浅谈波速测试在实际工程中的应用

简单的介绍了渡动原理和波速测试方法。应用等效剪切波速对实际工程的建筑场地类别进行判定，对岩层完整性进行了评价以及得到了一些岩层的动参数值为岩石特性的研究提供参考价值。

DETERMINATION OF MATERIAL PARAMETERS FOR COMPUTER SIMULATION OF SUPERPLASTIC FORMING PROCESSES

In order to analyze and simulate the complex super-plastic forming process by computer, a method of equal height bulging for determining material parameters m and K of the superplastic alloy is presented. The formulae related to the method are deduced in this paper. The accuracy of the method is available for evaluating the examples used in simulating the superplastic sheet-metal bulging processes.

Influence of gas pressure state on the motion parameters of coal-gas flow in the outburst hole

Carried on the one-dimensional analysis to the motion state of coal-gas flow in the outburst hole, and deduced the relational expression between the motion parameters （containing of velocity, flow rate and density etc.） of bursting coal-gas flow and gas pressure in the hole, then pointed out the critical state change of coal-gas flow under different pressure conditions which had the very tremendous influence on both stability and destructiveness of the entire coal and gas outburst system. The mathematical processing and results of one-dimensional flow under the perfect condition are simple and explicit in this paper, which has the certain practical significance.

Finite Element Numerical Simulation of Ground Subsidence in Liangjia Colliery

Being aimed at the ground subsidence due to underground coal mining,a numerical model of rock was established and an appropriate method of numerical simulation was put forward.Using the measured subsidence data on the ground,the equivalent mechanical parameters of the rock stratums can be back-calculated by the properly treatment of coal excavation area,then the ground subsidence of other coal mining area can be predicted by FFM.It provided reference for the treatment of the buildings on the ground of this colliery.

Deformation features and failure mechanism of steep rock slope under the mining activities and rainfall

Underground mining activities and rainfall have potential important influence on the initiation and reactivation of the slope deformations,especially on the steep rock slope. In this paper,using the discrete element method(UDEC),numerical simulation was carried out to investigate deformation features and the failure mechanism of the steep rock slope under mining activities and rainfall. A steep rock slope numerical model was created based on a case study at the Wulong area in Chongqing city,China. Mechanical parameters of the rock mass have been determined by situ measurements and laboratory measurements. A preliminary site monitoring system has been realized,aiming at getting structure movements and stresses of unstablerock masses at the most significant discontinuities. According to the numerical model calibrated based on the monitoring data,four types of operation conditions are designed to reveal the effect of mining excavation and extreme rainfall on the deformation of the steep rock slope.

A Compound Algorithm of Denoising Using Second-Order and Fourth-Order Partial Differential Equations

In this paper, we propose a compound algorithm for the image restoration. The algorithm is a convex combination of the ROF model and the LLT model with a parameter function 0. The numerical experiments demonstrate that our compound algorithm is efficient and preserves the main advantages of the two models. In particular, the errors of the compound algorithm in L2 norm between the exact images and corresponding restored images are the smallest among the three models. For images with strong noises, the restored images of the compound algorithm are the best in the corresponding restored images. The proposed algorithm combines the fixed point method, an improved AMG method and the Krylov acceleration. It is found that the combination of these methods is efficient and robust in the image restoration.

NUMERICAL SIMULATION FOR DYNAMIC INITIAL SHOCK PARAMETERS OF COUPLING CHARGE ON BOREHOLE WALL UNDER THE ACTION OF HIGH EXPLOSIVES

According to detonation theory and hydrodynamic principle, a physical model has been set up in this paper. Based on the model a methodology for calculating dynamic initial shock parameters such as shock pressure pm shock wave velosity Dm etc. of coupling charge on borehole wall has ben developed. The shock parameters have been calculated when high explosives works on granite, limestone and marble respectively. The magnitude of every parameter on borehole wall has been obtained from ignited dot to the end of borehole along axial direction. Some important conclusions are also gained.

Numerical method for estimation of kinematical parameters for articulated rovers on loose rough terrain

Based on the study of passive articulated rover,a complete suspension kinematics model from wheel to inertial reference frame is presented,which uses D-H method of manipulator and presentation with Euler angle of pitch,roll and yaw.An improved contact model is adopted aimed at the loose and rough lunar terrain.Using this kinematics model and numerical continuous and discrete Newton's method with iterative factor,the numerical method for estimation of kinematical parameters of articulated rovers on loose and rough terrain is constructed.To demonstrate this numerical method,an example of two torsion bar rocker-bogie lunar rover with eight wheels is presented.Simulation results show that the numerical method for estimation of kinematical parameters of articulated rovers based on improved contact model can improve the precision of kinematical estimation on loose and rough terrain and decrease errors caused by contact models established based on general hypothesis.

Quantitative analysis of influence of α-Al(MnFeCr)Si dispersoids on hot deformation and microstructural evolution of Al-Mg-Si alloys

The microstructural evolution of AA6061 and Mn-bearing Al-Mg-Si-Cu alloys was studied by compression tests that were carried out between 300 and 500 °C with a wide range of strain rates. Compared to the AA6061 alloy, the large amount of α-Al(MnFeCr)Si dispersoids in the Mn-bearing alloy yielded a significant increase in the flow stress under all deformation conditions. The effects of the deformation parameters on the evolution of the microstructure were studied using electronic backscatter diffraction measurements. The predominant softening mechanism of both alloys was dynamic recovery. The presence of α dispersoids in Mn-bearing alloys effectively refined the size of substructures with misorientation angles in the range of 2°-5°, which retarded the dynamic recovery. To predict the subgrain size under various deformation conditions, the threshold stresses that were caused by α dispersoids were calculated by the modified Orowan equation and incorporated into a conventional constitutive equation. The subgrain size that was predicted by the modified constitutive equation showed satisfactory agreement with the experimental measurements.

The Relationship Among Bedrock Seismic Ground Motion Parameters with Different Exceedance Probabilities in the Panxi Area

Based on the calculation of the bedrock effective peak acceleration (EPA) zoning map in the Panxi area, the ratios of EPA with exceedance probabilities of 63%, 5%, 3%, 2% and 1% over 50 years to that of 10% in 50 years are 0.302, 1.30, 1.55, 1.76 and 2.14, respectively. The seismic effect will be conservative and safe if taking this zoning map as the earthquake resistant fortification level and following the relevant rules of the Code for Seismic Design of Buildings (GBJ11 89) to calculate the seismic effect. Furthermore, the main factors that influence the A10/A63 ratios have been found to be the attenuation relationship of seismic ground motion, the division of seismic potential source regions and the seismicity parameters. These achievements are helpful to the spreading and applying of the zoning map.

Water Wave Focusing Using Coordinate Transformation

In this paper, wave focusing based on a coordinate transformation is proposed. It is known that the 2-dimensional wave equation which governs a shallow water problem in a potential theory can keep invariance under coordinate transformation. Once equivalent medium parameters are obtained so as to keep the invariance, wave rays can be arbitrarily designed. We show the design of equivalent medium for wave squeezing to focus waves on a specific domain. Numerical computations are carried out by a finite element based software COMSOL Multiphysics. Results show good agreement between predictions from the theory and computations. It can be applied for a wide range of frequency because the proposed method is able to be applied regardless of the frequency.

Extremes of Shepp statistics for fractional Brownian motion

Define the incremental fractional Brownian field with parameter H ∈ （0, 1） by ZH（τ, s） = BH（s-＋τ） - BH（S）, where BH（s） is a fractional Brownian motion with Hurst parameter H ∈ （0, 1）. We firstly derive the exact tail asymptoties for the maximum MH＊（T） = max（τ,s）∈[a,b]×[0,T] ZH（τ, s）/τH of the standardised fractional Brownian motion field, with any fixed 0 〈 a 〈 b 〈 ∞ and T 〉 0; and we, furthermore, extend the obtained result to the ease that T is a positive random variable independent of {BH（s）, s ≥ 0}. As a by-product, we obtain the Gumbel limit law for MH＊r（T） as T →∞.

A moving average Cholesky factor model in joint mean-covariance modeling for longitudinal data

Modeling the mean and covariance simultaneously is a common strategy to efficiently estimate the mean parameters when applying generalized estimating equation techniques to longitudinal data. In this article, using generalized estimation equation techniques, we propose a new kind of regression models for parameterizing covariance structures. Using a novel Cholesky factor, the entries in this decomposition have moving average and log innovation interpretation and are modeled as the regression coefficients in both the mean and the linear functions of covariates. The resulting estimators for eovarianee are shown to be consistent and asymptotically normally distributed. Simulation studies and a real data analysis show that the proposed approach yields highly efficient estimators for the parameters in the mean, and provides parsimonious estimation for the covariance structure.

The determination of thermal junction potential difference

A novel method has been designed and exploited to determine the thermal junction potential difference(TJPD) between two acids or alkalies of the same composition but with different temperature. The absolute value of measured TJPD between two strong acids(or alkalies) maintained at different temperatures increases with increasing of the temperature difference between the two electrolytes over the range from 0 to 40 °C. In strong acids, the hot end always has the lower potential while in strong alkalies, the cold end has the lower potential. This is because the ions of fast diffusion rate contribute most to the TJPD. Our results demonstrate the importance of the correction for TJPD in deriving the kinetic parameters when studying the temperature effect on reaction kinetics.

Modeling of delta-wing type vortex generators

A numerical model of delta-wing type vortex generator was developed in two steps.The first step was to obtain a parameterized model of the shedding vortex based on delta-wing theory,which relates the geometry parameters and flow field parameters to the strength of shedding vortex which directly decides the source term.In the second step,a method was proposed to add source terms into the flow control equations so that the shedding vortex could be simulated numerically.As soon as the numerical model was completed,two cases:One for a plate and another for an airfoil segment were investigated for test.Comparison showed that the flow field structure and aerodynamic performance agreed well with those obtained from cases with real vortex generators.