OPERATOR-SPLITTING METHOD FOR ANALYSIS OF CAVITATION IN LIQUID-LUBRICATED HERRINGBONE GROOVED JOURNAL BEARING

ＮＯＭＥＮＣＬＡＴＵＲＥｃ　ｒａｄｉａｌｃｌｅａｒａｎｃｅｈ　ｆｉｌｍｔｈｉｃｋｎｅｓｓ ｈ　ｄｉｍｅｎｓｉｏｎｌｅｓｓｆｉｌｍｔｈｉｃｋｎｅｓｓ (ｈ/ｃ)Ｌ/Ｄ　ｒａｔｉｏｏｆｌｅｎｇｔｈｔｏｄｉａｍｅｔｅｒｐ　ｆｉｌｍ ｐｒｅｓｓｕｒｅｅ　ｅｃｃｅｎｔｒｉ     

地震和测井联合反演储层波阻抗技术

通过地震和测井联合反演，可以获得高分辨率的井间地层波阻抗分布的信息。综合应用波动方程反演和神经网络分析来反演地层波阻抗参数，其过程分3步：第一步，应用先验地质知识，对地震数据和测井曲线进行地质解释，并对油井曲线进行对层和标定，然后求取相应的层速度的低频信息，旨在搞清井间地层结构状况，为线性反演提供地层产状的先验信息；第二步，应用非线性波动方程反演，在层速度界面及井中物性参数约束下，从地震数据中反演高分辨率的反射系数及波阻抗参数；第三步，应用CUSI神经网络分析方法，以高分辨率的反射系数及波阻抗等参数作为约束，以沿层求取的地震特征作为输入，以井中反演的波阻抗参数为期望输出，对非线性波动方程反演出的波阻抗参数进行非线性标定，得出井间的地层绝对波阻抗物性参数。     

GENERATION OF NONLINEAR INTERNAL WAVES ON CONTINENTAL SHELF

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｅｒｎａｌｔｉｄａｌｉｎｔｅｒａｃｔｉｏｎｗｉｔｈｂｏｔｔｏｍｆｅａｔｕｒｅｓａｐｐｅａｒｓｔｏｂｅｔｈｅｄｏｍｉｎａｎｔｍｅｃｈａｎｉｓｍｆｏｒｇｅｎｅｒａ ｔｉｏｎｏｆｔｈｅｃｏｈｅｒｅｎｔｏｃｅａｎｉｃｉｎｔｅｒｎａｌｗａｖｅｓｔｈａｔａｒｅｏｂｓｅｒｖａｂｌｅｗｉｔｈＳＡＲ ,ｃｌｏｓｅｒｔｏｓｈｏｒｅ ,ｒｉｖｅｒｉｎｅｏｒｇｌａｃｉａｌｉｎｔｒｕｓｉｏｎａｎｄｃｏｎｔｉｎｅｎｔａｌｂｒｅａｋｐｒｏｖｉｄｅｓｅｃ ｏｎｄａｒｙｇｅｎｅｒａｔｉｎｇｍｅｃｈａ…     

毫米波谐波振荡器的Volterra级数分析法

本文基于Ｖｏｌｔｅｒｒａ级数法和非线性转移函数理论，提出了一种分析毫米波谐波振荡器的新方法，给出了描述其非线性特性的决定方程，通过求解一组非线性代数方程，便可计算出谐波振荡器的振荡频率和幅度。文中给出了具体分析实例，并与谐波平衡法等进行了比较，结果表明：这种方法具有理论严密、准确性高、适用范围广等特点，特别是利用一次决定方程的结果作为其它非线性数值分析方法的初始估值，则可大大地节约计算时间，并容易     

群时延精确设计的全差分四阶Bessel滤波器

采用MOS管有源电阻,提出了一种全差分R-MOSFET-C四阶Bessel有源低通滤波器,.通过调节工作于亚阈值区的CMOS管的沟道导纳补偿电阻值的大小,能抵消集成电路制造工艺中电阻值的一致偏差,实现Bessel有源滤波器群时延的精确设计.根据无源滤波器的状态方程完成有源滤波器的综合,应用3.3V,0.5μm CMOS工艺完成了群时延大小为0.75μs的四阶Bessel低通滤波器的管极计算机仿真,仿真结果表明所提电路正确有效,适于全集成.     

Adhesive Contact of a Membrane with a Hemispherical Indenter: Theoretical Analysis and Model Liquid System

The axisymmetric Laplace equation is solved numerically to extract contact-angle data for a flat liquid/vapor interface contacting a submerged hemispherical solid. The liquid/vapor interface is treated as a membrane, with a membrane tension equal to the surface energy of the liquid. By measuring the vertical displacement of the membrane and the projected contact area the membrane makes with the hemisphere, the contact angle and correspondingly the driving force for motion of the contact line can be measured. We show that characteristic receding and advancing contact angles can be obtained by measuring the contact radii formed upon initial contact between the interface and hemisphere and final contact just prior to detachment of the interface, respectively. Use of the technique is illustrated with a model experiment involving the contact of an air/water interface with a poly(methyl methacrylate) surface.     

Mathematical analysis of viscometric (polymer) flow fields in capillaries: Taylor dispersion revisited

A general formulation for capillary flow of two miscible fluids – one a dilute plug of polymer fluid inserted into a fully developed Poiseuille flow of the other, a Newtonian stream – is examined for its long time behavior. Phenomenologically, the system evolves from an initial state, that of a plug within the boundaries of sharp, well defined fronts inside a Newtonian stream, to a more homogenized state in the very long time scale. This problem was addressed by G.I. Taylor but with regard to a system of two Newtonian fluids, leading to the well-known results commonly described as `Taylor axial dispersion'. In this paper, a general and systematic perturbation analysis is presented from which Taylor's result is recovered as a special case of a more general solution which applies to fluids incorporating elastic properties. In particular, the influence of viscoelasticity and (polymer) diffusivity on the observed pressure profile in the capillary conduit is examined. This effect is clearly separated out for small Peclet number flows using asymptotic and numerical analysis. The results identify the influence of fluid viscosity, elasticity, and diffusivity on the observed pressure profile and form the basis for the improved characterization of polymeric elasticity using capillaries – a finding that is of significant scientific and commercial interest. These results were obtained by the authors as a class of observations resulting from the perturbation analysis of forced-flow capillary devices in viscoelastic fluid property investigation.     

Non‐reflecting artificial boundaries for transient scalar wave propagation in a two‐dimensional infinite homogeneous layer

This paper presents an exact non‐reflecting boundary condition for dealing with transient scalar wave propagation problems in a two‐dimensional infinite homogeneous layer. In order to model the complicated geometry and material properties in the near field, two vertical artificial boundaries are considered in the infinite layer so as to truncate the infinite domain into a finite domain. This treatment requires the appropriate boundary conditions, which are often referred to as the artificial boundary conditions, to be applied on the truncated boundaries. Since the infinite extension direction is different for these two truncated vertical boundaries, namely one extends toward x →∞ and another extends toward x→‐ ∞, the non‐reflecting boundary condition needs to be derived on these two boundaries. Applying the variable separation method to the wave equation results in a reduction in spatial variables by one. The reduced wave equation, which is a time‐dependent partial differential equation with only one spatial variable, can be further changed into a linear first‐order ordinary differential equation by using both the operator splitting method and the modal radiation function concept simultaneously. As a result, the non‐reflecting artificial boundary condition can be obtained by solving the ordinary differential equation whose stability is ensured. Some numerical examples have demonstrated that the non‐reflecting boundary condition is of high accuracy in dealing with scalar wave propagation problems in infinite and semi‐infinite media. Copyright © 2003 John Wiley & Sons, Ltd.     

Analytical solution for the axisymmetric plane strain electroelastic dynamics of a special non-homogeneous piezoelectric hollow cylinder

By virtue of the introduction of a dependent variable and the separation of variables technique, the axisymmetric plane strain electroelastic dynamic problem of a special non-homogeneous piezoelectric hollow cylinder is transformed to a Volterra integral equation of the second kind about a function with respect to time, which can be solved successfully by means of the interpolation method. Then the solutions of displacements, stresses, electric displacements and electric potential are obtained. The present method is suitable for a piezoelectric hollow cylinder with an arbitrary thickness subjected to arbitrary mechanical and electrical loads. Numerical results are finally presented.     

水平井眼轨迹对气井出砂趋势及工作制度的影响

出砂是影响油气井正常生产的重要因素之一。借助FEPG有限元程序自动生成平台，建立了三维应力场弹塑性地层出砂模型，并运用有限元法计算分析了不同轨迹的裸眼井井壁周围的有效塑性应变分布规律及出砂趋势，研究了气藏压力衰竭对完井方式的影响。研究表明，水平井眼轨迹对出砂有重要的影响，同一地应力环境下向不同方位延伸的水平井在投产时应该采取不同的生产压差和不同的生产制度，水平井眼轨迹对出砂的影响程度随着3个地应力差异的增大而加剧。气藏压力衰竭对井壁的稳定性和出砂趋势都有重要影响。随着气藏压力的衰竭，井壁稳定性将变得越来越差，最终导致井筒出砂。因此，对气井完井不仅应该考虑到气藏开发初期地层的稳定性状况，而且还应该考虑到气藏压力衰竭后可能出现的井壁失稳问题。