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Feasibility Studies on Guidance and Global Path Planning for Wind-Assisted Montgolfiere in Titan

IEEE SYSTEMS JOURNAL 2014年第4期8卷 1112-1125页

作者： Fathpour, Nanaz Blackmore, Lars Kuwata, Yoshiaki Assad, Christopher Wolf, Michael T. Newman, Claire Elfes, Alberto Reh, Kim CALTECH Jet Prop Lab Pasadena CA 91109 USA Space Explorat Technol Hawthorne CA 90250 USA Ashima Res Pasadena CA 91106 USA CSIRO Pullenvale Qld 4069 Australia

Recent studies have proposed the use of a hot-air (Montgolfiere) balloon for possible exploration of Titan, Mars, and Venus. One of NASA's Outer Planet Flagship mission concepts is the Titan Saturn System Mission, which would be a joint NASA-ESA partnership that plans to employ a Montgolfiere along with a lake lander and an orbiter. This Montgolfiere would circle Titan, investigating how Titan and Saturn operate as a system and determining how far prebiotic chemistry has developed. This paper provides a new method to analyze global path planning with balloons on Titan. The main objective of this study is to determine whether the balloon could reach a particular location of interest from a given initial position at its insertion point in the atmosphere using the wind fields on Titan. This study is the first comprehensive analysis and quantitative assessment of balloon guidance in Titan that proactively uses wind for global path planning. The paper will investigate and characterize the guidance and path-planning performance of Montgolfiere balloons in Titan's atmosphere for lower atmosphere and surface exploration in the presence of variable wind fields using the Titan Weather Research and Forecasting (TitanWRF) model. The study focuses on determining the altitude profile that a balloon could follow, using variable wind fields, in order to reach its target most quickly. Our results show that a simple unpropelled Montgolfiere without horizontal actuation would be able to reach a broad array of science targets within the constraints of the wind field. The study also indicates that even a small amount of horizontal thrust allows the balloon to reach any area of interest on Titan, in a fraction of the time needed by the unpropelled balloon. The results show that using the Titan wind field allows a balloon to significantly extend its scientific reach and that a Montgolfiere (unpropelled or propelled) is a highly desirable architecture that can significantly enhance the sci

关键词： Decomposition algorithm general purpose guidance algorithm global reachability graph search algorithm loitering Markov decision process Montgolfiere path planning reachability maps Titan TitanWRF

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Application of Minimum Spanning Tree algorithm for Network Reduction of Distribution Systems

Application of Minimum Spanning Tree Algorithm for Network R...

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North American Power Symposium (NAPS)

作者： Nagarajan, Adarsh Ayyanar, Raja Arizona State Univ Dept Elect Engn Tempe AZ 85287 USA

ISBN: (纸本)9781479959044

This paper demonstrates the application of a graph search algorithm for the network reduction of the distribution feeder. The purpose behind the network-reduction is to develop a reduced distribution system to facilitate the dynamic analysis of the feeders with high penetration of PV generators. Dynamic analysis requires modeling of the distribution feeders in the electromagnetic transient programs for understanding the transients. Performing the transient analysis on large distribution feeders with high PV penetration is time intensive and impracticable. To aid this purpose a network-reduction algorithm for the distribution feeder is proposed in this paper. The objective is to develop a reduced distribution system to support the study of long-term transients of the PV inverters such as - interaction with other control devices (capacitor banks and PV generators), cloud transients, and voltage flicker. This paper proposes a novel network-reduction technique, based on a network-flow procedure, which is referred to as Minimum Spanning Tree (MST) with additional capabilities. The network reduction proposed in this paper selectively retains the laterals and additionally accommodates the reactive power generation from the cable capacitance to the loads. The proposed algorithm will serve as an interface for modeling the feeder from the GIS database to the transient analysis tool.

关键词： EMTP cables (electric) capacitance distribution networks graph theory invertors power system transients reactive power solar cells transient analysis GIS database MST PV generators PV inverters PV penetration cable capacitance cloud transients distribution feeder dynamic analysis electromagnetic transient programs graph search algorithm long-term transients minimum spanning tree algorithm network-flow procedure network-reduction algorithm reactive power generation reduced distribution system transient analysis tool voltage flicker algorithm design and analysis Analytical models Generators Heuristic algorithms Load modeling Power cables Transient analysis distribution feeder Transient analysis Network reduction Voltage flicker Inventors algorithm design and analysis Dynamic analysis power system transients dispensing system Electromagnetic Transients Program cable capacitance Power cables dynamos Load modeling Reactive power

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A General Label search to investigate classical graph search algorithms

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DISCRETE APPLIED MATHEMATICS 2011年第2-3期159卷 128-142页

作者： Krueger, R. Simonet, G. Berry, A. Univ Montpellier 2 LIRMM CNRS F-34392 Montpellier France Univ Toronto Dept Comp Sci Toronto ON M5S 3G4 Canada LIMOS F-63177 Aubiere France

Many graph search algorithms use a labeling of the vertices to compute an ordering of the vertices. We generalize this idea by devising a general vertex labeling algorithmic process called General Label search (GLS), which uses a labeling structure which, when specified, defines specific algorithms. We characterize the vertex orderings computable by the basic types of searches in terms of properties of their associated labeling structures. We then consider performing graph searches in the complement without computing it, and provide characterizations for some searches, but show that for some searches such as the basic Depth-First search, no algorithm of the GLS family can exactly find all the orderings of the complement. Finally, we present some implementations and complexity results of GLS on a graph and on its complement. (C) 2010 Elsevier B.V. All rights reserved.

关键词： graph search algorithm graph labeling algorithm Breadth First search Depth First search LexBFS

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On the importance of graph search algorithms for DRGEP-based mechanism reduction methods

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COMBUSTION AND FLAME 2011年第8期158卷 1439-1443页

作者： Niemeyer, Kyle E. Sung, Chih-Jen Univ Connecticut Dept Mech Engn Storrs CT 06269 USA Case Western Reserve Univ Dept Mech & Aerosp Engn Cleveland OH 44106 USA

The importance of graph search algorithm choice to the directed relation graph with error propagation (DRGEP) method is studied by comparing basic and modified depth-first search, basic and R-value-based breadth-first search (RBFS), and Dijkstra's algorithm. By using each algorithm with DRGEP to produce skeletal mechanisms from a detailed mechanism for n-heptane with randomly-shuffled species order, it is demonstrated that only Dijkstra's algorithm and RBFS produce results independent of species order. In addition, each algorithm is used with DRGEP to generate skeletal mechanisms for n-heptane covering a comprehensive range of autoignition conditions for pressure, temperature, and equivalence ratio. Dijkstra's algorithm combined with a coefficient scaling approach is demonstrated to produce the most compact skeletal mechanism with a similar performance compared to larger skeletal mechanisms resulting from the other algorithms. The computational efficiency of each algorithm is also compared by applying the DRGEP method with each search algorithm on the large detailed mechanism for n-alkanes covering n-octane to n-hexadecane with 2115 species and 8157 reactions. Dijkstra's algorithm implemented with a binary heap priority queue is demonstrated as the most efficient method, with a CPU cost two orders of magnitude less than the other search algorithms. (C) 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

关键词： Mechanism reduction Skeletal mechanism DRG DRGEP graph search algorithm Dijkstra's algorithm

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The Application of an Intelligent Crane Control System

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IFAC Proceedings Volumes 2012年第24期45卷 280-285页

作者： J. Smoczek J. Szpytko P. Hyla AGH University of Science and Technology Faculty of Mechanical Engineering and Robotics Av. A. Mickiewicza 30 PL 30-059 Krakow Poland

The paper describes the crane control application and method of designing the anti-sway crane control system based on the fuzzy logic and pole placement method. The crane control system consists of the machine vision system used to contactless measure the sway of a payload, and the untypical stereovision system based on a single camera used to capture the stereo pair of crane workspace snapshots. The method of crane workspace identification based on the stereovision system, and safe and time-optimal path planning for a payload utilizing the heuristic graph search algorithm is delivered in the paper, together with the hardware and software description of the control application.

关键词： crane control system machine vision graph search algorithm fuzzy logic pole placement

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Gap Detection in Endoscopic Video Sequences Using graphs

Gap Detection in Endoscopic Video Sequences Using Graphs

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33rd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBS)

作者： Behrens, Alexander Takami, Masato Gross, Sebastian Aach, Til Rhein Westfal TH Aachen Inst Imaging & Comp Vis Fac Elect Engn & Informat Technol Aachen Germany

ISBN: (纸本)9781424441228

In minimal invasive surgery (MIS) a complete and seamless inspection of organs, e. g. the urinary bladder, using video endoscopes is often required for diagnostics. Since the endoscope is usually guided by free-hand, it is difficult to ensure a sequence of seamless frame transitions. Also 2-D panoramic images showing an extended field of view (FOV) do not provide always reliable results, since their interpretations are limited by potentially strong geometric distortions. To overcome these limitations and provide a direct verification method, we develop a gap detection algorithm using graphs. Exploiting the motion information of the applied zig-zag scan, we construct a graph representation of the video sequence. Without any explicit global image visualization our graph search algorithm identifies reliably frame discontinuities, which would lead to holes and slit artifacts in a panoramic view. The algorithm shows high detection rates and provides a fast method to verify frame discontinuities in the whole video sequence. Missed regions are highlighted by local image compositions which can be displayed during the intervention for assistance and inspection control.

关键词： Bladder Endoscopes Image edge detection Robustness Signal processing algorithms Video sequences Visualization assistance control endoscopes endoscopic video sequence gap detection algorithm graph representation graph search algorithm graph theory image ma

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Live-wire-based segmentation using similarities between corresponding image structures

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COMPUTERIZED MEDICAL IMAGING AND graphICS 2007年第7期31卷 549-560页

作者： Faerber, Matthias Ehrhardt, Jan Handels, Heinz Univ Hamburg Ctr Med Dept Med Informat D-20246 Hamburg Germany

A live-wire-based segmentation method that exploits similarities of corresponding object contours is presented. The method accelerates the segmentation process transferring anchor points of segmented reference contours to unsegmented target slices automatically. The target contours are created using the live-wire algorithm trained by features of the reference contours. An automatic contour correction improves the segmentation. Only few user interactions with an intuitive contour editor are necessary. The evaluation using intra- and interpatient transfer shows that 51-73% of interaction time can be saved compared to normal live-wire preserving the segmentation quality. (c) 2007 Elsevier Ltd. All rights reserved.

关键词： segmentation live-wire contour extraction graph search algorithm image similarity

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Automatic atlas-based contour extraction of anatomical structures in medical images

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International Congress Series 2005年 1281卷 272-277页

作者： Färber, Matthias Ehrhardt, Jan Handels, Heinz Department of Medical Informatics University Medical Center Hamburg-Eppendorf Hamburg Germany

We present an extension of the live-wire approach to an automatic segmentation method. Similarities between anatomical structures in different patient data are exploited by transferring structure outlines from atlas to patient data. After preprocessing via affine registration methods, the automatic segmentation is done slice by slice. Atlas seed points are relocated in each patient slice and then connected by cost-trained live-wires. After the automatic contour extraction, an efficient graph search algorithm facilitates the interactive adjustment of the contours created. The evaluation with hip CT data showed that the tool simplifies the segmentation of anatomical hip structures because 51% of interaction time could be saved maintaining the segmentation quality compared to manually created segmentations. © 2005 CARS and Elsevier B.V.

关键词： Anatomical structures Contour extraction graph search algorithm Live-wire Segmentation

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