改进的细菌觅食优化算法及其在框架结构设计中的应用

在细菌觅食算法(bacterial foraging algorithm,BFA)基本原理的基础上,结合“和声搜索”算法,提出了一种改进的细菌觅食算法,并应用于框架结构优化.采用该优化算法分别对一单跨8层框架和双跨5层框架结构进行离散变量的质量优化设计,并与细菌觅食算法的计算结果进行了比较.计算结果表明改进的细菌觅食算法应用在结构优化中具有较好的收敛速度和精度,可应用于工程结构的优化设计.     

Social information use and the evolution of unresponsiveness in collective systems

Animal groups in nature often display an enhanced collective information-processing capacity. It has been speculated that natural selection will tune this response to be optimal, ensuring that the group is reactive while also being robust to noise. Here, we show that this is unlikely to be the case. By using a simple model of decision-making in a dynamic environment, we find that when individuals behave rationally and are subject to selection based on their accuracy, optimality of collective decision-making is not attained. Instead, individuals overly rely on social information and evolve to be too readily influenced by their neighbours. This is due to a classic evolutionary conflict between individual and collective interest. The result is a sub-optimal system that is poised on the cusp of total unresponsiveness. Individuals in the evolved group exhibit delayed reactions to changes in the environment, before responding with rapid, socially reinforced transitions, reminiscent of familiar human and animal social systems (markets, stampedes, fashions, etc.). Our results demonstrate that behaviour of this type may not be pathological, but instead could represent an evolutionary attractor for such collective systems.     

Solving cell formation and task scheduling in cellular manufacturing system by discrete bacteria foraging algorithm

We consider a joint decision model of cell formation and task scheduling in cellular manufacturing system under dual-resource constrained (DRC) setting. On one hand, machines and workers are multi-functional and/or multi-skilled, and they are grouped into workstations and cells. On the other hand, there is a processing sequence among operations of the parts which needs to be dispatched to the desirable workstations for processing. Inter-cell movements of parts can reduce the processing times and the makespan but will increase the inter-cell material handling costs. The objective of the problem is to minimise the material handling costs as well as the fixed and operating costs of machines and workers. Due to the NP-hardness of the problem, we propose an efficient discrete bacteria foraging algorithm (DBFA) with elaborately designed solution representation and bacteria evolution operators to solve the proposed problem. We tested our algorithm using randomly generated instances with different sizes and settings by comparing with the original bacteria foraging algorithm and a genetic algorithm. Our results show that the proposed DBFA has better performance than the two compared algorithms with the same running time.     

Mesoscale fronts as foraging habitats: composite front mapping reveals oceanographic drivers of habitat use for a pelagic seabird

The oceanographic drivers of marine vertebrate habitat use are poorly understood yet fundamental to our knowledge of marine ecosystem functioning. Here, we use composite front mapping and high-resolution GPS tracking to determine the significance of mesoscale oceanographic fronts as physical drivers of foraging habitat selection in northern gannets Morus bassanus. We tracked 66 breeding gannets from a Celtic Sea colony over 2 years and used residence time to identify area-restricted search (ARS) behaviour. Composite front maps identified thermal and chlorophyll-a mesoscale fronts at two different temporal scales—(i) contemporaneous fronts and (ii) seasonally persistent frontal zones. Using generalized additive models (GAMs), with generalized estimating equations (GEE-GAMs) to account for serial autocorrelation in tracking data, we found that gannets do not adjust their behaviour in response to contemporaneous fronts. However, ARS was more likely to occur within spatially predictable, seasonally persistent frontal zones (GAMs). Our results provide proof of concept that composite front mapping is a useful tool for studying the influence of oceanographic features on animal movements. Moreover, we highlight that frontal persistence is a crucial element of the formation of pelagic foraging hotspots for mobile marine vertebrates.     

An information trail model for capturing human behaviour in artefact creation and use in complex work systems

This article presents an information trail model. The model is a method for uncovering information transformation using artefacts in complex work systems. We use a patient care scenario in a hospital emergency department to illustrate theoretical, methodological and design elements of the model. In a complex system, humans create and manage complexity, a paradox. The information trail model proposes that humans manage the paradox by creating and evolving artefacts and information cues. They organise purposefully through self-organisation and stigmergical behaviour. Information trail model states that humans leave trails of information as signs or symbols, and the piecing together and transformation of which will lead to final goals. Information trails contain work attributes and strategies, which can be utilised in work system design.     

Determinants of internal and external R&D offshoring: evidence from Spanish firms

This paper analyses the determinants of R&D offshoring of Spanish firms using information from the Panel of Technological Innovation. We find that being an exporter, international technological cooperation, continuous R&D engagement, applying for patents, being a foreign subsidiary, and firm size are factors that positively affect the decision to offshore R&D. In addition, we find that a lack of financing is an obstacle relatively more important for independent firms than for firms that belong to business groups. For these latter, we also obtain that the factors that influence the decision to offshore R&D differ depending on whether the firm purchases the R&D services within the group or through the market: a higher degree of importance assigned to internal sources of information for innovation as compared to market sources increases (decreases) the probability of R&D offshoring only through the group (market).     

Optoelectronics — past,present, and future

Considerable progress has been made in the field of optoelectronics in the last thirty years. The two principal drivers for this progress have been the invention of the laser and low-loss optical fibres. But what is optoelectronics? Optoelectronics is more than just a marriage of electronics and optics. It represents the higher order integration of technical achievements in electronics and photonics to allow one to chose what, where, when, and how to address both old and new problems and opportunities for increasing customer satisfaction in the areas of information movement and management. I will review the progress in the field and share my insights into where the future lies. The important question no longer is if optics will replace electronics in many of the technologies underlying information movement and management; it is when and to what degree. The limitation no longer arises from the technical capabilities, it comes from economics and social values provided by the increased capabilities in communications and computers.     

Relationships between multiaxial stress states and internal fracture patterns in sphere-impacted silicon carbide

Internal fracture patterns developed in silicon carbide cylindrical targets as a result of dynamic indentation (63–500 m/s) by tungsten carbide spheres are defined. Microscopy of recovered and sectioned targets delineate into three regions, each associated with distinct cracking modes, i.e., shallow cone macrocracking at and near the impact surface, steep interior cone macrocracks that radiate into the target from the impact region and local grain-scale microcracking directly underneath the impact region. The observed fracture patterns are found to maintain a noticeable degree of self-similarity upto the impact velocity of 500 m/s. Linear elastic analysis of the full (surface and interior) stress field developed under static (Hertz) contact loading delineate the target into four regions, based on the number of principal stresses that are tensile (none, 1, 2 or all 3). A strong correlation is found between the principal stress conditions within each region and the forms of cracking, their locations and orientations present therein. This correlation has a number of implications, including non-interaction of crack systems, which are discussed. Illustrative linear elastic fracture mechanics analyses are performed for three regions, and calculated and observed macrocrack lengths are found to be in reasonable agreement.     

Identifying and classifying force-generation strategies for one-hand isometric force exertion tasks with bracing availability

Obstructions within a task environment provide opportunities for people to brace themselves with the non-task hand, thigh, or other body part. Previous research has shown that bracing can increase one-hand isometric force-exertion capability in standing tasks. The current laboratory study examined the patterns of force on the bracing surfaces as a function of task and human characteristics. Twenty-two men and women exerted static forces with their right hands. Bracing opportunities were provided at the thigh, contralateral hand, or both. Using the task hand force as a reference, bracing forces were decomposed into opposing and non-opposing components and normalised relative to task hand force magnitude. Five distinct patterns of bracing force, termed force-generation strategies (FGSs), emerged.     

Identification of information sources and citation patterns in the field of reciprocating internal combustion engines

Processes and technology of reciprocating internal combustion engines (ICE) constitute a research field whose characteristics regarding information production and diffusion are determined by multidisciplinarity, the existence of pseudo-technical literature and the influence of confidentiality on the presentation of research outputs. The objective of this study is to provide a quantitative and objective basis for the evaluation of research in this field. This has been accomplished by identifying the most productive journals and the most cited sources, using the SCI and citation analysis. From this analysis, core journals have been identified, showing that their importance in this research area does not correlate with their impact factor. Moreover, conference proceedings (particularly those published by the Society of Automotive Engineers) are shown to be the most important information source in this field. This revised version was published online in June 2006 with corrections to the Cover Date.     

SSCM:一种语义相似度计算方法

分析了实例多重继承和实例属性层次关系对实例相似性的影响,针对原有的实例语义相似度计算方法的不足,提出了一种语义相似度计算方法SSCM,该方法综合考虑了实例多重继承关系和属性及属性值的层次关系,并利用继承关系的树状结构特点对计算过程进行了优化.实验表明,该方法在本体知识库的多种组成情况下,均能有效提高语义相似度计算的准确率.在实例多重继承关系相对复杂的情况下,准确率提高更加明显.     

架构和模式在水声信息流仿真软件中的应用

水声信息流仿真软件系统涉及多目标、多声纳以及多变的海洋环境．仿真软件的复用性是现代软件工程的重要性能指标．针对系统开放性的特点，在领域分析模型的基础上，采用了面向对象方法设计仿真软件模型．为了满足软件多层次复用的需求，应用软件架构技术和设计模式设计仿真软件．根据水声信息流仿真软件需求，系统划分为四层结构；按功能，层又可分解为包．可复用的设计模式用于设计不同层和包中类之间的关系．提出的仿真软件模型具有良好的可扩充性与可复用性．     

形状记忆合金中的马氏体变体在外场下的再取向和再分布机制(英文)

利用相场方法研究了马氏体变体在循环应力作用下再取向和再分布的微观机制。模拟结果表明,随着外应力的增加,在孪晶界面会出现母相的形核和长大,以此实现变体间的转化,这是3种变体转化为2种变体的主要再取向机制;卸载后消失的变体在孪晶界面重新形核并长大以完成系统内微观组织的再分布。在Mn-Cu合金中这种机制是控制循环载荷下形状记忆效应产生的主要机制。     

Spiral bacterial foraging optimization method: Algorithm,evaluation and convergence analysis

A biologically-inspired algorithm called Spiral Bacterial Foraging Optimization (SBFO) is investigated in this article. SBFO, previously proposed by the same authors, is a multi-agent, gradient-based algorithm that minimizes both the main objective function (local cost) and the distance between each agent and a temporary central point (global cost). A random jump is included normal to the connecting line of each agent to the central point, which produces a vortex around the temporary central point. This random jump is also suitable to cope with premature convergence, which is a feature of swarm-based optimization methods. The most important advantages of this algorithm are as follows: First, this algorithm involves a stochastic type of search with a deterministic convergence. Second, as gradient-based methods are employed, faster convergence is demonstrated over GA, DE, BFO, etc. Third, the algorithm can be implemented in a parallel fashion in order to decentralize large-scale computation. Fourth, the algorithm has a limited number of tunable parameters, and finally SBFO has a strong certainty of convergence which is rare in existing global optimization algorithms. A detailed convergence analysis of SBFO for continuously differentiable objective functions has also been investigated in this article.     

Emergence of coherent structures and large-scale flows in motile suspensions

The emergence of coherent structures, large-scale flows and correlated dynamics in suspensions of motile particles such as swimming micro-organisms or artificial microswimmers is studied using direct particle simulations. A detailed model is proposed for a slender rod-like particle that propels itself in a viscous fluid by exerting a prescribed tangential stress on its surface, and a method is devised for the efficient calculation of hydrodynamic interactions in large-scale suspensions of such particles using slender-body theory and a smooth particle-mesh Ewald algorithm. Simulations are performed with periodic boundary conditions for various system sizes and suspension volume fractions, and demonstrate a transition to large-scale correlated motions in suspensions of rear-actuated swimmers, or Pushers, above a critical volume fraction or system size. This transition, which is not observed in suspensions of head-actuated swimmers, or Pullers, is seen most clearly in particle velocity and passive tracer statistics. These observations are consistent with predictions from our previous mean-field kinetic theory, one of which states that instabilities will arise in uniform isotropic suspensions of Pushers when the product of the linear system size with the suspension volume fraction exceeds a given threshold. We also find that the collective dynamics of Pushers result in giant number fluctuations, local alignment of swimmers and strongly mixing flows. Suspensions of Pullers, which evince no large-scale dynamics, nonetheless display interesting deviations from the random isotropic state.     

一类禁忌算法及其在医学图像配准中的应用

针对脑功能成像中图像配准的优化模型,提出了一种基于记忆的禁忌算法。数值试验表明该算法是可行的、有效的。应用此算法求解医学图像配准的优化模型,可实现时间序列脑功能图像的高精度配准。     

On the Bullwhip Avoidance Phase: supply chain collaboration and order smoothing

This paper provides an assessment of the impact of collaboration and smoothing replenishment rules on supply chain operational performance and customer service level. Three supply chain configurations (i.e. Traditional, Information Exchange and Synchronised) in which orders are generated by smoothing (S, R) inventory control policies are studied for different proportional controllers. A supply chain stress test is performed through a sudden and intense change in demand. A structured and extended supply chain assessment framework is adopted. The main conclusions of this paper are the following. (i) The impact of Supply Chain Collaboration on overall supply chain performance is greater than that of order smoothing. Order smoothing mitigates the bullwhip effect, but it may have a negative impact on customer service. Supply Chain Collaboration mitigates the bullwhip effect, provides inventory stability, limits lumpy orders and enhances customer service level. (ii) The negative effect on customer service level of order smoothing is almost eliminated in synchronised supply chains.     

Survey of the annual technical reports on patent information activities in the year 2000 (part 1: A–J)

The activities in the year 2000 of some 24 intellectual property offices and organisations world wide in the field of patent information are summarised. The summary is presented under nine standard headings, as far as relevant, for each country. Activity varies enormously from just a handful of applications through to CA (39K), DE (62K), and EP (143K), the numbers continuing to increase significantly in most countries. This is the first of two parts, covering 50 countries and organisations; this part deals with those having WIPO codes starting A–I, and Jamaica.