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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 53 (1992), S. 323-338 
    ISSN: 1436-4646
    Keywords: Random search ; Monte Carlo optimization ; global optimization ; complexity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Pure adaptive seach iteratively constructs a sequence of interior points uniformly distributed within the corresponding sequence of nested improving regions of the feasible space. That is, at any iteration, the next point in the sequence is uniformly distributed over the region of feasible space containing all points that are strictly superior in value to the previous points in the sequence. The complexity of this algorithm is measured by the expected number of iterations required to achieve a given accuracy of solution. We show that for global mathematical programs satisfying the Lipschitz condition, its complexity increases at mostlinearly in the dimension of the problem.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 43 (1989), S. 317-328 
    ISSN: 1436-4646
    Keywords: Random search ; Monte Carlo optimization ; convex programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Pure adaptive search constructs a sequence of points uniformly distributed within a corresponding sequence of nested regions of the feasible space. At any stage, the next point in the sequence is chosen uniformly distributed over the region of feasible space containing all points that are equal or superior in value to the previous points in the sequence. We show that for convex programs the number of iterations required to achieve a given accuracy of solution increases at most linearly in the dimension of the problem. This compares to exponential growth in iterations required for pure random search.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of global optimization 3 (1993), S. 171-192 
    ISSN: 1573-2916
    Keywords: Random search ; Monte Carlo optimization ; algorithm complexity ; global optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Improving Hit-and-Run is a random search algorithm for global optimization that at each iteration generates a candidate point for improvement that is uniformly distributed along a randomly chosen direction within the feasible region. The candidate point is accepted as the next iterate if it offers an improvement over the current iterate. We show that for positive definite quadratic programs, the expected number of function evaluations needed to arbitrarily well approximate the optimal solution is at most O(n5/2) wheren is the dimension of the problem. Improving Hit-and-Run when applied to global optimization problems can therefore be expected to converge polynomially fast as it approaches the global optimum.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2011-08-24
    Description: The control-point form (CPF) formulation is an algebraically defined class of coordinate transformations by means of which the interior form of the coordinates can be manipulated in the local fashion, and any boundary can be either specified or manipulated in a similar manner. Currently, the most intense activity involving CPF is with such graphic interactive codes as TurboI and TurboT, for which detailed illustrative examples are given; these have furnished experience on whose basis future interactive strategies can be developed.
    Keywords: NUMERICAL ANALYSIS
    Type: In: Finite elements in fluids. Vol. 8 (A93-45962 19-34); p. 97-116.
    Format: text
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  • 5
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    In:  Other Sources
    Publication Date: 2011-08-19
    Description: Algebraic grid generation is the direct expression of a physical coordinate system as a function of a uniform grid in a rectangular computational coordinate system. Algebraic grid generation is based on mathematical interpolation and is presented in general terms of multivariate transfinite interpolation. The multisurface method and the two-boundary technique are described as univariate procedures that can be applied within the context of transfinite interpolation. A technique for grid clustering is described. Problems that are commonly encountered in three-dimensional grid generation are discussed and approaches for dealing with complex physical domains using multiple computational grid blocks are presented.
    Keywords: NUMERICAL ANALYSIS
    Type: Computer Methods in Applied Mechanics and Engineering (ISSN 0045-7825); 64; 285-300
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  • 6
    Publication Date: 2013-08-31
    Description: The facilities and services of the GEOmetry LABoratory (GEOLAB) at the NASA Langley Research Center are described. Included in this description are the laboratory functions, the surface modeling and grid generation technologies used in the laboratory, and examples of the tasks performed in the laboratory.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA. Lewis Research Center, Surface Modeling, Grid Generation, and Related Issues in Computational Fluid Dynamic (CFD) Solutions; p 69-86
    Format: application/pdf
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  • 7
    Publication Date: 2017-10-02
    Description: Experiences at the NASA Langley Research Center generating grids about a cranked wing fighter aircraft configuration is described. A single block planar grid about the fuselage and canard used with a finite difference Navier-Stokes solver is also described. A dual block nonplanar grid about the complete configuration and used with a finite volume Euler solver is presented. The very important aspect of computing the aircraft surface grid, starting with a standardized model description, is also presented.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: AGARD, Three Dimensional Grid Generation for Complex Configuration: Recent Progress; p 56-64
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  • 8
    Publication Date: 2018-12-01
    Description: This paper describes an interactive procedure to construct grids about fighter aircraft using a state-of-the-art workstation. The aircraft are characterized by a fuselage with an integrated canopy over the cockpit, an engine inlet, an area ruled midsection, canards, and highly-swept cranked delta wings or strakes integrated into the wings and tail surfaces. The grid topology, configuration surface grid, exterior grid computation, and computational interactive process are addressed.
    Keywords: NUMERICAL ANALYSIS
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  • 9
    Publication Date: 2019-06-28
    Description: The geometric requirements for creating surfaces and grids for multidisciplinary analysis and optimization of aerospace-vehicle designs are described. Geometric surface representations are outlined and compared. Directions for future designs are proposed. High-speed civil transport aircraft configurations are targeted to demonstrate the processes.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: AIAA PAPER 92-4773 , In: AIAA(USAF)NASA/OAI Symposium on Multidisciplinary Analysis and Optimization, 4th, Cleveland, OH, Sept. 21-23, 1992, Technical Papers. Pt. 2 (A93-20301 06-66); p. 686-694.
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  • 10
    Publication Date: 2019-06-28
    Description: Deciding on an appropriate population size for a given Genetic Algorithm (GA) application can often be critical to the algorithm's success. Too small, and the GA can fall victim to sampling error, affecting the efficacy of its search. Too large, and the GA wastes computational resources. Although advice exists for sizing GA populations, much of this advice involves theoretical aspects that are not accessible to the novice user. An algorithm for adaptively resizing GA populations is suggested. This algorithm is based on recent theoretical developments that relate population size to schema fitness variance. The suggested algorithm is developed theoretically, and simulated with expected value equations. The algorithm is then tested on a problem where population sizing can mislead the GA. The work presented suggests that the population sizing algorithm may be a viable way to eliminate the population sizing decision from the application of GA's.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-CR-194277 , NAS 1.26:194277
    Format: application/pdf
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