Abstract:Some methods for determining the critical excitation direction of structures regard the response along principal axes of components as the judging criterion, which have some limitations in the practical engineering application. To fill in this gap, a resultant responsebased method was proposed. Based on the response spectrum method, formulae for this method were derived. A typical horizontally curved bridge was selected as the case project, and the finite element model for this bridge was built. The critical excitation direction of the bridge was assessed by applying the resultant responsebased method and the results derived from this method were compared with those obtained from the linear time history analyses at multiple ground motion orientations. Results indicate that the resultant responsebased method can comprehensively reflect the variation of mechanical performance of the bridge component with the seismic excitation direction and has advantages of minor computational efforts and higher reliability. When regarding the resultant response as the judging criterion, adopting the excitation directions recommended by the current code for dynamic analyses of curved bridges can satisfy the seismic design requirement of practical engineering.

Abstract:Protection retainer with fusing pins used in isolators often lead to asynchronous failure owing to the brittle fracture when a group of pins are employed. Stress concentration in the necked zone may cause fatigue failure under functional loads. A protection retainer with tensile fusing units was presented in the study, in which the external lateral load was transferred as tensile force exerted on the fusing units by a deviator. The tensile fusing units had certain length of necked section that provides essential ductility to prevent brittle fracture. Smooth section transition with relatively large radius was used to enhance the capacity in resisting fatigue loads. Static tests on shear pins, tensile fusing units and the new retainer with multiple tensile fusing units were conducted. The results showed that the tensile fusing units have much larger ultimate deformation capacity than the shear pins and the ductile capacity of the tensile fusing units can be adjusted with different length of the necked zone. The tested retainers exhibited consistent ultimate loading capacity as predicted by the theoretical equations and small discreteness with repeatability tests. This indicates that the tensile fusing units in the retainers can work in sync. Furthermore, fatigue tests on the shear pins and the tensile fusing units were conducted and the results showed evidently higher fatigue resistance of the tensile fusing units.

Abstract:Bridge section reliability analysis method is reasonably carried on with the fusion of structural health monitoring data. Firstly, the vinecopula models considering the nonlinear correlation of multiple monitored variables were established based on the extreme stress data at the multiple monitored points of bridge section, which make the extreme stress data fusion achieved. Secondly, the vine copula models considering the nonlinear correlation of failure modes about bridge section were built with the performance functions about the multiple monitored points, further, through combining the built vine copula models with first order second moment (FOSM) method, the bridge section reliability considering the nonlinear correlation of failure modes was analyzed. Finally, the monitored data of an existing bridge was provided to illustrate the proposed model and method. The results show that the obtained bridge section reliability with considering the nonlinear correlation of failure modes is bigger than that without considering the correlation of failure modes. It is illustrated that the obtained results without considering the correlation of failure modes are conservative.

Abstract:Based on the bridgestitching project of Jiyang viaduct, Shanghai, an experiment was conducted on highstrain hardening ultrahighperformance concrete (UHPC) stitching joints. Asymmetrical loading was used to simulate the bridge uneven settlement in the experiment. The experiment results show that the entire process can be divided into three stages: elastic stage, cracks developing stage and failure stage. First, cracks appear under the UHPC panels; then, many micro cracks appear on the side of the UHPC panels. The cracks appear in the form of microcrack clusters, and the crack width slowly increases. When the UHPC panel rotation is 1.2%, the crack width is 0.16 mm, so the UHPC has excellent crackcontrol ability. In the end, the main crack appears at the bottom of the UHPC panels, and the transverse reinforcements yield because the reinforcement layout satisfies the requirements of the failure mode of the specimen. Thus, the reinforcement arrangement of the specimen is reasonable. The experiment was simulated using the finiteelement model, and the results were coordinated with experiment results. The parameter analysis was carried out by the finite element method, and the results show that increasing joint free length and reducing joint thickness can effectively enhance the bending performance of joints. Because the advantages of the UHPC joint are convenience, rapidity, and excellent performance, a joint form based on the type of nonconnection of upper and lower structures is put forward. What’s more, a detailed reinforcement scheme is given, which will serve as a reference for similar projects in the future.

Abstract:To study the applicability of DIJPs (ductileiron joint panels) suitable for deepburied drainage shield tunnels, positive bending moment tests for HSSJs with two different types of DIJPs were carried out, and the mechanical properties of DIJPs and the failure modes of HSSJs were analyzed. The experimental results show that: the failure characteristic of HSSJs subjected to positive bending moment, which is similar to the failure characteristic of the compressionbending section with large eccentricity, is that the bolts or the DIJPs yield firstly, and then the segmental joint fails with the concrete in the compressive zone broken. If the flexural rigidity of the DIJPs is sufficient, there is no deformation in the DIJPs, the bearing capacity of the segmental joint is higher, and the anchor bars reach their full potential; if the flexural rigidity of the DIJPs is insufficient, 5 mm bending deflection appears in the DIJPs, the bearing capacity of the segmental joint is lower, and the anchor function of anchor bars is not fully exploited.

Abstract:Taking the coast from the Xinkai estuary to Nanshan as a study object, the artificial headlands and a beach nourishment project including underwater sandbars will be constructed to reduce coastal erosion. MIKE 21 was employed to establish tidal current and wave model, hence the responses of current and wave to artificial headland and beach nourishment project can be obtained. The velocity in front of headlands can be increased due to jetlikeflow, however, the velocity inside of the headlandbay is decreased, and a weak circulation appears in the back of the headland. After the beach nourishment, wave height increases at the crest of sandbar, while it decreases between and behind sandbars with more decreasing behind sandbars. Wave height decreases in front of the berm, and has more reduction during flood period than ebb period. The combined effect of artificial headland and beach nourishment project can effectively reduce the tidal currents and waves in the area encircled by headlands and sandbars, especially near shore, hence reduce coastal erosion.

Abstract:The paper aims to investigate the realtime crash risk based on the High Definition Monitoring System data on G15 Freeway in Nantong, China. Matched casecontrol method and parameter filtering method based on random forest were utilized to build SVM (support vector machine) models for the crashes on three subsegments respectively. Results show that the SVM models based on high definition data collected by High Definition Monitoring System show better performance than those in existing studies. The transferability research was also conducted to verify the transferability of the proposed SVMs and results indicate that the models can be transferred to a certain extent. They could be applied in realtime crash prediction process on road segments nearby after the calibration of the parameters in the models and the transferred models have relatively higher prediction accuracy.

Abstract:Commuters’ travel preferences and road network traffic states synthetically have direct impact on the efficiency of travel demand management measures. On the basis and analysis of the deficiencies and merits of staggered work hours and flexible work arrangement, a new demand management named time segmenting commuting was proposed which includes three periods and two adjustments. The new management allows traffic managers arrange work start time distribution for all companies with the consideration of commuter’s preferred work start time. With collected preferred work start time and commute information of representative commuters in Shanghai, the acceptability of time segmenting commuting has been investigated. Then the work start time distribution was adjusted and analyzed according to the proposed adjustment which improved its efficiency and feasibility.

Abstract:From the perspective of commuters, the commuting distance was divided into three groups including long, medium and short commuting distance and a unified evaluation criteria about the acceptability of travel time was used in this article. From five dimensions of door-to-door travel speed, general cost, reliability, satisfaction and choice ratio, various traffic mode chains in three group of distance are analyzed. Based on the results of correlation analysis between the travel speed, reliability, general cost and satisfaction for each group of commuting distance, judgment criterion of the adaptability was established and the traffic mode chain with good adaptability was selected. Finally, with the characteristic of the traffic mode chain with good adaptability as reference objects, optimization guidance for each traffic mode chain in long, medium and short commuting distance was proposed under the constraint on prior development of public transport, which was used to provide decision reference for the improvement of commuting traffic service.

Abstract:A video-based framework was presented to collect trajectories of objects at intersections. Firstly, a modified ViBe algorithm was used to extract the foreground of moving objects. Then, an OPC(ObjectPointContour) matching approach was developed for paring, tracking and generating image trajectories. Finally, real world trajectories were obtained through perspective transformation so that velocity and acceleration could be estimated. The framework was stable to occlusion and stagnation. The accuracy of 88.89%, 86.00%, and 83.33% were obtained for vehicles, bicycles and pedestrians counts and 91.71% for velocity estimation. This automatic system provides a solution for data collection and video analysis for intersection safety management and research.

Abstract:In order to provide an intuitive understanding of passengers' experience in urban rail transit, a perceptible and identifiable index system of passenger satisfaction evaluation was established from the perspective of passengers, and the Criteria Importance Through Intercriteria Correlation (CRITIC) method was adopted to achieve objective index weighting. The primary algorithms of cloud model theory were used to generate the evaluation cloud and the result cloud, which can more intuitively represent the evaluation results by the digital features of clouds and comparison of cloud figures. Finally, the passenger satisfaction evaluation of Shanghai Metro Line 2 was taken as an example to verify the validity and rationality of the evaluation approach, while the comprehensive evaluation result not only reflected the degree of passenger satisfaction, but also provided a measure of the difference in passenger perception and degree of consensus, making it more valuable to use.

Abstract:A security method for vehicle communication network based on controller area network with flexible data-rate (CAN-FD) was established with data encryption and intrusion detection. Secure communication protocols for vehicle network including secure transmission, secure boot, time synchronization, and key distribution were proposed, and a network simulation model was established to verify the validity of the secure protocols. Secure communication nodes based on hardware instance were established to test the actual communication performance and encryption performance of the hardware nodes. Aiming at the potential attack modes of the vehicle communication network, the Dolev-Yao intruder model attack and the denial of service attack were used as the test methods to test the security of communication model and verify the intrusion detection function. And the judgment index of the network intrusion detection was determined. The experimental results had confirmed the security and usability of the method.

Abstract:A closed-loop production line has a constant number of pallets (work in process, WIP) flowing through its workstations and buffers. The performance of a closed-loop production line depends not only on the machines’ reliabilities and buffers’ capacities, but also on the constant number of pallets. This paper presents an analytical method to approximate the production rate of an unbalanced closed-loop production line with finite buffers. The machines have deterministic processing times and multiple failure modes. A decomposition method was used to divide the whole line into multiple two-machine-one-buffer blocks, and the failure modes influencing the blocks are related with the constant number of pallets. An exact algorithm to calculate the production rate for continuous systems was introduced to approximate the production rate of the discrete systems. Then, interruption of flow equations and resumption of flow equations were used to iterate the whole line production rate until converging. At last, cases analysis and comparison with simulation results were used to validate the method. Especially for unbalanced closed-loop production line with different workstation time, the method also has high accuracy.

Abstract:It was supposed to employ hydrostatic bearing technology for rocket thrust vector control system, to bring its loaddeflection resistance and low friction merits. However, the rockets always worked in serious conditions with much higher and largerspan temperatures, causing the hydrostatic bearing full of gas and much compressible, which contributed to the piston rod response overshoot and vibration. If the overshoot was too large, the oil slick will broke and lost its radial force holding feature. The present paper work modeled the piston rod dynamic motions and obtained the system transfer function with equation partlinearization, to conduct a detailed investigation of hydrostatic bearing dynamic behavior. It was found that, higher oilsupply pressure assures higher radial force holding ability, but meanwhile the overshoot response would be more likely to occur. Reasonable bearing cavity depth would prevent the response overshoot and maintain the force holding ability. Moreover, a cone shape design of bearing cavity would reduce the leakage.

Abstract:The thermal environment inhomogeneity of the cabin in winter night was studied by the method of combining experiment and numerical simulation. The temperature and velocity inhomogeneity of the cabin in different air supply modes were obtained. Then, based on Stolwijk human thermal regulation model, the Berkeley thermal comfort evaluation model is adopted to simulate the thermal comfort state of passengers, and the thermal comfort under two air supply modes was analyzed. Finally, the actual air supply condition, the isothermal air supply condition based on the same enthalpy and the uniform thermal environment condition based on the equivalent flow in front of the driver were compared and analyzed. It is found that the occupant is more likely to be in an uncomfortable state in an uneven thermal environment.

Abstract:When a compartment fire, it is impossible to monitor the safety of pedestrian effectively, a method of pedestrian’s finegrained behavior recognition based on builtin sensors of smartphone was proposed. In this method, the multisensors of mobile phone were used to collect the data of the pedestrian’s characterization. After detecting the abnormal subsequence, the feature vectors were extracted. Then, the algorithm of KeyDTW and the models of classifying were respectively used to recognize and understand the pedestrian’s activities. Next, comparing the ability of classifying in different position of device and in various combination of smartphone sensor. Finally, analyzing the pedestrian’s current status of physiological, psychological and positional. The method will provide much valuable information for the rescue operation. The results of experiments showed that the method has higher accuracies and efficiencies of activity recognition.

Abstract:The gravity satellite missions launched have the limitations in insufficient spatial and temporal resolution, spacetime aliasing, and anisotropy of the gravitational field signals. The orbit altitude, the orbit inclination and the intersatellite range of GRACEtype gravity satellite formation were simulated and analyzed. The numerical analysis of the impact of two GRACEtype gravity satellite constellation on the spatial and temporal resolution of gravity field was carried out. The results show that, considering the signal attenuation of gravity field and the life of the satellite, the satellite formation orbit altitude is better at 300~400 km. The choice of the orbit inclination should consider the influence of the polar gaps sufficiently, and the gap size should not exceed 6°. Also, when the intersatellite range is greater than 250 km, the improvement of the gravity field accuracy is not obvious, and the intersatellite range is excellently set to 50~100 km. Besides, the constellation including two GRACEtype gravity satellite formation can effectively enhance the spatial and temporal resolution of the earth's gravity field at the same time to achieve isotropic exploring of the timevariable gravity field.

Abstract:To study the movement characteristics of gravity currents propagated submerged vegetation, taking the vegetation in natural rivers as prototype, and front velocity of gravity currents represented velocity of gravity currents. The results showed that gravity currents propagated the short vegetation (length 30 cm, height 3 cm), it ridded on the top of vegetation and moved forward, and then contain the typical contour outflow the vegetation; presented a movement process that accelerated first, followed by uniform forward, then decreased , and finally slowed down. When gravity currents propagated the long vegetation (length 80 cm, height 6 cm), part of it was blocked behind the vegetation and only a part of gravity currents out of vegetation and moved forward, represented the process of first accelerating, then uniform velocity, then rapidly decelerating, and finally slow velocity. The movement process of gravity currents was divided into slumping phase and selfsimilar phase, and the blocking effect of vegetation can reduce the position of slumping phase translated into selfsimilar phase, and transform position was negatively related to the barrier effect of vegetation, but it was not related to the density of gravity currents. The vorticity values at the interface between gravity currents and environmental water was positive, and it was negative at the interface with horizontal bed. When the vegetation had a strong blocking effect, the mixing and entrainment effect was weak after gravity current propagated out of vegetation, and the outflow positively correlated with the density of gravity currents.

Abstract:The accelerated simulation pricing theory of variance derivatives under generalized auto regressive conditional heteroskedasticity(GARCH) stochastic volatility model was studied. Based on the analytical solution under the BlackScholes model and their moments analysis of these two kinds of processes, a more efficient acceleration technique of control variate was proposed and the method of selecting optimal control variate was also given. The numerical results show that the proposed accelerated simulation method of control variate effectively reduce the simulation error and improve the computational efficiency. The algorithm can also be used to solve the computational problems of other complex products under GARCH stochastic volatility model, such as Asian option, Basket option, Capped variance swap, Corridor variance swap and Gamma variance swap, etc.

Abstract:An international hydropower EngineeringProcurementConstruction(EPC)contractordesigner alliance model was established based on literature review to investigatethe cooperation methods between international hydropower engineering enterprises in China. Correlation analysis, hierarchy luster analysis and typical analysis have been adopted to analyze the data collected by questionnaires and interviews. The results addressed the interactions of the alliance factors and the relationships between incentives, alliance, and strategic partnership, which validated the model, and revealed the mechanism of alliance. The results of the survey data analysis demonstrate that: ① joint tendering is the basis for indepth cooperation between the contractor and the designer. After successfully wining the bid, two parties equitably allocate rewards/risks to enhance trust. Based on trust, effective communication is promoted, which enables the efficient circulation of information between the two parties, and thus allow problems encountered in project implementation to be solved in a timely manner. ② Alliances are underpinned by incentives, which promotes the development of partnerships; at the same time, a good partnership facilitates the implementation of incentives. The cooperative partnership between the contractor and the designer established in the implementation of the project lays a good foundation for longterm strategic cooperation. After the successful delivery of the project, the contractor and the designer are driven by incentives to share the project benefits, which helps them to establish a strategic alliance that enables joint tendering for future EPC projects, facilitating the expansion of their share of the international market.