Ecological consequences of chemically mediated prey perception

To locate food, mobile consumers in aquatic habitats perceive and move towards sources of attractive chemicals. There has been much progress in understanding how consumers use chemicals to identify and locate prey despite the elusive identity of odor signals and the complex effects of turbulence on chemical dispersion. This review highlights how integrative studies on behavior, fluid physics, and chemical isolation can be fundamental in elucidating mechanisms that regulate species composition and distribution. We suggest three areas where further research may yield important ecological insights. First, although basic aspects of stimulatory molecules are known, our understanding of how consumers identify prey from a distance remains poor, and the lack of studies examining the influence of distance perception on food preference may result in inaccurate estimation of foraging behavior in the field. Second, the ability of many animals to find prey is greatest in unidirectional, low turbulence flow environments, although recent evidence indicates a trade-off in movement speed versus tracking ability in turbulent conditions. This suggests that predator foraging mode may affect competitive interactions among consumers, and that turbulence provides a hydrodynamic refuge in space or time, leading to particular associations between predator success, prey distributions, and flow. Third, studies have been biased towards examining predator tracking. Current data suggest a variety of mechanisms prey may use to disguise their presence and avoid predation; these mechanisms also may produce associations between prey and flow environments. These examples of how chemical attraction may mediate interactions between consumers and their resources suggest that the ecology of chemically mediated prey perception may be as fundamental to the organization of aquatic communities as the ecology of chemical deterrence.     

细菌觅食优化算法的研究进展

细菌觅食优化算法是近年来发展起来的,基于大肠杆菌觅食行为模型的一种新型智能算法。它具有对初值和参数选择不敏感、鲁棒性强、简单易于实现,以及并行处理和全局搜索等优点。但其在应用过程中存在精度不够高、收敛速度不够快的缺点。文中首先对细菌觅食优化算法的基本原理及操作流程进行介绍,并概述了国内外学者在这一领域的研究现状,接着分析了算法三大主要操作存在的问题,然后探讨了算法的改进和应用,最后分析了算法未来的研究方向。     

基于细菌迁徙的自适应果蝇优化算法

针对果蝇优化算法的早熟收敛问题,提出了一种新的基于细菌迁徙的自适应果蝇优化算法。该算法在运行过程中根据进化停滞步数的大小自适应地引入细菌迁徙操作,提高算法跳出局部极值的能力;并且对每个个体根据适应值大小赋予不同的自适应迁徙概率,避免了迁徙可能带来的解退化的问题。对几种经典函数的测试结果表明,新算法具有更好的全局搜索能力,在收敛速度、收敛可靠性及收敛精度上比果蝇优化算法有较大的提高。     

改进的菌群算法研究

为了提高菌群寻优算法（ Bacterial Foraging Optimization, BFO）的搜索能力和解决多峰值复杂适应度函数模型避免过早收敛的问题,文中对原始菌群算法进行改进,提出多峰值菌群算法。将寻优过程分成两个时期,前期和原始菌群算法相同,在菌群收敛的后期,加入峰值数目和区间的判断,将区间编号,保证区间内部单峰值;然后在区间内部迭代运行菌群搜索,独立寻优,在多峰值和较复杂模型的情况下进行研究和评估。实验表明,在收敛速度、收敛稳定性和寻找全局最优方面均优于原始菌群算法。     

Supporting geographically-aware web document foraging and sensemaking

This paper reports on the development and application of strategies and tools for geographic information seeking and knowledge building that leverages unstructured text resources found on the web. Geographic knowledge building from unstructured web sources starts with web document foraging during which the quantity, scope and diversity of web-based information create incredible cognitive burdens on an analyst’s or researcher’s ability to judge information relevancy. Determining information relevancy is ultimately a process of sensemaking. In this paper, we present our research on visually supporting web document foraging and sensemaking. In particular, we present the Sense-of-Place (SensePlace) analytic environment. The scientific goal of SensePlace is to visually and computationally support analyst sensemaking with text artifacts that have potential place, time, and thematic relevance to an analytical problem through identification and visual highlighting of named entities (people, places, times, and organizations) in documents, automated inference to determine document relevance using stored knowledge, and a visual interface with coupled geographic map, timeline, and concept graph displays that are used to contextualize the contexts of potentially relevant documents. We present the results of a case study analysis using SensePlace to uncover potential population migration, geopolitical, and other infectious disease dynamics drivers for measles and other epidemics in Niger. Our analysis allowed us to demonstrate how our approach can support analysis of complex situations along (a) multi-scale geographic dimensions (i.e., vaccine coverage areas), (b) temporal dimensions (i.e., seasonal population movement and migrations), and (c) diverse thematic dimensions (effects of political upheaval, food security, transient movement, etc.).     

Scheduling and development support in the Scavenger cyber foraging system

Cyber foraging is a pervasive computing technique where small mobile devices offload resource intensive tasks to stronger computing machinery in the vicinity.One of the main challenges within cyber foraging is that it is very difficult to develop cyber foraging enabled applications. An application using cyber foraging is working with mobile, distributed and, possibly, parallel computing; fields within computer science notoriously hard for programmers to grasp.This paper presents Scavenger—a cyber foraging system supporting easy development of mobile cyber foraging applications, while still delivering efficient, mobile use of remote computing resources through the use of a custom built mobile code execution environment and a new adaptive, dual-profiling scheduler.     

嵌入趋化算子的PSO算法及其在多阈值分割中的应用

针对标准粒子群优化(Particle Swarm Optimization,PSO)算法在优化选择多阈值时易陷入局部最优等问题,提出一种嵌入趋化算子的PSO算法。首先针对标准PSO算法具有较强的全局寻优能力但局部搜索能力较差,而细菌觅食优化(Bacterial Foraging Optimization,BFO)算法具有较强的局部搜索能力的特点,将BFO算法中具有较强局部搜索能力的趋化算子嵌入到PSO算法中,形成一种嵌入趋化算子的PSO算法(Chemotaxis Operator embedded PSO,COPSO),以此优势互补,使COPSO算法既有较强的全局搜索能力,又有较强的局部搜索能力。最后将COPSO算法用于最大熵多阈值图像分割中,得到最佳阈值向量。实验结果表明:与标准的PSO、BFO和GA算法相比,该算法具有更好的优化效果和更短的寻优时间。     

用于指数熵多阈值分割的改进细菌觅食算法

针对图像多阈值分割中阈值搜索是有序正整数规划的特点,提出了一种用于指数熵多阈值分割的改进细菌觅食优化(Improved Bacterial Foraging Optimization,IBFO)算法。首先,将标准的细菌觅食优化(Standard Bacterial Foraging Optimization,SBFO)算法的趋化算子改成动态趋化算子以增强趋化操作的自适应性;然后,将SBFO中的迁徙算子替换成混合随机和动态的迁徙算子,将迁徙过程划分为两个阶段,第一阶段为随机迁徙,目的是增强全局搜索能力,第二阶段为动态局部迁徙,目的是提高局部搜索能力;随后,丢弃SBFO中的感应机制以便加快运行速度;最后,将IBFO算法进一步修改以满足有序正整数规划的要求,并将其应用于指数熵多阈值分割方法中。图像分割实验结果表明,与SBFO,MBFO和IPSO算法相比,提出的IBFO方法不仅优化效果更好,而且运行速度更快。     

广义菌群优化算法

为提高菌群优化算法的性能,将群体聚集机制和自适应策略集成到趋药性操作中,取消聚集操作,构造出新的趋化操作,在趋化循环中引入自适应扩散机制,提高其克服“早熟”的能力,重新定义健康度,减少计算复杂性,得到了一种新的群体智能优化方法—广义菌群优化算法(GBFO, Generalized Bacterial Foraging Optimization)。通过10个复杂Benchmark函数的计算进行算法性能测试,并与几个典型的算法进行了实验比较,结果表明,GBFO算法在搜索能力和稳定性、求解质量和效率等方面优于其他典型算法的比率分别达到80%~90%,70%~80%,验证了该算法的优越性能。     

基于BFOA算法的配电网DG选址定容方法

发展分布式能源系统对于实现的“碳达峰”和“碳中和”,提升可再生能源的开发利用具有重要意义。提出一种基于细菌觅食优化算法（BFOA）的配电网分布式电源（DG）选址定容方法。建立以配电网的功率损耗指数、电压偏差以及安装分布式电源所降低的净运行成本最小为目标的数学模型及约束条件,提出损耗敏感系数（LSF）来确定DG安装位置,并引用BFOA算法求解DG的最佳容量。仿真表明,相对于传统优化算法,BFOA算法在模型求解时间和收敛速度上具有明显优势,所提规划方法能够最大限度地降低功率损耗和运行成本,并提高系统的电压稳定性。