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911.
Solving the flight perturbation problem with meta heuristics 总被引:1,自引:0,他引:1
Tobias Andersson 《Journal of Heuristics》2006,12(1-2):37-53
When there is a perturbation in a carefully constructed aircraft schedule, e.g. an aircraft breakdown, it is important to
minimize the negative consequences of this disturbance. Here, a tabu search and a simulated annealing approach to the flight
perturbation problem are presented. The heuristics use a tree-search algorithm to find new schedules for the aircraft, and
utilize a path relinking strategy to explore paths between structurally different solutions. The computational results indicate
that the solution strategies, especially the tabu search, can be successfully used to solve the flight perturbation problem. 相似文献
912.
This paper presents a discussion on 2D block mappings for the sparse Cholesky factorization on parallel MIMD architectures
with distributed memory. It introduces the fan-in algorithm in a general manner and proposes several mapping strategies. The
grid mapping with row balancing, inspired by Rothberg's work (1994), is proved to be more robust than the original fan-out
algorithm. Even more efficient is the proportional mapping, as shown by the experiments on a 32 processor IBM SP1 and on a
Cray T3D. Subforest-to-subcube mappings are also considered and give good results on the T3D.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
913.
David Goudin Pascal Hénon François Pellegrini Pierre Ramet Jean Roman Jean-Jacques Pesqué 《Numerical Algorithms》2000,24(4):371-391
The framework of this paper is the parallelization of a plasticity algorithm that uses an implicit method and an incremental
approach. More precisely, we will focus on some specific parallel sparse linear algebra algorithms which are the most time-consuming
steps to solve efficiently such an engineering application. First, we present a general algorithm which computes an efficient
static scheduling of block computations for parallel sparse linear factorization. The associated solver, based on a supernodal
fan-in approach, is fully driven by this scheduling. Second, we describe a scalable parallel assembly algorithm based on a
distribution of elements induced by the previous distribution for the blocks of the sparse matrix. We give an overview of
these algorithms and present performance results on an IBM SP2 for a collection of grid and irregular problems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
914.
Due to the interfacial tension, immiscible blends can show an elastic recovery that is substantially larger than that of
their pure components. Here it is attempted to relate the elastic recovery after steady shear flow to the underlying morphology.
On the one hand, the predictions of the Palierne and the Doi-Ohta models are calculated for the flow conditions during recoil.
On the other hand, systematic recoil experiments after steady state shearing have been performed on a model blend. As the
component polymers hardly show any recoil under the stresses applied in these tests, the measured recovery can be attributed
completely to the action of the interface. Comparison of the model predictions with the experimental results shows that the
recoverable strain can be derived quantitatively from the linear Palierne theory. Although the droplet deformation remained
limited during the preshear, the retardation time predicted by this model has to be multiplied by the aspect ratio of the
droplet phase to the power 2/3 to describe the experiments. For conditions in which the material does not show an intrinsic
length scale, particular scaling relations as derived from the Doi-Ohta theory are found to apply also to recoil.
Received: 5 August 1998 Accepted: 17 November 1998 相似文献
915.
Jan Mayer 《Numerical Linear Algebra with Applications》2005,12(9):941-955
We introduce a new preconditioner, ILUCP, to be used with an iterative method for solving sparse linear systems. It is based on an incomplete LU factorization combining Crout's formulation of Gaussian elimination with pivoting by columns. It is usually faster than ILUTP, which is based on a delayed update version of Gaussian elimination with pivoting, but requires more memory. For applications where memory is not a primary concern, ILUCP can be an attractive alternative to ILUTP. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
916.
Jan Mayer 《Numerical Linear Algebra with Applications》2007,14(10):771-789
In this paper, we present a new incomplete LU factorization using pivoting by columns and row permutation. Pivoting by columns helps to avoid small pivots and row permutation is used to promote sparsity. This factorization is used in a multilevel framework as a preconditioner for iterative methods for solving sparse linear systems. In most multilevel incomplete ILU factorization preconditioners, preprocessing (scaling and permutation of rows and columns of the coefficient matrix) results in further improvements. Numerical results illustrate that these preconditioners are suitable for a wide variety of applications. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
917.
ALMOSTPERIODICSOLUTIONSOFLINEARDIFFERENTIALEQUATIONSWITHPIECEWISECONSTANTARGUMENTYUANRONGHONGJIALINManuscriptreceivedJu... 相似文献
918.
Alberto Cabada Juan B Ferreiro 《Journal of Mathematical Analysis and Applications》2004,291(2):690-697
In this paper we obtain the expression of the Green's function related with a first order periodic differential equation with piecewise constant argument. We derive comparison results for the treated linear operator by studying the sign of the obtained Green's function. 相似文献
919.
920.
10 GHz clock recovery from 40 Gbps optical time-division-multiplexed (OTDM) signal pulses is experimentally demonstrated using optical phase lock loop based on a terahertz optical asymmetric demultiplexer (TOAD) with a local-reference-oscillator-free electronic feedback circuit. The clock pulse that was used as the control pulse had energy of 800 fJ and the SNR of the time-extracted 10 GHz RF signal to the side components was larger than 40 dB. 相似文献