Three-dimensional impact angle constrained distributed cooperative guidance law for anti-ship missiles

This paper investigates the problem of distributed cooperative guidance law design for multiple anti-ship missiles in the three-dimensional(3-D)space hitting simultaneously the same target with considering the desired terminal impact angle constraint.To address this issue,the problem formulation including 3-D nonlinear mathematical model description,and communication topology are built firstly.Then the consensus variable is constructed using the available information and can reach consensus under the proposed acceleration command along the line-of-sight(LOS)which satisfies the impact time constraint.However,the normal accelerations are designed to guarantee the convergence of the LOS angular rate.Furthermore,consider the terminal impact angle constraints,a nonsingular terminal sliding mode(NTSM)control is introduced,and a finite time convergent control law of normal acceleration is proposed.The convergence of the proposed guidance law is proved by using the second Lyapunov stability method,and numerical simulations are also conducted to verify its effectiveness.The results indicate that the proposed cooperative guidance law can regulate the impact time error and impact angle error in finite time if the connecting time of the communication topology is longer than the required convergent time.

Distributed Cooperative Secondary Voltage Control in an Unbalanced Microgrid

The negative-sequence reactive power-conductance(Q^(−)-G) droop control strategy is a conventional method to compensate for the output unbalanced voltages in an islanded MG.Nevertheless, the conflict between unbalanced voltage compensation and negative-sequence reactive power sharing, caused bythe impedance mismatching of distribution lines and distributedgenerators, has not been solved only by Q^(−)-G droop control.In this paper, a distributed cooperative secondary unbalancedvoltage control strategy is proposed to decrease the outputvoltage unbalance factor (VUF) of each droop-controlled DG,as well as to further enhance the negative-sequence reactivepower sharing effectiveness among DGs by properly shiftingup and down the Q^(−)-G droop characteristics of each DG.An algorithm for adaptive VUF weight coefficient is proposedto better suppress VUF under severe imbalance conditions.Furthermore, a negative-sequence small-signal model of an MGunder an unbalanced condition, considering the communicationdelay time of the proposed SUVC, is established to analyze thesystem’s stability and transient performance under the influenceof some critical parameters. Finally, the effectiveness of theproposed strategy is validated by the simulation results froma real-time emulator of StarSim HIL.

Cooperative Distributed Beamforming Design for Multi-RIS Aided Cell-Free Systems

Cell-free systems significantly improve network capacity by enabling joint user service without cell boundaries,eliminating intercell interference.However,to satisfy further capacity demands,it leads to high-cost problems of both hardware and power consumption.In this paper,we investigate multiple reconfigurable intelligent surfaces(RISs)aided cell-free systems where RISs are introduced to improve spectrum efficiency in an energy-efficient way.To overcome the centralized high complexity and avoid frequent information exchanges,a cooperative distributed beamforming design is proposed to maximize the weighted sum-rate performance.In particular,the alternating optimization method is utilized with the distributed closed-form solution of active beamforming being derived locally at access points,and phase shifts are obtained centrally based on the Riemannian conjugate gradient(RCG)manifold method.Simulation results verify the effectiveness of the proposed design whose performance is comparable to the centralized scheme and show great superiority of the RISs-aided system over the conventional cellular and cell-free system.

Distributed Cooperative Coverage of Mobile Robots with Consensus-Based Connectivity Estimation

This paper deals with the discrete-time connected coverage problem with the constraint that only local information can be utilized for each robot. In such distributed framework, global connectivity characterized by the second smallest eigenvalue of topology Laplacian is estimated through introducing distributed minimal-time consensus algorithm and power iteration algorithm. A self-deployment algorithm is developed to disperse the robots with the precondition that the estimated second smallest eigenvalue is positive at each time-step. Since thus connectivity constraint does not impose to preserve some certain edges, the self-deployment strategy developed in this paper reserves a sufficient degree of freedom for the motion of robots. Theoretical analysis demonstrates that each pair of neighbor robots can finally reach the largest objective distance from each other while the group keeps connected all the time, which is also shown by simulations.

Distributed cooperative deployment strategy in multi-UAVs assisted heterogeneous networks

Unmanned aerial vehicle base stations(UAV-BSs)can provide a fast network deployment scheme for heterogeneous networks.However,unmanned aerial vehicle(UAV)has limited capability and cannot assist the base station(BS)well.The ability of a UAV to assist the BSs is limited,and the cluster deployment relies on the leading UAV.The dispersive deployment of multiple UAVs(multi-UAVs)need a macro base station(MBS)to determine their positions to prevent collisions or interference.Therefore,a distributed cooperative deployment scheme is proposed for UAVs to solve this problem.The scheme can increase the ability of UAVs to assist users and reduce the pressure on BSs to deploy UAVs.Firstly,the randomly distributed users are pre-clustered.Then the placement problem was modeled as a circle expansion problem and a pre-clustering radius expansion algorithm was proposed.Under the constraint of users'data rates,it provides services for more users.Finally,the proposed algorithm was compared with the density-aware placement algorithm.The simulation results show that the proposed algorithm can provide services for more users and improve the coverage rate of users while ensuring the data rates.

Distributed cooperative formation of multiple mobile agents with preserved connectivity

This paper investigates distributed cooperative formation control of a group of multiple mobile agents with a virtual leader,where information exchange among agents is modeled by the group topology,and the states of the virtual leader are known only by parts of the agents.We develop a class of distributed formation control laws with similar form.The steered group is proved to achieve the desired formation objectives as long as the intersection of the initial communication topology and the formation goal topology is connected.This requirement of connectivity can be easily achieved by many practical applications;consequently,our developed distributed control laws are effective and feasible.Furthermore,for the developed control laws,we show the influence of different information flow graph of agents on the convergence rate and robustness to node and connection failures.

Substation area joint defensive protection strategy based on distributed cooperative all-in-one device

Integration of primary and secondary devices are impelled by the development of smart grid. Based on the ideology of primary and secondary device integration, an all-in-one device and its concept, configuration and function are proposed. Then, an all-in-one device framework of distributed substation area protection is proposed. Point-topoint model and virtual local area network(VLAN) based network-to-network model are adopted in this framework.The dual redundancy on hardware and software level is realized by modularization and protection information mirroring storage/overwriting. Considering the fact that the sampling, logic judgment and information sharing processes of protection may fail in atrocious conditions, a distributed cooperative all-in-one device cluster based substation area joint defensive protection strategy is proposed. The adaptability of sectional component failure in secondary system is strengthened by reusing module function, setting value mirroring storage and dynamic load balancing computing ability to constitute strong intelligent outdoor secondary device integrated network. Finally, the simulation examples based on EPOCHS which consider various system failure conditions are presented to verify the validity and rationality of the proposed architecture and strategy.

Distributed cooperative voltage control based on curve-fitting in active distribution networks

This study investigates a hybrid hierarchical multi-agent system for distributed cooperative voltage control in active distribution networks. The hybrid hierarchical multi-agent system adopts on-load tap-changing(OLTC) agents for the distribution transformers and feeder control section(FCS) agents for the distributed generators(DGs). The objective is to minimize the voltage deviations over the network. The FCS agents also have the objective of minimizing reductions in DG power output. A least squares method is used for curve fitting to achieve the two objectives. The OLTC agent receives voltage information from the FCS agents to evaluate the state of the voltage in each feeder and the distribution network and cooperates with the FCS agents to control the voltage of the network.The FCS agents exchange the fitted curve parameters and basic information on the DGs with other agents to achieve the objectives. The effectiveness of the proposed distributed cooperative voltage control scheme is verified through simulations. Depending on the network voltages obtained by the OLTC agent, different operations are executed to prevent voltage limit violations and to minimize the voltage deviations and reductions in the DG power outputs.

Distributed Stretching Control of Web Production System

The stretching process,as a key phase of web production system,pursues the target velocities of rollers and the web tensions of spans between the successive rollers to guarantee proper stretching ratios. This requires the stable velocities and velocity ratios of large number rollers separated throughout the workshop. To this goal,a distributed cooperative controller is designed to coordinate the velocities of the rollers to the desired values as well as the target ratios between the upper and lower rollers. During the whole evolution,only the neighbor rollers can exchange the working information,and neither global information nor central controller is required. It is proven that all the rollers asymptotically achieve the desired velocity ratios via the proposed control law,which is also demonstrated by numerical simulation.

Log Likelihood Ratio-Based Relaying for Distributed Turbo Codes

A distributed turbo codes（ DTC） scheme with log likelihood ratio（ LLR）-based threshold at the relay for a two-hop relay networks is proposed. Different from traditional DTC schemes,the retransmission scheme at the relay,where imperfect decoding occurs,is considered in the proposed scheme. By employing a LLR-based threshold at the relay in the proposed scheme,the reliability of decoder-LLRs can be measured. As a result,only reliable symbols will be forwarded to the destination and a maximum ratio combiner（ MRC） is used to combine signals received from both the source and the relay. In order to obtain the optimal threshold at the relay,an equivalent model of decoderLLRs is investigated,so as to derive the expression of the bit error probability（ BEP） of the proposed scheme under binary phase shift keying（ BPSK） modulation. Simulation results demonstrate that the proposed scheme can effectively mitigate error propagation at the relay and also outperforms other existing methods.

Distributed Step-by-step Finite-time Consensus Design for Battery Energy Storage Devices with Droop Control

As all generators are distributed in different areas among large scale power systems,the cooperative manipulation of the multi-generator system cannot operate well without consideration of the distance information of the generators.A distributed step-by-step finite-time consensus scheme for the heterogeneous battery energy storage system(BESS)is proposed in this paper,where the coordinated consensus can come into reality within a limited time,which is appealing for the electrical engineering community.To be concrete,at first,all BESSs are classified into several clusters according to their locations,and in each cluster,there is an active leader in charge of information receiving from outside.Then,in order to coordinate the multi BESSs,five inputs,which are function oriented,were used to achieve energy level balancing,active/reactive power sharing,and the consensus of voltage and frequency of the multi BESSs.Furthermore,the frequency and voltage restoration to the nominal values of the main grid were made possible by the introduction of a virtual leader,which is actually an external leader.Compared with the centralized methods,this control scheme is entirely distributed,and each BESS only utilizes the information of its own and its neighbors.In addition,this control is robust to the load perturbation and the plug-and-play of the communication topology.Finally,some simulation experiments are executed on the modified IEEE 57-bus system to verify the suggested scheme.

Impact of Distribution Fairness Degree and Entanglement Degree on Cooperation

We explore the impact of distributional fairness degree and entanglement degree on the cooperation between different players by investigating a modified prisoner＇s dilemma game. We not only introduce a new concept of distributional fairness degree, but also obtain the cooperation conditions for overcoming dilemma in terms of fairness and entanglement inequalities. It is demonstrated that distributional fairness can be of fundamental importance to promote cooperation with the help of quantum entanglement.

A Privacy-preserving Algorithm for AC Microgrid Cyber-physical System Against False Data Injection Attacks

A new privacy-preserving algorithm based on the Paillier cryptosystem including a new cooperative control strategy is proposed in this paper, which can resist the false data injection(FDI) attack based on the finite-time control theory and the data encryption strategy. Compared with the existing algorithms, the proposed privacy-preserving algorithm avoids the direct transmission of the ciphertext of frequency data in communication links while avoiding complex iterations and communications. It builds a secure data transmission environment that can ensure data security in the AC microgrid cyber-physical system(CPS). This algorithm provides effective protection for AC microgrid CPS in different cases of FDI attacks. At the same time, it can completely eliminate the adverse effects caused by the FDI attack. Finally, the effectiveness, security, and advantages of this algorithm are verified in the improved IEEE 34-node test microgrid system with six distributed generators(DGs) in different cases of FDI attacks.

ForkXplorer:an approach of fork summary generation

Pull-based development has become an important paradigm for distributed software development.In this model,each developer independently works on a copied repository(i.e.,a fork)from the central repository.It is essential for developers to maintain awareness of the state of other forks to improve collaboration efficiency.In this paper,we propose a method to automatically generate a summary of a fork.We first use the random forest method to generate the label of a fork,i.e.,feature implementation or a bug fix.Based on the information of the fork-related commits,we then use the TextRank algorithm to generate detailed activity information of the fork.Finally,we apply a set of rules to integrate all related information to construct a complete fork summary.To validate the effectiveness of our method,we conduct 30 groups of manual experiment and 77 groups of case studies on Github.We propose Fea_(avg)to evaluate the performance of Fea_(avg)the generated fork summary,considering the content accuracy,content integrity,sentence fluency,and label extraction accuracy.The results show that the average of of the fork summary generated by this method is 0.672.More than 63%of project maintainers and the contributors believe that the fork summary can improve development efficiency.

Strategically supported cooperation in dynamic games with coalition structures

The problem of strategic stability of long-range cooperative agreements in dynamic games with coalition structures is investigated. Based on imputation distribution procedures, a general theoretical framework of the differential game with a coalition structure is proposed. A few assumptions about the deviation instant for a coalition are made concerning the behavior of a group of many individuals in certain dynamic environments.From these, the time-consistent cooperative agreement can be strategically supported by ε-Nash or strong ε-Nash equilibria. While in games in the extensive form with perfect information, it is somewhat surprising that without the assumptions of deviation instant for a coalition, Nash or strong Nash equilibria can be constructed.