分散搜索算法求解多目标优化问题

最近涌现了各种进化方法来解决多目标优化问题,分散搜索也是一种可以解决多目标问题的算法。该算法的结构引用进化算法的杂交和变异算子来增强它的性能,但该算法与其他进化算法的不同在于一系列操作策略不再基于随机性原理,而是运用“分散-收敛集聚”的迭代机制。论文在多目标优化问题区域讨论分散搜索算法,寻找多目标的非支配集或Pareto最优解。实验表明,分散搜索算法具有很好的收敛性和分布性。     

贝叶斯博弈多目标进化算法及其收敛性分析

多目标进化算法（MOEAs）主要依靠非支配解排序推动种群搜索Pareto前沿,在种群迭代搜索前期具有较好的全局寻优性能,但进化后期易出现收敛停滞现象,影响算法对于复杂优化问题的全局寻优能力。由此提出了一种基于静态贝叶斯博弈策略的多目标进化算法（SBG-MOEA）,将每个优化目标模拟为一个博弈参与者,以多次迭代中优化目标Pareto优化收敛程度映射为博弈收益,通过损益纳什均衡博弈机制驱动种群的Pareto寻优,理论分析证明了该方法具有全局收敛特性。基准测试函数的优化实验表明,与NSGA-II等经典算法相比,贝叶斯博弈策略有助于增强进化种群全局搜索能力。     

基于混合并行遗传算法的多目标约束优化技术研究

多目标约束优化问题属于NP问题。并行遗传算法是解决该类问题的常用算法,它具有较强的全局搜索能力和并行性,但局部搜索能力差,禁忌搜索算法则比较适合于局部搜索。提出了一种基于混合并行遗传算法的多目标约束优化方法,该方法综合了并行遗传算法和禁忌搜索算法的优势,改进了并行遗传算法的性能,能有效避免局部最优解。     

一种运动搜索算法的优化模型设计*

为了减少运动估计中全搜索过程的运算量,提出了一种运动搜索算法的优化模型。通过对运动搜索区域和搜索顺序的优化,缩小了全搜索范围并提高了匹配块搜索的速度。实验结果表明,在图像质量得到优化的前提下,较全搜索算法,该模型在不同频率的视频序列中搜索速度有了大幅的提高。     

一种改进的网格搜索闪电定位算法

闪电定位具有较高的实时性和定位精度要求,网格搜索算法存在计算量大的问题。提出了一种基于网格搜索的闪电定位算法优化方法。该方法采用多维空间数据索引快速搜索候选目标区域,通过对比存储在各候选目标区域上的SVM（Support Vector Machine）分类器的分类误差进行闪电定位。实验表明,该方法具有较好的定位精度和可靠性,且能满足实时闪电定位要求。     

面向不同目标覆盖要求的异构有向传感器网络节点调度算法

针对给定部署区域中不同的监测目标有不同的覆盖需求和现有的调度算法大多针对同构有向传感器节点忽略了节点异构对调度性能的影响的问题,提出两种异构有向传感器网络节点调度策略.一种方法是通过对问题进行数学建模,将节点调度问题转化为目标优化问题,采用改进的和声搜索算法进行求解.改进和声搜索算法针对原始和声搜索在陷入局部最优时的过...     

图象中目标的快速搜索算法

随着系统技术的发展,对目标识别跟踪系统的要求正朝着智能化方向发展,即要求系统具有对目标的自动捕获、自动识别和自动跟踪的能力。为此,在利用目标与背景之间的灰度分布特性的基础上,提出了一种在一定的范围内能自动搜索并锁定目标的目标搜索算法。该算法假定搜索过程是在一个较大的区域开始进行的,而目标仅是该区域内一个在灰度上与背景有差别的小区域。由于这个假定是符合实际情况的,因此该搜索算法可以看作是一个简单的主动边界方法,它首先由一个收缩算法逐步缩小搜索区域,再结合图象的梯度信息来搜索目标,最后锁定目标轮廓。该算法在搜索过程中只对少数的控制点进行计算,而且对控制点的初始位置无严格限制,因而可以在含有目标的区域快速完成搜索过程,实验结果表明,该算法对不同大小、不同形状的目标都可以取得很好的搜索结果。     

基于变精度粗糙集与量子贝叶斯网络的变压器故障诊断研究

及时准确的变压器故障诊断对电力部门正常运转而言意义重大。针对粗糙集与贝叶斯网络模型在变压器故障诊断中出现受噪声数据影响大、存在完全搜索NP困难等问题,提出基于变精度粗糙集与量子贝叶斯网络的变压器故障诊断模型。通过Grover量子搜索算法快速搜索变压器故障、征兆类型等目标数据,运用层次分析法删减对诊断故障影响较小的指标,并分析确定变精度粗糙集的错误分类率β,获得最小故障决策表,从而构建贝叶斯网络故障推理模型,实现对变压器故障的诊断研究。实例分析表明,与粗糙集、量子贝叶斯网络等模型相比,该模型更适合变压器故障的诊断且诊断精确。     

考虑随机旅行时间与二维装载约束的越库配送车辆路径优化

面向越库配送模式下二维装载和车辆路径联合优化,考虑现实配送过程的不确定性因素,提出考虑随机旅行时间和二维装载约束的越库配送车辆路径问题.基于蒙特卡洛模拟与场景分析方法,建立以运输成本、车辆固定成本以及时间窗期望惩罚成本之和最小化为目标的带修正随机规划模型.继而根据问题特征,设计改进的自适应禁忌搜索算法和基于禁忌搜索的多重排序最佳适应装箱算法进行求解.其中,改进的自适应禁忌搜索算法在禁忌搜索算法的基础上引入自适应机制,对不同邻域算子进行动态选择,并提出基于移除-修复策略的多样性机制以增强算法的寻优能力.数值实验表明,所提出的模型与方法能够有效求解考虑随机旅行时间和二维装载约束的越库配送车辆路径问题,自适应与多样性机制能一定程度上增强算法的全局搜索能力.     

针对动态目标的多无人机协同组合差分进化搜索方法

针对多无人机动态目标协同搜索问题,提出一种组合差分进化无人机协同搜索航迹规划方法.建立动态目标协同搜索环境信息图模型及无人机运动模型.基于改进差分蝙蝠算法和自适应差分进化算法,设计基于种群数量自适应分配的组合框架,将差分进化算法中的变异、交叉和选择机制引入蝙蝠算法,构建组合差分进化算法的协同搜索算法,并对无人机动态目标协同搜索的航迹进行优化.针对待搜索目标轨迹随机多变且具有规避侦察特性的现实场景,建立可回访数字信息图和自适应目标搜索增益函数,从而提高无人机对动态目标的捕获能力.最后,通过仿真结果验证所提出的无人机动态目标协同搜索算法的有效性.     

基于认知差异的多机器人协同信息趋向烟羽源搜索方法

多机器人协同稀疏烟羽源搜索研究中,追求群体信息一致而忽视个体独立搜索能力的发挥,导致群体无法有效适应复杂搜索状况.为此,提出一种基于认知差异的协同信息趋向源搜索方法.首先,利用相对熵度量群内个体对源位置估计的认知差异;然后,据此赋予不同个体烟羽采样以相应权重,在贝叶斯推理过程自适应权衡自身线索与群体线索;最后,采用分布式信息熵决策实施协同信息趋向搜索.多种场景下的仿真结果验证了所提出算法的优越性.     

Coordinated search for a lost target in a Bayesian world

This paper describes a decentralized Bayesian approach to the problem of coordinating multiple autonomous sensor platforms searching for a single non-evading target. In this architecture, each decision maker builds an equivalent representation of the probability density function (PDF) of the target state through a general decentralized Bayesian sensor network, enabling them to coordinate their actions without exchanging any information about their plans. The advantage of the approach is that a high degree of scalability and real-time adaptability can be achieved. The framework is implemented on a real-time high-fidelity multi-vehicle simulator system. The effectiveness of the method is demonstrated in different scenarios for a team of airborne search vehicles looking for both a stationary and a drifting target lost at sea.     

Image retrieval using multiple evidence ranking

The World Wide Web is the largest publicly available image repository and a natural source of attention. An immediate consequence is that searching for images on the Web has become a current and important task. To search for images of interest, the most direct approach is keyword-based searching. However, since images on the Web are poorly labeled, direct application of standard keyword-based image searching techniques frequently yields poor results. We propose a comprehensive solution to this problem. In our approach, multiple sources of evidence related to the images are considered. To allow combining these distinct sources of evidence, we introduce an image retrieval model based on Bayesian belief networks. To evaluate our approach, we perform experiments on a reference collection composed of 54000 Web images. Our results indicate that retrieval using an image surrounding text passages is as effective as standard retrieval based on HTML tags. This is an interesting result because current image search engines in the Web usually do not take text passages into consideration. Most important, according to our results, the combination of information derived from text passages with information derived from HTML tags leads to improved retrieval, with relative gains in average precision figures of roughly 50 percent, when compared to the results obtained by the use of each source of evidence in isolation.     

多目标优化问题的蚁群算法研究

将离散空间问题求解的蚁群算法引入连续空间,针对多目标优化问题的特点,提出一种用于求解带有约束条件的多目标函数优化问题的蚁群算法.该方法定义了连续空间中信息量的留存方式和蚂蚁的行走策略,并将信息素交流和基于全局最优经验指导两种寻优方式相结合,用以加速算法收敛和维持群体的多样性.通过3组基准函数来测试算法性能,并与NSGAII算法进行了仿真比较.实验表明该方法搜索效率高,向真实Pareto前沿逼近的效果好,获得的解的散布范围广,是一种求解多目标优化问题的有效方法.     

进化贝叶斯优化的核极限学习机分类器

为解决传统核极限学习机算法参数优化困难的问题,提高分类准确度,提出一种改进贝叶斯优化的核极限学习机算法.用樽海鞘群设计贝叶斯优化框架中获取函数的下置信界策略,提高算法的局部搜索能力和寻优能力;用这种改进的贝叶斯优化算法对核极限学习机的参数进行寻优,用最优参数构造核极限学习机分类器.在UCI真实数据集上进行仿真实验,实验...     

GENMARK: Parallel gene recognition for both DNA strands

The problem of predicting gene locations in newly sequenced DNA is well known but still far from being successfully resolved. A novel approach to the problem based on the frame dependent (non-homogeneous) Markov chain models of protein-coding regions was previously suggested. This approach is, apparently, one of the most powerful “search by content” methods. The initial idea of the method combines the specific Markov models of coding and non-coding region together with Bayes' decision making function and allows easy generalization for employing of higher order Markov chain models. Another generalization which is described in this article allows the analysis of both DNA strands simultaneously. Currently known gene searching methods perform the analysis of the two DNA strands in turn, one after another. In doing this all the known methods fail in the sense that they generate false (artifactual) prediction signals for the given strand when the real coding region is located on the complementary DNA strand. This common drawback is avoided by employing the Bayesian algorithm which uses an additional non-homogeneous Markov chain model of the “shadow” of the coding region—the sequence which is complementary to the protein-coding sequence.     

Structure learning of Bayesian networks by genetic algorithms: aperformance analysis of control parameters

We present a new approach to structure learning in the field of Bayesian networks. We tackle the problem of the search for the best Bayesian network structure, given a database of cases, using the genetic algorithm philosophy for searching among alternative structures. We start by assuming an ordering between the nodes of the network structures. This assumption is necessary to guarantee that the networks that are created by the genetic algorithms are legal Bayesian network structures. Next, we release the ordering assumption by using a “repair operator” which converts illegal structures into legal ones. We present empirical results and analyze them statistically. The best results are obtained with an elitist genetic algorithm that contains a local optimizer     

Multi-center variable-scale search algorithm for combinatorial optimization problems with the multimodal property

Combinatorial optimization problems (COPs) are discrete problems arising from aerospace, bioinformatics, manufacturing, and other fields. One of the classic COPs is the scheduling problem. Moreover, these problems are usually multimodal optimization problems with a quantity of global and local optima. As a result, many search algorithms can easily become trapped into local optima. In this article, we propose a multi-center variable-scale search algorithm for solving both single-objective and multi-objective COPs. The algorithm consists of two distinct points. First, the multi-center strategy chooses several individuals with better performance as the only parents of the next generation, which means that there are a number of separate searching areas around the searching center. Second, the next generation of the population is produced by a variable-scale strategy with an exponential equation based on the searching center. The equation is designed to control the neighborhood scale, and adaptively realize the large-scale and small-scale searches at different search stages to balance the maintenance of diversity and convergence speed. In addition, an approach of adjusting centers is proposed concerning the number and distribution of centers for solving multi-objective COPs. Finally, the proposed algorithm is applied to three COPs, including the well-known flexible job shop scheduling problem, the unrelated parallel machine scheduling problem, and the test task scheduling problem. Both the single-objective optimization algorithm and the multi-objective optimization algorithm demonstrate competitive performance compared with existing methods.     

Evaluating a workspace’s usefulness for image retrieval

Image searching is a creative process. We have proposed a novel image retrieval system that supports creative search sessions by allowing the user to organise their search results on a workspace. The workspace’s usefulness is evaluated in a task-oriented and user-centred comparative experiment, involving design professionals and several types of realistic search tasks. In particular, we focus on its effect on task conceptualisation and query formulation. A traditional relevance feedback system serves as a baseline. The results of this study show that the workspace is more useful in terms of both of the above aspects and that the proposed approach leads to a more effective and enjoyable search experience. This paper also highlights the influence of tasks on the users’ search and organisation strategy.     

采用捕鱼策略的优化方法

引入一种采用渔夫捕鱼策略的新的优化方法。该优化方法主要采用移动搜索、收缩搜索和加速搜索三种搜索技术。设初始时在搜索域中随机分布有若干个点,每个点看作一个“渔夫”,每个“渔夫”通过移动、收缩和加速三种搜索方式在搜索空间中独立开展寻优活动,以搜寻全局的最优解或最优点。测试结果表明,该算法具有较好的全局搜索能力,因而该优化方法是有效的和可行的。