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2014 IEEE 8th International Symposium on Service Oriented System Engineering

作者： Zheng Han Rui Chu Haibo Mi Huaimin Wang Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha Hunan China

Many big data applications receive and process data in real time. These data, also known as data streams, are generated continuously and processed online in a low latency manner. Data stream is prone to change dramatically in volume, since its workload may have a variation of several orders between peak and valley periods. Fully provisioning resources for stream processing to handle the peak load is costly, while over-provisioning is wasteful when to deal with lightweight workload. Cloud computing emphasizes that resource should be utilized economically and elastically. An open question is how to allocate query task adaptively to keeping up the input rate of the data stream. Previous work focuses on using either local or global capacity information to improve the cluster CPU resource utilization, while the bandwidth utilization which is also critical to the system throughput is ignored or simplified. In this paper, we formalize the operator placement problem considering both the CPU and bandwidth usage, and introduce the Elastic Allocator. The Elastic Allocator uses a quantitative method to evaluate a node's capacity and bandwidth usage, and exploit both the local and global resource information to allocate the query task in a graceful manner to achieve high resource utilization. The experimental results and a simple prototype built on top of Storm finally demonstrate that Elastic Allocator is adaptive and feasible in cloud computing environment, and has an advantage of improving and balancing system resource utilization.

关键词： Bandwidth Resource management Clustering algorithms Storms Linear programming Cloud computing Computer architecture

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UWBSS: Ultra-wideband Spectrum Sensing with Multiple Sub-Nyquist Sampling Rates

UWBSS: Ultra-wideband Spectrum Sensing with Multiple Sub-Nyq...

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IEEE International Conference on Computational science and Engineering, CSE

作者： Yong Lu Shaohe Lv Xiaodong Wang Xingming Zhou Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha Hunan China

ISBN: (纸本)9781479979820

In consideration of the continuous increasing demand of wireless data transmission, ultra-wideband spectrum sensing is crucial to support the cognitive communication in a ultra-wide frequency band. However, it is challenging to design ADCs that fulfill the Nyquist rate requirement for a ultra wide band. Spectrum sensing based on the sub-Nyquist sampling maybe the answer. We propose UWBSS: ultra-wideband spectrum sensing. With multiple sub-Nyquist sampling rates, UWBSS can reconstruct the occupied frequencies from the under sampled data directly without complex amplitudes reconstruction. Also We conduct an extensive study to characterize the effect on the accuracy of sub-Nyquist spectrum sensing of sampling rate, bandwidth resolution and the SNR of the original signal. The performance of UWBSS is verified by simulations.

关键词： Sensors Signal to noise ratio Ultra wideband technology Signal resolution Wideband Energy resolution

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Agent-Based Fault Tolerance Mechanism for distributed Key-Value Database

Agent-Based Fault Tolerance Mechanism for Distributed Key-Va...

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International Conference on Digital Home (ICDH)

作者： Wu Hui-jun Lu Kai GenLi Gen Jiang Jin-fei Wang Shuang-xi Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha PR China

ISBN: (纸本)9781479942831

distributed key-value database is widely used in Web 2.0 applications and cloud computing environments. It overcomes the weak performance and bad scalability of traditional relational database. But fault in distributed system will lead to errors, then the high performance is useless. So we should build a fault tolerance mechanism. On the other hand, in many application scenarios, transactional operations are inevitable. Some existing key-value databases utilize two-phase commit protocol or optimistic concurrency control in transaction processing. But the problems are sing-node failure and high overhead in protocol processing. Meanwhile, users' programming becomes more error-prone. This paper designs a fault tolerance and recovery mechanism on DStageDB, which is a distributed key-value database. We design an agent-based transaction processing mechanism. The transaction processing speed is improved and less user intervention is needed.

关键词： Servers Fault tolerance Fault tolerant systems distributed databases Protocols Usability

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AUModel:A Conceptual model for Adaptive Software

AUModel:A Conceptual model for Adaptive Software

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2014 IEEE 5th International Conference on Software Engineering and Service science

作者： Hui Liu Bo Ding Dianxi Shi Huaimin Wang National Key Laboratory for Parallel and Distributed Processing College of Computer ScienceNational University of Defense Technology

Pervasive software should be able to adapt itself to the changing environments and user ***,it will bring great challenges to the software engineering *** paper proposes AUModel,a conceptual model for adaptive software,which takes adaptability as an inherent feature and can act as the foundation of the engineering *** introducing AUModel,the reuse of software adaptation infrastructure as well as the separation of adaptation concerns are enabled,which can facilitate both the development and maintenance of adaptive *** paper also presents our initial attempts to realize this model,including a middleware prototype to support this model and an application to validate its effectiveness.

关键词： pervasive computing adaptive software middleware

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IWFR:Exploiting Full-duplex in Wireless Relay Networks

IWFR:Exploiting Full-duplex in Wireless Relay Networks

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2014 4th IEEE International Conference on Information science and technology

作者： Yong Lu Shaohe Lv Xiaodong Wang Xingming Zhou National Key Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology

Traditional wireless relay networks have large endto-end time delay and low throughput because of the limit that it can't receive and forward at the same *** this paper,we proposed IWFR:Immediate Wireless Full-Duplex Relay which exploits the advantages of full-duplex to shorten the end-to-end time delay and improve the *** the same time,we designed a new implicit acknowledgement mechanism,which can eliminate the ACK overheads and evidently improve the throughput of the *** implement IWFR,we also modified the full-duplex node architecture to make it support for immediate *** shows that IWFR shortens the end-to-end time delay by 60%on average and improves the throughput to 240%of the original relay.

关键词： Relay IWFR:Exploiting Full-duplex in Wireless Relay Networks

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Who should review this pull-request: Reviewer recommendation to expedite crowd collaboration 21

Who should review this pull-request: Reviewer recommendation...

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21st Asia-Pacific Software Engineering Conference, APSEC 2014

作者： Yu, Yue Wang, Huaimin Yin, Gang Ling, Charles X. National Laboratory for Parallel and Distributed Processing College of Computer National University of Defense Technology Changsha410073 China Department of Computer Science University of Western Ontario LondonONN6A 5B7 Canada

ISBN: (纸本)9781479974252

Github facilitates the pull-request mechanism as an outstanding social coding paradigm by integrating with social media. The review process of pull-requests is a typical crowdsourcing job which needs to solicit opinions of the community. Recommending appropriate reviewers can reduce the time between the submission of a pull-request and the actual review of it. In this paper, we firstly extend the traditional Machine Learning (ML) based approach of bug triaging to reviewer recommendation. Furthermore, we analyze social relations between contributors and reviewers, and propose a novel approach to recommend highly relevant reviewers by mining comment networks (CN) of given projects. Finally, we demonstrate the effectiveness of these two approaches with quantitative evaluations. The results show that CN-based approach achieves a significant improvement over the ML-based approach, and on average it reaches a precision of 78% and 67% for top-1 and top-2 recommendation respectively, and a recall of 77% for top-10 recommendation. © 2014 IEEE.

关键词： Learning systems

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A Discrete Data Dividing Approach for Erasure-Code-Based Storage Applications

A Discrete Data Dividing Approach for Erasure-Code-Based Sto...

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2014 IEEE 8th International Symposium on Service Oriented System Engineering

作者： Weidong Sun Yijie Wang Yongquan Fu Xiaoqiang Pei Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha Hunan P. R. China

Erasure codes are promising for improving the reliability of the storage system due to its space efficiency compared to the replication methods. Traditional erasure codes split data into equalsized data blocks and encode strips in different data blocks. This brings heavy repairing traffic when clients read parts of the data, since most strips read for repairing are not in the expected blocks. This paper proposes a novel discrete data dividing method to completely avoid this problem. The key idea is to encode strips from the same data block. We could see that for repairing failed blocks, the strips to be read are either in the same data block with corrupted strips or from the encoded strips. Therefore, no data is wasted. We design and implement this data layout into a HDFS-like storage system. Experiments over a small-scale testbed shows that the proposed discrete data divided method avoids downloading data blocks that are not needed for clients during the repairing operations.

关键词： Strips Decoding Encoding distributed databases Writing Reliability Magnetic heads

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Flexible Virtual Channel Power-Gating for High-Throughput and Low-Power Network-on-Chip

Flexible Virtual Channel Power-Gating for High-Throughput an...

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Euromicro Symposium on Digital System Design

作者： Feng Wang Xiantuo Tang Qinglin Wang Zuocheng Xing Hengzhu Liu Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha Hunan P. R. China

Power-gating is a representative circuit level technique to mitigate leakage power. While in low-power Network-on-Chip (NoC) design, the former fine-grained power-gating methods will decrease network performance due to serial wake-up latency and head-of-line blocking. Therefore, we propose a flexible Virtual Channel (VC) management scheme for fine-grained power-gating to achieve high throughput and low-power. The proposed power-gating method with the early wake-up is evaluated by using some synthetic workloads. When compared with an optimized early wake-up power-gating technique, it can improve performance effectively in medium and high network loads, and increases the network throughput by 15.7%~44.1% for different synthetic loads, while keeps network power consumption as low as the optimized method. For the PARSEC application traces of token based protocol, it can significantly decrease packet latency by 20.3% on average, however only increases less than 3.6% peak power when compared with the optimized method.

关键词： Throughput Radiation detectors Routing Process control Pipelines Power demand Ports (Computers)

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Accuracy evaluation of deep belief networks with fixed-point arithmetic

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Computer Modelling and New Technologies 2014年第6期18卷 7-14页

作者： Jiang, Jingfei Hu, Rongdong Mikel, Lujan Dou, Yong Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology ChangSha Hunan China University of Manchester Manchester United Kingdom

Deep Belief Networks (DBNs) are state-of-art Machine Learning techniques and one of the most important unsupervised learning algorithms. Training DBNs is computationally intensive which naturally leads to investigate FPGA acceleration. Fixed-point arithmetic can be used when implementing DBNs in FPGAs to reduce execution time, but it is not clear the implications for accuracy. Previous studies have focused only on accelerators using some fixed bit-widths. A contribution of this paper is to demonstrate the bit-width effect on various configurations of DBNs in a comprehensive way by experimental evaluation. Explicit performance changing points are found using various bit-widths. The impact of sigmoid function approximation, required part of DBNs, is evaluated. A solution of mixed bit-widths DBN is proposed, fitting the bit-widths of FPGA primitives and gaining similar performance to the software implementation. Our results provide a guide to inform the design choices on bit-widths when implementing DBNs in FPGAs documenting clearly the trade-off in accuracy.

关键词： Field programmable gate arrays (FPGA)

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IWFR: Exploiting full-duplex in wireless relay networks

IWFR: Exploiting full-duplex in wireless relay networks

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International Conference on Information science and technology (ICIST)

作者： Yong Lu Shaohe Lv Xiaodong Wang Xingming Zhou National Key Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha Hunan China

Traditional wireless relay networks have large end-to-end time delay and low throughput because of the limit that it can't receive and forward at the same time. In this paper, we proposed IWFR: Immediate Wireless Full-Duplex Relay which exploits the advantages of full-duplex to shorten the end-to-end time delay and improve the throughput. At the same time, we designed a new implicit acknowledgement mechanism, which can eliminate the ACK overheads and evidently improve the throughput of the relay. To implement IWFR, we also modified the full-duplex node architecture to make it support for immediate relay. Simulation shows that IWFR shortens the end-to-end time delay by 60% on average and improves the throughput to 240% of the original relay.

关键词： Wireless communication Throughput Delay effects Wireless sensor networks Interference Relay networks (telecommunications)

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