基于蚁群算法的港口集装箱运输网络径流优化

针对区域性港口集装箱海上运输网络系统的最小费用流问题,引入新兴的智能仿生蚁群优化算法,用蚁群在搜索食物源的过程中所体现出来的寻优能力来解决集装箱海上运输网络系统的非线性NP-C问题;构建蚁群优化模型对某外贸经济区域内的集装箱运输网络系统进行优化计算,结果表明,所提出的优化模型可以使网络费用流在较短时间内收敛到最优状态,为下一步合理进行集装箱运输网络的航线配置提供了一个参考依据.     

Trail geometry gives polarity to ant foraging networks

Pheromone trails are used by many ants to guide foragers between nest and food. But how does a forager that has become displaced from a trail know which way to go on rejoining the trail? A laden forager, for example, should walk towards the nest. Polarized trails would enable ants to choose the appropriate direction, thereby saving time and reducing predation risk. However, previous research has found no evidence that ants can detect polarity from the pheromone trail alone. Pharaoh's ants (Monomorium pharaonis) produce elaborate trail networks throughout their foraging environment. Here we show that by using information from the geometry of trail bifurcations within this network, foragers joining a trail can adaptively reorientate themselves if they initially walk in the wrong direction. The frequency of correct reorientations is maximized when the trail bifurcation angle is approximately 60 degrees, as found in natural networks. These are the first data to demonstrate how ant trails can themselves provide polarity information. They also demonstrate previously unsuspected sophistication in the organization and information content of networks in insect societies.     

Insect communication: 'no entry' signal in ant foraging

Forager ants lay attractive trail pheromones to guide nestmates to food, but the effectiveness of foraging networks might be improved if pheromones could also be used to repel foragers from unrewarding routes. Here we present empirical evidence for such a negative trail pheromone, deployed by Pharaoh's ants (Monomorium pharaonis) as a 'no entry' signal to mark an unrewarding foraging path. This finding constitutes another example of the sophisticated control mechanisms used in self-organized ant colonies.     

一种基于监工机制的改进蚁群算法

针对基本蚁群算法存在收敛速度慢、易陷入局部最优解等问题,受监工机制的启发,提出了监工蚁群算法,以监工距离作为评价标准,自适应地选择优良的蚂蚁更新信息素,提高了每次迭代中解的质量,指导之后的蚂蚁进行更好的学习。该算法选用优化的全局更新策略,使得信息素在进化前期增加较多,在后期增加较少;同时,自适应地将信息素的值限定在一定范围内,防止某条路径被选择的概率过大或者过小。该算法还添加了发散和收敛机制,当算法陷入局部最优解时,增加探索的概率,有助于跳出局部最优解。仿真结果表明,监工蚁群算法具有较高的全局寻优能力,减少了迭代次数,增强了算法的稳定性。     

大型船体装焊车间焊接烟尘扩散模式理论探讨

目前国内外对焊接烟尘主要集中在发生机理、性质和治理等方面的研究，但对其在室内的扩散方式、运动轨迹等方面几乎没有具体的探讨。这里利用成熟的室外大气污染物扩散理论—梯度输送理论和箱模式理论，提出焊接烟尘在室内的扩散模式和浓度分布的理论计算方法。     

A Dynamic Job Shop Scheduling Method Based on Ant Colony Coordination System

Due to the stubborn nature of dynamic job shop scheduling problem, a novel ant colony coordination mechanism is proposed in this paper to search for an optimal schedule in dynamic environment. In ant colony coordination mechanism, the dynamic .job shop is composed of several autonomous ants. These ants coordinate with each other by simulating the ant foraging behavior of spreading pheromone on the trails, by which they can make information available globally, and further more guide ants make optimal decisions. The proposed mechanism is tested by several instances and the results confirm the validity of it.     

强电场下化学反应体系非线性介电行为研究

在强电场的作用下,化学反应体系的反应速率会发生改变,进而影响反应体系的平衡状态,然而其机理仍不清楚.本文从反应体系的介电特性出发,研究了强静电场与反应体系的相互作用.在只考虑二阶非线性响应时,对改进型的Smoluchowski方程进行勒让德多项式展开,推导出反应体系极化强度的一般表达式.同时利用异构反应讨论了具体的非线性变化,结果表明,极化过程中的二阶非线性项与极化强度之比与电场强度成正比,同时讨论并给出了该结果的适用范围.     

变色沙蜥(Phrynocephalus versicolor)的耐饥能力与食性研究

变色沙蜥于2004年7月采自新疆准噶尔盆地南缘沙漠地区，成体在夏季有较强的耐饥能力，在提供饮水条件下的耐饥能力为45～52d，平均为48.5d，在不提供饮水条件下的耐饥能力为17-24d左右，平均20．3d。以胃内容物分析法研究其食性，结果显示在夏季的食物主要是蚂蚁，占食物总量的84％，其次是步行虫，占11％。     

RMT-Based Urban Traffic Cross-Correlation Analysis and Its Application on Traffic Incident Impact Analyses

Cross-correlating traffic flow data at different intersections in an urban transportation network is important for understanding the collective behavior of constituents in a complex system and for predicting the risk of network-wide congestion. In this work, a Random Matrix Theory (RMT) based method is used to describe the collective behavior from massive traffic data sets. Nonrandom correlations between traffic flow series recorded in the Beijing road network occur both with and without detrending. The effect of the traffic load on the correlation patterns of network-wide traffic flows is analyzed using the RMT analysis of a simulated data set collected from Paramics. The RMT analysis is also used to evaluate the impact of incidents on the network-wide traffic status. Cluster analysis is used to find the largest cluster in the network which indicates the critical congestion caused by the incident. All the results show that RMT analyses are an effective method for investigating systematic interactions in urban transportation systems.     

Chaos in a long-term experiment with a plankton community

Mathematical models predict that species interactions such as competition and predation can generate chaos. However, experimental demonstrations of chaos in ecology are scarce, and have been limited to simple laboratory systems with a short duration and artificial species combinations. Here, we present the first experimental demonstration of chaos in a long-term experiment with a complex food web. Our food web was isolated from the Baltic Sea, and consisted of bacteria, several phytoplankton species, herbivorous and predatory zooplankton species, and detritivores. The food web was cultured in a laboratory mesocosm, and sampled twice a week for more than 2,300 days. Despite constant external conditions, the species abundances showed striking fluctuations over several orders of magnitude. These fluctuations displayed a variety of different periodicities, which could be attributed to different species interactions in the food web. The population dynamics were characterized by positive Lyapunov exponents of similar magnitude for each species. Predictability was limited to a time horizon of 15-30 days, only slightly longer than the local weather forecast. Hence, our results demonstrate that species interactions in food webs can generate chaos. This implies that stability is not required for the persistence of complex food webs, and that the long-term prediction of species abundances can be fundamentally impossible.     

网格资源的组织与发现研究

分析了网格资源的组织形式,阐述了蚁群算法的基本原理,提出了一种基于蚁群算法的网格资源发现方法.其中,将用户请求本体看作蚂蚁,查找的资源即搜索的目标视为食物,食物源就是存在搜索目标的节点.蚂蚁寻找食物的过程就是网格资源的发现过程.     

我国交通运输价格的现状和改革设想

分析了我国运价调改后的现状及存在的问题，认为运价长期扭曲是制约交通运输发展的主要因素。主张提高现行运价水平，实行多种运价形式，改革运价管理体制，建立运价与物价联动机制，并讨论了理顺运价比价关系等问题。     

基于交换机制的自适应蚁群聚类算法

在研究了基本聚类模型的基础上,模拟蚂蚁寻找食物源的行为,提出了一种基于蚁群最优化的自适应聚类分析的新方法。与之前的蚁群聚类不同,引入交换机制增强蚁群的觅食能力以提高聚类性能。该算法可以不用预先输入聚类数目,在仿真实验中该方法获得了比GCA算法和Kmeans算法更好的表现,表明这种基于交换机制的聚类算法具有较好的聚类性能。     

非线性不确定组合系统基于观测器的鲁棒分散镇定

讨论了一类组合系统的变结构鲁棒观测器的设计及这类系统基于估计状态反馈分散镇定问题。所设计的变结构观测器使得观测误差渐近趋于零 ,同时基于估计状态所设计的鲁棒分散控制器确保闭环系统是渐近稳定的     

Compartments revealed in food-web structure

Compartments in food webs are subgroups of taxa in which many strong interactions occur within the subgroups and few weak interactions occur between the subgroups. Theoretically, compartments increase the stability in networks, such as food webs. Compartments have been difficult to detect in empirical food webs because of incompatible approaches or insufficient methodological rigour. Here we show that a method for detecting compartments from the social networking science identified significant compartments in three of five complex, empirical food webs. Detection of compartments was influenced by food web resolution, such as interactions with weights. Because the method identifies compartmental boundaries in which interactions are concentrated, it is compatible with the definition of compartments. The method is rigorous because it maximizes an explicit function, identifies the number of non-overlapping compartments, assigns membership to compartments, and tests the statistical significance of the results. A graphical presentation reveals systemic relationships and taxa-specific positions as structured by compartments. From this graphic, we explore two scenarios of disturbance to develop a hypothesis for testing how compartmentalized interactions increase stability in food webs.     

非线性复合介质电导的有效介质近似

在强外场作用下,复合介质的电输运性能服从非线性的本构关系。复合介质非线性电导率的计算相当复要,在线性复合介质的理论框架内,已发展了多种有效介质近似方法。利用有效介质近似,可以导出计算有效输运系数的简洁的解析公式。只要颗粒浓度在逾渗临界点以外以及颗粒和杂质的输运系数之比为有限的情况下,有效介质近似的计算都可以给出相当可靠的理论结果,因此,对于工程应用来说,有效介质近似是十分有的工具。本文在非线性复合     

油气储运理论与技术进展

经过60年的发展,中国石油大学油气储运工程学科形成了油气长距离管道输送、多相管流与油气集输、油气储运设施安全与施工等特色鲜明的优势研究方向。近10多年来,伴随着中国油气储运行业的空前大发展以及随之而来的一系列技术挑战,本学科在这些研究领域开展了较系统深入的研究,在易凝高黏原油流变性与管道输送、天然气及成品油管道输送、油气水多相流动、油气水分离、多相混输系统流动保障、流动减阻机制、油气管道与集输系统节能、管道强度设计与安全评价、油气储运设施完整性管理、油气管道与地下储库施工等方面取得了一大批重要成果。较系统地总结了这些成果。总结本学科60年发展的经验,面向本领域重大工程技术问题,持之以恒地开展系统且深入的基础研究,仍是学科今后发展必须坚持的基本战略方针。     

Urban Transport and Sustainable Transport Strategies： A Case Study of Karachi, Pakistan

The uncontrolled growth in urbanization and motorization generally contributes to an urban land use and transportation system that is socially, economically, and environmentally unsustainable. This paper uses Karachi as a case study, which is the largest urban and economic centre of Pakistan, passing through an uncontrolled phase of rapid urbanization and motorization. The paper first reviews research related to sustainable transportation systems to comprehend the concept of sustainable development and transporta-tion. The paper then evaluates the existing transportation and infrastructure system, national transportation policies, and urban transportation projects to determine if the current paradigm is moving toward or away from sustainable transportation. Furthermore, the principles for sustainable urban transportation are devel-oped to see what significance national transportation policies have given to urban transportation from a sus-tainable transportation point of view. Finally some strategies are suggested, adoption of which may lead to a sustainable urban development and transportation system in Karachi.     

Many-body and correlation effects in semiconductors

Solids consist of 1022-1023 particles per cubic centimetre, interacting through infinite-range Coulomb interactions. The linear response of a solid to a weak external perturbation is well described by the concept of non-interacting 'quasiparticles' first introduced by Landau. But interactions between quasiparticles can be substantial in dense systems. For example, studies over the past decade have shown that Coulomb correlations between quasiparticles dominate the nonlinear optical response of semiconductors, in marked contrast to the behaviour of atomic systems. These Coulomb correlations and other many-body interactions are important not only for semiconductors, but also for all condensed-matter systems.     

CO_2管道运输系统鲁棒优化设计

CO_2管道运输系统是碳捕集、利用与封存(CCUS)技术的重要环节.将线性鲁棒优化方法应用于CO_2管道运输费用设计,建立其鲁棒优化模型,解决了管道运输系统不确定性优化问题,使优化结果更为合理.提出的方法合理配置了管道入口压力、管道内径、壁厚、中间泵站数量,降低了CO_2运输费用.仿真结果表明,与现有优化设计方法相比,运输系统鲁棒优化方法具有较强的适应能力,为管道安全运输提供了保障.