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Liu W.,Huazhong University of Science and Technology | Liu W.,Hubei University of Economics | Tao Q.,Hubei University of Economics | Zhang R.,Applied Technology Internet | And 7 more authors.
IEEE Sensors Journal

Skeleton has been successfully incorporated in the design of high-performance protocol in sensor networks. As there exists a tradeoff between skeleton simplicity and reconstruction error, it is important to quantitatively judge the skeleton and refine it properly. While some studies on skeleton extraction and refinement have been proposed, there still lacks deep understanding of quantitative evaluation and skeleton pruning. In this paper, we consider both the simplicity and reconstruction ability of skeleton, and present ESP, an evaluation-based skeleton pruning algorithm. By analyzing the skeleton properties, we first present the adjusted coverage index of skeleton to measure its goodness, and then provide a novel approach for skeleton pruning. We also analyze that the adjusted coverage index is closely related to the performance of skeleton-based applications, and show by simulations that the ESP can correctly judge the skeleton's goodness and yield a refined skeleton. © 2001-2012 IEEE. Source

Ming L.,Wuhan University of Technology | Liu J.X.,Hubei Key Laboratory of Inland Shipping Technology | Yang S.,Hubei Communications Technical College
Advanced Materials Research

There are many factors affecting vessel's stopping distance and crash stopping distance, and it is very complicated to calculate them accurately. At present there are several calculation methods about them, but all these methods have large error. Based on the research of the existing calculation methods, this paper simplifies vessel resistance and calculates vessel's stopping distance and crash stopping distance accurately by means of physical and mathematical methods. © (2013) Trans Tech Publications, Switzerland. Source

Liu K.,Wuhan University of Technology | Liu K.,Hubei Key Laboratory of Inland Shipping Technology | Zhuang Y.,Wuhan University of Technology | Wang Z.,Wuhan University | Ma J.,Wuhan University of Technology
International Journal of Distributed Sensor Networks

Reliable event detection is one of the most important objectives in wireless sensor networks (WSNs), especially in the presence of faulty nodes. Existing fault-tolerant event detection approaches usually take the probability of faulty nodes into account and fusion techniques to weaken the influence of faulty readings are usually developed. Through extensive experiments, we discover a phenomenon that event detection accuracy degrades quickly when the faulty sensors ratio reaches a critical value. This problem has not drawn enough attention and a solution to the problem is our concern. In this paper, a spatiotemporal correlation based fault-tolerant event detection scheme (STFTED) is proposed, which leverages a two-stage decision fusion and spatiotemporal correlation to improve the event detection quality. In the low-level local stage, a location-based weighted voting scheme (LWVS) is developed to make decision fusion locally on each sensor node, which is based on neighboring nodes and the geographical distributions of two decision quorums. In the high-level global stage, a Bayesian fusion algorithm is adopted to reach a consensus among individual detection decisions made by sensor nodes. Simulation results demonstrate that the proposed approach is highly effective and a better quality of event detection can be obtained compared with the optimal threshold decision schemes (OTDS). © 2015 Kezhong Liu et al. Source

Ma Y.,Wuhan University of Technology | Ma Y.,Hubei Key Laboratory of Inland Shipping Technology | Ma Y.,Huazhong University of Science and Technology | Wang H.,Huazhong University of Science and Technology | And 2 more authors.
Information Sciences

This work investigates the conflict-free path planning problems for efficient guidance of multiple mobile robots under the dynamic double-warehouse environment, a challenging problem that appears recurrently in a wide range of applications such as the service robots moving in a multistory building. United with two symmetrical transfer elevators, double-warehouse consists of two parallel warehouses. Within each warehouse, the polynomial based paths are subject to constraints such as motion boundaries, kinematics constraints, obstacle-avoidance, limited resource of elevators and smoothness. We formulate the shortest path planning problems as one time-varying nonlinear programming problem (TNLPP) while restricted to the above constraints, and apply the multi-phase strategy to reduce their difficulty. We present the new variant algorithms of PSO named constriction factor and random perturb PSO (Con-Per-PSO) and the simulating annealing PSO (SA-PSO) to achieve the solution. Numerical simulations verify that, our approach can fulfill multiple mobile robots path planning problems under double-warehouse successfully. © 2014 Elsevier Inc. All rights reserved. Source

Wu B.,Wuhan University of Technology | Wu B.,Hubei Key Laboratory of Inland Shipping Technology | Wen Y.,Wuhan University of Technology | Wen Y.,Hubei Key Laboratory of Inland Shipping Technology | And 4 more authors.
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering)

Because of small size, fast speed, good invisibility and high intelligence, the Unmanned Surface Vessel (USV) is widely used in the world. Along with the continuous improvement of its application value, the USV has increasingly become the focus of the domestic and foreign research. As one of the core technologies for the USV, collision avoidance technology is an important premise to ensure ship navigation safety and to perform normal tasks. In this paper, according to the collision avoidance problem of the USV, the main research achievements at home and abroad is expounded and some problems of USV collision avoidance methods are summarized from the view of USV global path planning and local collision avoidance. In addition, the future research directions are discussed. © 2016, Editorial Department of Journal of Wuhan University of Technology. All right reserved. Source

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