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A low-power Rijndael S-Box based on pass transmission gate and composite field arithmetic
ZENG Yong-hong, ZOU Xue-cheng, LIU Zheng-lin, LEI Jian-ming
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1553-1559.
https://doi.org/10.1631/jzus.2007.A1553
Using composite field arithmetic in Galois field can result in the compact Rijndael S-Box. However, the power consumption of this solution is too large to be used in resource-limited embedded systems. A full-custom hardware implementation of composite field S-Box is proposed for these targeted domains in this paper. The minimization of power consumption is implemented by optimizing the architecture of the composite field S-Box and using the pass transmission gate (PTG) to realize the logic functions of S-Box. Power simulations were performed using the netlist extracted from the layout. HSPICE simulation results indicated that the proposed S-Box achieves low power consumption of about 130 μW at 10 MHz using 0.25 μm/2.5 V technology, while the consumptions of the positive polarity reed-muller (PPRM) based S-Box and composite field S-Box based on the conventional CMOS logic style are about 240 μW and 420 μW, respectively. The simulations also showed that the presented S-Box obtains better low-voltage operating property, which is clearly relevant for applications like sensor nodes, smart cards and radio frequency identification (RFID) tags.
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A four spiral slots microstrip patch antenna for radiotelemetry capsules based on FDTD
HUANG Biao, YAN Guo-zheng, LI Qian-ru
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1560-1567.
https://doi.org/10.1631/jzus.2007.A1560
Antenna is very crucial to radiotelemetry capsules which can measure the physiological parameters of the gastrointestinal (GI) tract. The objective of this paper is to design a novel spiral slots microstrip patch antenna for the radiotelemetry capsules communicating with external recorder at 915 MHz located in ISM (Industry, Science, and Medical) bands. The microstrip patch antenna is designed and evaluated using the finite-difference time-domain (FDTD) method. Return loss characteristics and the effect of the human body on resonant frequency are analyzed, and the performances of radiation patterns at different positions of the human alimentary tract are also estimated. Finally, specific absorption rate (SAR) computations are performed, and the peak 1-g and 10-g SAR values are calculated. According to the peak SAR values, the maximum delivered power for the designed antenna was found so that the SAR values of the antenna satisfy the ANSI (American National Standards Institute) limitations.
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A new broadband differential phase shifter fabricated using a novel CRLH structure
ZOU Yong-zhuo, LIN Zhi-li, LING Ti, YAO Jun, HE Sailing
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1568-1572.
https://doi.org/10.1631/jzus.2007.A1568
Broadband phase shifters are mostly proposed and fabricated based on the scheme proposed by Shiffman, which uses a coupled line with far ends connected together and a uniform transmission line to give a differential phase shift. Based on the unique dispersion property of the composite right/left-handed (CRLH) metamaterial structure, a new configuration is presented in this paper for fabricating the broadband differential phase shifter, which employs a novel CRLH metamaterial structure as one of the differential phase-shift arms, instead of the conventional coupled line. The new circuit can achieve a phase shift of 90° in an operational bandwidth as broad as one octave and its phase deviations are quite small. An original design of the novel broadband phase shifter is presented, in which the artificial CRLH structure was implemented by microstrip quasi-lumped elements. Both the simulated and measured results of the 90° broadband differential phase shifter are presented.
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A wireless solution for greenhouse monitoring and control system based on ZigBee technology
ZHANG Qian, YANG Xiang-long, ZHOU Yi-ming, WANG Li-ren, GUO Xi-shan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1584-1587.
https://doi.org/10.1631/jzus.2007.A1584
With the rapid development of wireless technologies, it is possible for Chinese greenhouses to be equipped with wireless sensor networks due to their low-cost, simplicity and mobility. In the current study, we compared the advantages of ZigBee with other two similar wireless networking protocols, Wi-Fi and Bluetooth, and proposed a wireless solution for greenhouse monitoring and control system based on ZigBee technology. As an explorative application of ZigBee technology in Chinese greenhouse, it may promote Chinese protected agriculture.
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Path tracking control of autonomous agricultural mobile robots
ZHU Zhong-xiang, CHEN Jun, YOSHIDA Toyofumi, TORISU Ryo, SONG Zheng-he, MAO En-rong
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1596-1603.
https://doi.org/10.1631/jzus.2007.A1596
In a tractor automatic navigation system, path planning plays a significant role in improving operation efficiency. This study aims to create a suboptimal reference course for headland turning of a robot tractor and design a path-tracking controller to guide the robot tractor along the reference course. A time-minimum suboptimal control method was used to generate the reference turning course based on the mechanical parameters of the test tractor. A path-tracking controller consisting of both feedforward and feedback component elements was also proposed. The feedforward component was directly determined by the desired steering angle of the current navigation point on the reference course, whereas the feedback component was derived from the designed optimal controller. Computer simulation and field tests were performed to validate the path-tracking performance. Field test results indicated that the robot tractor followed the reference courses precisely on flat meadow, with average and standard lateral deviations being 0.031 m and 0.086 m, respectively. However, the tracking error increased while operating on sloping meadow due to the employed vehicle kinematic model.
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Gaussian particle filter based pose and motion estimation
WU Xue-dong, SONG Zhi-huan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1604-1613.
https://doi.org/10.1631/jzus.2007.A1604
Determination of relative three-dimensional (3D) position, orientation, and relative motion between two reference frames is an important problem in robotic guidance, manipulation, and assembly as well as in other fields such as photogrammetry. A solution to pose and motion estimation problem that uses two-dimensional (2D) intensity images from a single camera is desirable for real-time applications. The difficulty in performing this measurement is that the process of projecting 3D object features to 2D images is a nonlinear transformation. In this paper, the 3D transformation is modeled as a nonlinear stochastic system with the state estimation providing six degrees-of-freedom motion and position values, using line features in image plane as measuring inputs and dual quaternion to represent both rotation and translation in a unified notation. A filtering method called the Gaussian particle filter (GPF) based on the particle filtering concept is presented for 3D pose and motion estimation of a moving target from monocular image sequences. The method has been implemented with simulated data, and simulation results are provided along with comparisons to the extended Kalman filter (EKF) and the unscented Kalman filter (UKF) to show the relative advantages of the GPF. Simulation results showed that GPF is a superior alternative to EKF and UKF.
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MRI and PET images fusion based on human retina model
DANESHVAR Sabalan, GHASSEMIAN Hassan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1624-1632.
https://doi.org/10.1631/jzus.2007.A1624
The diagnostic potential of brain positron emission tomography (PET) imaging is limited by low spatial resolution. For solving this problem we propose a technique for the fusion of PET and MRI images. This fusion is a trade-off between the spectral information extracted from PET images and the spatial information extracted from high spatial resolution MRI. The proposed method can control this trade-off. To achieve this goal, it is necessary to build a multiscale fusion model, based on the retinal cell photoreceptors model. This paper introduces general prospects of this model, and its application in multispectral medical image fusion. Results showed that the proposed method preserves more spectral features with less spatial distortion. Comparing with hue-intensity-saturation (HIS), discrete wavelet transform (DWT), wavelet-based sharpening and wavelet-à trous transform methods, the best spectral and spatial quality is only achieved simultaneously with the proposed feature-based data fusion method. This method does not require resampling images, which is an advantage over the other methods, and can perform in any aspect ratio between the pixels of MRI and PET images.
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Pattern design on 3D triangular garment surfaces
WANG Jin, LU Guo-dong, LI Ji-tuo, CHEN Long, ZHANG Dong-liang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1642-1649.
https://doi.org/10.1631/jzus.2007.A1642
This paper focuses on a pattern design method for a 3D triangular garment surface. Firstly, some definitions of 3D style lines are proposed for designing the boundaries of patterns as drawing straight lines or splines on the triangular surface. Additionally some commonly used style lines are automatically generated to enhance design efficiency. Secondly, after style lines are preprocessed, a searching method is presented for quickly obtaining the boundaries and patches of a pattern on the 3D triangular surface. Finally a new pattern design reuse method is introduced by encoding/decoding the style line information. After style lines are encoded, the pattern design information can be saved in a pattern template and when decoding this template on a new garment surface, it automates the pattern generation for made-to-measure apparel products.
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Constrained multi-degree reduction of rational Bézier curves using reparameterization
CAI Hong-jie, WANG Guo-jin
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1650-1656.
https://doi.org/10.1631/jzus.2007.A1650
Applying homogeneous coordinates, we extend a newly appeared algorithm of best constrained multi-degree reduction for polynomial Bézier curves to the algorithms of constrained multi-degree reduction for rational Bézier curves. The idea is introducing two criteria, variance criterion and ratio criterion, for reparameterization of rational Bézier curves, which are used to make uniform the weights of the rational Bézier curves as accordant as possible, and then do multi-degree reduction for each component in homogeneous coordinates. Compared with the two traditional algorithms of “cancelling the best linear common divisor” and “shifted Chebyshev polynomial”, the two new algorithms presented here using reparameterization have advantages of simplicity and fast computing, being able to preserve high degrees continuity at the end points of the curves, do multi-degree reduction at one time, and have good approximating effect.
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Relation among C-curve characterization diagrams
CAO Juan, WANG Guo-zhao
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1663-1670.
https://doi.org/10.1631/jzus.2007.A1663
As three control points are fixed and the fourth control point varies, the planar cubic C-curve may take on a loop, a cusp, or zero to two inflection points, depending on the position of the moving point. The plane can, therefore, be partitioned into regions labelled according to the characterization of the curve when the fourth point is in each region. This partitioned plane is called a “characterization diagram”. By moving one of the control points but fixing the rest, one can induce different characterization diagrams. In this paper, we investigate the relation among all different characterization diagrams of cubic C-curves based on the singularity conditions proposed by Yang and Wang (2004). We conclude that, no matter what the C-curve type is or which control point varies, the characterization diagrams can be obtained by cutting a common 3D characterization space with a corresponding plane.
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Topology evolutions of silhouettes
DAI Jun-fei, KIM Junho, ZENG Hua-yi, GU Xian-feng, YAU Shing-tung
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2007, 8(10): 1671-1680.
https://doi.org/10.1631/jzus.2007.A1671
We give the topology changing of the silhouette in 3D space while others study the projections in an image. Silhouettes play a crucial role in visualization, graphics and vision. This work focuses on the global behaviors of silhouettes, especially their topological evolutions, such as splitting, merging, appearing and disappearing. The dynamics of silhouettes are governed by the topology, the curvature of the surface, and the view point. In this paper, we work on a more theoretical level to give enumerative properties of the silhouette including: the integration of signed geodesic curvature along a silhouette is equal to the view cone angle; in elliptic regions, no silhouette can be contained in another one; in hyperbolic regions, if a silhouette is homotopic to a point, then it has at least 4 cusps; finally, critical events can only happen when the view point is on the aspect surfaces (ruled surface of the asymptotic lines of parabolic points with surface itself). We also introduce a method to visualize the evolution of silhouettes, especially all the critical events where the topologies of the silhouettes change. The results have broad applications in computer vision for recognition, graphics for rendering and visualization.
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21 articles
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