Abstract: To meet the need of extracting cluster boundary from mixed attribute data in the field of data analysis, we propose a cluster boundary detection algorithm for mixed attribute data sets in this research, named CHASM (Cluster Boundary Detection Algorithm based on Shadowed Set). Based on the structure of clusters, the CHASM defines a new objective function according to the data set which is categorized into three collections, i.e. core, exclusion and shadow. Then CHASM updates the centroid information of clusters based on the variance of contribution degree among these collections to the clusters centroids. Finally, in an iterative optimization process,…the CHASM can extract its shadow sets from each cluster to form the boundary of clusters. The experimental results, on both the synthetic data and real data with mixed attributes, numerical attributes and categorical attributes, show that CHASM can effectively detect cluster boundary with higher or similar accuracy to its rival methods. Furthermore, the CHASM can eliminate noise effectively.
Show more
Keywords: Mixed attributes, high-dimensional data, cluster boundary, shadowed set
Abstract: It is difficult to recharge or replace the batteries in wireless sensor networks. So taking corresponding measures to reduce energy consumption to prolong lifetime without affecting the communication coverage is one of the most important challenges. At present, many researchers use the concept of backbone network to achieve this goal. Nodes which are not in backbone network can go to sleep state for topological simplification and energy conservation. By using the time-based and energy-based topology maintenance, this paper analyzes and compares four backbone-based topology construction protocols, namely A3, A3Cov, EECDS and CDS Rule K. Simulation results show that the time-based-A3…and energy-based-A3 perform better than other protocols in terms of lifetime and communication coverage. Then a hybrid topology control technology based on A3 (hybrid-based-A3) is presented for wireless sensor networks. During the topology construction phase, the importance weight is added into the A3 algorithm. During the topology maintenance phase, we mix time-based and energy-based methods. Based on the “Active Nodes from Sink” and “Communication Coverage” metrics, the performance comparison of time-based-A3, energy-based-A3, and hybrid-based-A3 topology control algorithms are simulated on Java platform. The results show that the hybrid-based-A3 algorithm performances better than time-based-A3 and energy-based-A3.
Show more