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Tree-Structured parallel Regeneration for Multiple Data Losses in distributed Storage Systems Based on Erasure Codes

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China Communications 2013年第4期10卷 113-125页

作者：孙伟东王意洁裴晓强 National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology

To reduce the time required to complete the regeneration process of erasure codes, we propose a Tree-structured parallel Regeneration (TPR) scheme for multiple data losses in distributed storage systems. Under the scheme, two algorithms are proposed for the construction of multiple regeneration trees, namely the edge-disjoint algorithm and edge-sharing algorithm. The edge-disjoint algorithm constructs multiple independent trees, and is simple and appropriate for environments where newcomers and their providers are distributed over a large area and have few intersections. The edge-sharing algorithm constructs multiple trees that compete to utilize the bandwidth, and make a better utilization of the bandwidth, although it needs to measure the available band-width and deal with the bandwidth changes; it is therefore difficult to implement in practical systems. The parallel regeneration for multiple data losses of TPR primarily includes two optimizations: firstly, transferring the data through the bandwidth optimized-paths in a pipe-line manner; secondly, executing data regeneration over multiple trees in parallel. To evaluate the proposal, we implement an event-based simulator and make a detailed comparison with some popular regeneration methods. The quantitative comparison results show that the use of TPR employing either the edge-disjoint algorithm or edge-sharing algorithm reduces the regeneration time significantly.

关键词： distributed storage system erasure code replication regeneration tree

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An integration framework of cloud computing with wireless sensor networks

An integration framework of cloud computing with wireless se...

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7th International Conference on Ubiquitous Information Technologies and Applications, CUTE 2012

作者： You, Pengfei Li, Huiba Peng, Yuxing Li, Ziyang National Key Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology 410073 Changsha China

ISBN: (纸本)9789400758568

Wireless sensor networks (WSN) is a key technology extensively applied in many fields, such as transportation, health-care and environment monitoring. Despite rapid development, the exponentially increasing data emanating from WSN is not efficiently stored and used. Besides, the data from multiple different types and locations of WSN needs to be well analyzed, fused and supplied to various types of clients, such as PC, workstation and smart phone. The emerging cloud computing technology provides scalable data process and storage power and some types of connectable services, which can helpfully utilize sensor data from WSN. In this paper, we propose an integration framework of cloud computing with WSN, in which sensor data is transmitted from WSN to cloud, and processed and stored in cloud, then mined and analyzed so as to be supplied to various clients. By applying virtualization and cloud storage technology, and Infrastructure as a Service (IaaS) and Software as a Service (SaaS) of cloud service model, the framework can fully process and store mass sensor data from multiple types of WSN. Besides, it efficiently mines and analyzes sensor data, based on which the data applications are well supplied to various types of clients in form of services. © 2013 Springer Science+Business Media.

关键词： Virtualization

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Global EDF-based online, energy-efficient real-time scheduling in multi-core platform

Global EDF-based online, energy-efficient real-time scheduli...

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IEEE International Conference on computer Science and Automation Engineering

作者： Zhang, Dongsong Chen, Fangyuan Jin, Shiyao National Laboratory of Parallel and Distributed Processing College of Computer National University of Defense Technology Changsha China

ISBN: (纸本)9781424487257

As the energy consumption becomes increasingly prominent, how to meet time constraints while reducing the energy consumption as much as possible is a fundamental problem of the real-time scheduling in multi-core systems. Most of the existing energy-efficient scheduling approaches make assumptions on the properties of the scheduled tasks. In general, the properties of a task are unknown in advance until the task arrives. Thus, these approaches for deterministic tasks are not suitable to the general tasks. To schedule general tasks without prior knowledge of their properties, we propose an online and energy-efficient scheduling algorithm, based on Global Earliest Deadline First, for hard real-time tasks in multi-core processor platform. We propose a novel approach to decrease the execution frequency of tasks, and achieve a reasonable compromise between the time constraint and saved energy. This is ensured by utilizing the slack time of tasks and the dynamic voltage/frequency scaling techniques. The evaluation results show that our algorithm is well applied to the two types of dynamic voltage/frequency scaling techniques, and out-performs the Global EDF algorithm in terms of the saved energy. Specifically, our algorithm improves the saved energy of the Global EDF algorithm by at most 10% to 15% under real discrete dynamic voltage/frequency scaling levels. © 2011 IEEE.

关键词： Real time systems

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Prediction of the Cyanobacteria Coverage in Time-series Images based on Convolutional Neural Network 21

Prediction of the Cyanobacteria Coverage in Time-series Imag...

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4th International Conference on Control and computer Vision, ICCCV 2021

作者： Ye, Xiangyu Lai, Zhiquan Li, Dongsheng National Key Laboratory of Parallel and Distributed Processing Computer College National University of Defense Technology China

ISBN: (纸本)9781450390477

In recent years, the problem of lake eutrophication has become increasingly severe. The monitoring and control of cyanobacteria in lakes are of great significance. The information obtained by existing monitoring methods is relatively lagging, and it is impossible to monitor the sudden outbreak of cyanobacteria in time. Getting cyanobacteria information directly through camera images is a breakthrough. In this paper, after analyzing the characteristics of time series cyanobacteria images, we propose a block prediction scheme based on the CNN model. Experiments show that this method can quickly calculate the coverage of cyanobacteria in the monitoring image in a short time. It can also effectively distinguish cyanobacteria-rich water areas, which significantly facilitates water quality monitoring and cyanobacteria management. We can draw a chart of the changes in the coverage of cyanobacteria by analyzing multi-day time-series images. The chart helps us conduct a short-term water quality analysis to better deal with the outbreak of cyanobacteria. © 2021 ACM.

关键词： Lakes

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Storage allocation for redundancy scheme in reliability-aware cloud systems

Storage allocation for redundancy scheme in reliability-awar...

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2011 IEEE 3rd International Conference on Communication Software and Networks, ICCSN 2011

作者： Huang, Zhen Yuan, Yuan Peng, Yuxing National Laboratory of Parallel and Distributed Processing Computer Department National University of Defense Technology Changsha China

ISBN: (纸本)9781612844855

As the burst increasing of created and demand on information and data, the efficient solution on storage management is highly required in the cloud storage systems. As an important component of management, storage allocation scheme aims to use a low redundancy and also to achieve a high reliability. However, the two aims are hard to be unified. Considering the practical situation of Cloud systems, we propose a systematic storage allocation scheme to touch them both. And we also study the impact of many factors to the data reliability. © 2011 IEEE.

关键词： Information management

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A novel open source software ecosystem: From a graphic point of view and its application 28

A novel open source software ecosystem: From a graphic point...

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28th International Conference on Software Engineering and Knowledge Engineering, SEKE 2016

作者： Song, Chenxi Wang, Tao Yin, Gang Zhang, Xunhui Yang, Cheng National Laboratory for Parallel and Distributed Processing College of Computer National University of Defense Technology Changsha China

ISBN: (纸本)189170639X

With the rapid development of open source software, various elements such as OSS, developers, users and online posts, across different communities and their interactions constitute a novel software ecosystem. Most of the current researches about software ecosystems care the connections between software, and few of them consider the relationship across communities from an overall perspective, and fail to cover the users and their activities which should be an indispensable part of the OSS ecosystem. This paper model the OSS ecosystem as a graph, which combines different types of OSS communities as a whole. Based on this graph model, we analyze the characteristics of ecosystem, like the evolution, competition and symbiosis. In addition, we build a recommendation system as well, and the experiment results suggest the validation of our approach. Copyright © 2016 by KSI Research Inc. and Knowledge Systems Institute Graduate school.

关键词： Ecosystems

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RETRACTED ARTICLE: parallel block multigrid preconditioner for 3D navier-stokes equations on unstructured grids

RETRACTED ARTICLE: Parallel block multigrid preconditioner f...

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作者： Li, Zongzhe Lu, Yao Cao, Wei Wang, Yongxian Wang, Zhenghua Parallel and Distributed Processing for National Laboratory School of Computer Science National University of Defence Lechnology Changsha Hunan 410073 China

ISBN: (纸本)9781424472369

In this paper, we explore a parallel block multigrid preconditioner based on factorization of the coefficient matrix generated in three-dimensional unstructured grids system. This preconditioner is robust with respect to the magnitude of the mesh size and the coefficient complexity, apply smoothed aggregation algebraic multigrid which using block lower-upper symmetric Gauss-Seidel(BLU-SGS) as smoother to accelerate convergent rate. We focus on this method to three-dimensional, unstructured, large-scale, parallel and NS equations' steady-state simulations. The numerical results which conducted on NACA0012 airfoil indicate that nearly optimal convergence rates and computational complexity for parallel solutions, this method also provide high speedup and efficiency for a series of processors. © 2010 IEEE.

关键词： Navier Stokes equations

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Research of context situation awareness technology

Research of context situation awareness technology

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作者： Shi, Dianxi Wu, Zhendong Ding, Bo Yan, Huining National Key Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9780769546698

Context situation, which means a snapshot of the status of the real world, is formed by integrating a large amount of contexts collected from various resources. How to get the context situation and use the situation to provide better services is a challenging issue. In this paper, we focused on this challenge on the basis of the mobile cloud computing architecture. An abstract model is proposed in this paper to uniformly collect the context and send them to cloud. A rule-based large-scale context aggregation algorithm is also proposed which utilizes the MapReduce computing paradigm. Finally, a large-scale context management framework based on the abstract model and the context aggregation algorithm is proposed, and a real-time traffic demo is implemented to verify the validity of the framework. © 2012 IEEE.

关键词： MapReduce

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Why do they ask? An exploratory study of crowd discussions about Android application programming interface in stack overflow

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Journal of Central South University 2019年第9期26卷 2432-2446页

作者： FAN Qiang WANG Tao YANG Cheng YIN Gang YU Yue WANG Huai-min National Laboratory for Parallel and Distributed Processing College of Computer ChangshaChangsha 410073China

Nowadays,more and more Android developers prefer to seek help from Q&A website like Stack Overflow,despite the rich official *** researches have studied the limitations of the official application programming interface(API)documentations and proposed approaches to improve ***,few of them digged into the requirements of the third-party developers to study *** this work,we gain insight into this question from multidimensional perspectives of API developers and API users by a kind of *** propose a hybrid approach,which combines manual inspection on artifacts and online survey on corresponding developers,to explore the different focus between these two types of *** our work,we manually inspect 1000 posts and receive 319 questionnaires in *** the mutual verification of the inspection and survey process,we found that the users are more concerned with the usage of API,while the official documentation mainly provides functional ***,we identified 9 flaws of the official documentation and summarized 12 aspects(from the content to the representation)for promotion to improve the official API documentations.

关键词： API documentation Android online survey Stack Overflow

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Improving vertex-frontier based GPU breadth-first search

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Journal of Central South University 2014年第10期21卷 3828-3836页

作者：杨博卢凯高颖慧徐凯王小平程志权 Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology College of Computer National University of Defense Technology Department of Electronic Science and Engineering National University of Defense Technology Avatar Science Company

Breadth-first search(BFS) is an important kernel for graph traversal and has been used by many graph processing applications. Extensive studies have been devoted in boosting the performance of BFS. As the most effective solution, GPU-acceleration achieves the state-of-the-art result of 3.3×109 traversed edges per second on a NVIDIA Tesla C2050 GPU. A novel vertex frontier based GPU BFS algorithm is proposed, and its main features are three-fold. Firstly, to obtain a better workload balance for irregular graphs, a virtual-queue task decomposition and mapping strategy is introduced for vertex frontier expanding. Secondly, a global deduplicate detection scheme is proposed to remove reduplicative vertices from vertex frontier effectively. Finally, a GPU-based bottom-up BFS approach is employed to process large frontier. The experimental results demonstrate that the algorithm can achieve 10% improvement over the state-of-the-art method on diverse graphs. Especially, it exhibits 2-3 times speedup on low-diameter and scale-free graphs over the state-of-the-art on a NVIDIA Tesla K20 c GPU, reaching a peak traversal rate of 11.2×109 edges/s.

关键词： breadth-first search GPU graph traversal vertex frontier

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