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ABSTRACT: Sensor localization is a fundamental and crucial issue for wireless sensor networks operation and management. Accurate self-localization capability is highly desirable in wireless sensor network. A fundamental problem in distance-based sensor network localization is whether a given sensor network is uniquely localizable or not. Flip ambiguity is a main problem that can make the sensor network not uniquely localized. It causes large errors in the location estimates. This paper proposes a method in which the localization is done through two steps. During the first step, tabu search (TS) is used to obtain an accurate estimation of the nodes' location. During the second step, simulated annealing algorithm (SAA) is used to refine the location estimates of those nodes that are likely to have flip ambiguity problem. The simulation results confirm that the proposed algorithm has better performance than that of the existing algorithms.
Computer and Automation Engineering (ICCAE), 2010 The 2nd International Conference on; 03/2010
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ABSTRACT: As processing power becomes cheaper and more available by using cluster of computers, the needs for parallel algorithms, which can harness these computing potentials, are increasing. Automatic database normalization is an application of parallel algorithms. Normalization is the most exercised technique for the analysis of relational databases. It aims at creating a set of relational tables with minimum data redundancy that preserve consistency and facilitate correct insertion, deletion, and modification. While existing sequential algorithms are usually much time consuming, especially the process of transforming relations into 3NF, in this paper, we have proposed parallel algorithms for automatic database normalization. The proposed algorithms have been examined with MPI and its implementation results on EDM showed that parallel approach reduces the time, efficiently. Exploiting p processors has reduced the time of Automatic Database Normalization to (n<sup>2</sup> .m)/p + c in which c is the communication overhead between the processors, m is the number of simple keys, and n is the number of determinant keys.
Computer and Automation Engineering (ICCAE), 2010 The 2nd International Conference on; 03/2010
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ABSTRACT: The power of grid technology in aggregating autonomous resources owned by several organizations into a single virtual system has made it popular in compute-intensive and data-intensive applications. Complex and dynamic nature of grid makes failure of users' jobs fairly probable. Furthermore, traditional methods for job failure recovery have proven costly and thus a need to shift toward proactive and predictive management strategies is necessary in such systems. In this paper, an innovative effort is made to predict the futurity of jobs submitted to a production grid environment (AuverGrid). By analyzing grid workload traces and extracting patterns describing common failure characteristics, the success or failure status of jobs during 6 months of AuverGrid activity was predicted with around 96% accuracy. The quality of services on grid can be improved by integrating the result of this work into management services like scheduling and monitoring.
Computer Conference, 2009. CSICC 2009. 14th International CSI; 11/2009
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ABSTRACT: Multiprocessor scheduling belongs to a special category of NP-complete computational problems. The purpose of scheduling is to scatter tasks among the processors in such a way that the precedence constraints between tasks are kept, and the total execution time is minimized. Cellular automata (CA) can be used for multiprocessor scheduling, but one of the difficulties in using CA is the exponentially increasing number of rules with increasing number of processor and neighborhood radius. Here, we propose a combined use of ant colony and evolutionary meta-heuristics to search the rule's feasible space in order to find optimal rule base. Also we introduce a two dimensional cellular automata structure based on the important task attributes in the precedence task graph. The proposed scheduler that uses evolving cellular automata based on ant colony can find optimal response time for some of well known precedence task graph in the multiprocessor scheduling area.
Computer Conference, 2009. CSICC 2009. 14th International CSI; 11/2009
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ABSTRACT: Vehicular travel which demands on the concurrent operations and parallel activities is increasing throughout the world. In this paper to control urban traffic, we study the optimization of traffic light controller in a city and present a fuzzy algorithm based on cellular automata. In existent system factors like priority of streets of intersection and width/length of streets are assumed equal. However, in real situations parameters like time during the day, density of vehicles of street and number of shopping centers have determinant effects on amount of traffic of streets. To overcome such limitations we propose a three leveled fuzzy system. At first level priority of street is computed based on fuzzy rules. At second level real velocity of vehicles is calculated. We use CA for simulating vehicles' density transmission. At third level by regarding priority of street and amount of density, decision for changing status of traffic light is done.
Computer and Information Technology, 2008. ICCIT 2008. 11th International Conference on; 01/2009
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ABSTRACT: Computational structure of cellular automata has attracted researchers and vastly been used in various fields of science. They are especially suitable for modeling natural systems that can be described as massive collections of simple objects interacting locally with each other, such as motion detection in image processing. On the other hand, extraction of moving objects from an image sequence is a fundamental problem in dynamic image analysis. Nowadays background modeling and subtraction algorithms are commonly used in real-time urban traffic applications for detecting and tracking vehicles and monitoring streets. In this paper by the use of cellular automata, a novel fuzzy approach for background subtraction with a particular interest to the problem of vehicle detection is presented. Our experimental results demonstrate that fuzzy-cellular system is much more efficient, robust and accurate than classical approaches.
Signal Processing, 2008. ICSP 2008. 9th International Conference on; 11/2008
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ABSTRACT: Wireless Sensor Networks (WSN) have been noticed and researched nowadays. These new type of networks have unique characteristics. WSNs have different limitations such as computational power, storage capacity, energy source and etc. The main constraint of wireless sensor networks is energy. The energy source of sensor nodes is limited and not rechargeable. Therefore, optimizing consumption of energy is essential for WSNs protocols. Hypercube topology is very popular in distributed environments. In last few years, many different topology specific routing algorithms have been designed for wireless sensor networks, but to the best of our knowledge, none of them consider hypercube as their topology. In this paper, different routing algorithms are proposed for WSN with hypercube topology. The performance of all proposed routing algorithms is evaluated, and the best algorithm which can provide more fairness is introduced. Simulation results which are represented in last section of this paper are the base of our conclusions. The main goal of this paper is to find a fair energy aware routing algorithm for wireless sensor network connected as hypercube.
Telecommunications, 2008. IST 2008. International Symposium on; 09/2008
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ABSTRACT: Scheduling algorithms play an important role in design of real-time systems. Due to high processing power and low price of multiprocessors, real-time scheduling in such systems is more interesting; however, more complicated. Earliest deadline first (EDF) and least laxity first (LLF) are two well-known and extensively applied dynamic scheduling algorithms on which many researches have already been done. However, to the best of our knowledge, the efficiency of aforementioned algorithms has not been compared under similar conditions. Perhaps the main reason is that LLF algorithm is fully dynamic and impractical to implement. In this research, we have used a job-level dynamic and practical version of LLF which is called modified least laxity first (MLLF) algorithm instead of the traditional LLF and have compared its performance with EDF algorithm from many different aspects. The success ratio has been chosen as the key factor for evaluation of the algorithms
TENCON 2006. 2006 IEEE Region 10 Conference; 12/2006
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ABSTRACT: A computational grid is a widespread computing environment which provides huge computational power for large-scale distributed applications. One of the most important issues in such an environment is resource management. Load balancing which is a part of resource manager, has a considerable effect on resources' performance. There are several factors which affect the stability of the load balancing in the grid. Among these factors, accurate criterion for estimating the workload, considering the workload transmission cost, validity of the information about other nodes and the overhead imposed by the method are more effective. In this paper we propose a novel method for load balancing which tries to satisfy these factors. The proposed method is implemented on an agent-based resource management system, called ARMS. There are several simulations which indicate that the proposed method outperforms than similar methods.
Computing & Informatics, 2006. ICOCI '06. International Conference on; 07/2006
