, it is well suited to the noisy function values typical of realistic simulations. While not efficient for high accuracy optimization, DIRECT is appropriate for the sort of global design space exploration done in large scale engineering design. Direct and pattern search schemes have the potential to exploit massive parallelism, but efficient use of massively parallel machines is nontrivial to achieve. This paper presents a fully distribute control version of DIRECT that is designed for massively parallel (distribute memory architectures. Parallel results are presented for a multidisciplinary design optimization problem — configuration design of a high speed civil transport.
- HSCT Configuration Design Space Exploration Using Aerodynamic Response Surface ApproximationsBaker, Chuck A.; Grossman, Bernard M.; Haftka, Raphael T.; Mason, William H.; Watson, Layne T. (Department of Computer Science, Virginia Polytechnic Institute & State University, 1999-03-01)A method has been developed to generate and use polynomial approximations to the range and cruise drag components in a highly constrained, multidisciplinary design optimization of a High Speed Civil Transport configuration. The method improves optimization performance by eliminating the numerical noise present in the analyses through the use of response surface methodology. In our implementation, we fit quadratic polynomials within variable bounds to data gathered from a series of numerical analyses of different aircraft designs. Because the HSCT optimization process contains noise and suffers from a nonconvex design space even when noise is filtered out, multiple optimization runs are performed from different starting points with and without the response surface models in order to evaluate their effectiveness. It is shown that response surface methodology facilitates design space exploration, allowing improvements in terms of both convergence performance and computational effort when multiple starting points are required.
- Parallel Global Aircraft Configuration Design Space ExplorationBaker, Chuck A.; Watson, Layne T.; Grossman, Bernard M.; Mason, William H.; Haftka, Raphael T. (Department of Computer Science, Virginia Polytechnic Institute & State University, 2000)The preliminary design space exploration for large,interdisciplinary engineering problems is often a difficult and time-consuming task. General techniques are needed that efficiently and methodically search the design space. This work focuses on the use of parallel load balancing techniques integrated with a global optimizer to reduce the computational time of the design space exploration. The method is applied to the multidisciplinary design of a High Speed Civil Transport (HSCT). A modified Lipschitzian optimization algorithm generates large sets of design points that are evaluated concurrently using a variety of load balancing schemes.The load balancing schemes implemented in this study are: static load balancing, dynamic load balancing with a master-slave organization, fully distributed dynamic load balancing, an fully distributed dynamic load balancing via threads. All of the parallel computing schemes have high parallel efficiencies. When the variation in the design evaluation times is small, the computational overhead needed for fully distributed dynamic load balancing is substantial enough so that it is more efficient to use a master-slave paradigm. However, when the variation in evaluation times is increased, fully distributed load balancing is the most efficient.
- Response Surface Models Combining Linear and Euler Aerodynamics for HSCT DesignKnill, Duane L.; Giunta, Anthony A.; Baker, Chuck A.; Grossman, Bernard M.; Mason, William H.; Haftka, Raphael T.; Watson, Layne T. (Department of Computer Science, Virginia Polytechnic Institute & State University, 1998-08-01)A method has been developed to efficiently implement supersonic aerodynamic predictions from Euler solutions into a highly constrained, multidisciplinary design optimization of a High-Speed Civil Transport. The method alleviates the large computational burden associated with performing computational fluid dynamics analyses through the use of variable-complexity modeling techniques, response surface methodologies, and coarse grained parallel computing. Using information gained from lower fidelity aerodynamic models, reduced term response surface models representing a correction to the linear theory response surface model predictions are constructed using Euler solutions. Studies into five, ten, fifteen, and twenty variable design problems show that accurate results can be obtained with the reduced term models at a fraction of the cost of creating the full term quadratic response surface models. Specifically, a savings of 255 CPU hours out of 392 CPU hours required to create the full term response surface model is obtained for the twenty variable problem on a single 75 MHz IP21 processor of a SGI Power Challenge.
- VizCraft: A Problem Solving Environment for Configuration Design of High Speed Civil TransportGoel, A.; Baker, Chuck A.; Shaffer, Clifford A.; Grossman, Bernard M.; Mason, William H.; Watson, Layne T.; Haftka, Raphael T. (Department of Computer Science, Virginia Polytechnic Institute & State University, 1999-09-01)We describe a problem solving environment (PSE) named VizCraft that aids aircraft designers during the conceptual design stage. At this stage,an aircraft design is defined by a vector of 10-30 parameters. The goal is to find a vector that minimizes a performance-based objective function while meeting a series of constraints. VizCraft integrates the simulation code that evaluates a design with visualization for analyzing a design individually or in contrast to other designs. VizCraft allows the designer to easily switch between the view of a design in the form of a parameter set, and a visualization of the corresponding aircraft geometry. The user can easily see which, if any, constraints are violated. VizCraft also allows the user to view a database of designs using parallel coordinates. Keywords: Problem solving environment,scientific data visualization, mutlidiimensional visualization, aircraft design, multidisciplinary design optimization.