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24 June 2011, Volume 17 Issue 3
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Communication and Information
Analysis of Very Minimum Chirp Keying Signals with Continuous Phase Modulation Characteristics
JIANG Jun-Chao, ZHENG Guo-Shen, QIU Zhi-Yi, LIU Ya-Jun
2011, 17(3): 221-226. doi:
10.3969/j.issn.1007-2861.2011.03.001
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The very minimum chirp keying (VMCK) modulation possesses characteristics of an ultra narrow band (UNB). This paper uses a general analysis method of continuous phase modulation (CPM) to select a linear signal as the integral pulse, give the continual phase modulation express of VMCK, and construct a new kind of the VMCK transmitter structure. The normalization power spectral density formula of VMCK is then derived, with the power percentage bandwidth as an inspection criterion. It is proven that, for an orthogonal binary signal set, VMCK has a narrower main lobe compared with the minimum shift keying (MSK) modulation. Therefore better band width efficiency can be achieved with VMCK.
Environmental and Chemical Engineering
Caplanar Stripline Fed Triple-Band High-Gain Microstrip Antenna
ZHOU Jun, YANG Xue-Xia, LV Yan-Jing
2011, 17(3): 227-231. doi:
10.3969/j.issn.1007-2861.2011.03.002
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A microstrip antenna fed by a coplanar stripline (CPS) working at 2.4, 3.5 and 5.8 GHz with a simple structure and a high gain is proposed. Multifrequency operation is realized by introducing a pair of small hoops in the center of the rhombic structure. The gain is improved by placing a metal reflector beneath the substrate. A CPS to microstrip Balun is designed for measurements and more applications. The measuring results agree well with simulation, which meet the demand of practical applications. Gains of all operating frequencies are higher than 10 dB.
Dynamic Markov Chain Monte Carlo Detection Based on Multiple Input- Multiple Output Orthogonal Frequency Division Multiplexing Systems
YANG Hui-Lian, YANG Jian-Guo, SHI Hai
2011, 17(3): 232-237. doi:
10.3969/j.issn.1007-2861.2011.03.003
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In multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems, the Bayesian multiuser detection scheme based on the Markov chain Monte Carlo (MCMC) method has good performance in suppressing multipath fading, carrier frequency offset and phase noise. The algorithm, however, cannot find its application in real-time due to a low convergence rate. To solve this problem, we propose a new method called dynamic MCMC detection. Correlation between samples of the system state and the threshold decided on convergence are used to dynamically select the convergence region about the samples of the system state in an iterative operation. This improves capability of real time operations and maintains the performance of the algorithm. Simulation results show that the proposed method has a higher convergence rate and lower bit error rate.
Recognition of Beverage Bottles Based on Corner and Local Features
HUANG Dong-Jin, ZHANG Qian, WU Jiong, DING You-Dong
2011, 17(3): 238-242. doi:
10.3969/j.issn.1007-2861.2011.03.004
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In this work, the machine vision technique is introduced into an automated beverage bottle reclaiming system. Based on the characteristics of beverage bottles made of PET materials, local features and geometrical invariability, we extract the corner points at subpixel accuracy, define the curve angle around the central corner and its sign as the eigenvalues of a beverage bottle, and propose a blockmatching algorithm. Experimental results show that the algorithm is stable, and has good discrimination capability, high recognition rate and fast computation speed. It can meet the requirements of reclaiming beverage bottles accurately in real time.
Mechatronics Engineering and Automation
Rehabilitation Robot Mechanism for Finger Tapping Movement Tracing
SHU Jing-Jing, JIAN Jin-Wu, CHEN Lin-Yong, ZHANG E-Nan
2011, 17(3): 243-248. doi:
doi:10.3969/j.issn.1007-2861.2011.03.005
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In this research a finger rehabilitation training robot is designed according to the continuous passive motion (CPM) rehabilitation theroy. Based on an analysis of the finger structure and movement trajectory, an optotrak certus motion capture system is used to acquire trajectory parameters of the finger tip movement. The atlas method is employed to accomplish mechanism dimensional synthesis of the finger rehabilitation training robot. Feasibility of the mechanism is verified using a modeling and simulation method with Simulink.
Modified Variable Step Algorithm of Maximum Power Point Tracking for Photovoltaic System
WANG Xi-Fei, TUN Wei, ZHANG Hao-Hua, XU Yue
2011, 17(3): 249-252. doi:
10.3969/j.issn.1007-2861.2011.03.006
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Computer simulation for the silicon solar cells is established using Matlab/Simulink. The output characteristics and maximum power point tracking (MPPT) curve are calculated. A new criterion based on the traditional perturbation and observation (P&O) method is given, with which a control module of solar cells is designed. Simulation results indicate that this module can adapt to the rapid changes in temperature and light, track the maximum power point much better than the traditional methods in speed and stabilities.
Shape and Position Detection of Search and Rescue Robot Used in Ruins
TU Jian-Nai, CHEN Lin-Yong, ZHANG Shen, ZHANG E-Nan
2011, 17(3): 253-258. doi:
10.3969/j.issn.1007-2861.2011.03.007
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This paper presents a method of spatial shape rebuilding and target positioning for a robot used in searching and rescuing lives in ruins. In order to rebuild a spatial curve representing the shape of the robot body which is 3.5 m long, a long curvature sensor is designed based on fiber Bragg grating (FBG) to detect spatial curvature information, and the spatial curve fitting is realized based on these discrete spatial curvatures. After shape rebuilding, this paper realizes searching and rescuing target positioning using a threeaxis electronic compass to detect posture of the datum point of shape rebuilding. Experimental data show that the targeting error is about 10 cm which basically meets the target positioning requirements of robots. With the posture detection of a threeaxis electronic compass, the shape and position detection system becomes more effective and practical.
Mathematics.Physics and Chemistry
Unweighted 1-Center Problem on Block Graphs
ZHANG Xiao-Qin, KANG Li-Yang
2011, 17(3): 259-262. doi:
10.3969/j.issn.1007-2861.2011.03.008
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In the pcenter problem, p facilities are located in the network such that the maximum weighted distance from a client to its nearest facility is minimized. If all client weights are equal to 1, it is called an unweighted center problem. Unweighted 1-center problem is studied on block graphs with a unit edge length. It is shown that the problem can be solved in linear time using the tree structure of a block graph.
Centrosymmetric Tridiagonal Least Square Solution to Matrix Equation
ZHANG Xiang, WANG Qing-Wen
2011, 17(3): 263-265. doi:
doi:10.3969/j.issn.1007-2861.2011.03.009
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The matrix equation 〖WTHX〗AX〖WTBX〗=〖WTHX〗B〖WTBZ〗 is considered, and a necessary and sufficient condition for the existence of centrosymmetric tridiagonal solutions is given. A new result of the following problem is obtained which related to the leastsquares solutions of 〖WTHX〗AX〖WTBX〗=〖WTHX〗B〖WTBZ〗 for 〖WTHX〗X〖WTBZ〗: given 〖WTHX〗A, B〖WTBZ〗∈〖WTHX〗R〖WTBX〗m×n,〖WTBZ〗 find a centrosymmetric tridiagonal matrix 〖WTHX〗X〖WTBZ〗∈〖WTHX〗R〖WTBX〗m×n〖WTBZ〗 such that ‖〖WTHX〗AX〖WTBZ〗-〖WTHX〗B〖WTBZ〗‖ is minimal.
Gaussian Isotropic Convex Bodies
WANG Lei, HE Bin-Wu
2011, 17(3): 266-269. doi:
10.3969/j.issn.1007-2861.2011.03.010
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Gaussian isotropic bodies and Gaussian isotropic constants were defined, and the existence and orthogonal invariability of Gaussian isotropic bodies were proved. By calculating the Gaussian isotropic constants of a ball and a cube, both with unit volume, we show that changes in the Gaussian isotropic constants in the Gaussian measure are opposite to those in the Lebesgue measure.
New Method to Solve High-Dimensional Nonlinear Evolution Equations with Symbolic Computation
SHI Zhen-Hua, XIA Tie-Cheng
2011, 17(3): 270-274. doi:
doi:10.3969/j.issn.1007-2861.2011.03.11
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In this paper, we seek exact solutions to the (2+1)dimensional Bogoyavlenskii’s breaking soliton equation and (3+1) dimensional KadomtsevPetviashvili (K-P) equation by G′/Gexpansion method, and obtain non-traveling wave solutions including hyperbolic function solutions, trigonometric function solutions and rational solutions. The method is effective for high-dimensional NLPDEs in mathematical physics.
Error Estimate of Legendre Tau Method for Two-Dimensional Poisson Equation
SHEN Ting-Ting, MA He-Beng
2011, 17(3): 275-279. doi:
doi:10.3969/j.issn.1007-2861.2011.03.012
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The two-dimensional Poisson equation with homogeneous Dirichlet boundary condition by the Legendre tau method is considered. The optimal rate of convergence in H1norm of Legendre tau method for the two-dimensional Poisson equation with homogeneous Dirichlet boundary condition is obtained by taking test functions with the generalized Jacobi weight. The optimal convergent rate in Lnorm is proved by the duality argument. Numerical examples are given to verify the analysis results.
Limit Symmetry of Sine-Gordon Equation and Applications
SHEN Jing, ZHAO Song-Lin, ZHANG Da-Jun
2011, 17(3): 280-285. doi:
10.3969/j.issn.1007-2861.2011.03.013
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Limit symmetry of the sine-Gordon equation and its applications are considered. The similarity reduction leads to limit solutions of the sineGordon equation. Besides, based on the relationship between symmetries and sources of soliton equations, a sine-Gordon equation with new selfconsistent sources is obtained and its solutions are derived.
Sufficient Conditions for a Factorized Group to be Supersolvable
QIAN Wei, GUO Xiu-Yun
2011, 17(3): 286-288. doi:
10.3969/j.issn.1007-2861.2011.03.014
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Let A and B be subgroups of a finite group G and G=AB. Some sufficient conditions are obtained for G to be supersolvable if the length of conjugacy class of every element in A∪B is squarefree.
Upper Bounds of Maximum Distance Separable Codes
YANG Jian-Sheng, ZHANG Yun-Ying, WANG De-Xiu
2011, 17(3): 289-292. doi:
doi:10.3969/j.issn.1007-2861.2011.03.015
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Let Mq(k) be the maximum length of qary (n,qk,d) maximum distance separable （MDS） codes with parameters q and k. Properties of Mq(k) are studied, and some new upper bounds of Mq(k) are obtained.
Material Science
Effect of Water Chemistry and Corrosion Temperature on Compressive Stress of Oxide Films on Zirconium Alloys
GENG Jian-Qiao, ZHOU Bang-Xin, YAO Mei-Yi, WANG Jin-Gong, ZHANG Xin, LI Shi-Lu, DU Chen-Xi
2011, 17(3): 293-296. doi:
10.3969/j.issn.1007-2861.2011.03.016
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To investigate the effect of corrosion temperature and water chemistry on compressive stress with the increase of oxide film thickness, Zr4 and N18 tubular specimens were corroded in three kinds of water chemistry. Compressive stress of oxide films formed on the outside of the tubular specimens was measured with a curling method of oxide film. Experimental results indicate that compressive stress in oxide films decreases in the sequence of 360 ℃ deionized water ＞400 ℃ super-heated steam ＞360 ℃ lithiated water. Li+ and OH- ions incorporated into the oxide films decrease the surface free energy of oxide. As a result, the diffusion of vacancies, formation of pores and development of micro-cracks are enhanced. This is the reason why compressive stress of oxide films formed in 360 ℃ lithiated water is the lowest. Diffusion of vacancies is promoted at higher temperature, resulting in relaxation of compressive stress in oxide films. Therefore compressive stress of oxide films formed in 400 ℃ super-heated steam is lower than that formed in 360 ℃ deionized water.
Behavior of Austenizing Temperature on Hardenability of P20B Steel
LI Dan, MIN Yong-An, WUN Xiao-Chun, CHEN Zhuo
2011, 17(3): 297-301. doi:
10.3969/j.issn.1007-2861.2011.03.017
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The C curve of supercooled austenite of plastic mould steel P20B was investigated with the DIL805A dilatometric instrument. The austenitizing temperature was between 850 ℃ and 1 000 ℃ and the isothermal temperature between 640 ℃ and 720 ℃. We compared austenite grain size at different austenitizing temperatures and analyzed the second phase which obtained from the electrolytic extraction procedure. The results show that at 850~920 ℃ in the temperature range when the austenitizing temperature is increased, the grains grow slightly, the content of B increased significantly to make the C curve strongly shift right. At 920~1 000 ℃ in the temperature range when the austenitizing temperature is increased, the grains grow significantly, and the content of B no longer increases so hardenability of P20B steel does not increased.
Environmental and Chemical Engineering
Effect of Polyethylene Glycol Multiwalled Carbon Nanotubes to Plasmid DNA
LAO Wen-Yan, SHANG Ying-Hui, JIAO Zheng, LAO Feng-Xue
2011, 17(3): 302-306. doi:
doi:10.3969/j.issn.1007-2861.2011.03.018
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The biocompatibility of pristine multiwalled carbon nanotubes (MWNTs), purified MWNTs and polyethylene glycol MWNTs (PEGMWNTs) was studied using the method of plasmid DNA assay and atomic force microscopy (AFM). The results show that pristine MWNTs can cause serious damage to plasmid DNA. After purification, MWNTs may cause less damage to plasmid DNA, while at the same concentration level, PEGMWNTs cause the smallest damage to plasmid DNA.
Civil Engineering
Analytical Solution and Numerical Simulation for Plane Strain Bifurcation in Constitutive Model for Over-Consolidated Clays
SUN De-An, DUAN Bo, ZHEN Wen-Zhan
2011, 17(3): 307-313. doi:
10.3969/j.issn.1007-2861.2011.03.019
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A fundamental problem concerning the theory of strain localization is the condition of the occurrence of localization bifurcation. Based on the Hvorslev envelopebased three-dimensional elastoplastic constitutive model for overconsolidated clay, an analytical solution of bifurcation and the expression of inclination angle for shear band caused by localization bifurcation are derived for strain localization in plane strain stress states. Meanwhile, influences of overconsolidation ratio (OCR) on the analytical solution and the inclination angle are analyzed. The theoretical analysis shows that onset of localization bifurcation occurs in the hardening regime under the plane strain conditions and, with strain localization expanding, the change in inclination angle of shear band is striking before bifurcation and steady thereafter. On the other hand, numerical simulation of plane strain tests on the isotropically homogenous cubic specimen for the bifurcation is carried out by using a finite element analysis software ABAQUS with the model implemented. Numerical solutions exhibit a good overall agreement with analytical solutions for the bifurcation onset, indicating that the analytical solutions are reasonable.
One-Dimensional Consolidation Behavior of Unsaturated Soils under Two Boundary Conditions
QIN Ai-Fang, YANG Liu-Ping, SUN De-An, JIANG Rui
2011, 17(3): 314-319. doi:
10.3969/j.issn.1007-2861.2011.03.020
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Aiming at the engineering practice in special circumstances, one-dimensional consolidation of unsaturated land-based issues under compression is studied considering the boundary conditions that the surface is air infiltration water impermeable and the underside is impermeable. Based on the onedimensional consolidation theory of Fredlund unsaturated soils, appropriate assumptions are made. Applying Laplace transform and the CayleyHamilton theorem to the liquid and vapor control equations, and Darcy’s law and Fick’s law, the transfer function between top of the state vector and any depth of the state vector is constructed. By introducing boundary conditions, excess pore water pressure and excess pore air pressure are derived in the Laplace domain. Using the Crump method, inverse Laplace transform is performed, and a semi-analytical solution to the excess pore water pressure and excess pore air pressure obtained in the time domain. Typical examples are given to show changes in excess poreair pressure, excess porewater pressure and degrees of consolidation with the time under different conditions of airwater coefficient rate of penetration. These results are useful for the research of characteristics of unsaturated soils one-dimensional consolidation.
Effect of Pile Pulling in Casing on Established Large Diameter Waste Pipe
SONG Hui, CHANG Ying, HUANG Chao, ZHANG Meng-Chi
2011, 17(3): 320-324. doi:
10.3969/j.issn.1007-2861.2011.03.021
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Effects of pile pulling on the surrounding structures is a common problem in construction projects. The effect can be reduced substantially if piles are pulled in casing. The overall process is divided into three stages including steel casing pressing, pile pulling, and steel casing pulling accompanied by refilling. We take an abandoned pile in Shanghai Rail Transit Line 7 as an example to study the effect on an established large waste pipe during pile pulling in casing. In the study, we use the general purpose finite element program ABAQUS based on the elastic stressstrain theory. The soil is simulated according to the Drucker-Prager elastic-plasticity stress-strain theory. It is shown that the horizontal and vertical displacement increases with the increase of casing depth during the pilepressing process, while with the decrease of casing depth during pile pulling process. The displacement of horizontal direction is one tenth of that of vertical direction. Comparison between the simulation results and the monitored data shows that the simulation is useful to the construction.
Numerical Simulation of Squeezed Branch and Plate Pile and Application to Balance Design for Variable Rigidity
MI Xiao-Qing, ZHU Jie-Jiang
2011, 17(3): 325-330. doi:
doi:10.3969/j.issn.1007-2861.2011.03.022
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Differential settlement of composite foundation cannot be ignored, and often brings undesirable internal force to the structure. Traditional solutions are to change length, spacing, and diameter of the pile to achieve even foundation stiffness. Squeezed branch pile is a new type of pile with high pile capacity and low settlement. This paper simulates the interaction between squeezed branch pile and soil using the finite difference analysis software FLAC 3D, and get the best solution to reduce, or even eliminate, differential settlement, leading to a more reasonable structural arrangement.
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