Purpose - shortestpath problem has always been a hot topic in the study of graph theory, because of its wide application field, extending from operational research to the disciplines of geography, automatic control, ...
详细信息
Purpose - shortestpath problem has always been a hot topic in the study of graph theory, because of its wide application field, extending from operational research to the disciplines of geography, automatic control, computer science and traffic. According to its concrete application, scholars in the relevant field have presented many algorithms, but most of them are solely improvements based on Dijkstra algorithm. The purpose of this paper is to enrich the kinds of (and improve the efficiency of) the shortest path algorithms. Design/methodology/approach - This paper puts forward an improved calculation method of shortestpath using cellular automata model, which is designed to search the shortestpath from one node to another node. Cellular state set is adjusted with combination of breeding and mature states. Evolution rule is improved to enhance its parallelism. At the same time, recording manner of cellular state turnover is modified to record all information sources. Findings - The result indicates that the improved algorithm is correct and more efficient, in that it could reduce the times of cellular state turnover;meanwhile, it can solve multi-paths problem. Originality/value - In this paper, cellular state set in exiting shortest path algorithm based on cellular automata theory is adjusted;evolution rule is improved;and recording manner of cellular state turnover is modified to record all information sources. All of which make the parallelism of this algorithm enhanced and the multi-paths problem solved.
Virtual colonoscopy detects polyps by navigating along a colon centerline. Complete colon segmentation based on computed tomography (CT) data is a prerequisite to the computation of complete colon centerline. There ar...
详细信息
Virtual colonoscopy detects polyps by navigating along a colon centerline. Complete colon segmentation based on computed tomography (CT) data is a prerequisite to the computation of complete colon centerline. There are two main problems impeding complete segmentation: overdistention/underdistention of colon and the use of oral contrast agents. Overdistention produces loops in the segmented colon, while underdistention may cause the segmented colon collapse into a series of disconnected segments. Use of oral contrast agents, which have high attenuation on CT, may add redundant structures (bones and small bowels) to the segmented colon. A fully automated colon segmentation method is proposed in this paper to address the two problems. We tested the proposed method in 170 cases, including 37 "moderate" and 133 "challenging" cases. Computer-generated centerlines were compared with human-generated centerlines (plotted by three radiologists). The proposed method achieved a 90.56% correct coverage rate with respect to the human-generated centerlines. We also compared the proposed method with two existing colon segmentation methods: Uitert's method and Nappi's method. The results of these two methods were 75.16% and 72.59% correct coverage rates, respectively. Our experimental results indicate that the proposed method could yield more complete colon centerlines than the existing methods.
In this paper, we propose a novel path-preserving trellis-search (PPTS) algorithm and its high-speed VLSI architecture for soft-output multiple-input-multiple-output (MIMO) detection. We represent the search space of ...
详细信息
In this paper, we propose a novel path-preserving trellis-search (PPTS) algorithm and its high-speed VLSI architecture for soft-output multiple-input-multiple-output (MIMO) detection. We represent the search space of the MIMO signal with an unconstrained trellis, where each node in stage of the trellis maps to a possible complex-valued symbol transmitted by antenna. Based on the trellis model, we convert the soft-output MIMO detection problem into a multiple shortestpaths problem subject to the constraint that every trellis node must be covered in this set of paths. The PPTS detector is guaranteed to have soft information for every possible symbol transmitted on every antenna so that the log-likelihood ratio (LLR) for each transmitted data bit can be more accurately formed. Simulation results show that the PPTS algorithm can achieve near-optimal error performance with a low search complexity. The PPTS algorithm is a hardware-friendly data-parallel algorithm because the search operations are evenly distributed among multiple trellis nodes for parallel processing. As a case study, we have designed and synthesized a fully-parallel systolic-array detector and two folded detectors for a 4 x 4 16-QAM system using a 1.08 V TSMC 65-nm CMOS technology. With a 1.18 mm(2) core area, the folded detector can achieve a throughput of 2.1 Gbps. With a 3.19 mm(2) core area, the fully-parallel systolic-array detector can achieve a throughput of 6.4 Gbps.
In this paper, we presented a method for shortestpath computation process using Dijkstra algorithm based on Pairing heap. We compared the methods by the Pairing heap method and Fibonacci heap method. With experiment,...
详细信息
ISBN:
(纸本)9780769548111
In this paper, we presented a method for shortestpath computation process using Dijkstra algorithm based on Pairing heap. We compared the methods by the Pairing heap method and Fibonacci heap method. With experiment, we could see that the method by Pairing heap have more efficiency than by Fibonacci heap.
In this paper, we presented a method for shortestpath computation process using Dijkstra algorithm based on Pairing heap. We compared the methods by the Pairing heap method and Fibonacci heap method. With experim...
详细信息
In this paper, we presented a method for shortestpath computation process using Dijkstra algorithm based on Pairing heap. We compared the methods by the Pairing heap method and Fibonacci heap method. With experiment, we could see that the method by Pairing heap have more efficiency than by Fibonacci heap.
shortestpath Tree Problem has always been a popular problem but with the devise of Dijkstra's algorithm, SPT and many related problems received immense intention of researchers. shortestpath Tree plays an import...
详细信息
ISBN:
(纸本)9783642221903
shortestpath Tree Problem has always been a popular problem but with the devise of Dijkstra's algorithm, SPT and many related problems received immense intention of researchers. shortestpath Tree plays an important role in many applications like robot navigation, games, transportation and communication routing, etc. In many applications like network and vehicle routing, fast and reliable recovery from the failure is desired. Recovery from these failed links need means and/or plan, with least additional healing cost for the prolongation of the process with no or minimum delay. This paper presents an approach to recover from undesirable state of link failure(s) back to the normal state of working. A shortestpath tree is being extracted from the graph with alternate path at each point (junction) keeping the cost as low as possible.
path travel time reliability is an essential measure of the quality of service for transportation systems and an important attribute in travelers' route and departure time scheduling. This paper investigates a fun...
详细信息
path travel time reliability is an essential measure of the quality of service for transportation systems and an important attribute in travelers' route and departure time scheduling. This paper investigates a fundamental problem of finding the most reliable path under different spatial correlation assumptions, where the path travel time variability is represented by its standard deviation. To handle the non-linear and non-additive cost functions introduced by the quadratic forms of the standard deviation term, a Lagrangian substitution approach is adopted to estimate the lower bound of the most reliable path solution through solving a sequence of standard shortestpath problems. A subgradient algorithm is used to iteratively improve the solution quality by reducing the optimality gap. To characterize the link travel time correlation structure associated with the end-to-end trip time reliability measure, this research develops a sampling-based method to dynamically construct a proxy objective function in terms of travel time observations from multiple days. The proposed algorithms are evaluated under a large-scale Bay Area, California network with real-world measurements. (C) 2011 Elsevier Ltd. All rights reserved.
The merits of the routing algorithm will have a direct impact on the performance of a communication network. Traditional satellite routing algorithms are based on shortest path algorithm, the simply considering least ...
详细信息
ISBN:
(纸本)9781424462520
The merits of the routing algorithm will have a direct impact on the performance of a communication network. Traditional satellite routing algorithms are based on shortest path algorithm, the simply considering least delay, the least hop or the best link-bandwidth utilization. For the request of real-time in information network, a routing algorithm BDSR (bandwidth-delay satellite routing) comprehensively considering both delay and bandwidth between satellite-link is proposed in this paper. Moreover, we prove that the routing algorithm is an ideal one that is suitable for LEO satellite network on NS2 simulation platform.
The hazardous materials on highway are becoming a lot of mobile hazardous sources. If the accidents occur, they can produce great influences for people, property and environment. With the development of economic, the ...
详细信息
ISBN:
(纸本)9783037852446
The hazardous materials on highway are becoming a lot of mobile hazardous sources. If the accidents occur, they can produce great influences for people, property and environment. With the development of economic, the transport volume of hazardous material is considerably increasing, and the potential risk of hazardous material for environment and mankind is enlarging. How to select the best transportation route, insure transportation safety and reach destination rapidly is an important problem for decision department. Aim at transportation network of hazardous materials, this paper studied the resultant impedance of each road. Then this paper turned the hazardous material highway transportation route decision-making problem into a single objective shortestpath problem and applies the improved cellular automata model to solve it. Finally, an example confirmed the feasibility of the decision-making method. The decision-making method of hazardous material can help the government supervision and management department choose the best route.
This paper investigates the optimal power routing problem in relay-based cooperative networks, where the relays are arbitrarily positioned. We generalize the standard shortestpath routing algorithm (GSPRA) to find a ...
详细信息
ISBN:
(纸本)9781612842332
This paper investigates the optimal power routing problem in relay-based cooperative networks, where the relays are arbitrarily positioned. We generalize the standard shortestpath routing algorithm (GSPRA) to find a minimum-power route omega(D) from a source to a destination while satisfying a given end-to-end (e2e) outage probability in distributed MIMO multi-hop networks. The task of the proposed approach includes how to group relays an virtual antenna arrays (VAAs) and discover the optimal multi-hop path. Instead of using per hop (or link) constraints, which is assumed by most of the existing routing algorithm, an e2e outage probability constraint is considered for more relevance and freedom in practical systems. By introducing the concept of virtual nodes and virtual links, an efficient power allocation solution for general distributed MIMO multi-hop networks is used to calculate link costs for the shortest path algorithm. The proposed routing approach fully exploits the merits of both cooperative communications and multi-hop transmissions. The significant power savings due to the proposed approach in comparison to existing algorithms is demonstrated by numerical results.
暂无评论