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Science China(Physics,Mechanics & Astronomy) 2003年第2期46卷 145-157页

作者：徐明瑜谭文长 Institute of Mathematics and Systematical Science Research Center for Biomedical EngineeringShandong UniversityJinan 250100China Department of Mechanical Engineering Science Faculty of EngineeringKyushu UniversityFukuoka 812-8581JapanDepartment of Mechanics and Engineering SciencePeking UniversityBeijing 100871China

The generalized fractional element networks are presented in this paper. In order to extend the structure of the model solutions to the generalized function space and make it contain more physical meanings, the restriction on the parameters of the fractional element proposed by Schiessel et al. is eliminated and a 'compatibility equation' is added. The discretization method for solving the inverse Laplace transform is used and developed. The generalized solutions of the model equations are given. At the same time the generalized fractional element network--Zener and Poyinting-Thomson models are discussed in detail. It is shown that all the results obtained previously about the models of single parameter with fractional order and the classical models with integer order can be contained as the special cases of the results of this paper.

关键词： viscoelastic material, constitutive equation, generalized fractional element networks, fractional calculus, generalized solution.

Dynamic multimedia stream adaptation and rate control for heterogeneous networks

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第Z1期7卷 63-69页

作者： SZWABE Andrzej SCHORR Andreas HAUCK Franz J. KASSLER Andreas J. Poznan University of Technology Poznan 60-965 Poland University of Ulm Ulm 89069 Germany University of Karlstad Karlstad SE-65188 Sweden

Dynamic adaptation of multimedia content is seen as an important feature of next generation networks and pervasive systems enabling terminals and applications to adapt to changes in e.g. context, access network, and available Quality-of-Service(QoS) due to mobility of users, devices or sessions. We present the architecture of a multimedia stream adaptation service which enables communication between terminals having heterogeneous hardware and software capabilities and served by heterogeneous networks. The service runs on special content adaptation nodes which can be placed at any location within the network. The flexible structure of our architecture allows using a variety of different adaptation engines. A generic transcoding engine is used to change the codec of streams. An MPEG-21 Digital Item Adaptation (DIA) based transformation engine allows adjusting the data rate of scalable media streams. An intelligent decision-taking engine implements adaptive flow control which takes into account current network QoS parameters and congestion information. Measurements demonstrate the quality gains achieved through adaptive congestion control mechanisms under conditions typical for a heterogeneous network.

关键词： Stream adaptation, Quality-of-Service (QoS), Heterogeneous networks, Rate control, MPEG-21 DIA

Joint routing and rate allocation for multiple video streams in ad-hoc wireless networks

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第5期7卷 727-736页

作者： SINGH Jatinder Pal GIROD Bernd Deutsche Telekom Laboratories Ernst-Reuter-Platz 7 Berlin 10587 Germany Information System Laboratory Stanford University California 94305 USA

The support for multiple video streams in an ad-hoc wireless network requires appropriate routing and rate allocation measures ascertaining the set of links for transmitting each stream and the encoding rate of the video to be delivered over the chosen links. The routing and rate allocation procedures impact the sustained quality of each video stream measured as the mean squared error (MSE) distortion at the receiver, and the overall network congestion in terms of queuing delay per link. We study the trade-off between these two competing objectives in a convex optimization formulation, and discuss both centralized and dis- tributed solutions for joint routing and rate allocation for multiple streams. For each stream, the optimal allocated rate strikes a balance between the selfish motive of minimizing video distortion and the global good of minimizing network congestions, while the routes are chosen over the least-congested links in the network. In addition to detailed analysis, network simulation results using ns-2 are presented for studying the optimal choice of parameters and to confirm the effectiveness of the proposed measures.

关键词： Ad-hoc wireless networks, Video streaming, Rate allocation, Multi-path routing

Experimental evaluation of an on-demand multipath routing protocol for video transmission in mobile ad hoc networks

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第Z1期7卷 145-150页

作者： TANIYAMA Kenta MORII Takeshi KOIZUMI Shinya NOGUCHI Kazuhiro KOTANI Yukihiro KATTO Jiro Graduate School of Science and Engineering Waseda University Tokyo 169-8555Japan

We propose an on-demand multipath routing algorithm in a mobile ad hoc network for video transmission and evaluate its real world performance in video streaming application. There have been a number of multipath routing protocols extended from AODV which is a well-known single path routing protocol. Multipath routing protocols indicate good performance in the reduction of route discovery latency and unnecessary routing packets in simulations. We show that the route establishment using source route lists provided by us (Hu and Johnson, 2002) can reduce the route discovery latency, select stable routes automatically, and work well for live video streaming without limitation of the hop count based approaches. We evaluate this proposed method compared with the original AODV by using eight laptop PCs and demonstrate live streaming experiments.

关键词： Mobile ad hoc networks, AODV, Multipath routing, Source routes

Fabrication and characterization of multidimensional tungsten oxide networks

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Science China Chemistry 2005年第6期48卷 511-515页

作者： WEI Xiaolan SHEN Peikang Department of Applied Chemistry South China University of Technology Guangzhou 510641 China State Key Laboratory of Optoelectromic Materials and Technologies School of Physics and Engineering Sun Yat-Sen University Guangzhou 510275 China

Multidimensional WO3 networks with hierarchical bimodal pores have been syn-chronously fabricated by concentrating a solution containing hydrogen peroxide, methanol, per-oxo-polytungstic acid and poly (n-vinylpyrrolidone) (PVP). The optical microscope, SEM, powder XRD, TG, HRTEM, and N2 adsorption (BET) techniques have been used to characterize the as-prepared and calcined WO3 networks. The optical photographs of the as-prepared WO3 and the SEM images of calcined WO3 show that they possess multidimensional networks. WO3 foams with multidimensional networks are stable no matter heat-treated or not, showing a self-supporting characteristic. The enlarged SEM image of the calcined WO3 networks proves that the walls of the networks are assembled by WO3 nanoparticles. The XRD spectra of the WO3 exhibit that the as-prepared sample is amorphous and the calcined one is the orthorhombic structure. The N2 adsorption analysis shows a type IV isotherm for calcined WO3 networks. The hysteresis of N2 desorption at p/p0 > 0.6 clearly indicates the presence of mesopores and the sharp increase in the volume adsorbed near p/p0 = 1 shows the existence of macropores. The mesopores in the walls of calcined WO3 networks are observed in the HRTEM image. PVP used as a structure-directing agent is cheap and can stabilize the preparation solution.

关键词： multidimensional networks, tungsten oxide, foam, nanoparticles, macropore.

A novel model-free approach for reconstruction of time-delayed gene regulatory networks

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中国科学：生命科学英文版 2006年第2期49卷 190-200页

作者： JIANG Wei1,2, LI Xia1,2,3,4, GUO Zheng1,2,3, LI Chuanxing1, WANG Lihong1 & RAO Shaoqi1,5 1. Department of Bioinformatics, Harbin Medical University, Harbin 150086, China 2. Department of Computer Science, Harbin Institute of Technology, Harbin 150080, China 3. School of Life Science and Technology, Tongji University, Shanghai 200092, China 4. Biomedical Engineering Institute, Capital University of Medical Sciences, Beijing 100054, China 5. Departments of Cardiovascular Medicine and Molecular Cardiology, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA Department of Bioinformatics Harbin Medical University Harbin China Department of Computer Science Harbin Institute of Technology Harbin China School of Life Science and Technology Tongji University Shanghai China Departments of Cardiovascular Medicine and Molecular Cardiology Cleveland Clinic Foundation Cleveland USA

Reconstruction of genetic networks is one of the key scientific challenges in functional genomics. This paper describes a novel approach for addressing the regulatory dependencies be-tween genes whose activities can be delayed by multiple units of time. The aim of the proposed ap-proach termed TdGRN (time-delayed gene regulatory networking) is to reversely engineer the dy-namic mechanisms of gene regulations, which is realized by identifying the time-delayed gene regu-lations through supervised decision-tree analysis of the newly designed time-delayed gene expres-sion matrix, derived from the original time-series microarray data. A permutation technique is used to determine the statistical classification threshold of a tree, from which a gene regulatory rule(s) is ex-tracted. The proposed TdGRN is a model-free approach that attempts to learn the underlying regula-tory rules without relying on any model assumptions. Compared with model-based approaches, it has several significant advantages: it requires neither any arbitrary threshold for discretization of gene transcriptional values nor the definition of the number of regulators (k). We have applied this novel method to the publicly available data for budding yeast cell cycling. The numerical results demonstrate that most of the identified time-delayed gene regulations have current biological knowledge supports.

关键词： gene regulatory networks, time delayed, decision tree.

An infinite family of 4-tight optimal double loop networks

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Science China Mathematics 2003年第1期46卷 139-143页

作者：徐俊明刘琦 Department of Mathematics University of Science and Technology of China

An infinite family of 4-tight optimal double loop networks is given in this paper.

关键词： networks, double loop networks, circulant digraphs, optimal, tight optimal.

Distributed media cooperation for enhanced video communication

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第5期7卷 773-783页

作者： CHAKARESKI Jacob Ecole Polytechnique Fédérale de Lausanne

The author designed two algorithms for distributed cooperation among multiple video streams sharing common communication resources. The algorithms take advantage of an optimization framework that characterizes video packets such that joint resource allocation can be implemented not only over the packets of a single stream, but also across packets of different streams. The first algorithm enables collaboration among multiple video senders in an 802.11 CSMA/CA wireless network such that their joint performance is maximized. Via the algorithm, the users cooperatively establish transmission priorities based on the assigned characterizations of their video packets. The second technique allows for low-complexity joint bandwidth adaptation of multiple video streams at intermediate network nodes in the Internet in order to maximize the overall network performance. The author analyzes the advantages of the proposed algorithms over conventional solutions employed in such scenarios. It is shown that depending on system parameters such as available network data rate the proposed techniques can provide substantial gains in end-to-end performance.

关键词： Media cooperation, Distributed video streaming, Wireless networks, Resource allocation, Rate-quality optimization

Existence problem of optical correlation based pattern recognition

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Science China(Physics,Mechanics & Astronomy) 2003年第6期46卷 589-601页

作者： ZHANG Yanxin(张延炘) LI Sumei(李素梅) Institute of Modern Optics Nankai University Tianjin 300071 China Optoelectronic Information Technical Science Laboratory Ministry of Education China Institute of Modern Optics Nankai University Tianjin 300071 China Optoelectronic Information Technical Science Laboratory Ministry of Education China

The existence problem of optical correlation based pattern recognition, namely its range of validity and its limitation, is discussed in this paper conjointly with the function approximation theory of neural networks. The conclusion is that only if the sets to be recognized are linearly separable (which is rare) or the subsets, in which a segmental sample of the targets is involved,are linearly separable, can the classical 4f optical correlation system carry out the task of recognition inerrably. The recognition principle of a joint transform correlator is the same as that of a 4f system, and so is its range of validities. Based on the demonstration of the existence problem of optical correlation based pattern recognition an evaluation on some important problems that were studied in this field over the past 40 years is presented explicitly.

关键词： optical correlation, automatic target recognition, artificial neural networks, existence theorem.

BulkTree: an overlay network architecture for live media streaming

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第Z1期7卷 125-130页

作者： GONG An DING Gui-guang DAI Qiong-hai LIN Chuang Department of Computer Science & Technology Tsinghua University Beijing 100084 China Broadband Networks & Digital Media Laboratory Department of Automation Tsinghua University Beijing 100084 China Broadband Networks & Digital Media Laboratory Department of Automation Tsinghua University Beijing 100084 China Department of Computer Science & Technology Tsinghua University Beijing 100084 China

Peer-to-peer (P2P) systems are now very popular. Current P2P systems are broadly of two kinds, structured and unstructured. The tree structured P2P systems used technologies such as distributed hash tables (DHT) and hierarchical clustering can search the required target quickly, however, in a tree, the internal node has a higher load and its leave or crash often causes a large population of its offspring's problems, so that in the highly dynamic Internet environment the tree structure may still suffer frequent breaks. On the other hand, most widely used unstructured P2P networks rely on central directory servers or massive message flooding, clearly not scalable. So, we consider both of the above systems' advantages and disadvantages and realize that in the P2P systems one node may fail easily, but that when a number of nodes organized as a set, which we call "super node", the set is robust. Super nodes can be created and updated aware of topology-aware, and used with simple protocol such as flooding or "servers" to exchange information. Furthermore the entire robust super node can be organized into exquisite tree structure. By using this overlay network architecture, P2P systems are robust, efficient, scalable and secure. The simulation results demonstrated that our architecture greatly reduces the alteration time of the structure while decreasing the average delay time, compared to the common tree structure.

关键词： Peer-to-peer (P2P), Overlay networks, Scalability, Live media, Distributed hash tables (DHT), Hierarchical clustering