Abstract:A parametric analysis using ABAQUS was conducted to study the effects of different buckling restraint measurements on the local buckling of steel plates in boltedsideplated (BSP) beams. The results show that the buckling behavior is not sensitive to the initial imperfection of the bolted steel plates; thicker steel plates result in a greater buckling strength; less bolt spacing and larger longitudinal stiffeners improve the buckling strength and decrease the lateral buckling camber; the buckling restraint caused by transverse stiffeners is ignorable; and the enhancement of buckling strength beneficial from longitudinal stiffeners can be divided into the yield strength of the stiffeners and the buckling restraint effect. The proposed fitted formulae can evaluate the buckling strength accurately.

Abstract:A numerical simulation of still circular tube and dynamic singledegreeoffreedom (SDOF) circular tube was performed to study the vortexinduced vibration (VIV). The results show that in still case between the Reynolds number of 20k to 35k, the mean value of lift and drag coefficient amplitude are 1.472 and 1.273, respectively, which are in consistent with previous experimental investigations. The formation of vortexstreet is determined by the interference of the shear layers. The alongwind response is far less than acrosswind response during VIV. Based on the feasible SDOF model with dynamic mesh and relevant formulas, the 2D simulation is applied to fatigue analysis of 3D steel tubular members.

Abstract:Fourteen HRB 500 reinforced RPC beams worked on concentrated load were tested. The influence of shear span ratio, steel fiber content, stirrup ratio, reinforcement ratio, and reinforcement strength was considered. The shear capacity formula and its simplified form based on the plastic theory were concluded. The shear capacity values of the beams were predicted and compared with the test values and the results of current codes. The results show that by using the formulas based on the plastic theory, the shear capacity of RPC beams can be well predicted. The results of the simplified formula are not very discrete which is suitable for engineering. The results of current codes are all conservative. But the ideas of material strength correction in CECS 382004 are worth learning.

Abstract:In order to obtain the effect of temperature on the residual stress in welded high strength Q460 steel sections, the Hsection and boxsection Q460 steel members were heated by using electric furnace and then cooled naturally to room temperature. The residual stresses were measured by using the sectioning method after the steel member cooling. For comparison, the residual stress in the steel member without heating was also tested. The magnitude of residual stresses after being exposed to high temperature were obtained as well as the reduction factor of residual stress exposed to various temperatures. The effect of reduction in residual stress on the load bearing capacity of Q460 steel columns at elevated temperature were analyzed by employing ANSYS. The study shows that temperature has a great influence on welded residual stress. As the temperature increases, the residual stress is more reduced. The reduction of residual stress has a significantly effect on the load bearing capacity of Q460 steel columns in fire, and the design value of load bearing capacity can be enhanced by 10% in comparison with the load bearing capacity without considering the residual stress variation.

Abstract:A blockage correction method for group tall building models in the wind tunnel test is proposed based on the wake area method (WAM) applicable to the single tall building model. First, the flow patterns of group buildings and the basic assumptions are demonstrated. Then, the correction formula of the blockage effect is derived to extend WAM to the group building arrangement with two or more buildings. Finally, the parameters in the formula are fitted using the test results of typical group building arrangement, such as two and three square tall buildings with the same height, in the uniform flow. The method proposed is verified by the correction of the mean pressure coefficients of the target building in different cases. The WAM for group buildings can meet the needs of construction projects with high accuracy.

Abstract:To alleviate the traffic congestion problems on urban freeways, a method is proposed to determine the control priorities of coordinated onramps metering of urban freeways using the risk assessment techniques and the QHM(quantitative hierarchical model) to classify a freeway corridor into subsections. The priority matrix is constituted by the density ratio of the current status of the subsections over the critical status and is used for the determination of control priorities of multiramps of freeway corridors. It can ensure the smoothness, fairness and consistency among subsections. Finally, the reliability and the feasibility of the proposed model is verified by the case using the Vissim simulation.

Abstract:Under the circumstance that the cross section width of truck escape ramps is 4.5 meters, 7.7 meters, 9.0 meters, and 12.2 meters, fortyeight groups of motion parameters of motor vehicle driven onto truck escape ramp by 5 drivers were obtained by driving simulation UCWin Road Ver.9. Then, the minimum turning radius, adjusting time, steering angle amplitude, steering angular frequency, and the bending position were extracted using steering velocity index, steering wheel angle, and lateral migration rate. The correlation between the above five indexes and cross section width, operating speed and interaction of cross section width, and operating speed were analyzed by using two ways ANOVA. After that, the significant test of the five indexes at different cross section widths were analyzed by multiple comparison. The research result indicates that the minimum turning radius, steering angle amplitude and steering angular frequency of 4.5 meter cross section widths are significantly different from the other three groups. Errant vehicles are in sideslip risks when their operating speed just reaches 90 km?h-1 at the 4.5 m cross section width. At the same time errant it is difficult for the driver to drive the vehicle into the truck escape ramp successfully and the driver suffer from severe psychological tension. The bending position is prior to the starting point of the transition segment only when the cross section width is 12.2 meters. And the difference between bending position and transition starting point is more significant compared with the other three groups. The cross section width has a significant effect on adjusting time which has a significant differences at different widths. There exists a power function relation between adjusting time and cross section width. Comprehensive analysis shows that the cross section width of truck escape ramp should not be less than 7.7 m.

Abstract:Compound corridors is the main component of large public buildings. In order to quantitatively describe the pedestrian traffic flow characteristic at compound corridors, and solve the pedestrian traffic problem in public buildings, the queue waiting for service at compound corridors was described as a queuing system, and a mathematical model to calculate the pedestrian flow rates was built based on the analysis of parameter characteristics. The pedestrian service level is evaluated combining with the HCM method and based on the investigation data obtained from Jiageng Stadium station in Xiamen and a university mess hall.

Abstract:Based on the noise vibration multichannel realtime acquisition analysis system, the noise sources of the highspeed train surface were tested and analyzed using the planar microphones and highintensity microphones, when the running speed of the train was over 300 km?h－1. The two line sources at the bottom and middle of the train and the point sources for pantographs were equated to the sound source of highspeed train. The noise reference levels of the three sources were determined by the least square method and the theoretical calculation of train through noise test data, based on which, the model of highspeed railway noise prediction was established under multisource mode. At the moment, the highspeed train was running on an embankment line at a speed of 300 km?h－1. The validity of noise prediction was checked against experimental results, with good agreement. The results provide theoretical basis for establishing the systemic model of highspeed railway noise prediction.

Abstract:The flow and heat transfer performances of thermalhydrolyzed sewage sludge in twisted oval tubes were numerically investigated and the mechanism of enhanced heat transfer was analyzed in this paper. The velocity and temperature distributions at different aspect ratios and twist ratios were obtained, and the effect of Reynolds number on the flow and heat transfer was clarified. The results reveal that the heat transfer efficiency could be greatly increased by the generation of vortex and secondary flow but with the growth of pressure drop. Furthermore, a larger twist ratio leads to a smaller thermal performance factor, and as the aspect ratio increases to 1.96, the thermal performance factor reaches the maximum value and then descends. By compared with the results of smooth round tubes, the twisted oval tubes show much improved heat transfer efficiency at a low Reynolds number(<5 000).

Abstract:Vermifiltration is an ecological technology that is applied to decentralized wastewater and excess sludge treatment. Filter media significantly influence physiological and ecological functions of earthworms and microbes. At the organic loading (mass concentration of volatile suspended solids) of 2.11 kg?(m3?d)-1, the effects of the three filter media (wooden bead, porcelain ball and pall ring) on excess sludge treatment performance were investigated by exploring the variations of enzymatic activities of earthworms and of microbes. The results demonstrate that the VSS reduction by three earthworm biofilters can meet the requirement of execess sludge treatment (upwards of 40%). Notably, earthworm biofilters filled with wooden bead can offer the best habitat for earthworms and microbes. The SOD and ACP of earthworms have the lowest and highest values of the fiter media, respectively, indicating that earthworms suffer less adverse effect from wooded bead filter material. Furthermore, the highest DHA value of microbes also suggest that the wooden bead is the optimum filter material for biochemical degradtaion concideration. The earthworm enzymatic activities of superoxyde dismutase are the lowest and the acid phosphatase and the microbe dehydrogenase enzymatic activities are the highest. This indicates that and microbes perform best their degradation function. Therefore, wooden bead is good for performance of earthworm biofilters.

Abstract:In this paper， a controller is designed for steerbywire systems to achieve the desired steering angle of front wheel. The controller is designed based on the nonlinear characteristic of the selfaligning moment generated by the tyre cornering forces and uncertainty of system parameters. Besides, the constraint of actuators is taken into account. A feedforward and state feedback controller overcoming integral saturation is designed with conditional integrators to achieve the desired steering angle. Based on the nonlinear control theory, a Lyapunov function is built to prove that the steeringbywire control system is asymptotically stable. In the end, the steering angle tracking algorithms proposed are verified by real vehicle tests.

Abstract:A complicated vehicle was applied to make a further research of the influence of wheel spoiler height on vehicle aerodynamic drag. Two different conditions including stationary and rotation were employed in computational simulation by steady RANS (Reynolds Averaged NavierStokes) calculation. Further, detailed analysis of the flow around wheels was conducted. It is concluded that the aerodynamic drag coefficients are all increased after the decreasing along with the increase of the height of wheel spoiler. After the height optimization, the front wheel spoiler can improve both the vehicle aerodynamic drag coefficient and the heat dispersion ability inside the under hood, providing guidance for engineering application.

Abstract:Mileage is a major technical bottleneck in the application of electric vehicles. Therefore, improvement of the efficiency of the motor drive system is a key technology to breaking through the bottleneck. High power losses and low efficiencies of the inverter can not only affect the mileage of electric cars, but also cause high cooling system load of electric vehicles and limit the current output capacity of the inverter. In this paper, the sevensegment SVPWM, flattop SVPWM, and halffrequency SVPWM are compared and used in combination. That is, different modulation algorithms are used under different working conditions of electric vehicle, which makes the system have a low inverter loss and high torque accuracy, so as to improve their market competitiveness.

Abstract:In this paper, a high speed oilfree centrifugal compressor for the 65kW fuel cell powertrain system application is selected as optimization objective. The impeller profile curve is parameterized with Bezier curve, and the latin hypercube sampling method is adopted to build the sample space for genetic algorithm optimization. Based on these pretreatments, the Kigring model is built for multioperating condition optimization. The optimization and CFD calculation results show that both isentropic efficiency and pressure ratio are improved, especially under common operating condition. For the centrifugal impeller of traditional internal combustion powertrain, it is always believed that the isentropic efficiency at both rated and common operating condition cannot be improved at the same time. However, impeller aerodynamic analysis and multioperating condition optimization indicate that this view is not suitable to the fuel cell powertrain system. The optimization based on parameterized impeller profile achieves a higher isentropic efficiency compared to the optimization based on impeller geometrical parameters, which shows that the optimization based on parameterized impeller profile is a more comprehensive and efficient method for centrifugal impeller optimization.

Abstract:This paper aims to build a 3D micro structure of carbon paper gas diffusion layer (GDL) based on morphological parameter of true materials. This method needs to acquire the basic morphological parameter first by scanning the true GDL structure. Then, by confirming the center coordinates of the whole 3D GDL structure, it constructs a layer of fiber structure each time through the loop and stops when reaching the true thickness. The fiber in each layer will be overlapping and intersecting. After finishing the reconstruction, it needs to be transferred to the binary image that is convenient to fluid modeling. This structure model is used to test the permeability, and the results obtained from the stochastic reconstruct method is very close to the results of the true image. From the case study, the permeability characteristic effect with the change of each structure parameter is given. These results will be used for the structure optimization and improvement of the diffusion of GDL structure.

Abstract:The traction and braking calculation and kinematics related theories were used in the study of the electric multiple units(EMUs) braking calculation method. According to the deceleration characteristic of the EMUs braking system，the error of the approximate braking calculation was analyzed. The EMUs calculation method was proposed based on target deceleration，unit basic resistance，gradient resistance, and other related parameters. This method is proved correct in comparison with the system performance type test data of CRH6A EMUs. The result shows that the calculated braking time and braking distance are consistent with the test result, which is effective to support the design and development of EMUs.

Abstract:Let α(G), β(G) and n(G) be the independence number, the matching number and the order of a graph G, respectively, the independence number and the matching number are two more important parameters for a graph. In this paper, it is proved that there exist two optimal numerical relationships between them for the graphs which are K3free and the maximum degree is 5 at most.

Abstract:In this paper, finite element analysis for a class of neutral delay parabolic equation is considered. Based on a linear finite element space, one semidiscrete and two full discrete finite element schemes are constructed for the neutral delay parabolic equation. Then, the L2 norm error estimates of the semidiscrete and two full discrete schemes are obtained by the projection operator. Numerical experiments proves the validity of the theoretical analysis.

Abstract:Based on the investigation of five trade associations in Shanghai, this paper uses structural equation to analyze the effect of intellectual capital on the performance of trade association. The empirical results show that among the three elements of intellectual capital, human capital and relational capital have a direct significant positive effect on the internal and external performance of trade associations, but structure capital has little effect on the internal and external performance of trade associations.

Abstract:This paper develops and implements a dynamic house pricing model and stochastic interest rate model for Lump sum pricing model and equal payment pricing model of reverse mortgage products for the empirical research of Shanghai. A vector autoregressive model(VAR) for economic variables including house prices index, CPI and GDP based on the data in Shanghai is used to better capture the interrelationship between economic variables and simple prediction. The Nowman’s CKLS model is also used to represent the stochastic interest rate. The present value of net pay off of Lump sum reverse mortgage to assets profitability is computed. The commonly risk measure VaR(Value at Risk) is used to analyze risk in order to give an index to solvency and liquidity.

Abstract:Influential factors, behaviors and objective performances of smart city construction are exploratively studied by using the grounded theory method based on text sources from the literature at home and abroad. A theoretical model about action mechanism among smart city construction influential factors, behaviors and objective performances is obtained based on the above analyses. Besides, the initial scales of influential factors and objective performances about smart city construction are built. Furthermore, the initial items of questionnaires with a small sample of pretest and reliability tests are modified, and the final items are formed by using exploratory factor analysis. The confirmatory factor analysis of these scales, tests of theoretical model and research assumptions are empirically conducted by questionnaire design and investigation. Finally, the main research conclusions are reached and policy suggestions are proposed.