The wide spread of the 802.11-based wireless technology brings about a good opportunity for the indoor positioning system. In this paper, we present a new 802.11-based indoor positioning method using support vector regression (SVR), which consists of offline training stage and online location stage. The model that describes the relations between the position and the received signal strength (RSS) of the mobile device is established at the offline training stage by SVR, and at the online location stage the exact position is determined by this model. Due to the complex indoor environment, RSS is vulnerable and changeable. To address this issue, data filtering rules obtained through statistical analysis are applied at offline training stage to improve the quality of training samples and thus improve the quality of prediction model. At the online location stage,k-times continuous measurement is utilized to obtain the high quality RSS input, which guarantees the consistency with the training samples and improves the position accuracy of mobile devices. Performance evaluation shows that the proposed method has a higher positioning accuracy compared with the probability and neutral network method, and the demand for the storage capacity and computing power is also low at the same time.

No abstract

Tumor clustering is one of the important techniques for tumor discovery from cancer gene expression profiles, which is useful for the diagnosis and treatment of cancer. While different algorithms have been proposed for tumor clustering, few make use of the expert's knowledge to better the performance of tumor discovery. In this paper, we first view the expert's knowledge as constraints in the process of clustering, and propose a feature selection based semi-supervised cluster ensemble framework (FS-SSCE) for tumor clustering from bio-molecular data. Compared with traditional tumor clustering approaches, the proposed framework FS-SSCE is featured by two properties: (1) The adoption of feature selection techniques to dispel the effect of noisy genes. (2) The employment of the binate constraint based K-means algorithm to take into account the effect of experts' knowledge. Then, a double selection based semi-supervised cluster ensemble framework (DS-SSCE) which not only applies the feature selection technique to perform gene selection on the gene dimension, but also selects an optimal subset of representative clustering solutions in the ensemble and improve the performance of tumor clustering using the normalized cut algorithm. DS-SSCE also introduces a confidence factor into the process of constructing the consensus matrix by considering the prior knowledge of the data set. Finally, we design a modified double selection based semi-supervised cluster ensemble framework (MDS-SSCE) which adopts multiple clustering solution selection strategies and an aggregated solution selection function to choose an optimal subset of clustering solutions. The results in the experiments on cancer gene expression profiles show that (i) FS-SSCE, DS-SSCE and MDS-SSCE are suitable for performing tumor clustering from bio-molecular data. (ii) MDS-SSCE outperforms a number of state-of-the-art tumor clustering approaches on most of the data sets.

No abstract

Accessing data in mobile ad hoc networks is a challenging problem, which is caused by frequent network partitions due to node mobility and due to the impairments of wireless communications. The partitioning pattern is studied by examining the statistics of network partitions for a number of mobility models. Then the relation between the network partitioning pattern and the effectiveness of the data replication scheme is established. Based on these results, a novel replication scheme, RHPMAN (replication in highly partitioned mobile ad hoc network), taking into account the fact that the network is often partitioned in smaller portions, enjoying only intermittent connectivity thanks to mobile nodes traveling across partition, is proposed. In RHPMAN, data items are replicated to the nodes with rather stable neighboring topology and with enough resources. A semiprobabilistic data disseminating protocol is employed to distribute the replicas and propagate the updates, which can identify the potential mobile nodes traveling across partitions to maximize data delivery. To maintain replica consistency, a weak consistency model is utilized to ensure that all updates eventually propagate to all replicas in a finite delay. Simulation results demonstrate that RHPMAN can achieve high data availability with low overhead.