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Journal of Jiangsu University(Natural Science Eidtion)

	2011 Vol.32 Issue.2 Published 2011-03-10

	Article

Article

	125	Rapid detection of chlorophyll content in corn leaves by using least squares-support vector machines and hyperspectral images
		PENG Yankun, HUANG Hui, WANG Wei, WU Jianhu, WANG Xiu
		For the rapid and non-destructive detection of chlorophyll content in corn leaves, representative corn leaves with different N levels were collected. 60 calibration samples and 16 validation samples were prepared. Hyperspectral images in the range of 400～1 100 nm were collected and relevant chlorophyll content was measured according to the National Standard. Standard normalized variation, 13 points smoothing, and first derivative were applied as pretreatment method. According to the correlation coefficient, the wave band of 470～760 nm was selected as analysis object. Least squaressupport vector machines were used to establish the model between the corn leaves′ chlorophyll content and the hyperspectral data.The optimal parameters of LS-SVM were obtained by application of gridsearch based on crossvalidation. The results of LS-SVM model indicate technical support for hyperspectral application in remote sensing, with correlation coefficient of 096 and calibration coefficient of 093, respectively.
		2011 Vol. 32 (2): 125-128 [Abstract] ( 1911 ) [HTML 1KB] [ PDF 1636KB] ( 2691 )

	129	Design and test of a novel piezoelectric grain mass flow sensor
		GAO Jianmin, LI Yangbo, HAO Leibin, ZHANG Gang, YU Lu
		To acquire the grain yield information real time, a novel piezoelectric grain mass flow sensor was invented. Processes of single grain impacts on different sensitive elements of sensors which were made of aluminum alloy, steel No.45, ceramic and PVC were simulated respectively in LS-DYNA platform to select right force sensitive element material. Based on the simulation result, aluminum alloy was selected as force sensitive element material. Meanwhile, this sensor′s natural vibration frequency was computed based on the finite element model. From the computing result it′s concluded that this sensor′s natural vibration frequency is different from the combine′s. Furthermore, the program of data acquisition and processing was developed in WINCE platform applying C++ programming language. This sensor′s calibration test shows that its linear relative coefficient is up to 0999 4. Both indoor and farm test results indicate that this sensor is of high precision and prospect for applications.
		2011 Vol. 32 (2): 129-133 [Abstract] ( 1398 ) [HTML 1KB] [ PDF 2238KB] ( 1989 )

	134	Measurement of chlorophyll content in cucumber leaves based on GA-ICA and hyper-spectral imaging technique
		SHI Jiyong, Zou Xiaobo, Zhao Jiewen, Yin iaoping
		Chlorophyll distribution in cucumber leaves was non-destructively and rapidly measured based on genetic algorithms (GA) combined with independent component analysis (ICA) by Hyper-spectral images technique. Spectrum was extracted from hyper-spectral images of cucumber leaves after preprocessing. Firstly GA was used to search for an optimum informative wavelength of chlorophyll, then ICA signals were computed to build multiple regression model (MLR). The results show that 280 wavelengths were selected by GA and MLR model which was obtained based on 8 ICA signals. MLR model performs well with prediction coefficients of 0.931 2 and root mean standard error of prediction (RMSEP) of 0.191 4. 8 ICA signals of every pixel in hyper-spectral images were computed and chlorophyll content of every pixel was obtained according to the MLR model. Finally, the chlorophyll distribution map was estimated. Overall results sufficiently demonstrate that the hyper-spectral imaging technique can be used to measure the chlorophyll concentration and to estimate the distribution of chlorophyll in cucumber leaf.
		2011 Vol. 32 (2): 134-139 [Abstract] ( 1591 ) [HTML 1KB] [ PDF 2442KB] ( 2116 )

	140	Moisture content detection in organic substrates based on characteristic wavelength in near infrared spectroscopy
		ZHU Yongli, LI Pingping, MAO Hanping, WU Yanyou
		For developing a method for rapid detection of moisture content in vinegar residue substrates, visible-near-infrared spectroscopy was used for collecting the spectral data of the representative samples. The moving average filter (MAF) and first derivative (FD) were selected as the spectra preprocessing method. In accordance with the change of determination coefficients, seven spectra sections were chosen for determining the characteristic wavelengths. Stepwise linear regression (SLR) method was applied to perform the calibration models for predicting the moisture content. The results indicated that the characteristic wavelength was at 1 844, 1 889, 1 544 and 1 735 nm, respectively. Based on these wavelengths, 5 linear regression models were performed by stepwise regression method. For comparing the predictive precision of these models, the correlationship between prediction moisture content and that obtained by ovendrying method was analyzed. It is confirmed that the multivariate equation with the characteristic wavelength 1 889, 1 544 and 1 735 nm had higher predictive precision with correlation coefficient 0.967 4 and root mean squared error of prediction (RMSEP) 0098 1. It is concluded that the visible-near-infrared spectroscopy with characteristic wavelength selecting is a useful method for rapid detection of organic substrate moisture content.
		2011 Vol. 32 (2): 140-143 [Abstract] ( 1563 ) [HTML 1KB] [ PDF 1484KB] ( 1841 )

	144	Tire curing optimization based on artificial intelligence technology
		WANG Guolin, SHI Bin, JI Xinsheng, WANG Chen, LIANG Chen
		In order to optimize the tire curing degree of uniformity, the curing FE models of radial tire 11.00R22.5 were built by ABAQUS and the temperature fields were analyzed. Based on this, the curing degrees of tire were calculated by Arrhenius Equation. With the help of orthogonal experimental design, neural network and genetic algorithm, a new optimization approach for determination of external steam temperature during tire vulcanization process was proposed. It was expected that the refined optimization technique would lead to good curing degree of uniformity and curing time. From the comparison between the initial results and optimized results, it finds that more uniform level of the optimized tire vulcanization has been reached and the performance of tire has been upgraded. At the same time, the production cycle decreases and the productivity increases due to the reduced tire vulcanization.
		2011 Vol. 32 (2): 144-147 [Abstract] ( 1984 ) [HTML 1KB] [ PDF 3071KB] ( 2481 )

	148	Thermal management method of Ni-MH batteries for hybrid electric vehicle
		HU Minghui, QIN Datong, YE Xin
		The temperature rise and distribution of Ni-MH battery pack during its charging and discharging were studied. Considering the larger initial charging current due to the battery temperature rise a phased constant current charging control strategy was proposed. By analyzing the theoretical temperature fields model, the cooling structure of the original battery pack was optimized, and a phased joint control of constant current charging strategy was proposed. Then, a simulation of the battery thermal management control method was conducted and a test bench was setup about the battery pack temperature fields in the computing environment of Matlab／Simulink and Fluent. The test results verifed the advantages of the battery thermal management control method that we proposed.
		2011 Vol. 32 (2): 148-152 [Abstract] ( 2249 ) [HTML 1KB] [ PDF 1932KB] ( 2742 )

	153	Flexible modeling and stiffness analysis of leaf spring based on improved medium plane method
		SUN Li, HE Ren, LIU Wenguang, CHEN Shian
		To solve the problems of establishing the leaf spring flexible model slowly and having large stiffness calculation error in ADAMS software, the modeling idea of improved medium plane method was proposed. All main springs were simplified as an equivalent medium plane spring. Considering the horse bolts constraint, the medium plane was divided into many equal strength line segments according to the similar thickness principle. These line segments were simulated by the Beam elements, then the elements parameters were set according to the true character of the leaf spring medium plane. Taking a leaf spring with gradually hanging stiffness as a example, the 3D model was built in CATIA software, then the correlating coordinate values were extracted to establish the flexible model in View module. In the PostProcessor module, the relation of load and deform of leaf spring was drawn, and the calculated stiffness values of the improved and original methods were compared with the experimental value. The result shows that the improved method spring simulation values are very close to the test values and the culculation speed is improved.
		2011 Vol. 32 (2): 153-156 [Abstract] ( 1919 ) [HTML 1KB] [ PDF 1700KB] ( 2434 )

	157	Application of PMSM vector control system in PHEV
		ZHANG Jingming, REN Dianbo, NIU Xiaojing, CUI Shumei
		In order to make fully use of the electric motor in the PHEV, PMSM mathematical model is established and vector transformation method is used to achieve current direct decoupling control in both torque component and excitation component. This method controls the torque of PMSM effectively, and makes AC motors comparable with DC motors. Two kinds of PMSM vector control mode that fits for HEV are proposed, and different driving speeds are compared. MATLAB／SIMULINK simulation model based on above analysis is established. The results show that the control system is fast in response, has little fluctuations in output parameters and high efficiency. The vehicle has good dynamic characteristics and high recovery rate of braking energy, and the fuel economy is improved.
		2011 Vol. 32 (2): 157-162 [Abstract] ( 2046 ) [HTML 1KB] [ PDF 2006KB] ( 2755 )

	163	Numerical simulation on temperature and stress fields of CLAM steel TIG weld
		LEI Yucheng, ZHU Qiang, YIN Sha, JU Xin
		ANSYS thermal-structural coupling technology, Parametric Design Language, life-death element technique, and double ellipsoid heat source were applied togegher in the numerical simulation of temperature and stress fields on single layer welding and the single-sided double layer welding of CLAM steel TIG weld joints. Without considering phase change and only considering the effects of residual stress field, the stress field based on temperature field data was calculated. The results of simulation with that of experiment were compared. The numerical results of residual stress distribution are almost consistent with the experimental ones. On middle section of the surface, longitudinal stress is tensile stress near the weld zone, reaches the maximum in the fusion area, and turn to compressive stress away from weld zone. The transverse stress is small tensile stress. Residual stress of single-sided doublelayer welding specimen is lower than that of single layer welding specimen.
		2011 Vol. 32 (2): 163-166 [Abstract] ( 1616 ) [HTML 1KB] [ PDF 1983KB] ( 2164 )

	167	Friction and wear behavior of thermoplastic polyimide reinforced with carbon fiber
		XU Ying, ZHOU Hua, CHENG Xianhua
		In order to improve carbon fiber surface activity and comprehensive properties of the carbon fiber reinforced polyimide(CF／PI), rare earth solution (RES) surface modification and air-oxidation methods were used to improve the interfacial adhesion of CF／PI composite. The tribological property of the PI composites reinforced by the carbon fibers treated with different loads, reciprocating sliding frequency and surface modification methods were comparatively investigated. Results show that surface mo-dification of CF can improve friction and wear behavior of CF／PI composite. Friction coefficient, wear untreated CF／PI composite and air-oxitation CF／PI composite significantly increase with the increase of load and sliding frequency under dry sliding condition. Rare earth elements acting as surface modifier of the carbon fibers can increase interfacial adhesion and toughness between carbon fibers and PI matrix, and can improve tribological performance of the composites. In the same test conditions, the friction and wear properties of the RES treated CF／PI composite are optimal.
		2011 Vol. 32 (2): 167-170 [Abstract] ( 1874 ) [HTML 1KB] [ PDF 1913KB] ( 2285 )

	171	Synthesis of 5-benzoylacenaphthene in presence of ionic liquid ［Emim］Cl-AlCl3
		LIU Hua, CHENG Xiaonong, YUAN Xinhua, LUO Ying, HUANG Lijing, CHEN Min
		To obtain new fine chemical and macromolecule intermediate, the Friedel-Craft acylation of acenaphthene with benzoyl chloride catalysed by ［Emim］Cl-AlCl3 ionic liquid to synthesize 5-benzoylacenaphthene was investigated and 5-benzoylacenaphthene was determined by GC／MS analysis. According to orthogonal experiments, the optimum technological conditions were obtained as follows:n(acenaphthene)∶n(benzoyl chloride)∶n(［Emim］Cl-AlCl3)=1∶2∶1, temperature 35 ℃ and time 45 min. The yield of 5-benzoylacenaphthene was 886％ under such conditions. Furthermore, the yield of 5-benzoylacenaphthene changed a little after the catalyst was reused for five times. Pure 5-benzoylacenaphthene was prepared by extraction and recrystaling and the structure of 5-benzoylacenaphthene was identified by measuration of melting point, GC／MS, FT-IR and 1H NMR analyses.
		2011 Vol. 32 (2): 171-174 [Abstract] ( 1296 ) [HTML 1KB] [ PDF 1249KB] ( 1846 )

	175	Constraint effect and fracture behaviour for X100 pipeline steel
		WANG Zhongxian, HUANG Jianye
		Constraint effect and fracture behaviour for X100 pipeline steel with axial crack were quantitatively studied by elasticplastic fracture theory combined with FEA. Considering the plastic effects, a parameter βQ was introduced on the basis of J-Q theory and the fracture criterion of J-βQ double parameters was established. The failure curve of X100 was fitted from the data of JR-Δa experiment. Failure pressures for pipelines with internal and external axial cracks were predicted separately. The results show that constraint effect of the external crack is little stronger than the internal crack, but it is opposited when a／δ≤018. For shallow cracks (a／δ≤0.40), crack tip fields are not very constrained and yield failure is most likely to occur as plastic deformation is larger, the failure pressure of pipeline corrosion criterion(PCORRC) is conservative. For deep cracks, strengthened constraint effect results in small plastic deformation and fracture failure will take place.
		2011 Vol. 32 (2): 175-178 [Abstract] ( 1710 ) [HTML 1KB] [ PDF 2209KB] ( 2249 )

	179	Spouting characteristics of mixture of straw and coal particle in conventional spouted bed
		LIU Weimin, GUO Chunmei, LIU Jun, WANG Liqun, ZHAO Jiewen
		To obtain spouting characteristics of mixture of straw and coal particle in conventional spouted bed (CSB) in cold state, pressure drop of the bed and circulating rate of the mixture were used to show spouting behavior. The pressure drop of the bed with superficial air velocity, the effects of various parameters, such as proportion of mixture, height of the mixture and jet diameter on the pressure drop and the circulating rate of the mixture with air flow rate were all studied. Uniform design experiments were done to get regression equations to explain spouting characteristics. The results show that the pressure drop of the bed with superficial air velocity corresponds to that of CSB, and the curves of pressure drop and circulating rate,which were obtained in conditions of 0～30％ straw in the mixture, 250～340 mm height of the mixture and 25~41 mm jet diameter, may be used to guide selecting spouting parameters. Three regression equations were obtained by SPSS. The dependent variables in these equations are circulating rate of the mixture, pressure drop of unit material height, and circulating rate of the mixture per effective power, respectively, and the independent variables are jet diameter, air flow rate and height of the mixture.
		2011 Vol. 32 (2): 179-184 [Abstract] ( 1648 ) [HTML 1KB] [ PDF 1657KB] ( 1583 )

	185	Impeller design criterion based on numerical simulation of stock pump flow field and its application
		ZHANG Qihua, LI Yuexian, LIN Jianzhong, WANG Canxing
		The model of fiberflow coupling and the solving procedures are presented. The method is applied to the numerical simulation of the fiber suspension through the stock pump impeller. The results show that, the fiber orientations change drastically in the vicinity of the inlet; near the concave wall region the orientations flip obviously; and along the midstreamline and the streamline close to the convex wall, the orientations become more stable. The extra stress is significant along the concave wall close to the inlet, and it becomes uniform in the middle region and the downstream region. The results are further extended to the design of the stock pump impeller. Four design criterions are obtained as follows: the large radius of curvature on the first one third part of the blade, the channel expansion angle criterion, the large wrap angle criterion, and the blade outlet angle criterion. These criterions are added into the existing optimization system based on hydraulic design criterions. A stock pump impeller design system is developed. Then a new stock pump impeller is designed and the tested pump efficiency is 6％ more than the original machine, and is 3％ more than the Chinese stock pump standard.
		2011 Vol. 32 (2): 185-189 [Abstract] ( 1482 ) [HTML 1KB] [ PDF 2757KB] ( 1959 )

	190	Geometrical effects on residual stress in TC4 titanium alloy subject to laser shock processing
		CHEN Ruifang, CHEN Yuxiao, HUA Yinqun
		In order to improve the fatigue strength of TC4, Nd:Glass pulse laser was used to treat the surface of infundibulate specimen Xray stress analyzer was adopted to test the residual stress distribution of shocked area, and the process of laser shock on different geometrical specimen with different ratio (η) between the diameter of specimen and laser spot were simulated by ANSYS. The results show that the simulation is in good agreement with experiments. The infundibulate specimen can be simplified to cylindrical specimen. Geometrical effects on residual stress mainly act on X direction and Z direction and almost no effects on Y direction. The different η′s mainly affect residual stress distribution along the indepth direction and the circumferential direction, but very few on longitudinal direction.
		2011 Vol. 32 (2): 190-194 [Abstract] ( 1642 ) [HTML 1KB] [ PDF 2318KB] ( 1716 )

	195	Sheet metal sizing method based on laser shock wave
		DING Hua, CAI Lan
		To address the deformation problem of sheet metal generated in assembly process, especially in large or super large pieces of the structure, based on analysis of the characteristics of the traditional sizing method, a new sizing method based on laser shock wave stress was proposed. The principle and the components of the system were described. The test system was built with NA: YAG laser device, and the aluminium sheet with thickness of 06 mm was corrected by the system successfully. The influences of the sizing factors were analyzed theoretically. The results show that the sheet resume straight from the state of depression after correction by laser shock, and flatness is less than 005 mm. The deformation of the sheetmetal increases with the depth and magnitude of residual stress. To achieve accurate sizing purpose, the deformation of sizing can be adjusted by controlling the laser power density.
		2011 Vol. 32 (2): 195-198 [Abstract] ( 1328 ) [HTML 1KB] [ PDF 2062KB] ( 1720 )

	199	Numerical simulation of influence of pulse width on temperature field generated by femtosecond laser
		LU Lizhong, SHI Yunfei, XU Chenguang, XU Guidong, WANG Jijun, XU Boqiang
		In order to study the influence of laser pulse width on the electron and lattice temperature fields and their equilibrium time, based on the twotemperature coupling theory, and by taking account of the spatial and temporal shape of the laser pulse, the numerical simulation of the temperature field of the metal surface irradiated by femtosecond pulse laser of Gaussian distribution was performed by using FEM. The twotemperature equations were given and the numerical model was established. The temperature fields of electron and lattice in metal materials were obtained. The results show that pulse width of femtosecond laser affects not only electron and lattice temperature rising speed and temperature maximum in one point but also spatial distribution of temperature field. The electronlattice coupling plays a major role in the equilibrium time when the pulse width is much lower than picosecond regime, while the laser pulse width plays a major role in the equilibrium time when the pulse width is close to picosecond regime. This study establishes a theoretical basis for stress and ultrasound fields in metal generated by femtosecond laser.
		2011 Vol. 32 (2): 199-204 [Abstract] ( 1408 ) [HTML 1KB] [ PDF 1730KB] ( 2565 )

	205	QoS model of space-based networks based on DiffServ
		ZHANG Dengyin, ZHANG Baofeng
		In order to ensure the QoS in space-based networks (SBN), a new SBN QoS model based on DiffServ, which was short for SBN-DiffServ, was proposed. The SBN-DiffServ was based on the existed terrestrial network QoS model designed to meet the SBN features, such as the layered architecture and the multisatellite selection scheme. By extending the differential services code point (DSCP) and perhope behaviour (PHB), traditional queue management and multisatellite access mechanism were integrated. The SBN-DiffServ has achieved a better bandwidth and latency constraints on SBN QoS assurance mechanism. Simulation was completed in NS2 environment. The results show that the model offers different bandwidth and delay guarantee for different priority services, which can be used to ensure a good bandwidth and latency performance of SBN QoS assurance system.
		2011 Vol. 32 (2): 205-210 [Abstract] ( 1263 ) [HTML 1KB] [ PDF 1778KB] ( 2438 )

	211	An energy-efficient data dissemination method based on radius-ring scheme in sensor networks
		LIN Lin, YAN Shu, WANG Liangmin, JIANG Zhongqiu, NIAN Yi
		In order to solve the problem of hotspots of energy consumption by some sensor nodes during data dissemination, an energy-efficient data dissemination approach based on radius-ring scheme (RRS) was proposed. Sensed data was stored in the nodes located in radius. The message of query request inquired by mobile sink was matched in the nodes located in query ring. Sensed data would be sent to the mobile sink if the result of matching was true, or the message was continued forwarding. Firstly the data dissemination model in sensor networks was introduced. Then the selection algorithms of data forwarding for storage and query were given, and the data matching process was defined in detail. To verify the validity of the method, performance analysis and simulation comparison were performed with existing data dissemination schemes in aspects of query success ratio, node death time and energy cost. The results show that the proposed method can maintain a high success rate of queries, and network lifetime is greatly prolonged via balancing the energy consumption of sensor nodes with data propagating.
		2011 Vol. 32 (2): 211-216 [Abstract] ( 1253 ) [HTML 1KB] [ PDF 1382KB] ( 1481 )

	217	Collaborative modeling and simulation of Agent-DEVSbased on HLA
		CAO Qi, HE Zhongshi, YU Lei
		In order to extend the DEVS with abilities of intelligent modeling and distributed simulation, a collaborative modeling and simulation method for Agent-DEVS based on HLA was studied. The formal description of Agent-DEVS federate models based on Parallel-DEVS was proposed. The models ports in AgentDEVS were translated into data objects in HLA and the structure of the models was given. The communication mechanism was analyzed. The mapping between knowledge update in Agent-DEVS and attribute update in HLA, and that between models coupling in Agent-DEVS and instances interaction in HLA, were established respectively. Finally, the modeling and simulation application for material supply in emergent disaster was put forward. The results show that the reusability of Agent-DEVS models is enhanced by HLA and the interoperability of the models is enriched by knowledge update mechanism. In addition, the autonomy and independent ability for transaction processing are improved significantly.
		2011 Vol. 32 (2): 217-222 [Abstract] ( 1413 ) [HTML 1KB] [ PDF 2222KB] ( 2402 )

	223	particulate in four cities of Shanxi
		PENG Lin, CUI Hao, ZHANG Jianqiang, REN Zhaofang, MOU Ling
		The concentration of organic carbon (OC), elementary carbon (EC) and isotopic composition of total carbon (TC) in airborne particulate and pollution sources were studied which were sampled in Taiyuan, Jincheng, Changzhi and Lucheng city of Shanxi province. By analyzing the velative data of OC/EC and comparing the carbon isotopic composition of TC in airborne particulate and pollution sources, the sources of carbon in airborne particulate in the four cities were discussed. The coal-combustion dust, vehicle exhaust dust, soil dust, urban raised dust and airborne particulate in different functional sites in the four cities were collected in the heating and non-heating period. After pre-treatment, the samples were analyzed by thermal optical carbon analyzer, NC-2500 elemental analyzer and isotope mass spectrometry. The analyzing results of airborne particle and emission sources indicate that the TC of ambient samples in heating period is mainly from coalcombustion dust, while in non-heating period it is mainly from urban dust; coalcombustion dust and vehicle exhaust dust are the main emission sources of TC, and urban dust also has some contribution.
		2011 Vol. 32 (2): 223-226 [Abstract] ( 2069 ) [HTML 1KB] [ PDF 1315KB] ( 2067 )

	227	Electrocatalysis reductive degradation of DDT using manganese porphyrins
		ZHU Weihua, SHEN Wei, FANG Yuanyuan, ZHANG Ying, OU ZhongPing
		The catalytic properties of octaethylporphyrin and tetraphenylporphyrin manganese complexes on degradation of DDT were examined by cyclic voltammetry and UV-visible spectroelectrochemistry in DMF. No catalytic reaction was observed for DDT by neutral and first reduced manganese porphyrins, but both doubly and triply reduced complexes can catalyze the degradation of DDT. The electroreductive de-gradation of DDT was performed by using a technique of controlledpotential electrolysis and manganese porphyrins as the electrocatalysts. The products of DDT degradation were analyzed and characterized by the GC-MS technique. The main products of DDT degradation are DDD (1,1-bis(4-chlorophenyl)-2,2-dichloroethane), DDE (1,1-bis(4-chlorophenyl)-2,2-dichloroethylene) and DDMU (1,1-bis(4-chlorophenyl)-2-chloroethylene) under the given experimental conditions. Based on the experimental results, a mechanism for reductive degradation of DDT catalyzed by manganese porphyrins was proposed.
		2011 Vol. 32 (2): 227-231 [Abstract] ( 1468 ) [HTML 1KB] [ PDF 1562KB] ( 2190 )

	232	Prediction on compressibility coefficient of soil based on RBF neural network
		JIANG JianPing, YAN ChangHong, GAO GuangYun
		The neural network structure adopted is that, the node number of input layer of 4, the node number of hidden layer of 29, and the node number of output layer of 1 in the neural network structure are adopted. During the training of RBF neural network, the clustering method of K-means is used. The training speed of 0.15, the seed number of weighting of 2, the sigma parameter of 0.1, the weighting of 0.2, the maximum of iteration time of 16 000, and the average value of controlled of error 0.01 are adopted. It is found that the relative error of fitting value of compressibility coefficient compared with the observed value for 30 groups of independent variables in training RBF neural network model is between -2.540 0％～2.600 0％, and there are 25 groups of data whose relative error is 0, the absolute value of the relative error is 0.185 14％: In general,the error(<25％) is feasible in geotechnical engineering, so the prediction model of coefficient of compressibility with RBF neural network is feasible.
		2011 Vol. 32 (2): 232-235 [Abstract] ( 1660 ) [HTML 1KB] [ PDF 1360KB] ( 1585 )

	236	Influence of temperature history on crack resistance of early age concrete
		DING Jiantong, CHEN Bo, CAI Yuebo, SUN Wei
		The complex crack resistance of dam concretes cured by three modes, i.e. adiabatic curing, temperature matched curing (TMC) and 20 ℃ constant temperature curing, were studied through the temperature stress testing machine. Based on the maturity of concrete under adiabatic mode, the start time of cooling and cooling rate (i.e. 0.5~1.0 ℃/h) of other two curing modes were determined. Two kinds of aggregates combination were used in the tested dam concretes. Different to the test results of concretes under the curing modes of constant temperature and TMC, the tensile stress of concrete develops faster and the cracking temperature of concrete is higher under the adiabatic curing mode. Meanwhile, the crack resistance of concrete can be easily distinguished and evaluated under the adiabatic curing mode than under other two curing modes. However, the beginning point of cooling is overestimated and the crack resistance of concrete is underestimated under the adiabatic curing mode. Moreover, the influence of precompressive stress on the crack resistance of concrete cured under the constant temperature can not be obviously evaluated, and the cracking temperature of concrete is lower than true value under this curing condition. The test results show that the influence of the temperature history on the stress development and crack resistance of concrete could be reasonably investigated only under TMC condition.
		2011 Vol. 32 (2): 236-240 [Abstract] ( 1374 ) [HTML 1KB] [ PDF 1327KB] ( 1913 )

	241	Global exponential stability of a financial system with impulses and time-delayed feedbacks
		YAO Hongxing, PAN Hong, QI Li-Li
		As to a financial system with time-delayed feedback and impulses, the global exponential stability of the system was considered. By eliminating the influence of the length of time delay, a new criteria on global exponential stability of nonlinear differential system was established. The conditions of feedback strength and impulsive interval were worked out in order to stabilize the financial impulsive delay system. Finally, numerical simulations were presented to verify the theoretical results. It is concluded that impulses and timedelayed feedbacks can control the stability of system effectively.
		2011 Vol. 32 (2): 241-244 [Abstract] ( 1360 ) [HTML 1KB] [ PDF 1650KB] ( 1883 )

	245	Harmonic structure and effective resistance on a fractal interpolation curve
		FENG Zhigang, ZHANG Beibei
		In order to study the problem of harmonic analysis on fractal interpolation curve, its self-similar structure was considered according to the characteristics from creating curve. A sequence of resistance networks on a self-affine fractal interpolation curve was established by the construction of similar Laplacian on boundary points, and through limiting the Laplacian of network the corresponding harmonic structure was given. The results indicate that scale factor qualified some conditions and a symmetrical matrix form the fractal harmonic structure. At the same time, from the electrical point of view, the concept of effective resistance associated with the Laplacian between any two points was defined. This effective resistance is a metric on boundary points thus there′s a new metric space on this interpolation curve.
		2011 Vol. 32 (2): 245-248 [Abstract] ( 1333 ) [HTML 1KB] [ PDF 1173KB] ( 1683 )

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