Abstract:The paper presents a modification method for the recorded earthquake ground motions to match multi dimensional design input energy spectra with wavelet. According to the approximate relationships between input energy spectra and pseudo acceleration response spectra, the recorded earthquake ground motions are modified to match the target response spectra preliminarily by synthesizing wavelets in time domain. In this process, the non stationary intensity and frequency characteristics of real records have retained. Then the second cardinal B spline wavelet is used to simulate the multi dimensional accelerograms. By modifying the amplitudes of special wavelets of low fitting accuracy and the wavelets affecting peak values of velocity mostly, the target input energy spectra and peak ground values of velocity can be matched by iterations. The numerical example demonstrates this method is of high fitting precision with few changes to the original energy distribution, which is a new artificial ground motions’ generating method for dynamic analysis of structures designed by energy balance.

Abstract:A new approach is proposed for stochastic finite element method (SFEM) and reliability analysis by using a complex variable technique. The random factors in engineering are defined as complex variables, the first derivative formulation can be obtained by the Taylor’s series of a complex function. This derivative method is computationally very accurate, efficient, and very easily implemented. In SFEM, to get the variances of responses, it only needs to implement FEM in complex variables space, without a need of partial derivatives of FEM functions. In the iteration scheme of SFEM reliability analysis, the real parts of complex response is considered as the response value to simplify the process. The complex variable method greatly simplifies SFEM and reliability program, providing a feasible approach for engineering application.

Abstract:The fatigue lives of wires are mainly affected by live loads, especially traffic load. This paper studies the fatigue lives of wires on account of the traffic load effects on the fatigue crack growth and the critical crack length. First, the Paris Law is simplified for the analysis of crack growth, which shows that the mean value of stress range has great effects on the fatigue lives despite of the distribution function of the stress range. Then, based on the distribution of maximum traffic load from Rice equation, the traffic load effects on the critical crack length are analyzed and the failure probability of fatigue lives is proposed. The above approaches are applied to stayed cable wires of an actual bridge. It is found that the variability of stress range has little effect on the fatigue lives. And it can be drawn from the results that the maximum traffic load has some effects on the fatigue lives and the standard deviation of fatigue lives can be up to 9 weeks.

Abstract:To investigate the mechanical performance of the tunnel lining segments, a series of fire experiments on the reinforced concrete (RC) and the steel fiber reinforced concrete (SFRC) segments under different load cases were conducted. The HC curve was employed in the experiments. The results indicate that the internal force of the segments varies significantly, which is equal to a loading and unloading action on the segments and aggravate their damages. The initial load presents a great effect on the ultimate load of the segments after high temperature, and the greater the initial load, the smaller the ultimate load. Furthermore, the ultimate load of the RC segments is larger than the ones of the SFRC segments. The maximum temperature has lesser influence on the ultimate load of the SFRC segments under high temperature, while it exerts a significant effect on the RC segments. And the higher the maximum temperature, the smaller the ultimate load of the RC segments under high temperature.

Abstract:According to its own characteristics of long distance taken image with cracks on tunnel lining， a new identification and width measuring algorithm for tunnel lining crack was developed by combining the calibration curve of camera fitted with experimental data, on the basis of some image processing means, such as image enhancement pre processing, region extraction of crack with loop iteration method, mathematical morphological analysis, edge detection of crack with sub pixel method. Verified by laboratory tests, when the shooting distance is less than 8 m, the algorithm is of high precision and the measurement error of crack width is generally less than 0.40 mm. According to its application, the maximum error of this algorithm is 0.37mm, the minimum error is 0.08mm, the average error is 0.20mm which meets the requirements of engineering measurement.

Abstract:In soft ground with lower confined aquifer, the bottom of an excavation may appear hydraulic heave like erosion, piping, bottom heave and hydraulic uplift at high hydraulic gradient. Combined with deep and large excavation engineering immediately adjacent to a subway hub, centrifugal model test was designed to simulate hydraulic heave in high cohesive aquiclude, at different hydraulic loads. In addition, numerical model was established to analyze soil stress strain mechanism at the hydraulic loads of centrifugal model test. Centrifugal model test and numerical simulations results show that under the effect of confined water, aquiclude uplift large in the central of foundation pit while small around the retaining wall, and aquiclude deformation curvature increase when confined water level become higher; the soil shear strain is greater than volume strain in aquiclude adjacent to retaining wall, but volume strain is greater at interface between aquiclude and confined aquifer, which produces discrete crack and wedge failure, and also make the effective stress in the region becomes zero; the low permeability cohesive aquiclude appears hydraulic uplift under the combination of shear failure mechanism and interface wedge failure mechanism.

Abstract:A series of tests were carried out with the heat probe method by thermal properties analyzer to investigate the thermal conductivity of shanghai ⑤1 layer silty clay, the most common type in the metro tunnel engineering. The test results show that the thermal conductivity of saturated silty clay decreases with the void ratio. When the water contents drop down gradually from saturated value to dry value, the soil sample shrinks evidently first and then its thermal conductivity increases. While the water contents drop down near the plasticity limit, the volumetric shrinkage becomes stable and the thermal conductivity reaches its maximum value. After the peak, the thermal conductivity decreases with water contents. Finally, some existing empirical formulas were introduced to fit the test data, and their fitness was verified.

Abstract:The flexural stresses and tensile strains in asphalt pavement layers were studied. The hood face coefficient was proposed to characterize the influences of vertical compression stresses and shear stresses on the flexural stresses and tensile strains; the neutral axis moving coefficient was introduced to describe the differences between smooth contact and full friction contact in layers; the flexure torque distribution coefficient was put forward to show the influences of different bend curvature on asphalt layer and base. As to asphalt pavement with nonuniform modulus, the surface equivalent modulus was deduced by bending rigidity equivalent principle, and then the errors of the approximate calculation methods for the tensile strains at the bottom of surface and the flexural stresses at the bottom of base in asphalt pavement whit nonuniform modulus were discussed. Usually, the approximate calculation errors are less than 5%.

Abstract:When vehicles moving at a uniform speed on concrete pavements, the influences of different parameters, such as the vehicle parameters (concentrated mass, suspension stiffness and tyre stiffness), the pavement structure parameters (pavement thickness, joint width, joint faulting, joint load transfer capacity etc.) and the sub grade parameters (sub grade reaction modulus, sub grade damping and sub grade strength weakening index etc.), on the time varying force are systematically analyzed with the established quarter vehicle road coupling dynamics model and the direct integration method. The curves of loading impact factor (dynamic load upon static load) against a variety of parameters are provided, and the statistic characteristics of loading impact factor is also depicted. Then, the dynamic displacement and strain of concrete pavements are discussed accordingly. The results show that the variance of time varying force is getting larger with the increase of the vehicle moving speed, and the dynamic effects of displacements and strains on concrete pavements become more remarkable; therefore, while designing concrete pavements, the dynamic effects of concrete pavement arising from vehicle road interaction shall be considered.

Abstract:According to the field test data and theoretical calculation result, a standard based on high weight deflector (HWD) testing was established to identify void beneath airport cement concrete pavement. An analysis was made of the influence of all kinds of voids on loading stresses of airport cement concrete pavement with ABAQUS 3D FEM model, and an example was given to show the influence of void on pavement’s service life. The result shows that identification standard for void beneath slab edge is “slab edge deflection/slab center defection> 1.8”, and void identification standard for void beneath slab corner is “slab corner deflection/slab center defection> 3.0”. When the void beneath slab becomes prominent loading stresses of airport cement concrete pavement will increase by over 250%, and the pavement’s service life is shortened distinctly. The influence of the void area is not obvious on the early stage of void development, but it increases while the base response modulus of void region decreases.

Abstract:Micro surfacing is widely used as an effective technology of preventive maintenance. However, for high temperature and rainfall in Guangdong region, micro surfacing has many disadvantages, such as poor abrasion resistance and short life ,which seriously influence the application of preventive maintenance in Guangdong province. Therefore, this study developes a new type of micro surfacing technology—epoxy high performance micro surfacing. The core of the new type of micro surfacing is adding an appropriate proportion water based epoxy resin and waterborne epoxy curing agent in micro surfacing mixture.water based epoxy resin and waterborne epoxy curing agent have chemical reaction ,which form high performance bonding network structure of space. Indoor wet wheel wear test results show that anti wear and resistance to water damage of epoxy high performance micro surfacing improves about 60%, compared with conventional micro surfacing. Based on driving wheel pavement analyzer, the indoor accelerated test on epoxy high performance micro surfacing showes that the anti sliding and anti spalling performance of epoxy high performance micro surfacing is significantly superior to conventional micro surfacing.

Abstract:In order to appraise the performance evaluation about highway maintenance in objective and accurate way, a new index construction method based on business customer internal management clearning and growth (BCIL) index and key performance index was given. Combined with the performance evaluation project about highway maintenance of a highway management department in Shanghai, the index system of performance evaluation was established from four aspects such as operation, client, interior management, study and development with the proposed index construction method.

Abstract:A hydrogen based membrane biofilm reactor (MBfR) was applied for simultaneous biodegradation of selected oxidized contaminants in groundwater including nitrate (NO-3N), sulfate (SO2-4), bromate (BrO-3), chromate (Cr(Ⅵ)) and para chloronitrobenzene (pCNB). The autohydrogentrophic bacteria lived on the membrane surface bioreduced nitrate to N2, sulfate to sulfide (S2-/HM2S), bromate to bromide ion (Br-), Cr(Ⅵ) to Cr(Ⅲ) and pCNB to pCAN and AN with hydrogen as electron donor. Removal and/or toxicity decrease of these oxidized contaminates was achieved through biological reduction. After biofilm enrichment and 32 d continuous running, the reactor reached a steady state for removing oxidized contaminates with a nearly complete removal for nitrate and bromate, 19.8% for sulfate, 85.6% for chromate, and 86.1% for pCNB, under the hydrogen pressure at 0.06 MPa and hydraulic retention time at 4.67 h. The results show that the MBfR technology can be effective for removal of oxidized contaminates and of a potential application in the treatment of groundwater.

Abstract:This paper describes the general principles and research methods of delineating source water protection areas based on the two dimensional flow pollutant model. Taking Gong Lake as an example, the two dimensional flow pollutant model of Gong Lake was first built and run according to Delineating Source Water Protection Areas (HJ/T338—2007). The water transfer in Wangting hub was regarded as the main impact on water quality in Gong Lake, and the water quality indexes such as CODMn, TP and TN in different situations were analyzed in 2010. Then numerical simulation was used to delineate source water protection area on the basis of the two dimensional flow pollutant model and GIS method. The study results provide the technical support for delineating source water protection areas.

Abstract:A sampling survey investigated the formation of a nitrogenous disinfection by product trichloronitromethane (TCNM) from pre chlorination, and the reduction of TCNM concentrations by subsequent conventional water treatment processes, i.e. coagulation, sedimentation, and filtration, with different seasons. The level of the measured TCNM had little change with the seasons, and were closely correlated with the dissolved organic nitrogen (DON), suggesting that DON plays an essential role in the formation of TCNM. The conventional treatment filtration had a certain effect on the reduction of TCNM.

Abstract:The water quality survey was divided into four parts such as conventional physical and chemical indicators, organic matters, algaes and nutrients indicators. Water pollution index (WPI) was adopted to evaluate the water quality. The results show that indicator changes are all linked to the growth of algaes in water. Considering total nitrogen, water quality of site 5 is even up to Ⅴ inferior class, the reservoir as a whole for Ⅳ class; without total nitrogen, water quality of site 5 is above Ⅲ class, water quality of site 3 is above ⅡClass, the reservoir as a whole for Ⅱ class. The Qingcaosha reservoir as a drinking water source can fully meet water quality requirements.

Abstract:In order to study the problem of concrete carbonation on meso scale, a 3D spherical aggregate generation method based on the cumulative distribution function (CDF) is established. The influence of randomness in this method on the simulation results is analyzed. The principle of how to determine the parameters such as maximum diameters, minimum diameters and volume fraction of aggregate is discussed as well. Based on the previous method, a simplified numerical model of concrete carbonation is further proposed. The influence of aggregates on the concrete carbonation process on macro scale is analyzed. The results show that the dilute effect and tortuosity effect caused by aggregate can decrease the concrete carbonation depth. Besides, the nonuniform distribution of aggregates in cement paste will result in the inhomogeneity of concrete carbonation depth on macro scale.

Abstract:Based on the mechanical properties of each material phase in recycled aggregate concrete (RAC), a two dimensional modeled RAC was built, and the stress distribution characteristics of the modeled RAC under uniaxial compressive were obtained by meso level numerical analysis. A parametric analysis was conducted to investigate the sensitivity of the stress distribution of the modeled RAC, which focused on different mechanical parameters of natural aggregate, interfacial transition zone (ITZ) and old hardened mortar. Results show that a concentration of tensile stress and shear stress produces at new and old interfacial transition zones between the natural aggregates. The higher elastic modulus of natural aggregates are, the higher the magnitude of stress concentration is, and the higher elastic modulus of the interfacial transition are, the lower the magnitude of stress concentration is. Whereas the effects of the elastic modulus of old hardened mortar on stress concentration are not evident.

Abstract:The paper presents a new method about the granularity computation of reconfigurable machine tools based on quotient space theory for improving the response of quick structure configuration layout of manufacture system. Decomposition behavior of dynamic systematic structure is depicted by quotient space theory of the granularity intuitively and formally, which can meet different requirements through the transform of coarse granularity to fine granularity. The quotient space theory of the granularity is adopted to achieve quick granularity decomposition and combination physics implement of systematic structure model in system configuration layout, the creativity function decomposition and structure matching model is set up with the aid of the quotient space theory. It expresses granular correlative features of the configuration layout of reconfigurable machine tools roundly and corresponding correlative variety of aim assignment, and quick optimized decomposition technology of module of reconfigurable machine tools is realized. Finally, the method is verified by a case study.

Abstract:Control technique is an effective way to synchronize multi vibration hammer. For the problem of electromechanical coupling in the control of two vibration hammers, the dynamics equations of the vibrating system and mathematical model of electromechanical coupling were established. Then the simulation model of Matlab/Simulink was established, and the simulation results show that the self synchronous occurs only under certain conditions during electromechanical coupling. Synchronous control strategies and algorithms were studied in the condition of electromechanical coupling, a synchronization control mode named “virtual master + PID” was established. In the end, experiments verify the characteristics of electromechanical coupling and the synchronous control strategies as well as the algorithms, and the synchronization accuracy proves to be able to meet engineering application.

Abstract:An optimization method about layout of exhaust hangers location was presented by vibration transfer function(VTF). Mathematical model of the VTF from engine excitation to exhaust was established with finite element method by taking the layout of hangers location in a hybrid electric vehicle(HEV) as an example. Then summation of relative displacement response of points on the exhaust was calculated in range of vibration frequencies. Finally, an optimized layout was obtained on the basis of the minimum of the summation of relative displacement response. The results indicate that the hanger location is decided by engine excitation, modal participation factors and modal vectors of powertrain and exhaust together in the VTF method. It was proved that vibration accelerations of the exhaust and rail of seat in the optimization layout reduced by more than 17% in comparison with the initial one based on the test data of t he HEV. So the optimization method about layout of hangers location by the VTF can be resorted to hanger location design.

Abstract:An analysis was made of three models for proton exchange membrane fuel cell(PEMFC) such as the distributed parameter model, the lumped parameter model and the mixed parameter model in terms of their characteristics and application. A review was made on the recent development of the distributed parameter models from five aspects including the conservation equations and their related computing methods; the characteristics of some important parameters; the research range; the development of simulated region and model verification.

Abstract:Biodiesel fuel blends were used on a diesel car, and the effects of biodiesel on vehicle’s particle number and size emission characters were studied with an engine exhaust particle sizer (EEPS) at new European driving cycle (NEDC) test. A test was made without any engine modification on a pure petroleum diesel and a pure biodiesel as well as some blends of petroleum diesel biodiesel with the blend ratio of 5%, 10%, 20% or 50% respectively. The results show that the total concentration of particle number reduces little when the car is fueled with biodiesel. The number of accumulation mode particles decreases whereas the number of nucleation mode particles increases significantly with the increasing of the blend ratio of biodiesel. At the same time, the average diameter of particle matters decreases and the peak of particle number concentration shifts to small diameter particle side.

Abstract:The paper presents a new discrete time linear time invariant state space model which considers the state estimation with the network packet dropout. Based on this model, the robust state estimation problem is transformed into a vector optimization problem. To solve this problem fast and effectively, the vector optimization problem is transformed into a scalar quadratic programming problem by the scalarization method. And with the further work, the initial problem can finally be transformed to solve a l1 regularized least squares problem, which usually has a standard and fast solution. Associating with the Kalman filter updating procedure, the new algorithm which can be adapted to the condition with the network packet dropout is proposed. The simulation results show that the proposed algorithm is effective.

Abstract:In order to describe the supercapacitor’s external characteristic more correctly during working process, the classical equivalent circuit model of supercapacitor was developed into a time varying equivalent circuit model, and the parameters of the time varying equivalent circuit model were identified through the least square algorithm with finite memory. The classical and the time varying equivalent circuit models were simulated and compared with the same experimental data under the platform of Matlab/Simulink. The results show that the time varying equivalent circuit model is of higher accuracy and able to reflect the dynamic characteristic of supercapacitor more precisely.

Abstract:Based on samples of manufacturing enterprises of small and medium sized enterprises(SME) on board before 2007, the relationship was explored between economic value added(EVA) and equity property, ownership concentration and equity balance degree of enterprises in growth stage and mature stage. The empirical results of multiply linear regression model show that there is a negative correlation between the proportion of state owned shares and enterprises’ value; tradable shares rates have little effect on the enterprise’s value; it is more complex to determine the effect of the degree of ownership concentration and equity balance degree on enterprise’s value. But generally speaking, higher degree of ownership concentration in growth stage and higher degree of equity balance in maturity stage contribute positively to enterprise’s performance.

Abstract:In order to analyze patterns of carbon dioxide emission from houses, an empirical model is proposed for decomposition of factors which influences carbon emissions from post occupancy of houses based on the optimization and expandetion of Kaya equation, and the modification of logarithmic mean divisia index. The factors of consumption level, energy structure, energy consumption intensity, household size and population density are discussed from Chinese statistic data of building energy consumption from 1995 to 2008. The factors of accelerating the growth of carbon emissions, and restraining the carbon emissions, are presented as well as carbon emission tendency. Several feasible proposals to control carbon emission from houses are also discussed in the end.