Abstract:By considering the strain rate effect of concrete induced by the pore water, a mesoscopic rate dependent damage model was developed based on a compound system made up of a series of elastic elements and viscous elements. Then by introducing the developed rate dependent damage model to describe the damage evolution, the stochastic damage model was proposed to model the nonlinear behaviors of concrete under monotonic and hysteretic uniaxial loading. Based on the experimental data, the proposed stochastic damage model of concrete was systematically verified. The simulation results indicate that the typical nonlinear behaviors of concrete, including the softening, the residual strain and the rate dependency, can be well described by the proposed model. The developed model offeres a good choice for the nonlinear simulation of concrete structures.

Abstract:The formula of shaking table actuator hybrid test STAHT with Chang Method is deduced firstly and the numerical simulation platform based on Chang Method is established using software MATLAB. As errors are inevitable in STAHTs, the effects of errors on the stability and accuracy of STAHT with Chang Method are discussed with theoretical method and the numerical simulation platform is used to verify the theoretical results.

Abstract:An experimental study was conducted on four prestressed concrete continuous beams with unbonded tendons over entire loading. Support reactions and degree of moment redistribution at critical sections were analyzed. By secondary moment definition in post elastic range, total moment of a continuous beam in nonlinear stage could be decomposed into secondary moment and moment due to external forces, the variation of which over entire loading was studied. Based on revising the initial secondary moment and elastic external load moment separately, a redistributed moment formula for prestressed concrete continuous beams with unbonded tendons at the ultimate limit state were proposed. This formula was verified using a group of test specimens from literature. Results show that, the reason of moment redistribution in prestressed concrete continuous beams with unbonded tendons can be attributed to the stress increase of unbonded tendons and secant stiffness comparison charge between each part of the continuous beam. At the ultimate limit state, the higher global reinforcement indices at the section over inner support, the higher secondary moment reduction factor and the lower external load moment modulation factor. In the prestressed concrete continuous beams with unbonded tendons, the calculated moment of the section over inner support by the proposed formula is closest to the test results than the existing formulas. The proposed formula can provide a reference for the development of design code in relevant provisions.

Abstract:Centrifugal tests of reinforced soil retaining wall (RSW) with flexible/rigid facings and single flexible facing on the same soft foundation soils were carried out and their working behaviors under uniform loading on top of the walls were compared. The test results show: under the self weight and surcharge loading, for the wall with flexible/rigid facings, the rigid facing remains basically vertical and the maximum foundation settlement is below the embedded anchors; whereas for the wall with flexible facing, the facing tilts forward and the maximum foundation settlement is below the wall toe; during working stage, the lateral displacement of the face and the settlement at the surface of the wall with flexible/rigid facings decrease by approximately 50% as compared to the wall with flexible facing. And the differential settlement at the surface of the former wall is much less than that of the later one; the reinforcement forces and strain of the wall with flexible/rigid facings decrease because the embedded anchors bear the lateral earth pressures acting on the rigid facing; the rigid facing at the middle height bears tensile force at the outside and the maximum bending moment; whereas, the rigid facing nearby its bottom and top bears tensile force at the inside and relatively low bending moment; the wall with flexible/rigid facings can adapt large deformation and differential settlement of the soft foundation and can undertake more working stress on the top of the wall.

Abstract:A spatial prestressed concrete embedded slip model, into which the non thickness bond element simulating the interface of prestressed tendon and concrete was embedded via virtual nodes introduced on intersection points of the two, was proposed. Based upon displacement based finite element framework, a finite element equilibrium equation for the slip model was deduced according to virtual work principle, and a related calculation program was developed. The proposed model allowed prestressed tendon to go through concrete in any pattern, without consideration of its layout and direction and therefore with convenience in finite element mesh. The freedoms of virtual nodes could be reduced in the formation of the equilibrium equation. Verified by a numerical example of simply supported prestressed concrete beam with rectangular section, the proposed model was proved to be correct in elastic calculation and could be further used to develop a three dimensional nonlinear finite element analyzing program.

Abstract:According to the chloride induced reinforcing steel corrosion mechanism, the service life of reinforced concrete (RC) pipe piles can be divided into two phases, i.e., the corrosion initiation phase and the crack propagation phase. Based on Fick’s second law and Faraday’s law, the governing equation of chloride diffusion into RC pipe pile was established and a chloride induced reinforcement corrosion model in RC pipe pile was developed. The corrosion initiation phase time and crack propagation phase time were predicted by determining the critical chloride concentration and the critical attack penetration depth, respectively. Then the effect of surface chloride ion concentration, diffusion coefficient, cover thickness, reinforcement diameter, volume expansive ratio and the ratio of tensile strength to elastic modulus on service life of RC pipe piles was further analyzed, respectively. The analysis results indicate that the service life of RC pipe pile decreases with the increasing of surface chloride ion concentration, diffusion coefficient, reinforcement diameter and volume expansive ratio, while the service life of RC pipe pile increases with the increasing of cover thickness and the ratio of tensile strength to elastic modulus.

Abstract:Based on the limit equilibrium theory and the hypothesis of planar sliding plane, formulae were deduced to calculate open caisson earth pressure and frictional resistance during sinking on single non cohesive soils. Then the formulae were extended to layered cohesive soils by the methods of equivalent internal friction angle and self weight stress. The calculations were also compared with the measured data of a project. The results show that the earth pressure and frictional resistance decrease while internal friction angle increases, and increase while external friction angle increases. Sliding plane angle increases while external friction angle increases, decreases initially and then increases while internal friction angle increases. The theoretically deduced earth pressure between active earth pressure and earth pressure at rest is close to the measured earth pressure. In the actual projects, side wall frictional resistance can be considered unchanged below the depth of 12 m.

Abstract:The building roof snowmelt model, which was based on the previous mass and energy balance models, was adopted to compute the sliding snow loads on roofs in several typical countries. A simplified calculation formula that could compute the coefficient of sliding snow load was given. And a comparative study was made between the results from the simplified calculation formula and those from the load codes of some countries.

Abstract:A 3D numerical model of sediment transport and bed evolution of Caofeidian sea area under the combined forces of tidal current and wave was established based on Delft3D. This model was validated with the field measured tidal flow and sediment concentration in 2012. The validated model was used to simulate flow and sediment concentration fields and morphology evolution under the scenario of 2012. The responses of sediment transport and bed evolution were analyzed. The results show that: the sediment concentration in Caofeidian sea area is low, normally less than 0.2kg·m-3, its horizontal distribution presents higher in the west than in the east, and also in the nearshore and shoal areas than in the offshore area, while vertically increases from the surface to the bottom generally; the main erosions occur around Caofedian foreland, nearshore and shoals in the west and Dongkengtuo, the severe sedimentations appear in the western deep channels and Laolonggou creek. In general, the annual bed evolution is less than 0.5m and the morphology is stable with acceptable erosion and sedimentation rates.

Abstract:A rolling horizon optimization based three stage fuzzy controller for urban traffic signals is presented. This controller introduces overlap phases of conflict free approach flows to develop the model of a three stage fuzzy controller. Aiming at online learning of the parameters of fuzzy membership functions and fuzzy rules, a rolling horizon framework is used to efficiently explore the effectiveness of fuzzy controllers under different traffic conditions. In this framework, according to the real time observed traffic data, a genetic algorithm (GA) based heuristic integrated with golden ratio (GRGA) has been employed to yield reliable solutions. Experiments are conducted on a typical blackspot isolated intersection via Paramics based online simulation under daily and abnormal traffic scenarios. Extensive simulation results demonstrate the potential of the developed controllers for adaptive traffic signal control with rapid response to the uncertainty of time variant traffic flow at intersections.

Abstract:A research was made of the heavy vehicle traffic in port area to investigate its traffic characteristics. Based on the theoretical analysis and simulation, the type of traffic organization, Type C, was recommended for the access when the traffic volume of main roads is over 400 veh·h-1 or the left turn volume of minor road more than 250 veh·h-1. In addition, a theoretical calculation method of separation distance was also proposed, which was verified by a VISSIM simulation model for its safety and efficiency.

Abstract:To grasp the characteristics of bicycle as an egress mode of urban mass transit and give a quantitative description of transfer rule of potential bicycle share on the egress journey, 570 stations in Tokyo were chosen to be analyzed. The relationship was revealed among the bicycle share on access/egress journey in different zones and station density as well as infrastructure. Investigation of egress distance, walk and bus egress time and fare between 30 couples of stations and transport zones shows that time difference between walk and bus on egress journey and the ratio of riding time to total bus egress time have an influence on transfer of potential bicycle share on the egress journey. Transfer model of potential bicycle share on the egress journey in urban mass transit was established by multiple nonlinear fitting survey data to identify the impact of these two factors quantitatively.

Abstract:Based on elastic layer theory, horizontal distributions of tensile stress and subgrade compressive stress of pavement structure layer are studied. The rules of the radial stress coefficient φr and tangential stress coefficient φθ at the bottom of pavement structure layer and stress coefficient on the top of subgrade φz decreasing with the increasing of the horizontal distance between the midpoint of load and the calculation point r are investigated in detail. The influence of pavement structure parameters on the three stress coefficients φi is analyzed. The regression relationship among the three stress coefficients φi, pavement structure parameters and the horizontal distance between the midpoint of load and the calculation point r is given. The research results can provide foundation for the studying of multi axle load superposition effect.

Abstract:We quantified the concentrations of three chloroacetamides (CAcAms) in the final water of five drinking water treatment plants that use either chlorination or chloramination for disinfection and also we evaluated their toxicity in normal rat kidney cells using four in vitro toxicity assays, including cell viability test, single cell gel electrophoresis assay, apoptosis assay, and cell cycle analysis. An overall toxicity calculation suggests that minochloroacetamide (MCAcAm) represents a significantly higher cytotoxic and genotoxic risk than dichloroacetamide (DCAcAm) and trichloroacetamide (TCAcAm), albeit MCAcAm concentration was relatively lower than them. Moreover, the toxicity associated with CAcAms was higher in chloraminated waters than that in chlorinated waters due to the higher concentration of CAcAms in chloraminated waters.

Abstract:Sewage sludge was treated in a hydrothermal reactor within temperature of 170~270 ℃ to investigate the influence of hydrothermal temperature on heavy metals’ distribution and their leaching from solid products. The balance of heavy metals was calculated; and the influence of oxygen presence in the hydrothermal process was checked. Experimental results show that after hydrothermal treatment, heavy metals remain mainly in the solid products (hydrothermal chars) with small part moving into liquids. Leaching tests of hydrothermal chars were carried out according to two Chinese standards and the results showed that heavy metals in the hydrothermal chars were relatively stable, and that for sanitary landfilling hydrothermal chars were safer than the dried sludge; but for land application purpose, proper reaction temperature should be chosen to produce chars to replace sludge itself; as chars obtained at temperatures lower than 210 ℃ were inferior to sludge itself in respect to heavy metal leaching. Generally leaching of heavy metals from hydrothermal chars decreased as the hydrothermal temperature increased. From point view of heavy metals’ stabilization, temperature of 260 ℃ corresponded to the char with the least heavy metal leaching and to the liquid with the lowest heavy metal concentrations. Therefore, 260 ℃ was the best choice of hydrothermal temperature for the tested sewage sludge. Two digestion methods were adopted to digest hydrothermal chars for their heavy metals measurement. It was found that heavy metals in the chars obtained at temperatures over 210 ℃ existed mainly in residual species, which were quite stable. Also it was difficult for the heavy metals such as Zn, As, Pb and Cu to move from solid phase into liquid phase in the hydrothermal process. The appearance of O2 in the hydrothermal process slightly enhanced the mobility of heavy metals to the liquid phase, while heavy metals left in the chars were still stable.

Abstract:The process costing genetic algorithm combining with the constraint operator of inner space based on vehicle ergonomics is used to optimize the aerodynamic performance of car body. Three dimensional optimizational car bodies without wheels satisfying constraints of inner space with different structures and sizes are obtained. The coefficients of aerodynamic drag (CD) of those optimized car bodies are within the confines of 0.070 to 0.090, and their aerodynamic performances are all good. Under the constraints of inner space which comprises long fore capsule, big crew capsule and high rear capsule, a cheese head optimized car body whose CD is 0.0728 and a socket head optimized car body whose CD is 0.0860 are obtained. When the size of inner space constraint is smaller and the structure is simpler, the aerodynamic optimization result is better. When the style of the car body is more complex, the constraint of inner space makes a greater difference to the aerodynamic optimization results.

Abstract:A novel active transmission for parallel hybrid vehicle use was developed, which was based on the fixed axis gear and integrated the driving motor. Through automatic switch actuator, the motor could connect to the input or output shaft selectively. The former assured that, it could work efficiently by using gear ratios properly. During gear shift, it could supply wheels with driving force continuously by temporarily connecting to the output shaft. Dynamic property matching design of Electrified Manual Transmission(EMT) was accomplished. Through simulation, the way, how EMT realized gear shift process without power interrupt, was explained. Based on the development of the first prototype and test bench experiment, the ability of motor to maintain driving force uninterrupted during gear shift process was analyzed.

Abstract:For the purpose of brake pedal feel analysis, the dynamic model of vacuum booster brake master cylinder system was established including the key structure components, gas and liquid. Many factors such as structure clearances, spring pre load, friction forces, reaction disc stiffness, the change of gas mass flow rate and brake fluid bulk modulus were taken into consideration in the model. Without vacuum assist, the experiments of vacuum booster and brake master cylinder were carried out respectively by using brake fluid or not, and the key parameters of the model were identified. Then, the simulation of vacuum booster brake master cylinder system performance was carried out. The simulation results in the stage of on brake were shown in 3 quadrants figure formed by the vacuum booster pushrod force stroke curve, the master cylinder stroke curve and the master cylinder pushrod force curve. A comparative analysis with experiment results verified the brake master cylinder dynamic model, vacuum booster mechanical system dynamic model, and vacuum booster brake master cylinder system model.

Abstract:According to the practice that involute spur gears often work under the mixed elastohydrodynamic lubrication, a theoretical model of dynamic friction coefficient under mixed elastohydrodynamic lubrication was established based on the analysis on forces from meshing surfaces, which was a combination of elastohydrodynamic lubrication and boundary lubrication friction coefficients. A math model of sliding and rolling friction power loss was established with a variable of pressure angle, which erased the principle error of the prevailing power loss integral calculation. Finally, the simulation of power loss model was employed and compared with the test value, which verified the feasibility of meshing efficiency model of involute spur gear under the mixed lubrication.

Abstract:Three types of optimal perforated fin were chosen based on an analysis of orthogonal test and numerical simulation combination method, as the plain fin for based case, the four types of fin were employed on fin tube heat exchangers. The optimization of fin perforated parameters including three factors: the hole shape, the hole geometry dimension and the location. By wind tunnel experiments, it was demonstrated that elliptic perforated fin tube refrigerated heat exchangers had the best heat exchange ability with 1.5~5.2 m·s-1 air velocity under frosting conditions among the four types heat exchanger. When the air velocity was 2.5 m·s-1, the results illustrated that SK E B type elliptic perforated fin tube exchangers could increase refrigeration capacity per unit area, average fin surface heat transfer coefficient, compressor’s coefficient of performance by 37.8%,79.4%,25.0% respectively, while mean air flow resistance through the SK E B fin tube decreased by 30.0%.

Abstract:The study systematically analyzes the application of re manufacture on the stamping and welding type torque converter based on the technical process. Through the definition of the torque converter failure mode， separation of the reused parts, the reuse rate is defined. A fatigue test validates the reliability of the re manufaiture parts, which is meaningful to the widespreading and standardizaton of the re manufacture engineering for torque converter.

Abstract:Let H2(Ω,φ) be the Bergman space with respect to φ on the domain Ω. It is proved that holomorphic functions on Ω are dense in H2(Ω,φ) when Ω is the intersection of a finite number of Carathéodory domains and φ is a subharmonic function on Ω. If Ω = Cn and φ is approximately circular polynomials are dense in H2(Ω,φ).

Abstract:Let KnK1,k be a graph obtained from Kn and an additional vertex v by joining v and k vertices of Kn. For graphs G and H, the star critical Ramsey number r*(G,H) is the smallest k such that every red/blue 2 edge coloring of KN-1K1,k contains a red G or a blue H, where N is the Ramsey number r(G,H). Let Fn=K1+nK2 be a fan graph. All critical graphs of r(Fn,mK2) are determined in this note. Also the star critical Ramsey numbers r*(Fn,mK2)=m+1 for n>m≥1 and r*(Fn,mK2)=2m for n≤m are obtained by discussing these critical graphs.

Abstract:A mean reversion version of standard entry exit model with stochastic ship value was adopted to study ship investment timing, which can be expressed in terms of Kummer function. The cost and revenue data of Panama containership on Far East to North western Europe lane from 2001 to 2012 was applied for empirical analysis. It shows that recovery and peak stage are suitable for investment. The ship value and investment threshold decrease while risk free rise, which means the investable time extend. The result coincides with containership orders in the market, which is about a half year ahead of the actual containership investment time.

Abstract:A research of 37 industries panel data of 2003—2010 shows that environmental regulations have a significant positive effect on research & deelopment(R&D) expenditure. Besides, by categorizing 37 industries according to carbon emission and the R&D intensity, we find environmental regulations have a significant positive effect on R&D expenditure for both high and low carbon industry, middle R&D and low R&D industry, “Porter Hypothesis” works here on the whole, which suggest that a “win win” situation will present upon more stringent environmental regulations and the industrial technical innovation in China.