Abstract:Performance degradation of concrete bridges in atmospheric environment is closely related to material damage caused by carbonation and forces. In order to evaluate quantitatively the effects of the two actions, the authors summarized the material damage models. Besides, the method for analyzing long term evolution of the concrete bridge performance was proposed and a finite element program was written in this paper. A prestressed concrete simply supported beam in atmospheric environment was investigated. The results show that both carbonation and forces have significant effect on the long term performance of the bridge, which include the loss of the cross section area and deterioration of the mechanical behavior. When considering the effects of carbonation and mechanical damage, the section loss, deflection, and degradation of flexural capacity at the mid span were more serious than those when only carbonation effect was considered.

Abstract:Based on some engineering practices of long span arch bridges in China, static wind loading of a typical arch rid by using segmental evaluation method and the equivalent static wind loading with respective to the buffeting and vortex induced vibration by using the inertial load method were investigated, as well as the comprehensive evaluation of total wind loading for the arch rib and main deck was conducted. Results show that the segmental evaluation method is reasonable and practical in evaluating static wind loading of arch ribs, and the modified Reynolds Number formulas are benefit to predict static wind loading for prototype bridges including the components of arch rib with circular cross section. Combination forms of different equivalent wind loadings were employed to analyze and evaluate the wind loading effect in different regions of a long span arch bridge.

Abstract:Experiments on 2D rectangular prisms with side ratios of 2.0, 2.5, 3.0, 3.5 and 4.0 are reported in this study. The tests were conducted in TJ 2 wind tunnel to measure the wind pressures on the surfaces of 5 models for the testing Reynolds numbers ranging from 1.1×105 to 6.8×105. Aerodynamic forces were obtained by integrating the wind pressures around the model surface. The Reynolds number effects on the aerodynamic force coefficients and the power spectrums of aerodynamic force coefficients are presented, and the influence of side ratio on the drag force coefficients is analyzed. The results show that the aerodynamic characteristics of rectangular prisms with side ratio between 2 and 4 are Reynolds number dependent, and the rectangular prisms appear to be more sensitive to the Reynolds number with increasing side ratio. The along fluctuating wind force is produced mostly by the along fluctuating wind speed, and the vortex shedding plays a second role, whereas the crosswind lift force is mainly from the vortex shedding.

Abstract:Fatigue reliability analysis method for steel crane girders is discussed in the paper. Firstly, fatigue failure limit state equations are developed in which two factors are considered such as the variable amplitude fatigue damage reduction caused by low stress range and the growth in number of fatigue cyclic loading. Next, the statistical properties of random variables in the limit state equation are investigated. Both the first order second moment method and Monte Carlo simulation technique are employed to calculate the fatigue reliability index. Then, a case study is carried out to investigate the effect of the above tow factors on fatigue reliability index. The current research results reveal that fatigue reliability index of steel crane girders increases significantly after considering fatigue damage reduction of low stress range，but it decreases as the growth rate in number of fatigue cyclic loading increases. Finally, a few of suggestions are given for fatigue design of steel structures.

Abstract:Assumed the deformation of steel truss and concrete filled tubular (CFT) column were independent, a simplified analytical model on the bearing mechanism of the joint sub assembly was proposed based on the superposition principle. And the test verification with the results obtained by the model was conducted. In the model, the steel truss was considered as a combination of the hinge and rigid mechanism, and the loaddisplacement relationship of the CFT column was calculated according to the momentcurvature equation and the equivalent shearing stiffness. Failure modes and bearing capacity could be identified according to the analysis. The predicted loaddisplacement relationship and failure modes had good agreements with the test, and the predicted bearing capacity was also close to the test. From the view of seismic performance, some discussions on the different failure modes of the structure were made in the presented paper.

Abstract:A nonlinear finite element model for numerical analysis is developed firstly in this paper, which is validated by the data from the authors’ previous experiments. Using this reliable model, then a large amount of case study is carried out to investigate the effects of seven parameters on the rotation capacity, such as end moment ratio, force ratio, web height thickness ratio, flange width thickness ratio, slenderness ratio of compressive flange, residual stress distribution pattern and degree of connection between concrete and steel. It is found that except the degree of connection, the other parameters have significant influence. Finally，a formula for rotation capacity of the composite beams considering the above influencing parameters is proposed for engineering design.

Abstract:Apply centrifuge model test and FLAC3D simulation to understand high filled project of Shanghai about the deformation law and stress mechanism of combined retaining wall that wrapped reinforced retaining wall combined with counterfort retaining wall. Centrifuge model test’s results show that the horizontal displacement of combined retaining wall is smaller, and that combined retaining wall can better control the horizontal displacement of high filling. Based on centrifuge model test, FLAC3D was used to simulate the horizontal earth pressure of combined retaining wall, and compare horizontal displacement and horizontal earth pressure with wrapped reinforced retaining wall and counterfort retaining wall with the same condition, simulation results show that counterfort retaining wall can control horizontal displacement efficiently and wapped reinforced retaining wall shares most of horizontal earth pressure. Based on the results of test and simulation, some suggestions and references are provided for the design of combined retaining wall of high filled project.

Abstract:A new two dimensional gas flow model was developed to analyze the gas migration in layered landfills. The model considers anisotropy of the municipal solid wastes(MSWs), and vertical variations in both gas generation and permeability caused by compression, degradation and inhomogeneous distribution of moisture content. The general solution of this model can be developed using eigenfunction expansion method, and the unknown integration constants can be determined by the boundary and continuity conditions. According to this analytical solution, the influences of vertical wells, horizontal lines and permeable layers on the gas pressure and recovery were further investigated. Finally, the design method of the landfill gas (LFG) collection system for layered landfills covered by geomembrane was proposed.

Abstract:The experiments of shaking table tests were carried out in order to study the evolution and mechanism during the fluidization of iron concentrate ore in bulk. And with the use of digital image capture and processing technology, the laws concerning the displacement field, moisture migration and movement of particles during the fluidization were analyzed. As a result of these two types of experiments, both macro and meso mechanism of the fluidization of iron concentrate ore were revealed. The results show that it is the dynamic loading that leads to the fluidization of iron concentrate ore. Due to the dynamic loading, the fine particles move downward through the spaces between coarse particles. At the same time, the water on the surface of particle moves down and becomes water film which flows upwards. Meanwhile, it provides the theoretical basis for the further studies concerning preventive measures for the fluidization of iron concentrate ore.

Abstract:Based on the videos of traffic flow at two bottlenecks (Hongxu on ramp and Hongjing on ramp) on Yan’an Expressway in Shanghai, 416 empirical merging behavior samples were collected by extracting trajectories from merging vehicles, as well as each adjacent vehicles. The classification and regression tree (CART) was adopted for modeling three merging situations, the key parameters affecting different merging behaviors were analyzed and the confusion matrix was used to evaluate the result of the classification accuracy. The results show that CART performed well with these data. All the accuracies are over 75%. Moreover, a comparison among CART, classical discrete choice model and naive Bayes classifier was conducted, and the CART shows the best classification results.

Abstract:Weight in motion(WIM) system is adopted to obtain actual traffic data of a four lane highway and a two lane highway (in one direction) in Guangdong Province, China. Vehicle distributions and load composition on different lanes are analyzed statistically, and spatial distribution laws of vehicle flow and load are explored. Based on the analysis, sensitivity of the asphalt pavement and bridge structure to the transverse differences of vehicle flow is discussed. Results indicated that there exists huge variation for vehicle lane choice feature. Over 70% vehicles with two axles prefer to run in the inner two lanes, and over 90% vehicles with more axles incline to travel in the outer two lanes. Traffic distribution for the inner lanes is highly concentrated, but the vehicle load level for which is relatively low; The vehicle load level for the outer lanes is far above which for the inner lanes. The pavement for the passing lane is still of good performance under the action of the vehicle load in ten years, meanwhile the pavement for the other lanes is badly damaged and demands maintenance. The maximum moment effect extreme value caused by vehicle load appears in the driving 2. For different loading lengths, the measured effect extreme values basically exceed the corresponding code values, which shows that the vehicle load model of current Chinese code cannot meet the actual demand of structural design and assessment, and need proper revision.

Abstract:A simple model based on mass balance was constructed for the prediction of fine sediment migration in activated sludge reactor under different influent fine sediment load. The results shown that, during the influence period, the predicted fine sediment concentration was mainly effected by concentration of influent fine sediment, proportions of suspended fine sediment, sludge age, hydraulic retention time and impact time. During the recovery period, however, it was mainly effected by initial fine sediment concentration, sludge age, and recovery time. The relative errors of the predicted fine sediment concentration during the influence and recovery period were between 11.7% and 24.6% , 29.1% and 46.0%, respectively. The relative errors of volatile suspended solids ratio in sludge during the influence and recovery period were between 0.9%and 7.3%, 2.3%and 34.4%, respectively. The maximum fine sediment concentration in mixed liquor and deposition rate of fine sediment are proportional to influent fine sediment load.

Abstract:Wetlands area change and ecosystem service value change for sea level rise are evaluated by using Sea Level Affecting Marshes Model. The area of Hillsborough County, Florida was taken as the case study, where the sea level is assumed to rise 1 meter from 2010 to 2100. Five affecting processes of inundation, erosion, overwash, saturation, accretion are included in the assessment model. The results show: (1) Dry lands area will decrease by 30.37km2, while wetlands area will increase by 30.37km2. Estuarine open water, beaches, salt marshes, regularly flooded marsh will increase by 394.29%, 380.62%, 141.93%, 121.41% respectively. Irregularly flooded marsh, tidal fresh marsh, tidal flats, estuarine beaches, inland shore will decrease by 95.52% , 91.31%, 59.29%, 37.59%, 21.44% respectively. Mangroves, inland open water, swamp, inland fresh marsh, cypress swamp will be less affected, which will decrease by 6.67%, 4.05%, 2.35%, 0.90 %, 0.10% respectively. (2) Although the total wetlands area will be increased, but the ecosystem services value will be reduced due to the loss of beach and freshwater wetlands, which will decrease from $ 616,720,000 in 2010 to $ 615,480,000 in 2100. The values of art and entertainment, water regulation, climate regulation, spiritual and cultural will be reduced, while values of water supply, habitat protection, disturbance regulation and waste disposal will enhanced.

Abstract:Requirement and difficulties of intra stack measurement are analyzed. The state of the art in intra stack temperature and humidity measurement is presented. Methodologies in temperature(field) measurement are micro thermocouple (array), resistive temperature detector (array), infrared image, fiber bragg gratings and phosphor thermometry; while chromatography, tunable laser absorption spectrum, micro electronic humidity sensor and fiber bragg gratings are applied in humidity measurement. Comparison of the measurement technologies shows that micro sensors have good spatial and signal resolution with low cost, while optic fiber bragg gratings benefits in chemical inertness, immunity to electromagnetic interference and multiplexing capability, which has the most brilliant future.

Abstract:Transfer path analysis is now the most common tool in noise and vibration diagnosis of a mechanical system. In order to avoid the limitations of the existing TPA methods, a novel transfer path analysis method is proposed base on the FRF(frequency response function)-based substructure dynamic characteristic identification theory. It is applied to a simplified finite element model used to simulate the powertrain and the body of a car. The dynamic characteristics of the substructures in free state and the joint properties are obtained in coupled condition by a spectral-based inverse substructuring approach. And then the coupled system behavior can be described in terms of the free substructure FRFs and coupling dynamic stiffness by FRF-based substructuring approach. Thus, vibration path contribution analysis is carried out and the dominant paths and substructure FRFs are identified.

Abstract:Theory and application of the lattice Boltzmann method (LBM) for flow field simulation in the torque converter stator cascade is studied. Firstly, treatment for rotational periodic boundary is proposed. Then, influence of different parameters on computational stability and efficiency is analyzed. In order to ensure stable calculation of migration and collision process of particles, it is essential to choose appropriate value of the relaxation time, τ to avoid occurrence of negative value of the equilibrium distribution function, feq. Furthermore, the large eddy simulation (LES) is adopted in the LBM to lessen the restriction of computational stability on the relaxation time, τ and to improve computational efficiency. Finally, flow field simulation of the stator cascade is realized by extending function of an open source code named ‘Palabos’, and instantaneous structure of unsteady wake flow behind the stator blade is obtained. The computational result shows that calculated force applied by fluid on the stator blade is nearly the same for the LBM to that of the tradition computational fluid dynamics (CFD) method. However, the LBM has advantage in calculating the forming history of flow filed and complex details of instantaneous flow structure.

Abstract:Hydrodynamic torque converter blade thickness is traditionally determined by blade empirical streamline formula. However, this method fails to represent coupling torque variation between blades and fluid, and therefore easily results in poor performance of torque converter. Based on high precision fluid structure interaction(FSI) analysis of hydrodynamic torque converter, this paper proposes a blade thickness design by evaluating converter performance. Blade thickness curve is deduced on the condition of meeting the constraints of blades stress intensity and blades thickness curvature variation. In this paper, a hydrodynamic torque converter example demonstrates that blades thickness has a strong correlation with fluid field distribution. And this method is effective on improving torque ratio, efficiency and dynamic performance, and provides a reference workflow for hydrodynamic torque converter design in industry.

Abstract:Deep study on ground effect mechanism and aerodynamic characteristics of wing in ground effect was carried out based on wind tunnel test in Aerodynamics/Aero acoustic Wind Tunnel of Shanghai Automotive Wind Tunnel Center of Tongji University. Relative motion between wing and ground in cruising was simulated by the moving belt system; span dominated ground effect was systematically investigated by changing span or taking account the endplates; stall characteristics of wing in ground effect was also discussed for different flight height and span. In the study, mechanism of ground effect was further revealed, importance of moving ground simulation was disclosed and aerodynamics of wing in ground effect was comprehensively analyzed through the experimental studies, which provide important reference for aerodynamic design and research of wind in ground(WIG) craft.

Abstract:Cushion comfort had a significant impact on driving comfort and preventing driving fatigue in driving process. When suffered factors from vehicle, road and environmental, characteristic of driver’s body pressure distribution was different from single seats. According to cab space constraint, driver's field of vision and size of seat, a driver static body pressure distribution experiment was designed and a logistic regression model was established. Finally, the relationship between cushion subjective comfort level and ankle angle, sitting height and cushion average load was investigated. This theory will provide a new basis for research about cushion pressure distribution and driver subjective comfort evaluation psychology.

Abstract:The basic hypothesis, core principal and implementation process of various types of micro dynamic model for high voltage high power PIN diode are analyzed in detail. Moreover, comparison and evaluation of models are made on the aspect of validity, convergence, accuracy, computational efficiency and difficulty of obtaining model parameters. On this basis, the improvement direction of the power PIN diode model is discussed, which will provide support for the model optimization and its applications on electromagnetic interference(EMI) pre evaluation.

Abstract:To solve the machining line balancing problem for complicated prismatic parts, the execution sequence of operations should be considered during the line balancing process. After analyzing the constraints and optimization objectives, a method has been presented, which can provide optimal or near-optimal assignment of operations to the stations and sequence of operations inside the stations simultaneously. Based on the constraints of process and workstations, taking the tool change and rotation capabilities of machine center into consideration, this problem was modeled aiming at minimizing cycle time and cost of the line. Particle swarm algorithm was use to solve this problem. A heuristic decoder was designed for the algorithm to permutate each particle to a feasible line balancing plan. Pareto set was introduced to realize the multi-objective optimization and the algorithm efficiency was improved with elitist preserving strategy. Finally, a case was illustrated to prove the validity of the proposed method.

Abstract:Based on the Gaussian Copula model with arbitrary marginal distribution in portfolio’s market risk or credit risk; To improve the efficiency in Monte Carlo simulation with importance sampling, we first transform loss to a function of a high dimensional normal vector, then the Newton’s method and a method based on the large deviation theory are used to estimate the coefficients in measure transformation, and the method of freezing coefficient is also proposed. Numerical experiments show that compared with standard Monte Carlo method, the algorithm proposed in the paper reduce simulation error greatly and therefore improve computational efficiency.

Abstract:Based on the relations between the universal enveloping algebras and affine Schur algebras, we provide a presentation for SΔ(2，3)Q in terms of generators and relations in this paper.This presentation is obtained by adding more relations to the presentation of the universal enveloping algebra.

Abstract:Three dimensional hexagonal mesoporous silica (YPS, P means H3PO4) and vesicle like mesoporous silica (YNS, N means HNO3) were synthesized by the sol gel method using H3PO4 or HNO3 as catalyst, sodium coco glycerol (YCS) as surfactant, tetraethyl orthosilicate (TEOS) as silicon source. The as prepared YPS and YNS samples were calcined at different temperatures including 550 ℃, 700 ℃ and 850℃. The prepared samples were characterized by X ray diffraction (XRD), high resolution scanning electron microscope (HRSEM), high power transmission electron microscopy (HRTEM), nitrogen adsorption and micro electrophoresis, the effects of the calcination temperature on pore size, surface area were discussed. Moreover, the influences of the adsorption isotherm and the kinetics model of laccase on YPS and YNS samples of the isoelectric point, surface area, pore volume and other parameters were also discussed.