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Keep Hot or Go Cold: A Randomized online Migration algorithm for Cost Optimization in STaaS Clouds

IEEE TRANSACTIONS ON NETWORK AND SERVICE MANAGEMENT 2021年第4期18卷 4563-4575页

作者： Liu, Mingyu Pan, Li Liu, Shijun Shandong Univ Sch Software Jinan 250101 Peoples R China

Storage-as-a-Service clouds generally offer both hot and cold storage tiers with different pricing options. Hot tiers provide a higher storage price but a lower access price, and vice versa for cold tiers. Many studies show that those user-generated data generally receive relatively high access frequency in the early period of their lifetimes while the overall trend of accesses is downward. Thus, when such kinds of data are hosted in clouds, they can be stored in hot tiers initially and then migrated to cold tiers for optimizing costs. However, the cost of migration is non-negligible, and the number of accesses may then unexpectedly increase after migration, which indicates that a rash migration will incur more costs instead of cost-savings. For making optimal migration decisions, future data access curves are needed, but it is generally very hard to predict them precisely. To solve this problem, in this paper we propose a randomized online algorithm to optimize costs for those user-generated data stored in clouds, without requiring any future information. We show theoretically that the proposed algorithm can achieve a guaranteed competitive ratio of 1+ 2(1-lambda)/e-3+2 lambda+lambda/alpha, and it can be easily extended with prediction windows when short-term predictions are reliable. Eventually, we validate the effectiveness of our proposed algorithms through simulations driven by real-world video-visiting traces collected from a well-known video-sharing website.

关键词： Cost optimization online algorithm competitive analysis storage-as-a-service cloud

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Exploration of a disrupted road network after a disaster with an online routing algorithm

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OR SPECTRUM 2021年第1期43卷 289-326页

作者： Reyes-Rubiano, Lorena Voegl, Jana Rest, Klaus-Dieter Faulin, Javier Hirsch, Patrick Univ Nat Resources & Life Sci Inst Prod & Logist Vienna Austria Univ Publ Navarra Inst Smart Cities Pamplona Spain

This paper considers the problem of supporting immediate response operations after a disaster with information about the available road network to reach certain locations. We propose an online algorithm that aims to minimize the route length required by an unmanned aerial vehicle (UAV) to explore the road accessibility of potential victim locations. It is assumed that no information about disruptions in the road network is available at the start of the exploration. The online algorithm applies two movement and three orientation strategies. Additionally, a cutting strategy is used to restrict the search space after new information about the state of single roads is obtained. We consider a road and an aerial network for the movements of the UAV, since it is not necessary to follow the route of a road any longer, if it can be marked as disrupted. In extensive numerical studies with artificial and real-world test instances, it is evaluated for different disruption levels, which combinations of movement and orientation strategies perform best. Additionally, we propose different refuelling strategies for the UAV and present how they differ in the number of refuelling operations and the required additional route length. The results show that an efficient online algorithm can save valuable exploration time.

关键词： Disrupted road network Immediate response operations online algorithm Aerial vehicles for humanitarian operations online exploration strategies Disaster management

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online algorithm for data retrieval with multiple antennae in wireless communication

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INTERNATIONAL JOURNAL OF SENSOR NETWORKS 2019年第2期31卷 78-89页

作者： He, Ping Li, Weidong Cao, Shufu Ma, Siyuan Shi, Kaihua Hebei Univ Econ & Business Inst Informat Technol Shijiazhuang 050000 Hebei Peoples R China Shijiazhuang Business Bur Shijiazhuang 050000 Hebei Peoples R China

Given a set of requested data items and a set of multiple channels, online multi-antennae data retrieval problem (OMAP) is to download all requested data items from these channels when the clients are equipped with multiple antennae and do not know any a-prior knowledge of wireless data broadcast system, such that the total access latency is minimised and the access latency among all antennae keeps balance. So this paper proposes online multiple antennae data retrieval algorithm based on requested ratio (OMR) and online multiple antennae retrieval algorithm for equal data items based on unretrieved ratio (OMU) that introduces the requested ratio and unretrieved ratio respectively when the length of data items is equal. In addition, when the length of data items is unequal, the paper proposes online multiple antennae retrieval algorithm for unequal data items based on length ratio (OML) that introduces the length to compute the length ratio. Finally, we analyse the competitive rates of three algorithms. Through experiments, the proposed schemes can have currently better efficiency by comparing with some existing schemes and solve OMAP.

关键词： mobile computing wireless communication data retrieval multiple antennae online algorithm

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An online algorithm for Selling Your Reserved IaaS Instances in Amazon EC2 Marketplace 26

An Online Algorithm for Selling Your Reserved IaaS Instances...

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IEEE International Conference on Web Services (IEEE ICWS) part of the IEEE World Congress on Services

作者： Yang, Shengsong Pan, Li Liu, Shijun Shandong Univ Sch Software Jinan 250101 Peoples R China

ISBN: (纸本)9781728127170

In cloud platforms such as Amazon EC2, users can reserve IaaS instances rather than buy on-demand ones to save cost. But it would incur the waste of reservations if there are few demands arriving after reserving instances. Currently, there is a reserved instance marketplace launched by Amazon EC2 cloud, where users can sell their unused instances for avoiding such waste of unused reservations. But for users, it is difficult to make the decision to sell their instances optimally without knowing any information for future demands, for it would incur the extra cost when there are new demands arriving after selling their reservations. For solving this problem, an online selling algorithm is proposed in this paper to guide cloud users in selling reserved instances in Amazon EC2 marketplace. We prove theoretically that our online algorithm A(beta) can guarantee a bounded competitive ratio of 2T/beta, whose value is specific to the type of reserved instances. Taking the *** instance provided by Amazon EC2 as an example, the competitive ratio is 3.36 under its pricing rules for 1-year term. Finally, via extensive experiments using workload data collected from actual applications, we verify our online algorithm's effectiveness and demonstrate that it is much more cost effective to cloud users in IaaS platforms.

关键词： cloud IaaS online algorithm cost management competitive analysis

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online algorithm for Velocity Estimation in Ultrasonic Doppler Measurement

Online Algorithm for Velocity Estimation in Ultrasonic Doppl...

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2018 International Conference on Computer Science, Electronics and Communication Engineering（CSECE2018）

作者： Enyao Shang Jinchun Hu Shengwu Du State Key Laboratory of Tribology Department of Mechanical Engineering Tsinghua University

Ultrasonic Doppler technique is widely used for velocity estimation in medical electronic systems. This technique is signal-processing intensive with an increasing requirement on accuracy, real time and stability. The clutter caused by human tissues contains little information about blood flow velocity. Since conventional algorithms are based on an idealized signal model where the residual clutter is not fully considered, highperformance filters are required for clutter rejection in ultrasonic Doppler measurement. This paper focuses on how to extract the velocity information from ultrasonic echo signals without extra filters. We presented an online algorithm that identified the clutter as unknown parameters instead of filtering. The algorithm does not rely on the performance of extra clutter filters. Simulation results show that this algorithm is simpler and more stable than conventional correlation algorithms.

关键词： online algorithm velocity estimation ultrasonic Doppler filter

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A primal-dual online algorithm for the κ-server problem on weighted HSTs

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JOURNAL OF COMBINATORIAL OPTIMIZATION 2017年第4期34卷 1133-1146页

作者： Chen, Wenbin Li, Fufang Wang, Jianxiong Qi, Ke Tang, Maobin Wang, Xiuni Guangzhou Univ Dept Comp Sci Guangzhou Guangdong Peoples R China Guangzhou Univ Guangdong Prov Engn Technol Res Ctr Math Educ Sof Guangzhou Guangdong Peoples R China Nanjing Univ State Key Lab Novel Software Technol Nanjing Jiangsu Peoples R China

In this paper, we show that there is a 5/2 l .ln(1+ kappa)-competitive randomized algorithm for the kappa-sever problem on weighted Hierarchically Separated Trees (HSTs) with depth l when n = kappa + 1 where n is the number of points in the metric space, which improved previous best competitive ratio 12l ln(1 + 4l (1 + k)) by Bansal et al. (FOCS, pp 267-276, 2011).

关键词： kappa-server problem online algorithm Primal-dual method Randomized algorithm

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An Efficient online algorithm for Dynamic SDN Controller Assignment in Data Center Networks

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IEEE-ACM TRANSACTIONS ON NETWORKING 2017年第5期25卷 2788-2801页

作者： Wang, Tao Liu, Fangming Xu, Hong Huazhong Univ Sci & Technol Sch Comp Sci & Technol Serv Comp Technol & Syst Lab Cluster & Grid Comp Lab Wuhan 430074 Hubei Peoples R China City Univ Hong Kong Dept Comp Sci Hong Kong Hong Kong Peoples R China

Software defined networking is increasingly prevalent in data center networks for it enables centralized network configuration and management. However, since switches are statically assigned to controllers and controllers are statically provisioned, traffic dynamics may cause long response time and incur high maintenance cost. To address these issues, we formulate the dynamic controller assignment problem (DCAP) as an online optimization to minimize the total cost caused by response time and maintenance on the cluster of controllers. By applying the randomized fixed horizon control framework, we decompose DCAP into a series of stable matching problems with transfers, guaranteeing a small loss in competitive ratio. Since the matching problem is NP-hard, we propose a hierarchical two-phase algorithm that integrates key concepts from both matching theory and coalitional games to solve it efficiently. Theoretical analysis proves that our algorithm converges to a near-optimal Nash stable solution within tens of iterations. Extensive simulations show that our online approach reduces total cost by about 46%, and achieves better load balancing among controllers compared with static assignment.

关键词： Software defined networking data center network online algorithm stable matching coalitional game

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Apriori Rule-Based In-App Ad Selection online algorithm for Improving Supply-Side Platform Revenues

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ACM TRANSACTIONS ON MANAGEMENT INFORMATION SYSTEMS 2017年第2-3期8卷 10-10页

作者： Mukherjee, Anik Sundarraj, R. P. Dutta, Kaushik Indian Inst Technol Dept Management Studies Sardar Patel Rd Madras 600036 Tamil Nadu India Univ S Florida Dept Informat Syst & Decis Sci Muma Coll Business 4202 E Fowler AveCIS1040 Tampa FL USA

Today, smartphone-based in-app advertisement forms a substantial portion of the online advertising market. In-app publishers go through ad-space aggregators known as Supply-Side Platforms (SSPs), who, in turn, act as intermediaries for ad-agency aggregators known as demand-side platforms. The SSPs face the twin issue of making ad placement decisions within an order of milliseconds, even though their revenue streams can be optimized only by a careful selection of ads that elicit appropriate user responses regarding impressions, clicks, and conversions. This article considers the SSP's perspective and presents an online algorithm that balances these two issues. Our experimental results indicate that the decision-making time generally ranges between 20 ms and 50 ms and accuracy from 1% to 10%. Further, we conduct statistical analysis comparing the theoretical complexity of the online algorithm with its empirical performance. Empirically, we observe that the time is directly proportional to the number of incoming ads and the number of online rules.

关键词： Supply-side platform demand-side platform online algorithm Apriori algorithm rule generation integer linear programming optimization

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An Optimal online algorithm for Fractional Scheduling on Uniform Machines with Three Hierarchies

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Journal of Systems Science & Complexity 2016年第6期29卷 1650-1657页

作者： LU Xinrong LIU Zhaohui Department of Mathematics East China University of Science and Technology

This paper is concerned with the fractional version of online hierarchical scheduling problem on uniform *** the problem,the jobs and machines have several different hierarchies and each job can be arbitrarily split between the machines with hierarchies not above the hierarchy of the *** objective is to minimize the *** authors present an optimal algorithm for the problem with three hierarchies.

关键词： Fractional scheduling hierarchical scheduling online algorithm uniform machine.

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A clique-based online algorithm for constructing optical orthogonal codes

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APPLIED SOFT COMPUTING 2016年第0期47卷 21-32页

作者： Zhang, Yuan Peng, Mao Yang, Shengxiang Nanjing Univ Informat Sci & Technol Sch Math & Stat Nanjing 210044 Jiangsu Peoples R China De Montfort Univ Sch Comp Sci & Informat CCI Leicester LE1 9BH Leics England

An optical orthogonal code (OOC) is a family of binary sequences with good auto- and cross-correlation properties. In the literature, various mathematical tools have been used to construct OOCs with specific parameters. But, to find a complete solution for constructing OOCs with an arbitrary setting of parameters is still difficult at the moment. In this paper, a clique-based online algorithm is proposed to construct OOCs of relatively large sizes. In the proposed algorithm, the construction of OOCs is reduced to the maximum clique problem based on specially generated graphs, where vertices represent the codewords of an OOC and edges represent the cross-correlation relationships between codeword pairs. In order to overcome the limitation of computer memory for storing large graphs, part of the graph vertices are supposed to arrive sequentially to be fed into the proposed algorithm, and a specially designed evolutionary algorithm is used to find the maximum clique of the current graph when new vertices arrive. The proposed algorithm does not use parameter-specific techniques and hence can be used for different code weight and correlation constraints. Experiments show that the proposed algorithm outperforms an offline evolutionary algorithm with guided mutation on constructing OOCs. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Optical orthogonal codes Evolutionary algorithm Maximum clique problem online algorithm

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