Gongcheng Kexue Yu Jishu/Advanced Engineering Science

The seismic effect created by blasting operations vibrates adjacent buildings and disturbs residents living in these buildings, often leading to disputes and complaints. In this paper, the vibration acceleration was calculated based on the measured blasting vibration velocity using the wavelet denoising-based four-point forward difference method. The infinite impulse response (IIR) digital filter was used to obtain the frequency weighting of acceleration, so as to calculate comfort assessment indexes such as vibration dose value (VDV), maximum weighted vibration severity (KBFmax and annoyance rate. Combined with the survey of engineering cases, comparative analysis was conducted on the indexes and standards that were suitable for the comfort assessment of blasting vibration. The results indicated that VDV, KBFmax, and annoyance rate indexes could all reflect the impact of blasting vibration on comfort to a certain extent, and that while the first two indexes could only be used for qualitative assessment, the annoyance rate index could be used for quantitative comfort assessment. In addition, by applying these assessment indexes for the comfort assessment of blasting vibration, preliminary control standards were provided.

A coupled dynamic model, which contains helical gears-shafts-bearings for a wind turbine gearbox transmission system, was built considering nonlinear factors of the time-varying mesh stiffness, the external varying load, and the dynamic transmission error at first. The model is confirmed to be right after comparing the theoretical data with the experimental load sharing values, and also it is found that the static load sharing is conservative to evaluate the non-equilibrium effect of a planetary gear system. Besides, the analyzing results of the influence of average error and amplitude error on the load sharing show that the load sharing could be decreased if the error goes up a little. Then, by means of treating the static tracing point as the dynamic initial values, we analyzed the initial position’s influence on the load sharing of transmission system to provide a theoretical basis of load sharing control. Furthermore, we explored the influence of high-speed shaft position angle on the load sharing and the dynamic load factor of gears fixed on the parallel shafts. The results provide useful theoretical guidelines for the design of parallel shaft gear system in the wind turbines.

In order to solve the modeling problems of saturated porous media, the engineering mixture theory was used to formulate the bulk constitutive theoretical framework of saturated porous media. Firstly, Supposing that the bulk deformation works of porous solid and fluid matrix were mutually independent and using Terzaghi’s effective spherical stress and pore pressure and fluid matrix pressure as stress state variables of constitutive model, the bulk stains expressions of solid phase and solid matrix and fluid matrix were obtained in the complementary energy.Secondly, the solid and fluid bulk constitutive equations of saturated porous cubes of balsawood in the loading and unloading stages were founded on the basis of the measuring data of model test conducted by Lade and de Boer. The calculating formulae of mechanical parameters were deduced such as solid bulk tangent modulus, Biot’s tangent coefficient and fluid Biot’s tangent modulus and so on. The change rules of mechanical parameters along with Terzaghi’s effective spherical stress and pore pressure were analyzed in the loading stage for solid bulk tangent modulus,Biot’s tangent coefficient and fluid Biot’s tangent modulus and so on. Finally, the one-dimensional consolidation equation of saturated porous media was derived from the bulk constitutive models of the paper and static balance equation. The consolidation behaviors of saturated porous cubes of balsawood were numerically analyzed and the change curves of consolidation degree and settlement with time were obtained. The researches show that, the solid bulk tangent modulus increased along with Terzaghi’s effective spherical stress and decreased along with pore pressure. The Biot’s tangent coefficient was between 0.42～0.95 and decreased along with Terzaghi’s effective spherical stress and pore pressure. The fluid Biot’s tangent modulus decreased firstly and then increased with Terzaghi’s effective spherical stress, and decreased with the increase of pore pressure. The tangent coefficient of pore pressure was less than 1.0 in most cases. The initial pore pressure was not equal to the external load in saturated porous media considering the compressibility of solid matrix. Thus the immediate settlement exists in saturated porous media after external load was applied. The modeling method in the paper can be used to model and numerically analyze nonlinear saturated porous media.

Apache Spark is a distributed open source framework for big data processing. The performance of Spark is greatly affected by parameter configuration settings. To get the best performance from Spark is still a big challenge because of a large number of parameters. This parameter is tuned manually by experimentation which is not effective. Besides, these parameters must be re-tuned for various applications. In this work, a method based on machine learning is proposed and developed to effectively self-tune Spark parameters. The results show that the performance is speeded up by 33.4% on an average, compared to the default configuration.

With the increasing contradiction between water supply and demand in large-scale irrigation areas in Northwest China, food production security has gradually become a major threat. The traditional optimized canal water distribution model is mainly based on the objective function to optimize the crop water demand configuration, and the objective function parameters and constraints are more complicated. It is difficult to achieve global optimization of water distribution. This paper takes the Xidong canal system in the Xijun Irrigation District of the Heihe River Basin as an example, adopts the principle of “constant flow, controlled opening”, and establishes a backtracking search algorithm to optimize the water distribution equation based on the principle of minimum remaining flow under the condition of a constant flow of the main canal design. Channel valve opening and closing water distribution time diagram, and further obtain the valve control time point skewness coefficient, and compare the obtained results with the vector evaluation genetic algorithm, particle swarm algorithm water distribution time, and valve time control deviation degree, on this basis The adaptability of the model is evaluated in combination with the abandoned water situation of the canal system of Xiaohe Station. The results show that the water distribution time of the backtracking search algorithm, the vector evaluation genetic algorithm, and the particle swarm algorithm are 12.70, 14.38, and 15.50 d, respectively, and the skewness coefficients at the opening time of the valve are 0.093, 0.328, 0.217, which is obvious compared with the water distribution model of the backtracking search algorithm. The time superiority and stability of the backtracking search algorithm is zero in the Xidong canal system where the canal water utilization rate is low, and the water abandonment phenomenon in the canal system of the Xiaohe station with a high canal system water utilization rate is serious, and the algorithm is common It is suitable for areas with low canal water utilization rate. Using the backtracking search algorithm to optimize the water distribution in the irrigation area, under reasonable applicable conditions, not only can ensure the optimal irrigation time and meet the requirements of the canal irrigation system, but also can maintain the relative stability of fluid transportation to achieve the purpose of optimized water distribution in the canal system.