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IEEE International Conference on High Performance Computing and Communication

作者： Yang, Chao Zhang, Yunquan Li, Ligang Institute of Software Chinese Academy of Sciences Beijing 100190 China State Key Lab. of Computer Science Chinese Academy of Sciences Beijing 100190 China Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China

ISBN: (纸本)9780769542140

Large-scale simulation of the thermal convection in the Earth's outer core is studied. Starting from a legacy parallel code using Aztec and MPI, two optimized codes have been developed based on the PETSc software package. The first version gains several times acceleration with the help of the block-Jacobi preconditioners and the well-optimized libraries provided in PETSc. The second version, aiming at better parallel scalab.lity, is developed based on the ideas of domain decomposition method for multi-physical problems. Test results employing thousands of processor cores on three supercomputers, i.e., an IBM BlueGene/L, a Dawning 5000A and a Lenovo DeepComp 7000, are provided. © 2010 IEEE.

关键词： Multiphysics

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Formally Verified C Code Generation from Hybrid Communicating Sequential Processes

arXiv

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arXiv 2024年

作者： Wang, Shuling Ji, Zekun Zhan, Bohua Xu, Xiong Gao, Qiang Zhan, Naijun State Key Lab. of Computer Science Institute of Software Chinese Academy of Sciences Beijing China

Hybrid Communicating Sequential Processes (HCSP) is a formal model for hybrid systems, including primitives for evolution along an ordinary differential equation (ODE), communication, and parallel composition. Code generation is needed to convert HCSP models into code that can be executed in practice, and the correctness of this conversion is essential to ensure that the generated code accurately reflects the formal model. In this paper, we propose a code generation algorithm from HCSP to C with POSIX library for concurrency. The main difficulties include how to bridge the gap between the synchronized communication model in HCSP and the use of mutexes for synchronization in C, and how to discretize evolution along ODEs and support interrupt of ODE evolution by communication. To prove the correctness of code generation, we define a formal semantics for POSIX C, and build transition system models for both HCSP and C programs. We then define an approximate bisimulation relation between traces of transition systems, and show that under certain robustness conditions for HCSP, the generated C program is approximately bisimilar to the original model. Finally, we evaluate the code generation algorithm on a detailed model for automatic cruise control, showing its utility on real-world examples. Copyright © 2024, The Authors. All rights reserved.

关键词： Hybrid systems

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A New Framework for Bounding Reachability Probabilities of Continuous-time Stochastic systems

arXiv

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arXiv 2023年

作者： Xue, Bai State Key Lab. of Computer Science Institute of Software Chinese Academy of Sciences Beijing China

This manuscript presents an innovative framework for constructing barrier functions to bound reachability probabilities for continuous-time stochastic systems described by stochastic differential equations (SDEs). The reachability probabilities considered in this paper encompass two aspects: the probability of reaching a set of specified states within a predefined finite time horizon, and the probability of reaching a set of specified states at a particular time instant. The barrier functions presented in this manuscript are developed either by relaxing a parabolic partial differential equation that characterizes the exact reachability probability or by applying the Grönwall's inequality. In comparison to the prevailing construction method, which relies on Doob's non-negative supermartingale inequality (or Ville's inequality), the proposed barrier functions provide stronger alternatives, complement existing methods, or fill gaps. Copyright © 2023, The Authors. All rights reserved.

关键词： Stochastic systems

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Image semantic description and automatic semantic annotation

Image semantic description and automatic semantic annotation

引用

作者： Liang, Meiyu Du, Junping Jia, Yingmin Sun, Zengqi Beijing Key Lab. of Intelligent Telecommunication Software and Multimedia School of Computer Science Beijing University of Posts and Telecommunications Beijing China Beijing China Department of Computer Science Tsinghua University Beijing China

ISBN: (纸本)9781424474530

Making the semantic description and automatic semantic annotation of the image which contains rich contents and intuitive expression is a research subject that is challenging. It is a key technology of realizing fast and effective image retrieval and a research focusing on cross media mining. Also it has great application value in various kinds of fields. This paper studies and discusses image media semantic description and automatic semantic annotation. By extracting SIFT visual features, we make the description of the image semantic, then establish the association between local image visual features and semantic keywords, and finally realize the image to the text feature mapping and the automatic semantic annotation. The simulation experiment result shows that this method can accomplish the image automatic semantic annotation efficiently, and also it can reach a higher accuracy. ©ICROS.

关键词： Image retrieval

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Identifying CpG islands in genome using conditional random fields

Identifying CpG islands in genome using conditional random f...

引用

8th International Conference on Intelligent Computing Technology, ICIC 2012

作者： Liu, Wei Chen, Hanwu Chen, Ling Department of Computer Science and Engineering Southeast University Nanjing 210096 China Department of Computer Science Yangzhou University Yangzhou 225127 China National Key Lab. of Novel Software Tech. Nanjing University Nanjing 210093 China

ISBN: (纸本)9783642315879

This paper presents a novel method for CpG islands location identification based on conditional random fields (CRF) model. The method transforms CpG islands location identification into the problem of sequential data lab.ling. Based on the nature of CpG islands location, we design the methods of model constructing, training and decoding in CRF accordingly. Experimental results on benchmark data sets show that our algorithm is more practicable and efficient than the traditional methods. © 2012 Springer-Verlag.

关键词： Location

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An interface model of software components

An interface model of software components

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10th International Colloquium on Theoretical Aspects of Computing, ICTAC 2013

作者： Dong, Ruzhen Zhan, Naijun Zhao, Liang Dipartmento di Informatica Università di Pisa Italy UNU-IIST China State Key Lab. of Computer Science Institute of Software Chinese Academy of Sciences China Institute of Computing Theory and Technology Xidian University China

ISBN: (纸本)9783642397172

We present an automata-based model for describing the behaviors of software components. This extends our previous work by allowing internal behaviors. In order to improve the techniques for checking if two component can be composed without causing deadlocks, we develop an interface model, called input deterministic automata, that define all the non-blockable traces of invocation to services provided by a component. We also present an algorithm that, for any given component automaton, generates the interface model that has the same input deterministic behaviors as the original automaton. Properties of the algorithm with respect to component refinement and composition are studied as preliminary results towards a theory of software component interfaces. © 2013 Springer-Verlag Berlin Heidelberg.

关键词： Automata theory

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On sweep coverage with minimum mobile sensors

On sweep coverage with minimum mobile sensors

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16th IEEE International Conference on Parallel and Distributed systems, ICPADS 2010

作者： Du, Junzhao Li, Yawei Liu, Hui Sha, Kewei Software Engineering Institute Xidian University Xi'an ShaanXi China State Key Lab. of ISN Xidian University Xi'an ShaanXi China Department of Computer Science Oklahoma City University Oklahoma City OK United States

ISBN: (纸本)9780769543079

For some sensor network applications, the problem of sweep coverage, which periodically covers POIs (Points of Interest) to sense events, is of importance. How to schedule minimum number of mobile sensors to achieve the sweep coverage within specified sweep period is a challenging problem, especially when the POIs to be scanned exceeds certain scale and the speed of mobile sensor is limited. Therefore, multiple mobile sensors are required to collab.ratively complete the scanning task. When the mobile sensor is restricted to follow the same trajectory in different sweep periods, we design a centralized algorithm, MinExpand, to schedule the scan path. When the scan path of the existing mobile sensors has been exceeds the length constraint, MinExpand gradually deploys more mobile sensors and eventually achieves sweep coverage to all POIs. When the mobile sensors are not restricted to follow the same trajectory in different sweep periods, we design OSweep algorithm, where all the mobile sensors are scheduled to move along a TSP (Traveling Salesman Problem) ring consists of POIs. We conduct comprehensive simulations to study the performance of the proposed algorithms. The simulation results show that MinExpand and OSweep outperform CSWEEP in both effectiveness and efficiency. © 2010 IEEE.

关键词： Wireless sensor networks

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Sleep-wakeup algorithms for virtual barriers of wireless sensor networks in 3D space

Sleep-wakeup algorithms for virtual barriers of wireless sen...

引用

International Conference on Mobile Ad-hoc and Sensor Networks

作者： Du, Junzhao Liu, Chang Liu, Hui Sha, Kewei Software Engineering Institute Xidian University Xi'an ShaanXi China State Key Lab. of ISN Xidian University Xi'an ShaanXi China Department of Computer Science Oklahoma City University Oklahoma City OK United States

ISBN: (纸本)9780769543154

In order to maximize the lifetime of wireless sensor networks, while ensuring the monitoring quality for specific applications, we develop the sleep-wakeup algorithms for the sensor networks. Firstly, for the three-dimensional wireless sensor networks, we formulate the virtual barrier coverage problems. Secondly, the design and implementation of the nodes sleep-wakeup scheduling algorithm, FWP, to maximize the covering time of a single virtual barrier and the k-virtual barriers sleep-wakeup scheduling algorithm, OBP, to maximize the network coverage time of k virtual barriers are presented. Finally, through the comprehensive simulation, the effectiveness of the algorithms is validated. The relationships among the density of the virtual barriers, virtual lattice point, the number of sensors and the sensing radius are also investigated and simulated. © 2010 IEEE.

关键词： Wireless sensor networks

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Flow based clustering algorithm for tourism search engine

Flow based clustering algorithm for tourism search engine

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作者： Liu, Jie Du, Junping Sun, Zengqi Jia, Yingming Beijing Key Lab. of Intelligent Telecommunication Software and Multimedia School of Computer Science Beijing University of Posts and Telecommunications Beijing China Department of Computer Science Tsinghua University Beijing China Beijing China

ISBN: (纸本)9781424474530

This paper introduces a flow based clustering algorithm for tourism search engine. Unlike the general tourism search engines such as ***, *** and *** etc. to return the users' queries huge amount of web page links, this algorithm helps the tourism search engine create a list of words which serve as suggestions to expand and update the users' queries. It is much different from the previous clustering algorithms which cluster the results by the similar subjects. This algorithm clusters the search results by the inside vector distance representing each relationship between the web pages. In this manner, these representatives belong to different clusters merging into something like different flows. The experimental results indicate that the algorithm performs an unexpected usefulness for the users' queries. Meanwhile, through the comparison with some often used algorithms and an online survey, it shows this algorithm has an accepted performance. ©ICROS.

关键词： Search engines

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Collab.rative Reversing of Input Formats and Program Data Structures for Security Applications

引用

China Communications 2014年第9期11卷 135-147页

作者： ZHAO Lei Key Laboratory of Aerospace Information Security and Trust Computing Wuhan China Computer School of Wuhan University Wuhan China State Key Lab. for Novel Software Technology Nanjing University China

Reversing the syntactic format of program inputs and data structures in binaries plays a vital role for understanding program behaviors in many security *** this paper,we propose a collab.rative reversing technique by capturing the mapping relationship between input fields and program data *** key insight behind our paper is that program uses corresponding data structures as references to parse and access different input fields,and every field could be identified by reversing its corresponding data *** details,we use a finegrained dynamic taint analysis to monitor the propagation of *** identifying base pointers for each input byte,we could reverse data structures and conversely identify fields based on their referencing data *** construct several experiments to evaluate the *** results show that our approach could effectively reverse precise input formats,and provide unique benefits to two representative security applications,exploit diagnosis and malware analysis.

关键词： software security, reversingengineering fine-grained dynamic tainting

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