On fast planning of suboptimal paths amidst polygonal obstacles in plane

AbstractThe problem of planning a path for a point robot from a source point s to a destination point d so as to avoid a set of polygonal obstacles in plane is considered. Using well-known methods, a shortest path from s to d can be computed with a time complexity of O(n2) where n is the total number of obstacle vertices. The focus here is in 1.(a) planning paths faster at the expense of setting for suboptimal path lengths and2.(b) performance analysis of simple and/or well-known suboptimal methods. A method that enables a hierarchical implementation of any path planning algorithm with no increase in the worst-case time complexity, is presented; this implementation enables fast planning of simple paths. Then methods are presented based on the Voronoi diagrams, trapezoidal decomposition and triangulation, which compute (suboptimal) paths in O(n√log n) time with the preprocessing costs of O(n log n), O(n2) and O(n log n), respectively. Using existing navigational algorithms for unknown terrains, algorithms that run in O(n log n) time (after preprocessing) and yield suboptimal paths, are presented. For all these algorithms, upper bounds on the path lengths are estimated in terms of the shortest of the obstacles, etc

Optimizing Network Performance of Computing Pipelines in Distributed Environments

Supporting high performance computing pipelines over wide-area networks is critical to enabling large-scale distributed scientific applications that require fast responses for interactive operations or smooth flows for data streaming. We construct analytical cost models for computing modules, network nodes, and communication links to estimate the computing times on nodes and the data transport times over connections. Based on these time estimates, we present the Efficient Linear Pipeline Configuration method based on dynamic programming that partitions the pipeline modules into groups and strategically maps them onto a set of selected computing nodes in a network to achieve minimum end-to-end delay or maximum frame rate. We implemented this method and evaluated its effectiveness with experiments on a large set of simulated application pipelines and computing networks. The experimental results show that the proposed method outperforms the Streamline and Greedy algorithms. These results, together with polynomial computational complexity, make our method a potential scalable solution for large practical deployments

System Design and Algorithmic Development for Computational Steering in Distributed Environments

Supporting visualization pipelines over wide-area networks is critical to enabling large-scale scientific applications that require visual feedback to interactively steer online computations. We propose a remote computational steering system that employs analytical models to estimate the cost of computing and communication components and optimizes the overall system performance in distributed environments with heterogeneous resources. We formulate and categorize the visualization pipeline configuration problems for maximum frame rate into three classes according to the constraints on node reuse or resource sharing, namely no, contiguous, and arbitrary reuse. We prove all three problems to be NP-complete and present heuristic approaches based on a dynamic programming strategy. The superior performance of the proposed solution is demonstrated with extensive simulation results in comparison with existing algorithms and is further evidenced by experimental results collected on a prototype implementation deployed over the Internet

INTEGRATED WEED MANAGEMENT IN FCV TOBACCO ( NICOTIANA TABACUM ) GROWN UNDER IRRIGATED ALFISOLS

Not AvailableTobacco yield loss due to weed competition is the most important factor that causes yield and quality reduction. Due to the scarcity of human labour, manual weeding is becoming difficult in tobacco. In situations where manual weeding and intercultural operations are not done on time due to adverse soil and weather conditions use of herbicides is the obvious choice in FCV tobacco weed management. Hence, this study was proposed by inclusion of herbicides in weed management in FCV tobacco under irrigated alfisols. The field experiment was conducted in RBD with 10 treatments viz.1. Pre-plant soil incorporation (PPI) of Pendimethalin 3 days before planting + Quizalofop-ethyl 30 DAP 2. PPI of Pendimethalin 3 days before planting + Quizalofop-ethyl 75 days after planting(DAP) 3. Post emergence application (PEA) of Quizalofop-ethyl at 15 DAP 4. PEA of Quizalofop-ethyl at 60 DAP 5. PEA of Quizalofopethyl at 75 DAP 6. PEA of Quizalofop-ethyl at 15 + 75 DAP 7. PEA of Quizalofop-ethyl at 60 + 90 DAP 8. PEA of Quizalofop-ethyl at 75 + 125 DAP 9. Weed free check 10. Un weeded check integrated with inercultural operations and replicated thrice. Statistically lower weed dry matter production was recorded wherever herbicide application was done at 30, 60, 90 days of planting and at harvest in tobacco. Spraying of Quizalofop-ethyl at 15+75 days after planting effectively controlled the grassy weeds and also gave higher yields when compared to weed free check. Leaf Reducing sugars, nicotine and Chlorides were well within the desirable limits. Integrated weed management practices could not influenced the soil chemical properties significantly. Two post emergence sprays of Quizalofop-ethyl @ 60 g a.i./ha at 15 and 75 DAP can be used in integrated weed management along with intercultures to control monocot weeds which are dominant in the irrigated alfisols.Not Availabl