岩体超声波测试探头耦合方法的改进

简述了超声波测试岩体松动圈的方法,通过超声波反射率理论分析了探头耦合的作用机理,讨论了水耦合探头遇到仰孔、吸水膨胀孔、水渗漏严重孔等时存在的问题;对封口注水耦合法、乳膏类耦合法、囊耦合法进行了对比分析,提出了一种三胶囊超声波探头耦合方法,并成功应用于中煤平朔煤业责任有限公司的工程实践中。应用结果表明,该方法简单、方便、易行。     

圆形零件的排样问题

根据某家电制造企业提出的圆形零件排样问题,给出了该企业提供的3种排样方式——并排、品排和品排斜排的模型。然后,对这3种排样方式进行了简单的介绍和分析,并通过对实际数据的计算说明了品排斜排的排样方式要优于并排的排样方式。针对品排斜排的排样方式,又提出多列选择,即在原始的品排斜排方案上去掉“两列一组”的限制,改为多列一组,并利用实验数据,给出品排斜排下各列对应的利用率。通过这些利用率数据发现：品排斜排方式下的利用率随列数的增加呈现一个先升后降的趋势。     

Correlation of Rheological and Microstructural Properties in a Model Lipid System

Model systems having different microstructures and rheological properties were obtained by controlled crystallization from a mixture of high-melting and low-melting lipids. Based on analysis of confocal scanning light microscopic images, the microstructural characteristics of the systems were quantified by use of different approaches including microstructure density, Euler characteristic, nearest-neighbor analysis, fractal dimension of microstructure interface, and fractal dimension by the particle-counting method (PCM). The solid-fat content (SFC) of semisolid lipid samples was measured by nuclear magnetic resonance (NMR) spectroscopy and rheological properties were analyzed by compressive penetration tests with a texture analyzer. As expected, SFC had a major impact on rheological properties, but lipid crystalline microstructure also had significant effects. Correlation analysis showed that rheological properties were highly correlated with the various quantitative microstructural parameters, with the exception of the fractal dimension by the PCM. Empirical models adequately correlated rheological properties with SFC and microstructure density. Compression modulus increased by a factor of about ten as SFC increased from 0.28 to 0.51. However, for systems with the same SFC, compression modulus was dependent on microstructure. At low SFC compression modulus increased by about a factor of seven over the range of microstructures formed, whereas at higher SFC compression modulus only increased by a factor of about two.     

Three-dimensional numerical study of heat and mass transfer in fluidized beds with spray nozzle

The numerical computations of temperature and concentration distributions inside a fluidized bed with spray injection in three-dimensions are presented. A continuum model, based on rigorous mass and energy balance equations developed from Nagaiah et al., is used for the three-dimensional simulations. The three-dimensional model equation for nozzle spray is reformulated in comparison to Heinrich. For solving the non-linear partial differential equations with boundary conditions a finite element method is used for space discretization and an implicit Euler method is used for time discretization.The time-dependent behavior of the air humidity, air temperature, degree of wetting, liquid film temperature and particle temperature is presented using two different sets of experimental data. The presented numerical results are validated with the experimental results. Finally, the parallel numerical results are presented using the domain decomposition methods.     

Numerical modeling of effect of slot on bubble motion in aluminum electrolytic process

A transient three-dimensional (3D) model was established to understand the bubble motion in an industrial electrolytic process. An anode with a new design was tested. It incorporates two slots that allow an efficient removal of gas bubbles. The electromagnetic fields were described by solving Maxwell's equations. The bubble movement was studied with two-way coupling Euler–Lagrange approach. The interplay of current density and bubble nucleation rate was included. The collision and coalescence of bubbles were considered. Random walk module was invoked for involving the chaotic effect of the turbulence. The numerical results were validated by experimental measurements. The results indicate that the current distribution and the bubble nucleation periodically change. Due to the slot, the bubble elimination heavily increases. The contribution of the slot to the bubble removal exceeds 50% in the case of three currents, and the promotion of the slot decays with increasing the current.     

软黏土不排水循环应力应变关系的数值模拟

对程星磊等提出的总应力形式增量弹塑性本构模型进行二次开发,以模拟复杂应力状态下软黏土的响应。通过Newton-Raphson算法,对材料非线性问题进行迭代求解;针对本构模型中应力反向等一系列关键性问题,应用欧拉切线算法编写了有限元程序,并结合子增量方法提高了计算精度。预测了软黏土在轴对称应力状态下的响应,得到了应力应变关系曲线,将其与单元预测结果进行比较,二者趋于一致,从而验证了有限元程序编写的合理性。利用该程序模拟三轴不固结不排水试验,模拟结果与试验吻合良好,表明该本构模型有限元程序可以反映轴对称应力状态下软黏土的不排水应力应变特性,可应用于更加复杂边值问题的模拟计算。     

利用欧拉算法反演磁性界面

磁性地质界面的反演是地理物理勘探的重要课题之一。对提高磁测资料的地质解释效果具有重要意义,本文介绍了反演磁性界面的欧拉算法及其实际应用。     

基于SPH-ALE方法的波浪水槽数值模拟

为了精确模拟波浪传播,基于光滑粒子流体动力学及任意拉格朗日欧拉(SPH-ALE)方法建立二维数值波浪水槽,在原SPH方法中引入近似黎曼求解器替代人工黏性项,采用排斥力边界条件防止流体粒子穿透固边界,海绵层内采用指数型衰减函数来消除水槽末端的波浪反射,并对规则波的传播进行数值模拟。结果表明:与采用人工黏性项的原SPH方法相比,SPH-ALE方法能够无衰减地模拟波浪传播,并可有效减小固边界附近的粒子压力振荡。     

Time stepping in discontinuous Galerkin method

The time discretization in the Discontinuous Galerkin (DG) scheme has been traditionally based on the Total Variation Diminishing (TVD) second-order Runge-Kutta (RK2) scheme. Computational efficiency and accuracy with the Euler Forward (EF) and the TVD second-order RK2 time stepping schemes in the DG method are investigated in this work. Numerical tests are conducted with the scalar Burgers equation, 1-D and 2-D shallow water flow equations. The maximum Courant number or time step size required for stability for the EF scheme and RK2 scheme with different slope limiters are compared. Numerical results show that the slope limiters affect the stability requirement in the DG method. The RK2 scheme is generally more diffusive than the EF scheme, and the RK2 scheme allows larger time step sizes. The EF scheme is found to be more efficient and accurate than the RK2 scheme in the DG method in computation.