Abstract:Aimed at the shortcomings of the segmental catenary method, such as poor convergence performance and low computational efficiency, this paper proposes a coordinate system method based on overall mechanical analysis (COM). In this method, the initial cable shape is assumed to be linear and the target cable shape is then calculated by iterations based on the overall equilibriums of forces. This method is used to calculate the cable shape of the Chishui Bay Bridge in Hebei Province by MATLAB, and the results are compared with measured data. The comparison shows that the proposed method has a faster convergence speed and higher accuracy.

Abstract:The strain of connecting reinforcement versus shear load relationship was analyzed, based on an experimental study on double-superimposed shear wall horizontal connections subjected to reversed cyclic shear deformations combined with vertical loads. The results showed that the variation trends of connecting reinforcement strain in double-superimposed shear wall horizontal connections were identical with that in cast-in-place horizontal connections. The shear mechanism of double-superimposed shear wall horizontal connections was analyzed based on shear-friction theory, the ultimate shear capacity of the double-superimposed shear wall horizontal connections was determined by the bond force at the interface, the interface friction and dowel action of shear connecting reinforcement. The proposed calculation formula for shear bearing capacity of the double-superimposed shear wall horizontal connection was derived based on the shear-friction theory.

Abstract:With the rapid development of large outdoor billboards in recent years, their destruction resulted from the strong wind happen occasionally.A billboard is a typical wind- vulnerable high-rise structure with special open plates. The synchronous multi-pressure scanning measurement was conducted to the rigid model of a typical three-plate billboard. The statistical characteristics of net pressure distribution on the plates in different wind directions were comprehensively analyzed. Moreover,the envelop of the maximum positive and negative value of wind pressure in all wind directions are supplied and simplified. Furthermore, the shape factors of wind load distribution on the three plates and their simplified diagrams in most unfavorable wind directions were discussed and given. The change of wind force coefficients of overall three plates in different wind directions was analyzed as well. This paper provides basic data and wind load parameters for the wind resistant design of the plates and the supporting column of three-plate billboards.

Abstract:An analytical module based on the COMSOL Multiphysics software was developed to consider the effects of two-phase flow and convective dispersion. Using chlorobenzen as the material and choosing typical parameter values, the numerical analysis of vertical migration of DNAPL in homogeneous saturated clay was conducted. The convective diffusion analysis shows that the migration speed of the dissolved DNAPL by molecular diffusion is very slow，only about several centimeter per year. The DNAPL - water two-phase flow coupled convective diffusion analysis indicates that for saturated cohesive soil with a larger permeability coefficient (k=1×10-6 cm?s-1), The DNAPL migration velocity caused by the two-phase flow is large, about tens of centimeters per year. The dissolution of liquid DNAPL leads to the concentration of dissolved DNAPL in pore-liquid quickly and achieves solubility. These results suggest that two - phase flow is likely to be the main mechanism for the deep migration of DNAPL in saturated clay observed in some sites.

Abstract:This paper presents a novel approach for construction management and quality control of prefabricated buildings based on building information modeling (BIM) and 3D laser scanning. First, the current prefabricated construction management mode and deficiencies in information applications are analyzed. Next, a prefabricated building BIM platform for construction process management is described by combing its main module framework.After that, a construction quality control method based on laser scanning is also proposed. By combining the BIM management and the quality control using laser scanning, a new digital construction method for prefabricated buildings is presented. Finally, the research results are successfully applied in a practical project, which proves the practicability and feasibility of the proposed method.

Abstract:This paper presents a novel model of lane allocation optimization for signalized isolated intersection,considering different approaches, movements, and lane function use as well as the effect of their interactions. The mathematical model takes into consideration the constraints, including the number of approach lanes, number of exit lanes，flow conservation，lane markings of approach lanes，and equalized degree of saturation. The optimization model aims at the least critical flow factor and the least minimum variance of flow factors for arm. For shared-lanes, constraint equations of equalized degree of saturation are established according to different lane-use patterns. Finally, the optimization model is verified by the actual data of intersections, which lays a theoretical foundation for the development of signal control aided design software.

Abstract:Possible safety-critical events (SCEs) were identified from the naturalistic driving data using a threshold method. Random forests (RF) and support vector machine (SVM) models were employed to further screen the possible events, overcoming the defect of a high false positive rate while applying threshold methods solely. A set of threshold criteria was established and 3 623 possible SCEs were extracted from the naturalistic driving data in Shanghai. The RF method was adopted to select the important features as input variables. The RF and SVM models were trained and tested respectively on the same dataset. The results indicate that:the mean and minimum value of longitudinal acceleration, the minimum value of the distance from the leading vehicle and the standard deviation of the speed of the subject vehicle can effectively determine whether the possible events are valid or not.Compared with RF, SVM performs better in prediction, that is, filtering 85.9% invalid events and controlling false negative rate simultaneously.

Abstract:This paper focuses on the comprehensive travel cost of motorized trips to urban complex, and adopts the scenario analysis method to construct a multinomial logit model to study the impact of changes in the cost of private cars, taxi, time-sharing automobiles, and public transportation on travel behavior. The analysis shows that travelers become increasingly sensitive to out-of-car time than to in-car time, with the mode transferring from “private” to “public”, namely private car–taxi– time-sharing automobile–public transportation. The time-sharing automobile with the encryption of the location, the shortening of outside-car time, the alternative to private car, public transportation, and other means of travel is significant, which cannot reduce the proportion of private car use. At the same time, when the travelling time is shortened, the rental fee is increased, and the time for public transportation is shortened, the proportion of public transport will not be affected. With the development of time-sharing automobile, the strategy for public transport priority should still be pursued.

Abstract:Based on the state space equation of the discrete system with the adaptive notch algorithm, two evaluation indexes of convergence speed and steady-state error are proposed, and the calculation methods of convergence rate and steady-state error gain are deduced. Moreover, the effects of convergence rate, notch frequency, number of channels, secondary path characteristics and reference signal on convergence rate and steady-state error are analyzed. Furthermore, the simulation results are verified by experiments.

Abstract:By means of computational fluid dynamics, this paper studies the effects of body simplification on the aerodynamic drag of a sedan under different rim design conditions. First, the numerical method is verified in a wind tunnel experiment. Then, the grille and wheel housings of the detailed sedan model are sealed while its bottom is flattened. The results show that the drag varies and the flow field around the wheels as well as at the bottom also obviously differs after simplification. Finally, the detailed parts inside the engine bay are simplified while the grille and the detailed bottom are kept. The results show that the drag is also very sensitive to the simplification inside the engine bay. Therefore, great care should be taken in body simplification when optimizing the wheels for lowering the aerodynamic drag of the vehicle.

Abstract:In this paper, a CFD model coupled with detailed chemical mechanism is established based on a common rail diesel engine test platform, the effect of oxygen concentration on diesel engine combustion process is investigated, and the enhancement in thermal efficiency with direct water injection is verified. The calculation results indicate that the in-cylinder specific heat ratio can be improved by increasing oxygen concentration, which results in an elevated in-cylinder pressure and temperature during compression stroke, promotes in-cylinder combustion reactions, enhances in-cylinder turbulence kinetics, and results in an advanced combustion phase. By injecting 160°C high temperature and high pressure water at 5°CA ATDC, the in-cylinder combustion process can be optimized. The injected water absorbs combustion heat and evaporates into steam which further propels the piston during expansion stroke, thus increasing the overall thermal efficiency of the diesel engine by about 3.75%.

Abstract:This paper introduces an aerosol atomization factor to calculate the mass emission rate of oil particles using the maximum fluid flow rate for atomization obtained from a theoretical model. The particle size distribution is obtained by the Rosin-Rammler function. An environmental chamber is used to obtain the mass median diameter and the distribution coefficient of the Rosin-Rammler function, as well as the aerosol atomization factor. The particle emission rate is then modelled for each particle size.The experimental data show that the mass emission rate of oil particles ranges from 14.58 to 620.95 mg?h-1. Both the particle emission rate and the aerosol atomization factor increase with tool rotational velocity. Moreover, the aerosol atomization factor is a linear function of the tool rotational velocity, with a determination coefficient R2 of 0.998. The model established in this paper represents the oil particle emission rate accurately for each particle size, with an average error of 3.69±12.7 mg?h-1.

Abstract:Aimed at the problem of insufficient adhesion during train traction and braking, a novel electromagnetic thickening device mounted on the bogie is proposed based on the principle of electromagnetic action. Around the high-speed rotating wheel,the electromagnetic coil is set, the basic structural model of the electromagnetic thickening device is established,an electromagnetic field between the wheel and the rail is formed, and the variation law of the electromagnetic force between the wheel and the rail with the train speed, and the impact of electromagnetic attraction on the wheel rail adhesion are analyzed. By adjusting the coil height and thickness ratio and the arrangement around the upper and lower spaces of the wheel, the magnetic field strength and the magnetic field line distribution near the wheel-rail contact are strengthened, and the electromagnetically-adhesive device magnetic conductive shell form and the air gap control magnetic circuit are guided and scoped, and the vehicle is considered,taking into consideration the limit and installation conditions to optimize performance and structural parameters. The simulation results show that the electromagnetic thickening device can significantly improve the vertical pressure between the wheel and rail at each speed stage, and can increase the wheel-rail adhesion. At the same time, by adjusting the pressure at both sides of the wheel, the running stability of the train can be improved.

Abstract:A loading system based on electro-hydraulic proportional control is designed. To meet the requirement that the hydraulic loading system of the test machine can linearly control the loading force of the test bridge deck, a loading mechanism is designed, which makes the error on loading force less than 0.2% when the maximum tire deformation occurs. Meanwhile, a simulation model of the loading system is established to simulate and further analyze the dynamic and static characteristics. Finally, the static and dynamic characteristics of the loading system are verified by the static loading experiment and the sinusoidal loading experiment with the same amplitude at different frequencies, respectively. The experimental results show that the loading system can achieve linear loading between the control voltage and the loading force, and satisfy the constant loading within 15 000 kg and under the sinusoidal loading condition when the amplitude is less than 1 500 kg and the frequency is within 2.0 Hz.

Abstract:The joint inversion of direct currency resistivity data and audio magnetotelluric data under the condition of unstructured triangle mesh is studied. A step-by-step inversion technique is developed,and an adoptive mesh refinement method is studied based on the model sensitivity information. The inversion from coarse mesh to fine mesh reduces the dependence on the stabilizer. Least computational cost of searching regularization factors is required compared with traditional regularization method. The model gradient is calculated by using the least square method.Therefore,the minimum structure stabilizer is established based on unstructured triangle mesh. The cost function is optimized by using the Gauss-Newton method, and the Gauss-Newton system is solved by using the bi-conjugate gradient stable method, aiming to reduce the memory requirement and ensure the stability of inversion. Both the synthetic and field data are inverted.The inversion resolutions show that the joint inversion of the two data sets improve resolutions, and reduce the non-uniqueness of the regularization inversion problem. Joint inversion can get shallow anomalous bodies, which can cause static shift of the audio magnetelluric method.

Abstract:A WRF (weather research and forecasting model) / CALMET (California meteorological model) coupled system was used to simulate the near-surface wind field of super typhoon Meranti in 2016. An improved scheme of kinematic effects of terrain for typhoons (KETT) was proposed. The results show that the systematic error of simulated wind fields near the typhoon center can be successfully eliminated by using the KETT scheme. Compared with the original kenematic effects, the root mean squared errors (RMSEs) of 10-m wind speed and wind direction can be reduced by 10.8% and 5.4%, respectively. Besides, both RMSEs of 10-m wind speed and wind direction with the KETT scheme can be reduced by over 12% than those without the kinematic scheme at Shishe Mountain, indicating that the impact of local terrain on the fine-scale typhoon wind structure near the surface can be better expressed by the KETT scheme.

Abstract:To manage the risk of the hmanufacturing execution system（MES） in digital factories under the background of intelligent manufacturing, this paper uses combined weight and grey relational analysis （GRA） to improve the failure mode and effects analysis（FMEA） model, and then constructs the MES risk analysis model. Considering the importance of the risk factors, it combines the subjective analytic hierarchy process and the objective entropy-weight method to assign the relative weights of risk factors, which not only analyzes systematically but also reduces the subjective influence of experts. The FMEA team identifies the potential risks in MES and evaluates them with fuzzy linguistic terms, and then calculate the grey relation degree of the failure modes by the GRA to improve the accuracy of the risk ranking effectively.

Abstract:Based on the WBS(work breakdown structure) in practice, a probability distribution of delayed activity frequency is proposed to depict schedule default risks in different subsystems of airport construction project from an overall and systematic perspective. Considering the lack of schedule default data, Bayesian methods are employed to estimate the distribution parameters. In particular, MCMC (Markov chain Monte Carlo) simulations are applied as computational scheme to obtain Bayesian estimates. The research process shows the way to model schedule default risks for different subsystems of airport construction project. The application of the MCMC method to estimate the parameters shows advantages in robustness according to different choices of distributions. The use of Bayesian methods makes it possible to integrate qualitative information, and constantly update the model during the construction in the future.

Abstract:Because the credit history data of small and micro enterprises are small and the problem of class imbalance is more serious, this paper proposes a Smote XGboost-Bayes Minimum Risk (SXG-BMR) model based on the sample-dependent cost matrix. The whole sample is oversampled at a low rate to weaken the problem of class imbalance and reduce the risk of model overfitting. The model combines the integrated learning model with the minimum risk Bayes decision to realize the cost sensitivity. At the same time, this paper introduces the sample-dependent cost matrix into the model. The cost matrix is related not only to the category, but also to the attributes of the sample.Therefore ,it can characterize the cost more accurately. In the empirical study,this paper uses a standard credit dataset and a real credit dataset of small and micro enterprises in Shanghai. Besides,it compares and analzes of various algorithms. The results show that the SXG-BMR model proposed in this paper has a good performance.