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A multi-robot exploration approach is suggested in this paper that works on the premise that the topo-metric map of the indoor environment is known a priori. Genetic Algorithms (GAs) are used for spatial partitioning of the topo-metric graph of the environment. Each spatial partition, which represents the sub-graph, is apportioned to a unique robot by using the Hungarian method for task assignment in conjunction with Bully Algorithm for leader election. In the case of robot(s) failure, graph re-partitioning and single item auctions are used for re-assigning the remaining task(s) of the failed robot(s) to other robots. The proposed approach performs better than a recent state-of-the-art strategy that employs Delaunay triangulation and multi-prim algorithm for multi-robot exploration. Empirical results obtained in simulation by varying the number of robots in two different and complex environments prove the efficacy of the proposed approach.

In distributed computing, to select a leader is an essential problem for research discussion. Without a leader, many applications in a distributed system are unable to communicate, take a decision and to achieve a needed goal. To solve this sort of problem leader election algorithm is one of the best approaches. The bully algorithm is one of the safe and simplest methods to select a leader, in which the highest priority identity (ID) number is used to select as a leader if the existing leader has failed. In every distributed leader election algorithm every node has a unique ID which known to every other node in the distributed system. The performance of an algorithm is measured in terms of numbers of messages (communication cost). There is a space to improve this algorithm by reducing the numbers of messages required in election procedures. Therefore this paper seeks to reflect a comparative analysis of bully, modified bully, ring and our proposed bully algorithm. Our proposed algorithm has used O(1) messages complexity for leader election in the best and worst case while uses O(n) messages for to inform all alive nodes in the system that I am a new leader and significantly reduce the number of messages. The results show that our proposed algorithm is a simplest method and outperforms then existing algorithms in terms of time, messages complexity and number of stages.

This paper presents a context-aware Personal Area Network (PAN) coordinator selection algorithm - CAPCoS, for real-time acquisition of physiological data of soldiers in battle-field. PAN coordinator selection procedure in Wireless Body Area Networks (WBANs), must have some WBAN specific attributes and scenario specific attributes. In this work, we consider three criteria such as - successful delivery of data packets at sink, cooperation among different hops during multi-hop routing, and health severity of individual soldiers. CAPCoS uses the concept of absorbing Markov chain in order to quantify the rate of successful delivery of packets or the Absorption Rate (AR) of each hop. The cooperation Index (CI) represents the ratio of data-out to data-in, for each hop. Priority of Health (PH) represents the normalized health severity of each soldier. In order to select the most preferable Local Processing Unit (LPU) as the PAN coordinator among allWBAN-equipped soldiers, we employ the concept of Analytical Hierarchy Processing (AHP), which generates a proper ranking of the LPUs, based on the aforementioned three criteria. We achieve around 50% improvement in both network lifetime and traffic using the proposed algorithm.

In distributed computing, a task is divided into subtasks and each task is processed by one of the computers available in the network. These computers communicate with each other through message passing. Also, it is necessary to achieve synchronization between these multiple nodes. In order to achieve the same and coordination, there is a need of coordinator node also known as leader node. Now, to elect node we have several algorithms proposed by various researchers and over the past years several changes have been take place over these algorithms to optimize the algorithmic complexity (in term of time, number of messages and robustness). In this paper we propose a location and priority based approach to select the coordinator node among diverse nodes present in a distributed environment. Based on our experimental results, the proposed approach reduces the network traffic by reducing number of messages in the network. Furthermore, this approach is justified by comparing it with previously proposed election algorithms with respect to the number of messages passed for election process.

In a distributed system to coordinate various jobs among processes, there is a need of a Leader Node or Coordinating Node. Selection of coordinator node in distributed environment plays an important role in the system performance. In the real world, it is not possible that the coordinator node is always available because of some failure occur sometimes it get crashed, out of service. In literature various approaches have been proposed in order to conduct an election mechanism when coordinator node gets crashed. Although these approaches provide different techniques to conduct elections and also to minimize the number of messages required. But these approaches have some drawbacks such as wastage of network bandwidth In order to overpower these drawbacks we proposed an algorithm for Coordinator selection that is used in the centralized distributed system. This gives a better performance than bully algorithm and the other existing proposed algorithm for coordinator selection. Our algorithm selects a coordinator in O (n) time as well as it handles the failure of nodes in less number of message exchange the message is O (n) message but practically it is very lower than O(n).

The Election paradigm can be used as a building block in many practical problems such as group communication, atomic commit and replicated data management where a protocol coordinator might be useful. Mobile systems are more prone to failures than conventional distributed systems. Solving election in such an environment requires from a set of mobile hosts to choose a mobile host or a fixed host based on the their priority despite failures of both mobile computing and/or fixed hosts. In this paper, we describe a solution to the election problem from mobile computing systems. This solution is based on the Garcia Molina's Bully algorithm.

In a distributed database environment, when the coordinator site (root node or process) is not working, the environment needs to choose or elect a new one in order to perform the transactional tasks. The elected coordinator takes the lead to perform the activities as well and continues the functioning. If the previous (crashed) site is recovered from the failures then again it leads the system by taking the responsibility. In this paper, a recovery instance based on bi-directional ring election algorithm for the crashed coordinator was brought up. The new algorithm for the recovered site quickly brings the state back by sending messages in parallel instances. This work shows that how the algorithm makes the recovered site faster and takes less time to make the system quickly to handle transactions normally.

In a distribution computing system or mobile network, leader election is a very important issue. A leader is responsible of making sure the synchronization between different devices. In addition, a leader would assure the responsibility of dispatching IP, updating routing information and service list. The Bully election algorithm is one of the well-known leader election algorithms. Its drawbacks are message passing cost and complexity. Many modified Bully algorithms have been proposed to reduce the redundancy of the election process and the number of message passing. However, their modifications did not take group consensus into consideration. Thus, they cani¦t handle the problem of having more than one node declare to be the leader. In this paper, we propose a consensus-based leader election algorithm. By analyzing the mathematic analysis and algorithm simulation results, we notice that, when a new leader is elected, the proposed algorithm guarantees a consensus be reached while at the same time reducing the number of message passing.

In centralized algorithm for mutual exclusion, one process is elected as a coordinator. Whenever a process wants to go to critical section, it sends a request message to the coordinator and asks for permission. The election of coordinator is an important problem in distributed systems. After a failure occurs in the system, it is necessary to reelect a new leader as a coordinator. The bully election algorithm is one of the classic methods which is used to determine the process with highest priority number as the coordinator. But this algorithm often needs a lot of message passing to find out which process should be a new coordinator. In this paper we are going to propose an optimized method for the bully algorithm called modified bully algorithm. Our analytical simulation shows that, our algorithm has fewer message passing and is more efficient.

In a distributed system, when the coordinator is not functioning, the system needs to elect a new coordinator to enable the active node to perform useful tasks. In this paper, a bi-directional election algorithm based on ring topology was brought forward after we analyzed a classical distributed election algorithm. The new algorithm could quickly elect the coordinator by sending messages in parallel. Study shows that the new algorithm takes less time to elect a new coordinator to enable the system quickly to operate normally.

Aimed at a synchronized multi-hop cluster-tree network, which is quite suitable for QoS support in WSNs,this paper unveils the ambiguities regarding the use of the cluster-tree topology and proposes scheduling mechanisms approach based on super frame duration scheduling with coordinator grouping. In this approach, time is divided such that beacon frames and the super frame duration of a given coordinator are sent during the inactive period of its neighbor coordinators. The idea is that each coordinator selects the starting time Beacon_Tx_Offset to transmit its beacon frame. The starting time must be different from the starting times of its neighbor coordinators and their parents. This approach requires that a coordinator wakes up both in its active period and in its parent's active period. The feasibility of the proposal is clearly demonstrated through an experimental test bed based on our own implementation of the IEEE 802.15.4/Zigbee protocols.

In this paper a new algorithm based on the centralized algorithm for mutual exclusion in distributed systems is proposed that instead of one coordinator uses two coordinator On separate sites (But every moment One of them as coordinator whole system).In our method, if for any reason main Coordinator crashes, until recovery it, secondary coordinator controls critical section versus Simultaneous accesses of processes and prevents simultaneous accesses to shared resources. Its functionality is like to centralized algorithm; processes send your request for entrance to critical section first to main coordinator and if it has been crashed, send your request to secondary coordinator. Unlike the centralized algorithm in proposed algorithm coordinator is not a point of failure and with crashing coordinator, entire system doesn’t go down. The proposed algorithm against the failure of coordinator is much flexible.

Leader election is an important problem in distributed computing systems. In this problem, when the leader is crashed, other nodes must elect another leader. Garcia-Molina’s Bully Algorithm is a classic solution to cope with this problem. In this paper we introduce a new method based on electing a leader and alternatives. If the leader crash, the alternative takes, care of the leader's responsibilities. Our results revealed that often, after a leader crash, leader alternative elect as a leader and continue to work. increases. We show that our proposed algorithm is more efficient than the Garcia Molina’s one in term of time, message complexity and in the fewer stages.

Multi-cluster system has been a popular platform for HPC (high performance computing) environments. But it is lack of flexibility and usability, especially for the vehicle-bone and mobile parallel computation. To solve the problem, we propose a reconfigurable mechanism for the management of multi-cluster system in this paper. The concept of reconfiguration is that the structure of the multi-cluster system could change dynamically, including addition and quit of clusters. According to this, we analyze the key issues and design the reconfigurable mechanism by two aspects, including the architecture and the cases of the mechanism. Then some policies are proposed to achieve it, which are accomplished by aggregation algorithm and optimized Bully algorithm. This mechanism increases the flexibility of HPC environments.

This paper reports a scheme that selects a process as a coordinator from a set of n processes of a distributed system. The scheme demands only O(n) messages in worst case to select a leader. In the proposed scheme, each process maintains a partial view of the global state of the system, and that view enables the system to select a coordinator in an efficient way.

A wireless sensor network can be divided into several clusters. Each cluster has a number of sensors nodes and one of the nodes is elected as the coordinator. The coordinator is responsible for not only the general mission but also collecting the sensed data of other nodes and routing to the sink. Accordingly, the energy-consumption is higher than other nodes. Therefore, the coordinator selection methods will affect the life-time of a network. Besides, the conventional coordinator selection method cannot be available to different requests of sensor networks. In this study, we divided the missions into two types. One is that a mission can be performed by most of the sensor nodes. The other is that a mission can be performed by just few of the sensor nodes. Accordingly, we give different selection methods to suitable the requests. Simulation results demonstrate our study can enlarge the life time for different requests of the sensor networks.

This Days networks are growing rapidly and managing this networks becomes harder too. A similar case can be seen in the leader election area. leader election is the process of designating a single process as the organizer of some task distributed among several nodes. First we discussed about primary leader election algorithms (bully and ring) and their improvements then considering some assumptions we have proposed two new schemes and discussed about some aspects of them.We proposed Sun(n) and Divided(n) algorithms that can be seen as a tradeoff between bully and ring algorithms. Note that if proposed algorithms didn't work then the original algorithm will be done. That is this algorisms are optionally and just try to reduce latency in the vast networks. In general our paper provide a srvey and a good vision af designing leader election algorithms.

In this paper, we propose a distributed algorithm to elect the top K leaders among the nodes in a wireless ad hoc network. Leader election is a fundamental distributed coordination problem arising from many applications, e.g. token regeneration, directory service. However, there is no deterministic algorithm proposed for electing k leaders. In our algorithm, election is based on the weight values of the nodes, which can represent any performance related attribute such as the node's battery power, computational capabilities etc. To achieve message efficiency, coordinator nodes are first selected locally and then the coordinator nodes collect the weight information of other nodes using a diffusing computation approach. The coordinator nodes collaborate with each other to further reduce the message cost. Node failures are also considered in our design. The simulation results show that, compared with a naive solution, our proposed algorithm can elect top K leaders with much less message cost.

Central controlling processor is applied in many scientific fields such as computer network, centralized mutual exclusion algorithm, centralized control IPC, Berkeley algorithm, etc. Central controlling processor in distributed systems is a very important problem, and this problem must be solved by suitable algorithms. The main goal of central controlling processor is synchronizing the process at optimal using of the resources. In this paper we call the central controlling processor as a leader many different algorithms have been presented for leader election. The most important leader election algorithms are the bully and ring algorithms. Ring election algorithm is one of the classic method which is used to virtual ring and determine the process with highest number as the coordinator, and one of the most important leader election algorithm is the bully algorithm. In this paper we describe novel approaches with fault tolerant method to improve the bully and ring algorithms. Our simulation shows that our algorithm is more efficient rather than the ring algorithm in number of message passing. By doing this, performance and behavior will be improved and message passing will be reduced

Many distributed systems have a coordinator and a number of grouppsilas members that coordinator is responsible for coordinating them. Obviously, in such system reliable multicasting is important but offering reliable multicasting services in large groups has many problems and is difficult. One way of solving these problems is using hierarchical structures. A problem in hierarchical structure is holding election when coordinator or a local coordinator crashes. Unfortunately existence election algorithms such as bully and ring donpsilat support hierarchical structure. In this paper, we introduce a new election algorithm for hierarchical groups.

Leader election is an important problem in distributed computing. H. Garcia-Molina's (1982) Bully algorithm is a classic solution to leader election in synchronous systems with crash failures. In this paper, we indicate the problems with the Bully algorithm and re-write it to use a failure detector instead of explicit time-outs. We show that this algorithm is more efficient than Garcia-Molina's one in terms of processing time.