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Assisting Visually Impaired People to Acquire Targets on a Large Wall-Mounted Display

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Journal of Computer Science & Technology 2014年第5期29卷 825-836页

作者： Kibum Kim member Acm IEEE 任向实 Senior member Center for Human Computer Interaction Kochi University of Technology Kochi 782-8502 Japan

Large displays have become ubiquitous in our everyday lives, but these displays are designed for sighted *** paper addresses the need for visually impaired people to access targets on large wall-mounted displays. We developed an assistive interface which exploits mid-air gesture input and haptic feedback, and examined its potential for pointing and steering tasks in human computer interaction（HCI）. In two experiments, blind and blindfolded users performed target acquisition tasks using mid-air gestures and two different kinds of feedback（i.e., haptic feedback and audio feedback）. Our results show that participants perform faster in Fitts＇ law pointing tasks using the haptic feedback interface rather than the audio feedback interface. Furthermore, a regression analysis between movement time（MT） and the index of difficulty（ID）demonstrates that the Fitts＇ law model and the steering law model are both effective for the evaluation of assistive interfaces for the blind. Our work and findings will serve as an initial step to assist visually impaired people to easily access required information on large public displays using haptic interfaces.

关键词： haptic I/O auditory(non-speech) feedback interaction style human computer interaction visually impaired people

Parallel LDPC Decoding on GPUs Using a Stream-Based Computing Approach

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Journal of Computer Science & Technology 2009年第5期24卷 913-924页

作者： Gabriel Falcao Student member Shinichi Yamagiwa Vitor Silva Leonel Sousa Senior member Department of Electrical and Computer Engineering University of Coimbra Instituto de Telecomunicacoes PoloⅡUniversidade de Coimbra 3030-290 Coimbra Portugal INESC-ID Technical University of Lisbon Rua Alves Redol n.9 1000-029 Lisboa Portugal Department of Electrical and Computer Engineering IST Technical University of Lisbon Rua Alves Redol n.9 1000-029 Lisboa Portugal

Low-Density Parity-Check （LDPC） codes are powerful error correcting codes adopted by recent communication standards. LDPC decoders are based on belief propagation algorithms, which make use of a Tanner graph and very intensive message-passing computation, and usually require hardware-based dedicated solutions. With the exponential increase of the computational power of commodity graphics processing units （GPUs）, new opportunities have arisen to develop general purpose processing on GPUs. This paper proposes the use of GPUs for implementing flexible and programmable LDPC decoders. A new stream-based approach is proposed, based on compact data structures to represent the Tanner graph. It is shown that such a challenging application for stream-based computing, because of irregular memory access patterns, memory bandwidth and recursive flow control constraints, can be efficiently implemented on GPUs. The proposal was experimentally evaluated by programming LDPC decoders on GPUs using the Caravela platform, a generic interface tool for managing the kernels＇ execution regardless of the GPU manufacturer and operating system. Moreover, to relatively assess the obtained results, we have also implemented LDPC decoders on general purpose processors with Streaming Single Instruction Multiple Data （SIMD） Extensions. Experimental results show that the solution proposed here efficiently decodes several codewords simultaneously, reducing the processing time by one order of magnitude.

关键词： data-parallel computing graphics processing unit (GPU) Caravela low-density parity-check (LDPC) code error correcting code

ROAD+:Route Optimization with Additional Destination-Information and Its Mobility Management in Mobile Networks

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Journal of Computer Science & Technology 2010年第2期25卷 298-312页

作者： Moonseong Kim Matt W. Mutka member, Acm Senior member Jeonghoon Park Hyunseung Choo Department of Computer Science and Engineering Michigan State University East Lansing MI 48824 U.S.A. Digital Media and Communication Business Samsung Electronics Korea School of Information and Communication Engineering Sungkyunkwan University 440-746 Korea

In the NEtwork MObility （NEMO） environment, mobile networks can form a nested structure. In nested mobile networks that use the NEMO Basic Support （NBS） protocol, pinball routing problems occur because packets are routed to all the home agents of the mobile routers using nested tunneling. In addition, the nodes in the same mobile networks can communicate with each other regardless of Internet connectivity. However, the nodes in some mobile networks that are based on NBS cannot communicate when the network is disconnected from the Internet. In this paper, we propose a route optimization scheme to solve these problems. We introduce a new IPv6 routing header named ＂destination-information header＂（DH）, which uses DH instead of routing header type 2 to optimize the route in the nested mobile network. The proposed scheme shows at least 30% better performance than ROTIO and similar performance improvement as DBU in inter-route optimization. With respect to intra-route optimization, the proposed scheme always uses the optimal routing path. In addition, the handover mechanism in ROAD＋ outperforms existing schemes and is less sensitive to network size than other existing schemes.

关键词： NEtwork MObility (NEMO) route optimization (RO) NEMO basic support (NBS) pinball routing problem mobile network nested mobile network

Global-to-Local Approach to Rigorously Developing Distributed System with Exception Handling

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Journal of Computer Science & Technology 2009年第2期24卷 238-249页

作者：蔡超裘宗燕 Senior member, member, CCF, IEEE 杨红丽赵翔鹏 LMAM and Department of Informatics School of Mathematical Science Peking University Beijing 100871 China College of Computer Sciences Beijing University of Technology Beijing 100124 China

Cooperative distributed system covers a wide range of applications such as the systems for industrial controlling and business-to-business trading, which are usually safety-critical. Coordinated exception handling （CEH） refers to exception handling in the cooperative distributed systems, where exceptions raised on a peer should be dealt with by all relevant peers in a consistent manner. Some CEH algorithms have been proposed. A crucial problem in using these algorithms is how to develop the peers which are guaranteed coherent in both normal execution and exceptional execution. Straightforward testing or model checking is very expensive. In this paper, we propose an effective way to rigorously develop the systems with correct CEH behavior. Firstly, we formalize the CEH algorithm by proposing a Peer Process Language to precisely describe the distributed systems and their operational semantics. Then we dig out a set of syntactic conditions, and prove its sufficiency for system coherence. Finally~ we propose a global-to-local approach, including a language describing the distributed systems from a global perspective and a projection algorithm, for developing the systems. Given a well-formed global description, a set of peers can be generated automatically. We prove the system composed of these peers satisfies the conditions, that is, it is always coherent and correct for CEH.

关键词： distributed system exception handling fault tolerant formal methods

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