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4th International Symposium on Leveraging Applications, ISoLA 2010

作者： Qian, Li Jianhua, Zhao Xuandong, Li State Key Laboratory of Novel Software Technology of China Nanjing University 210093 Nanjing China Department of Computer Science and Technology Nanjing University 210093 Nanjing China

ISBN: (纸本)3642165575

This paper presents an efficient context-sensitive, field-based Andersen-style points-to analysis algorithm for Java programs. This algorithm first summarizes methods of the program under analysis using directed graphs. Then it performs local circle elimination on these summary graphs to reduce their sizes. The main analysis algorithm uses these graphs to construct the main points-to graph. Topological sort and cycle-elimination is performed on the nodes of both main points-to graphs and summary graphs to speed up the transitive closure computation on the main points-to graph. A suite of Java program benchmarks are used to demonstrate the efficiency of our algorithm. © 2010 Springer-Verlag.

关键词： Directed graphs

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Preserving data flow correctness in process adaptation

Preserving data flow correctness in process adaptation

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2010 IEEE 7th International Conference on Services Computing, SCC 2010

作者： Song, Wei Ma, Xiaoxing Cheung, S.C. Hu, Hao Lü, Jian State Key Laboratory for Novel Software Technology Nanjing University Nanjing China Department of Computer Science and Engineering HKUST Hongkong Hong Kong

ISBN: (纸本)9780769541266

In services and cloud computing, processes need to be continually adapted to changing environments and requirements. Undisciplined process adaptation could easily lead to data flow anomalies, e.g., input missing for some activities in the process. In this paper, we study the problem of data-flow-correctness-preserving adaptation and propose three important criteria that can maintain the data flow correctness in process adaptation. We demonstrate our approach by using a typical process adaptation scenario in BPEL. © 2010 IEEE.

关键词： Data transfer

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Perturbing numerical calculations for statistical analysis of floating-point program (in)stability 10

Perturbing numerical calculations for statistical analysis o...

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19th International Symposium on software Testing and Analysis, ISSTA 2010

作者： Tang, Enyi Barr, Earl Li, Xuandong Su, Zhendong State Key Laboratory for Novel Software Technology Nanjing University Nanjing China Department of Computer Science University of California Davis United States

ISBN: (纸本)9781605588230

Writing reliable software is difficult. It becomes even more difficult when writing scientific software involving floating-point numbers. computers provide numbers with limited precision;when confronted with a real whose precision exceeds that limit, they introduce approximation and error. Numerical analysts have developed sophisticated mathematical techniques for performing error and stability analysis of numerical algorithms. However, these are generally not accessible to application programmers or scientists who often do not have in-depth training in numerical analysis and who thus need more automated techniques to analyze their code. In this paper, we develop a novel, practical technique to help application programmers (or even numerical experts) obtain high-level information regarding the numerical stability and accuracy of their code. Our main insight is that by systematically altering (or perturbing) the underlying numerical calculation, we can uncover potential pitfalls in the numerical code. We propose two complementary perturbations to statistically measure numerical stability: value perturbation and expression perturbation. Value perturbation dynamically replaces the least significant bits of each floating-point value, including intermediate values, with random bits to statistically induce numerical error in the code. Expression perturbation statically changes the numerical expressions in the user program to mathematically equivalent (in the reals, likely not in floating-point numbers), but syntactically different forms. We then compare the executions of these "equivalent" forms to help discover and remedy potential instabilities. Value perturbation can overstate error, while expression perturbation is relatively conservative, so we use value perturbation to generate candidates for expression perturbation. We have implemented our technique, and evaluation results on various programs from the literature and the GNU Scientific Library (GSL) show that our te

关键词： Stability

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Analyzing the robustness of FTSP with timed automata 10

Analyzing the robustness of FTSP with timed automata

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Proceedings of the Second Asia-Pacific Symposium on Internetware

作者： Tan, Lin Bu, Lei Zhao, Jianhua Wang, Linzhang State Key Laboratory of Novel Software Technology Nanjing University Nanjing Jiangsu 210093 China Department of Computer Science and Technology Nanjing University Nanjing Jiangsu 210093 China

ISBN: (纸本)9781450306942

Since Wireless Sensor Networks (WSNs) are increasingly used in many industrial and civilian application areas, the correctness of their low level protocol such as the Flooding Time Synchronization Protocol (FTSP) is critical. However ensuring such correctness is difficult because of the complexity of the runtime environment. Model checking is an effective method for this problem, since it is a formal verification approach which has an advantage in exploring all behaviors of the system and discovering subtle errors. In this paper, we present a novel timed automaton model for FTSP. The main insight of our method is that by using timed automata, we can introduce the transmission delay and node failures that exist in real WSNs into our model and check whether FTSP is robust to node failures under a more realistic environment. We generate the timed automata models of FTSP and verify them by the model checking tool UPPAAL. Our evaluation result depicts an error of FTSP when the algorithm runs in the scenario that two root nodes fail continuously.

关键词： Model checking

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Research on the adaptable reputation-based scheduling for storage resources in data grids

Research on the adaptable reputation-based scheduling for st...

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International Conference on Internet technology and Applications, ITAP 2010

作者： Liu, Wei Huang, Xun Du, Wei Department of Computer Science Wuhan University of Technology Wuhan 430063 China State Key Lab. of Software Engineering Wuhan University Wuhan 430072 China China State Key Laboratory for Novel Software Technology Nanjing University Nanjing 210093 China Institute of Computer Science Huazhong University of Science and Technology Wuhan 430074 China

ISBN: (纸本)9781424451432

Data grids provide the data-intensive applications with a large virtual stroage framework. We use a reputation-based trust aggregation approach for data providers to quantitatively predict and calculate whether or not they are reliable and credible. In the same time, adaptable trust service is increasingly important for applications running on data grids. However, existing systems are unable to satisfy the flexible trust needs of complex data-intensive applications. This paper introduced a novel approach and proposed a quality of reputation-based trust framework for storage resources in data grids (QRTF). QRTF leverages the manager to dynamically control quality of trust for application requests, thereby achieving good tradeoffs between reputation-based trust service and system performance. Experimental results based on a simulated grid with storage resources show that the proposed framework is capable of significantly improving trust service quality and guaranteeing desired response time. ©2010 IEEE.

关键词： Digital storage

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Composite surface generation from sketchy drawing

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Jisuanji Fuzhu Sheji Yu Tuxingxue Xuebao/Journal of computer-Aided Design and computer Graphics 2010年第6期22卷 907-913页

作者： Liu, Kai Sun, Zhengxing Zhang, Yaoye State Key Laboratory for Novel Software Technology Department of Computer Science and Technology Nanjing University Nanjing 210093 China

To facilitate designers to create and or modify 3D shapes rapidly during prototype modeling, this paper presents an online interactive approach which can easily generate 3D composite surface of various shapes. The approach incorporates the sketch-based interface into the construction of variational implicit surface. It infers 3D surface constraint points from 2D drawing strokes (including contour stroke, cross-section stroke and skeleton stroke) using inflation transformation, cross transformation and bend transformation respectively, users can then control the shapes of 3D surfaces with freehand sketches. A technique of localization of variational implicit function is adopted for real time surface blending. Experiment results show that the proposed method supports the "divide-and-conquer" construction process of composite surface efficiently.

关键词：手绘草图交互三维曲面建模变分隐式曲面参数曲线曲面混合

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Study language models with specific user goals 10

Study language models with specific user goals

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19th International World Wide Web Conference, WWW2010

作者： Cen, Rongwei Liu, Yiqun Zhang, Min Ru, Liyun Ma, Shaoping State Key Laboratory of Intelligent Technology and Systems Department of Computer Science and Technology Tsinghua University Beijing 100084 China

ISBN: (纸本)9781605587998

Under different language contexts, people choose different terms or phrases to express their feelings and opinions. When a user is writing a paper or chatting with a friend, he/she applies a specific language model corresponding to the underlying goal. This paper presents a log-based study of analyzing the language models with specific goals. We exhibit the statistical information of terms and software programs, propose some methods to estimate the divergence of language models with specific user goals and measure the discrimination of these models. Experimental results show that the language models with different user goals have large divergence and different discrimination. These study conclusions can be applied to understand user needs and improve Human-computer Interaction (HCI). © 2010 Copyright is held by the author/owner(s).

关键词： Computational linguistics

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Isolating suspiciousness from spectrum-based fault localization techniques

Isolating suspiciousness from spectrum-based fault localizat...

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10th International Conference on Quality software, QSIC 2010

作者： Xie, Xiaoyuan Chen, Tsong Yueh Xu, Baowen Centre for Software Analysis and Testing Swinburne University of Technology Hawthorn VIC 3122 Australia School of Computer Science and Engineering Southeast University Nanjing 210096 China Department of Computer Science and Technology State Key Laboratory for Novel Software Technology Nanjing University Nanjing 210093 China

ISBN: (纸本)9780769541310

Spectrum-based fault localization (SBFL) is one of the most promising fault localization approaches, which normally uses the failed and passed program spectrum to evaluate the risks for all program entities. However, it does not explicitly distinguish the different degree in definiteness between the information associated with the failed spectrum and the passed spectrum, which may result in an unreliable location of faults. Thus in this paper, we propose a refinement method to improve the accuracy of the predication by SBFL, through eliminating the indefinite information. Our method categorizes all statements into two groups according to their different suspiciousness, and then uses different evaluation schemes for these two groups. In this way, we can reduce the use of the unreliable information in the ranking list, and finally provide a more precise result. Experimental study shows that for some SBFL techniques, our method can significantly improve their performance in some situations, and in other cases, it can still remain the techniques' original performance. © 2010 IEEE.

关键词： Program debugging

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Modeling users' visiting behaviors for Web load testing by Continuous Time Markov Chain

Modeling users' visiting behaviors for Web load testing by C...

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7th Web Information Systems and Applications Conference, WISA 2010, 5th Workshop on Semantic Web and Ontology, SWON 2010, 4th Workshop on Electronic Government technology and Application, EGTA 2010

作者： Xu, Lei Zhang, Weifeng Chen, Lianjie Department of Computer Science and Technology Nanjing University State Key Laboratory for Novel Software Technology Nanjing China School of Computer Nanjing University of Posts and Telecommunications Nanjing China School of Computer Science and Engineering Southeast University Nanjing China

ISBN: (纸本)9780769541938

Virtual users with high quality are the preconditions to ensure the effect of load testing for Web applications. The existed tools for load testing usually generate virtual users with randomly choosing user sessions, manually generating user sessions or mining Log files, which causing such problems as non-real workload, subjectivity or difficult to update. Therefore we set each virtual user with a corresponding configure file, and these files determine the visiting paths, visiting moments and stay time of virtual users based on the Continuous Time Markov Chain. So we firstly finish the pretreatment for Log files, then construct the user visiting model, and next generate the virtual users, lastly carry out the load testing. In this way, we can obtain more reliable results for Web application load testing than the existed methods. © 2010 IEEE.

关键词： Load testing

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DREAM: On the reaction delay in large scale wireless networks with mobile sensors

DREAM: On the reaction delay in large scale wireless network...

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2010 IEEE 18th International Workshop on Quality of Service, IWQoS 2010

作者： Tang, Shao Jie Li, Xiang-Yang Yuan, Jing Wang, Cheng Chen, Gui Hai Jiang, Changjun Department of Computer Science Illinois Institute of Technology Chicago IL 60616 United States State Key Laboratory of Novel Software Technology NanJing University NanJing China Department of Computer Science Tongji University China Institute of Computer Application Technology Hangzhou Dianzi University China

ISBN: (纸本)9781424459889

In this work, we present a monitor and rescue system utilizing hybrid networks which is a integration of stationary sensor networks and mobile sensor networks: stationary sensor networks comprised of large numbers of small, simple, and inexpensive wireless sensors, and the mobile sensor network contains a set of mobile sensors (robots). The static sensors in our network have "monitoring" ability, i.e., any activated static sensor can detect the event as long as its sensing range intersects the event region. And the mobile sensors have "moving" and "rescuing" ability, e.g., they can move toward the event region with limited speed and further perform certain rescuing/processing operations on the event. We can consider the event as a hazard, e.g., wild fire, and the mobile sensors as fireman robots. As soon as the fire is detected by the static sensors, the fireman robots are expected to move from its initial location to the hazard region within minimum latency. We define the reaction delay of the system as the delay from the occurrence of event till at least one mobile sensor reaches the event. In order to satisfy certain reaction delay requirement while minimizing the total cost, we propose a number of deployment strategies for the stationary sensor network and mobile sensor network respectively. We further design a random wake-up scheduling for the static sensors for the sake of energy efficiency. Finally, we propose a pure distributed motion strategy for mobile sensors without reliance on localization services such as GPS, focusing on simple algorithms for distributed decision making and information propagation. We demonstrate the efficacy of our system in simulation, providing empirical results. keywords-Sensor networks, mobility, detection, delay.

关键词： Robots

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