Abstract:Tests of six groups of flushed and extended endplate connections using blind bolts were carried out. Based on the existing research results, the stiffness formulas of blind bolts in tension, end plate in bending, column wall in tension, column wall in compression and end plate in compression were derived. The theoretical calculation formula of the initial rotational stiffness of flushed and extended connections under bending moment was proposed by means of the component method. The results show that the calculation formula of the initial rotational stiffness of connections is in good agreement with the test results, and the precision can meet the requirements of engineering design. Finally, the design proposal of Hshaped steel beams to rectangular hollow section(RHS) column endplate connections using blind bolts was put forward.

Abstract:In the light of velocity pulse characteristics of nearfault ground motion and the dominated vibration mode to the dynamic response of floatingsystem cablestayed bridge, a threemass simplified dynamic model was derived and the differential dynamic equation was established. Based on the method of equivalent damping ratio and equivalent linearization of nonlinear viscous dampers, design formulas for determining the damping coefficient of nonlinear viscous dampers of the bridge subjected to nearfault ground motion were deduced. Finally, the accuracy of the proposed design formulas for nonlinear viscous dampers in predicting the damping ratio of the bridge was verified by a real cablestayed bridge.

Abstract:A variable crosssection prestressed concrete continuous girder bridge with a span of (55+4×90+55) m as the research object was analyzed, and the dynamic analysis model of the bridge was established by using the software ANSYS. Three artificial seismic waves were selected as seismic input. Based on dynamic nonlinear analysis method, the seismic response of the bridge and the hysteresis performance of the bearing considering friction effect for nonbrake piers were analyzed. Then, the seismic respose of the bridge considering friction effect was compared with that without considering friction effect. The results indicate that the basin rubber bearing at nonbrake pier has a regular and full hysteresis curve under seismic action, and the shape of the hysteresis curve is approximately rectangular. After considering the friction effect of the basin rubber bearing, the longitudinal bending moment and the shear force were reduced by 25.91% and 27.41% respectively at the bottom of nonbrake pier. The longitudinal displacement at the top of brake pier and the pierbeam relative displacement of nonbrake pier were reduced by 26.15% and 25.59% respectively. If the friction energy dissipation of sliding bearings is not considered for the multispan and longunit continuous beam bridge with multiple sliding bearings whose reaction force is large, the seismic response of bridge structure will be larger and the seismic design will be too conservative.

Abstract:Based on the Fick’s second law, a diffusion reaction equation of sulfate in concrete piles was established. With the method of separation of variables and Danckwerts, according to initial conditions and boundary conditions, the diffusion reaction equation was deduced. Furthermore, considering the effect of pore filling and crack on diffusion coefficient, an effective diffusion coefficient model was proposed to show the variation of the diffusion coefficient during the degradation process of concrete piles. Sulfate concentration profiles were obtained by the solution and the effective diffusion coefficient model, which agrees well with the experiment data to verify the validity of the proposed analytical solution. Case study shows that the inhibition effect of pore filling on sulfate diffusion is remarkable. The development of the crack promotes the diffusion reaction of sulfate. With watercement ratio decreasing, the invasion depth of sulfate decreases, as well as the concentration of sulfate in concrete piles.

Abstract:Parameters affecting the failure modes of reinforced concrete (RC) columns were investigated using low frequency cyclic loading experimental data from 469 reinforced concrete (RC) columns. A method using shear span ratio and moment shear ratio as parameters was proposed to classify the failure modes of RC columns. With reference to the current codes for seismic design, the performance states of RC columns were divided into seven levels. And the method for determining the deformation limits of these levels were put forward. The proposed method was based on three key performance points (point of yielding, point of losing 20% load capacity, point of losing bearing capacity) of the forcedisplacement backbone curves. Regression analyses of deformation limits of RC column, considering multiple combination of parameters, were performed using the collected test data of 469 RC columns, and deformation limits of RC columns of different failure modes were put forward using the most statistically significant regression formula. The proposed deformation limits were then evaluated using fragility analysis method. Finally, quasistatic tests on 11 RC columns were conducted and used to verify the proposed deformation limits. The results show that the accuracy, the discreteness and the failure probability of the deformation limits are all within reasonable range.

Abstract:In this paper, the origin and the development of modeling method are studied based on critical simulation problems. The detailed process and the improvement of major methods are reviewed. The efficiency and the results of simulation are compared by introducing “interference check indicator” and “the shortest path ratio”. It is shown that the distributions of concrete aggregate with vertical subsidence are different under gravity, which affects the durability of material and needs to be simulated by corresponding methods. The parameters including density and aspect ratio are important in mesoscopic study and should be adjusted according to practical aggregate. The review of methods can guide the selection of largescale and highprecision modeling and normalize the results from different methods and parameters, which can simplify the complex analysis significantly.

Abstract:A wavecurrent coupling model was established based on Delft3D software for Zhonghaitan Beach coastal water and verified by tidal current and wave measurement data. Thus the hydrodynamic changes due to artificial sandbars were modeled and investigated by the verified model. The main conclusions can be drawn as follows: tidal current field only shows changes around the bars since the tidal effect is originally weak in the research area; four sandbars dissipate wave energy and dissipation function increases with incident waves; on the whole, the artificial sandbars reduce the effect of hydrodynamics and contribute to beach maintenance.

Abstract:The Tongji University Driving Simulator was used to conduct experiment and collect speed data. Speed change was divided into three intervals: substantial speed decrease, steady speed (minimal change) and substantial speed increase. Multinomial Logistic models were used to investigate the relationships between geometric design characteristics of combined curves and adjacent segments and speed changes. The results show that: for combined curves, it is more difficult to maintain speed as the lengths of combined curves and the mean grades of combined curves increase; the probability to increase speed is higher when combined curves are downslopes; the probability to maintain speed is higher when combined curves turn left; it is more difficult to maintain speed as the grade changes between the preceding segments and the combined curves increase; the probability to decrease speed is higher when the curvatures of the following segments increase.

Abstract:Based on the principle of inertia reference method, a kind of dynamic measurement system assembled on a vehicle was proposed to realize the measurement for the vertical irregularity of high speed maglev track. It is verified that the system can meet the requirements of measurement error within ±0.2 mm. As the detection surface was the cogging structure type of long stator of synchronous machine, an effective algorithm was put forward to reduce “cogging effect”. As a result, it can reduce the measurement fluctuate within ±5 mm which is caused by the cogging structure. Finally, according to the requirement of measurement, the selections of related sensors in the system were analyzed and the preliminary consideration of platform design was discussed.

Abstract:A dynamic controller based on antiwindup proportionalintegral (PI) algorithm for skidsteered vehicles was designed. The dynamic characteristics of skidsteered vehicles were analyzed, and a double closedloop lateral dynamic control method was proposed to improve the control performance which was influenced by the complex and varied tireroad adhesion conditions. The simulation and experiment results show that the proposed dynamic controller has good transient and steady tracking performance, which can track the driver’s intention accurately.

Abstract:Based on the multi-body dynamics method, a transient dynamic model of brake creep groan was proposed. In this model, the brake system, the suspension system, the structure and spatial position of equivalent transmission system and the brake friction characteristics were considered. The driving torque from transmission system and the brake pressure were regarded as inputs. The stickslip motion and phase diagram of disc against pad, the vibration of key components in brake and suspension system were obtained. In addition, the key transfer path analysis was clarified. The simulation results indicate that the brake creep groan consists of two typical vibration modes. One is the impact mode with large magnitude and short duration, and the other is the periodic mode with lower magnitude but longer duration. The tangential movement dominants the key vibration both in brake and suspension components. The vibration is transferred by the strut and control arm to the body, resulting in the longitudinal movement of the whole vehicle.

Abstract:Aiming at the exampled fuel cell car, this paper studies the realtime optimal algorithm of energy management strategy for fuel cell car based on model predictive control（MPC） theory, with the target of improving energy economy. The simulation results indicate that the proposed MPC algorithm can effectively improve energy economy, satisfying the instantaneity of the control.

Abstract:Polarization curve, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and segmented cell techniques were adopted to investigate the performance degradation of proton exchange membrane fuel cell (PEMFC) during storage and startup processes under subfreezing temperatures(<0 ℃). The experimental results indicate that freeze/thaw cycles without gas purge during shutdown process will increase the polarization resistance and deteriorate the current density output of PEMFC. In addition, the electrochemical surface area (ECSA) of catalyst layer decreased and the uniformity of current density distribution of PEMFC worsened, which deteriorates the overall durability of PEMFC. Based on the optimized twicepurge strategy, the efficiency of residual water removing was enhanced with less gas consumption. With the aid of circulating coolant heating solution, the cold start of single cell from -30 ℃ was successfully achieved within 340 s.

Abstract:Based on the random parameter mixed logit model, a discrete choice model for customer preference heterogeneity was established for the hierarchy of autobody product. According to the sampled data obtained from SP(stated preference) survey and parameter prior distribution setting, the Markov chain Monte Carlo simulation method was used to make the Bayesian estimation of parameters. Finally, the McFadden’s likelihood ratio test proves that the random parameter mixed logit model is of optimal goodnessoffit, and better than others to elucidate where the customer preference heterogeneity rooted in. This modeling approach helps to capture personalized customer needs, and helps manufacturers to anticipate mutiple preferences of potential customers and assists in the design and the development of autobody products.

Abstract:A topology design method for the weld line location layout optimization of tailor welded blank(TWB) door is proposed in the paper. The multistiffness performance is required and the bidirectional evolutionary structural optimization (BESO) is considered as the basic design algorithm. Thus, the traditional interpolation model with Young’s module is changed into a novel model with thickness property. Finally, the sensitivity equations are derived from different stiffness requirements. The results show that the region boundary of different thicknesses is more obvious and the total weight of optimized door reduces by nearly 30% with only about 1% loss of its stiffness.

Abstract:An experimental study on the effect of width (W) and edge distance (E) on singlelap, singlebolt, ［0°/90°］4s epoxy carbon fiber reinforced plastics (CFRP) with highstrength steel DP980 joints is presented in this paper. Failure processes and failure modes of the CFRP/DP980 joints bearing tensile loads are studied. It is found that the failure modes largely depend on the width and the edge distance of laminates. The width of laminate has a great influence on the stiffness of joint, while the edge distance has little. Within a certain range, both the width and the edge distance have a great influence on the joint strength. When the ratio of width to hole diameter is larger than or equal to six and the ratio of edge distance to hole diameter is larger than or equal to three, the strength of joint tends to a maximum value; meanwhile the failure modes are mainly bearing failure. CFRP laminates are sensitive to secondary bending.

Abstract:Based on surface magnetic element integral theory, a fast highprecision magnetic forward method was proposed to solve the magnetic fast forwardmodeling of magnetized unexploded ordnance with different shapes and positions, by using triangular surface element method and spline interpolation method. The method realized the fast interpolation forward modeling of finitelength cylinder and variablediameter finitelength cylinder. It is shown that the error of the method is relatively small compared with that of noninterpolation method.

Abstract:Through the filed profiles and the trace fossil assemblages from well core, we found that the lake stratums of Yanchang Formation in Ordos Basin were mainly developed in eight relics types: vertical dwelling trace (Skolithos and Cylindricum), vertical browsing trace(Scoyenia), Utube trace (Arenicolites), burrow trace (Planolites, Chondrites and Teichichnus), horizontal trace (Protopaleodictyon), escape trace（Fugichnia）, nekton trace and root trace. It is shown that the distribution and assemblage of trace fossils matches the sedimentary environment of the Late Triassic lake basin in Ordos Basin, reflecting the geological value of the restoration of lithofacies palaeogeography by the use of trace fossil assemblages.

Abstract:Focusing on China’s patentintensive industries, we measure the patent intensity and its economic contribution from the level of threedigit industry code. Then, we analyze the effect of human resource, capital input and research and development activities on the value of patent intensity. The results show that China’s patentintensive industries have obvious differences in development level and present the economic situation of “almost all industries are weak excepted for some star industries”. In addition, human resource is the most significance factor, followed by research and development activities and capital input. Lastly, this paper gives an insight into the optimization of input structure for policymakers, in order to promote industry sustainability development.

Abstract:In a multi-channel supply chain composing of a dualchannel retailer and a pure online retailer, a Stackelberg masterslave countermeasure game model with the pure online retailer as a leader and a Stackelberg masterslave countermeasure game model with the dualchannel retailer as a leader were built respectively. Then we focused on two factors including the electric market scale and the proportion of the dual-channel retailer’s electronic market scale accounting for total electronic market scale, and studied the impact of the factors on the optimal pricing of supply chain members in different strategies of pricing timing. Finally, the changing trends of the prices of the channels in the equilibrium were discussed with numerical analysis. The results indicate that the optimal pricing level of both retailers’ electronic channel increases with the increase of their respective electronic market scale. If the pure online retailer sets the direct price before setting the price for the dual-channel retailer, the optimal pricing strategy of the dualchannel retailer is to adopt the low-price strategy of omnichannel firstly, and after the market scale of electronic market is expanded to a certain extent, the low-price strategy of traditional channels will remain unchanged and the price of electronic channel will be gradually increased.