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Reliable distributed Systems

作者： Martin Byrenheid Stefanie Roos Thorsten Strufe TU Dresden Delft University of Technology

ISBN: (数字)9781728142227

ISBN: (纸本)9781728142234

Nodes in route-restricted overlays have an immutable set of neighbors, explicitly specified by their users. Popular examples include payment networks such as the Lightning network as well as social overlays such as the Dark Freenet. Routing algorithms are central to such overlays as they enable communication between nodes that are not directly connected. Recent results show that algorithms based on spanning trees are the most promising provably efficient choice. However, all suggested solutions fail to address how distributed spanning tree algorithms can deal with active denial of service attacks by malicious nodes. In this work, we design a novel self-stabilizing spanning tree construction algorithm that utilizes cryptographic signatures and prove that it reduces the set of nodes affected by active attacks. Our simulations substantiate this theoretical result with concrete values based on real-world data sets. In particular, our results indicate that our algorithm reduces the number of affected nodes by up to 74% compared to state-of-the-art attack-resistant spanning tree constructions.

关键词： computer network security cryptography digital signatures distributed algorithms overlay networks telecommunication network routing trees (mathematics) overlay network Network security digital signatures telecommunication network routing distributed algorithms cryptography Ganglia Spanning tree Overlay

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sSketch: A Scalable Sketching Technique for PCA in the Cloud 18

sSketch: A Scalable Sketching Technique for PCA in the Cloud

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11th ACM International Conference on Web Search and Data Mining

作者： Tanjim, Md. Mehrab Adnan, Muhammad Abdullah Bangladesh Univ Engn & Technol Dhaka Bangladesh

ISBN: (纸本)9781450355810

Multidimensional data appear frequently in many web-related applications, e.g., product ratings, the bag-of-words representation of web pages, etc. Principal Component Analysis (PCA) has been widely used for discovering patterns in relationships among entities in multidimensional data. However, existing algorithms for PCA have limited scalability since they explicitly materialize intermediate data, whose size rapidly grows as the dimension increases. To avoid scalability issues, we propose sSketch, a scalable sketching technique for PCA that employs several optimization ideas, such as mean propagation, efficient sparse matrix operations, and effective job consolidation to minimize intermediate data. Using sSketch, we also provide two other scalable methods for deriving singular value and 2-norm of reconstruction error, both of which are used for data analysis purpose. We provide our implementation on popular Spark framework for distributed platform. We compare our method against state-of-the-art library functions available for distributed settings, namely MLlib-PCA and Mahout-PCA with real big datasets. Our experiments show that our method outperforms both of them by a wide margin. To encourage reproducibility, the source code of sSketch is made publicly available at https://***/DataMiningResearch/sSketch.

关键词： big data data mining cloud computing machine learning distributed algorithms web-scale mining

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Sparse distributed Multitemporal Hyperspectral Unmixing

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2017年第11期55卷 6069-6084页

作者： Sigurdsson, Jakob Ulfarsson, Magnus O. Sveinsson, Johannes R. Bioucas-Dias, Jose M. Univ Iceland Dept Elect & Comp Engn IS-101 Reykjavik Iceland Univ Tecn Lisboa Inst Super Tecn P-1049001 Lisbon Portugal

Blind hyperspectral unmixing jointly estimates spectral signatures and abundances in hyperspectral images (HSIs). Hyperspectral unmixing is a powerful tool for analyzing hyperspectral data. However, the usual huge size of HSIs may raise difficulties for classical unmixing algorithms, namely, due to limitations of the hardware used. Therefore, some researchers have considered distributed algorithms. In this paper, we develop a distributed hyperspectral unmixing algorithm that uses the alternating direction method of multipliers and l(1) sparse regularization. The hyperspectral unmixing problem is split into a number of smaller subproblems that are individually solved, and then the solutions are combined. A key feature of the proposed algorithm is that each subproblem does not need to have access to the whole HSI. The algorithm may also be applied to multitemporal HSIs with due adaptations accounting for variability that often appears in multitemporal images. The effectiveness of the proposed algorithm is evaluated using both simulated data and real HSIs.

关键词： Alternating direction method of multipliers (ADMM) blind signal separation distributed algorithms feature extraction hyperspectral unmixing linear unmixing multitemporal unmixing

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Property Testing of Planarity in the CONGEST model 18

Property Testing of Planarity in the CONGEST model

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37th ACM SIGACT-SIGOPS Symposium on Principles of distributed Computing (PODC)

作者： Levi, Reut Medina, Moti Ron, Dana Weizmann Inst Sci Rehovot Israel Ben Gurion Univ Negev Beer Sheva Israel Tel Aviv Univ Tel Aviv Israel

ISBN: (纸本)9781450357951

We give a distributed algorithm in the CONGEST model for property testing of planarity with one-sided error in general (unbounded-degree) graphs. Following Censor-Hillel et al. (DISC 2016), who recently initiated the study of property testing in the distributed setting, our algorithm gives the following guarantee: For a graph G = (V,E) and a distance parameter., if G is planar, then every node outputs accept, and if G is.-far from being planar (i. e., more than epsilon center dot |E| edges need to be removed in order to make G planar), then with probability 1-1/poly(n) at least one node outputs reject. The algorithm runs in O(log |V| center dot poly(1/.)) rounds, and we show that this result is tight in terms of the dependence on |V|. Our algorithm combines several techniques of graph partitioning and local verification of planar embeddings. Furthermore, we show how a main subroutine in our algorithm can be applied to derive additional results for property testing of cycle-freeness and bipartiteness, as well as the construction of spanners, in minor-free (unweighted) graphs.

关键词： distributed algorithms Congest distributed property testing Planarity testing

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distributed Optimal Dispatch of distributed Energy Resources Over Lossy Communication Networks

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IEEE TRANSACTIONS ON SMART GRID 2017年第6期8卷 3125-3137页

作者： Wu, Junfeng Yang, Tao Wu, Di Kalsi, Karanjit Johansson, Karl Henrik Royal Inst Technol Sch Elect Engn ACCESS Linnaeus Ctr S-10044 Stockholm Sweden Univ North Texas Dept Elect Engn Denton TX 75203 USA Pacific Northwest Natl Lab Richland WA 99352 USA

Driven by smart grid technologies, a great effort has been made in developing distributed energy resources (DERs) in recent years for improving reliability and efficiency of distribution systems. Emerging DERs require effective and efficient control and coordination in order to harvest their potential benefits. In this paper, we consider optimal DER coordination problem, where the goal is to minimize the total generation cost while meeting total demand and satisfying individual generator output limit. This paper develops a distributed algorithm for solving the optimal DER coordination problem over lossy communication networks with packet-dropping communication links. Under the assumption that the underlying communication network is strongly connected with a positive probability and the packet drops are independent and identically distributed, we show that the proposed algorithm is able to solve the optimal DER coordination problem even in the presence of packet drops. Numerical simulation results are used to validate and illustrate the proposed algorithm.

关键词： distributed algorithms optimal DER coordination packet drops power systems smart grids

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A distributed Frequency Regulation Architecture for Islanded Inertialess AC Microgrids

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IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY 2017年第6期25卷 1961-1977页

作者： Cady, Stanton T. Zholbaryssov, Madi Dominguez-Garcia, Alejandro D. Hadjicostis, Christoforos N. Univ Illinois Dept Elect & Comp Engn Urbana IL 61801 USA Univ Cyprus Dept Elect & Comp Engn CY-1678 Nicosia Cyprus

We address the problem of frequency regulation in islanded ac microgrids with no inertia, i.e., those consisting entirely of generators interfaced through power electronics. The control architecture we propose to achieve this is designed to drive the average frequency error to zero while ensuring that the frequency at every bus is equal and that the operating point that results is stable. We also introduce a distributed implementation of the proposed control architecture that relies on a combination of three distributed algorithms. Two of the algorithms, which are well-established consensus-type algorithms, allow the generators and loads to acquire global information needed for making control decisions;the third algorithm, which we propose herein, enables the generators to obtain output values that balance the total demand for load without violating line flow constraints. Collectively, these algorithms eliminate the need for a centralized entity with complete knowledge of the network, its topology, or the capabilities or properties of the generators and loads therein. Moreover, the distributed implementation we propose relies on minimal measurements, requiring only that the power injection at each bus be measured. To verify our proposed control architecture and the algorithms on which its distributed implementation relies, we analytically show that the resulting closed-loop system is stable and establish convergence of our proposed algorithm. We also illustrate the features of the architecture using numerical simulations of three test cases applied to 6-and 37-bus networks.

关键词： distributed power generation distributed algorithms microgrids networked control systems network theory (graphs).

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Parallel Processing of Very Large Databases Using distributed Column Indexes

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PROGRAMMING AND COMPUTER SOFTWARE 2017年第3期43卷 131-144页

作者： Ivanova, E. V. Sokolinsky, L. B. South Ural State Univ Chelyabinsk 454080 Russia

The development and investigation of efficient methods of parallel processing of very large databases using the columnar data representation designed for computer cluster is discussed. An approach that combines the advantages of relational and column-oriented DBMSs is proposed. A new type of distributed column indexes fragmented based on the domain-interval principle is introduced. The column indexes are auxiliary structures that are constantly stored in the distributed main memory of a computer cluster. To match the elements of a column index to the tuples of the original relation, surrogate keys are used. Resource hungry relational operations are performed on the corresponding column indexes rather than on the original relations of the database. As a result, a precomputation table is obtained. Using this table, the DBMS reconstructs the resulting relation. For basic relational operations on column indexes, methods for their parallel decomposition that do not require massive data exchanges between the processor nodes are proposed. This approach improves the class OLAP query performance by hundreds of times.

关键词： PARALLEL processing (Electronic computers) DATABASES distributed algorithms INDEXES DATA transmission systems

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distributed control scheme on cost optimisation under communication delays for DC microgrids

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IET GENERATION TRANSMISSION & DISTRIBUTION 2017年第17期11卷 4193-4201页

作者： Han, Hua Wang, Hao Sun, Yao Yang, Jian Liu, Zhangjie Cent S Univ Dept Informat Sci & Engn Minzhu Bldg Changsha Hunan Peoples R China

This study addresses the distributed economic dispatch problem for DC microgrids when time-varying delays are present in communication networks. A novel distributed algorithm is proposed, and the proposed controller contains a distributed generation cost optimisation module and a voltage regulation module. The cost optimisation module is aimed to realise cost optimisation by driving the incremental cost rate of every distributed generator to be equal. In the voltage regulation module, a distributed synchronisation algorithm is used to restore the global average voltage. After the effect of the communication delay on the system stability is analysed, the robust stability criticality under load changes is obtained by using linear matrix inequality. The performance of the proposed scheme is validated through simulations and experimentally.

关键词： power generation economics distributed control power generation dispatch optimisation voltage control power system stability robust control delay systems time-varying systems distributed algorithms synchronisation power system restoration distributed power generation distributed control communication delays DC microgrids distributed economic dispatch problem time-varying delays communication networks distributed generation cost optimisation module voltage regulation module incremental cost rate distributed synchronisation algorithm global average voltage restoration system stability robust stability criticality load changes linear matrix inequality

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Deterministic Dispersion of Mobile Robots in Dynamic Rings 18

Deterministic Dispersion of Mobile Robots in Dynamic Rings

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19th International Conference on distributed Computing and Networking (ICDCN)

作者： Agarwalla, Ankush Augustine, John Moses, William K., Jr. Sankar, Madhav K. Sridhar, Arvind Krishna Natl Inst Technol Rourkela Dept Comp Sci & Engn Rourkela Odisha India Indian Inst Technol Madras Dept Comp Sci & Engn Chennai Tamil Nadu India Natl Inst Technol Tiruchirappalli Dept Comp Sci & Engn Tiruchirappalli Tamil Nadu India

ISBN: (纸本)9781450363723

In this work, we study the problem of dispersion of mobile robots on dynamic rings. The problem of dispersion of n robots on an n node graph, introduced by Augustine and Moses Jr. [2], requires robots to coordinate with each other and reach a configuration where exactly one robot is present on each node. This problem has real world applications and applies whenever we want to minimize the total cost of n agents sharing n resources, located at various places, subject to the constraint that cost of an agent moving to a different resource is comparatively much smaller than cost of multiple agents sharing a resource (e.g. smart electric cars sharing recharge stations). Study of this problem also provides indirect benefits to the studies of scattering on graphs, exploration by mobile robots, and load balancing on graphs. We solve the problem of dispersion in presence of two types of dynamism in the underlying graph: (i) vertex permutation and (ii) 1-interval connectivity. We introduce the notion of vertex permutation dynamism and have it mean that for a given set of nodes, in every round, the adversary ensures a ring structure is maintained, but the connections between the nodes may change. We use the idea of 1-interval connectivity from Di Luna et al. [11], where for a given ring, in each round, the adversary chooses at most one edge to remove. We assume robots have full visibility and present asymptotically time optimal algorithms to achieve dispersion in the presence of both types of dynamism when robots have chirality. When robots do not have chirality, we present asymptotically time optimal algorithms to achieve dispersion subject to certain constraints. Finally, we provide impossibility results for dispersion when robots have no visibility.

关键词： Dispersion Load balancing Mobile robots Collective robot exploration Scattering Dynamic graph algorithms Dynamic networks Deterministic algorithms distributed algorithms

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Differentially Private distributed Constrained Optimization

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 2017年第1期62卷 50-64页

作者： Han, Shuo Topcu, Ufuk Pappas, George J. Univ Pennsylvania Dept Elect & Syst Engn Philadelphia PA 19104 USA Univ Texas Austin Dept Aerosp Engn & Engn Mech Austin TX 78712 USA

Many resource allocation problems can be formulated as an optimization problem whose constraints contain sensitive information about participating users. This paper concerns a class of resource allocation problems whose objective function depends on the aggregate allocation ( i.e., the sum of individual allocations);in particular, we investigate distributed algorithmic solutions that preserve the privacy of participating users. Without privacy considerations, existing distributed algorithms normally consist of a central entity computing and broadcasting certain public coordination signals to participating users. However, the coordination signals often depend on user information, so that an adversary who has access to the coordination signals can potentially decode information on individual users and put user privacy at risk. We present a distributed optimization algorithm that preserves differential privacy, which is a strong notion that guarantees user privacy regardless of any auxiliary information an adversary may have. The algorithm achieves privacy by perturbing the public signals with additive noise, whose magnitude is determined by the sensitivity of the projection operation onto user-specified constraints. By viewing the differentially private algorithm as an implementation of stochastic gradient descent, we are able to derive a bound for the suboptimality of the algorithm. We illustrate the implementation of our algorithm via a case study of electric vehicle charging. Specifically, we derive the sensitivity and present numerical simulations for the algorithm. Through numerical simulations, we are able to investigate various aspects of the algorithm when being used in practice, including the choice of step size, number of iterations, and the trade-off between privacy level and suboptimality.

关键词： Data privacy distributed algorithms optimizationm methods

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