2882279
A topological approach for segmenting human body shape
Segmentation of a 3D human body, is a very challenging problem in applications exploiting human scan data. To tackle this problem, the paper proposes a topological approach based on the discrete Reeb graph (DRG) which is an extension of the classical Reeb graph to handle unorganized clouds of 3D points. The essence of the approach concerns detecting critical nodes in the DRG, thereby permitting the extraction of branches that represent parts of the body. Because the human body shape representation is built upon global topological features that are preserved so long as the whole structure of the human body does not change, our approach is quite robust against noise, holes, irregular sampling, frame change and posture variation. Experimental results performed on real scan data demonstrate the validity of our method.
10029595
A discrete Reeb graph approach for the segmentation of human body scans
Segmentation of 3D human body (HB) scan is a very challenging problem in applications exploiting human scan data. To tackle this problem, we propose a topological approach based on discrete Reeb graph (DRG) which is an extension of the classical Reeb graph to unorganized cloud of 3D points. The essence of the approach is detecting critical nodes in the DRG thus permitting the extraction of branches that represent the body parts. Because the human body shape representation is built upon global topological features that are preserved so long as the whole structure of the human body does not change, our approach is quite robust against noise, holes, irregular sampling, moderate reference change and posture variation. Experimental results performed on real scan data demonstrate the validity of our method.
15048202
Protection and guarantee for voice and video traffic in IEEE 802.11e wireless LANs
In order to support multimedia applications such as voice and video over the wireless medium, a contention-based channel access function, called enhanced distributed coordination function (EDCF), is being developed in the emerging standard IEEE 802.11e. In EDCF, differentiated services are provided for different traffic classes. In this paper, we propose a two-level protection and guarantee mechanism for voice and video traffic in IEEE 802.11e wireless LANs. In the first-level protection, the existing voice and video flows are protected from the new and other existing voice and video flows. In the second-level protection, the voice and video flows are protected from the best-effort data traffic. For each protection level, a couple of protection mechanisms are proposed. Extensive simulation results show that the proposed two-level protection and guarantee mechanism is very effective in terms of protecting and guaranteeing existing voice and video flows as well as fully utilizing the channel capacity
1215436
A permutation test motivated by microarray data analysis
We introduce a nonparametric test intended for large-scale simultaneous inference in situations where the utility of distribution-free tests is limited because of their discrete nature. Such situations are frequently dealt with in microarray analysis where the number of tests is much larger than the sample size. The proposed test statistic is based on a certain distance between the distributions from which the samples under study are drawn. In a simulation study, the proposed permutation test is compared with permutation counterparts of the t-test and the Kolmogorov-Smirnov test. The usefulness of the proposed test is discussed in the context of microarray gene expression data and illustrated with an application to real datasets.
9923549
A Survey of Energy-Efficient Scheduling Mechanisms in Sensor Networks
Sensor networks have a wide range of potential, practical and useful applications. However, there are issues that need to be addressed for efficient operation of sensor network systems in real applications. Energy saving is one critical issue for sensor networks since most sensors are equipped with non-rechargeable batteries that have limited lifetime. To extend the lifetime of a sensor network, one common approach is to dynamically schedule sensors' work/sleep cycles (or duty cycles). Moreover, in cluster-based networks, cluster heads are usually selected in a way that minimizes the total energy consumption and they may rotate among the sensors to balance energy consumption. In general, these energy-efficient scheduling mechanisms (also called topology configuration mechanisms) need to satisfy certain application requirements while saving energy. In this paper, we provide a survey on energy-efficient scheduling mechanisms in sensor networks that have different design requirements than those in traditional wireless networks. We classify these mechanisms based on their design assumptions and design objectives. Different mechanisms may make different assumptions about their sensors including detection model, sensing area, transmission range, failure model, time synchronization, and the ability to obtain location and distance information. They may also have different assumptions about network structure and sensor deployment strategy. Furthermore, while all the mechanisms have a common design objective to maximize network lifetime, they may also have different objectives determined by their target applications.
13948208
Design and analysis of location management for 3G cellular networks
Location management is a key issue in personal communication service networks to guarantee the mobile terminals to continuously receive services when moving from one place to another. We study two location management schemes, a dynamic movement-based scheme (DYNAMIC-3G) and a static scheme (STATIC-3G), for 3G cellular networks where home location registers, gateway location registers (GLRs), and visitor location registers form a three-level hierarchical mobility database structure. For both schemes, the cost functions are formulated analytically. We prove that there is an optimal movement threshold that minimizes the total cost function of DYNAMIC-3G and propose a binary search algorithm to find the optimal threshold. Furthermore, we present performance evaluation and comparison of the proposed schemes with the previous schemes in 2G cellular networks where the GLR is not present. Our studies validate the optimality of the DYNAMIC-3G scheme and show that the proposed schemes outperform the previous schemes, especially when the remote-local-cost ratio is high. The comparison results between DYNAMIC-3G and STATIC-3G indicate that DYNAMIC-3G should be adopted when the mobility rate is low, and STATIC-3G should be adopted otherwise. Furthermore, DYNAMIC-3G tends to perform better than STATIC-3G when the paging cost is high or the number of cells in a location area is large.
1889757
Lightweight Deployment-Aware Scheduling for Wireless Sensor Networks
Wireless sensor networks consist of a large number of tiny sensors that have only limited energy supply. One of the major challenges in constructing such networks is to maintain long network lifetime as well as sufficient sensing areas. To achieve this goal, a broadly-used method is to turn off redundant sensors. In this paper, the problem of estimating redundant sensing areas among neighbouring wireless sensors is analysed. We present simple methods to estimate the degree of redundancy without the knowledge of location or directional information. We also provide tight upper and lower bounds on the probability of complete redundancy and on the average partial redundancy. With random sensor deployment, our analysis shows that partial redundancy is more realistic for real applications, as complete redundancy is expensive, requiring up to 11 neighbouring sensors to provide a 90 percent chance of complete redundancy. Based on the analysis, we propose a scalable Lightweight Deployment-Aware Scheduling (LDAS) algorithm, which turns off redundant sensors without using accurate location information. Simulation study demonstrates that the LDAS algorithm can reduce network energy consumption and provide desired QoS requirement effectively.