Adaptive Event-Triggered Time-Varying Output Group Formation Containment Control of Heterogeneous Multiagent Systems

In this paper,a class of time-varying output group formation containment control problem of general linear hetero-geneous multiagent systems(MASs)is investigated under directed topology.The MAS is composed of a number of tracking leaders,formation leaders and followers,where two different types of leaders are used to provide reference trajectories for movement and to achieve certain formations,respectively.Firstly,compen-sators are designed whose states are estimations of tracking lead-ers,based on which,a controller is developed for each formation leader to accomplish the expected formation.Secondly,two event-triggered compensators are proposed for each follower to evalu-ate the state and formation information of the formation leaders in the same group,respectively.Subsequently,a control protocol is designed for each follower,utilizing the output information,to guide the output towards the convex hull generated by the forma-tion leaders within the group.Next,the triggering sequence in this paper is decomposed into two sequences,and the inter-event intervals of these two triggering conditions are provided to rule out the Zeno behavior.Finally,a numerical simulation is intro-duced to confirm the validity of the proposed results.

Evaluating Group Formation in Virtual Communities

In this paper, we are interested in answering the following research question: "Is it possible to form effective groups in virtual communities by exploiting trust information without significant overhead, similarly to real user communities?"In order to answer this question, instead of adopting the largely used approach of exploiting the opinions provided by all the users of the community(called global reputation), we propose to use a particular form of reputation, called local reputation. We also propose an algorithm for group formation able to implement the proposed procedure to form effective groups in virtual communities. Another interesting question is how to measure the effectiveness of groups in virtual communities. To this aim we introduce the index in a measure of the effectiveness of the group formation. We tested our algorithm by realizing some experimental trials on real data from the real world EPINIONS and CIAO communities, showing the significant advantages of our procedure w.r.t. another prominent approach based on traditional global reputation.

The Firstly Discovered Cosmic Spherules in Carbonaceous Siltstone from the Taizi Formation of the Mesoproterozoic Shennongjia Group,Central China

Objective Spherical micro-particles are often preserved in Precambrian sedimentary rocks. Finnish and Chinese scholars have previously discovered carbonaceous, siliceous or ferruginous spherules of out-space origin in the 1.6 Ga and 1.4 Ga sequence, respectively. The presence of spherules can record possible cosmic impact events. Also, cosmic spherules provide important information on the evolution of planets from outer space.

Decentralized content sharing in mobile ad-hoc networks:A survey

The evolution of smart mobile devices has significantly impacted the way we generate and share contents and introduced a huge volume of Internet traffic.To address this issue and take advantage of the short-range communication capabilities of smart mobile devices,the decentralized content sharing approach has emerged as a suitable and promising alternative.Decentralized content sharing uses a peer-to-peer network among colocated smart mobile device users to fulfil content requests.Several articles have been published to date to address its different aspects including group management,interest extraction,message forwarding,participation incentive,and content replication.This survey paper summarizes and critically analyzes recent advancements in decentralized content sharing and highlights potential research issues that need further consideration.

ResIoT:An IoT Social Framework Resilient to Malicious Activities

The purpose of the next internet of things(Io T)is that of making available myriad of services to people by high sensing intelligent devices capable of reasoning and real time acting.The convergence of Io T and multi-agent systems(MAS)provides the opportunity to benefit from the social attitude of agents in order to perform machine-to-machine(M2 M)cooperation among smart entities.However,the selection of reliable partners for cooperation represents a hard task in a mobile and federated context,especially because the trustworthiness of devices is largely unreferenced.The issues discussed above can be synthesized by recalling the well known concept of social resilience in Io T systems,i.e.,the capability of an Io T network to resist to possible attacks by malicious agent that potentially could infect large areas of the network,spamming unreliable information and/or assuming unfair behaviors.In this sense,social resilience is devoted to face malicious activities of software agents in their social interactions,and do not deal with the correct working of the sensors and other information devices.In this setting,the use of a reputation model can be a practicable and effective solution to form local communities of agents on the basis of their social capabilities.In this paper,we propose a framework for agents operating in an Io T environment,called Res Io T,where the formation of communities for collaborative purposes is performed on the basis of agent reputation.In order to validate our approach,we performed an experimental campaign by means of a simulated framework,which allowed us to verify that,by our approach,devices have not any economic convenience to performs misleading behaviors.Moreover,further experimental results have shown that our approach is able to detect the nature of the active agents in the systems(i.e.,honest and malicious),with an accuracy of not less than 11%compared to the best competitor tested and highlighting a high resilience with respect to some malicious activities.

Application of a Multi-Agent System (MAS) to Rational Credit Rating

A Multi-Agent System （ MAS ） is a promising approach to build complex system. This paper introduces the research of the Inner-Enterprise Credit Rating MAS （ IECRMAS）. To raise the rating accuracy, we not only consider the rating-target＇s information, but also focus on the evaluators＇ feature information and propose the rational rating-group formation algorithm based on an anti-bias measurement of the group. We also propose the rational rating individual, which consists of the evaluator and the assistant rating agent. A rational group formation protocol is designed to coordinate autonomous agents to perform the rating job.

Simultaneous ISAR imaging of group targets flying in formation

This paper proposes a novel inverse synthetic aperture radar（ISAR） imaging method based on second-order keystone transform（KT） and Sandglass transform for group targets flying in a formation with constant accelerated rectilinear motion in the same radar beam. First, range curvature and range walk of each sub-target among group targets are corrected by the second-order KT combined with the quadratic phase term compensation. After range alignment, the signals in each range frequency cell can be modelled as multiple chirp signals and then the Sandglass transform is utilized to cross-range imaging, which transforms the time–frequency distribution of the signals in each range frequency cell into beelines parallel to the slow time axis simultaneously. Finally, cross-range profiles of group targets in each range frequency cell are obtained via a projection of the perk of every scatterer in the two-dimensional accumulation plane onto the frequency axis. The advantage of the proposed method is that it can align range profiles of each sub-target simultaneously and image cross-range profiles directly without separating the returned signals, which simplifies the operation procedure. Simulation results are used to demonstrate the effectiveness of the proposed method.

An isolated compact galaxy triplet

We report the discovery of an isolated compact galaxy triplet SDSS J084843.45＋164417.3, which is first detected by the LAMOST spectral survey and then confirmed by a spectroscopic observation of the BFOSC mounted on the 2.16 meter telescope located at Xinglong Station, which is administered by National Astronomical Observatories, Chinese Academy of Sciences. It is found that this triplet is an iso- lated and extremely compact system, which has an aligned configuration and very small radial velocity dispersion. The member galaxies have similar colors and show marginal star formation activities. These results support the opinion that the compact triplets are well-evolved systems rather than hierarchically forming structures. This serendipitous discovery reveals the limitations of fiber spectral redshift surveys in studying such a compact system, and demonstrates the necessity of additional observations to complete the current redshift sample.

Dynamic grouping of heterogeneous agents for exploration and strike missions

The ever-changing environment and complex combat missions create new demands for the formation of mission groups of unmanned combat agents.This study aims to address the problem of dynamic construction of mission groups under new requirements.Agents are heterogeneous,and a group formation method must dynamically form new groups in circumstances where missions are constantly being explored.In our method,a group formation strategy that combines heuristic rules and response threshold models is proposed to dynamically adjust the members of the mission group and adapt to the needs of new missions.The degree of matching between the mission requirements and the group’s capabilities,and the communication cost of group formation are used as indicators to evaluate the quality of the group.The response threshold method and the ant colony algorithm are selected as the comparison algorithms in the simulations.The results show that the grouping scheme obtained by the proposed method is superior to those of the comparison methods.

On a Question of the Theory of Partially Composition Formations（Dedicated to Professor K.P. Shum on the occasion of his 70th birthday）

Let n 〉 0 and w be a non-empty set of primes. It is proved that the lattice of all τ-closed n-multiply ω-composition formations is inductive. It gives a positive answer to a question of Skiba asked in 2001 at the Gomel Algebraic Seminar.