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Iterative Learning Control With Incomplete Information： A Survey

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IEEE/CAA Journal of Automatica Sinica 2018年第5期5卷 885-901页

作者： Dong Shen Senior member IEEE ieee beijing university of chemical technology

Abstract--This paper conducts a survey on iterative learn- ing control （ILC） with incomplete information and associated control system design, which is a frontier of the ILC field. The incomplete information, including passive and active types, can cause data loss or fragment due to various factors. Passive incomplete information refers to incomplete data and information caused by practical system limitations during data collection, storage, transmission, and processing, such as data dropouts, delays, disordering, and limited transmission bandwidth. Active incomplete information refers to incomplete data and information caused by man-made reduction of data quantity and quality on the premise that the given objective is satisfied, such as sampling and quantization. This survey emphasizes two aspects： the first one is how to guarantee good learning performance and tracking performance with passive incomplete data, and the second is how to balance the control performance index and data demand by active means. The promising research directions along this topic are also addressed, where data robustness is highly emphasized. This survey is expected to improve understanding of the restrictive relationship and trade-off between incomplete data and tracking performance, quantitatively, and promote further developments of ILC theory. Index Terms--Data dropout, data robustness, incomplete in- formation, iterative learning controi（ILC）, quantized control, sampled control, varying lengths.

关键词： Data dropout data robustness incomplete information iterative learning control(ILC) quantized control sampled control varying lengths

Control Strategy Optimization of Voltage Source Converter Connected to Various Types of AC Systems

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Journal of Modern Power Systems and Clean Energy 2021年第1期9卷 77-84页

作者： Zehong Liu Senior member Xianshan Guo State Grid Corporation of China Beijing 100031China

Connecting the voltage source converters(VSCs) to various types of AC systems results in different operation characteristics and core problems associated with traditional control strategies. Therefore, it is necessary to optimize the control strategies of the VSCs according to the types of AC *** the VSCs connected to islanded renewable power plants, a voltage/frequency(V/f) droop control strategy is proposed to damp fluctuations of AC voltage and frequency in the island,which is vital for bipolar VSC control. In addition, a multibranch impedance equivalent method for renewable power plants is proposed, with which large-scale renewable power plants can be modeled accurately in the frequency domain to prevent wide-band oscillation. For the VSCs connected to strong AC systems, smart AC voltage and coordinated frequency transient control strategies are proposed, which can improve AC system transient stability. For the VSCs connected to weak AC systems, the relationship between the system stability and strength is analyzed, and then the control strategy of inner-loop control parameter optimization and outer-loop power limiting(if necessary) is proposed to improve the stability of the allied system. The proposed strategies are verified by both software simulation and field commissioning.

关键词： Control strategy optimization islanded renewable power plants stability voltage source converter(VSC) AC system

Interactive Fault Localization Using Test Information

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Journal of Computer Science & Technology 2009年第5期24卷 962-974页

作者：郝丹张路 Senior member 谢涛梅宏孙家骕 Key Laboratory of High Confidence Software Technologies Ministry of Education Institute of Software School of Electronics Engineering and Computer Science Peking University Beijing 100871 China Department of Computer Science North Carolina State University Raleigh NC 27695 U.S.A.

Debugging is a time-consuming task in software development. Although various automated approaches have been proposed, they are not effective enough. On the other hand, in manual debugging, developers have difficulty in choosing breakpoints. To address these problems and help developers locate faults effectively, we propose an interactive fault-localization framework, combining the benefits of automated approaches and manual debugging. Before the fault is found, this framework continuously recommends checking points based on statements＇ suspicions, which are calculated according to the execution information of test cases and the feedback information from the developer at earlier checking points. Then we propose a naive approach, which is an initial implementation of this framework. However, with this naive approach or manual debugging, developers＇ wrong estimation of whether the faulty statement is executed before the checking point （breakpoint） may make the debugging process fail. So we propose another robust approach based on this framework, handling cases where developers make mistakes during the fault-localization process. We performed two experimental studies and the results show that the two interactive approaches are quite effective compared with existing fault-localization approaches. Moreover, the robust approach can help developers find faults when they make wrong estimation at some checking points.

关键词： debugging fault localization interactive approach

Level-of-Detail Rendering of Large-Scale Irregular Volume Datasets Using Particles

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Journal of Computer Science & Technology 2010年第5期25卷 905-915页

作者： Takuma Kawamura Naohisa Sakamoto Koji Koyamada member, IEEE Graduate School of Engineering Kyoto University Kyoto 6068501 Japan Center for the Promotion of Excellence in Higher Education Kyoto University Kyoto 6068501 Japan

This paper describes a level-of-detail rendering technique for large-scale irregular volume *** is well known that the memory bandwidth consumed by visibility sorting becomes the limiting factor when carrying out volume rendering of such *** develop a sorting-free volume rendering technique,we previously proposed a particle-based technique that generates opaque and emissive particles using a density function constant within an irregular volume cell and projects the particles onto an image plane with *** the density function changes significantly in an irregular volume cell,the cell boundary may become prominent,which can cause blocky *** the number of the sub-pixels increases,the required frame buffer tends to be *** solve this problem,this work proposes a new particle-based volume rendering which generates particles using metropolis sampling and renders the particles using the ensemble average. To confirm the effectiveness of this method,we applied our proposed technique to several irregular volume datasets,with the result that the ensemble average outperforms the sub-pixel average in computational complexity and memory usage. In addition,the ensemble average technique allowed us to implement a level of detail in the interactive rendering of a 71-million-cell hexahedral volume dataset and a 26-million-cell quadratic tetrahedral volume dataset.

关键词： large-scale irregular volume level-of-detail volume rendering of unstructured meshes

Harnessing the Power of GPUs to Speed Up Feature Selection for Outlier Detection

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Journal of Computer Science & Technology 2014年第3期29卷 408-422页

作者： Fatemeh Azmandian member, IEEE, Ayse Yilmazer Student member, IEEE, Jennifer G. Dy member, IEEE Javed A. Aslam IEEE, Jennifer G. Dy member, ACM David R. Kaeli Fellow, IEEE, member, ACM Department of Electrical and Computer Engineering Northeastern University Boston 02115-5096 U.S.A. College of Computer and Information Science Northeastern University Boston 02115-5096 U.S.A.

Acquiring a set of features that emphasize the differences between normal data points and outliers can drastically facilitate the task of identifying outliers. In our work, we present a novel non-parametric evaluation criterion for filter-based feature selection which has an eye towards the final goal of outlier detection. The proposed method seeks the subset of features that represent the inherent characteristics of the normal dataset while forcing outliers to stand out, making them more easily distinguished by outlier detection algorithms. Experimental results on real datasets show the advantage of our feature selection algorithm compared with popular and state-of-the-art methods. We also show that the proposed algorithm is able to overcome the small sample space problem and perform well on highly imbalanced datasets. Furthermore, due to the highly parallelizable nature of the feature selection, we implement the algorithm on a graphics processing unit （GPU） to gain significant speedup over the serial version. The benefits of the GPU implementation are two-fold, as its performance scales very well in terms of the number of features, as well as the number of data points.

关键词： feature selection outlier detection imbalanced data GPU acceleration

A Review-Based Reputation Evaluation Approach for Web Services

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Journal of Computer Science & Technology 2009年第5期24卷 893-900页

作者：李海华杜小勇 member 田萱 Key Laboratory of Data Engineering and Knowledge Engineering (Renmin University of China) MOE Beijing 100872 China School of Information Renmin University of China Beijing 100872 China School of Information Science & Technology Beijing Forestry University Beijing 100083 China

Web services are commonly perceived as an environment of both offering opportunities and threats. In this environment, one way to minimize threats is to use reputation evaluation, which can be computed, for example, through transaction feedback. However, the current feedback-based approach is inaccurate and ineffective because of its inner limitations （e.g., feedback quality problem）. As the main source of feedback, the qualities of existing on-line reviews are often varied greatly from low to high, the main reasons include：（1） they have no standard expression formats, （2） dishonest comments may exist among these reviews due to malicious attacking. Up to present, the quality problem of review has not been well solved, which greatly degrades their importance on service reputation evaluation. Therefore, we firstly present a novel evaluation approach for review quality in terms of multiple metrics. Then, we make a further improvement in service reputation evaluation based on those filtered reviews. Experimental results show the effectiveness and efficiency of our proposed approach compared with the naive feedback-based approaches.

关键词： Web services reputation evaluation review quality measurement

A Multi-Key Pirate Decoder Against Traitor Tracing Schemes

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Journal of Computer Science & Technology 2010年第2期25卷 362-374页

作者：吴永东 member, IEEE 邓慧杰 Institute for Infocomm Research A STAR 138632 Singapore School of Information Systems Singapore Management University 178902 Singapore

In this paper we introduce an architecture for a multi-key pirate decoder which employs decryption keys from multiple traitors. The decoder has built-in monitoring and self protection functionalities and is capable of defeating most multiple-round based traitor tracing schemes such as the schemes based on the black-box confirmation method. In particular, the proposed pirate decoder is customized to defeat the private key and the public key fully collusion resistant traitor tracing （FTT） schemes, respectively. We show how the decoder prolongs a trace process so that the tracer has to give up his effort. FTT schemes are designed to identify all the traitors. We show that decoder enables the FTT schemes to identify at most 1 traitors. Finally, assuming the decoder is embedded with several bytes of memory, we demonstrate how the decoder is able to frame innocent users at will.

关键词： broadcast encryption multi-key pirate decoder traitor tracing

DICE:An Effective Query Result Cache for Distributed Storage Systems

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Journal of Computer Science & Technology 2010年第5期25卷 933-944页

作者： Jun-Ki Min member, A CM Mi-Young Lee School of Computer Science and Engineering Korea University of Technology and Education Byeongcheon-myeon Cheonan Chungnam 330-708 Korea Cloud Computing Research Department Electronics and Telecommunications Research Institute (ETRI) Daejeon 305-700 Korea

Due to the proliferation of Internet and Intranet,the distributed storage systems have received a lot of attention. These systems span a large number of machines and store huge amount of data for a lot of *** the distributed storage systems,a row can be directly accessed using a row *** concentrate on a problem of efficient processing of queries whose predicate is on a column but not a row *** this paper,we present a cache management technique,called DICE which maintains query results of range queries to support the next range *** accelerate the search time of the cached query results,we use modified Interval Ski *** addition,we devise a novel cache replacement policy since DICE maintains an interval rather than a data *** our cache replacement policy considers the properties of intervals,our proposed technique is more efficient than traditional buffer replacement *** experimental result demonstrates the efficiency of our proposed technique.

关键词： distributed system range query query caching Interval Skip List cache replacement

Tree-Based Index Overlay in Hybrid Peer-to-Peer Systems

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Journal of Computer Science & Technology 2010年第2期25卷 313-329页

作者： InSung Kang SungJin Choi member, IEEE SoonYoung Jung SangKeun Lee Computer Science and Engineering Department Korea University Seoul 136-713 Korea Corporate Center KT (Korea Telecom) Seoul 137-792 Korea Computer Science Education Department Korea University Seoul 136-701 Korea

Hybrid Peer-to-Peer （P2P） systems that construct overlay networks structured among superpeers have great potential in that they can give the benefits such as scalability, search speed and network traffic, taking advantages of superpeer-based and the structured P2P systems. In this article, we enhance keyword search in hybrid P2P systems by constructing a tree-based index overlay among directory nodes that maintain indices, according to the load and popularity of a keyword. The mathematical analysis shows that the keyword search based on semi-structured P2P overlay can improve the search performance, reducing the message traffic and maintenance costs.

关键词： tree-based index overlay keyword search fault-tolerance performance