We present a generic distributed algorithm for solving silents tasks such as shortest path calculus, depth-first-search tree construction, best reliable transmitters, in directed networks where communication may be only unidirectional. Our solution is written for the asynchronous message passing communication model, and tolerates multiple kinds of failures (transient and intermittent). First, our algorithm is self-stabilizing, so that it recovers correct behavior after finite time starting from an arbitrary global state caused by a transient fault. Second, it tolerates fair message loss, finite message duplication, and arbitrary message reordering, during both the stabilizing phase and the stabilized phase. This second property is most interesting since, in the context of unidirectional networks, there exists no self-stabilizing reliable data-link protocol. The correctness proof subsumes previous proofs for solutions in the simpler reliable shared memory communication model.
{"title":"Self-Stabilization with r-Operators revisited","authors":"S. Delaët, B. Ducourthial, S. Tixeuil","doi":"10.2514/1.19848","DOIUrl":"https://doi.org/10.2514/1.19848","url":null,"abstract":"We present a generic distributed algorithm for solving silents tasks such as shortest path calculus, depth-first-search tree construction, best reliable transmitters, in directed networks where communication may be only unidirectional. Our solution is written for the asynchronous message passing communication model, and tolerates multiple kinds of failures (transient and intermittent). \u0000 \u0000First, our algorithm is self-stabilizing, so that it recovers correct behavior after finite time starting from an arbitrary global state caused by a transient fault. Second, it tolerates fair message loss, finite message duplication, and arbitrary message reordering, during both the stabilizing phase and the stabilized phase. This second property is most interesting since, in the context of unidirectional networks, there exists no self-stabilizing reliable data-link protocol. The correctness proof subsumes previous proofs for solutions in the simpler reliable shared memory communication model.","PeriodicalId":207100,"journal":{"name":"Journal of Aerospace Computing Information and Communication","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132213547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
†This paper presents a simplified analysis of probabilistic aircraft conflict management in the context of a future vision for the air traffic management (ATM) system. In such a future vision, the ATM system may include four-dimensional (4D) flight contracts that define conformance limits for aircraft position as a function of time, routine use of probabilistic approaches to pro-actively manage air traffic, and reduced aircraft separation standards. In the future ATM system, probabilities of conflict across multiple potential conflicting aircraft might be used as a means to assess and manage traffic situations with a longer look-ahead than is used in the current ATM system. We begin the analysis of such a future system by analyzing two-aircraft potential-conflict scenarios in the horizontal plane. We show how Monte Carlo simulation techniques can be applied to estimate probabilities of conflict (before deliberate actions are taken to resolve the conflicts) and how these probabilities depend on aircraft separation standards. Results are generated for multiple identical potential conflict pairs, with probabilities estimated as functions of angle of incidence. In order to better understand the implications of the results for future ATM operations, the modeling methodology is applied to find minimum speed changes and lateral deviations needed to achieve specified target probabilities of conflict across multiple independent potential conflict pairs. The analysis shows, in simplified scenarios, how application of appropriate speed changes and position deviations could be used to pro-actively manage air traffic, with probability of conflict serving as a metric. We draw preliminary implications for future ATM operations based on this simplified analysis. We also discuss how this analysis illustrates the role of relatively simple modeling approaches to systems engineering involving complex systems like the future ATM system.
{"title":"Probabilistic Aircraft Conflict Analysis for a Vision of the Future Air Traffic Management System","authors":"L. Wojcik","doi":"10.2514/6.2005-7474","DOIUrl":"https://doi.org/10.2514/6.2005-7474","url":null,"abstract":"†This paper presents a simplified analysis of probabilistic aircraft conflict management in the context of a future vision for the air traffic management (ATM) system. In such a future vision, the ATM system may include four-dimensional (4D) flight contracts that define conformance limits for aircraft position as a function of time, routine use of probabilistic approaches to pro-actively manage air traffic, and reduced aircraft separation standards. In the future ATM system, probabilities of conflict across multiple potential conflicting aircraft might be used as a means to assess and manage traffic situations with a longer look-ahead than is used in the current ATM system. We begin the analysis of such a future system by analyzing two-aircraft potential-conflict scenarios in the horizontal plane. We show how Monte Carlo simulation techniques can be applied to estimate probabilities of conflict (before deliberate actions are taken to resolve the conflicts) and how these probabilities depend on aircraft separation standards. Results are generated for multiple identical potential conflict pairs, with probabilities estimated as functions of angle of incidence. In order to better understand the implications of the results for future ATM operations, the modeling methodology is applied to find minimum speed changes and lateral deviations needed to achieve specified target probabilities of conflict across multiple independent potential conflict pairs. The analysis shows, in simplified scenarios, how application of appropriate speed changes and position deviations could be used to pro-actively manage air traffic, with probability of conflict serving as a metric. We draw preliminary implications for future ATM operations based on this simplified analysis. We also discuss how this analysis illustrates the role of relatively simple modeling approaches to systems engineering involving complex systems like the future ATM system.","PeriodicalId":207100,"journal":{"name":"Journal of Aerospace Computing Information and Communication","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122242265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A self-stabilizing algorithm cannot detect by itself that stabilization has been reached. For overcoming this drawback Lin and Simon introduced the notion of an external observer: a set of processes, one being located at each node, whose role is to detect stabilization. Furthermore, Beauquier, Pilard and Rozoy introduced the notion of a local observer: a single observing entity located at an unique node. This entity is not allowed to detect false stabilization, must eventually detect that stabilization is reached, and must not interfere with the observed algorithm. We introduce here the notion of probabilistic observer which realizes the conditions above only with probability 1. We show that computing the size of an anonymous ring with a synchronous self-stabilizing algorithm cannot be observed deterministically. We prove that some synchronous self-stabilizing solution to this problem can be observed probabilistically.
{"title":"Observing Locally Self-Stabilization in a Probabilistic Way","authors":"J. Beauquier, Laurence Pilard, Brigitte Rozoy","doi":"10.2514/1.19858","DOIUrl":"https://doi.org/10.2514/1.19858","url":null,"abstract":"A self-stabilizing algorithm cannot detect by itself that stabilization has been reached. For overcoming this drawback Lin and Simon introduced the notion of an external observer: a set of processes, one being located at each node, whose role is to detect stabilization. Furthermore, Beauquier, Pilard and Rozoy introduced the notion of a local observer: a single observing entity located at an unique node. This entity is not allowed to detect false stabilization, must eventually detect that stabilization is reached, and must not interfere with the observed algorithm. \u0000 \u0000We introduce here the notion of probabilistic observer which realizes the conditions above only with probability 1. We show that computing the size of an anonymous ring with a synchronous self-stabilizing algorithm cannot be observed deterministically. We prove that some synchronous self-stabilizing solution to this problem can be observed probabilistically.","PeriodicalId":207100,"journal":{"name":"Journal of Aerospace Computing Information and Communication","volume":"219 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122119123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel general method of the automatic selection of onboard star triplet, namely triplet regression selection algorithm (TRSA), which based on a new dynamical label visual magnitude threshold (DLVMT) model, is presented. By defining the label visual magnitude and the direction of the star triplet, the star triplet distribution is analyzed. Using the DLVMT to filter the star triplet set, a new catalog with uniform distribution of the triplets over the celestial sphere can be obtained. The DLVMT distribution function has been attained via the support vector machines (SVM) regression method. With the proposed sampling method, computer experiments were carried out. The experiment results demonstrate that the triplet database obtained by the proposed algorithm has a couple of advantages, including fewer total numbers, smaller catalog size, and better distribution uniformity. 1 with which their operation capability to cover most or even all mission phases can be widened and all attitude data required for control can be supplied. The development of full autonomy of operation is also in accordance with the requirements of saving power, mass, and volume, and of limiting complexity and redundancy of onboard systems. An autonomous star tracker can operate and manage independently different mission phase requirements without support from other spacecraft units except the star image. These phases include the start up routine to determine the rough localization of the observed region of the sky, and the normal tracking mode following the initial acquisition procedure to estimate the high-precision attitude of the spacecraft. These different specific features are usually attained via software procedures. To obtain full autonomous attitude estimation, the star tracker should perform a prompt identification of the viewed star field by comparing observed star features and star characteristics stored in its onboard catalog. Once a correct match is made, there are reliable methods for generating good attitude estimation. Recently, many star pattern recognition (SPR) algorithms to generate a best match between the measured star pattern in the FOV and the subimage of the onboard catalog have been proposed. According to their respective identification approaches in the FOV, these algorithms can be divided into three classes. The first class of algorithms is the inter-star pair that has angular separation-based matching methods, in which the stars are treated as vertexes in a graph whose edges correspond to the angular separation between neighboring stars that could possibly share the same sensor FOV, such as those from Refs. 1 and 2. The grid algorithms, such as those from Refs. 3 and 4 belong to the second class of algorithms, in which the well-defined pattern determined by the surrounding star field has been associated with every star. The third class of algorithms is the developing neural networks-based recognition algorithms, 5 in which the star images of the FOV
{"title":"General Method of the Automatic Generation of Onboard Triplet","authors":"Zheng Sheng, Tian Jin-wen, Liu Jian","doi":"10.2514/1.2575","DOIUrl":"https://doi.org/10.2514/1.2575","url":null,"abstract":"A novel general method of the automatic selection of onboard star triplet, namely triplet regression selection algorithm (TRSA), which based on a new dynamical label visual magnitude threshold (DLVMT) model, is presented. By defining the label visual magnitude and the direction of the star triplet, the star triplet distribution is analyzed. Using the DLVMT to filter the star triplet set, a new catalog with uniform distribution of the triplets over the celestial sphere can be obtained. The DLVMT distribution function has been attained via the support vector machines (SVM) regression method. With the proposed sampling method, computer experiments were carried out. The experiment results demonstrate that the triplet database obtained by the proposed algorithm has a couple of advantages, including fewer total numbers, smaller catalog size, and better distribution uniformity. 1 with which their operation capability to cover most or even all mission phases can be widened and all attitude data required for control can be supplied. The development of full autonomy of operation is also in accordance with the requirements of saving power, mass, and volume, and of limiting complexity and redundancy of onboard systems. An autonomous star tracker can operate and manage independently different mission phase requirements without support from other spacecraft units except the star image. These phases include the start up routine to determine the rough localization of the observed region of the sky, and the normal tracking mode following the initial acquisition procedure to estimate the high-precision attitude of the spacecraft. These different specific features are usually attained via software procedures. To obtain full autonomous attitude estimation, the star tracker should perform a prompt identification of the viewed star field by comparing observed star features and star characteristics stored in its onboard catalog. Once a correct match is made, there are reliable methods for generating good attitude estimation. Recently, many star pattern recognition (SPR) algorithms to generate a best match between the measured star pattern in the FOV and the subimage of the onboard catalog have been proposed. According to their respective identification approaches in the FOV, these algorithms can be divided into three classes. The first class of algorithms is the inter-star pair that has angular separation-based matching methods, in which the stars are treated as vertexes in a graph whose edges correspond to the angular separation between neighboring stars that could possibly share the same sensor FOV, such as those from Refs. 1 and 2. The grid algorithms, such as those from Refs. 3 and 4 belong to the second class of algorithms, in which the well-defined pattern determined by the surrounding star field has been associated with every star. The third class of algorithms is the developing neural networks-based recognition algorithms, 5 in which the star images of the FOV ","PeriodicalId":207100,"journal":{"name":"Journal of Aerospace Computing Information and Communication","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124543052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：