Coordination of multiple mobile robots with limited communication range in pursuit of single mobile target in cluttered environment

This paper addresses the problem of coordinating multiple mobile robots in searching for and capturing a mobile target,with the aim of reducing the capture time.Compared with the previous algorithms,we assume that the target can be detected by any robot and captured successfully by two or more robots.In this paper,we assume that each robot has a limited communication range.We maintain the robots within a mobile network to guarantee the successful capture.In addition,the motion of the target is modeled and incorporated into directing the motion of the robots to reduce the capture time.A coordination algorithm considering both aspects is proposed.This algorithm can greatly reduce the expected time of capturing the mobile target.Finally,we validate the algorithm by the simulations and experiments.

Performance analysis of optical burst switching node with limited wavelength conversion capabilities

The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.

Impacts of climate warming on hybrid zone movement： Geographically diffuse and biologically porous ＂species borders＂

The ecology and evolutionary biology of insect-plant associations has real- ized extensive attention, especially during the past 60 years. The classifications （categorical designations） of continuous variation in biodiversity, ranging from global patterns （e.g., lat- itudinal gradients in species richness/diversity and degree of herbivore feeding specialization） to localized insect-plant associations that span the biospectrum from polyphenisms, polymorphisms, biotypes, demes, host races, to cryptic species, remain academically contentious. Semantic and biosystematic （taxonomical） disagreements sometimes detract from more important ecological and evolutionary processes that drive diversification, the dynamics of gene flow and local extinctions. This review addresses several aspects of insect specialization, host-associated divergence and ecological （including ＂hybrid＂） speciation, with special reference to the climate warming impacts on species borders of hybridiz- ing swallowtail butterflies （Papilionidae）. Interspecific hybrid introgression may result in collapse of multi-species communities or increase species numbers via homoploid hybrid speciation. We may see diverging, merging, or emerging genotypes across hybrid zones, all part of the ongoing processes of evolution. Molecular analyses of genetic mosaics and genomic dynamics with ＂divergence hitchhiking＂, combined with ecological, ethological and physiological studies of＂species porosity＂, have already begun to unveil some answers for some important ecological/evolutionary questions. （i） How rapidly can host-associated divergence lead to new species （and why doesn＇t it always do so, e.g., resulting in ＂incom- plete＂ speciation）？ （ii） How might ＂speciation genes＂ function, and how/where would we find them？ （iii） Can oscillations from specialists to generalists and back to specialists help explain global diversity in herbivorous insects？ （iv） How could recombinant interspecific hybridization lead to divergence and speciation？ From ancient phytochemically defined angiosperm affiliations to recent and very local geographical mosaics, the Papilionidae （swallowtail butterflies） have provided a model for enhanced understanding of ecological patterns and evolutionary processes, including host-associated genetic divergence, ge- nomic mosaics, genetic hitchhiking and sex-linked speciation genes. Apparent homoploid hybrid speciation in Papilio appears to have been catalyzed by climate warming-induced interspecific introgression of some, but not all, species diagnostic traits, reflecting strong divergent selection （discordant）, especially on the Z （= X） chromosome. Reproductive isolation of these novel recombinant hybrid genotypes appears to be accomplished via a delayed post-diapause emergence or temporal isolation, and is perhaps aided by the thermal landscape. Changing thermal landscapes appear to have created （and may destroy） novel recombinant hybrid genotypes and hybrid species.

Annoying neighbors： Multi-scale distribution determinants of two sympatric sibling species of birds

We tested the role of interspecific competition in driving species distribution at multiple spatial scales using two sibl- ing species of Galerida larks （G cristata and G. theklae） in Morocco （sympatry）, Balearic islands （G theklae only） and Israel （G cristata only）. We first investigated regional-scale determinants by contrasting allopatric versus sympatric patterns in five distinct habitat types. We next focused on a single habitat used by both species, the coastal sand dunes. Dune quadrats were established along the Moroccan coast and completed by a quadrat in the nearest distinct landscape habitat. Poisson regressions were used to model Galerida counts together with ecological predictors as concerns the climate, topography, vegetation structure and soil gra- nulometry. At the local scale, both species preferred grey dunes over white sand dunes, and both were negatively affected by the abundance of the congeneric species in the dune. However, we found that G theklae tended to replace G. cristata in more arid sand dunes, even if the transition was not strictly clinal. Instead, the transition occurred when the surrounding landscape changed from coastal wetlands to bathas （grasslands with shrubs）, highlighting the importance of habitat composition at the landscape scale. The fact that G cristata used bathas in allopatry, but not in sympatry, suggested that the competitive environment contri- buted to determine sand dune occupancy. We suggest that landscape-level effects may be pivotal in explaining species distribu- tion not only at the local scale, by affecting the pool of potential immigrants, but also at the regional scale, by contributing to species＇ range limit [Current Zoology 61 （1）： 10-22, 2015].

Steady formation analysis onmulti-robot systems

In this paper,a controller is designed for a group of cooperative robots to achieve the stable displacements.Communication network among the robots is assumed unavailable and each robot can only measure the displacements relative to their neighbours.The controller will enable the robots to move to a predefined formation or a special formation under a suitable protocol which we will design.We will discuss the effect of different sizes of the multi-vehicle system and conduct simulations to verify the effectiveness of the proposed controller and the formation protocols.