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Revisiting the Expansion Length of Triple-base Number System for Elliptic Curve Scalar Multiplication

JOURNAL OF INFORMATION SCIENCE AND ENGINEERING 2018年第3期34卷 721-732页

作者： Dou, Yun-Qi Weng, Jiang Ma, Chuan-Gui Wei, Fu-Shan State Key Lab Math Engn & Adv Comp Zhengzhou 450001 Henan Peoples R China State Key Lab Cryptol Beijing 100878 Peoples R China Air Force Engn Univ Informat & Nav Coll Xian 710077 Shaanxi Peoples R China Army Aviat Inst Dept Basic Beijing 101123 Peoples R China

Because of its sparsity, triple-base number system is used to accelerate the scalar multiplication in elliptic curve cryptography. Yu et al. presented an estimate for the length of triple-base number system at Africacrypt 2013. However, the efficiency of scalar multiplication is not only associated with the length of representation but also the numbers and costs of doubling, tripling, quintupling and addition. It is necessary to set a restriction for exponents of base 2, 3 and 5, which will lead to longer expansion length. In this situation, we prove a stronger result: the upper bound on expansion length of constrained triple-base number system is still sub-linear. This result provides more practical boundary of the triple-base number system to speed up the scalar multiplication. At the same time, it also generalizes the result of Meloni et al. about double-base number system.

关键词： elliptic curve cryptography scalar multiplication constrained triple-base number system greedy algorithm sub-linear

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Multi-Objective Optimal Sensor Placement for Low-Pressure Gas Distribution Networks

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IEEE SENSORS JOURNAL 2018年第16期18卷 6660-6668页

作者： Zan, Thaw Tar Thein Gupta, Payal Wang, Mengmeng Dauwels, Justin Ukil, Abhisek Nanyang Technol Univ ERIAN Energy Res Inst Singapore 639798 Singapore Digital Money Myanmar Yangon Myanmar Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore Univ Auckland Dept Elect & Comp Engn Auckland 1010 New Zealand

Natural gas distribution systems are inherently vulnerable to accidental or intentional intrusion. Such events lead to financial losses and endanger the environmental and public safety. Therefore, it is crucial to adequately monitor the gas distribution systems. An important step toward this goal is to optimize the placement of sensors in the network. In this paper, we propose three design objectives including time-to-detection (TTD), sensitivity, and impact propagation (IP) and implement five multi-objective optimization algorithms (greedy, greedy randomized adaptive search procedure, non-dominated sorting genetic algorithm II, FrameSense, and particle swarm optimization (PSO)) to strategically place the sensors. From the results on an artificial network with 37 nodes and 50 branches and a real network in Singapore with 148 nodes and 150 branches, we find that greedy and PSO algorithms are almost 10 times faster than the other algorithms in computational time. We also investigate the tradeoff between the design objectives and the number of sensors. Since TTD, sensitivity, and IP have different measurement units, we normalize their values within 0 to 1 (0%-100%) and consider the average of those three normalized values as the design cost. For 10% design cost, the number of required sensors is 5 and 8 for the artificial network and the real network, respectively. The results indicate that PSO yields the sensor configuration with the lowest design cost and the computational time.

关键词： Sensor placement multi-objective optimization FrameSense genetic algorithm GRASP greedy algorithm particle swarm optimization algorithm

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Simple Approximation algorithms for Balanced MAX 2SAT

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algorithmICA 2018年第3期80卷 995-1012页

作者： Paul, Alice Poloczek, Matthias Williamson, David P. Cornell Univ Sch Operat Res & Informat Engn Ithaca NY 14850 USA

We study simple algorithms for the balanced MAX 2SAT problem, where we are given weighted clauses of length one and two with the property that for each variable x the total weight of clauses that x appears in equals the total weight of clauses for . We show that such instances have a simple structural property in that any optimal solution can satisfy at most the total weight of the clauses minus half the total weight of the unit clauses. Using this property and a novel analysis of the computation tree, we are able to show that a large class of greedy algorithms, including Johnson's algorithm, gives a -approximation algorithm for balanced MAX 2SAT;a similar statement is false for general MAX 2SAT instances. We further give a spectral 0.81-approximation algorithm for balanced MAX E2SAT instances (in which each clause has exactly 2 literals) by a reduction to a spectral algorithm of Trevisan for the maximum colored cut problem. We provide experimental results showing that this spectral algorithm performs well and is slightly better than Johnson's algorithm and the Goemans-Williamson semidefinite programming algorithm on balanced MAX E2SAT instances.

关键词： Maximum satisfiability Approximation algorithm greedy algorithm Spectral algorithm Balanced instances Priority algorithm

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Pilot contamination reduction in massive MIMO systems based on pilot scheduling

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EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2018年第1期2018卷 21-21页

作者： Wu, Yucheng Liu, Tong Cao, Meng Li, Liang Xu, Weiyang Chongqing Univ Coll Commun Engn 174 Shazhengjie Chongqing Peoples R China

The pilot contamination caused by sharing the non-orthogonal pilots among users is considered to be a bottleneck of the massive multi-input multi-output (MIMO) systems. This paper proposes a pilot scheduling scheme based on the degradation to address this problem. Through computing the degradation of the users, the proposed scheduling assigns the optimal pilot sequence to the user who suffers from the greatest degradation in a greedy way. Moreover, the proposed scheme is further optimized with an extra set of orthogonal pilot sequences, which is called pilot scheduling scheme based on user grouping. Simulation results show that the target cell's achievable sum rate of the proposed scheme is much higher than the random pilot scheduling (RPS) and the smart pilot assignment (SPA) schemes;also, our scheme can reduce the impact of shadowing fading on the target cell's achievable sum rate effectively.

关键词： Massive MIMO Pilot contamination Pilot scheduling greedy algorithm User grouping

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Does fragmentation avoidance improve the performance of dynamic spectrum allocation in elastic optical networks?

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PHOTONIC NETWORK COMMUNICATIONS 2018年第3期35卷 287-299页

作者： Borquez-Paredes, Danilo Beghelli, Alejandra Leiva, Ariel Murrugarra, Ruth Univ Adolfo Ibanez Fac Engn & Sci Campus Vina del Mar Vina Del Mar Chile Pontificia Univ Catolica Valparaiso Sch Elect Engn Valparaiso Chile

Most spectrum allocation algorithms in elastic optical networks apply a greedy approach: A new connection is allocated as long as there are enough spectrum slots to accommodate it. Recently, a different approach was proposed. Named Deadlock-Avoidance (DA), it only establishes a new connection if the portion of spectrum left after allocating it is zero (full-link utilization) or is big enough to accommodate future requests. Otherwise, the connection request is blocked as a way to avoid fragmentation. The performance of DA has been evaluated in a single-link scenario, where its performance is not affected by the slot continuity constraint. In this paper, we evaluate for the first time the blocking performance and fragmentation level of DA in a fully dynamic network scenario with different bitrates and number of slots for a single link, a 4-node bus and a mesh topology. The performance was evaluated by simulation, and a lower bound was also derived using a continuous Markov chain model. Results are obtained for DA and three greedy algorithms: First Fit, Exact Fit and First-Last Fit. Results show that DA significantly decreases fragmentation, and thus, it exhibits a much lower blocking due to fragmentation than the greedy algorithms. However, this decrease is compensated by a new type of blocking due to the selective acceptance of connections. As a result, the extra computational complexity of DA does not compensate a gain in performance.

关键词： Flexible grid optical networks greedy algorithm Deadlock avoidance Fragmentation

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Multiscale model reduction for fluid infiltration simulation through dual-continuum porous media with localized uncertainties

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JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 2018年 336卷 127-146页

作者： Li, Qiuqi Wang, Yuhe Vasilyeva, Maria Hunan Univ Coll Math & Econometr Changsha 410082 Hunan Peoples R China Texas A&M Univ Qatar Dept Petr Engn Doha Qatar Texas A&M Univ Inst Sci Computat College Stn TX 77843 USA North Eastern Fed Univ Dept Computat Technol Yakutsk Russia

Here, we present some Reduced Basis (RB) methods for fluid infiltration problems through certain porous media modeled as dual-continuum with localized uncertainties. We apply dimension reduction techniques to construct a reduced order model. In the RB methods, to perform the offline online computation decomposition, the model inputs need to be affinely dependent on the uncertainties. We develop a Proper Orthogonal Decomposition and greedy (POD-greedy) RB method for stochastic dual-continuum models. In the POD greedy RB framework, for heterogeneous porous media, we need to solve the stochastic dual-continuum models many times using very fine grid to construct a set of snapshots for building optimal reduced basis. This offline computation may be very expensive. To improve the offline computational efficiency, we further develop a local global RB method, which integrates the coupled multiscale and multicontinuum approach using Generalized Multiscale Finite Element Method (GMsFEM) to the POD-greedy RB method. To illustrate the efficiency of the proposed methods, we present two numerical examples for stochastic dual-continuum models. Our numerical results show that both the POD-greedy RB method and the local global RB method greatly improve the computation efficiency with high approximation accuracy. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Reduced basis methods GMsFEM Local-global RB method greedy algorithm Proper orthogonal decomposition Stochastic Dual-continuum model

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Toward a real-time and budget-aware task package allocation in spatial crowdsourcing

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DECISION SUPPORT SYSTEMS 2018年 110卷 107-117页

作者： Wu, Pengkun Ngai, Eric W. T. Wu, Yuanyuan Harbin Inst Technol Sch Management Harbin Heilongjiang Peoples R China Hong Kong Polytech Univ Dept Management & Mkt Hong Kong Hong Kong Peoples R China

With the development of mobile technology, spatial crowdsourcing has become a popular approach in collecting data or road information. However, as the number of spatial crowdsourcing tasks becomes increasingly large, the accurate and rapid allocation of tasks to suitable workers has become a major challenge in managing spatial outsourcing. Existing studies have explored the task allocation algorithms with the aim of guaranteeing quality information from workers. However, studies focusing on the task allocation rate when allocating tasks are still lacking despite the increasing unallocated rates of spatial crowdsourcing tasks in the real world. Although the task package is a commonly known scheme used to allocate tasks, it has not been applied to allocate spatial crowdsourcing tasks. To fill these gaps in the literature, we propose a real-time, budget-aware task package allocation for spatial crowdsourcing (RB-TPSC) with the dual objectives of improving the task allocation rate and maximizing the expected quality of results from workers under limited budgets. The proposed RB-TPSC enables spatial crowdsourcing task requester to automatically make key task allocation decisions on the following: (1) to whom should the task be allocated, (2) how much should the reward be for the task, and (3) whether and how the task is packaged with other tasks.

关键词： Spatial crowdsourcing Task allocation algorithm Task package Incentive mechanism greedy algorithm Reputation

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PULLPRU: a practical approach to estimate phylogenies from single nucleotide polymorphism haplotypes under the maximum parsimony criterion

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COMPUTATIONAL & APPLIED MATHEMATICS 2018年第5期37卷 5681-5701页

作者： Feizabadi, R. Bagherian, M. Vaziri, H. R. Salahi, M. Univ Guilan Fac Math Sci Dept Appl Math Rasht Iran Univ Guilan Fac Sci Dept Biol Rasht Iran

Phylogeny estimation has been the subject of several researches due to its significant importance and numerous applications. The aim of this research is to study the phylogeny estimation from Single Nucleotide Polymorphism (SNP) haplotypes under the maximum parsimony criterion (MPPEP-SNP). Previous exact methods have modeled the mentioned problem as a Mixed Integer Programming (MIP) problem. Since the problem, in general, proved to be NP-hard which causes MIP models to take long runtime for solving large-scale instances, the need for non-exact methods is obvious. In this paper, the authors propose a heuristic algorithm that attempts to find the MPPEP-SNP solution in several stages by solving a specific MIP model in each stage. Created based on network flows formulation, MIP models appearing in each stage are very small;therefore, their exact solutions could be found practically very fast. In order to evaluate the performance of the proposed algorithm, it has been tested on both simulated and real instances and compared with Pars and Flow-RM as two of the best known methods. Our numerical experiments show that the proposed method can compete with the previous methods in terms of accuracy, runtime, and specially the largeness of the solved instances.

关键词： Phylogeny estimation Haplotype Maximum parsimony Computational biology greedy algorithm Graph Network flows Mixed integer programming 90C11 90C35 90C90

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An analysis of shipyard spatial arrangement planning problems and a spatial arrangement algorithm considering free space and unplaced block

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2018年第9-12期95卷 4307-4325页

作者： Jeong, Yong-Kuk Ju, SuHeon Shen, Huiqiang Lee, Dong Kun Shin, Jong Gye Ryu, Cheolho Seoul Natl Univ Dept Naval Architecture & Ocean Engn Seoul 08826 South Korea Mokpo Natl Maritime Univ Dept Naval Architecture & Ocean Engn Mokpo 58628 South Korea Seoul Natl Univ Res Inst Marine Syst Engn Seoul 08826 South Korea Inha Tech Coll Dept Naval Architecture & Ocean Engn Incheon 22212 South Korea

The components of shipyard production systems can be classified into products, processes, facilities, space, humans, and schedules. The production capacity of a shipyard may vary depending on how they are operated. Particularly in the case of ships, it is important to efficiently utilize the limited space because they have large blocks, which are semi-finished products made during the shipbuilding process. To efficiently utilize the space, the locations of blocks must be determined taking various factors into consideration when arranging them in the workshop or stock area. This problem can be described as a spatial arrangement problem. However, as the items with fixed arrival dates and departure dates occupy the space for certain periods before being released from shipyards, this problem must be approached from the perspective of a spatial arrangement planning problem for certain periods and not as a simple spatial arrangement problem. In this study, various shipyard spatial arrangement planning problems are classified and defined based on arrangement areas, arrangement items, algorithms, and evaluation factors. In addition, taking the increasing sizes of shipyard blocks into consideration, evaluation factors and algorithms are proposed so that the shape of the free space and the characteristics of unplaced blocks can be considered in the spatial arrangement planning problems of large blocks. The performances of the proposed evaluation factors and algorithms were verified using block data generated by analyzing existing shipyard data product information. The proposed algorithm performed better than the existing algorithm for spatial arrangement planning problems of large blocks. However, the performance of the proposed algorithm was not significantly different from the existing algorithm when the size of the arrangement item was relatively small compared with the arrangement area.

关键词： greedy algorithm Shipyard simulation system Shipyard information model Spatial arrangement planning problem

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Multi-criteria ranking based greedy algorithm for physical resource block allocation in multi-carrier wireless communication systems

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SIGNAL PROCESSING 2012年第11期92卷 2706-2717页

作者： Nwamadi, Obilor Zhu, Xu Nandi, Asoke K. Univ Liverpool Dept Elect Engn & Elect Liverpool L69 3GJ Merseyside England

A computationally efficient algorithm, referred to as the multi-criteria ranking based greedy (MCRG) algorithm, is proposed for physical resource block (PRB) allocation in multi-carrier wireless communications systems, where the users utilities are ranked with multiple criteria. The MCRG algorithm not only outperforms the previous single criterion ranking based greedy algorithm in terms of throughput and outage probability, but also provides a near optimal performance, irrespective of whether the channel frequency response (CFR) or bit error rate (BER) or throughput optimisation utilities are used. In particular, when the MCRG algorithm is used to optimise the CFR utility, the overall computational complexity is kept at a very low level, without sacrificing the performance. To further reduce the overall computational complexity, a selectivity ratio is included in the MCRG algorithm, where greedy PRB allocation is applied only to a selection of users with lower multi-criteria ranking. (c) 2012 Elsevier B.V. All rights reserved.

关键词： Resource allocation Physical resource block greedy algorithm Multi-criteria ranking Multi-carrier

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