检索结果-内蒙古大学图书馆

Analysis and Design of a Novel randomized Broadcast algorithm for Scalable Wireless Networks in the Interference Channels

引用

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2010年第7期9卷 2206-2215页

作者： Huang, Scott C. -H. Chang, Shih Yu Wu, Hsiao-Chun Wan, Peng-Jun City Univ Hong Kong Dept Comp Sci Kowloon Hong Kong Peoples R China Louisiana State Univ Dept Elect & Comp Engn Baton Rouge LA 70803 USA Natl Tsing Hua Univ Dept Comp Sci Hsinchu Taiwan IIT Dept Comp Sci Chicago IL 60616 USA

In this paper, we study the minimum-latency broadcast scheduling problem in the probabilistic model. We establish an explicit relationship between the tolerated transmission-failure probability and the latency of the corresponding broadcast schedule. Such a tolerated transmission-failure probability is calculated in the strict sense that the failure to receive the message at any single node will lead to the entire broadcast failure and only if all nodes have successfully received the message do we consider it a success. We design a novel broadcast scheduling algorithm such that the broadcast latency is evaluated under such a strict definition of failure. The latency bound we derive is a strong result in the sense that our algorithm achieves a low broadcast latency under this rather strict broadcast-failure definition. Simulation results are also provided to justify our derived theoretical latency bound.

关键词： Wireless networks scheduling randomized algorithm

来源：评论

学校读者我要写书评

暂无评论

Estimation of horizontal and vertical translations of large images based on columns and rows mean energy matching

引用

MULTIDIMENSIONAL SYSTEMS AND SIGNAL PROCESSING 2014年第2期25卷 273-294页

作者： Skubalska-Rafajlowicz, Ewa Wroclaw Univ Technol Inst Comp Engn Automat & Robot PL-50370 Wroclaw Poland

In this paper mean energy lateral histograms have been developed and used for the translation of frames detection and for the estimation of a shift vector in large image frames. 2-D translation problem is solved by two almost independent 1-D problems based on the mean energy lateral histograms. We formulate a simple optimization for estimating vertical or horizontal translations of the frame. The optimization goal is to find the best match between energies (squared norms) of rows (columns) of the image and the reference frame. The shift estimate is calculated as the minimizer of the least squares, maximum deviation or the sum of absolute deviations criterion. However, the first criterion is preferred, the last two almost always gave the same results when the noise level is low. The proposed method is faster than the FFT based phase-correlation approach. An iterative version of the algorithm is presented which is very reliable and usually converges in at most two iterations. A randomized version of the method which reduce further the computational cost for large images problems is also proposed. Experimental results are provided and discussed.

关键词： Image stabilization Shift estimation randomized algorithm Lateral energy histograms

来源：评论

学校读者我要写书评

暂无评论

Xheal: a localized self-healing algorithm using expanders

引用

DISTRIBUTED COMPUTING 2014年第1期27卷 39-54页

作者： Pandurangan, Gopal Trehan, Amitabh Nanyang Technol Univ Div Math Sci Singapore 637371 Singapore Brown Univ Dept Comp Sci Providence RI 02912 USA Technion Israel Inst Technol Fac Ind Engn & Management IL-32000 Haifa Israel

We consider the problem of self-healing in reconfigurable networks e.g., peer-to-peer and wireless mesh networks. For such networks under repeated attack by an omniscient adversary, we propose a fully distributed algorithm, Xheal, that maintains good expansion and spectral properties of the network, while keeping the network connected. Moreover, Xheal does this while allowing only low stretch and degree increase per node. The algorithm heals global properties like expansion and stretch while only doing local changes and using only local information. We also provide bounds on the second smallest eigenvalue of the Laplacian which captures key properties such as mixing time, conductance, congestion in routing etc. Xheal has low amortized latency and bandwidth requirements. Our work improves over the self-healing algorithms Forgiving tree [PODC 2008] and Forgiving graph [PODC 2009] in that we are able to give guarantees on degree and stretch, while at the same time preserving the expansion and spectral properties of the network.

关键词： Self-healing Reconfigurable networks Peer-to-peer Local versus global Expansion Spectral properties Distributed algorithm randomized algorithm

来源：评论

学校读者我要写书评

暂无评论

LSRN: A PARALLEL ITERATIVE SOLVER FOR STRONGLY OVER- OR UNDERDETERMINED SYSTEMS

引用

SIAM JOURNAL ON SCIENTIFIC COMPUTING 2014年第2期36卷 C95-C118页

作者： Meng, Xiangrui Saunders, Michael A. Mahoney, Michael W. Stanford Univ ICME Stanford CA 94305 USA Stanford Univ Dept Management Sci & Engn Syst Optimizat Lab Stanford CA 94305 USA Stanford Univ Dept Math Stanford CA 94305 USA

We describe a parallel iterative least squares solver named LSRN that is based on random normal projection. LSRN computes the min-length solution to min(x is an element of Rn) vertical bar vertical bar Ax - b vertical bar vertical bar(2), where A is an element of R-mxn with m >> n or m << n, and where A may be rank-deficient. Tikhonov regularization may also be included. Since A is involved only in matrix-matrix and matrix-vector multiplications, it can be a dense or sparse matrix or a linear operator, and LSRN automatically speeds up when A is sparse or a fast linear operator. The preconditioning phase consists of a random normal projection, which is embarrassingly parallel, and a singular value decomposition of size inverted right perpendicular gamma min(m, n) inverted left perpendicular x min(m, n), where gamma is moderately larger than 1, e.g., gamma = 2. We prove that the preconditioned system is well-conditioned, with a strong concentration result on the extreme singular values, and hence that the number of iterations is fully predictable when we apply LSQR or the Chebyshev semi-iterative method. As we demonstrate, the Chebyshev method is particularly efficient for solving large problems on clusters with high communication cost. Numerical results show that on a shared-memory machine, LSRN is very competitive with LAPACK's DGELSD and a fast randomized least squares solver called Blendenpik on large dense problems, and it outperforms the least squares solver from SuiteSparseQR on sparse problems without sparsity patterns that can be exploited to reduce fill-in. Further experiments show that LSRN scales well on an Amazon Elastic Compute Cloud cluster.

关键词： linear least squares overdetermined system underdetermined system rank-deficient minimum-length solution LAPACK sparse matrix iterative method preconditioning LSQR Chebyshev semi-iterative method Tikhonov regularization ridge regression parallel computing random projection random sampling random matrix randomized algorithm

来源：评论

学校读者我要写书评

暂无评论

Mathematical modeling of group product recommendation with partial information: How many ratings do we need?

引用

PERFORMANCE EVALUATION 2014年第Jul.期77卷 72-95页

作者： Xie, Hong Lui, John C. S. Chinese Univ Hong Kong Dept Comp Sci & Engn Hong Kong Hong Kong Peoples R China

Product recommendation is one of the most important services in the Internet. In this paper, we consider a product recommendation system which recommends products to a group of users. The recommendation system only has partial preference information on this group of users: a user only indicates his preference to a small subset of products in the form of ratings. This partial preference information makes it a challenge to produce an accurate recommendation. In this work, we explore a number of fundamental questions. What is the desired number of ratings per product so to guarantee an accurate recommendation? What are some effective voting rules in summarizing ratings? How users' misbehavior such as cheating, in product rating may affect the recommendation accuracy? What are some efficient rating schemes? To answer these questions, we present a formal mathematical model of a group recommendation system. We formally analyze the model. Through this analysis we gain the insight to develop a randomized algorithm which is both computationally efficient and asymptotically accurate in evaluating the recommendation accuracy under a very general setting. We propose a novel and efficient heterogeneous rating scheme which requires equal or less rating workload, but can improve over a homogeneous rating scheme by as much as 30%. We carry out experiments on both synthetic data and real-world data from TripAdvisor. Not only we validate our model, but also we obtain a number of interesting observations, i.e., a small of misbehaving users can decrease the recommendation accuracy remarkably. For TripAdvisor, one hundred ratings per product is sufficient to guarantee a high accuracy recommendation. We believe our model and methodology are important building blocks to refine and improve applications of group recommendation systems. (C) 2014 Published by Elsevier B.V.

关键词： Group recommendation systems Partial preference information randomized algorithm Performance evaluation

来源：评论

学校读者我要写书评

暂无评论

Distributed (Δ+1)-coloring in the physical model

引用

THEORETICAL COMPUTER SCIENCE 2014年第0期553卷 37-56页

作者： Yu, Dongxiao Wang, Yuexuan Hua, Qiang-Sheng Lau, Francis C. M. Univ Hong Kong Dept Comp Sci Hong Kong Hong Kong Peoples R China Tsinghua Univ Inst Interdisciplinary Informat Sci Beijing 100084 Peoples R China

In multi-hop radio networks, such as wireless ad-hoc networks and wireless sensor networks, nodes employ a MAC (Medium Access Control) protocol such as TDMA to coordinate accesses to the shared medium and to avoid interference of close-by transmissions. These protocols can be implemented using standard node coloring. The (Delta + 1)-coloring problem is to color all nodes in as few timeslots as possible using at most Delta + 1 colors such that any two nodes within distance R are assigned different colors, where R is a given parameter and Delta is the maximum degree of the modeled unit disk graph using R as a scaling factor. Being one of the most fundamental problems in distributed computing, this problem is well studied and there is a long chain of algorithms prescribed for it. However, all previous works are based on abstract models, such as message passing models and graph based interference models, which limit the utility of these algorithms in practice. In this paper, for the first time, we consider the distributed (Delta + 1)-coloring problem under the more practical SINR interference model. In particular, without requiring any knowledge about the neighborhood, we propose a novel randomized (Delta + 1)-coloring algorithm with time complexity O (Delta log n + log(2) n). For the case where nodes cannot adjust their transmission power, we give an O (Delta log(2) n) randomized algorithm, which only incurs a logarithmic multiplicative factor overhead. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Distributed algorithm randomized algorithm Wireless ad-hoc and sensor networks Coloring Physical interference model

来源：评论

学校读者我要写书评

暂无评论

Complexity insights of the MINIMUM DUPLICATION problem

引用

THEORETICAL COMPUTER SCIENCE 2014年 530卷 66-79页

作者： Blin, Guillaume Bonizzoni, Paola Dondi, Riccardo Rizzi, Romeo Sikora, Florian Univ Paris Est LIGM UMR 8049 Paris France Univ Milano Bicocca DISCo Milan Italy Univ Bergamo Dipartimento Sci Umane & Sociali Bergamo Italy Univ Verona Dept Comp Sci I-37100 Verona Italy Univ Paris 09 PSL LAMSADE UMR 7243 Paris France

The MINIMUM DUPLICATION problem is a well-known problem in phylogenetics and comparative genomics. Given a set of gene trees, the MINIMUM DUPLICATION problem asks for a species tree that induces the minimum number of gene duplications in the input gene trees. Recently, a variant of the MINIMUM DUPLICATION problem, called MINIMUM DUPLICATION BIPARTITE, has been introduced, where the goal is to find all pre-duplications, that is duplications that in the evolution precede the first speciation with respect to a species tree. In this paper, we investigate the complexity of both MINIMUM DUPLICATION and MINIMUM DUPLICATION BIPARTITE. First of all, we prove that the MINIMUM DUPLICATION problem is APX-hard, even when the input consists of five uniquely leaf-labeled gene trees (improving upon known results on the complexity of the problem). Then, we show that the MINIMUM DUPLICATION BIPARTITE problem can be solved efficiently with a randomized algorithm when the input gene trees have bounded depth. An extended abstract of this paper appeared in SOFSEM 2012 [1]. (c) 2014 Elsevier B.V. All rights reserved.

关键词： Minimum Duplication problem Comparative genomics Computational complexity APX-hardness randomized algorithm

来源：评论

学校读者我要写书评

暂无评论

Analysis of Distributed Token Circulation algorithm with Faulty Random Number Generator

引用

PARALLEL PROCESSING LETTERS 2014年第1期24卷 1450002-1-1450002-15页

作者： Kawai, Shinji Ooshita, Fukuhito Kakugawa, Hirotsugu Masuzawa, Toshimitsu Osaka Univ Grad Sch Informat Sci & Technol 1-5 Yamadaoka Suita Osaka 5650871 Japan

Randomization is a technique to improve efficiency and computability of distributed computing. In this paper, we investigate fault tolerance of distributed computing against faults of random number generators. We introduce an RNG (Random Number Generator)-fault as a new class of faults;a random number generator on an RNG-faulty process outputs the same number deterministically. This paper is the first work that considers faults of randomness in distributed computing. We investigate the role of randomization by observing the impact of RNG-faults on performance of a self-stabilizing token circulation algorithm on unidirectional n-node ring networks [11. In the analysis, we assume there exist nf (0 <= n(f) <= n 1) RNG-faulty nodes and each RNG-faulty node always transfers a token to the next node. Our results are threefold: (1) We derive the upper bound on the expected convergence time in the case of n(f) = n - 1. (2) Our simulation result shows that the expected convergence time is maximum when n(f) = n - 1. (3) We derive the expected token circulation time for each nf (0 <= n(f) <= n 1).

关键词： Distributed system self-stabilization token circulation algorithm randomized algorithm RNG-fault

来源：评论

学校读者我要写书评

暂无评论

A Monte Carlo algorithm for real time task scheduling on multi-core processors with software controlled dynamic voltage scaling

引用

APPLIED MATHEMATICAL MODELLING 2014年第7-8期38卷 1929-1947页

作者： Mishra, Abhishek Tripathi, Anil Kumar Indian Inst Technol Jodhpur Ctr Excellence Informat & Commun Technol Jodhpur 342011 Rajasthan India Banaras Hindu Univ Indian Inst Technol Dept Comp Engn Varanasi 221005 Uttar Pradesh India

The task scheduling problem for multi-core processors is an important algorithm design issue. Dynamic voltage scaling (DVS) is used to reduce the energy consumption of cores. We ponder the problem of task scheduling on a multi-core processor with software controlled DVS where the objective is to reduce the energy consumption. We consider a system with a single multi-core processor with software controlled DVS having a finite set of core speeds and discuss a task scheduling problem associated with it. The problem that we address is to find a minimum energy task schedule for a given set of independent tasks that have to be completed within a given common deadline. We propose a Monte Carlo algorithm of complexity O(t(mp + q + log(t)) + p(t + q)(D-pq + n)) for solving the task scheduling problem and compare it with the optimal algorithm. Here t is the number of tasks, p is the number of cores, q is the number of core speeds, m is an integer parameter that is the number of iterations we should try to get a feasible solution before declaring that no solution is possible, n is an integer parameter that is the number of iterations we should try to reduce the energy consumption when we get a feasible solution, and D is the common deadline of the tasks. (C) 2013 Elsevier Inc. All rights reserved.

关键词： Dynamic voltage scaling Energy efficient scheduling Multi-core processor randomized algorithm

来源：评论

学校读者我要写书评

暂无评论

A new approach to address Subset Sum Problem 5

A new approach to address Subset Sum Problem

引用

5th International Conference on Confluence - The Next Generation Information Technology Summit (Confluence)

作者： Jain, Eeti Jain, Akarsh Mankad, Sapan H. Nirma Univ Inst Technol CSE Dept Ahmadabad Gujarat India

ISBN: (纸本)9781479942367

In this paper, Subset Sum problem (Non Polynomial Complete problem) and analysis of its two solutions is discussed. These solutions are the Dynamic Solution algorithm and the randomized algorithm. Dynamic Solution is a sound and complete algorithm that can be used to determine satisfiability and unsatisfiability with certainty. randomized algorithm can determine satisfiablity as well as the solution if it finds a solution, but it cannot guarantee to find a solution even if there exists one. However, randomized algorithm is much faster than iterative algorithm and also finds the solution, which makes it more practical. In addition, analogy between these two algorithms and two other algorithms namely PL-Resolution and Walk-Sat algorithms for 3-CNF SAT problem, which is also NPC problem is discussed and the performance of randomized algorithm and WalkSAT algorithm is acceptable if the problem is not so complex.

关键词： Subset Sum NPC Problem Dynamic Solution randomized algorithm PL-Resolution Walk-SAT algorithm

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：