Energy-balanced on demand clustering improved leach protocol for wireless sensor networks

In wireless sensor networks（WSNs）,appropriate topology control（TC）could efficiently balance the load among sensor nodes and extend network lifespan.Clustering is an effective topology control technique that could reduce energy consumption and provide scalability to WSNs.However,some clustering algorithms,including the traditional low energy adaptive clustering hierarchy（LEACH）,don＇t consider the residual energy and the communication distance.The energy consumption could dramatically increase in the case of long communication distance and high rate of control message exchange.In this paper we propose an energy-balanced clustering algorithm which considers the communication distance and the residual energy.Moreover the cluster head（CH）reselection is relevant to the current CH residual energy in order to reduce overheads.The simulation results demonstrate that the proposed algorithm prolongs the lifetime of the WSN in comparison to the LEACH and a hybrid clustering approach（HCA）.

CLUSTERING VALIDITY BASED ON THE IMPROVED S_DBW INDEX

For many clustering algorithms,it is very important to determine an appropriate number of clusters,which is called cluster validity problem.In this paper,a new clustering validity assessment index is proposed based on a novel method to select the margin point between two clusters for in-ter-cluster similarity more accurately,and provides an improved scatter function for intra-cluster similarity.Simulation results show the effectiveness of the proposed index on the data sets under consideration regardless of the choice of a clustering algorithm.

CLASSIFYING WESTERN NORTH PACIFIC TROPICAL CYCLONES BY PHYSICAL INDEX SYSTEM

The classification of tropical cyclones(TCs) is significant to obtaining their temporal and spatial variation characteristics in the context of dramatic-changing global climate. A new TCs clustering method by using K-means clustering algorithm with nine physical indexes is proposed in the paper. Each TC is quantified into an 11-dimensional vector concerning trajectory attributes, time attributes and power attributes. Two recurving clusters(cluster A and E)and three straight-moving clusters(cluster B, C and D) are categorized from the TC best-track dataset of the western North Pacific(WNP) over the period of 1949-2013, and TCs' properties have been analyzed and compared in different aspects. The calculation results of coefficient variation(CV) and Nash-Sutcliffe efficiency(NSE) reveal a high level of intra-cluster cohesiveness and inter-cluster divergence, which means that the physical index system could serve as a feasible method of TCs classification. The clusters are then analyzed in terms of trajectory, lifespan, seasonality, trend,intensity and Power Dissipation Index(PDI). The five classified clusters show distinct features in TCs' temporal and spatial development discipline. Moreover, each cluster has its individual motion pattern, variation trend, influence region and impact degree.

An Improved Virtual Machine Placement Algorithm Based on Traffic Bandwidth Optimization in Data Center

The Virtual Machine(VM) placement is a serious problem to limit the improvement of resource utilization of data center. The VM traffic bandwidth demand is a Non zero-sum resource that the global traffic sum is relative with each VM placement position. In this paper, we introduce a new improved traffic constant algorithm in the data center, called Degree and Weighted Maximum Traffic Ratio(DWMTR). The proposal DWMTR algorithm defines a new weighted ratio parameter in this paper. The main body of the parameter is constructed with the ratio, current overall intra-cluster traffic divided by current overall inter-cluster traffic, when a new VM places in the data center. The DWMTR algorithm has the ability to constraint the inter-cluster traffic incensement more strictly than the current VM placement algorithms based on traffic bandwidth allocation. For this algorithm based on the theoretical analysis and simulation, it confirms the proposed DWMTR possesses smaller global interactive traffic cost than the control group algorithms in the appointed VM placement in the three-layer data center model.