Please wait a minute...

Current Issue

, Volume 6 Issue 6   
A tunable dual-broad-band branch-line coupler utilizing composite right/left-handed transmission lines
ZHANG Yu, HU Li, HE Sai-ling
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 1-.   https://doi.org/10.1631/jzus.2005.A0483
Abstract   PDF (0KB)
A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two |?/4 segments consisting of CRLH transmission lines are added to each port to broaden the dual bands of the branch-line coupler. Numerical simulation and optimal design of the novel coupler are presented. The dual bands of the novel coupler are tunable and broad. The 1-dB bandwidth of each pass band is more than 16% of the central frequency.
Super-resolution inpainting
SHIH Timothy K., CHANG Rong-chi
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 2-.   https://doi.org/10.1631/jzus.2005.A0487
Abstract   PDF (0KB)
Image or video resources are often received in poor condition, mostly with noise or defects making the resources hard to read. We propose an effective algorithm based on digital image inpainting. The mechanism can be used in restoring images or video frames with very high noise or defect ratio (e.g., 90%). The algorithm is based on the concept of image subdivision and estimation of color variations. Noises inside blocks of different sizes are inpainted with different levels of surrounding information. The results showed that an almost unrecognizable image can be recovered with visually good result. The algorithm can be further extended for processing motion picture with high percentage of noise.
A two-step rectification algorithm for airborne linear images with POS data
TUO Hong-ya, LIU Yun-cai
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 3-.   https://doi.org/10.1631/jzus.2005.A0492
Abstract   PDF (0KB)
Rectification for airborne linear images is an indispensable preprocessing step. This paper presents in detail a two-step rectification algorithm. The first step is to establish the model of direct georeference position using the data provided by the Positioning and Orientation System (POS) and obtain the mathematical relationships between the image points and ground reference points. The second step is to apply polynomial distortion model and Bilinear Interpolation to get the final precise rectified images. In this step, a reference image is required and some ground control points (GCPs) are selected. Experiments showed that the final rectified images are satisfactory, and that our two-step rectification algorithm is very effective.
B¨|zier curves with shape parameter
WANG Wen-tao, WANG Guo-zhao
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 4-.   https://doi.org/10.1631/jzus.2005.A0497
Abstract   PDF (0KB)
In this paper, B¨|zier basis with shape parameter is constructed by an integral approach. Based on this basis, we define the B¨|zier curves with shape parameter. The B¨|zier basis curves with shape parameter have most properties of Bernstein basis and the B¨|zier curves. Moreover the shape parameter can adjust the curves?ˉ shape with the same control polygon. As the increase of the shape parameter, the B¨|zier curves with shape parameter approximate to the control polygon. In the last, the B¨|zier surface with shape parameter is also constructed and it has most properties of B¨|zier surface.
A fast direct point-by-point generating algorithm for B Spline curves and surfaces
LI Zhong, HAN Dan-fu
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 5-.   https://doi.org/10.1631/jzus.2005.A0502
Abstract   PDF (0KB)
Traditional generating algorithms for B Spline curves and surfaces require approximation methods where how to increment the parameter to get the best approximation is problematic; or they take the pixel-based method needing matrix transformation from B Spline representation to B¨|zier form. Here, a fast, direct point-by-point generating algorithm for B Spline curves and surfaces is presented. The algorithm does not need matrix transformation, can be used for uniform or nonuniform B Spline curves and surfaces of any degree, and has high generating speed and good rendering accuracy.
Research on fast real-time adaptive audio mixing in multimedia conference
FAN Xing, GU Wei-kang, YE Xiu-qing
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 6-.   https://doi.org/10.1631/jzus.2005.A0507
Abstract   PDF (0KB)
In multimedia conference, the capability of audio processing is basic and requires more for real-time criteria. In this article, we categorize and analyze the schemes, and provide several multipoint speech audio mixing schemes using weighted algorithm, which meet the demand of practical needs for real-time multipoint speech mixing, for which the ASW and AEW schemes are especially recommended. Applying the adaptive algorithms, the high-performance schemes we provide do not use the saturation operation widely used in multimedia processing. Therefore, no additional noise will be added to the output. The above adaptive algorithms have relatively low computational complexity and good hearing perceptibility. The schemes are designed for parallel processing, and can be easily implemented with hardware, such as DSPs, and widely applied in multimedia conference systems.
A distributed software architecture design framework based on attributed grammar
JIA Xiao-lin, QIN Zheng, HE Jian, YU Fan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 7-.   https://doi.org/10.1631/jzus.2005.A0513
Abstract   PDF (0KB)
Software architectures shift the focus of developers from lines-of-code to coarser-grained architectural elements and their overall interconnection structure. There are, however, many features of the distributed software that make the developing
Construction and compression of Dwarf
XIANG Long-gang, FENG Yu-cai, GUI Hao
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 8-.   https://doi.org/10.1631/jzus.2005.A0519
Abstract   PDF (0KB)
There exists an inherent difficulty in the original algorithm for the construction of Dwarf, which prevents it from constructing true Dwarfs. We explained when and why it introduces suffix redundancies into the Dwarf structure. To solve this pro
Optimal choice of parameters for particle swarm optimization
ZHANG Li-ping, YU Huan-jun, HU Shang-xu
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 9-.   https://doi.org/10.1631/jzus.2005.A0528
Abstract   PDF (0KB)
The constriction factor method (CFM) is a new variation of the basic particle swarm optimization (PSO), which has relatively better convergent nature. The effects of the major parameters on CFM were systematically investigated based on some benchmark functions. The constriction factor, velocity constraint, and population size all have significant impact on the performance of CFM for PSO. The constriction factor and velocity constraint have optimal values in practical application, and improper choice of these factors will lead to bad results. Increasing population size can improve the solution quality, although the computing time will be longer. The characteristics of CFM parameters are described and guidelines for determining parameter values are given in this paper.
Optimal bandwidth scheduling of networked control systems (NCSs) in accordance with jitter
BAI Tao, WU Zhi-ming, YANG Gen-ke
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 10-.   https://doi.org/10.1631/jzus.2005.A0535
Abstract   PDF (0KB)
Network-induced delay and jitter are key factors causing performance degradation and instability of NCSs (networked control systems). The relationships between the sampling periods of the control loops, network-induced delay and jitter were studied aimed at token-type networks. A jitter-dependent optimal bandwidth scheduling algorithm for NCSs is proposed, which tries to achieve a tradeoff between bandwidth occupancy and system performance. Simulation tests proved the effectiveness of this optimal scheduling algorithm.
Neural network and genetic algorithm based global path planning in a static environment
DU Xin, CHEN Hua-hua, GU Wei-kang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 12-.   https://doi.org/10.1631/jzus.2005.A0549
Abstract   PDF (0KB)
Mobile robot global path planning in a static environment is an important problem. The paper proposes a method of global path planning based on neural network and genetic algorithm. We constructed the neural network model of environmental information in the workspace for a robot and used this model to establish the relationship between a collision avoidance path and the output of the model. Then the two-dimensional coding for the path via-points was converted to one-dimensional one and the fitness of both the collision avoidance path and the shortest distance are integrated into a fitness function. The simulation results showed that the proposed method is correct and effective.
Monotone routing in multirate rearrangeable logd(N,m,p) network
WANG Yang, HWANG Frank K.
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 13-.   https://doi.org/10.1631/jzus.2005.A0555
Abstract   PDF (0KB)
The construction of multirate rearrangeable network has long been an interesting problem. Of many results published, all were achieved on 3-stage Clos network. The monotone routing algorithm proposed by Hu et al.(2001) was also first applied to 3-stage Clos network. In this work, we adopt this algorithm and apply it to logd(N,m,p) networks. We first analyze the properties of logd(N,m,p) networks. Then we use monotone algorithm in logd(N,0,p) network. Furthermore we extend the result to construct multirate rearrangeable networks based on logd(N,m,p) network (1£m£n-1).
A heuristic method for solving triangle packing problem
CHEN Chuan-bo, HE Da-hua
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 15-.   https://doi.org/10.1631/jzus.2005.A0565
Abstract   PDF (0KB)
Given a set of triangles and a rectangle container, the triangle packing problem is to determine if these triangles can be placed into the container without overlapping. Triangle packing problem is a special case of polygon packing problem and a
KRBKSS: a keyword relationship based keyword-set search system for peer-to-peer networks
ZHANG Liang, ZOU Fu-tai, MA Fan-yuan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 17-.   https://doi.org/10.1631/jzus.2005.A0577
Abstract   PDF (0KB)
Distributed inverted index technology is used in many peer-to-peer (P2P) systems to help find rapidly document in which a given word appears. Distributed inverted index by keywords may incur significant bandwidth for executing more complicated s
Self-organized architecture for outdoor mobile robot navigation
ZHANG Huan-cheng, ZHU Miao-liang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 18-.   https://doi.org/10.1631/jzus.2005.A0583
Abstract   PDF (0KB)
This paper proposed a multi-agent based architecture for outdoor mobile robot navigation where event-driven control is used to handle the dynamically changing of the environment. With the support of a distributed communication infrastructure and an event-driven situation evaluation agent, the robot can initiate action adaptive to the dynamical changes in the environment through reorganize its internal architecture. Adaptiveness and feasibility of the proposed architecture is validated through navigation experiments on the robot in a variety of natural outdoor environments.
Semi on-line scheduling for maximizing the minimum machine completion time on three uniform machines
LUO Run-zi, SUN Shi-jie
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 19-.   https://doi.org/10.1631/jzus.2005.A0591
Abstract   PDF (0KB)
The paper investigates a semi on-line scheduling problem wherein the largest processing time of jobs done by three uniform machines M1, M2, M3 is known in advance. A speed si (s1=1, s2=r, s3=s, 1£r£s) is associated with machine Mi. Our goal is to maximize Cmin-the minimum workload of the three machines. We present a min3 algorithm and prove its competitive ratio is max{r+1,(3s+r+1)/(1+r+s)}, with the lower bound being at least max{2,r}. We also claim the competitive ratio of min3 algorithm cannot be improved and is the best possible for 1£s£2, r=1.
Low power implementation of datapath using regularity
LAI Li-ya, LIU Peng
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 20-.   https://doi.org/10.1631/jzus.2005.A0596
Abstract   PDF (0KB)
Datapath accounts for a considerable part of power consumption in VLSI circuit design. This paper presents a method for physical implementation of datapath to achieve low power consumption. Regularity is a characteristic of datapath and the key of the proposed method, where synthesis is tightly combined with placement to make full use of regularity, so that low power consumption is achieved. In This paper, a new concept of Synthesis In Relative Placement (SIRP) is given to deal with the semi-regularity in some datapath. Experimental results of a sample circuit validated the proposed method.
LDPC based differential unitary space-frequency coding for MIMO-OFDM systems
JIANG Hai-ning, LUO Han-wen, TIAN Ji-feng, SONG Wen-tao, LIU Xing-zhao
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 22-.   https://doi.org/10.1631/jzus.2005.A0607
Abstract   PDF (0KB)
This paper proposes a novel LDPC based differential unitary space-frequency coding (DUSFC) scheme for MIMO-OFDM systems when neither the transmitter nor the receiver has access to the channel state information (CSI). The new DUSFC strategy basic
An efficient training sequences strategy for channel estimation in OFDM systems with transmit diversity
SONG Bo-wei, GUAN Yun-feng, ZHANG Wen-jun
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6( 6): 23-.   https://doi.org/10.1631/jzus.2005.A0613
Abstract   PDF (0KB)
This paper deals with channel estimation for orthogonal frequency-division multiplexing (OFDM) systems with transmit diversity. Space time coded OFDM systems, which can provide transmit diversity, require perfect channel estimation to improve communication quality. In actual OFDM systems, training sequences are usually used for channel estimation. The authors propose a training based channel estimation strategy suitable for space time coded OFDM systems. This novel strategy provides enhanced performance, high spectrum efficiency and relatively low computation complexity.
19 articles

NoticeMore

Links