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International Conference on Advanced Information Networking and Applications (AINA)

作者： Mohsen Amini Salehi Bahman Javadi Rajkumar Buyya Cloud Computing and Distributed Systems (CLOUDS) Laboratory Department of Computer Science and Software Engineering University of Melbourne Australia

Many applications in federated Grids have quality-of-service (QoS) constraints such as deadline. Admission control mechanisms assure QoS constraints of the applications by limiting the number of user requests accepted by a resource provider. However, in order to maximize their profit, resource owners are interested in accepting as many requests as possible. In these circumstances, the question that arises is: what is the effective number of requests that can be accepted by a resource provider in a way that the number of accepted external requests is maximized and, at the same time, QoS violations are minimized. In this paper, we answer this question in the context of a virtualized federated Grid environment, where each Grid serves requests from external users along with its local users and requests of local users have preemptive priority over external requests. We apply analytical queuing model to address this question. Additionally, we derive a preemption-aware admission control policy based on the proposed model. Simulation results under realistic working conditions indicate that the proposed policy improves the number of completed external requests (up to 25%). In terms of QoS violations, the 95% confidence interval of the average difference with other policies is between (14.79%, 18.56%).

关键词： Admission control Mathematical model Equations Analytical models Time factors Queueing analysis

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Financial Option Market Model for Federated Cloud Environments

Financial Option Market Model for Federated Cloud Environmen...

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IEEE International Conference on Utility and Cloud Computing (UCC)

作者： Adel Nadjaran Toosi Ruppa K. Thulasiram Rajkumar Buyya Cloud Computing and Distributed Systems (CLOUDS) Laboratory Department of Computing and Information Systems University of Melbourne Australia Department of Computer Science University of Manitoba Canada

Pay-per-use service by Cloud service providers has attracted customers in the recent past and is still evolving. Since the resources being dealt within Clouds are non-storable and the physical resources need to be replaced very often, pricing the service in a way that would return profit on the initial capital investments to the service providers has been a major issue. Moreover, to maintain Quality of Service (QoS) to customers who reserve the resources in advance and may or may not be using the resources at a future date makes the resources wasted, if not allocated to other on-demand users. Therefore, a need for a mechanism to guarantee the resources to reserved users whenever they need them, while keeping the resources busy all the time is in very high demand. The concept of federation of Cloud service providers has been proposed in the past wherein resources are traded between the providers whenever need arises. We propose a financial option based Cloud resources pricing model to address the above situation. This model allows a provider to hedge the critical and risky situation of reserved users requesting the resources while all the resources have been allocated to other users, by trading (buying or outsourcing) resources from other service providers in the Cloud federation. We show that using financial option based contracts between Cloud providers in a Cloud federation, providers are able to enhance profit and acquire the needed resources at any given time. It would also help creating a trust and goodwill from the clients on the Cloud service providers by less number of QoS violation.

关键词： Contracts Pricing Quality of service Cloud computing Availability Computational modeling Load modeling

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Combining gait research of the quadruped/biped reconfigurable walking chair with parallel leg mechanism

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4th International Conference on Social Robotics, ICSR 2012

作者： Hu, Xing Wang, Hongbo Sang, Lingfeng Gu, Qifang Yuan, Lin School of Mechanical and Electrical Engineering Xi'an University of Architecture and Technology Xi'an Shanxi 710055 China Ministry of Education Key Laboratory of Advanced Forging Technology and Science Hebei Province Key Laboratory of Parallel Robot and Mechatronics Systems Yanshan University Qinhuangdao Hebei 066004 China Department of Computer Wuxi City College of Vocational Technology Wuxi 214063 China

ISBN: (纸本)9783642341021

The quadruped/biped reconfigurable walking robot with parallel leg mechanism can realize not only the quadruped walking, but also the biped walking. The converting process from the quadruped to the biped includes locking the vertical revolute pair hinged with the upper platform and combining the corresponding lower platforms. Based on the previous study, the combining schemes of walking chair are researched in this paper, and then the correctness of the combining schemes is analyzed by using the position workspace of the swing leg and the body mechanism in different states which are obtained by the MATLAB software and anti-solution search method. Compared with the stability margin and the adjustment coordination of the body in the different combining schemes, the optimal combining gaits of walking chair are selected, which lays the theoretical foundation for the quadruped/biped converting control of walking chair. © 2012 Springer-Verlag.

关键词： MATLAB

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Speeding up the MATLAB complex networks package using graphic processors

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Chinese Physics B 2011年第9期20卷 460-467页

作者：张百达唐玉华吴俊杰李鑫 National laboratory for Parallel and Distributed Processing School of ComputerNational University of Defense Technology Department of Computer Science and Technology School of ComputerNational University of Defense Technology

The availability of computers and communication networks allows us to gather and analyse data on a far larger scale than previously. At present, it is believed that statistics is a suitable method to analyse networks with millions, or more, of vertices. The MATLAB language, with its mass of statistical functions, is a good choice to rapidly realize an algorithm prototype of complex networks. The performance of the MATLAB codes can be further improved by using graphic processor units （GPU）. This paper presents the strategies and performance of the GPU implementation of a complex networks package, and the Jacket toolbox of MATLAB is used. Compared with some commercially available CPU implementations, GPU can achieve a speedup of, on average, 11.3x. The experimental result proves that the GPU platform combined with the MATLAB language is a good combination for complex network research.

关键词： complex networks graphic processors unit MATLAB Jacket Toolbox

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Kernel methods based approaches to image classification and retrieval

Kernel methods based approaches to image classification and ...

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International Conference on Advanced Computing, ICAC

作者： C. Chandra Sekhar Sasi Kumar Madhan Subhas Raj Kumar Buyya Department of Computer Science and Engineering Indian Institute of Technology Madras CDAC Pune Chronus Corporation Computer Science and Software Engineering and Director of the Cloud Computing and Distributed Systems (CLOUDS) Laboratory at the University of Melbourne Australia

Support vector machine (SVM) is a pattern classification model suitable for classification and annotation of images using non-vectorial type representations of images. Varying length patterns extracted from image data correspond to sets of local feature vectors. Kernels designed for varying length patterns are called as dynamic kernels. The talk presents the issues in designing the dynamic kernel based SVMS for classification and annotation of images. Different methods for designing the dynamic kernels are presented. An intermediate matching kernel (IMK) for a pair of varying length patterns is constructed by matching the pairs of local feature vectors selected using a set of virtual feature vectors. For patterns corresponding to sets of feature vectors, a Gaussian mixture model (GMM) is used as the set of virtual feature vectors. The GMM-based IMK is considered for image processing tasks such as image classification, matching and annotation in content-based image retrieval. The talk presents results of experimental studies on image classification, annotation and retrieval of images using the kernel methods.

关键词： Cloud computing Kernel Technological innovation Support vector machine classification Learning systems Hidden Markov models Computational modeling

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A science gateway getting ready for serving the international molecular simulation community 2

A science gateway getting ready for serving the internationa...

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2012 EGI Community Forum / EMI 2nd Technical Conference, EGICF-EMITC 2012

作者： Gesing, Sandra Herres-Pawlis, Sonja Birkenheuer, Georg Brinkmann, André Grunzke, Richard Kacsuk, Peter Kohlbacher, Oliver Kozlovszky, Miklos Krüger, Jens Müller-Pfefferkorn, Ralph Schäfer, Patrick Steinke, Thomas Center for Bioinformatics Department of Computer Science University of Tübingen Sand 14 Tübingen72076 Germany Department of Chemistry Ludwig-Maximilians-University Munich Butenandtstr. 5-13 München81377 Germany Paderborn Center for Parallel Computing University of Paderborn Warburger Str. 100 Paderborn33089 Germany Johannes Gutenberg-University Mainz Mainz55099 Germany Center for Information Services and High Performance Computing Technische Universität Dresden Zellescher Weg 12-14 Germany Laboratory of Parallel and Distributed Systems MTA SZTAKI Kende Street 13-17 Budapest1111 Hungary Zuse Institute Berlin Takustraße 7 Berlin14195 Germany

The project MoSGrid (Molecular Simulation Grid) has been developing a web-based science gateway supporting the community with various services for quantum chemistry, molecular modeling, and docking. Users gain access to distributed computing infrastructures (DCIs) via intuitive user interfaces for sophisticated tools, specialized workflows, and distributed repositories. Currently, the MoSGrid community consists of about 120 users from a number of fields related to chemistry and bioinformatics located in Germany. However, the underlying security infrastructure is generally applicable and can be deployed in arbitrary projects. MoSGrid intends to address the international community by participating in the EU-projects SCI-BUS (Scientific gateway Based User Support) and ER-flow (Building an European Research Community through Interoperable Workflows and Data), and collaborating with the EU-project EDGI (European Desktop Grid Initiative). © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.

关键词： Quantum chemistry

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Betweenness-based algorithm for a partition scale-free graph

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Chinese Physics B 2011年第11期20卷 556-564页

作者：张百达吴俊杰唐玉华周静 National Laboratory for Parallel and Distributed Processing School of ComputersNational University of Defense Technology Department of Computer Science and Technology School of ComputersNational University of Defense Technology

Many real-world networks are found to be scale-free. However, graph partition technology, as a technology capable of parallel computing, performs poorly when scale-free graphs are provided. The reason for this is that traditional partitioning algorithms are designed for random networks and regular networks, rather than for scale-free networks. Multilevel graph-partitioning algorithms are currently considered to be the state of the art and are used extensively. In this paper, we analyse the reasons why traditional multilevel graph-partitioning algorithms perform poorly and present a new multilevel graph-partitioning paradigm, top down partitioning, which derives its name from the comparison with the traditional bottom-up partitioning. A new multilevel partitioning algorithm, named betweenness-based partitioning algorithm, is also presented as an implementation of top-down partitioning paradigm. An experimental evaluation of seven different real-world scale-free networks shows that the betweenness-based partitioning algorithm significantly outperforms the existing state-of-the-art approaches.

关键词： graph partitioning betweenness-based partitioning algorithm scale free network

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COSMIC Measurements Dispersion

COSMIC Measurements Dispersion

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Joint Conference of the Int'l Workshop on and International Conference on Software Process and Product Measurement Software Measurement

作者： Juan J. Cuadrado-Gallego Pablo Rodríguez-Soria Alberto Lucendo Robert Neumann Reiner Dumke Andreas Schmietendorf Software Measurement Laboratory Department of Computer Science University of Alcalá Madrid Spain Department of Distributed Systems Otto-von-Guericke University Magdeburg Germany Department of Cooperative Studies Berlin School of Economics and Law Berlin Germany

Over the years, software functional size measurement has become a viable tool to determine the effort and time needed to carry out a software project. This growth has led to an increased interest, as shown in several studies, as well as to the development and optimization of functional size measurement units. IFPUG Function Points since their development have been the most widely used functional size estimation approach. However, during recent years, a new method, called COSMIC FFP, has emerged as a second generation unit for functional software measurement, and has brought new features and benefits. The aim of this paper is to study the error that is introduced together with the interpretation of the unit application rules, thereby focusing on COSMIC CFPs. Due to subjectivity and degrees of freedom, this error can lead to great measurement dispersions. We have analyzed these dispersions, based upon a study that we have performed at our university, together with a group of Master students.

关键词： Software measurement Software Dispersion Manuals Size measurement ISO standards

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Modeling and analysis of sharing ratio enforcement in private BitTorrent communities

Modeling and analysis of sharing ratio enforcement in privat...

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2011 IEEE International Conference on Communications, ICC 2011

作者： Jia, Adele L. D'Acunto, Lucia Meulpolder, Michel Pouwelse, Johan A. Parallel and Distributed Systems Group Department of Computer Science Delft University of Technology Netherlands

ISBN: (纸本)9781612842332

Providing incentives for user contribution has been one of the primary design goals of Peer-to-Peer systems. The newly-emerged BitTorrent private communities adopt Sharing Ratio Enforcement (SRE) on top of BitTorrent's incentive mechanism, Tit-For-Tat, in order to strictly enforce a minimum contribution a member has to provide, in relation to the amount of service it has received. In this paper, we provide a theoretical model to analyze 1) how SRE provides seeding incentives, and 2) how SRE influences the download performance in the system. Specifically, we study the influence of the SRE threshold (i.e., the minimum sharing ratio requirement) and the bandwidth heterogeneity of the peers in the system. In our analysis, we assume users to be rational, i.e., peers seed only the minimum amount required by SRE, and we show that the download performance as predicted by our model represents a lower bound for the actual performance that can be reached in a BitTorrent private community. Hence, following our model, community administrators can predict the minimum performance level their systems will be able to reach. © 2011 IEEE.

关键词： Peer to peer networks

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BitTorrent's dilemma: Enhancing reciprocity or reducing inequity

BitTorrent's dilemma: Enhancing reciprocity or reducing ineq...

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2011 IEEE Consumer Communications and Networking Conference, CCNC'2011

作者： Jia, Adele L. D'Acunto, Lucia Meulpolder, Michel Pouwelse, Johan A. Epema, Dick H. J. Parallel and Distributed Systems Group Department of Computer Science Delft University of Technology Netherlands

ISBN: (纸本)9781424487905

Enhancing reciprocity has been one of the primary motivations for the design of incentive policies in BitTorrent-like P2P systems. Reciprocity implies that peers need to contribute their bandwidth to other peers if they want to receive bandwidth in return. However, the over-provisioning that characterizes today's BitTorrent communities and the development of many next-generation P2P systems with real-time constraints (e.g., for live and on-demand streaming) suggest that more effort can be devoted to reducing the inequity (i.e., the difference of service received) among peers, rather than only enhancing reciprocity. Inspired by this observation, in this work we analyze in detail several incentive mechanisms that are used in BitTorrent systems, and explore several strategies that influence the balance between reciprocity and equity. Our study shows that (i) reducing inequity leads to a better overall system performance, and (ii) the behavior of seeders (i.e., peers that hold a complete copy of the file and upload it for free) influences whether reciprocity is enhanced or inequity reduced. © 2011 IEEE.

关键词： Bandwidth

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