Abstract:Taking the mudflat enclosure project， located behind the Changxing submerged breakwater in the Yangtze Estuary， as the research object， indoor dynamic triaxial tests of the silty soft clay were conducted at different confining pressures and different combinations of dynamic and static stress based on the soil samples of the dam foundation and the actual load stress path. Besides， the strain and pore pressure properties and strength weakening characteristics were explored under the coupling effect of wave force and vertical hierarchical construction action. The research results show that the stress-strain curves in the coupling stress path appear to have the properties of strain softening and strength weakening. Moreover， the strain increment and pore pressure increment decrease on account of the graded loading effect. The strain increment， the pore pressure increment， and the strength weakening after cyclic loading are related to the confining pressure， the static deviatoric stress ratio， and the dynamic deviatoric stress ratio. Corresponding to the same deviatoric stress ratio， when the soil layer is shallow， the confining pressure is smaller， on the contrary the static deviatoric stress ratio is larger， hence the greater the strain increment and pore pressure increment will be， along with the more obvious static strength attenuation. With the increase of dynamic deviatoric stress ratio， the strain increment， the pore pressure increment， and the degradation of strength after cyclic loading increase， with a more obvious deviation of different depths. Based on the results，the degradation of strength β， the generalized shear strain γgs and the generalized composite pore pressure increment ratio Δu/σ3 were quantified respectively. Furthermore the relation between (β-γgs) and (β-Δu/σ3) were explored. The research results have certain reference value for guiding specific engineering practice.

Abstract:In order to extend the application of self-anchored suspension bridge， a novel type of partially anchored suspension bridge was proposed based on externally anchored suspension bridge and self-anchored suspension bridge， and the basic performance of the structural system was studied. The main research contents include structural analysis based on the deflection theory， parameter analysis of static performance， natural vibration characteristics， and design method of anchorage. The results show that the static performance of partially anchored suspension bridge is between the externally anchored suspension bridge and the self-anchored suspension bridge， and the gravity stiffness is provided by the anchor cable tension when the bridge is formed. Under the action of live load， the increment of internal force of main cable is distributed in the anchor cable and the main beam according to their stiffness， which reflects the characteristics of “partial anchor”. The structural system can adjust the force state by actively tensioning the anchor cable， and the beneficial effect of passive earth pressure can reduce the weight of gravity type anchorage. Partially anchored suspension bridge is especially suitable for special positions with limited construction conditions. The tensioned and adjustable anchor cables provide a new scheme for design and construction. It can be concluded that partially anchored suspension bridge has certain advantages.

Abstract:Researchers can rarely answer the question of how people choose between in-store shopping and e-shopping， let alone predict future changes in retail market. Thus， this paper aims to find an approach to explain the mechanism of shopping channel preference of residents and simulate scenarios in the future. 512 residents in Shanghai were investigated and 4 608 virtual shopping channel choices were made in total. The discrete choice model can well explain how people choose a certain channel in specific shopping situations. The five factors considered in the questionnaire include the price， quality， shopping time， travelling time， and the type of stores， which significantly affect the choice of shopping style. The shopping attractiveness evaluation indicates that e-shopping is more attractive than in-store shopping in general in recent years in Shanghai. Based on the simulation results of three probable future scenarios， it is speculated that e-shopping is likely to continue to experience a period of rise in the near future and then experience a certain cooling-off and eventually reach a relatively stable state.

Abstract:To fill the gap that the traditional autopilot disengagements （ADs） frequency model has underestimated the driving ability of autonomous vehicles in road testing， this paper first proposed the concepts of risk-avoiding disengagements and non-risk-avoiding disengagements and then determined the disengagement temporal threshold by using the nonparametric rank sum test. Three characteristic values including average speed difference （ASD）， instantaneous speed difference （ISD）， and short-term speed difference （SSD） were considered as the indicators to quantify the differences of the behavior of vehicles before and after disengagements. Thus， the K-means clustering algorithm in unsupervised learning was used to distinguish the two ADs types. The risk-avoiding disengagement frequency （RADF） model for assessing the driving ability of autonomous vehicles in road testing was finally created. Based on the empirical data covering scenarios of urban road and expressway in Shanghai， the RADF model is verified. The results show that based on the RADF model the driving ability of autonomous vehicles in road testing has averagely been increased by 4.8 and 7.3 times respectively in the urban road scenario and expressway scenario， compared with the traditional ADs frequency model.

Abstract:To improve the safety of freeway traffic in adverse weather， a method for determining the freeway recommended speed under adverse weather based on safety risk is proposed. Considering the influencing factors of traffic safety risk， a traffic risk assessment model is established based on Bayesian logistic regression， while the fuzzy C-means clustering algorithm is used to classify the traffic risk and obtain the risk threshold. A two-step calculation method for safe vehicle speed under different weather conditions is proposed. Firstly， the 85 %th vehicle speed of the vehicle running speed in the traffic flow state where the risk is less than the threshold is selected as the initial safe driving speed. Then， the principle of parking line of sight is used to correct the speed， in order to obtain the final recommended speed of the freeway in adverse weather. Taking G15 Shenhai Expressway （Shanghai section） as an example， the recommended speed of the freeway under different visibility conditions in foggy days is given.

Abstract:This paper aims to optimize traffic organization in the off-ramp affected zone of urban expressway， reduce the lane-change risk of leaving vehicles and thus improve the safety and efficiency of traffic operation. Based on the dataset from Shanghai Naturalistic Driving Study （SH-NDS）， the trajectory data samples of leaving vehicles in the off-ramp affected zone of expressway were extracted and lane-change risk evaluation method and classification standard were established. Targeting at three types of off-ramp areas of expressway， a lane-change risk model was established by using the binomial Logistic model， considering comprehensive factors in terms of drivers， vehicles， road and environment. Therefore， the influencing degree of different factors was revealed and lane-change risk probabilities were obtained. Based on vehicle operation information and lane-change risk model， reasonable（latest） lane-change positions of leaving vehicles were calculated and corresponding lane management methods were proposed when lane-change risk was within a certain range.

Abstract:This paper studied the cracking performance of ultra-thin friction course mixtures with different gradations and asphalt content by utilizing indirect tensile asphalt cracking test （IDEAL-CT）. The results show that denser gradation would cause a higher mixture strength and a worse resistance to deformation， as well as a faster crack propagation， indicating a worse cracking resistance of mixture. With the increment of asphalt content， the deformation resistance of mixtures was enhanced and the crack propagation was postponed， which revealed that the cracking resistance of mixture was enhanced. The Pearson correlation analysis indicates that with the increment of air voids and asphalt film thickness， the strength of mixture decrease， the resistance to deformation is enhanced and the crack propagation is decreased， resulting in a better cracking resistance performance. Therefore， the air void and asphalt film thickness are recommended to be raised to improve the cracking resistance performance of mixture during ultra-thin friction course design. For the indicators of IDEAL-CT test， the fracture energy is not appropriate to evaluation of the cracking resistance performance of ultra-thin friction course mixture.

Abstract:The distribution law of the vertical wear of frog nose rail is analyzed based on test data and literature， and the vertical wear profile of the frog nose rail in each level were created according to this distribution law. Aimed at the 60 kg?m^－1 rail No.12 single open turnout of ordinary railway， a heavy haul train-turnout coupled dynamical model was established based on the theory of vehicle-turnout coupled dynamics to calculate and analyze the influence of the vertical wear of the frog nose rail on dynamical wheel-rail contact in frog area when the heavy haul train passes through the turnout. The results show that the region where the top width of the nose rail is 20-40 mm is the region where the vertical wear is more serious. With the increase of the vertical wear of the frog nose rail， the maximum of wheel-rail contact force in the wheel load transition area and the volatility of contact force curve in the transition area generally are increased， even the wheel-rail contact relationship is deteriorated， and the smoothness of the wheel load transition between the nose rail and the wing rail is decreased. When the track geometric irregularity is good， the vertical wear of the frog nose rail top width of 40 mm should be controlled within 5 mm.

Abstract:In order to improve the dynamic wheel-rail interaction of turnout crossing and reduce damage on the nose rail， an optimization method for the height of the nose rail was proposed based on the wheel-rail contact characteristics. This method aims to reduce the wheel-rail contact forces of turnout crossing as the design goal， to ensure the safety of the vehicle and the monotonicity of the longitudinal height of the nose rail as the constraints. The particle swarm algorithm was used to solve the optimization model， which had a faster convergence speed. The results show that the optimization method can quickly design the height of nose rail that better matches the wing rail according to the rail profile of turnout crossing， the heightening value of the wing rail and the tread profile. Moreover， the optimized nose rail can improve the wheel-rail contact relationship， thereby reducing the wheel-rail impact when the vehicle passing the turnout crossing.

Abstract:Because the modeling process using air dispersion model （AERMOD） for transportation environmental impact assessment has a high potential for analysis error， it is necessary to examine the differences between area and volume source and contrast the low-resolution receptor placement with high-resolution receptor placement. The mechanism of exclusion zones in volume source is analyzed and a method for avoiding the negative effects of exclusion zones is proposed. The results indicate that it is easy to create analysis errors using the volume source， which is largely caused by the effects of the exclusion zones. It is also found that higher densities of receptors better capture the characteristics of concentrations， especially at the locations near the emission source.

Abstract:A regenerative braking strategy was designed for a distributed drive vehicle with a centralized motor drive on the front axle and a hub motor on the rear axle， namely Strategy 1. According to the power transmission process in a braking， the concept of the total efficiency of the power generation system was proposed， and the optimal front and rear motor force distribution coefficient was obtained based on its maximum of it. Then， under the constraints of ECE（Economic Commission of Europe） regulations， the regenerative braking economic optimization strategy was designed， namely Strategy 2. For vehicles equipped with ABS（Antilock Brake System）， when the braking strength is small （z<0.2）， the rear axle motor can be preferentially used in regenerative braking. Therefore， an economic optimization strategy at low braking strengths was proposed， namely Strategy 3， to make the most of the efficient area of the power generation system. The analysis demonstrates that the proposed strategy has little effect on braking feel. The simulation results show that the energy consumption of the three strategies is reduced by 14.05%， 15.04% and 16.64%， respectively.

Abstract:Based on the distributed electric drive system， a handling improvement method was designed for a distributed drive electric coach using torque vectoring control. In view of the large load transfer， the strong coupling characteristics of tire， the suspension， and the steering system during coach corning， the relationship among equivalent lateral force， aligning torque， and the tire sideslip angle were described respectively by using polynomials. A mass estimation algorithm was designed to modify the lateral stiffness when the vertical load of the wheel changed. The vehicle reference steering characteristics was defined considering vehicle nonlinear characteristics， and the feedforward term of torque vectoring control at different steering angles and speeds was designed. In order to improve the robustness of the controller， an anti-integral saturation sliding mode variable structure control law was used as the feedback item of the torque vectoring control. The simulation and experiment results show that by using the proposed controller the vehicle steering characteristic is closer to neutral steering， and the mean value of peak steering angle in slalom test is reduced by more than 21%， which means the handling performance is significantly improved.

Abstract:To solve the problem that the ferrite core is easy to be saturated and has a poor mechanical performance in high power applications， a novel flexible high-saturation nanocrystalline core is adopted. However， due to low resistivity， nanocrystalline has a strong eddy current in the 85 kHz alternating electromagnetic field. To reduce the eddy loss， a refinement crushing process and an alternating seamless stitching process are proposed. Based on finite element simulation analysis， the feasibility of the modified process has been preliminarily proved. Four schemes of nanocrystalline cores with different permeabilities are compared with ferrite. The static parameter analysis and 7.7kW power transfer test indicate that the modified nanocrystalline cores perform well. Moreover，the nanocrystalline core with the best performance is adopted for anti-saturation test and leakage measurement at 11kW. Even when its thickness is decreased to 2mm， the AC-AC efficiency is still 97.408%. The maximum temperature of core is only 80.9℃， and flux leakage completely meets the limit requirements of ICNIRP 2010. In contrast， the ferrite core cannot withstand the action of a strong alternating field and is broken.

Abstract:In view of the defect that traditional four-node membrane element cannot bend， a novel four-node membrane element model with bending modification was proposed based on the equilibrium principle of element internal forces and bending moments. The new element is applied in the one-step algorithm for bus rollover collision to improve the initial algorithm. A case study on the rollover of a typical bus body section is conducted using the improved algorithm. The validity of the proposed improved element is examined by comparing the computational results of the improved algorithm with that of the original algorithm， LS-DYNA， and the rollover test on the side of computational efficiency and precision.

Abstract:In view of the problem of the poor control in traditional proportion integration differentiation （PID） control and the classic Smith prediction method in train deceleration control， the feedback structure of Smith estimator was improved， and the uncertain factors that affect the actual deceleration of the train are classified from the perspective of control system. A single mass point simulation model for train braking was established， and its step response characteristics under the control of PID， Smith estimator and improved Smith estimator were analyzed. The simulation results show that the improved Smith estimator has a better control performance and a higher robustness. Finally， based on the software in the loop simulation， the control effects of non-deceleration control， deceleration control based on improved Smith estimator method， and deceleration control based on adaptive parameter estimation algorithm were compared. The results show that the deceleration control based on the improved Smith estimator can not only achieve accurate tracking of the target deceleration， but also significantly reduce the longitudinal impact of the train.

Abstract:To solve the problem of skidding due to the deterioration of adhesion conditions during train braking， a novel anti-skid control method based on adhesion force observer was proposed. Using the observer to observe the use of adhesion force in real time during braking， and based on the slip ratio of the wheelset and the deceleration of the vehicle， an anti-skid controller was designed to control the wheel slide. The Polach model was used to simulate the wheel-rail adhesion force to verify the controller. The results show that the anti-skid control method proposed can accurately observe the use of adhesion force under the conditions of continuous low adhesion and two-step changes in adhesion. Besides， the degree of sliding of the wheelset can be effectively controlled and a better use of adhesion is realized. During the anti-skid process， this controller can also modify the braking force continuously， so that the brake cylinder pressure can be adjusted smoothly， which avoids frequent and cycled charging and discharging of compressed air.

Abstract:The frequent switching of tooling/fixture， tool/gauge and system utilizationse cases in the multi-variety mixed-model production line under the mode of "industrial 4.0" intelligent manufacturing can easily lead to abnormal production and short-term stopping risk in workstations. First， the mean residence time（MRT） was proposed by analyzing the uncertainties caused by product polymorphism in the multi-variety mixed-model production line. Next， this study by considerings the minimum production cycle of the MRT multi-variety mixed-model production line， establishes the product operation schedule based on the sequence of products entering the production line， and establishes an intelligent sequencing mathematical model by introducing the key variables of MRT to the objective of minimal cycle optimization. After that， based on the Palmer principle， an improved genetic algorithm was designed to solve the intelligent sequencing problem of the multi product mixed-model production line. Finally， the feasibility and validity of this method are verified by an example.