1,721,193 research outputs found
Shortest paths in randomly time varying networks
No full textA dynamic single-source single-destination shortest path problem on a directed graph is considered. The edge lengths are not constant, but they change as a function of time in a random way. The problem is modeled as a multi-stage decision process and solved by using a re-optimization method that solves the ι.th stage using the results of the solution of the (ι-1).th one. An algorithm, called the dynamical shortest path algorithm, is proposed for solving the global problem either finding a solution or detecting that the problem is infeasible and an upper bound on its running time is found. Numerical examples are reported in order to show the effectiveness of the method
Graph collapsing in shortest path Auction algorithms
No full textIn this paper we consider the problem of finding a shortest path from a source node to a fixed target node (SSP) or to all the nodes (SPT) on a directed graph. A family of algorithms which derives from the known auction algorithm is introduced. The key feature of these algorithms is based on topological transformations operated on the graphs that replace an optimal sub-path with a single arc of the same length (graph collapsing concept). The same idea is applied both to the standard auction algorithm and to a modified version of the algorithm. In the last mentioned case a good saving in computation cost is obtained as shown by the reported numerical examples
Rendezvous of mobile robots in unknown environment via graph optimization approach
No full textThe problem of finding a path for the motion of two autonomous mobile robots from a starting point to meet the other robot in a two dimensional domain is considered in the presence of arbitrary shaped obstacles. No a priori information is known in advance about the geometry and the dimensions of the workspace nor about the number, extension and location of obstacles. The robots have a sensing device that detects all obstacles or pieces of walls lying beyond a fixed view range. The problem is embedded in a graph optimization framework and a new algorithm is proposed, characterized by little computer power requirements. Theoretical and practical aspects of the algorithm are investigated
Vehicle Routing Problem in Optimal Warehouse Management for Flexible Manufacturing Plants
No full textIn this paper, a particular Vehicle Routing Problem is described realted to storage management problems for a flexible manufactuting system (FMS). It is formulated as the problem of picking a given number of different types of objects contained in a list from a set of locations where objects are stored in given quantities. This is accomplished by a set of tours traveled by a vehicle of fixed capacity starting and ending at the same given location. The goal is to minimize the total length of all tours
Complexity and experimental evaluation of primal-dual shortest path tree algorithms
No full textThis work describes several auction algorithms for shortest path problems
Network optimization for sensor based robotic navigation with moving obstacles
No full textThe problem of finding a path for the motion of a small mobile robot from a starting point to a fixed target in a two dimensional domain is considered in the presence of moving arbitrary shaped obstacles. No a priori information is known in advance about the geometry and the dimensions of the workspace nor about the number, extension and location of obstacles. The robot has a sensing device that detects all obstacles or pieces of walls lying beyond a fixed view range. A discrete version of the problem is solved by an iterative algorithm that at any iteration step finds the smallest path length from the actual point to the target with respect to the actual knowledge about the obstacles, then the robot is steered along the path until a new obstacle point interfering with the path is found, at this point a new iteration is started. Such an algorithm stops in a number of steps depending on the geometry, finding a solution for the problem or detecting that the problem is unfeasible. Since the algorithm must be applied on line, the effectiveness of the method depends strongly on the efficiency of the optimization step
Vehicle Routing Problem in Optimal Warehouse Management for Flexible Manufacturing Plants
No full textIn this paper, a particular Vehicle Routing Problem is described realted to storage management problems for a flexible manufactuting system (FMS). It is formulated as the problem of picking a given number of different types of objects contained in a list from a set of locations where objects are stored in given quantities. This is accomplished by a set of tours traveled by a vehicle of fixed capacity starting and ending at the same given location. The goal is to minimize the total length of all tours
Network optimization for sensor based robotic navigation with moving obstacles
No full textThe problem of finding a path for the motion of a small mobile robot from a starting point to a fixed target in a two dimensional domain is considered in the presence of moving arbitrary shaped obstacles. No a priori information is known in advance about the geometry and the dimensions of the workspace nor about the number, extension and location of obstacles. The robot has a sensing device that detects all obstacles or pieces of walls lying beyond a fixed view range. A discrete version of the problem is solved by an iterative algorithm that at any iteration step finds the smallest path length from the actual point to the target with respect to the actual knowledge about the obstacles, then the robot is steered along the path until a new obstacle point interfering with the path is found, at this point a new iteration is started. Such an algorithm stops in a number of steps depending on the geometry, finding a solution for the problem or detecting that the problem is unfeasible. Since the algorithm must be applied on line, the effectiveness of the method depends strongly on the efficiency of the optimization step
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