Abstract:To explore the mechanism of the speed perception of the driver， a driving simulation experiment was designed to collect the perceived speed and actual driving speed of the driver，which analyzes the influencing factors such as the geometric alignment of the underground expressway and the side wall change frequency on the speed perception sensitivity of the driver. The prediction model of the speed perception bias sensitivity threshold of the driver was constructed based on the constant speed theory and the machine learning method. The results show that at the 0.05 significant level， there are substantial differences in the speed perception sensitivity threshold of the driver at different speeds ， linear combinations， and sidewall change frequency groups. The Lasso variable filters the characteristic variables according to the short-term， mid-long-term， and long-term time windows. The determination coefficient R2 of the constructed multivariate nonlinear model is 0.645， the determination coefficient R2 of the multilayer perceptron model is 0.727， and the determination coefficient R2 of the support vector regression model is 0.853.

Abstract:Taking the fully welded dimples plate air preheater as the object， the Workbench Fluent software is used to numerically simulate the influence of the characteristic structure parameters of the dimpled plate on the heat transfer and flow resistance performance by orthogonal experiment. Based on the parameter sensitivity analysis， the effect of single factor on the heat transfer flow resistance performance is obtained： longitudinal spacing of dimpled > long axis > horizontal spacing > depth. Moreover， the fact is obtained that under the synergistic effect of multiple factors， the structural parameters horizontal and longitudinal distance have a greater impact on performance than the depth-diameter ratio of the dimpled based on the analysis of the response surface method. Furthermore， three sets of better structural combinations within a given range are obtained based on the genetic algorithm， with the smallest friction factor， and the largest Nusselt number and comprehensive heat transfer factor as the optimization objectives.

Abstract:The directed relation graph with error propagation （DRGEP）， full species sensitivity analysis （FSSA） and directed relation graph with path flux analysis （DRGPFA） were used to reduce the mechanism of methanol. Based on the reduced mechanism， the key primitive reactions were found by sensitivity analysis， then their pre-exponential factors were adjusted by coarse perturbation and refinement perturbation analysis which were on this basis of pre-factor perturbation method， to obtain the optimal optimization mechanism and verify it. The results show that the FSSA reduced mechanism has 16 species and 65 reactions， which can accurately predict ignition delay time and laminar flame velocity. The prediction accuracy of the V6-3-4 optimized mechanism is better than that of the FSSA reduced mechanism， and the predicted value is much closer to the experimental value than the detailed mechanism.

Abstract:The overall stability is the essential requirement of the structural design of super-tall buildings. A single driven constraint optimization design method based on the sensitivity of the stiffness-weight ratio was proposed to control the P-Δ effect (additional effect of gravity caused by horizontal deformation of structure) of super-tall buildings. Stiffness-weight ratio, the ratio of stiffness to gravity load, is an important parameter that affects the P-Δ effect. Based on the principle of virtual work and the method of equal increment analysis, the formulas of sensitivity coefficients were deduced, and the sensitivity coefficients of a two-story plane frame were calculated as an example. The feasibility of the proposed method was verified theoretically. Finally, the proposed method was applied to a super-tall building with a building height of 468 meters. And after adjusting the dimensions of components, a total cost of 9.391 million yuan was saved. The feasibility of the proposed method was illustrated by this engineering case. The results show that the proposed method can reasonably distribute the materials to different component groups for a super-tall building structure with the stiffness-weight ratio as a driven constraint, which can realize the economical and practical structural design.

Abstract:The effects of sensor errors on link flow inference in sensor location flowobservability problem are discussed in this paper. By using the equations of traffic flow conservation system and the model of network sensor location problem based on turning ratios at intersections, a general sensitivity analysis method is proposed to analyze the impact of sensor errors on the link flow reckoning. Firstly, the key factor is defined to represent the errors of link inferring caused by the sensor errors. Then, the total effect of multiple sensor errors on the link flow inferring is proved theoretically to be the linear superposition of the effects of single sensor error. Finally, a square road network is used to test the proposed method. Two sensor location schemes of installing sensors on the only entrance links or exit links of the road network respectively are adopted, which can both support the unique link flow inferring results. The effect of sensor errors on link flow inferring is given by using the key factor method.

Abstract:The MooneyRivlin hyperelastic model and the Prony series viscoelastic constitutive model were used to verify the selected calculation parameters by finite element analysis compared with stress relaxation test data. Then, the AnsysPDS module was used to analyze the sensitivity values of all random parameters to surface contact stress and the influence of hyperelastic and viscoelastic parameters on the surface contact stress relaxation. The results show that parameter values are reasonable. Random parameters which have great influence on the surface contact stress are α2 and C10, followed by α1、τ1 and C01, and the effect of τ2 is negligible. Relaxation mainly occurred on the first day of loading and remained basically stable within 1 year. The larger the values of hyperelastic parameters, the smaller the stress attenuation is, and the opposite of viscoelastic parameters.

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: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: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:In order to study the influence of random material and geometrical parameters of rubber gasket caused by machining error on waterproof performance of shield tunnels lining joint, material hardness, coordinates of the bore center and diameter are selected as the random input variables, targeting the surface average contact pressures of gasket, to calculate the sensitivity values to contact pressures of all these random parameters by using the ANSYS PDS module. The results from an analysis of elastic gaskets used in a certain city metro shield tunnel show that rubber mechanic parameters are principal factors, especially C10. Among geometric parameters, there is more influence on down surface contact stress because of the variation of upper bores diameter in the section. However, positions of bore are sensitive to near surface contact stresses, and the variation of middle bores have almost the same influences on both surfaces.