Abstract:By using the building information modeling(BIM) theory, a whole process BIM system was designed for support and hanger structures. The functions of the system include solid modeling, calculation analysis, unit checking, output calculation result, data interface, drawings and material statistics. All of these functions share the data. What’s more, the system uses the threedimensional intelligent modeling technology based on dynamic capture and automatic parametric design, which makes the modeling efficiency be greatly improved.

Abstract:By taking the Yan’an East Road Tunnel overhaul project as the background, the principles, procedures and methods of structural evaluation for the overhaul of shield tunnels were put forward based on data investigation, tunnel disease onsite detection and analysis, and performance evaluation requirements. A multilevel evaluation index system and process of environment, material, component and structure was established, and severed for the overall performance evaluation. Meanwhile, aiming at the special evaluation requirements of the sections with large convergence, by employing the comprehensive lattice theory and Diana finite element analysis method, a cross scale simulation method of material, component and tunnel structure was put forward. The cracking characteristics of shield tunnel lining structure and the changing law under different convergent deformation conditions were analyzed, and the convergence deformation of shield tunnel was established.

Abstract:Based on the engineering background of the Xiamen Metro Line 2 tunnel, the similar model test and the finite element numerical simulation were used. Aiming at the shield tunnel’s unloading conditions on both sides, the transverse deformation characteristics, failure modes and segment damage process of tunnel were analyzed, and the stress mechanism and the key performance points of shield tunnel under unloading condition were obtained. The results show that: the convergent deformation value of segment concrete crack width 0.15 mm of design allowable value is 3.29‰D (D is the diameter of the tunnel); the vertical section of bolt failing to yield is 10.67‰D, the structural failure form is caused by segment cracking, bolt yielding to excessive deformation and collapse.

Abstract:The shear stress characteristics of the interface between coarse sand and structure were quantitatively analyzed and discussed by using the multifunctional interface shear instrument. The colored sand strips were fixed into a shear box to characterize the movement of sand particles during the tests. The results show that the spatial distribution of shear zone after shear experiment could be reflected by the color sand strips. The thickness of the shear zone formed in the shear experiments are about 6~11 mm, and the thickness of the shear zone increases with normal stress. The spatial distribution of the shear zone is irregular. In the shear direction (X direction), the shear zone exhibits a tendency that shear zone is thick at the central position and thin at both ends of the shear box. The thickness of the shear zone is approximately uniform in the vertical shear direction (Y direction). Under the friction action between particles, the sand particles in the groove drive the sand particles nearby to move together and thus the shear zone is formed during the tests. The dilatancy of sand is caused by the deformation of the sand particles in the shear zone. The dilatancy rate is fast at the initial of the experiment, and then the dilatancy rate slows down after the shear strength reaches the peak.

Abstract:Based on the stress analysis of a free body with a multi-keyed joint at the web of segmental precast concrete bridge, the shear stress distribution on the root of multi-keys at the joint was analyzed and derived. According to the elastic theoretical analysis, a non-uniform factor of shear stress at the root of multi-keys was proposed and used to modify the AASHTO formula of shear strength of the joint with multi-keys. The comparison with the numerical analysis results shows that the modified formula can accurately reflect the change trend and peak effect of shear stress in multi-keys. Moreover, the differences between the calculation results of the proposed modified formula and the relevant test results are within 5%.

Abstract:Based on the design of immersed tunnel of Shenzhen-Zhongshan Link, a refined nonlinear finite element model of immersed tunnel segment was built and a shear test was simulated. The results show that, in the transverse direction, the transverse steel diaphragm and the concrete bear the tension and compression, respectively, forming the main truss system. While in the longitudinal direction, no obvious lateral stress distribution is shown. The angle steel connectors mainly transfer the shear forces between steel and concrete, while the uplift forces are comparatively lower. At elastic stage, the shear stiffness of angle steel is close to each other and the shear force distributions are uniform. After the concrete near connectors cracking, the shear force undertaken by the structure is still increasing. In the whole shear process, the concrete cracks in bending area, the concrete cracks near the connectors, the yielding of transverse steel diaphragm, and the concrete diagonal cracks under shear occurred to the structure successively. The structure reaches the ultimate shear capacity with diagonal cracks, leading to the failure of the structure.

Abstract:Based on the state-of-the-art of high-rise wood structures and wood-concrete hybrid structures, combined with the performance superiority of cross-laminated timber (CLT), a hybrid structural system made of CLT shear wall and concrete core-tube was proposed. By using the finite element method, the effect of different parameters on the mechanical properties of the hybrid structure was studied. The results indicate that the variation of connection stiffness of CLT plates has great influence on the vertical displacement of CLT system. The increase of connection stiffness of CLT shear walls can significantly reduce the vertical displacement of CLT shear wall and the lateral displacements of global system. With the increase of concrete core wall thickness, the horizontal drift of global system decreases by 9.07% on average, but it has little effect on the vertical displacement of CLT system. The change in the number of floors, to some extent, has great influence on the global structural periods and the lateral drifts, but it has little effect on the vertical displacement of CLT system.

Abstract:A two-dimensional hydrodynamic and sediment transport numerical model for a narrow small estuary, i.e. Feng River Estuary, was established based on Mike21 and well validated by field measured data. The model was used to study the characteristics of hydrodynamics and sediment dynamics in the Feng River Estuary and its adjacent coastal water. The response characteristics of sediment evolution in the narrow small estuary under a designed one in 50-year storm wave were mainly discussed. The results indicate that under the action of pure tidal current, the estuarine channel generally presents the evolution trend of “silting up and scouring down”, mainly caused by tidal asymmetric sediment transport. The sediment evolution in the estuary is controlled by tidal currents in the normal weather, while it is controlled by storm waves in extreme weather condition. Under the normal wave-current interaction, the sediment evolution in the estuary is similar to the one under the pure tidal current. The sediment suspension is significantly enhanced under a designed one in 50-year storm wave coupled with tidal current, especially for SE and E direction incoming waves. The erosion mainly appears in the coastal area, while the deposition emerges in the estuarine channel and the siltation thickness is one order of magnitude higher than that under the pure tidal current action.

Abstract:Based on the data from Shanghai naturalistic driving study (SH-NDS), traffic flow characteristics data and driving behavior samples in freeway off-ramp areas were extracted. Illustrated by the example of 8-lane freeway off-ramp, considering the road traffic environment and exiting lane-change route for modeling purpose, a proportional odds model was adopted to fit the lane-change risk model of off-ramp areas. Based on the model, the lane-change risk graphs were drawn to visually describe the lane-change risk distribution characteristics, providing a theoretical decision support for traffic flow management.

Abstract:In order to increase both of the accuracy and the robustness for freeway short-term travel time prediction, as well as easing the over-fitting effect, which was brought by the extra training, a hybrid model was proposed on the basis of wavelet neural network and Markov chain. The forecasting performance of different models was examined by three measures, i.e., mean absolute error, mean absolute percentage error, root mean square error. The results show that the proposed hybrid model enjoys obvious superiority over the other models after the break point of travel time. Furthermore, no predictiondelay was observed in the prediction of break point of travel time. In conclusion, the higher prediction accuracy and the better robustness were found in the hybrid model in peak hours.

Abstract:Driving style analysis was conducted based on the operation data of a car-sharing project located in Shanghai. Rather than high resolution driving behavior data in most driving style studies, low-frequency trajectory data were utilized. The relative speeding time ratio and its coefficient of variation on urban expressways were used as feature variables. K-means clustering algorithm was used to classify driving styles. A total of three categories were concluded, which are calm, moderate and aggressive with the percentages of 54.04%, 36.60%, and 9.36% correspondingly. Then, for the purpose of understanding different driving styles, comparison analyses were further conducted from the aspects of trip characteristics, vehicle operation features, and personal information. The results show that drivers with distinct styles have substantial differences in their trip and vehicle operation characteristics. The aggressive drivers tend to drive faster, holding higher speeding tendency but better vehicle energy efficiency. Besides, no statistically significant differences in age, gender or violation between driving styles are identified.

Abstract:The many-to-one situation that each vibration moment corresponded to the scoring moment for a time lag was transformed to a one-to-one situation that each vibration process had only one representative time lag. The effect of the time lag on subjective scorings was tested and regressed. A fractional order calculus was then introduced to capture the effect of vibration history and the order that gave the best prediction precision for subjective scorings was chosen as the best order. Test results revealed that a short time lag does not influence the subjective scorings, while a longer time lag can have a significant effect. A structural behavior function was then adopted to arrive at a better description of the relationship between the time lags and the subjective scorings. If 0.7 and 0.3 order integration are used for the frequency weighted principle acceleration and angular velocity respectively, an 11.9% improvement can be achieved in the precision error. It reflects that humans are sensitive to cumulative vibration.

Abstract:Based on the temporal and spatial correlation of detector data, the explanatory variables were dynamically selected for data repair model, and an improved modification method of missing data was proposed considering periodic trend and real-time variability comprehensively. The proposed method was assessed with the data of locationspecific detectors in Shanghai, China. Compared with support vector regression(SVR) model, the mean absolute error of three detectors are reduced by 3.80%, 3.40%, 25.23%, and the mean absolute percentage error is less than 6% under different data missing conditions.

Abstract:An architecture optimization method was proposed for a compound power-split hybrid system. Kinematic, dynamic, and efficiency analyses were conducted for the optimized system. Then its various operation modes were introduced. A cosimulation platform was developed using Matlab/Simulink and LMS AMESim. Simulation results show that, fuel economy and power performance of the system are both improved. Energy consumption of an urban driving cycle(UDC) in pure electric modes decreases by 8%. Fuel consumption of new European driving cycle (NEDC) in hybrid modes decreases by 6%. Maximum vehicle speed in pure electric modes increases from 110 km?h-1 to 160 km?h-1. Acceleration time of 0~100 km?h-1 in hybrid modes is shortened from 14.5 s to 10.0 s.

Abstract:Based on a two-cylinder mechanical pump diesel engine, combined with self-developed high pressure common rail injection system, in-cylinder high temperature water injection system and high performance control platform, the effect of water injection temperature on combustion and performance of diesel engine was investigated. The results indicate that, by improving water injection temperature from 25 ℃ to 160 ℃, the evaporation rate of in-cylinder water vapor is enhanced, the mass of in-cylinder work fluid is improved, therefore, the work during expansion stroke can be optimized about 49.5 J, and an 8% enhancement in thermal efficiency of the diesel engine can be achieved. Meanwhile, the optimized water vapor evaporation speed is beneficial to the decrement of combustion cyclic fluctuation.

Abstract:A bearing fault diagnosis model based on improved stacked recurrent neural network was proposed, which takes advantage of great nonlinear fitting capability and the characteristics of propagation though time. Gated recurrent unit was used to deal with the vanishing gradient problem, which contributes to classify the bearing health condition. The data set from Bearing Data Center of Case Western Reserve University was used to carry out the bearing fault diagnosis test. Support vector machine, particle swarm optimization-support vector machine, back-propagation network, AlexNet, and recurrent neural network were tested as well for comparison. The results show that the proposed model has exceptional reliability and generalization.

Abstract:Based on the gas flow theory, according to the gas state equation and mass equation and the flow characteristics, the mathematical model of the re-inflation process of wagon brake system was established. Then, the model was verified on an intelligent simulation test platform. The experimental curve is basically in agreement with the simulation curve. The re-inflation process of the first and tail vehicles of 150 trains was investigated, and the variation characteristics of the vehicle reinflation mitigation process at different positions of the train were obtained, and the time difference between train tube and brake cylinder at different positions was tested.

Abstract:The measured acceleration data of vibration in rail vehicles show strong non-normality, and Johnson’s law is used to improve the criterion of inducing vibration data. A universal induction method of vibration spectrum is proposed in this paper. By using the measured data, the difference between the ordinary method and the modified method is compared, and the universality of the method is tested. The results show that the modified method can adapt to the non-normal environment and the induced spectrum can reflect the actual vibration.

Abstract:Resource investment problem with resource window constraint was considered in the context of aircraft mobile assembly line. A mathematical model was proposed to solve the problem with the objective of the total cost minimization of resource. Firstly, based on the characteristics of the resource window constraint, a constructive heuristic algorithm with non-critical activity priority decision rules was developed to solve small-scale problems. Secondly, a genetic algorithm, which was coded by a double-linked list including non-critical activity priority and critical activity start time and decoded by non-critical activity priority decision rules, was proposed for the large-scale problems. Finally, numerical experiments were carried out to compare the advantages and disadvantages between heuristic algorithm, genetic algorithm and CPLEX, and the effectiveness of the two proposed algorithms was proved.

Abstract:Dynamic correlation multivariate stochastic volatility(DC-MSV) model was adopted to study the dynamic correlation and risk spillover effects among domestic and oversea oil shipping stock prices, freight rate and stock price index. The empirical analysis shows that there are high positive correlations between oil shipping stock price and freight rate, as well as stock price index, both in domestic and oversea markets. The freight rate and the stock price index have the equal influence on the domestic oil shipping stock price, while the US counterparties are mainly affected by the freight rate. However, the index’s impact on the price of domestic oil shipping stocks has declined since 2013. The index’s impact increases significantly while the stock index fluctuates dramatically. Both the freight rate and the Shanghai Composite Index should be tracked when investing in domestic shipping stocks, while only freight rate needs to focus when investing in US counterparties.