Abstract:A new type of sunflower-type cable dome with double struts, which has the characteristics of fewer number of inclined cables, convenient tensioning forming and effective prevention of ring slip, is proposed in this paper, Based on the nodal equilibrium equation, a recursive calculation formula for the internal force of the prestressed cable strut is given. 72 examples are given, including the number of lower chord cables, the ratio of sagittal span and the position of lower chord joint of the structures. It is verified that the formula for calculating the internal force of prestressed cables is exact solution. The analysis results show that the internal force of the cable strut increases exponentially from the inner ring to the periphery. When the position of the lower chord joint changes vertically or horizontally, the internal force of the prestressed cable strut is changed greatly. When the rise-span ratio is within the range of 0.1~0.2, the influence of it is less. It is shown that rise-span ratio and the opening in the middle of the structure are non-sensitive parameters, while the number of the lower chord cable and the position of the lower chord joint are sensitive parameters, and should be considered in the design of the structure. The proposed structure provides new forms and new concept for the selection, design and construction of cable dome.

Abstract:The main beam of a Arch-beam fixed arch bridge acts as a rigid tie rod to balance the thrust of archs, but it also has the adverse effect of structural stiffness decrease. This has limited the application of this type of arch bridge on high-speed railways. In order to solve this problem, this paper proposes a new arch bridge. The method is, first of all, to add 10 rigid diagonal bars between each ribs and the main beam to form 11 triangle structures with the main beam and the each ribs segments. As far as possible, the arch ribs and the main beam are equally divided by triangular corner points so that the line stiffness of the arch ribs and the main beam are improved. Secondly, according to the original structure displacement envelope diagram, it is guaranteed that the triangular corner points fall at the position of maximum displacement and the mid-span of main beam so that the weakness of arch ribs is strengthened. Studies have shown that the overall stiffness of the new arch bridge can be significantly improved under the condition that the material increases little or even the same. In this paper, the fatigue and temperature responses are also discussed in detail, and finite element analysis shows that the structure also has good adaptability to fatigue and temperature. And the superior stiffness characteristics of the new arch bridge are particularly suitable for high-speed railway bridges.

Abstract:In order to reveal the influence mechanism of temperature dependence of development of mechanical properties of concrete in largediameter steel tube arches on the thermodynamic effect of composite structures during hardening process, a finite element model was established to simulate the hydration heat transfer process of the concrete in the steel tube arch, which was compared with the measured temperature field data. Subsequently, the effect of hydration heat on the development of the modulus of elasticity of the concrete was further considered based on the equivalent age method, by which the variation of thermal stress of composite structure during hardening process were revealed combining with thermal elasticity mechanics theory, and compared with the calculation results without considering the influence of the temperature dependence. The results show that the hydration heat temperature field accelerates the growth rate of the modulus of elasticity of the concrete in the tube during hardening, which leads to a significant increase in the thermal stress of the concrete during hardening process, and the increases in the radial, circumferential and longitudinal directions can reach 1.3 times, 1.4 times and 1.3 times, respectively, but the effect on the stress of the steel tube is negligible. Hence, in the analysis of the thermodynamic effect during the hardening of concrete in largediameter steel tube arches, the effect of hydration heat temperature field on the development of the modulus of elasticity of the concrete in the steel tube must be considered.

Abstract:This study presents results of an laboratory triaxial experimental program with respect to study the effect of wheat straw reinforcement on the shear strength of soil. Threeaxis shear tests were carried out under four reinforcement rates (0.1%, 0.2%, 0.3%, 0.4%) and three reinforced lengths (5, 10, 15 mm). The mesostructure changes of reinforced soil and plain soil during loading are compared and analyzed by using computed tomography(CT) scan image. The results show that: the shear strength and deformation resistance of wheat straw reinforced soil are significantly improved than plain soil, and the reinforcement effect is better when the wheat straw length is 10mm.In this condition, the cohesive forces of reinforced soil are 1.1 to 3.3 times that of unreinforced soil, the internal friction angle changes in the range of ±2 degrees. Compared with plain soil, the macroscopic shear failure of reinforced soil during shearing is not obvious, and all of them are bulging failure. When the confining pressure is small, the effect of reinforcement is significant, and the effect on the stiffness of soil is fine. With the increase of confining pressure, the effect becomes weaker. CT scanning results show that wheat straw reinforcement can restrict soil deformation and crack growth. It is concluded from this study that wheat straws are a suitable reinforced material for cohesive soil.

Abstract:The hydrodynamic conditions at the back of headlands in a headland-bay are relatively weak, which may be easy to cause deterioration of water ecological environment. The water environment can be improved by controlling the destination of pollutant, hence the capacity of water exchange reflects waterbody self-purification capacity. MIKE 21 is employed to establish tidal current and conservative mass transport model, in which the headlandbay coast is divided three sub-regions, and the time-scale quantitative measurement is introduced to discuss the responses of water exchange to the beach nourishment project. Due to the orientation of sandbars in the beach nourishment project is basically parallel to the main direction of current, the circulations in the back of headland are weakened, and the velocity increases at the top of the sandbars while decreases between the two sandbars. The velocity decreases in front of the berm and decreases more in the back of sandbars. The increased current velocity in the tidal inlet between artificial headland and sandbar shortens the residence time after the beach nourishment project. The reductions of residence time in the two subregions around the headlands are much larger than that in the middle sub-region. Both wave and wind promote water exchange. However, because wave is also affected by wind, the residence time under both wave and wind conditions is not equal to the linear superposition of residence time under wave condition and wind condition respectively.

Abstract:To accurately depict the characteristics of microscopic motion, and describe two-dimensional movements of non-motorized traffic flow, the comfort-zone theory was put forward for the first time to describe the generation of behavior motivation of cyclists. Besides, based on this new theory, we proposed a three-layered model to describe the movements of non-motorized vehicles from the whole process of behaviors. Comparing with empirical data collected in a physically separated road section in Shanghai and the social force model, the proposed model can reflect the microscopic features better, and the average error of trajectories is only 0.64 m.

Abstract:In order to carry out a more detailed study of driving safety on long-span bridges, based on the wind-vehicle-bridge coupling theory, the bridge vibration effects under three wind speeds are calculated and a long span bridge driving simulation experiment scenario considering both the crosswind and the vibration was established. Twenty drivers were divided into two groups according to the driving experience, and the driving simulation experiment was conducted. The results show that in the late stage of crosswind, the lateral displacement and the yaw speed of the vehicle affected by bridge vibration are larger than those without vibration. Bridge vibration effect will have a positive warning effect and adverse interference to driver, for the driver with relatively lack of experience, crosswind and vibration combination is more detrimental to traffic safety.

Abstract:Derived from revealed preference (RP) and stated preference (SP) survey results for the transit passengers, this paper developed the travel choice behavior model considering the effects on bus route operation under three types of storm waterlogging scenarios. Sensitivity analysis was also performed to evaluate the critical factors for transit passengers in choosing their travel modes, which include walk time, transit fare, in-bus congestion degree, and in-bus travel time (from high to low). And, the main features of the selected travel modes are zero transfer, low fare, easy to change traveling intention and stable operation (from high to low). These finding could have implications for developing bus emergency management plan and serve as references for public transit agency regarding bus dispatching, information announcement and traffic safeguard.

Abstract:To improve the visualization, intelligence and informatization level of traffic markings, light-transmitting concrete is introduced to highway field, and the light emitting diode (LED) active-luminous traffic marking based on light-transmitting concrete is constructed. The analysis of variance and multiple comparison methods are used to analyze the physical property, lighttransmitting rate and economy of the four types of general-purpose fiber-optic. As a result, Polymethyl Methacrylate (PMMA) fiber-optic is selected as the light-transmitting material. After that, theoretical diameter is determined according to the light-intensity distribution curve and the light-propagation path in fiber-optic. Based on the measured data of 1~8 mm PMMA fiber-optic, the S-shaped curve can effectively fit the change trend of light-transmitting rate with fiber-optic diameter, and it is consistent with the theoretical analysis results. Therefore the PMMA fiber-optic diameter is determined to be 6 mm. Based on the measured visible distance of the LED active-luminous traffic marking under different brightness, color and dosage, using logarithmic regression model, the reasonable fiber-optic dosage is determined to be 2~6 pcs when the design speed is 60~120 km?h-1.

Abstract:The stress response of concrete around dowels in airport rigid pavement under the individual action and superposition of temperature gradient and aircraft load was studied with finite element method (FEM) simulation. The model was validated by analytical equations under temperature gradient proposed by Westergaard. The results show that the dowels have approximately 15% of restraint on the deflection of the joint under temperature gradient. When the sole aircraft load is applied on the corner of the slab and above the sliding end of the dowel, the stress in the concrete sees its maximum. The maximum stress under sole load is only produced in concrete around the sliding end of dowels. Negative gradient is disadvantageous as to the stress concentration of concrete produced by aircraft load, while the positive gradient is advantageous.

Abstract:In order to consider the dynamic responses of track and subgrade of the scaled track-subgrade model and the interaction between them, a uniform dynamic similitude method for the track-subgrade system was first proposed. The dynamic similitude design of the track was conducted and the acceleration-scaling factor of the track-subgrade model was assigned as 1.0. Then, the track and subgrade follow the same length scaling factor and the shear wave of the subgrade model was controlled to perform the dynamic design of the subgrade structure. By using the proposed approach, the similitude design of a 1/4-scaled track-subgrade model system was conducted and a series of dynamic tests of the model system under the excitations with different frequencies were carried out. The acceleration responses of different positions of the model were measured and analyzed. The first-order frequency of the test system was obtained. The results show that there exists time delay in the process of downward transfer of acceleration. Under the excitations with a certain frequency, the characteristic frequencies, which were obtained by using the spectrum analysis of acceleration, of different structural layers are consistent.

Abstract:Based on the displacement correcting method, the China railway track system(CRTS)Ⅱslab track was modelled in a finite element software. The damage propagation laws of wide and narrow joint separation, mortar-layer separation and supporting-layer cracks during the correction process are studied. The results show that the wide and narrow joint separation would decrease the ability to resist damage of the bonding interface; the mortar-layer separation made little influence on bonding interface; the supporting-layer cracks would grow deeper into the inside of the supporting-layer during the correction process.

Abstract:In this paper, the driving behavior statistical characteristics of the driver are studied by using the naturalistic driving data. The longitudinal acceleration, lateral acceleration, yaw rate, and velocity of the vehicle were chosen as the characteristic parameters which were employed to describe the driving behavior of the driver. Firstly, the convergence of the driving behavior of the driver was discussed. The kernel density estimation was used to achieve the probability distribution of the driving behavior characteristic parameters. And the kullback-liebler divergence was applied to describe the distribution distinction between datasets which were composed of different amount of data. Next, the distribution characteristics of the driving behavior characteristic parameters were proposed by using the convergent dataset. In the last, the conditional distribution of the driving behavior characteristic parameters were used to study the interaction between these parameters. The conclusions can be summarized as: The forward acceleration, brake deceleration, lateral acceleration, and yaw rate approximately follow the Pareto distribution. The steering maneuver of the driver tends to be more intense when brake deceleration or forward acceleration increases, and vice versa. The steering, braking, and accelerating maneuvers of the driver become more intense and then become less intense when the velocity increases.

Abstract:Four-wheel independent steering (4WIS) electric vehicle adopts the strategy of simultaneous steering of front and rear wheels; in this paper the dynamic model of the 4WIS electric vehicle is established, and the relevant state space expression is obtained, then the linear time-varying path tracking prediction model is derived. Control algorithm is transformed into standard quadratic programming problem based on model predictive control theory, combined with constraint conditions and optimization objective function. The 4WIS path tracking controller is designed. Then the Matlab/Carsim joint simulation platform is used to carry out the simulation test under double shift line conditions. Finally, the robustness of the control algorithm to speed and road conditions is verified, and the influence of controller parameters on the realtime performance of the algorithm is analyzed.

Abstract:In the transitional conditions of hybrid braking of electric vehicle, for the impact caused by the poor cooperation between the hydraulic braking force and the motor braking force, a coordination strategy of double closedloop feedback and motor force correction was proposed. The double closed-loop feedback strategy relies on the motor force to compensate for the tracking error of hydraulic pressure of the hydraulic brake system, the purpose of the motor force correction strategy is to guarantee the motor to have the compensation capability under all transient conditions. The simulation and hardware in-loop test are carried out based on the integrated-electro-hydraulic brake system (I-EHB). The test results show that the proposed strategy can significantly reduce the impact degree in the braking force switching conditions and improve the vehicle braking comfort.

Abstract:The combustion and emissions of a gasoline direct injection (GDI) engine were studied during constant-speed and increasing-torque conditions by transient engine control and measuring system. The effects of transient throttle switching duration and amplitude were investigated. The close-loop λ proportion and integral(PI) control for fuel injection strategy and the throttle overshoot strategy were tried to show their potentials to improve the transient combustion and emissions. The results revealed there were different degrees of time lags for engine working parameters compared with throttle opening, and the longer switching duration would shorten the lags. The stabilities of the working parameters became worse when the switching amplitude was larger. The response characteristic of intake air was thought to be the major factor that affected the transient combustion and emissions. In this paper, the combination of P=0.08/I=0.5 was the best to shorten the time lag with throttle opening and reduce the particulate number and hydrocarbon (HC) emissions. Compared with PI optimization strategy, the throttle overshoot strategy could be more efficient to shorten the intake response delay, making more fully combustion and reducing particulate number and HC emissions in the transient conditions.

Abstract:To analyze and control the errors from the single-pulse laser emitted and the multi-beam detectors parallel received, two-dimensional galvanometer sweeping structure of laser three-dimensional imaging system (LTIS) in Chang’e-3, this paper proposed a novel full-link error analysis and simulation method for multi-channel LTIS in which different aspects are considered, including the ranging link error term of multi-beam range channels (systematic and random) and the angular link error term of the two-dimensional galvanometer. Meanwhile, the error decomposition and simulation procedures of systematic/random error parameter items in the full-link LTIS are conducted to satisfy the accuracy requirement of 20 cm for hazard detection and avoidance in Chang’E-3. The experimental results show that errors in the fixed delay, galvanometer encoder, collimation axis and in horizontal axis have the greatest impact on the accuracy of LTIS. Furthermore, different solutions are designed to control these error factors effectively in the proposed manuscript.

Abstract:In this paper, we use Microsoft’s Kinect camera as an RGB-D sensor example, analyze the depth error source based on the time of flight(ToF) principle and the obtained depth data accuracy of different colors and materials. We conclude that the depth measurement error is linear with the square of the distance, as well as the quantitative rule of depth measurement accuracy under different color materials. Besides, we use high-precision light detection and ranging(LiDAR) data as reference to evaluate Kinect modeling accuracy through comparing absolute error and relative error of parameters between these two models, and improve the Hausdorff distance method to analyze the overall modeling accuracy. Finally, we show both qualitative and quantitative results relating to the actual accuracy of Kinect depth measurement and modeling and its application scope in close range photogrammetry and indoor modeling.

Abstract:International buyers are often faced with supplier selection and relationship management issues. Based on fuzzy mathematics method and quality function deployment (QFD), this study transforms customer linguistic requirements into the criteria of supplier selection. The ordered 26 criteria combined with the dynamic timeline is the systematic and dynamic criteria for supplier selection. Through the analysis of the interaction process, the modes of relationship in cooperation between international buyers and suppliers are categorized into three types including growth, continuation, and recession. International buyers to select suppliers and enhance the level of supplier relationship management.

Abstract:Using the samples of listed companies of science and technology service industry from 2009 to 2014, we empirically study the influence of government subsidies in different life-cycle stage decided by cash-flow method to firm value. We have found that: the scale of government subsidy shows a decreasing trend in the evolution of the corporate life-cycle; In the mature stage and decline stage of S&T service enterprises there are subsidies over and the problem of insufficient subsidies. Therefore, we recommend respectively lowering and improving the scale of subsidies to those companies to optimize the efficiency of resource allocation the subsidies, and thus to promote the development of S&T service industry.