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1.
为了解决多人旅行商问题,文章提出了一种基于二叉树编码的改进遗传算法。将多旅行商问题转化为等效的AOV图,并将其转化成二叉树,然后进行遍历编码,再用改进的遗传算子进行算法优化。该算法克服了一维编码的局限性,通过仿真实验验证了其有效性及比普通的一位编码遗传算法更高的执行效率。 相似文献
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《科技风》2017,(16)
旅行商问题是一个组合优化问题,具有重要的实际意义。而遗传算法是求解旅行商问题的典型算法之一。本文首先介绍了旅行商问题的定义以及它的研究背景、发展现状和常用算法。在此基础上,详细阐述了遗传算法原理。通过改进这些算子,改进了传统的遗传算法,提高了算法的效率,降低了它的时间及空间复杂度。本文使用路径总长度的倒数作为适应度函数,保证了解向着最优化方向发展。然后选择部分交叉算子来产生新个体,保证了迭代的效率。变异算子利用位点变异,使算法变得简单,易行。最后,使用MATLAB语言进行编程,解决了城市数目分别为15和25时的两个实际问题。通过对这两个问题的收敛速度的对比、分析,总结了遗传算法求解旅行商问题的特点。 相似文献
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文章研究多无人机协同侦察相控阵雷达模式转移规律过程中的任务分配优化.为了以最小能耗无重复侦察雷达全部波位,根据相控阵雷达波位覆盖方式,分析比较了三种波位侦察点选择方案.在此基础上,根据侦察点访问约束、无人机航程和能耗约束,以无人机总能耗最低为目标,建立多无人机侦察任务分配的多旅行商优化模型.基于单亲遗传—粒子群混合算法(PGA-PSO),使用分组最优个体选择和多变异操作,保证算法快速收敛的同时,提高算法求解精度.仿真结果表明,通过优选侦察点和优化任务分配可大幅提高多无人机协同的侦察效率,改进的PGA-PSO算法较其他算法求解精度高,收敛速度快. 相似文献
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当前的制造公司,其制造业活动通常表现为多样性和小批量,而加工车间缺乏有效节能的调度方案和管理,已经严重的制约了公司实现可持续性制造。为了解决这个问题,本文提出了对应机器加工过程不同阶段的能耗模型并借助模拟退火优化算法,针对用不同的机器同时生产多个零件的进程调度问题进行了优化以提高加工车间对动态任务的适应和响应能力,从而实现在整个车间获得更高的能源效率和更短的加工时间。验证提供的工业案例结果证实了该方法在实现高效节能的车间规划和调度的适用性和有效性。 相似文献
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分析了遗传算法和模拟算法的主要优缺点,提出一种用于求解旅行商问题（TSP）的改进遗传算法,该算法有效地将遗传算法和模拟退火算法相结合,在很大程度上缩短了算法的搜索时间;利用MATLAB对多种TSP问题进行仿真研究,实验结果证明了改进的遗传算法的有效性。 相似文献
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混合遗传蚁群算法的改进及在TSP问题中的应用研究 总被引：1，自引：0，他引：1
蚁群算法(ACA)与遗传算法(GA)都属于仿生型优化算法,是解决组合优化问题的强有力工具,并都分别成功应用于旅行商问题(TSP)中.本文将两种算法进行融合,并给出了新的融合方式.实验结果表明,新的遗传蚁群混合算法有效地改进了算法的全局收敛性,并加快了收敛速度. 相似文献
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传统车辆调度模型针对复杂的路况和复杂的车辆流动信息,存在调度时间长、难以提供实时调度时间的缺点,从而造成模型中前后级调度信号失联、调度算法冲突,效率不高的问题.本文提出一种改进遗传算法交通调度平台大规模拥堵优化调度方案.通过对算法编码过程进行合理的优化,加入针对多调度中心的约束条件防止算法陷入早熟,通过不同的分析角度,分别建立的回路形式和时间优化控制形式对车辆进行合理的调度.仿真结果显示,改进后的算法有效地降低了车辆平均延误时间,提高了交通运行效率. 相似文献
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在计算机多分簇任务执行中,由于初始能量有限,需要对网络分簇能耗进行优化分配,提高任务执行效率。提出基于剩余能量相干均衡的网络分簇能耗双阈值分配算法,算法考虑了节点当前能量、簇成员数量、簇首与节点间距离,设计了能耗指导的分布式网络能量采集和消耗均衡模型,采用收敛性度量值进行路由分配,实现能耗的双阈值分配,在系统的全局任务调度中心将所有任务进行融合,输入系统总调度器,设计剩余能量相干均衡算法,构建能耗分配的双阈值模型,实现网络分簇能耗双阈值分配。实验结果表明,算法能够降低任务调度关键路径延时,提高low-Vt单元使用率,降低相干功耗,形成最优化能耗管理输出,使得系统更加稳定。 相似文献
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针对特定的多源旅行商问题,给出了将其转化为单源旅行商问题的一种方法,并用改进的遗传算法加以解决,无论在理论研究还是实际应用中,都有一定的创新. 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
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A research group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol-a chemical found in the skins of red grapes in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said. 相似文献
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Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
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Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献
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Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
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Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
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Active biological molecules functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery disease diagnosis therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction. 相似文献
20.
《中国科学院院刊(英文版)》2014,(3)
<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence 相似文献