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A general framework for computing maximal contractions

Frontiers of computer science 2013年第1期7卷 83-94页

作者： Jie LUO State Key Laboratory of Software Development Environment School of Computer Science and Engineering Beihang University Beijing 100191 China

This paper investigates the problem of computing all maximal contractions of a given formula set F with re- spect to a consistent set A of atomic formulas and negations of atomic formulas. We first give a constructive definition of minimal inconsistent subsets and propose an algorithmic framework for computing all minimal inconsistent subsets of any given formula set. Then we present an algorithm to com- pute all maximal contractions from minimal inconsistent sub- sets. Based on the algorithmic framework and the algorithm, we propose a general framework for computing all maximal contractions. The computability of the minimal inconsistent subset and maximal contraction problems are discussed. Fi- nally, we demonstrate the ability of this framework by apply- ing it to the first-order language without variables and design an algorithm for the computation of all maximal contractions.

关键词： maximal contraction minimal inconsistent sub- set computability algorithms

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Multi-threaded code generation from Signal program to OpenMP

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Frontiers of computer science 2013年第5期7卷 617-626页

作者： Kai HU Teng ZHANG Zhibin YANG State Key Laboratory of Software Development Environment Beihang University Beijing 100191 China School of Computer Science and Engineering Beihang University Beijing 100191 China IRIT-CNRS Universite de Toulouse Toulouse 31062 France

The use of multi-core processors will become a trend in safety critical systems. For safe execution of multi- threaded code, automatic code generation from formal spec- ification is a desirable method. Signal, a synchronous lan- guage dedicated for the functional description of safety crit- ical systems, provides soundness semantics for determinis- tic concurrency. Although sequential code generation of Sig- nal has been implemented in Polychrony compiler, deter- ministic multi-threaded code generation strategy is still far from mature. Moreover, existing code generation methods use certain multi-thread library, which limits the cross plat- form executions. OpenMP is an application program inter- face （API） standard for parallel programming, supported by several mainstream compilers from different platforms. This paper presents a methodology translating Signal program to OpenMP-based multi-threaded C code. First, the intermedi- ate representation of the core syntax of Signal using syn- chronous guarded actions is defined. Then, according to the compositional semantics of Signal equations, the Signal pro- gram is synthesized to dependency graph （DG）. After par- allel tasks are extracted from dependency graph, the Signal program can be finally translated into OpenMP-based C code which can be executed on multiple platforms.

关键词： multi-thread synchronous language Signal,code generation OpenMP

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Social-aware relay node selection in delay tolerant networks

Social-aware relay node selection in delay tolerant networks

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2013 IEEE 2013 22nd International Conference on computer Communication and Networks, ICCCN 2013

作者： Wei, Kaimin Zeng, Deze Guo, Song Xu, Ke State Key Lab. of Software Development Environment Beihang University China School of Computer Science and Engineering University of Aizu Japan

ISBN: (纸本)9781467357746

In Delay Tolerant Networks (DTNs), the connections between mobile nodes are intermittent and constant end-to-end paths rarely exist. In order to achieve high delivery ratio, most existing DTN routing algorithms favor the ''multi-hop forwarding'' fashion where a message can be forwarded by multiple relay nodes in the hope that one of the employed relay nodes can deliver the message to the destination node. Since aggressively employing relay nodes may incur intolerable delivery cost to resource-constrained mobile nodes in DTNs, it is significant to design a cost-efficient routing protocol that can achieves high delivery ratio. In this paper, we first utilize the small-world feature to limit the maximum forwarding hops in a reasonable way and then propose a greedy relay node selection strategy. A cost-efficient social-aware forwarding algorithm called TBSF (the-best-so-far) is then presented. Extensive simulations on real mobility traces are conducted to evaluate the performance of TBSF. Simulation results show that, in comparison with several well-known routing algorithms, TBSF can achieve high performance in terms of delivery ratio and delivery delay while with much lower delivery cost. © 2013 IEEE.

关键词： Delay tolerant networks

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Analysis and optimization of CFS scheduler on NUMA-based systems

Analysis and optimization of CFS scheduler on NUMA-based sys...

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2012 International Conference on Emerging Technologies for Information Systems, Computing, and Management, ICM 2012

作者： Tian, Hongyun Zhang, Kun Ruan, Li Zhu, Mingfa Xiao, Limin Li, Xiuqiao Liu, Yuhang State Key Laboratory of Software Development Environment Beijing China School of Computer Science and Engineering Beihang University Beijing China

ISBN: (纸本)9781461470090

Non Uniform Memory Access (NUMA) architecture becomes more and more popular as it has better scalability than Uniform Memory Access (UMA). However, all previous work on the operation system scheduler assumed that the underlying system is UMA. As a result, the performance degrades on NUMA machines due to lacking of consideration to the underlying hardware. Researchers discover that the Completely Fair Scheduler (CFS) does not work smoothly on NUMA machines and even interfere performance relative to the O (1) scheduler. In this paper researchers investigate the causes for the performance decline and devise an architecture aware task-bound approach for NUMA system, which can help the CFS scheduler works efficiently on NUMA platforms. The evaluation shows that the approach can upgrade the system performance by more than 60 % on average. The research has great significance to the development and popularity of domestic operating system. © 2013 Springer science+Business Media New York.

关键词： Scheduling

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An evaluation framework for software crowdsourcing

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Frontiers of computer science 2013年第5期7卷 694-709页

作者： Wenjun WU Wei-Tek TSAI Wei LI State Key Laboratory of Software Development Environment Beihang University Beijing 100191 China School of Computing Informatics and Decision Systems Engineering Arizona State University Tempe AZ85281 USA Department of Computer Science and Technology INLIST Tsinghua University Beijing 100084 China

Recently software crowdsourcing has become an emerging area of software engineering. Few papers have pre- sented a systematic analysis on the practices of software crowdsourcing. This paper first presents an evaluation frame- work to evaluate software crowdsourcing projects with re- spect to software quality, costs, diversity of solutions, and competition nature in crowdsourcing. Specifically, competi- tions are evaluated by the min-max relationship from game theory among participants where one party tries to minimize an objective function while the other party tries to maximize the same objective function. The paper then defines a game theory model to analyze the primary factors in these min- max competition rules that affect the nature of participation as well as the software quality. Finally, using the proposed eval- uation framework, this paper illustrates two crowdsourcing processes, Harvard-TopCoder and AppStori. The framework demonstrates the sharp contrasts between both crowdsourc- ing processes as participants will have drastic behaviors in engaging these two projects.

关键词： crowdsourcing software engineering competi-tion rules game theory

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A framework for porting linux OS to a cc-NUMA server based on loongson processors

A framework for porting linux OS to a cc-NUMA server based o...

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2012 International Conference on Emerging Technologies for Information Systems, Computing, and Management, ICM 2012

作者： Zhang, Kun Tian, Hongyun Ruan, Li Xiao, Limin Li, Yongnan Liu, Yuhang State Key Laboratory of Software Development Environment Beihang University Beijing China School of Computer Science and Engineering Beihang University Beijing China

ISBN: (纸本)9781461470090

In order to make the Linux operating system available on a cache coherence NUMA (cc-NUMA) server based on Loongson processors, a family of general-purpose MIPS64 CPUs developed by the Institute of Computing Technology in China, this paper proposes a framework for porting Linux operating system to this cc-NUMA server. Researchers present the overall port scheme after analyzing the framework of the Linux kernel and the architecture of the hardware platform, and then they discuss the transplantation in details with processor-level transplantation, memory management transplantation, interrupt and trap transplantation. The performance evaluation shows that the whole system works stable and the ported operating system could reach about 30 % of the theoretical peak value of floating-point calculation. The method could port Linux OS to the target board successfully and can be used on other platforms. The research has great significance to the development of the domestic Loongson processor and the cc-NUMA platform based on Loongson processors. © 2013 Springer science+Business Media New York.

关键词： Program processors

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Shedder: A metadata sharing management method across multi-clusters

Shedder: A metadata sharing management method across multi-c...

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13th International Conference on Algorithms and Architectures for Parallel Processing, ICA3PP 2013

作者： Hao, Qinfen Zhong, Qianqian Ruan, Li Zhang, Zhenzhong Xiao, Limin State Key Laboratory of Software Development Environment Beihang University Beijing 100191 China School of Computer Science and Engineering Beihang University Beijing 100191 China

ISBN: (纸本)9783319038582

With the increase of large number of data, multi-clusters structure has been adopted for data storage. Therefore, the demand for file metadata sharing across global scale clusters is quickly rising. However, today's software can not provide features to reflect these desires well. In this paper, We propose and develop a metadata sharing management method called Shedder. First Shedder can allow customized multi-clusters metadata sharing structure. Next, Shedder can provide highly efficient global synchronization for all clusters. Finally, Shedder allows customized user view generated from global namespace. Our evaluation for Shedder shows that Shedder provides low latency for global synchronization. Dynamic transformation from global namespace to customized user view also has low time cost for different size of workloads. © Springer International Publishing Switzerland 2013.

关键词： Digital storage

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Accelerate demodulation of quadrature amplitude modulation using GPU

Accelerate demodulation of quadrature amplitude modulation u...

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2013 2nd International Conference on Manufacturing engineering and Process, ICMEP 2013

作者： Gao, Xiao Peng Wang, Si Yuan Wan, Han State Key Laboratory of Software Development Environment School of Computer Science and Engineering Beihang University Xueyuan Road No.37 Haidian District Beijing China

ISBN: (纸本)9783037857076

Quadrature amplitude modulation (QAM) is widely used in communication systems. The traditional QAM demodulation method was implemented in hardware. This paper proposes a demodulation algorithm using GPU. The GPU algorithm is easier to add new features than hardware implementation and reaches 57x speed up compared with the serial algorithm on CPU. It is shown that the QAM demodulation algorithm gained significant performance increase due to the natural parallism of the GPU, using Compute Unified Device Architecture (CUDA). © (2013) Trans Tech Publications, Switzerland.

关键词： Quadrature amplitude modulation

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A DNA computing system of modular-multiplication over finite field GF(2n)

A DNA computing system of modular-multiplication over finite...

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13th International Conference on Algorithms and Architectures for Parallel Processing, ICA3PP 2013

作者： Li, Yongnan Xiao, Limin Ruan, Li Zhang, Zhenzhong Li, Deguo State Key Laboratory of Software Development Environment Beihang University Beijing 100191 China School of Computer Science and Engineering Beihang University Beijing 100191 China

ISBN: (纸本)9783319038582

The enormous parallel computing ability and high memory density of DNA computing bring potential challenges and opportunities to traditional cryptography. Finite field GF(2n) is one of the most commonly used mathematic sets for cryptography. It is an open problem that how to implement the arithmetic operations over finite field GF(2n) based on DNA computing. Existing research has the problem that the lengths of parameters in the DNA tile assembly process could not match each other strictly. This paper proposes a parallel molecular computing system to compute the modular-multiplication, an operation combining multiplication and reduction over finite field GF(2n). The multiplication and the reduction are executed simultaneously in this system. One concrete example of 1100 · 1001 mod 10011 is proposed to show the details of our tile assembly system. The time complexity of this system is Θ(n) and the space complexity is Θ(n2). This system requires 210 types of computation tiles and 17 types of boundary tiles. © Springer International Publishing Switzerland 2013.

关键词： Cryptography

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Locating and understanding concurrency bugs based on edge-labeled communication graphs 25

Locating and understanding concurrency bugs based on edge-la...

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25th International Conference on software engineering and Knowledge engineering, SEKE 2013

作者： Li, He Lin, Mengxiang Jameel, Tahir Jiang, Zhenyuan State Key Laboratory of Software Development Environment Beihang University Beijing China School of Computer Science and Engineering Beihang University China School of Mechanical Engineering and Automation Beihang University China

ISBN: (纸本)1891706330

Concurrency bugs are difficult to locate and understand. This paper presents LUCON, a novel edge-labeled communication graph based technique, which locates the concurrency bugs and presents buggy access patterns and bug triggering scenarios to help programmers understand the bugs. The buggy access pattern gives the essence of the bug and the bug triggering scenario shows how the bug happens with the information of call stack and thread creation. A set of experimental studies have been conducted to evaluate the effectiveness of LUCON. The preliminary results show that LUCON can locate concurrency bugs accurately and the bug reports provided by LUCON can really help programmers understand the bugs. Copyright © 2013 by Knowledge Systems Institute Graduate school.

关键词： Graphic methods

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