Multi-agent systems

Open Access Article

1 - A Multi-objective Multi-agent Optimization Algorithm for the Community Detection Problem
Amirhossein Hosseinian Vahid Baradaran

10.7508/jist.2018.03.006

This paper addresses the community detection problem as one of the significant problems in the field of social network analysis. The goal of the community detection problem is to find sub-graphs of a network where they have high density of within-group connections, whil More

This paper addresses the community detection problem as one of the significant problems in the field of social network analysis. The goal of the community detection problem is to find sub-graphs of a network where they have high density of within-group connections, while they have a lower density of between-group connections. Due to high practical usage of community detection in scientific fields, many researchers developed different algorithms to meet various scientific requirements. However, single-objective optimization algorithms may fail to detect high quality communities of complex networks. In this paper, a novel multi-objective Multi-agent Optimization Algorithm, named the MAOA is proposed to detect communities of complex networks. The MAOA aims to optimize modularity and community score as objective functions, simultaneously. In the proposed algorithm, each feasible solution is considered as an agent and the MAOA organizes agents in multiple groups. The MAOA uses new search operators based on social, autonomous and self-learning behaviors of agents. Moreover, the MAOA uses the weighted sum method (WSM) in finding the global best agent and leader agent of each group. The Pareto solutions obtained by the MAOA is evaluated in terms of several performance measures. The results of the proposed method are compared with the outputs of three meta-heuristics. Experiments results based on five real-world networks show that the MAOA is more efficient in finding better communities than other methods. Manuscript profile

Open Access Article

2 - Cooperation in Multi-Agent Systems Using Learning Automata
M. R. »hojasteh M. R. Meybodi

Agents are software entities that act continuously and autonomously in a special environment. It is very essential for the agents to have the ability to learn how to act in the special environment for which they are designed to act in, to show reflexes to their environm More

Agents are software entities that act continuously and autonomously in a special environment. It is very essential for the agents to have the ability to learn how to act in the special environment for which they are designed to act in, to show reflexes to their environment actions, to choose their way and pursue it autonomously, and to be able to adapt and learn. In multi-agent systems, many intelligent agents that can interact with each other, cooperate to achieve a set of goals. Because of the inherent complexity that exists in dynamic and changeable multi-agent environments, there is always a need to machine learning in such environments. As a model for learning, learning automata act in a stochastic environment and are able to update their action probabilities considering the inputs from their environment, so optimizing their functionality as a result. Learning automata are abstract models that can perform some numbers of actions. Each selected action is evaluated by a stochastic environment and a response is given back to the automata. Learning automata use this response to choose its next action. In this paper, the goal is to investigate and evaluate the application of learning automata to cooperation in multi-agent systems, using soccer server simulation as a test-bed. Because of the large state space of a complex multi-agent domains, it is vital to have a method for environmental states’ generalization. An appropriate selection of such a method can have a great role in determining agent states and actions. In this paper we have also introduced and designed a new technique called “The best corner in state square” for generalizing the vast number of states in the environment to a few number of states by building a virtual grid in agent’s domain environment. The efficiency of this technique in a cooperative multi-agent domain is investigated Manuscript profile

Open Access Article

3 - A Model Based on Entropy and Learning Automata for Solving Stochastic Games
B. Masoumi M. R. Meybodi

Stochastic games, as the generalization of Markov decision processes to the multi agent case, have long been used for modeling multi-agent system and are used as a suitable framework for Multi Agent Reinforcement Learning. Learning Automata (LA) were recently shown to b More

Stochastic games, as the generalization of Markov decision processes to the multi agent case, have long been used for modeling multi-agent system and are used as a suitable framework for Multi Agent Reinforcement Learning. Learning Automata (LA) were recently shown to be valuable tools for designing Multi-Agent Reinforcement Learning algorithms. In this paper a model based on learning automata and the concept of entropy for finding optimal policies in stochastic games is proposed. In the proposed model, for each state in the environment of the game and for each agent an S-model variable structure learning automaton is placed that tries to learn the optimal action probabilities in those states. The number of its adjacent states determines the number of actions of each learning automaton in each state and every joint action corresponds to a transition to an adjacent state. Entropy of the probability vector for the learning automaton of the next state is used to help learning process and improve the learning performance and is used a quantitative problem independent measurement for learning progress. We have also implemented a new version of the proposed algorithm that balances exploration with exploitation yielding improved performance. The experimental results show that the proposed algorithm has better learning performance than the other learning algorithms in terms of cost and the speed of reaching the optimal policy. Manuscript profile

Open Access Article

4 - A Goal-Based Approach for the Holonification of Holonic Multi-Agent Systems
Ahmad Esmaeili N. Mozayani M. R. Jahed Motlagh

Holonic structures are a hierarchical formation of holons that are developed and used for the purpose of restricting interaction domains, reducing uncertainty, or forming the high level goals of multi-agent systems, in such a way that the system benefits a high degree o More

Holonic structures are a hierarchical formation of holons that are developed and used for the purpose of restricting interaction domains, reducing uncertainty, or forming the high level goals of multi-agent systems, in such a way that the system benefits a high degree of flexibility and dynamism in response to environmental changes. Although the holonic multi-agent systems are extensively used in modeling and solving complex problems, most of its prerequisites, like forming the body holons and dynamically controlling its structure, use very simple application-specific models. This is due to the immaturity of the research literatures in this field. In this article, an endeavor is made to propose a goal-based approach for the formation of holonic structures, using the concepts in social science and organizational theory. The use of concepts like role, skill, and goal structures, makes the proposed method possible to be used in wide range of applications. In order to demonstrate the capabilities of the method and also the way it can be applied in real world problems, a test bed based on the application of wireless sensor networks in object tracking is designed and presented. In this application, the sensors, which are distributed in the environment as simple agents, using holonic structures, are responsible for the track of any alien objects that enter and move in the environment. According to the empirical results of the simulations, the proposed holonic approach has provided successful performance in terms of tracking quality and energy consumption of the sensors. Manuscript profile

Open Access Article

5 - An Intelligent Overload Controller Using in Next Generation Networks
مهدی خزائی

SIP is considered as a signaling protocol for IP multimedia subsystem (IMS) and IMS is introduced as the next generation networking platform. Unlike positive features such as text-based, IP-based, data-independent, support mobility and end-to-end, SIP lacks a proper ove More

SIP is considered as a signaling protocol for IP multimedia subsystem (IMS) and IMS is introduced as the next generation networking platform. Unlike positive features such as text-based, IP-based, data-independent, support mobility and end-to-end, SIP lacks a proper overload control mechanism. Hence, this challenge will cause the widespread users of next generation networks to loss quality of service. IMS is a complex network consisting of subsystems, interacting with each other. As a result, multi-agent systems can be a useful tool to solve the IMS overload. Therefore, each IMS server is considered as an intelligent agent with learning and negotiation ability with other agents while maintaining autonomy therefore, the overload is eliminated by communication and knowledge transferred between agents. In this paper, multi-agent system and their properties presents a hop-by-hop elimination-based method which simulation results show performance improvement compared to known methods. Manuscript profile

Open Access Article

6 - Fixed-Time Consensus of Fractional-Order Single Integrator Multi-Agent Systems
Hossein Zamani وحيد جوهري مجد Khosro Khandani

The problem of consensus in fractional order single-integrator multi-agent systems has been studied in this paper. The effect of memory is considered using the Riemann-Liouville fractional derivative in the dynamics of the agents. In order to achieve convergence among t More

The problem of consensus in fractional order single-integrator multi-agent systems has been studied in this paper. The effect of memory is considered using the Riemann-Liouville fractional derivative in the dynamics of the agents. In order to achieve convergence among the agents, a fractional order control protocol based on the error signal between neighboring agents is proposed. Using Lyapunov's stability theorem, a Lyapunov function is introduced that shows that the agents converge over a specified settling time and the upper bound of the settling time is obtained. The merit of the proposed bound for the settling time is that it is independent of the initial conditions. Finally, some simulations are provided to confirm the introduced method. Manuscript profile

Open Access Article

7 - Design of a Secondary Controller Based on Distributed Cooperative Control of Distributed Generators (DGs) with Multi-Agent Systems Approach Considering DoS Cyber Attacks
Abdollah Mirzabeigi Ali Kazemy Mehdi Ramezani Seyed Mohammad Azimi

Today, in many control methods, neighboring system information is used for better control and synchronization between different units, and therefore, in the access and transmission of information through communication links, problems such as disruption, uncertainty, noi More

Today, in many control methods, neighboring system information is used for better control and synchronization between different units, and therefore, in the access and transmission of information through communication links, problems such as disruption, uncertainty, noise, delay, and cyber-attacks occur. In this paper, the effect of the Denial of Service (DoS) cyber-attack on the microgrid in island mode is investigated and a cooperative distributed hierarchical controller is designed with the presence of this cyber-attack. Distributed Generations (DGs) have been analyzed with the help of multi-agent systems and the communication network between them using graph theory. The effects of the DoS cyber-attack on the model of DGs are mathematically formulated and in proving the stability and synchronization of frequency and voltage, the suitable Lyapunov function is presented and the stability analysis of DGs against these cyber-attacks is performed and the stability and synchronization conditions of DGs are proved. To confirm the proposed theoretical issues, a case study model is simulated despite the DoS attack on the communicative links in Matlab Simulink, and the results show the performance of the designed controller in different conditions. Manuscript profile

Open Access Article

8 - Stabilizing and Synchronizing the Islanded Microgrid with the Presence of Sensor and Actuator Fault and Cyber-Attack with Secondary Controller Design
Abdollah Mirzabeigi Ali Kazemy Mehdi Ramezani Seyed Mohammad Azimi

In many microgrid control methods, the output information of sensors and actuators of neighbouring distributed generators (DGs) is used to stabilize and synchronize voltage and frequency. Many problems such as disturbances, uncertainty, unmodeled dynamics, cyber-attacks More

In many microgrid control methods, the output information of sensors and actuators of neighbouring distributed generators (DGs) is used to stabilize and synchronize voltage and frequency. Many problems such as disturbances, uncertainty, unmodeled dynamics, cyber-attacks, noise, time delay, and measurement errors cause invalid data problems and errors in the system. Better microgrid control depends on the quality of data measured or sent from the output of sensors and actuators. In this paper, according to the advantages of the Cooperative distributed hierarchical control, it is used for control and synchronization in the islanded microgrid with the presence of sensor and actuator error. To synchronize DGs with multi-agent systems and communication channels, it is modeled with graph theory. To stabilize and synchronize, sensor and actuator error in the DG model is mathematically formulated. In the proof of stability and synchronization, the appropriate Lyapunov candidate is presented and the conditions of stability and synchronization are proved. Finally, to show the effectiveness of the designed controller in solving communication channel problems and verifying the presented theory, a case study is simulated in the MATLAB/Simulink software environment with the presence of error and cyber-attack of sensors and actuators. Manuscript profile

Open Access Article

9 - Analysis of the Effects of Different Cyber Attacks on the Secondary Controller in Island Microgrids
Abdollah Mirzabeigi ali kalantarnia

With the advancement of science, in many control methods, the neighbor system is used to better control and synchronize between different information of microgrids. There are problems in accessing and transmitting information through communication links. In this article More

With the advancement of science, in many control methods, the neighbor system is used to better control and synchronize between different information of microgrids. There are problems in accessing and transmitting information through communication links. In this article, vulnerability and acceptance of secondary control methods are distributed. Also, denial-of-service (DoS) cyber-attacks, sensors and actuators, and hijacking on the island microgrid have been investigated. In addition to stability, synchronization is also analyzed in this article. Multi-agent systems have been used for synchronization. Cyber-attacks are mathematically formulated in the controller. A suitable controller is designed to eliminate the attacks. In the stability and synchronization of frequency and voltage, the Lyapunov function is presented and simultaneous analysis of stability and synchronization has been done with practical proofs. The resilience factor has been calculated for different attacks. It is shown that the system is resilient against cyber-attacks. A case study has been simulated in MATLAB/Simulink to approve the theoretical issues. Manuscript profile

Open Access Article

10 - Design of Distributed Consensus Controller for Leader-Follower Singular Multi-Agent Systems in the Presence of Sensor Fault
Saeid Poormirzaee Hamidreza Ahmadzadeh masoud Shafiee

In this paper, the problem of sensor fault estimation and designing of a distributed fault-tolerant controller is investigated to guarantee the leader-follower consensus for homogeneous singular multi-agent systems for the first time. First, a novel augmented model for More

In this paper, the problem of sensor fault estimation and designing of a distributed fault-tolerant controller is investigated to guarantee the leader-follower consensus for homogeneous singular multi-agent systems for the first time. First, a novel augmented model for the system is proposed. It is shown that the proposed model is regular and impulse-free unlike some similar research works. Based on this model, the state and sensor fault of the system are simultaneously estimated by designing a distributed singular observer. The proposed observer also has the ability to estimate time-varying sensor fault. Then, a distributed controller is designed to guarantee the leader-follower consensus using estimation of state and sensor fault. The sufficeient conditions to ensure the stability of the observer dynamic and consensus dynamic are drived in terms of linear matrix inequalities (LMIs). The gains of observer and controller are computed by solving these conditions with MATLAB software. Finally, the validation and efficiency of the proposed control system for the leader-follower consensus of singular multi-agent systems exposed to sensor faults is illustrated by computer simulations. The simulation results show that the propsed control strategy deeling to the sensor falut in the singular multi-agent systems is effective. Manuscript profile

List of Articles Multi-agent systems

Rimag

Links

Related Centers

Technical Support

Official pages