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Journal of Jiangsu University(Natural Science Eidtion)

	2011 Vol.32 Issue.3 Published 2011-05-10

	Article

Article

	249	Binocular measurement model based on fault slice perspective
		YIN Jianjun, MAO Hanping
		According to geometric analysis of binocular location, a kind of binocular measurement model based on fault slice perspective was presented in this paper. Nonlinear relation between optical parallax of object point and different depth distance was firstly established. Neural network model was established in advance on each slice plane to determine planar X and Y coordinate of object point according to known depth distance. When slice distance was different from modelling depth distance, nearest neighbor rule was adopt to model under proximate distance. The results show that maximum absolute error of model in depth direction is less than 4.5 mm, and those in X and Y directions are less than 2.0 mm. The error of spatial distance with real object point varies from 0.241 6 mm to 4.859 0 mm when 97 fault slice positions change from 223 mm to 1 183 mm. The tests of locating tomato show that the model can meet the requirement for precise locating fruit.
		2011 Vol. 32 (3): 249-253 [Abstract] ( 1826 ) [HTML 1KB] [ PDF 0KB] ( 627 )

	254	Analytical algorithm of inverse kinematics model for 7DOF manipulator
		WANG Hai, CAI Yingfeng, ZHANG Weigong
		For 7 degree of freedom (DOF) manipulator which has redundant DOF, traditional numerical algorithm based on optimal Jacobean Matrix has some obvious cons. The numerical algorithm just provides one possible solution which can not fully use the redundancy feature of the 7DOF manipulator.A new additional constraint which named elbow angle was proposed besides traditional pos matrix constraint. According to these 7 dimension constraint, a new analytical solving of inverse kinematics model for 7DOF manipulator was deduced to obtain redundant solution. In the simulation, pos control of manipulator end effector and aiming control were achieved based on this algorithm. The simulation results demonstrate high accuracy, fast computation and application value of this algorithm.
		2011 Vol. 32 (3): 254-259 [Abstract] ( 2423 ) [HTML 1KB] [ PDF 1426KB] ( 5444 )

	260	Experiment of locust phototactic response to flash and cosine alternating light
		LIU Qihang, ZHOU Qiang
		To provide theoretical reference and technical parameters for designing locusts′ LED trapping light, optimization of flash light′s frequency and cosine alternating light′s shining cycle parameter for locusts′ phototactic behavior were conducted by LED light source and phototaxis behavior trial equipment with comparison method.The efficiency difference of flash light, cosine alternating and constant light was studied，and the efficiency principle of flash light and cosine alternating light on locusts′ phototaxis behavior was also discussed.The results show that locusts′ phototactic response can be affected by spectrum, shining frequency and cycle,and violet flash light with shining interval of 30 ms has the best efficiency to locusts′ phototactic response. Cosine alternating violet light with shining cycle of 640 ms is superior to flash light and other cosine alternating light for locusts′ phototactic response.The phototactic response of flash violet light with shining interval of 30 ms is inferior to that of cosine alternating volet blue and green flash light with shining cycle of 640 ms. According to the illumination threshold of locusts′ sensitve spectrum,the efficiency range of locusts′ phototactic response can be extended by reasonable combination of cosine alternating light and flash light.
		2011 Vol. 32 (3): 260-265 [Abstract] ( 1261 ) [HTML 1KB] [ PDF 2022KB] ( 1767 )

	260	Experiment of locust phototactic response to flash and cosine alternating light
		LIU Qihang, ZHOU Qiang
		To provide theoretical reference and technical parameters for designing locusts′ LED trapping light, optimization of flash light′s frequency and cosine alternating light′s shining cycle parameter for locusts′ phototactic behavior were conducted by LED light source and phototaxis behavior trial equipment with comparison method.The efficiency difference of flash light, cosine alternating and constant light was studied，and the efficiency principle of flash light and cosine alternating light on locusts′ phototaxis behavior was also discussed.The results show that locusts′ phototactic response can be affected by spectrum, shining frequency and cycle,and violet flash light with shining interval of 30 ms has the best efficiency to locusts′ phototactic response. Cosine alternating violet light with shining cycle of 640 ms is superior to flash light and other cosine alternating light for locusts′ phototactic response.The phototactic response of flash violet light with shining interval of 30 ms is inferior to that of cosine alternating volet blue and green flash light with shining cycle of 640 ms. According to the illumination threshold of locusts′ sensitve spectrum,the efficiency range of locusts′ phototactic response can be extended by reasonable combination of cosine alternating light and flash light.
		2011 Vol. 32 (3): 260-265 [Abstract] ( 1003 ) [HTML 1KB] [ PDF 2022KB] ( 1941 )

	266	Simulation of ESP control system based on seven degree freedoms vehicle model
		WANG Liangmo, AN Lihua, WU Zhilin, MA Chunhui, LI Li
		By magic formula, tire longitudinal force and lateral force mathematics models were built, and the mechanical properties at pure tire condition were completely expressed. Seven degree freedoms vehicle model with ESP control system was researched. By using simulation software of Matlab/Simulink, a vehicle dynamic model which contains elements of engine, brakes, tire model and vehicle body systems was established. The basic principles and control strategy of vehicle stability were theoretically designed by using fuzzy parameters of PID control method. According to ISO 3888, the vehicle handling simulation was conducted under double lane change and other limit driving conditions. The result shows when difference between yaw acceleration and nominal value yaw acceleration is over a certain range, the ESP control system brakes the controlled wheel, and limits the increase of sideslip angle. The vehicle lateral acceleration could be effectively controlled by steering wheel with good trajectory following and vehicle handling stability could be significantly improved. e
		2011 Vol. 32 (3): 266-271 [Abstract] ( 1904 ) [HTML 1KB] [ PDF 2275KB] ( 2747 )

	272	Direct torque control characteristic modeling of in-wheel motor
		YAN Fuwu, ZHANG Pei, DU Changqing
		Using inwheel motor as concrete study subject, the direct torque control (DTC) was proposed to overcome the disadvantages of slow torque response and poor dynamic performance for vector control. Based on the DTC mathematical model of asynchronous motor, inwheel motor DTC simulation model was established by Matlab／Simulink software. The dynamic performance of inwheel motor was analyzed through simulation model. Based on dSPACE, inwheel motor test stand was designed. A performance test for inwheel motor was conducted on the test stand. The simulation and test results show that the torque response of DTC is fast and torque ripple is large only at low speed. The simulation model is suitable to express the dynamic performance of inwheel motor well. The dynamic performance of DTC can meet the requirement of driving system
		2011 Vol. 32 (3): 272-276 [Abstract] ( 1661 ) [HTML 1KB] [ PDF 1539KB] ( 2162 )

	277	Numerical analysis of refueling emission of gasoline vehicle tank
		HE Ren, WEI Haiyan, LIANG Linlin, CUI Wenyan
		In order to control refueling emission of gasoline vehicle, the structural feature of tank for gasoline vehicle and the variation characteristics of interfacial area of mass transfer during refueling were analyzed. A new method for predicting refueling emission of gasoline vehicle with irregularshaped tank was presented. The explicit mathematic model of refueling emission, which bases on the timechangedependent diffuse principle of interfacial area of mass transfer and infinitesimal method, was established to suit for gasoline vehicle with irregularshaped tank. Take two different shape of automotive tanks for example, theoretic calculation and experiment results show that the refueling emission model which bases on interfacial area change of mass transfer can be used to predict refueling emission of gasoline vehicle with irregularshaped tank. Due to the interfacial area of mass transfer changes greatly,the diffusion velocity of gasoline vapor molecular is sped up, which leads to the increase of the molar average velocity and the amount of gasoline evaporation, and the refueling emission for gasoline vehicle with irregularshaped tank becomes larger. Compared to the prediction of refueling emission without considering tank shape, the method is more practical and effective.
		2011 Vol. 32 (3): 277-280 [Abstract] ( 1665 ) [HTML 1KB] [ PDF 1460KB] ( 2897 )

	281	Active vibration control and simulation of gear transmission system based on fuzzy algorithm
		LI Yinong, FAN Zhenhua, LI Guiyan, ZHANG Feng
		A three freedom degrees mathematical model of a pair of involute spur gear transmission system was built using the lumped mass method. An active control structure was applied to control the gear meshing point vibration which was caused by transmission error. Through piezoelectric stack actuator displacement, the shaft′s vibration was controlled, which led the gear transmission error and noise being controlled. Based on the Matlab／simulink, a fuzzy PD active controller and a fuzzy active controller for system′s vibration were designed. A complete gear transmission vibration control system was established and simulated. The simulation results show that both fuzzy controller and fuzzy PD controller can effectively suppress the system′s vibration. Fuzzy PD controller is better than pure fuzzy controller for the gear system. The research results prove that the control method and control strategy used in this paper is practical and feasible.
		2011 Vol. 32 (3): 281-286 [Abstract] ( 2055 ) [HTML 1KB] [ PDF 1955KB] ( 2507 )

	287	Investigation on fuel injection and performance of diesel engine fueled with Jatropha curcas oil
		LUO Fuqiang, GUO Jian, WANG Ziyu, LIANG Yu
		The cylinder pressure, the pressure in fuel injection pipe near pump, NOx and soot emissions of ZH1115 direct injection diesel engine fueled with pure Jatropha curcas oil were measured under different loads at the rated speed (2 200 r·min-1) and maximum torque speed (1 760 r·min-1) on engine test bench. Compared with engine which fueled with diesel fuel, the pressure in fuel injection pipe of engine which fueled with Jatropha curcas oil increases quicker with higher maximum pressure in fuel injection pipe and cylinder and with higher maximum cylinder pressure rising rate. Moreover， their corresponding phases appear ahead. As the load increases, the maximum cylinder pressure,the maximum cylinder pressure rising rate, NOx and soot emissions enhance obviously. NOx and soot emissions decrease markedly under middle and high loads.
		2011 Vol. 32 (3): 287-291 [Abstract] ( 1341 ) [HTML 1KB] [ PDF 1910KB] ( 1812 )

	292	Numerical solution for vibration behavior of automotive brake disc and pads
		MENG Xianjie, WU Guangqiang
		To reduce or eliminate brake groan, the vibration characteristics and influence factors of the system with brake disk and pads were investigated. Considering the stiffness and damping between brake disk and pads as well as the tangent and normal vibrations, a nonlinear dynamic model with six degree freedoms was established. The parameters from numerical analysis were substituted into Jaccobi matrix, and the eigenvalues were obtained by Matlab. System stability at the balance point was analyzed with the RouthHurwitz criterion. Effects of normal load to brake disk and initial velocity on system vibration characteristics were investigated with numerical method. The results show that the system with given parameters is unstable at balance point, and the tangent and normal vibrations tend to become weak or vanish when initial velocity of the brake disk increases.However，the vibrations increase when brake load increases.
		2011 Vol. 32 (3): 292-296 [Abstract] ( 2034 ) [HTML 1KB] [ PDF 2009KB] ( 2219 )

	297	Preparation and adsorption dynamics of aminated-hypercrosslinked polymeric adsorbent resins
		YUAN Xinhua, Tian-Zhiwei, Lei-Yan, Song-Haojie, Cao-Shunsheng
		Three types of aminatedhypercrosslinked polymeric adsorbents were successfully prepared. The static dynamics of adsorption for phenol and aniline onto adsorbents from aqueous solution were studied. Effects of temperature and initial concentration on the adsorption were also investigated. The results show that the adsorption of phenol is pushed by physical and chemical interaction, while the adsorption of aniline is mainly pushed by physical interaction. The specific surface area of adsorbent decreases with the increasing of amido content, leading to the block within the resin pore by amido and decreasing of diffusion rate constant. The correlation coefficient is over 0.98, which shows that both of Lagergren and Kannan-Sundaram models can illuminate the adsorption process very well. All regressing curves by Kannan-Sundaram model are not through origin of coordinates, which indicates that the adsorption rate is affected by diffusion inside particulate and diffusion of membrane.
		2011 Vol. 32 (3): 297-300 [Abstract] ( 1823 ) [HTML 1KB] [ PDF 1478KB] ( 1736 )

	301	Experiment and mechanism analysis on DBD decomposing O2/N2
		WANG Jun, CAI Yixi, ZHAO Weidong, LI Xiaohua, WANG Pan
		The lowtemperature plasma test system which based on dielectric barrier discharge(DBD) reactor was estabished， and its electrical parameters were measured by Q-V Lissajous figure. Experiments were carried out to study the effects of applied voltage peak (Vp), power and electric field on the volume fraction of ozone and nitrogen dioxide from the decomposing of N2/O2 mixture gas. The results show that Eg increases with the increase of Vp, while f has little effect on Eg. Covalent bonds of O2 and N2 are broken by high energy electron which produced from the lowtemperature plasma reactor，leading to the synthesis of ozone and nitrogen dioxide. The volume fractions of ozone and nitrogen dioxide increase to maximal value firstly, and then decrease with increase of Vp. The volume fractions of ozone and nitrogen dioxide increase with the increase of initial oxygen volume fraction in the N2/O2 mixture gas, especially for the increase of ozone volume fraction.
		2011 Vol. 32 (3): 301-304 [Abstract] ( 2664 ) [HTML 1KB] [ PDF 1541KB] ( 2525 )

	305	Crystallization behavior, crystal structure and thermal expansion property of ZrW2-xMoxO8
		LIU Qinqin, CHENG Xiaonong, YANG Juan, SUN Xiujuan, ZANG Chuanliang
		ZrW2-xMoxO8 powders were synthesized by coprecipitation method using zirconium oxynitrate, ammonium tungstate and ammonium molybdate as raw materials. The effects of W／Mo ratio on the crystallization behavior, crystal structure and thermal expansion property of ZrW2-xMoxO8 were studied by differential scanning calorimetry (TG-DSC) and Powder X-ray diffraction (XRD). The results show that Mo substitution does not influence the negative thermal expansion property of the resulted ZrW2-x-MoxO8 which was synthesized either via the reaction of oxides raw materials (x<0.5) at transition of its corresponding trigonal and monoclinic phase (x≥0.5). The lattice constant at room temperature and the synthesis temperature decrease with the decreasing of W／Mo ratio. At high temperature, ZrW2-xMoxO8 adopting β-ZrW2O8 structure transforms to trigonal phase which does not possess NTE property.
		2011 Vol. 32 (3): 305-309 [Abstract] ( 1383 ) [HTML 1KB] [ PDF 2585KB] ( 1954 )

	310	Practical effects of engineering device coupling catalyzed iron with hydrolysis and acidogenesis
		HU Jian, WANG Hongwu, YU Yiping, MA Luming, CAI Lan
		According to the characteristics of catalyzed iron technology and hydrolysis & acidogenesis process, the coupling system was established to improve the biodegradability of the wastewater. The advection coupled reactor was designed and applied to the actual renovation project of wastewater treatment plant in chemical industry park. After implementation of the actual renovation project, the influent and effluent water qualities were detected and the biodegradability of the wastewater was analyzed. The treatment efficiency of hydrolysis & acidogenesis/catalyzed iron-CAST system was compared with that of the pure CAST system. The results indicate that ρ(BOD5)/ρ(COD) is improved to above 0.35 with the pretreatment of hydrolysis & acidogenesis/catalyzed iron coupling technology. The average effluent COD, ammonia nitrogen and total phosphorus of hydrolysis & acidogenesis/catalyzed iron-CAST system are 91，17.2 and 2.39 mg·L-1 respectively, and the corresponding average removal rates increase respectively from 69%, 0 and 46% to 75%, 46% and 57%.
		2011 Vol. 32 (3): 310-313 [Abstract] ( 1306 ) [HTML 1KB] [ PDF 1472KB] ( 1841 )

	314	Analytical model of series semiconductor thermoelectric generators
		LIANG Gaowei, ZHOU Jiemin, HUANG Xuezhang, ZHANG Tao, XU Bing
		In order to precisely represent the output performance of series thermoelectric generators, based on thermodynamics theory, semiconductor thermoelectric theory and law of energy conservation, an analytical model of series thermoelectric generators was set up by theoretical analysis and calculation. Approximate expressions of voltage, current and output power of series thermoelectric generators were deduced by the analytical model. An experimental platform was built to verify the model, and the output performance of a series circuit including two thermoelectric generators, which worked at different hot source temperature and hot sink temperature, was tested. The results show that the output power is decreased by the contact effects. The matched load is equal to the total internal resistance of series circuit only when the thermal contact resistance is ignored. The results derived from model are basically consistent with experimental results, and the model is suitable for the performance researching and designing of thermoelectric generator.
		2011 Vol. 32 (3): 314-319 [Abstract] ( 1681 ) [HTML 1KB] [ PDF 1612KB] ( 2615 )

	320	Reliability analysis of sink node in industrial control WSN
		ZHANG Rongbiao, CHEN Ting, SHEN Zhuo, SHEN Min
		In order to ensure the reliability of wireless sensor network (WSN) applied in industrial control domain, regarding the retransmission mechanism of common soft fault, reliability functional model was established based on qualitative analysis by using spare parts number of sink node and retransmission times as characteristic quantities. Effects of spare parts number and retransmission times on the reliability were quantitatively analyzed. Quantitative relationships among retransmission times, communication time and energy consumption were built by Markov chains and probability analysis. The WSN in power system was taken as an example to seek solution for the reliability model of sink node. The results show that when the realtime of network transmission and node energy consumption meet the requirements of the power system, the reliability of sink node can reach over 99.9% with two spare parts and three retransmission time, even if the bit error rate is 0.2×10-3.
		2011 Vol. 32 (3): 320-324 [Abstract] ( 1750 ) [HTML 1KB] [ PDF 1363KB] ( 1852 )

	325	Classification of EEG sleep stage based on Bayesian relevance vector machine
		SHEN Yue, LIU Hui, XIE Hongbo, HE Weixing
		To overcome the disadvantages of complicated calculation and uncertain parameter selection of support vector machine(SVM), a new algorithm based on sparse Bayesian relevance vector machine (RVM) was proposed to classify electroencephalography (EEG) sleep stage. Inference and optimization of parameters of the binary classification RVM were given, and binary tree RVM multiclass model was established. According to the known sleep stage annotations by experts, sample entropy (SampEn) features of each sleep stage were extracted from the EEG sleep signals of eight healthy volunteers without any medication in MIT/BIH database. Then the sleep stage types were identified through multilay RVM pattern recognition classifier on binary tree categorization by training and testing samples of sleep and awake period. The results show that the maximal identification rate of RVM can reach 89.00%, which is better than that of the SVM (87.67%). The number of relevance vectors and test time of RVM are both less than those of SVM, which means that the RVM method is an effective tool for sleep stage classification with better classification accuracy and computation efficiency.
		2011 Vol. 32 (3): 325-329 [Abstract] ( 1788 ) [HTML 1KB] [ PDF 1531KB] ( 2636 )

	330	Design and finite element analysis of bearingless synchronous reluctance motor
		ZHU Huangqiu, LI Yuanfei
		According to the special design characteristics of bearingless synchronous reluctance motor including torque windings and susepension windings, a new dichotomy approach of traditional motor stator windings was proposed. Based on the generation principle of radial suspension force in bearingless synchronous reluctance motor, mathematical model of radial suspension force was deduced. The 0.5 kW bearingless synchronous reluctance prototype motor was designed by dichotomy approach with two pole-pair torque windings and one pole-pair radial suspension windings. The distribution of magnetic fields was simulated by ANSYS, and the relationship between radial suspension force and windings′ current was determined. Effects of magnetic saturation and size of air-gap on radial suspension force were also studied. The results show that the prototype motor′s rotor can be suspended with 2.7 A rated current of torque windings and radial suspension force windings, 0.35 mm motor air-gap and 200 N of rotor radial suspension force
		2011 Vol. 32 (3): 330-335 [Abstract] ( 1338 ) [HTML 1KB] [ PDF 1980KB] ( 2325 )

	336	Estimation of camera pose through manifold optimization
		PAN Shaosong, ZUO Hongfu
		To minimize accumulative error of orthogonal iteration in camera tracking, a novel approach based on manifold optimization was proposed to estimate camera pose. Collinear error model was exploited to reformulate pose estimation into minimization of a realvalued function over manifold, and then theorems of differential geometry were adopted for objective optimization. Optimization processes were composed of vector updating and retraction mapping. Zero tangent vector field was searched by Taylor Expansion of objective function in affine tangent space of manifold, and the points which are deviated from manifold were reflected onto mainfold by retraction mapping. The performance of pose estimation by proposed algorithm was compared with that by orthogonal iteration, and its application in augmented reality was given. The results show that the performance of algorithm proposed is better than that of the orthogonal iteration. When noise variance equals 1, the relative deviation of new algorithm with synthetical datum is 0.5% for rotation axis and 0.25% for rotation angle, respectively, which are only one fifth and a half of those for orthogonal iteration.
		2011 Vol. 32 (3): 336-340 [Abstract] ( 2070 ) [HTML 1KB] [ PDF 1634KB] ( 3186 )

	341	Bi-objective optimization of network min-cost and max-flow based on genetic algorithm
		SHE Xiangyang
		Aimed at the defect of transfering network min-cost and max-flow to single objective optimization, the bi-objective optimization model of network min-cost and max-flow was proposed, and multi-objective genetic algorithm was adopted. The flow values of remain branches were encoded and initialized by multiobjective genetic algorithm, and the flow values of tree branches were calculated by decoding and circuit matrix. Based on network min-cost and max-flow function, nodes capacity and branches capacity restrictions, the generalized bi-objective function were set up according to multi-objective optimization theory. The flow scheme codes were evaluated by the generalized bi-objective function and evolved by evolution arithmetic operators to obtain optimization mincost and max-flow schemes by iterative algorithm. Mine ventilation network was taken as example to conduct the test. The results show that the bi-objective genetic algorithm of network min-cost and maxflow is feasible and effective. The variable number is reduced in this algorithm and algorithm efficiency is improved.
		2011 Vol. 32 (3): 341-345 [Abstract] ( 2033 ) [HTML 1KB] [ PDF 2111KB] ( 3427 )

	346	Unilateral contact buckling of thinwalled steel skin sheet under loading
		DONG Jun, LIU Minghui, LIU Qingzhen, DAI Buyun
		In order to get the influence of inner material stiffness on buckling coefficient of steel skin sheet under unilateral contact, the bimodulus constraint model was adopted to simulate the constraint of inner materials. According to a novel disaplacement function, energy method was used to deduce the buckling coefficient of steel skin sheet by the principle of stationary potential energy. The results show that the buckling coefficient of Kcr is directly proportion to the logarithm of compressive stiffness coefficient of kr1. When kr1 tends to 0, Kcr approaches a constant value and increases with the increasing of adhesive stiffness coefficient kr2. When kr1 tends to ∞, Kcr also tends to be a constant value with remarkable influence by kr2. The result shows that an appropriate increase of adhesive stiffness can significantly increase the buckling coefficient of the steel skin sheet when the compression stiffness stays at a constant value.
		2011 Vol. 32 (3): 346-349 [Abstract] ( 1443 ) [HTML 1KB] [ PDF 1483KB] ( 1850 )

	350	Experiment for flexural behavior of HRB 500 rebar reinforced concrete beam under serviceability state
		LU Chunhua, JIN Weiliang, YAN Yongdong
		The flexural behavior of eight HRB500 rebar reinforced concrete beams was compared with that of two ordinary rebar reinforced beams basing on crack distribution, crack width and deflection. The results indicate that the flexural behavior and deflection mode of test beams with HRB500 rebar are basically consistent with those of ordinary rebar reinforced concrete beams. Under the serviceability limit state, average crack spacing and midspan deflection are equivalent to the calculation values according to formulas in GB 50010—2002. However, most of calculated shortterm maximum crack width are larger than measured values. According to the test results,the normal formula of crack width should be revised by decreasing guarantee radio for maximum crack width and modifying calculated stress of rebar.
		2011 Vol. 32 (3): 350-354 [Abstract] ( 2009 ) [HTML 1KB] [ PDF 1947KB] ( 2155 )

	355	Typical calculation methods of stress intensity factors and crack propagation criterions
		CHUN Qing
		Samples with center crack, single side crack and two sides crack were analyzed by FRANC2D to compare calculation methods for three stress intensity factors based on displacement correlation method, virtual crack closure integral method and J-integral method, and three crack propagation criterions of maximum circumferential stress, maximum strain energy and minimum strain energy density. The results show that calculation precision of J-integral method and virtual crack closure integral method are superior to displacement correlation method. Two types of calculation error of J-integral method and virtual crack closure integral method decrease with crack propagation, while that of displacement correlation method increases. Calculation velocity and precision of maximum circumferential stress criterion and minimum strain energy density criterion are prior to maximum strain energy release rate criterion. Calculation time and angle error of maximum strain energy release rate criterion is larger than that of other two criterions.
		2011 Vol. 32 (3): 355-358 [Abstract] ( 4067 ) [HTML 1KB] [ PDF 1758KB] ( 4444 )

	359	Experiment of tensile constitutive characteristics of concrete after freeze-thaw cycles
		CAO Dafu, FU Lizhi, QIN Xiaochuan, Yang Zhongwei
		In order to obtain tensile stressstrain curve and formula of rising part for concrete after freeze-thaw cycles, samples with four strength grades were subjected to uniaxial tensile experiment after 0, 25, 75, 100 or 125 freeze-thaw cycle times. Based on normal tensile stress-strain relationship, tensile stressstrain constitutive relationship of concrete after freezethaw cycles was proposed. The results show that the slope of the rising part of tensile stressstrain curve falls down gradually and the peaks of tensile stress and strain decrease linearly as cycle times of freeze-thaw increase. Samples with high strength grade express less decrease of peak tensile stress and strain than those with low strength grade for the same freezethaw cycles, while decreasing rate has slight difference. Key words:
		2011 Vol. 32 (3): 359-363 [Abstract] ( 1626 ) [HTML 1KB] [ PDF 2205KB] ( 1849 )

	364	Mechanics model for geometrical nonlinear problem of large curvature thin-walled curved girder
		CHEN Yujji, LUO Qizhi
		The shear lag warping displacement function of the cantilever, top and bottom plate of flange section were assumed. The total potential energy function of the structure was obtained by the assumption. Based on potential various principles, the geometrical nonlinear governing equation of the large curvature thinwalled curved girder was deduced with regarding of the influence of curvature radius change along beam width. The approximate solution was obtained by spline least squares collocation method to deduce the internal force and displacement of the structures under loads. Effect of curvature radius on the structure was also analyzed. The comparison of calculating value with test results illuminates that the proposed method is reliable, and especially that the important force locations of curved box girder cross-section are very close. The results show that the influence of curvature radius change along the beam width on shear lag could be ignored when the ratio of width and diameter is less than 0.1. The shear lag coefficient in each section tends to symmetry gradually with the increasing of the curvature radius， while the torsional angle and the deflection decrease with the increase of their linear elastic scopes in the relationship of torsional angle-load and deflection-load.
		2011 Vol. 32 (3): 364-368 [Abstract] ( 1217 ) [HTML 1KB] [ PDF 1603KB] ( 2646 )

	369	Strong law of large numbers for asymptotic circular second order Markov chains
		YANG Weiguo, TANG Ying
		The strong limit theorem of special nonhomogeneous Markov chains—asymptotic circular second order Markov chains was studied. Firstly, the definition of asymptotic circular second order Markov chains was introduced. Then according to the limit property of nonhomogeneous Markov chains ternary functions, the strong limit theorem of asymptotic circular second order Markov chains for states occurrence frequencies was established. Finally, the strong large numbers law of asymptotic circular second order Markov chains for states occurrence frequencies was obtained. The strong law of large numbers for second order nonhomogeneous Markov chains was extended as a corollary. The strong large numbers law for asymptotic circular second order Markov chains can be used for the source coding theory.
		2011 Vol. 32 (3): 369-372 [Abstract] ( 1473 ) [HTML 1KB] [ PDF 0KB] ( 555 )

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