Abstract:The unsaturated soil was conceptualized as three-phase medium, which consists of fluid, solid and gas, and the shield tunnel was simplified as an infinite Flügge cylindrical shell. The Helmholtz decomposition theorem was used to solve the governing equations of unsaturated soil and the separation-of-variable method was used to solve the motion equations of the Flügge shell. Based on the continuity boundary conditions of displacement and stress, a semi-analytical model for calculating the dynamic response of a tunnel buried in an unsaturated full-space was proposed. The dynamic response of the soil-tunnel system and the effect of saturation on the dynamic response were analyzed. The results show that the soil saturation has a great effect on the magnitude of soil displacement, soil stress, excess pore water pressure and critical velocity. Therefore, it is necessary to take the effect of saturation into account when calculating the dynamic response.

Abstract:By taking double-line concrete simply supported box girder of rail transit as the research object, a vehicle-track-box girder finite element model and a box girder structure-borne vibration-radiation noise finite element model-infinite element model were established. Combined with field tests, the sound pressure distribution of whole box girder and each plate was obtained by the model, and the sound pressure contribution of each plate was analyzed. The results show that the finite element-infinite element model can accurately predict box girder structure-borne noise. The contribution to the sound field of web plate is less. The sound pressure of the near field is mainly affected by bottom plate, followed by wing plate. The sound pressure of the far field is mainly affected by bottom plate and top plate. In the space below bottom plate, the noise radiated by bottom plate dominates the sound field. At the same height of the box girder, the sound pressure contribution of roof plate is slightly larger than wing plate, and these two plates play a major role. In the area above roof plate, the sound pressure contribution of roof plate is much larger than other plates.

Abstract:The fire behavior of one plane and one spatial beam-column concrete joints was investigated under the fire according to the standard ISO834 temperature time curve, and then four specimens (the two fire-damaged specimens, two comparison specimens under room temperature) were tested under low cycle reciprocating loadings. Thus their post-fire residual seismic performances were studied. Furthermore, the cracks, failure modes, hysteretic loops, envelope curves, load bearing capacity, ductility coefficient, stiffness degradation, and energy dissipation were studied and compared in detail. The experimental results show that shear failure happens only in the joint zone of the fire-damaged plane beam-column joint, and the rest three specimens exhibit bending failure in beam ends. It is also demonstrated that the load bearing capacity, ductility coefficient and energy dissipation of the specimens is reduced, and the deformation is increased, after exposure to fire. However, the contribution of slab and orthogonal beams is weakened due to the damage of concrete after fire, which results in a more significant change in the performance of the space beam-column joint specimens before and after fire exposure.

Abstract:Based on the monitoring extreme stress time series data with trend and randomness, the Bayesian dynamic coupled linear prediction for bridge extreme stresses is studied in this paper. Firstly, with the decoupled historical extreme stress data, the dynamic coupled linear model(DCLM) and the corresponding finite dynamic linear models(DLMs） are respectively built. Then, based on the dynamic monitoring decoupled extreme stress data, the probability recursive processes of the built dynamic coupled linear model are proposed with Bayesian method, which can be used to dynamically predict bridge decoupled extreme stresses. Further, the sums of the predicted decoupled extreme stresses can be considered as the predicted results of the bridge extreme stresses. Finally, based on the monitoring extreme stress data with trend and randomness from an existing bridge, the feasibility and application of the proposed method is verified through comparing with auto-regressive integrated moving average (ARIMA) model.

Abstract:An accurate cutting length calculation method for space-warped closure segment which considers the erection deviation of closure port was proposed. To obtain the optimization model drived by the internal penalty function method and calculate the ridge line cutting length of closure segment accurately, an objective function with distance between the characteristic points of closure port and the ridge lines of closure segment was constructed, and the constraints of the erection deviation of the closure segment were satisfied. The closure time was determined by the correlation analysis of the temperature field and deformation with 72 h measured data. The temperature influence correction method of the cutting length was proposed based on weather forecast and the correlation analysis on temperature field and ambient temperature. The steel pylon closure with zero additional stress and high precise came into fact due to closure segment cutting calculation method based on the coordinates of multi-feature points.

Abstract:Driving simulation software was used to design and implement the simulation experiment of horizontal curve of passenger car expressway. Then, the driving characteristics of horizontal curve were analyzed. It is shown that all horizontal curves with different radii satisfy the consistency of absolute speed change and absolute speed gradient. The starting points and returning points of small-radius curves lag significantly, which are 100 m later than the tangent-to-spiral points and 30 m later than the spiral-to-tangent points, respectively. Additionally, the operation load is mainly affected by curvature variation. Horizontal curves with different turns and radii cause inner and outer lane departures. As the radius decreases, the departures increase and concentrate toward inside of the curve with a more stable lateral position.

Abstract:The temperature field of asphalt pavement with thick asphalt layer (>30 cm) was analyzed. Based on the cumulative effect of air temperature and solar radiation on pavement temperature, a regression analysis was conducted on the measured pavement temperature from four selected test sites and the obtained meteorological data. The prediction models for different sites were determined as a function of depth, average air temperature and total solar radiation. Then, the cause for the difference between the models at each site was analyzed, and the historical mean monthly air temperatures were incorporated into the model. The model can be applied to the pavement temperature prediction in different areas. The results show that the model has high applicability and high accuracy.

Abstract:Based on the Kalker’s three-dimensional elastic bodies rolling contact theory and combined with the wheel-rail non-flat contact geometric relationship, the modified equation of the influence coefficient implemented in the minimum complementary energy equation was presented. Considering the interaction between the normal and the shear effects of wheel-rail non-flat contact, the minimum complementary energy equation was discretized. The solution of the discretized equation was transformed into a nonlinear programming problem with the target of the minimum of the total complementary energy, and the algorithm for solving the problem was proposed. The accuracy of the algorithm was validated with a finite element simulation. Lastly, the wheel-rail non-flat contact characteristics under different worn rail conditions were studied and the results show that, under the conditions of different wears and same lateral displacements, with the wear increasing, the wheel-rail contact occurred in the gauge corner changes from a two-point contact to a conformal contact, the corresponding maximum stress decreases, the contact patch becomes narrow and long, and the contact area increases.

Abstract:The attenuation, delay and susceptibility to interference of suspension sensor was analyzed in the process of signal transmission for middle-low speed maglev train, and the solutions were proposed. Firstly, the equivalent model of signal transmission system was established, the working parameters of main devices were optimized according to the principle of impedance matching, from which the attenuation distortion of signal transmission through long cable can be prevented. Secondly, the maximum delay of sensor signal required by the dynamic response of suspension system was analyzed, comparison experiment based on vibration table was also designed and implemented. Finally, according to the characteristics of electromagnetic environment for the signal transmission, the filter circuit and the measures including shielding and grounding were designed, tests such as radio frequency radiation induced by immunity and pulse group immunity were passed. The results show that the dynamic characteristics of suspension system are not affected by the delay of signal serial communication, and the proposed solutions can realize accurate, timely and reliable signal transmission.

Abstract:By analyzing the station environment impact on passenger evacuation behaviors, the calculation methods of attracting potential energy field for facilities and equipment as well as repulsive potential energy field for events and obstacles were proposed. Then an iterative generation algorithm of potential energy field based on the shortest distance was developed to describe the station environmental structure and the environmental impact mechanism on passenger behaviors. On this basis, a fusion method combining the potential energy field model and the improved social force model was put forward, and a dynamic simulation model for emergency evacuations in metro stations was established. Finally, Unity platform and C# programming technology were used to demonstrate and verify the proposed metood.

Abstract:Decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6 tribromophenoxy) ethane (BTBPE), as novel brominated flame retardants, are liable to accumulate in the environmental matrices due to their persistence and lipophilic characteristics. The distribution characteristics of DBDPE and BTBPE in biological and abiotic environmental matrices are reviewed. DBDPE and BTBPE combine easily with solid phase, therefore, their concentration in soil, sludge and indoor dust is much higher than other environmental media. The distribution characteristics of DBDPE and BTBPE in biological matrices are related with biological species, tissues, organs， etc. Moreover, DBDPE and BTBPE were also found in human breast milk, blood and hair. The production and the use of commercial DBDPE and BTBPE, as well as e-waste recycling activities are their main sources in the environment. It is necessary to further explore the transport and transformation behavior of DBDPE and BTBPE in different environmental matrices, and the molecular mechanism of biological effects.

Abstract:The effects of initial pH, H2O2 dosage, Fe-Beta zeolite dosage, temperature and inorganic salt ion concentration on the decolorization rate of Rhodamine B solution in Fenton-like system and the reuse of the Fe-Beta zeolite were discussed. The results show that for the degradation of 100 mL of 100 mg?L-1 Rhodamine B solution, with the initial pH 3.0, H2O2 dosage 0.4 mL and Fe-Beta zeolite dosage 30 mg, after 2 h reaction at 70 ℃, the degradation rate can reach 95%. The recycling rate was high as the degradation rate remained above 80% after 5 times of reuse. Finally, the catalytic degradation of actual dyeing wastewater was investigated. For 30 mL original solution, with H2O2 dosage 10%（volume ratio） and Fe-Beta zeolite dosage 80 mg, after 2 h reaction at 200 ℃, the decolorization rate can reach 96%.

Abstract:Catalyzed diesel particulate filter(CDPF) samples with 15,25 and 35 g?ft-3 (1 ft = 0.304 8 m) precious metal catalyst loadings were designed to study the effects of precious metal catalyst loading on catalytic activity, degradation resistance and selectivity of CDPF by means of catalytic activity evaluation experiment. The results show that as precious metal catalyst loading increases, fresh CDPF samples present decreasing activity on CO and NO2, and show increasing first and then decreasing trend for the oxidation activity of C3H8. Compared with the fresh samples,as the precious metal catalyst loading increases, the aging CDPF samples have stronger degradation resistance performance on CO and NO2. The CDPF coated medium precious metal catalyst loading has better activity and degradation resistance performance on C3H8. Fresh CDPF samples present strong selectivity on CO,while aging CDPF samples have worse selectivity at low temperature than that at medium and high temperature.

Abstract:In order to handle the problem of insufficient braking force produced by the maglev linear eddy current braking device, we corrected specific parameters in electromagnetic field, such as the exciting current, air gap, yoke thickness, core width and polar pitch. The pulse-current was used as the exciting form to increase magnetic field intensity, which can keep a high-speed field shape. By analyzing the deformation of the moving electromagnetic field, the braking force of the braking device is effectively improved. The results show that within a certain range, increasing the pulse amplitude can effectively improve the braking force. On the other hand, as the amplitude of the high pulse level increases, the braking force will greatly decrease. Besides, the pulse frequency has a relatively small impact on braking force. Meanwhile, the higher duty-cycle of pulse can also be used to generate greater braking force.

Abstract:Combining an advanced signal detection technology and active inertial components, the method of on-line detection and control for low-frequency swaying of high-speed train was proposed. The empirical mode decomposition(EMD) and the Hilbert transform were used to extract the feature of the measured swaying signal, and the spectral energy ratio was defined as a detection index. Moreover, the lateral dynamic model of railway vehicles was established with the active inertial control strategy for carbody. The results show that, the spectral energy ratio of acceleration differs by 55% between the non- and swaying segment, with strong discrimination to the swaying signal. Compared with the traditional suspension, the active inertia control strategy reduces the frequency response of carbody at specific frequency band significantly and the corresponding root-mean-square in time-domain simulation reduces by 53%.

Abstract:In this paper, a kinematic precise point positioning（PPP) model of BeiDou System(BDS)/GPS using zone corrections is proposed. Fifteen MGEX（multi-GNSS experiment） stations are selected as reference stations or evaluation stations. Then,the accuracy and the convergence of kinematic precise point positioning of BDS/GPS are analyzed based on 20-day data. Results show that BDS dual-frequency kinematic precise point positioning converges to 1 m in 13 min on average and the coordinate accuracy reaches 0.15 m in horizontal and 0.30 m in vertical component after convergence. The BDS/GPS dual-frequency kinematic precise point positioning shows better accuracy and shorter converge time, which converges to 1 m in 3 min on average and the coordinate accuracy is less than 0.07 m and 0.15 m in horizontal and vertical component, respectively.

Abstract:This paper presents a dense semantic labeling algorithm based on deep learning. Firstly, low-altitude remote sensing data are acquired and preprocessed,and a data set for deep learning is built. Secondly, a fully convolutional neural network is designed and trained on the data set. Finally, the trained neural network is used to predict water quality level for each pixel in the remote sensing images. The algorithm is verified on image data acquired by unmanned areial vehicle（UAV） through low-altitude remote sensing in Jiading District and Baoshan District, Shanghai. Average classification accuracy achieves 87.96% and 77.57%, respectively.

Abstract:A supplier evaluation and selection model of facility management (FM) based on directed weighted network was proposed. Based on the hierarchical treatment of facility management suppliers, the multi-level supplier evaluation index system and the enterprise cooperation degree evaluation index system were clarified, and were used to evaluate the facility management supplier network point rights and border rights respectively. The fuzzy comprehensive evaluation method based on analytic hierarchy process (AHP) was used to assign the directed weighted network point weight and edge weight of facility management suppliers, then a multi-level facility management supplier selection model was constructed, and the shortest path method was adopted to solve the model. Finally, a case simulation was analyzed to illustrate the practicability and operability of the proposed model.