实验室的质量监督(上)

质量监督是实验室保持人员能力,进行自我完善,日常渐进的重要手段,是持续改进的重要组成部分,也是实验室管理工作的难点,本文给出质量监督的目的、对象、方法、记录等.     

Cartesian grid methods using radial basis functions for solving Poisson, Helmholtz, and diffusion–convection equations

Four methods that solve the Poisson, Helmholtz, and diffusion–convection problems on Cartesian grid by collocation with radial basis functions are presented. Each problem is split into a problem with an inhomogeneous equation and homogeneous boundary conditions, and a problem with a homogeneous equation and inhomogeneous boundary conditions. The former problem is solved by collocation with multiquadrics, whereas the latter problem is solved by collocation with either multiquadrics or fundamental solutions. It is found that methods that make use of fundamental solutions for collocation yield more accurate solutions that are less sensitive to the shape parameter of multiquadrics and node arrangement. Additional collocation appears to improve the quality of solutions.     

低渗透率地层渗透率的确定方法

结合大庆油田外围低渗透率地层的地质特点,根椐渗流理论和岩心分析资料,分析了地层渗透率与孔隙度、组成地层的各种矿物含量以及泥质含量之间的关系,建立了不同矿物组合地层的渗透率计算方程。用本方法计算的和岩心分析的渗透率进行了对比,二者之间具有较好的一致性。     

射孔孔眼中散射超声脉冲波的FEM模拟

采用有限元素法 ,分别数值计算了平底孔道、台阶式孔道和尖劈状孔道等 3种孔眼模型中不同中心频率 (10 0 k Hz、5 0 0 k Hz、1MHz)的散射超声脉冲波。计算结果表明 ,无论选用哪一种孔底模型 ,均可以得到较为明显的对应于孔底的声波信号。但是 ,孔道越不规则 ,使用的超声信号的主频越高 ,则孔底信号越差。为了兼顾孔底信号质量和信号采集、传输的代价 ,在未来的检测仪器中应采用尽可能低的测量频率 (低于 5 0 0 k Hz)     

复合乳化沥青的粘附性试验方法研究

鉴于目前使用的阳离子乳化沥青粘附性试验方法难以有效评价复合乳化沥青粘附性，通过试验研究并综合考虑乳化沥青施工和路用实际情况，提出了乳化沥青水煮法试验方法和采用该方法检验复合乳化沥青粘附性时的评定标准。     

Free vibration of partially supported piles with the effects of bending moment, axial and shear force

The pile parts above the soil and embedded in the soil are called the first region and the second region, respectively. The fourth order partial differential equations of both regions for free vibration of partially supported pile subjected to bending moment, axial force and shear force are obtained using the small-displacement theory and the Winkler model. It is assumed that the behavior of the material is linear-elastic, and that axial force along the pile length and modulus of subgrade reaction for the second region to be constant. Shear effect is included in the partial differential equations by the second derivative of the elastic curve function with respect to shear deformation. Natural circular frequencies and relative stiffness of the pile are calculated for non-trivial solution of linear homogeneous system of equations obtained due to the values of axial forces acting on the pile, the shape factors, and the boundary conditions of the pile with both ends free and both ends simply supported; the results are presented in graphs.     

Numerical simulation of typical contact situations of brake friction materials

In the paper, a model typical for contact situations of automotive brakes is established based on the method of movable cellular automata. The processes taking place at local contacts in an automotive brake system are analysed. Based on microscopic and micro-analytical observations, the following contact situations were simulated: (i) a couple of ferritic steel against pearlitic steel, both covered by an oxide layer mixed with graphite nanoparticles and (ii) the same situation but without oxide layers. The results of calculated mean coefficients of friction of the oxide-on-oxide contact correspond well to expected values for a real braking system, whereas steel-on-steel contact are twice as high. This allows one to make some conclusions; for example, oxide formation will take place more quickly than friction layer elimination, and finally this is responsible for the stabilisation of the coefficient of friction.     

Preparation of CeO2-ZrO2 mixed oxide with high surface area and high thermal stability

Ceria-zirconia solid particles have been recognized as a key material of the automotive exhaust catalysts since they can release and uptake oxygen owing to the rapid reversible oxidation states of cerium between Ce³⁺ and Ce⁴⁺. Several methods have recently been described to prepare the CeO₂-ZrO₂ solid particles used in the catalysts. In this paper, a new coprecipitation method is used to prepare the CeO₂-ZrO₂ solid particles. The Ce-Zr alcogel is dried and calcined in flowing N₂ not in flowing air under atmospheric pressure. The results show that the ceria-zirconia sample calcined at 650 °C has high surface area over 90 m²g⁻¹, which drops to 40 m²g⁻¹ following treatment at 900°C.     

Numerical simulation of flying phenomena of the running tape on rotating drum

This paper analyzes the running mechanism of flexible and thin tape above rotating protrusion through a numerical simulation. The scope of analysis is confined to the phenomena of elastohydrodynamic lubrication between the rotating drum with a protrusion and the running tape. This model is based on the modified Reynolds equation and the equation of plate considering the effect of geometric nonlinearity and geometry of protrusion. Finite element method of Bubnov-Galerkin type is adopted as a numerical simulation technique to solve the above two coupled nonlinear equations. In numerical simulation, the influences of tape tension and protrusion velocity are evaluated in simple model. In complex models, the reciprocal action of two protrusions is simulated.     

钻速模式动态辨识方法研究

目的：钻进过程是一个复杂的工艺过程，影响钻速的因素错综复杂。为钻井参数优化和实时控制，提出钻速动态模型。方法：对影响钻速的因素进行分析，用系统辨识方法建立钻速模式。结果：利用该方法建立了华北油田岔河集地区的钻速模型，取得满意结果。结论：此动态钻速模式能更准确、科学地描述钻进过程，并在钻井参数最优化、钻井过程的闭环控制等方面具有广阔的应用前景。