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What are quasirandom numbers and are they good for anything besides integration

What are quasirandom numbers and are they good for anything ...

2000 ANS International Topical Meeting on Advances in Reactor Physics and Mathematics and Computation into the Next Millennium, PHYSOR 2000

作者： Mascagni, Michael Karaivanova, Aneta Department of Computer Science Florida State University 203 Love Building TallahasseeFL32306-4530 United States Department of Computer Science Florida State University 203 Love Building TallahasseeFL32306-4530 United States Bulgarian Academy of Sciences Central Laboratory for Parallel Processing Sofia Bulgaria

ISBN: (纸本)0894486551

Monte Carlo methods are very general methods but suffer from the slow, O(N−1/2), convergence characteristic of random sampling. In recent years, the convergence of the Monte Carlo method for numerical integration has been improved by replacing pseudorandom numbers (PRNs) with more uniformly distributed numbers known as quasirandom numbers (QRNs). However, the advantages for numerical integration hold for integrals over the unit cube depend on many factors, such as the dimension and smoothness of the integrand, and whether or not the support of the integrand coincides with the unit cube. In the best cases, convergence for numerical integration becomes almost O(N−1), while in the worst cases convergence falls back to that obtained with PRNs. In this paper we will discuss the main motivation for QRNs, and give a brief overview of some methods of generating QRNs. Most importantly, we begin to consider whether Monte Carlo applications besides integration can be accelerated with QRNs. To this end we propose and study the applicability of QRNs for evaluating the largest and the smallest eigenvalue of a given matrix. This application makes use of QRNs in the evaluation of discrete Markov chains. In many areas of Monte Carlo transport, the evaluation of Markov chains is likewise undertaken. We believe that our success with this Markov chain example motivates further work in the application of QRNs to accelerate convergence of problems in transport Monte Carlo. The proposed quasi-Monte Carlo method based on Markov chain evaluation is a method for the computation of the extreme eigenvalues of a matrix. This method: • can be considered as modification of the Power Method but it avoids the LU-decomposition and the forward and backward solving of the factored system at every iteration step in the Inverse Power Method and Inverse Shifted Power Method. The resolvent matrix is presented as a series. This representation permits us to use the well-known random walk process on the elem

关键词： Monte Carlo methods

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Visual analyses of music download history: User studies 22nd

Visual analyses of music download history: User studies

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22nd International Conference on MultiMedia Modeling, MMM 2016

作者： Liu, Dong Zhang, Jingxian CAS Key Laboratory of Technology in Geo-spatial Information Processing and Application System University of Science and Technology of China Hefei China Department of Computer Science University of Illinois at Urbana-Champaign ChampaignIL United States

ISBN: (纸本)9783319276700

Users’ download history is a primary data source for analyzing user interests. Recent work has shown that user interests are indeed time varying, and accurate profiling of user interest drifts requires the temporal dynamic analyses. We have proposed a visualization approach to analyzing user interest drifts from the download history, taking music as an example, and studied how to depict the underlying relevances among the downloaded music items to identify the drifts. We designed three new kinds of plots to display the music download history of one user, namely Bean plot, Transitional Pie plot, and Instrument plot. In this paper, we report our conducted user studies that ask normal users to visually analyze the download history of other users in a given realworld data set. User studies are performed in a learning-practice-test workflow. The results demonstrate the feasibility of our visualization design. © Springer International Publishing Switzerland 2016.

关键词： Visualization

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Simultaneous segmentation and classification of colon cancer polyp images using a dual branch multi-task learning network

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Mathematical Biosciences and Engineering 2024年第2期21卷 2024-2049页

作者： Li, Chenqian Liu, Jun Tang, Jinshan School of Computer Science and Technology Wuhan University of Science and Technology Wuhan430065 China Hubei Province Key Laboratory of Intelligent Information Processing and Real-Time Industrial System Wuhan430065 China Department of Health Administration and Policy College of Public Health George Mason University FairfaxVA22030 United States

Accurate classification and segmentation of polyps are two important tasks in the diagnosis and treatment of colorectal cancers. Existing models perform segmentation and classification separately and do not fully make use of the correlation between the two tasks. Furthermore, polyps exhibit random regions and varying shapes and sizes, and they often share similar boundaries and backgrounds. However, existing models fail to consider these factors and thus are not robust because of their inherent limitations. To address these issues, we developed a multi-task network that performs both segmentation and classification simultaneously and can cope with the aforementioned factors effectively. Our proposed network possesses a dual-branch structure, comprising a transformer branch and a convolutional neural network (CNN) branch. This approach enhances local details within the global representation, improving both local feature awareness and global contextual understanding, thus contributing to the improved preservation of polyp-related information. Additionally, we have designed a feature interaction module (FIM) aimed at bridging the semantic gap between the two branches and facilitating the integration of diverse semantic information from both branches. This integration enables the full capture of global context information and local details related to polyps. To prevent the loss of edge detail information crucial for polyp identification, we have introduced a reverse attention boundary enhancement (RABE) module to gradually enhance edge structures and detailed information within polyp regions. Finally, we conducted extensive experiments on five publicly available datasets to evaluate the performance of our method in both polyp segmentation and classification tasks. The experimental results confirm that our proposed method outperforms other state-of-the-art methods. ©2024 the Author(s), licensee AIMS Press.

关键词： Classification (of information)

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Robust Semi-Global Leaderless Consensus and Containment Control of Identical Linear systems with Imperfect Actuators

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Journal of systems science & Complexity 2018年第1期31卷 69-86页

作者： SHI Liangren ZHAO Zhiyun LIN Zongli Department of Automation Shanghai Jiao Tong University and Key Laboratory of System Control and Information Processing of Ministry of Education Shanghai 200240 China Key Laboratory of Advanced Control and Optimization for Chemical Processes (East China University of Science and Technology) Ministry of Education Shanghai 200237 China Charles L. Brown Department of Electrical and Computer Engineering University of Virginia P.O. Box 400743 Charlottesville VA 22904-4743 USA

This paper investigates both the robust semi-global leaderless consensus problem and the robust semi-global containment control problem for a group of identical linear systems with imperfect actuators. The imperfect actuators are characterized by nonlinearities such as saturation and dead zone and there input output relationships are not precisely known. The dynamics of follower agents are also affected by the input additive disturbances. Low-and-high gain feedback consensus protocols are constructed to solve these problems. More specifically, it is shown that robust semi-global leaderless consensus can be achieved over a connected undirected graph and robust semi-global containment control can be achieved when each follower agent has access to the information of at least one leader agent. Numerical simulation illustrates the theoretical results.

关键词： Consensus containment control dead zone leaderless consensus multi-agent systems saturation

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Pharmaceutical semantic database query mechanism based on keywords

Pharmaceutical semantic database query mechanism based on ke...

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7th Chinese Semantic Web Symposium and the 2nd Chinese Web scienceConference, CSWS 2013

作者： Sun, Juan Gu, Jinguang Huang, Zhisheng Computer Science and Technology Wuhan University of Science and Technology Wuhan 430065 China Hubei Province Key Laboratory of Intelligent Information Processing and Realtime Industrial System Wuhan 430065 China Department of Computer Science Vrije University of Amsterdam 1081hv Amsterdam Netherlands

ISBN: (纸本)9783642540240

With the development of the Internet, Semantic search technology has been applied to various fields. In the pharmaceutical field, because of the huge number and wide range of the drugs on the market, an effective semantic retrieval system can bring great convenience for doctors. However, for doctors who have no background knowledge of semantic technologies, to write formal semantics search statement is still very difficult. Therefore, this paper proposes a pharmaceutical semantic database query mechanism which based on keywords. In this query mechanism, by analysis of ontology database and establishment of Chinese - English translation mapping, we can Transform Chinese keywords into English keywords. Then match the English keywords with ontology database to build a list of triples. And finally, formed Corresponding SPARQL query by analyze the list. © Springer-Verlag Berlin Heidelberg 2013.

关键词： Database systems

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Hierarchical categorization of open source software by online profiles

Hierarchical categorization of open source software by onlin...

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作者： Wang, Tao Wang, Huaimin Yin, Gang Yang, Cheng Li, Xiang Zou, Peng Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha 410073 China Department of Computer Science University of Western Ontario London ON N6A 5B7 Canada Academy of Equipment Beijing 100000 China

The large amounts of freely available open source software over the Internet are fundamentally changing the traditional paradigms of software development. Efficient categorization of the massive projects for retrieving relevant software is of vital importance for Internet-based software development such as solution searching, best practices learning and so on. Many previous works have been conducted on software categorization by mining source code or byte code, but were verified on only relatively small collections of projects with coarse-grained categories or clusters. However, Internet-based software development requires finer-grained, more scalable and language-independent categorization approaches. In this paper, we propose a novel approach to hierarchically categorize software projects based on their online profiles. We design a SVMbased categorization framework and adopt a weighted combination strategy to aggregate different types of profile attributes from multiple repositories. Different basic classification algorithms and feature selection techniques are employed and compared. Extensive experiments are carried out on more than 21,000 projects across five repositories. The results show that our approach achieves significant improvements by using weighted combination. Compared to the previous work, our approach presents competitive results with more finer-grained and multi-layered category hierarchy with more than 120 categories. Unlike approaches that use source code or byte code, our approach is more effective for large-scale and languageindependent software categorization. In addition, experiments suggest that hierarchical categorization combined with general keyword-based searching improves the retrieval efficiency and accuracy. Copyright © 2014 The Institute of Electronics, Information and Communication Engineers.

关键词： Open source software

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An effective control scheme to ensure real-time causal order in large-scale distributed interactive simulations

An effective control scheme to ensure real-time causal order...

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2011 IEEE 3rd International Conference on Communication Software and Networks, ICCSN 2011

作者： Zhou, Hangjun Fu, Sha Department of Information Management Hunan University of Finance and Economics Chang Sha Hu Nan China Key Laboratory of Science and Technology for National Defence of Parallel and Distributed Processing School of Computer Science National University of Defense Technology Chang Sha Hu Nan China

ISBN: (纸本)9781612844855

When a large-scale distributed interactive simulation system is running on WAN, the sites usually disperse over a wide area in geography, which results in the simulation clock of each site is hardly to be accurately synchronized with that of other sites. The asynchronous clocks and large transmission latency on WAN bring on a problem for the large-scale simulations to preserve the real-time causal order delivery of received events at each site. In this article, we analyze the indirect way to compare the values of asynchronous simulation clocks at first, and then propose a novel scheme which can select the reconstructible causal control information for each message so as to ensure the causal ordering of events in real time. Experiments demonstrate that the scheme can weaken the effect of network latency, reduce the overhead of the transmission amount of control information and improve the causal order consistency in asynchronous distributed simulations. © 2011 IEEE.

关键词： Real time control

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Two-Stage Robust Optimization Under Decision Dependent Uncertainty

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IEEE/CAA Journal of Automatica Sinica 2022年第7期9卷 1295-1306页

作者： Yunfan Zhang Feng Liu Yifan Su Yue Chen Zhaojian Wang João P.S.Catalão State Key Laboratory of Power System and Generation Equipment the Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Department of Mechanical and Automation Engineering the Chinese University of Hong KongHong Kong SARChina Ministry of Education Key Laboratory of System Control and Information Processing the Department of AutomationShanghai Jiao Tong Universityand also with Shanghai Engineering Research Center of Intelligent Control and ManagementShanghai 200240China Faculty of Engineering of the University of Porto and Institute for Systems and Computer Engineering Technology and Science(INESC TEC)Porto 4200-465Portugal IEEE

In the conventional robust optimization(RO)context,the uncertainty is regarded as residing in a predetermined and fixed uncertainty *** many applications,however,uncertainties are affected by decisions,making the current RO framework *** paper investigates a class of two-stage RO problems that involve decision-dependent *** introduce a class of polyhedral uncertainty sets whose right-hand-side vector has a dependency on the here-and-now decisions and seek to derive the exact optimal wait-and-see decisions for the second-stage problem.A novel iterative algorithm based on the Benders dual decomposition is proposed where advanced optimality cuts and feasibility cuts are designed to incorporate the uncertainty-decision *** computational tractability,robust feasibility and optimality,and convergence performance of the proposed algorithm are guaranteed with theoretical *** motivating application examples that feature the decision-dependent uncertainties are ***,the proposed solution methodology is verified by conducting case studies on the pre-disaster highway investment problem.

关键词： Benders decomposition decision-dependent uncertainty endogenous uncertainty robust optimization(RO)

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Bisimulations for open processes in higher order π-calculus

Bisimulations for open processes in higher order π-calculus

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2010 4th International Symposium on Theoretical Aspects of Software Engineering, TASE 2010

作者： Cao, Zining Department of Computer Science and Technology Nanjing University of Aero. and Astro. Nanjing 210016 China Provincial Key Laboratory for Computer Information Processing Technology Soochow University Suzhou 215006 China National Key Laboratory of Science and Technology on Avionics System Integration Shanghai 200233 China

ISBN: (纸本)9780769541488

In this paper, we propose open bisimulations for open processes in higher order π-calculus. The equivalence of open bisimulations and other bisimulations for open processes is proved. Furthermore, we present a symbolic operational semantics of higher order open processes, and give some symbolic bisimulations for higher order processes. The relation between symbolic bisimulations and other bisimulations is also studied. At last, we introduce a higher order π-calculus with sum and conditional operators, then we study open bisimulations and symbolic bisimulations for this calculus. © 2010 IEEE.

关键词： Calculations

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A causality based dynamic message ordering for DVEs on Wide Area Network

A causality based dynamic message ordering for DVEs on Wide ...

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IEEE International Conference on Communication Software and Networks

ISBN: (纸本)9781612844855

Due to the large message transmission latency in Distributed Virtual Environments(DVEs) on Wide Area Net-work(WAN), the effectiveness of causality consistency control of message ordering is determined by not only causal order of messages but also the real-timeness. If merely causal order is considered, the real-time property of DVEs may not be ensured because of the unlimited waiting time for the delayed messages. While if only real-timeness is emphasized, there may be too many delayed messages, which have to be discarded, to maintain the quality of causal message ordering. Therefore, a trade-off between the quality of causal order delivery and real-timeness is necessary for DVEs. In this article, a novel causality based message ordering approach is presented. In general, this new approach dynamically balances the demands of causal order delivery and real-timeness. Experiment results demonstrate the approach can enhance the quality of causality, while simultaneously keep the real-time property of DVEs. © 2011 IEEE.

关键词： Wide area networks

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