Ship weather routing is used to obtain a shortest time path or most economical path considering weather conditionMany approaches have been studied to solve ship-routing problem, and dijkstraalgorithm is quite practic...
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ISBN:
(纸本)9781510828087
Ship weather routing is used to obtain a shortest time path or most economical path considering weather conditionMany approaches have been studied to solve ship-routing problem, and dijkstraalgorithm is quite practical among themA modified dijkstra algorithm using structure matrix and single linked list is applied to establish shortest time route in this passageThe weights are stored by structure matrix instead of adjacency matrix and single linked list is used for less time consumptionThe modifiedalgorithm owns a better computational complexity due to the improved methods, meanwhile, simulations are made to illustrate the result of the modifiedalgorithm.
Path selection is one of the fundamental problems in emergency logistics management. Two mathematical models for path selection in emergency logistics management are presented considering more actual factors in time o...
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Path selection is one of the fundamental problems in emergency logistics management. Two mathematical models for path selection in emergency logistics management are presented considering more actual factors in time of disaster. First a single-objective path selection model is presented taking into account that the travel speed on each arc will be affected by disaster extension. The objective of the model is to minimize total travel time along a path. The travel speed on each arc is modeled as a continuous decrease function with respect to time. A modified dijkstra algorithm is designed to solve the model. Based oil the first model, we further consider the chaos, panic and congestions in time of disaster. A multi-objective path selection model is presented to minimize the total travel time along a path and to minimize the path complexity. The complexity of the path is modeled as the total number of arcs included in the path. An ant colony optimization algorithm is proposed to solve the model. Simulation results show the effectiveness and feasibility of the models and algorithms presented in this paper. (C) 2008 Elsevier Ltd. All rights reserved.
Building fires are one of the most common fire types and tend to cause heavy casualties. During the evacuation, the shortest path makes the escapees leave the accident scene faster. Meanwhile, the safety of escapees i...
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Building fires are one of the most common fire types and tend to cause heavy casualties. During the evacuation, the shortest path makes the escapees leave the accident scene faster. Meanwhile, the safety of escapees in the evacuation process cannot be ignored. Optimal path should both ensure evacuation efficiency and maximize the safety of escapees. A bi-objective path planning model, which considers both path risk and path length, is presented. Path risk is based on five risk factors that are likely to cause casualties in a fire: carbon monoxide (CO), hydrogen cyanide (HCN), temperature, visibility, and crowding. The linear weighted sum method is used to convert the risk-objective model and the length-objective model into a dynamic bi-objective path planning model. The dijkstraalgorithm is modified to solve the model. The modifiedalgorithm outperforms the traditional dijkstraalgorithm in terms of both efficiency and adjustment ability. The simulation analysis of a building fire shows that the bi-objective model and algorithm can plan a combined optimal evacuation path for escapees considering risk and path length, which avoids the area with high risk level and optimizes the evacuation path length.
The problem of dynamic routing in a multifibre time-slotted wavelength routed WDM network is considered. Requests to establish a connection are dynamic and each connection requests an integer multiple of some basic un...
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The problem of dynamic routing in a multifibre time-slotted wavelength routed WDM network is considered. Requests to establish a connection are dynamic and each connection requests an integer multiple of some basic unit. Each wavelength has the capacity of carrying a multiple of these channels, where each channel is represented by a time-slot as in TDM networks. The network is represented as a layered graph model with multiple layers, where each layer represents a specific wavelength. Each link in the layered graph has one or more fibres and an associated cost. The cost of layered graph links could be a function of the loading state of the respective wavelength across the available fibres. algorithms are proposed for fibre selection and for setting link costs, and a modified dijkstra algorithm on the layered graph is used to select a route on the layered graph for a new connection request. The selected route on the layered graph represents the physical path and the selected wavelength. The performance of these algorithms is evaluated for a realistic mesh network topology for various combinations of the number of wavelengths, the number of fibres per link, the number of time-slots per wavelength, and the offered load for both uniform and non-uniform traffic loads. The best performing fibre selection and link cost update methods are identified. The proposed algorithm for routing and wavelength assignment in mesh optical WDM grooming networks outperforms previously proposed work in the literature.
Various traffic network usage formats have arisen along with the popularization of automobiles and the continued service extension of busses, subways, and other forms of public transportation. Due to various character...
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Various traffic network usage formats have arisen along with the popularization of automobiles and the continued service extension of busses, subways, and other forms of public transportation. Due to various characteristics of public transportation networks, unlike general street networks, many issues can affect public transportation, and an optimal course search should be considered. Present research considers plans to improve the overall efficiency of public transportation systems with regard to destination, means, route, and other factors to be selected efficiently in this environment as public transportation usage increases. From this perspective, it suggests the characteristics that a multimodal transit network route search algorithm should have and a corrective algorithm that implements this in an applicable program. Implementation was done in Google android application which provides a simple user interface to find optimal routes in Google Map. The proposed application would enable overall quality-of-service improvement and balanced usage of public transportation, efficient traffic management, and other advantages.
Change propagation is a process in which a change to one part or element of a developed mechanical product tends to induce additional changes to other elements of the product, and the changes can propagate further ite...
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Change propagation is a process in which a change to one part or element of a developed mechanical product tends to induce additional changes to other elements of the product, and the changes can propagate further iteratively. Different change propagation paths yield different change fulfillment costs (development expenditures, lead times, quality losses, etc.). In this study, we seek an optimal change propagation path based on complex theories, and by using this approach the cost of the change can be minimized. In particular, we introduce a modified dijkstra algorithm coupled with a complex network described based on two variables: change probability and change impact. The network depicting the components of a mechanical product and their dependencies is directional while considering both node weights and edge weights. The roles of the components such as change absorbers, carriers, and multipliers are identified. Moreover, the loop change propagation paths and "AND" logical relations between sibling components are investigated. The practical application of the proposed models and methods is assessed using an industrial case example of an elevator system, and satisfactory results are obtained. The proposed method can be employed for analyzing different change propagation paths and their optimization in terms of overall costs.
This paper gives a definition of moving path planning based on summing up planning of 3D path, and points out planning method of moving path in real terrain is different from path planning in vertex graph. This paper ...
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ISBN:
(纸本)0780378652
This paper gives a definition of moving path planning based on summing up planning of 3D path, and points out planning method of moving path in real terrain is different from path planning in vertex graph. This paper simplifies the problem firstly, emphasizing on simplifying shape of obstacle, and seeing encasing box of planar convex polygon as simplified obstacle, and puts forward using modified dijkstra algorithm to solve the problem, and we submits an algorithm of creating linking matrix of vertices of encasing box. Experiments prove the method can get shortest path and have preferable applied importance.
This paper tackles the problem of performing persistent and complete coverage of a target space with a minimum number of Unmanned Aerial Vehicles (UAVs). The UAVs are required to preferentially visit subareas of inter...
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This paper tackles the problem of performing persistent and complete coverage of a target space with a minimum number of Unmanned Aerial Vehicles (UAVs). The UAVs are required to preferentially visit subareas of interest with higher frequency than the rest of the surveillance area within a predefined time threshold. A Minimum Spanning Tree based recursive algorithm is firstly proposed to estimate the upper bound of minimum number of UAVs for area coverage with visiting frequency constraints. Then an autonomous path planning strategy is proposed for persistent coverage, where a combinatorial priority function is designed as the goal assignment strategy and a modified dijkstra algorithm is applied as the goal planning to obtain the optimum path. Finally, computer simulations have been conducted for the evaluation of the proposed solution, and the obtained results show that these algorithms can compute valid and sound solutions under different setups for the UAVs. (c) 2022 Elsevier B.V. All rights reserved.
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