Table of Content

30 June 2006, Volume 13 Issue 3

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Articles

Large-Bandwidth Patch Antenna with Ridge-Shaped Ground Plate


ZHANG Jun-wen;WU Qiang;ZHONG Shun-shi;XU Sai-qing;

2006, 13(3):  221-223 . 

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novel large-bandwidth square patch antenna with ridge-shaped ground plate is proposed. The patch is on an air substrate and excited by a coaxial probe that is stretched from the top of a ridge-shaped ground plate so that the probe inductance is reduced and the broadband operation is obtained. The measured impedance bandwidth with VSWR≤2 reaches 90.1%, covering a frequency range of 1.75～4.62 GHz.

Window-Scaling: An Improved Image Scaling Algorithm Using Bilinear Interpolation

ZUO Xiao;RAN Feng;XU Mei-hua

2006, 13(3):  224-227 . 

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In this paper, we discuss a bilinear interpolation and window-scalingalgorithm for image scaling. The proposed algorithm using a bilinear method has a good high frequency response. Different algorithms including nearest interpolation are compared. Hardware implementation of the proposed algorithm is achieved with FPGA. It has been shown to have a good scaling property with low hardware consumption.

General Methods for X-Ray Projection Simulation in Image Reconstruction

HUANG Jian-lin;LU Dong-hui

2006, 13(3):  228-233 . 

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Cone-beam CT is an important research topic in image reconstruction. The first thing to do in the study of image reconstruction algorithm is to acquire projections. This paper presents several general methods of X-ray projection simulation, and discusses conditions under which different methods are applicable. Experiments are carried out to compare the pros and cones of these approaches when used in projection acquisition. The results show that projections acquired with analytic and vector methods are rigorous for regular and homogeneous objects, and projections acquired with discrete methods are acceptable for irregular and inhomogeneous objects in image reconstruction.

Design of 2.4～2.5 GHz Frequency Source Controlled by I 2C-Bus

WANG Xiang-yong;LI Ming-xiang;GE Jian-min;HAN Jian-guo;DING Zong-wen

2006, 13(3):  234-238 . 

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S-band phase locked model frequency synthesizers are summarized. The frequency range is from 2.4 to 2.5 GHz with a 4 MHz step. The phase noise is ￡(100 kHz) <-110 dBc/Hz. The frequency synthesizer uses an I 2C-bus to control a series of parameters of phase locked loop via a 51-series microcontroller. The division ratio of feedback signal of VCO is realized through software programming instead of traditional PC control, making applications more convenient. This circuit is featured by small size and easyadjustment of operating frequency.

Front-End of 0.25 μm CMOS RF Receiver for Bluetooth

XU Liang;WANG Wen-qi;TANG Xue-feng;ZHAN Fu-chun

2006, 13(3):  239-243 . 

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A 0.25 μm CMOS RF receiver frontend for Bluetooth in TSMC 0.25 μm CMOS process is designed. It includes a differential LNA, two mixers and a polyphase filter that generates a quadrature signal. The receiver frontend is simulated with Cadence SpectreRF. The supply voltage is 2.5 V, gain of the receiver front-end is 21 dB, noise figure is 7 dB, P 1 dB is -21.3 dBm, IIP3 is -9.78 dBm, and the total current is 16.1 mA.

Efficient Feature Extraction in an Attendance System -Based on Face Recognition

ZHANG Ting;ZHU Qiu-yu;ZHU Jun-lin

2006, 13(3):  244-248 . 

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A face recognition method applicable to attendance systems is proposed. Areas of a face image are first segmented from facial frontal and facial profile images that are dynamically captured with a camera. Effective geometric feature points extracted from the face regions are then used to construct feature vectors. These feature vectors are compared with the vector information in the card held by the subject. The algorithm is simple, and a high recognition rate has been achieved in the experiments.

Problem of Nonlinear One-Dimensional p-Laplace Equation with Boundary Conditions

CHEN Jia-jia;WANG Yuan-di

2006, 13(3):  249-255 . 

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Existence of positive solution for one-dimensional p-Laplace equation with multipoint boundary value and integral boundary conditions are considered. The eigenvalue problem of linear equation with three-point boundary value is also studied.

A Strengthened Hardy-Hilbert Type Inequality

YANG Bi-cheng

2006, 13(3):  256-259 . 

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By obtaining an inequality of the weight coefficient, a strengthened HardyHilbert type inequality and its dual form are established.The strengthened equivalent forms are considered.

Existence of Random Attractor for Strongly Damped-Stochastic sine-Gordon Equation

YIN Fu-qi;ZHOU Sheng-fan;LI Hong-yan

2006, 13(3):  260-265 . 

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A strongly damped stochastic sineGordon equation is considered. By introducing weight norm and splitting positivity of the linear operator in the corresponding evolution equation of the first order with respect to time, existence of a compact random attractor is shown for a stochastic dynamical system generated by strongly damped sineGordon equations with white noise.

Nano-Thermomechanical Deformation of a Microcantilever Laminated Beam in Label-Free Biodetection

XING Jing-jing;ZHANG Neng-hui;ZHENG Jin-

2006, 13(3):  266-268 . 

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Abandoning the uniaxial stress assumption, a continuum laminated beam model in terms of deflection induced by labelfree biodetections is set up to study nanomechanical behaviors of a biodetector subjected to hybridization surface stresses and thermal loads. Linear and uniform temperature fields are used separately to simulate transient and steady temperature distributions in biochemical reactions in order to explain the bimetallic effects in Fritz's experiments on DNA hybridizations.

Monte-Carlo Simulation for Ratchet Wall of Synchrotron Radiation Facility

WEI Zhong-yuan;LUO Wen-yun

2006, 13(3):  269-272 . 

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A ratchet-shielding wall is the main part of shielding in a synchrotron facility. A storage ring induced by 3.5 GeV and 300 mA electron beam is taken as an example to discuss calculation of ratchetshielding walls. EGSnrc based on the Monte-Carlo simulation is used to determine the shielding requirements for a ratchet-shielding wall.

Applicability of Turbulent Models in Simulation of Internal Flow within Axial Flow Pump

SHI Fa-jia;CHEN Hong-xun

2006, 13(3):  273-277 . 

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The internal flow within axial flow pump is a complicated turbulent flow. Based on the 3D RANS equations, the standard kε, RNG kε and realizable kε turbulent models are used in 3D numerical simulation of the interior flow within an axial flow pump with the specific speed equal to 1 000 under different operating conditions. The head and efficiency of axial flow pump are calculated and compared with experimental data. Relative errors between the calculated heads derived from different models and the experimental heads on high efficient zones of the pump are less than 4%. Different models have different characteristics deviated from optimal operating conditions.

Analysis of High Order Explicit Finite Difference Schemes for Linear Wave Equations

LUO Bai-hua

2006, 13(3):  278-282 . 

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A type of low-dissipation and low-dispersion high-order finite difference scheme is studied for computation of wave motion. An optimized sevenpoint central difference is used to approximate the spatial derivative, and two optimization methods are presented. For the time marching, the fourth order explicit RungeKutta methods (RK4 and LDDRK) are used. All effective wave-number ranges of the three spatial schemes, numerical errors of various full schemes, and minimum point numbers per wavelength (ppw) for long distance wave propagation calculation are studied. Based on the comparison, suggestions on the use of these schemes are given.