首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   129篇
  免费   59篇
  国内免费   3篇
  2024年   1篇
  2023年   3篇
  2022年   1篇
  2021年   2篇
  2020年   10篇
  2019年   4篇
  2018年   2篇
  2017年   4篇
  2016年   11篇
  2015年   4篇
  2014年   6篇
  2013年   3篇
  2012年   8篇
  2011年   13篇
  2010年   5篇
  2009年   10篇
  2008年   8篇
  2007年   12篇
  2006年   15篇
  2005年   12篇
  2004年   10篇
  2003年   4篇
  2002年   7篇
  2001年   5篇
  2000年   4篇
  1999年   7篇
  1998年   8篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   3篇
  1992年   2篇
  1991年   1篇
  1989年   1篇
排序方式: 共有191条查询结果,搜索用时 578 毫秒
111.
简要介绍了GA和BP算法,利用遗传算法全局性搜索的特点,改变BP算法依赖梯度信息的指导来调整网络权值的方法,寻找最为合适的网络连接权和网络结构,提出了遗传算法优化BP神经网络的思路及其数学模型.最后,结合对某型航空装备的风险源的分析,利用此优化模型进行了验证.结果表明了该方法的可行性,为装备研制风险分析提供了一种新思路.  相似文献   
112.
针对风险管理中的装备供应链正向(供应)网络设计问题,在对装备供应链风险和成本进行量化分析的基础上,综合考虑风险和成本2方面因素,建立了基于风险控制的装备供应链网络设计优化模型。并设计了遗传算法对模型进行求解,给出在指定风险水平下最优设计方案与总成本。最后通过实例分析和计算,结果表明,该优化模型合理、有效、可行。  相似文献   
113.
We consider the problem of assigning a set of jobs to different parallel machines of the same processing speed, where each job is compatible to only a subset of those machines. The machines can be linearly ordered such that a higher‐indexed machine can process all those jobs that a lower‐indexed machine can process. The objective is to minimize the makespan of the schedule. This problem is motivated by industrial applications such as cargo handling by cranes with nonidentical weight capacities, computer processor scheduling with memory constraints, and grades of service provision by parallel servers. We develop an efficient algorithm for this problem with a worst‐case performance ratio of + ε, where ε is a positive constant which may be set arbitrarily close to zero. We also present a polynomial time approximation scheme for this problem, which answers an open question in the literature. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008  相似文献   
114.
在太赫兹频段,研究金属目标表面粗糙度对雷达散射截面(Radar Cross Section,RCS)的调制作用,对粗糙金属目标的RCS缩比测量具有重要意义.通过研究太赫兹粗糙金属目标镜面RCS随粗糙度的变化规律,结合相干、非相干散射理论,在基尔霍夫近似法的基础上,提出一种特定参数区间粗糙金属目标镜面RCS的预估方法,并...  相似文献   
115.
Machine learning algorithms that incorporate misclassification costs have recently received considerable attention. In this paper, we use the principles of evolution to develop and test an evolutionary/genetic algorithm (GA)‐based neural approach that incorporates asymmetric Type I and Type II error costs. Using simulated, real‐world medical and financial data sets, we compare the results of the proposed approach with other statistical, mathematical, and machine learning approaches, which include statistical linear discriminant analysis, back‐propagation artificial neural network, integrated cost preference‐based linear mathematical programming‐based minimize squared deviations, linear integrated cost preference‐based GA, decision trees (C 5.0, and CART), and inexpensive classification with expensive tests algorithm. Our results indicate that the proposed approach incorporating asymmetric error costs results in equal or lower holdout sample misclassification cost when compared with the other statistical, mathematical, and machine learning misclassification cost‐minimizing approaches. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.  相似文献   
116.
One traditional application of queueing models is to help set staffing requirements in service systems, but the way to do so is not entirely straightforward, largely because demand in service systems typically varies greatly by the time of day. This article discusses ways—old and new—to cope with that time‐varying demand. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007  相似文献   
117.
Job shop scheduling with a bank of machines in parallel is important from both theoretical and practical points of view. Herein we focus on the scheduling problem of minimizing the makespan in a flexible two-center job shop. The first center consists of one machine and the second has k parallel machines. An easy-to-perform approximate algorithm for minimizing the makespan with one-unit-time operations in the first center and k-unit-time operations in the second center is proposed. The algorithm has the absolute worst-case error bound of k − 1 , and thus for k = 1 it is optimal. Importantly, it runs in linear time and its error bound is independent of the number of jobs to be processed. Moreover, the algorithm can be modified to give an optimal schedule for k = 2 .  相似文献   
118.
In this article, we develop a stochastic approximation algorithm to find good bid price policies for the joint capacity allocation and overbooking problem over an airline network. Our approach is based on visualizing the total expected profit as a function of the bid prices and searching for a good set of bid prices by using the stochastic gradients of the total expected profit function. We show that the total expected profit function that we use is differentiable with respect to the bid prices and derive a simple expression that can be used to compute its stochastic gradients. We show that the iterates of our stochastic approximation algorithm converge to a stationary point of the total expected profit function with probability 1. Our computational experiments indicate that the bid prices computed by our approach perform significantly better than those computed by standard benchmark strategies and the performance of our approach is relatively insensitive to the frequency with which we recompute the bid prices over the planning horizon. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011  相似文献   
119.
The Annealing Adaptive Search (AAS) algorithm for global optimization searches the solution space by sampling from a sequence of Boltzmann distributions. For a class of optimization problems, it has been shown that the complexity of AAS increases at most linearly in the problem dimension. However, despite its desirable property, sampling from a Boltzmann distribution at each iteration of the algorithm remains a practical challenge. Prior work to address this issue has focused on embedding Markov chain‐based sampling techniques within the AAS framework. In this article, based on ideas from the recent Cross‐Entropy method and Model Reference Adaptive Search, we propose an algorithm, called Model‐based Annealing Random Search (MARS), that complements prior work by sampling solutions from a sequence of surrogate distributions that iteratively approximate the target Boltzmann distributions. We establish a novel connection between MARS and the well‐known Stochastic Approximation method. By exploiting this connection, we prove the global convergence of MARS and characterize its asymptotic convergence rate behavior. Our empirical results indicate promising performance of the algorithm in comparison with some of the existing methods. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011  相似文献   
120.
We study a knapsack problem with an additional minimum filling constraint, such that the total weight of selected items cannot be less than a given threshold. The problem has several applications in shipping, e‐commerce, and transportation service procurement. When the threshold equals the knapsack capacity, even finding a feasible solution to the problem is NP‐hard. Therefore, we consider the case when the ratio α of threshold to capacity is less than 1. For this case, we develop an approximation scheme that returns a feasible solution with a total profit not less than (1 ‐ ε) times the total profit of an optimal solution for any ε > 0, and with a running time polynomial in the number of items, 1/ε, and 1/(1‐α). © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2013  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号