隔水管弯曲对钻柱振动影响的计算与分析

海洋油气资源钻探中隔水管的弯曲对钻柱振动以及钻进特性有特别的影响。为得到隔水管弯曲对钻柱振动的影响规律,对南海已钻深水井使用非线性有限元软件建立全井钻井数值计算模型,研究获得了不同垂深时隔水管弯曲对钻柱振动特性的影响规律。研究表明:隔水管弯曲会加剧钻柱的振动,钻柱振动加剧会导致钻井能耗上升、钻头切削能力下降并且会加快钻柱疲劳;当隔水管的弯曲达到某临界值,钻柱与隔水管间的接触力会陡增;井口的钩载越大,隔水管弯曲带来的井口钩载波动量越大;井越深,隔水管弯曲对全井钻柱最大弯矩和钻头切削能力的影响越小。     

进气道入口形状对冲压发动机性能影响数值研究

进气道是冲压发动机设计中非常重要的环节,其入口设计会直接影响冲压发动机的总压恢复系数σ和流量系数φ等重要性能。本文采用二阶迎风隐式TVD格式,内外流分区耦合求解可压缩N-S方程,数值模拟了掺混段出口压力与来流压力比为P/P∞=4.2超临界状态下,二元方形截面“X”型布局进气道、弹体和掺混段一体化通气模型复杂流场。计算比较了两种不同二元进气道入口形状流场和冲压发动机总压恢复系数σ、流量系数φ的结果,对其产生的原因进行了分析。     

On the existence of the derivative of the volume average

A general theorem on the derivative of the volume average is formulated and proved. Conditions for the existence of the derivative are presented and discussed. This is done in order to give a better base to the theory of spatial averaging.Latin Letters E ₃ three-dimensional vector space over the field of real numbers - K, K(x) averaging domain - G, G _w, G_s open sets in E ₃; components of the two-phase system - C ¹(G) the set of functions 1-times continuously differentiable in G - W1/2(G) Sobolev space - V volume of the domain K - f function defined in G, G _w - K _infi ^sup* (x), K _infi ^sup– (x) special parts of K(x) Greek Letters boundary of G, G _w, G_s; w-s interface - _ij Kronecker delta - v unit outward normal of G, G _w - _j j-dimensional Lebesgue measure Other M closure of a set M in the metric space E ₃ - f phase average of f for the w-phase - (u, v) scalar product of u, v in E ₃ - one-sided derivatives     

表面织构对刀具切削性能及前刀面摩擦特性的影响

为了研究刀具表面织构对切削性能的影响,通过控制前刀面上微凹坑的直径、深度和面积占有率等参数制备了两组表面高度算术平均值Sa相同的织构刀具.使用Talysurf CCI Lite非接触式三维光学轮廓仪对织构表面进行测量,采用ISO25178参数对测量表面进行表征;通过SL200KS接触角测量仪测量织构刀具前刀面湿润性的变化;随后在CA6140车床上进行45钢切削试验,研究不同织构对切削力、前刀面摩擦特性、工件表面粗糙度和切屑形变的影响.结果表明:合理的表面织构能够改善刀具的切削性能;切削液在前刀面铺展较快的织构刀具获得了较好的切削性能;凹坑直径、深度和面积占有率的协同作用对改善刀具切削性能至关重要,为了协调这三个织构参数,进一步研究三维表征参数Sku、Ssk、Sv、Vvv、Vvc、Sdv、Sda、Spd与刀具切削性能的关联性,为刀具表面设计提供了基础.     

On the derivation for the gradients of the principal invariants

In this notes, it is shown that the method carried out by Truesdell and Noll [1] for the gradients of the principal invariants is available to be used for arbitrary second-order A. Finally, some trace identities for the derivatives of invariants are given.     

On the criterion for the absolute stability of the control system

In this paper, firstly we give the criterion for the absolute stability of the second canonical form for the control system, including the equation of the longitudinal motions of a plane as a particular example. The corresponding result in [8], [9] is a particular example given in this paper. Secondly, we give the criteria for the absolute stability of the first canonical form in the usual case and in the critical case. Finally, we give some criteria for the absolute stability of the general form for the direct control system.All the results in this paper merely depend upon the relations between the parameters of the system itself to give an explicit algebraic discriminant.     

On the study of the initiation of the micro crack on the smooth surface of polycrystalline

Crystallographic plasticity was applied to study the initiation of micro cracks on the smooth surface of polycrystalline under uniform applied stress. Even under the uniform external stress, due to the different crystallographic orientations of the grains in the polycrystalline, there is un-uniform stress distribution and the deformation is also not uniform. Under the fatigue loading, the roughness increases with the number of fatigue, and deformation will localize in some places, where micro cracks form.     

地球与月球关系的研究

基于鹦鹉螺外壳生长线条数的变化是月亮绕地球运动周期随年代变化反映的假设, 采用外推 法得出两个结论: (1) 月球最初被地球俘获绕地球运动时距地球的距离为目前月地距离的0.2 倍左右; (2) 月球最初被地球俘获绕地球运动时的时间距今为7亿年左右. 这 为进一步研究地球与月球的关系提供了有益的启示.     

捷联式惯性导航系统惯性元件的设置与可靠性

本文对惯性元件的最佳冗余设置及其在飞行器上的布局与可靠性之间的关系进行了研究，建立了相应的可靠性数学模型，探讨了３／６（Ｇ）冗余惯性元件出现第三个故障时故障的检测与识别的方法。所得结果可供惯性导航系统可靠性分析及工程上应用。     

Singularities of the boundary layer equations and the structure of the flow in the vicinity of the convergence plane on conical bodies

The singularities of the boundary layer equations and the laminar viscous gas flow structure in the vicinity of the convergence plane on sharp conical bodies at incidence are analyzed. In the outer part of the boundary layer the singularities are obtained in explicit form. It is shown that in the vicinity of a singularity a boundary domain, in which the flow is governed by the shortened Navier-Stokes equations, is formed; their regular solutions are obtained. The viscous-inviscid interaction effect predominates in a region whose extent is of the order of the square root of the boundary layer thickness, in which the flow is described by a two-layer model, namely, the Euler equations in the slender-body approximation for the outer region and the three-dimensional boundary layer equations; the pressure is determined from the interaction conditions. On the basis of an analysis of the solutions for the outer part of the boundary layer it is shown that interaction leads to attenuation of the singularities and the dependence of the nature of the flow on the longitudinal coordinate, but does not make it possible to eliminate the singularities completely.     

光测力学技术：连接虚拟空间和现实世界的纽带

在轿车的整个开发过程中，零部件、总成和整车产品都必须根据试验结果验证和优化，在轿车开发的过程中测试技术是连接设计师思维空间和现实空间的纽带，现代光学测试技术以数字图象数据处理技术为基础，融汇贯通高速宽带数字采样、数据库和数据自动分析以及计算机智能工程及专家系统等最新技术，巧妙应用于轿车开发过程，在满足计算机虚拟开发工程对测试技术新要求的同时，还可以优化轿车开发程序，提高开发质量，本文以作者多年来在德国轿车开发部门主持的现代测试技术项目的实例介绍采用光测技术解决开发程序中的问题的构想，方法和手段。     

On the Global Geometric Structure of the Dynamics of the Elastic Pendulum

We approach the planar elastic pendulum as a singular perturbation of the pendulum to show that its dynamics are governed by global two-dimensional invariant manifolds of motion. One of the manifolds is nonlinear and carries purely slow periodic oscillations. The other one, on the other hand, is linear and carries purely fast radial oscillations. For sufficiently small coupling between the angular and radial degrees of freedom, both manifolds are global and orbitally stable up to energy levels exceeding that of the unstable equilibrium of the system. For fixed value of coupling, the fast invariant manifold bifurcates transversely to create unstable radial oscillations exhibiting energy transfer. Poincaré sections of iso-energetic manifolds reveal that only motions on and near a separatrix emanating from the unstable region of the fast invariant manifold exhibit energy transfer.     

On the equivalence of the Wilson element and the generalized hybrid element

In this paper the equivalence of the generalized hybrid element and the modified Wilson element, which is derived by the generalized hybrid method, is proved. The project is supported by the National Natural Science Foundation of China     

On the nonlinear dynamics of the traveling-wave solutions of the Serre system

We numerically study nonlinear phenomena related to the dynamics of traveling wave solutions of the Serre equations including the stability, the persistence, the interactions and the breaking of solitary waves. The numerical method utilizes a high-order finite-element method with smooth, periodic splines in space and explicit Runge–Kutta methods in time. Other forms of solutions such as cnoidal waves and dispersive shock waves are also considered. The differences between solutions of the Serre equations and the Euler equations are also studied.     

试论静力学在流体力学课程中的地位

从材料的本构方程和基本运动方程出发, 比较了静力学在弹性力学和流体力学中的 地位. 与弹性静力学在弹性力学中占有重要地位不同, 流体静力学在流体力学中仅处 于次要地位, 它不是流体动力学的基础, 而只是一个特例. 确立这种观点有助于提高对流体 力学学科特点的认识, 提高流体力学教学质量.     

Embracing the Random in the Self-Organizing Psyche

The history of the idea of randomness in the Nineteenth Century is presented as a backdrop to Freud's understanding of randomness in the psyche. Next, the role of the random event in nonlinear dynamical systems theory is discussed. Then, a revision of the traditional psychoanalytic view of the synthetic function of the ego is proposed based on the process of self-organization in which random elements are utilized in the emergence of new systemic structures. A theory of dreaming is elaborated which transcends the traditional dichotomy of dreams as either random events or meaningful psychological contents. Finally, remarks about psychoanalytic treatment as a process of self-organizing incorporation of the random are offered.     

On the sensitive dynamical system and the transition from the apparently deterministic process to the completely random process

The detailed analysis of the dynamical process of coin tossing is made. Through calculations, it is illustrated how and why the result is extremely sensitive to the initial conditions. It is also shown that, as the initial height of the mass center of the coin increases, the final configuration, i.e. head or tail, becomes more and more sensitive to the initial parameters (the initial velocity angular velocity, and the initial orientation), the coefficient of the air drag, and the energy absorption factor of the surface on which the coin bounces. If we keep the head upward initially but allow a small range for the change of some other initial parameters, the frequency that the final configuration is head, would be 1 if the initial height h of the mass center is sufficiently small, and would be clo to 1/2 if h is sufficiently large. An interesting question is how this frequency changes continuously from 1 to 1/2 as h increases. Detailed calculations show that such a transition is very similar to the transition from laminar to turbulent flows. A basic difference between the transition stage and the completely random stage is indicated: In the completely random stage, the deterministic process of the individual case is extremely sensitive to the initial conditions and the dynamical parameters, out the statistical properties of the ensemble are insensitive to the small changes of the initial conditions and the dynamical parameters. On the contrary, in the transition stage, both the deterministic process of the individual case and the statistical properties of the ensemble are sensitive to the initial conditions and the dynamical parameters. The mechanism for this feature of the transition stage is the existence of the long-train structure in the parameter space. The illuminations of this analysis on some other random phenomena are discussed.