Abstract:The Xin’anjiang model and Support Vector Machine(SVM)model were applied to the real-time flood forecasting of 4 basins in Zhejiang Province and Shaanxi Province. The K-Nearest Neighbor algorithm was used to correct the results of Xin’anjiang model. The forecasting results of different basins with two models were compared and analyzed by the evaluation indices of certainty coefficient, flood peak time error, flood peak relative error and mean square error. Further study was made to analyze the forecasting accuracy of two models in different forecast periods. The results show that Xin’anjiang model and Support Vector Machine model have their own advantages in the real-time flood forecasting of different basins. The accuracy of Support Vector Machine model is more susceptible to the accuracy of precipitation forecasting. Xin’anjiang model performs better in the case of long forecast period. With the forecast period reduced, the accuracy of Support Vector Machine was obviously improved. Meanwhile, Support Vector Machine model has a higher forecasting accuracy in the short forecast period. However, in semi-humid and semi-arid basins where the flood forecasting is difficult, the Xin’anjiang model and Support Vector Machine model have high accuracy in both calibration periods and real-time forecasting processes.

Abstract:In order to study the runoff-erosion process of saline-alkali silty loam slopes in a coastal reclamation area, a series of runoff scouring experiments were conducted to investigate the effects of slope gradient and upstream inflow on the soil detachment process. The results showed that the slope gradient and upstream inflow both had positive effects on the detachment rate but their effects were mutually restricted. The relationships between soil detachment rate, inflow scouring rate and slope gradient can be expressed by a power exponential function. The runoff energy consumption of unit width increased significantly with the increasing of upstream inflow rate and slope gradient(P < 0. 01). In addition, the relationships between the runoff energy consumption of unit width e_w, upstream inflow rate q and slope gradient θ can also be expressed by the power exponential function. The critical runoff energy consumption of unit width was 15~40 J/(h·m)for slopes between 5° and 15°, while it was zero for slopes between 20° and 40°. There was significant linear relationship between the soil detachment rate and the runoff energy consumption of unit width and the relationship can be expressed by the following function: R²=0. 82. Soil detachment started when the runoff energy consumption of unit width was very small for saline-alkali soil slopes in the coastal reclamation area.

Abstract:The properties of organic matter in raw water were explored to identify the precursors of dichloroacetonitrile(DCAN). In addition, the removal efficiency of DCAN formation potential in the drinking water treating process of an advanced waterworks around Taihu Lake was also investigated. Results show that hydrophilic organic matter and organic matter with molecular weight <1 kDa or >10 kDa were main precursors of DCAN. The removal efficiency of DCAN precursors by the advanced water treating plant was as high as 79. 3% and the contribution rates of O₃/BAC was much higher than the conventional process.

Abstract:For the underground tunnel, current stability analysis methods usually have such limitations as being empirical as well as having discrepancy in evaluation criteria. In order to calculate the stability of underground tunnels with unified models and evaluation criteria, the concept of acceleration calculation is introduced into the stability analysis of underground tunnels, and a tunnel stability analysis method based on it has been put forward. Example shows that the calculated results of acceleration have the same trend with those of the point safety factor, and the proposed method is more suitable to reflect the overall stability of tunnel surrounding rock than the point safety factor. Additionally, by drawing the contour of acceleration and acceleration factor, the stability of surrounding rock and its spatial distribution characteristics can be plainly illustrated. This explicit method can be easily achieved with a uniform mode and an evaluation criterion both for tunnel and slope, so as to solve the problem of tunnel stability evaluation which is usually difficult to be handled by traditional methods.

Abstract:In order to overcome the limitations of traditional methods, an intelligent compaction(IC)technology-based method for the real-time monitoring of compaction quality of highway asphalt pavements as well as the rapid assessment was proposed using the combined index of the frequency analysis index and the unit volume compaction power(E). It could realize the rapid assessment of compaction quality for highway asphalt layers with the 100% coverage of construction zone and effectively overcome the shortage that the value of C_V0 was easily influenced by the hardness of subgrade(lime-fly ash layer and water stable layer). Accordingly, the estimated compactness error was decreased, resulting in a high detecting precision of asphalt layers compaction quality. The presented method is helpful to improve the construction quality and provides a new way to control the construction quality of highway.

Abstract:Based on the constitutive theory of statistical damage and the assumption that the shear strength of anchor bar’s interface element obeys the Weibull probability distribution, a statistical damage constitutive model considering the residual strength for anchor bar’s interface was established. A small segment of the anchor bar was selected to analyze the force balance, and then, the numerical solution of the shear slip, axial force, side resistance and damage of anchor bar was obtained. Based on an indoor pullout test, the constitutive equation was determined and verified by an engineering example. At the same time, the whole working course for the force transferring of anchor bar was studied as well. Results indicate that with the pulling force increases, the side resistance at the top of anchor bar increases to a peak value and then decays. Finally, it reaches the residual strength remaining unchanged and the shear stress distribution curve is further transferred to the deeper. The essence of the interfacial stress softening is the process of damage’s accumulation and transferring. The parameter m can reflect the softening velocity of shear strength afterpeak value. Thus, decreasing the value of m can reduce the rate of stress softening as well as damage accumulation and transmission, thereby reducing the degradation rate of the overall stiffness of anchor bar and the anchor bar’s displacement in a certain load range.

Abstract:The recommended designing method in the codes of CFG pile composite foundation for storage tanks is based on the bearing capacity controlling. It has been pointed out that this design method does not consider the actual bearing capacity of soil between piles and that of CFG piles. According to the deformation and stress behaviors of soil between piles and CFG piles in the composite foundation, as well as the characteristic of storage tank foundation, a new settlement controlling design method has been brought forward for the CFG pile composite foundation of storage tanks. According to the relationship of composite foundation settlement, different reinforcing depths and different replacement rates, as well as the allowable settlement value of foundation, an economical and feasible technical plan is determined and the bearing capacity of composite foundation is also checked, achieving a optimal design. The proposed method has been proved to be economical and feasible to the application in practical projects.

Abstract:With respect to the property of static boundary value problem of solids, a smooth particle static(SPS)method is developed based on the particle discretization of spatial domain. To increase the accuracy of numerical method and maintain the amount of calculation, the governing equations are established through the application of principle of minimum potential energy, rather than using the strong form of equilibrium equation. The approach avoids the use of second-order derivatives of displacement and reduces related errors. An alternative integration method over the supportive domain is proposed which allows a direct treatment of boundary condition without virtual particles along boundary. Numerical examples are presented to demonstrate the good performance of the proposed method.

Abstract:Aiming at the discontinuity of hard crust outside the toe of embankment(such as fishpond, etc. ), through theoretical analysis and numerical simulation, the failure mode of a soft soil layered foundation with continuous and discontinuous hard crust has been compared and analyzed under the embankment load, and a judgment parameter of failure mode, namely the critical distance L_cr, is proposed to distinguish between the general shear failure mode and the local shear failure mode. With the principle of orthogonal test, factors that influence L_cr have been analyzed, and each factor is given in order of sensitivity. Then, using the iterative method with stepwise regression, mathematical formulas of upper(L_crU)and lower(L_crD)limits of the critical distance are given respectively, and their reliability are demonstrated by checking an engineering project. The results indicate that the failure mode of soft soil foundation with continuous hard crust is general shear failure. When the hard crust layer is discontinuous, the failure mode is general shear failure if the distance between discontinuous section and embankment toe is less than L_crU or higher than L_crD, and local shear failure if the distance is between L_crU and L_crD. The thickness of hard crust layer is the main factor to L_cr and the secondary factor is the thickness of soft soil layer, while the influence caused by the internal friction angle and the cohesion of hard crust layer is smaller.

Abstract:An equivalent linear model for the seismic analysis of the isolated gas duct using thermal sliding double concave friction pendulum(TS-DCFP)system is established. The structure is modeled as a two-degree-of-freedom system in the transverse direction. Meanwhile, the effective stiffness and equivalent viscous damping ratio of an isolation bearing with tri-linear behavior are derived and the modal-combined damping ratio is obtained from the modal potential energy ratio of components. The model is verified by comparing the response of a linear time history analysis of the two-degree-of-freedom system with that from the 3D nonlinear time history analysis using the directly integrating method.

Abstract:Considering the nonlinear and dynamic characteristics of settlement deformation, a global piecewise nonlinear analysis model of settlement deformation is proposed based on the modified M5′-principal component(M5′-PCR)model tree, to analyze the settlement process by selecting the influence factors with correlation analysis and reducing the dimension of high dimensional influence factors with principal component analysis method. The the improved M5′-PCR model tree is verified by comparing with the measured settlement. By comparing the prediction results of improved M5′-PCR model tree, M5′ model tree, multiple linear regression, and principal component regression analysis model through the absolute difference and the root mean square error, the results show that improved M5′-PCR model tree has a higher precision in settlement prediction and provides a new approach for the analysis of dam settlement deformation.

Abstract:In order to study the unsteady pressure and velocity of the inlet region in the outlet conduit for the S-shaped shaft tubular pumping system, the whole flow passage of the pumping system was simulated based on the CFD technology. Comparison of numerical simulation results and experimental values under different operation conditions verifies the accuracy of the numerical model. The results show that, the maximum relative deviation of head coefficient is 3. 15%, and the maximum deviation of efficiency is 3. 07% in the range of simulated operating conditions compared with the experimental data. The distribution of axial velocity is affected by the number of the guide vane blades in the circumferential direction, and the wave trough number of the axial velocity filed in the circumferential direction is the same as the guide vane blade number. With the decrease of flow rate coefficient, the wave peak characteristic of the axial velocity filed is more obvious, and the wake characteristics increases gradually as well. When water flows through the outlet conduit, the pressure will increase and the velocity will decrease gradually. The rotation speed of impeller has little effect on the main frequency of inlet region in the outlet conduit. Both the inlet flowing pattern and flow improvement of guide vane have effects on the pressure fluctuation. The main and secondary frequency of every monitoring points are low frequency pulsation in different operating conditions.

Abstract:This paper proposes a system of Electric-field Coupled Power Transfer working in the seawater environment. At first, the basic working principle of proposed system is briefly introduced. The electric field coupling is a key part to delivery power in this system, thus this study focus on the calculation of equivalent capacitance of the underwater coupling structure, the distribution of electric field, the influence of transmission distance on it and the power loss. Then, the result is compared with the air coupling structure. Based on this research, there are two important conclusions: (a)The equivalent capacitance of underwater coupling structure is larger than that in the air environment and not affected by the transmission distance; (b)Increasing the operating frequency or the load can reduce the power loss of coupling structure. Finally, the experimental system of electricfield coupled power transfer(ECPT)is designed to verify above conclusions.

Abstract:Cascaded H-bridge rectifier(CHBR)are usually used in the high-voltage situations such as APF(Active Power Filter)and PET(Power Electronic Transformer). Further, the capacitor voltage balancing is an important issue of this topology. Based on the mathematical model of CHBR, a novel PI-based capacitor voltage balancing method is proposed with the carrier phase-shifted SPWM technique. The relationship between the modulation index and the active power of cells is deduced by the mathematical analysis, and the voltage range of proposed capacitor voltage balance control is derived. A three-module CHBR simulation model, as well as an experimental prototype, is built. Experimental results indicate that the presented method has good performance on the capacitor voltage balance.