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Loop reduction techniques for reachability analysis of linear hybrid automata

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Science china(Information Sciences) 2012年第12期55卷 2663-2674页

作者： PAN MinXue,LI You,BU Lei & LI XuanDong state key laboratory for novel software technology,Department of Computer Science and technology,nanjing University,nanjing 2.0093.china 1. state key laboratory for novel software technology Department of Computer Science and Technology Nanjing University Nanjing 210093 China

The problem of reachability analysis of linear hybrid automata(LHA) is very *** paper considers to improve the efficiency of the reachability analysis by optimizing the structures of *** identify two types of loops called the flexible loops and the zero loops,and present the techniques to replace the repetitions of those loops in the behavior of LHA with finite sequences of locations and in the meantime simplify the associated *** techniques work not only for the polyhedral computing based algorithms but also for the bounded model checkers.

关键词： real-time and hybrid systems linear hybrid automata reachability analysis

Exploiting remote learners in Internet environment with agents

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Science china(Information Sciences) 2010年第1期53卷 64-76页

作者： LI Ming, WANG Wei & ZHOU ZhiHua National key laboratory for novel software technology, nanjing University, nanjing 2.0093. china 1. National key laboratory for novel software technology Nanjing University Nanjing 210093 China

Data in the Internet are scattered on different sites indeliberately, and accumulated and updated frequently but not synchronously. It is infeasible to collect all the data together to train a global learner for prediction; even exchanging learners trained on different sites is costly. In this paper, aggregative-learning is proposed. In this paradigm, every site maintains a local learner trained from its own data. Upon receiving a request for prediction, an aggregative-learner at a local site activates and sends out many mobile agents taking the request to potential remote learners. The prediction of the aggregative-learner is made by combining the local prediction and the responses brought back by the agents. Theoretical analysis and simulation experiments show the superiority of the proposed method.

关键词： machine learning data mining aggregative-learning mobile agent Internet environment

Comparing logic coverage criteria on test case prioritization

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Science china(Information Sciences) 2012年第12期55卷 2826-2840页

作者： FANG ChunRong 1,2,CHEN ZhenYu 1,2 & XU BaoWen 1 1 state key laboratory for novel software technology,nanjing University,nanjing 2.0093.china 2 software Institute,nanjing University,nanjing 2.0093.china 1. state key laboratory for novel software technology Nanjing University Nanjing 210093 China2. Software Institute Nanjing University Nanjing 210093 China

Logic coverage criteria have been widely used in the testing of safety-critical *** the past few years,fault-based logic coverage criteria have been studied intensively both in theory and in ***,there is a lack of authentic evidence of the comparison of fault-based logic coverage criteria with other logic coverage criteria,such as branch coverage and modified condition/decision coverage(MC/DC).In this paper,we present a comprehensive empirical study that compares these logic coverage criteria on test case prioritization,which is currently a hot topic in software *** useful conclusions are drawn from our research:(1) Fine-grained coverage criteria are always more effective and efficient.(2) The effectiveness of fault-based logic coverage criteria is not significantly different from that of MC/DC in terms of statistics,but the former is more stable.(3) A random strategy is more effective than branch coverage if a certain number of test cases are redundant.

关键词： fault detection capability logic coverage fault-based testing test case prioritization

Technical framework for Internetware: An architecture centric approach

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Science in china(Series F) 2008年第6期51卷 610-622页

作者： YANG FuQing1,2, Lü Jian3,4 & MEI Hong1,2 1 key laboratory of High Confidence software Technologies (Peking University), Ministry of Education, Beijing 100871, china 2 School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, china 3.state key laboratory for novel software technology, nanjing 2.0093. china 4 Department of Computer Science and technology, nanjing University, nanjing 2.0093. china 1. key laboratory of High Confidence software Technologies (Peking University) Ministry of Education Beijing 100871 China 2. School of Electronics Engineering and Computer Science Peking University Beijing 100871 China 3. state key laboratory for novel software technology Nanjing 210093 China 4. Department of Computer Science and technology Nanjing University Nanjing 210093 China

Being a new software paradigm evolved by the Internet, Internetware brings many challenges to the traditional software methods and techniques. Sponsored by the national basic research program （973）, researchers in china have developed an architecture centric technical framework for the definition, incarnation and engineering of Internetware. First of all, a software model for Internetware is defined for what to be, including that Internetware entities should be packaged as components, behaving as agents, interoperating as services, collaborating in a structured and on demand manner, etc. Secondly, a middleware for Internetware is designed and implemented for how to be, including that Internetware entities are incarnated by runtime containers, structured collaborations are enabled by runtime software architecture, Internetware can be managed in a reflective and autonomic manner, etc. Thirdly, an engineering methodology for Internetware is proposed for how to do, including the way to develop Internetware entities and their collaborations by transforming and refining a set of software architectures which cover all the phases of software lifecycle, the way to identify and organize the disordered software assets by domain modeling, etc.

关键词： Internetware component software architecture agent middleware

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Contourlet HMT model with directional feature

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Science china(Information Sciences) 2012年第7期55卷 1563-1578页

作者： WANG XiangHai 1,2,3 ,CHEN MingYing 1 ,SONG ChuanMing 1,2 ,XU MengChun 1 & FANG LingLing 3 1 College of Computer and Information technology,Liaoning Normal University,Dalian 116029,china 2 state key laboratory for novel software technology,nanjing University,nanjing 2.0093.china 3 Provincial key laboratory for Computer Information Processing technology,Soochow University,Suzhou 215006,china 1. College of Computer and Information technology Liaoning Normal University Dalian 116029 China2. State Key Laboratory for Novel Software Technology Nanjing University Nanjing 210093 China3. Provincial Key Laboratory for Computer Information Processing Technology Soochow University Suzhou 215006 China

According to Shanno's information theory,the directional feature of texture is defined as the value of directional variable when an image signal attains a singularity of random *** terms of this definition,we calculate the texture's directional features using Tamura's method and study the directional probability distribution of Contourlet *** we find that the directional features tend to be conveyed across parent and child *** on this conclusion,we establish a novel probability distribution model of hidden direction variables under the condition of hidden state variable's distribution,named Contourlet HMT model with directional *** structure and training method of the model are presented as ***,an unsupervised context-based image segmentation algorithm is proposed on the basis of the proposed *** effectiveness is verified via extensive experiments carried out on several synthesized images and remote sensing images.

关键词： directional feature Contourlet HMT Contourlet HMT with directional feature unsupervised texture segmentation

The optimization of replica distribution in the unstructured overlays

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Science china(Information Sciences) 2012年第3期55卷 714-722页

作者： FENG GuoFu1,2 , LI WenZhong2, LU SangLu2, CHEN DaoXu2 & BUYYA Rajkumar3 1School of Information Science, nanjing Audit University, nanjing 210029, china 2state key laboratory of novel software technology, nanjing University, nanjing 2.0093. china 3Department of Computer Science and software Engineering, The University of Melbourne, Victoria 3010, Australia 1. School of Information Science Nanjing Audit University Nanjing 210029 China2. State Key Laboratory of Novel Software Technology Nanjing University Nanjing 210093 China3. Department of Computer Science and Software Engineering The University of Melbourne Victoria 3010 Australia

Replication is a widely used technique in unstructured overlays to improve content availability or system performance. A fundamental question often addressed by previous work focused on: how many replicas ought to be allocated for each data item given the fixed query rates and limited storage capability? In this paper, we have put forth two optimal replica distributions to achieve the highest success rate and the lowest message consumption. Especially, we have investigated the influence of item size on replica distribution. Our results show that Square-Root Replication, which is traditionally considered to be optimal, is not always the best choice. Our study offers a new deep understanding of resource managment in self-organized unstructured overlays.

关键词： unstructured overlay item size distribution query rate success rate expected search size

An algorithm to compute maximal contractions for Horn clauses

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Science china(Information Sciences) 2011年第2期54卷 244-257页

作者： LUO Jie & LI Wei state key laboratory of software Development Environment, School of Computer Science and technology, Beihang University, Beijing 100191, china 1. state key laboratory of software Development Environment School of Computer Science and Technology Beihang University Beijing 100191 China

In the theory of belief revision, the computation of all maximal subsets (maximal contractions) of a formula set with respect to a set of facts is one of the key problems. In this paper, we try to solve this problem by studying the algorithm to compute all maximal contractions for Horn clauses. First, we point out and prove the conversion relationship between minimal inconsistent subsets of union of the formula set and the set of facts and maximal contractions of the formula set with respect to the set of facts. Second, we prove a necessary condition of a set of Horn clauses to be minimal inconsistent. Then, based on these two conclusions, we propose an interactive algorithm to enumerate all minimal inconsistent subsets of a given set of Horn clauses and a second algorithm to compute maximal contractions from these minimal inconsistent subsets. Finally, we proposed an interactive algorithm to compute maximal contractions for Horn clauses by composing the above two algorithms.

关键词： maximal contraction minimal inconsistent set minimal subtraction Horn clause

Evolution of Bright Screening-photovoltaic Spatial Optical Solitons

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Chinese Journal of Lasers 2001年第5期10卷 28-33页

作者： LIU Jinsong (state key laboratory of Laser technology, Huazhong University of Science and technology, Wuhan 430074, china) 华中科技大学激光技术国家重点实验室湖北武汉

A numerical analysis of the dynamical evolution of bright screening photovoltaic (SP) spatial solitons in biased photovoltaic photorefractive materials in the case of neglecting the material loss and the diffusion is presented. When an incident optical beam is a bright SP soliton, the beam propagates along a linear path with its shape kept unchanged. When the incident optical beam is slightly different from a bright SP soliton, the beam reshapes itself and tries to evolve into a bright SP soliton after a short distance. However, when the incident optical beam is significantly different from a SP bright soliton, the beam cannot evolve into a stable bright SP soliton, and tends to experience periodic compression and expansion. For a low intensity input beam, the wave experiences a periodic process of compression first and then expansion during the initial part of the cycle. For a high intensity input beam, however, the wave will initially diffract and then experiences compression during the cycle.

关键词： nonlinear optics spatial optical solitons photorefractive effects

Theoretical observation of hexaatomic molecules containing pentacoordinate planar carbon

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Science china Chemistry 2008年第11期51卷 1030-1035页

作者： LUO Qiong state key laboratory of Explosion Science and technology, Beijing Institute of technology, Beijing 100081, china 1. state key laboratory of Explosion Science and technology Beijing Institute of Technology Beijing 100081 China

The smallest molecules up to date containing a D5h pentacoordinate planar carbon (PPC) atom, CBe5 and CBe54-, are presented by means of ab initio calculations. To gain a better understanding about which electronic factors contribute to their stabilization, natural bond orbital (NBO) analysis and the nucleus independent chemical shifts (NICS) were calculated. The data reported here suggest that D5h CBe5 is σ aromaticity in nature, while in D5h CBe54- π aromaticity is dominating. The classical octet rule is well satisfied in both molecules, and is one of the fundamental reasons to understand the stability of the pentagon structures. The Be5 ring serves as σ donor in D5h CBe5, and π-acceptor in D5h CBe54-. The D5h CBe54- possessing 18 valence electrons with a closed-shell electron configuration is the most plau-sible candidate for experimental detection.

关键词： pentacoordinate planar carbon Be5 ring ab initio

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