共查询到20条相似文献,搜索用时 93 毫秒
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改进HS共轭梯度算法及其全局收敛性 总被引:14,自引:0,他引:14
1.引 言 1952年 M.Hestenes和E.Stiefel提出了求解正定线性方程组的共轭梯度法[1].1964年R.Fletcher和C.Reeves将该方法推广到求解下列无约束优化问题: minf(x),x∈Rn,(1)其中f:Rn→R1为连续可微函数,记gk= f(xk),xk∈ Rn. 若点列{xk}由如下算法产生:其中 βk=[gTk(gk-gk-1)]/[dTk-1(gk-gk-1)].(Hestenes-Stiefel) (4)则称该算法为 Hestenes—Stiefel共轭梯度算… 相似文献
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武同锁 《数学年刊A辑(中文版)》1995,(6)
本文讨论U1-sr条件,这一条件有益于计算环的K1群.得到主要结果为;(1)完全确定满足U1-sr条件的半局部环:(2)给出使EndR(M)满足U1-sr条件的一个刻划;(3)引进比U1-sr更强的一个条件SU1-sr,利用上述结果证明了:若R∈SU1-sr,则Mn(R)∈U1-sr;(4)证明了对于满足SU1-sr的环R,K1R=GL1(R)ab. 相似文献
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S~1×S~1-Borsuk-UlamTheoremonProductSpacesZhongChengkui(钟承奎)(DepartmentofMathematics,LanzhouUniversity,Lanzhou,730000)Abstract:... 相似文献
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IntegralSolutionOperatorsfortheCauchy-RiemannEquationsonanOpenSetwithPiecewiseC ̄1-BoundaryMaZhongtai(马忠泰)(Dept.ofMath.Shandon... 相似文献
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§1. IntroductionLetΩbearegularconeinRn,Φ:Cm×Cm→Cn=Rn+iRnanΩ-positiveHermitianmap.TheSiegeldomainDΩ,ΦoftypetwoinCn×CmisdefinedbyDΩ,Φ={(z,w)∈:Cn×Cm:Imz-Φ(w,w)∈Ω}(1)(see[6]).Specially,weassumethatn=m,Ω={t=(t1,t2,…,tn)∈Rn:ti>0,i=1,2,…,n},Φ(u,v)=u·v=(u1u… 相似文献
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GLOBAL ATTRACTOR OF A SPATIALLY DISCRETIZED REACTION-DIFFUSION SYSTEM WITH HAMILTONIAN STRUCTURE 总被引:1,自引:0,他引:1
1HamiltonianStructureinReaction-DifusionsystemConsiderasystemofreaction-difusionequationsut=uxx+f(u,v)vt=vxx+g(u,v){(1.1)wher... 相似文献
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本文主要讨论高维空间非线性波动方程的Cauchy问题整体解的非存在性,我们证明对Uu-△u=f(u),f(u)=c|u|p-1u,当1<p≥时,若初始能量非正,则无论初值数据的ck-范数(连续空间范数)多么小,解按Ck-范数或按Hs(Rn)(S≥1)都在有限时间内Blowup,并且有相同的生命跨度. 相似文献
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Zero-freeRegionsforDirichletL-functionsandtheExceptionalSetofGoldbachNumbersLiHongze(李红泽)MR(1991)SubjectClasification:11N13,1... 相似文献
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A two-stage intelligent search algorithm for the two-dimensional strip packing problem 总被引:2,自引:0,他引:2
Stephen C.H. LeungDefu Zhang Kwang Mong Sim 《European Journal of Operational Research》2011,215(1):57-69
This paper presents a two-stage intelligent search algorithm for a two-dimensional strip packing problem without guillotine constraint. In the first stage, a heuristic algorithm is proposed, which is based on a simple scoring rule that selects one rectangle from all rectangles to be packed, for a given space. In the second stage, a local search and a simulated annealing algorithm are combined to improve solutions of the problem. In particular, a multi-start strategy is designed to enhance the search capability of the simulated annealing algorithm. Extensive computational experiments on a wide range of benchmark problems from zero-waste to non-zero-waste instances are implemented. Computational results obtained in less than 60 seconds of computation time show that the proposed algorithm outperforms the supposedly excellent algorithms reported recently, on average. It performs particularly better for large instances. 相似文献
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当前国内B2C电子商务仓库多为人至物的拣货模式,拣货作业成为其核心作业之一,占据仓库大量时间成本和资金成本,拣货路径优化成为企业亟需解决的问题。本文基于TSP对拣货路径进行建模,利用蚁群算法、模拟退火算法和禁忌搜索对该NP-hard问题进行求解,并同当前企业普遍采用的S型启发式策略进行对比,拣货时间节约13.35%。进一步得出当拣货品数量较少时应采用模拟退火算法求解,而当拣货品数量较大时采用蚁群算法仅进行一次迭代,则可以实现短时间得到相对较优的解。所得结果已应用于某大型电子商务企业,效果明显。 相似文献
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混合模拟退火-进化策略在非线性参数估计中的应用 总被引:2,自引:0,他引:2
提出了一种混合模拟退火-进化策略算法应用在非线性参数估计中,方法克服了传统优化方法估计参数精度不高且容易陷入局部极小值等缺点,并且将模拟退火算法和进化策略算法相结合,充分发挥各自算法优点.最后通过给出非线性参数估计算例,结果表明,算法具有参数估计精度较高,收敛速度快,自适应性强,在实际工程中有较大的应用价值. 相似文献
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Membrane algorithms (MAs), which inherit from P systems, constitute a new parallel and distribute framework for approximate computation. In the paper, a membrane algorithm is proposed with the improvement that the involved parameters can be adaptively chosen. In the algorithm, some membranes can evolve dynamically during the computing process to specify the values of the requested parameters. The new algorithm is tested on a well-known combinatorial optimization problem, the travelling salesman problem. The em-pirical evidence suggests that the proposed approach is efficient and reliable when dealing with 11 benchmark instances, particularly obtaining the best of the known solutions in eight instances. Compared with the genetic algorithm, simulated annealing algorithm, neural net-work and a fine-tuned non-adaptive membrane algorithm, our algorithm performs better than them. In practice, to design the airline network that minimize the total routing cost on the CAB data with twenty-five US cities, we can quickly obtain high quality solutions using our algorithm. 相似文献
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Membrane algorithms (MAs), which inherit from P systems, constitute a new parallel and distribute framework for approximate computation. In the paper, a membrane algorithm is proposed with the improvement that the involved parameters can be adaptively chosen. In the algorithm, some membranes can evolve dynamically during the computing process to specify the values of the requested parameters. The new algorithm is tested on a well-known combinatorial optimization problem, the travelling salesman problem. The empirical evidence suggests that the proposed approach is efficient and reliable when dealing with 11 benchmark instances, particularly obtaining the best of the known solutions in eight instances. Compared with the genetic algorithm, simulated annealing algorithm, neural network and a fine-tuned non-adaptive membrane algorithm, our algorithm performs better than them. In practice, to design the airline network that minimize the total routing cost on the CAB data with twenty-five US cities, we can quickly obtain high quality solutions using our algorithm. 相似文献
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本文在经典的带时间窗的车辆路径问题(VRPTW)的基础上,考虑不同时间段车辆行驶速度不同的情况,研究速度时变的带时间窗车辆路径问题(TDVRPTW),使问题更具实际意义。本文用分段函数表示不同时间段下的车辆行驶速度,并解决了速度时变条件下行驶时间计算的问题。针对模拟退火算法(SA)在求解VRPTW问题时易陷入局部最优解,变邻域搜索算法(VNS)在求解VRPTW问题时收敛速度慢的问题,本文将模拟退火算法以一定概率接受非最优解的思想和变邻域搜索算法系统地改变当前解的邻域结构以拓展搜索范围的思想结合起来,提出了一种改进的算法——变邻域模拟退火算法(SAVN),使算法在退火过程中一陷入局部最优解就改变邻域结构,更换搜索范围,以此提升算法跳出局部最优解的能力,加快收敛速度。通过在仿真实验中将SAVN算法的求解结果与VNS算法、SA算法进行对比,验证了SAVN算法确实能显著提升算法跳出局部最优解的能力。 相似文献