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Self-Stabilizing Prefix Tree Based Overlay Networks

INTERNATIONAL JOURNAL OF FOUNDATIONS OF COMPUTER SCIENCE 2016年第5期27卷 607-630页

作者： Caron, Eddy Datta, Ajoy K. Petit, Franck Tedeschi, Cedric Univ Lyon LIP UMR CNRS ENS Lyon UCB LyonINRIA 5668 Lyon France Univ Nevada Las Vegas Sch Comp Sci Las Vegas NV 89154 USA UPMC Sorbonne Univ LIP6 UMR 7606 Paris France Univ Rennes 1 INRIA Rennes France

Computing over large platforms calls for the ability to maintain distributed structures at large scale. Among the many different structures proposed in this context, the prefix tree structure has been identified as an adequate one for indexing and retrieving information. One weakness of using such a distributed structure stands in its poor native fault tolerance, leading to the use of preventive costly mechanisms such as replication. Self-stabilization is a suitable approach to design reliable solutions for dynamic systems, and was recently enhanced with new models to be able to deal with large scale dynamic platforms. A self-stabilizing system is guaranteed to reach a correct configuration, whatever its initial state is. Following this path, it is becoming possible to make distributed structures self-stabilizing at large scale. In this paper, we focus on making tries self-stabilizing over such platforms, and propose a self-stabilizing maintenance algorithm for a prefix tree using a message passing model. The proof of self-stabilization is provided, and simulation results are given, to better capture its performaitces. Still based on simulations, we provide evidences that the protocol, beyond its capacity to repair the structure, can significantly improve the system's availability, even when the system is not yet stabilized.

关键词： distributed algorithms overlay networks prefix trees service discovery fault-tolerance self-stabilization

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Fast Image Segmentation Using Two-Dimensional Otsu Based on Estimation of Distribution Algorithm

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JOURNAL OF ELECTRICAL AND COMPUTER ENGINEERING 2017年第1期2017卷 1-12页

作者： Wang, Wuli Duan, Liming Wang, Yong Chongqing Univ Engn Res Ctr Ind Com Tomog Nondestruct Testing Educ Minist China Chongqing Peoples R China Chongqing Univ Coll Mech Engn Chongqing Peoples R China China Univ Petr East China Coll Informat & Control Engn Qingdao Peoples R China Chongqing Huayu Heavy Machinery & Elect Co Ltd Chongqing Peoples R China

Traditional two-dimensional Otsu algorithm has several drawbacks;that is, the sum of probabilities of target and background is approximate to 1 inaccurately, the details of neighborhood image are not obvious, and the computational cost is high. In order to address these problems, a method of fast image segmentation using two-dimensional Otsu based on estimation of distribution algorithm is proposed. Firstly, in order to enhance the performance of image segmentation, the guided filtering is employed to improve neighborhood image template instead of mean filtering. Additionally, the probabilities of target and background in two-dimensional histogram are exactly calculated to get more accurate threshold. Finally, the trace of the interclass dispersion matrix is taken as the fitness function of estimation of distributed algorithm, and the optimal threshold is obtained by constructing and sampling the probability model. Extensive experimental results demonstrate that our method can effectively preserve details of the target, improve the segmentation precision, and reduce the running time of algorithms.

关键词： distributed algorithms SEGMENTATION (Image processing) HISTOGRAMS SAMPLING (Statistics) TWO-dimensional models

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COMBINING GENETIC PROGRAMMING AND MODEL-DRIVEN DEVELOPMENT

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INTERNATIONAL JOURNAL OF COMPUTATIONAL INTELLIGENCE AND APPLICATIONS 2009年第1期8卷 37-52页

作者： Weise, Thomas Zapf, Michael Khan, Mohammad Geihs, Kurt Univ Kassel Distributed Syst Grp D-34121 Kassel Germany

Genetic programming (GP) is known to provide good solutions for many problems like the evolution of network protocols and distributed algorithms. In most cases it is a hardwired module of a design framework assisting the engineer in optimizing specific aspects in system development. In this article, we show how the utility of GP can be increased remarkably by isolating it as a component and integrating it into the modeldriven software development process. Our GP framework produces XMI-encoded UML models that can easily be loaded into widely available modeling tools, which in turn offer code generation as well as additional analysis and test capabilities. We use the evolution of a distributed election algorithm as an example to illustrate how GP can be combined with model-driven development (MDD).

关键词： Genetic programming evolutionary algorithms model-driven development model-driven architecture UML XMI MOFScript distributed systems distributed algorithms sensor networks

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Delay-efficient Routing across High-throughput Wireless Network Clusters

Delay-efficient Routing across High-throughput Wireless Netw...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Phanish, Deepa Coyle, Edward J. Georgia Inst Technol Sch Elect & Comp Engn Atlanta GA 30332 USA

ISBN: (纸本)9781538617342

Wireless sensor and adhoc networks are hierarchically clustered for energy-efficiency, while gathering and aggregating data at the central clusterhead. Subsequent long-range communications from the clusterheads cause large-scale interference and energy-hole problems around them. It is thus better to have packets forwarded via short-range multi-hop routes between the clusterheads at different levels of the hierarchy. In order to discover the most optimal routes that serve the purpose, paths that minimize the inter-cluster routing delay within latticed clusters are analyzed. Consequently, a lowdelay, energy-balancing distributed algorithm for routing across clusters is developed, which outperforms shortest path routing in high throughput networks. A parametric study comprising large-scale network evaluations is performed by developing an NS-3 based simulator.

关键词： Routing Delays Routing protocols Throughput Conferences Wireless networks distributed algorithms

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Robustness of class-based path-vector systems

Robustness of class-based path-vector systems

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International Conference on Network Protocols

作者： A.D. Jaggard V. Ramachandran Department of Mathematics Tulane University USA Department of Computer Science Yale University USA

Griffin, Jaggard, and Ramachandran [2004] introduced a framework for studying design principles for path-vector protocols, such as the border gateway protocol (BGP) used for inter-domain routing in the Internet. They outlined how their framework could describe hierarchical-BGP-like systems in which routing at a node is determined by the relationship with the next-hop node on a path (e.g., an ISP-peering relationship) and some additional scoping rules (e.g., the use of backup routes). The robustness of these class-based path-vector systems depends on the presence of a global constraint on the system, but an adequate constraint has not yet been given in general. In This work, we give the best-known sufficient constraint that guarantees robust convergence. We show how to generate this constraint from the design specification of the path-vector system. We also give centralized and distributed algorithms to enforce this constraint, discuss applications of these algorithms, and compare them to algorithms given in previous work on path-vector protocol design.

关键词： Robustness Routing protocols Internet distributed algorithms Algorithm design and analysis Peer to peer computing Mathematics Computer science Convergence IP networks

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Set Stability of Phase-Coupled Agents in Discrete Time

Set Stability of Phase-Coupled Agents in Discrete Time

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2008 American Control Conference (ACC), vol.6

作者： Daniel J. Klein Kristi A. Morgansen Department of Aeronautics and Astronautics University of Washington Seattle WA USA

The work in this paper addresses the stability of a discretized version of the well-known phase-coupled oscillator model from the physics community. The main contribution is a pair of stability proofs for a system of N phase-coupled agents. The first proof establishes asymptotic stability to the balanced set for a range K(DELTA)T, where K is a coupling gain and (DELTA)T is the time discretization. In the second proof, a reference vector in the unit ball is introduced and asymptotic stability of the phase centroid to the reference vector is guaranteed, again for a range of K(DELTA)T. These results are of particular interest to researchers looking to apply phase coupling to systems in which continuous communication is not possible. Possible applications of this work include cooperative target tracking and modeling of neurological processes and of biological aggregations.

关键词： Target tracking Physics Asymptotic stability Frequency synchronization Local oscillators Vehicles Biological system modeling Solids distributed algorithms Multiagent systems

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Lower Bounds for Additive Spanners, Emulators, and More

Lower Bounds for Additive Spanners, Emulators, and More

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Annual IEEE Symposium on Foundations of Computer Science

作者： David P. Woodruff Tsinghua University China

An additive spanner of an unweighted undirected graph G with distortion d is a subgraph H such that for any two vertices u,v isin G, we have delta H (u, v) les delta G (u, v) + d. For every k = O((ln n)/( ln ln n)), we construct a graph G on vertices for which any additive spanner of G with distortion 2k - 1 has Omega((1/k)n 1 + 1 k/) edges. This matches the lower bound previously known only to hold under a 1963 conjecture of Erdos. We generalize our lower bound in a number of ways. First, we consider graph emulators introduced by Dor, Halperin, and Zwick (FOCS, 1996), where an emulator of an unweighted undirected graph G with distortion d is like an additive spanner except H may be an arbitrary weighted graph such that delta G (u, v) ges delta G (u, v) ges delta G (u, v) + d. We show a lower bound of Omega((1/k 2 )n 1 + 1 k/) edges for distortion- (2k - 1) emulators. These are the first non-trivial bounds for k > 3. Second, we parameterize our bounds in terms of the minimum degree of the graph. Namely, for minimum degree n 1 k + c/ for any c ges 0, we prove a bound of Omega((1/k)n 1 + 1 k - c(1 + 2/(k - 1))/) for additive spanners and Omega((1/k 2 )n 1 + 1 k - c(1 + 2/(k - 1))/) for emulators. For k = 2 these can be improved to OmegaQ(n (3/2) - c ). This partially answers a question of Baswana et al. (SODA, 2005) for additive spanners. Finally, we continue the study of pair-wise and source-wise distance preservers defined by Coppersmith and Elkin (SODA, 2005) by considering their approximate variants and their relaxation to emulators. We prove the first lower bounds for such graphs

关键词： IP networks Routing protocols distributed algorithms Upper bound

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Source Location Anonymity for Sensor Networks

Source Location Anonymity for Sensor Networks

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Consumer Communications and Networking Conference, CCNC IEEE

作者： Ali Abbasi Ahmad Khonsari Mohammad S. Talebi ECE Department University of Tehran Tehran Iran ECE Department School of Computer Science University of Tehran Iran School of Computer Science Institute of Studies in Theoretical Physics and Mathematics Iran

Motivated by applications like sensor, peer to peer networks there has been growing interest in monitoring large scale distributed systems. In these applications, source location anonymity is an attractive and critical security property. Most of prior works assumed a weak adversary model where the adversary sees only local network traffic, but here we consider source anonymity against a global eavesdropper. Attaining location unobservability under global attacker is very difficult and expensive to achieve, because sensor networks are very limited in resources. In this work we propose a distributed algorithm to mix real event traffic with carefully chosen dummy traffic to hide the real event traffic pattern. We assume that we have fixed amount of resources to send dummy traffic and we try to share it among sensors so as to maximize the degree of anonymity of the system. Through simulation, we illustrate that the proposed technique is efficient in protecting location information from the eavesdropper.

关键词： Position measurement Telecommunication traffic Traffic control Sensor systems and applications Peer to peer computing Monitoring Large-scale systems distributed algorithms Sensor systems Protection

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Host Based Shared Multicast for Group Application

Host Based Shared Multicast for Group Application

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The 8th International Conference on Computer Supported Cooperative Work in Design(第八届计算机支持的协同工作设计国际会议)(CSCWD2004)

作者： Renjie Pi Xiaosu Zhan Junde Song Beijing University of Posts and Telecommunications

ISBN: (纸本)0780379411

The main idea in CSCW is that an application involvesmulti-person work as a group. They may lie in differentsites which are connected via network. When theapplication asks a real-time cooperation, an underlyingscheme should perform the necessary synchronization toensure the application semantics. We present adistributed algorithm which generates a share treecovering all group members. Each member only knows itslocal routing information. By the exchange of messagebetween members, the spanning tree is establishedcooperatively. When the transmit delay is not the crucialmetric for the application and each member have equalprobability to send data, the resulting overlay generatedby our method is optimal.

关键词： distributed algorithms groupware multicast communication trees (mathematics) message passing host based shared multicast group application CSCW multiperson work real-time cooperation synchronization application semantics distributed algorithm share tree local routing information message exchange spanning tree transmit delay

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Optimal uplink power control and base station assignment

Optimal uplink power control and base station assignment

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International Conference on Universal Personal Communications

作者： R. Yates C.Y. Huang ECE Department Winlab Rutgers University Piscataway NJ USA

In cellular wireless communication systems, transmitted power is regulated to provide each user an acceptable connection. Previous work has focused on maximizing the minimum carrier to interference ratio (CIR) or attaining a common CIR over all radio links. However, previous work has assumed the assignment of mobiles to base stations is known. In the context of a CDMA system, the authors combine power control and base station assignment. They consider the minimization of the total transmitted uplink power subject to maintaining an individual target CIR for each mobile. This minimization occurs over the set of power vectors and base station assignments. The authors identify distributed algorithms that find the optimal power vector and base station assignment.< >

关键词： Power control Base stations Iterative algorithms Radio transmitters Wireless communication Interference Multiaccess communication distributed algorithms Radio link Signal design

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