大挠度钻柱强度分析的平衡微分方程法

对小井眼、大曲率井中钻柱强度问题,以井轴为基准轴,在对井轴弯挠描述和钻柱微段三维受力变形分析的基础上,建立大位移钻柱平衡微分方程,采用Longe-Kutta法解之求内力,并依此求应力和建立强度条件.对H767侧钻水平井施工中钻柱应力计算分析,结果说明与有限元模型和弹性化软绳模型比较相吻合,该模型比有限元模型计算简捷方便;比弹性化软绳模型更完善可信;该井钻柱破坏事故愿因在于井眼曲率过大,兼有应力集中.     

On dynamics of elastic rod based on exact Cosserat model

The analysis of kinematics and dynamics of an elastic rod with circular cross section is studied on the basis of exact Cosserat model under consideration of the tension and shear deformation of the rod. The dynamical equations of a rod with arbitrary initial shape are established in general form. The dynamics of a straight rod under axial tension and torsion is discussed as an example. In discussion of static stability in the space domain the Greenhill criteria of stability and the Euler load are corrected by the influence of tension and shear strain. In analysis of dynamical stability in the time domain it is shown that the Lyapunov and Euler stability conditions of the rod in space domain are the necessary conditions of Lyapunov's stability in the time domain. The longitudinal, torsional and lateral vibrations of a straight rod based on exact model are discussed, and an exact formula of free frequency of lateral vibration is obtained. The free frequency formulas of various simplified models, such as the Rayleigh beam, the Kirchhoff rod, and the Timoshenko beam, can be seen as special cases of the exact formula under different conditions of simplification.     

具有初应力的1-3型压电复合材料的横向共振分析

1-3型压电复合材料在极化处理过程中会出现极化残余应力,基于线性压电理论,采用解析方法研究了极化残余应力对1-3型压电复合材料的横向共振模态的影响．首先建立含有初始应力的平面波波动方程,基于Bloch波函数理论构建了位移和电势函数,从而最终得到方程的解．数值结果表明初始残余应力的出现降低了复合材料的横向振动频率,而材料的压电性则使得横向振动频率提高．初始剪应力对对横向振动的频率影响较小,可以忽略．第一阶及第二阶振动频率将随着初始应力的大小呈线性变化．得出的结论对超声换能器的制作和研究将提供有意义的指导作用．     

梯形应力脉冲在弹性杆中的传播过程和几何弥散

在应力波传播过程中,几何弥散效应往往难以避免.对应力波在弹性杆中传播的几何弥散效应进行解析分析,对于基础波动问题研究以及材料动态力学行为表征等课题,显得至关重要.本文简单说明了弹性杆中考虑横向惯性修正的一维 Rayleigh-Love应力波理论,概述了其波动控制方程的变分法推导过程;针对 Hopkinson杆实验中常用的梯形应力加载脉冲,建立了相应的偏微分方程初边值问题的求解模型,并运用 Laplace变换方法研究了脉冲在杆中传播的几何弥散现象;根据留数定理进行 Laplace反变换,给出了杆中不同位置和时刻的应力波的级数形式解析解,分析了计算项数对结果收敛性的影响;将解析计算结果与采用三维有限元数值模拟的计算结果进行对比,两者吻合程度良好,从而证明 Rayleigh-Love横向惯性修正理论可以有效地表征典型 Hopkinson杆实验中的几何弥散效应.在此基础上围绕梯形加载脉冲的弥散效应进行参数研究,定量描述了传播距离、泊松比、脉冲斜率等参数的影响.本文给出的 Rayleigh-Love杆在梯形加载条件下的解析解,揭示了几何弥散效应的本质规律,可以用于实际实验的弥散修正过程.      

Summary of ISO/TC 201 International Standard ISO 18516:2019 Surface chemical analysis—Determination of lateral resolution and sharpness in beam-based methods with a range from nanometres to micrometres and its implementation for imaging laboratory X-ray photoelectron spectrometers (XPS)

ISO 18516:2019 Surface chemical analysis—Determination of lateral resolution and sharpness in beam-based methods with a range from nanometres to micrometres revises ISO 18516:2006 Surface chemical analysis—Auger electron spectroscopy and X-ray photoelectron spectroscopy—Determination of lateral resolution. It implements three different methods delivering parameters useful to express the lateral resolution: (1) the straight edge method, (2) the narrow line method and (3) the grating method. The theoretical background of these methods is introduced in ISO/TR 19319:2013 Surface chemical analysis—Fundamental approaches to determination of lateral resolution and sharpness in beam-based methods. The revised International Standard ISO 18516 delivers standardized procedures for the determination of the (1) effective lateral resolution by imaging of square-wave gratings, the (2) lateral resolution expressed as the parameter D_12–88 characterizing the steepness of the sigmoidal edge spread function (ESF) determined by imaging a straight edge and (3) the lateral resolution expressed as the full width of half maximum of the line spread function (LSF), w_LSF, determined by imaging a narrow line. The last method also delivers information on the shape of the LSF, which characterizes an individual imaging instrument. Finally, the implementation of all three standardized methods in the field of imaging laboratory X-ray photoelectron spectroscopy (XPS) is shortly presented. This part of the letter is based on the use of a new test sample developed at ETH Zurich, Switzerland. This test sample displays a micrometre scaled pattern motivated by the resolving power of recent imaging XPS instruments.     

高温超导磁悬浮系统中横向运动对悬浮力和导向力影响的研究

高温超导磁悬浮列车在运行过程中，导轨磁场的不连续或者机电耦合会引起车身的横向偏移．针对这一实际问题，本文研究了横向运动对竖直悬浮力和水平导向力的影响．实验中系统同时测试横向运动过程中不断变化悬浮力和导向力．研究发现运动过程中的悬浮力衰减与最大横向偏移量和往返运动次数有关；但导向力在第一次往返运动之后的往返运动中迟滞曲线基本不变．该工作可能为高温超导磁悬浮列车系统提供一定科学依据．     

Convergent-Divergent Nozzle under Highly Overexpanded Conditions

Quantitative results for the thrust and flow-rate performance of axisymmetric nozzles in highly overexpanded regimes are presented. Estimates for the lateral component of the reactive force and its range of possible existence are obtained for axisymmetric nozzles differing in the divergent region geometry. Empirical formulas for the gas flow rate in the subcritical outflow regime and the pressure range on which this regime can take place are proposed.     

相位测量轮廓术中三维坐标校准新方法

提出了一种新的用于相位测量轮廓术中的三维坐标校准方法。该方法用一个含有三个虚拟校准平面的标准块代替传统相位测量轮廓术校准方法中使用的标准平面，每个虚拟校准平面由多个高度相同但空间离散分布的子区域组成，相应的连续相位恢复是通过一个迭代过程实现的，同时各个子区域还被用于横向坐标的校准。由于各个虚拟校准平面间高度是垂直变化的，传统的相位展开不能得到正确的相对位置关系，基于等效波长概念，提出了一种准确的虚拟校准平面连续相位间相对位置恢复的办法。此校准方法的特点是：在校准过程中不需要标准平面的多次精确平移；仅需要一次测量就可以完成高度和横向坐标的同时校准。文中给出的实验结果说明了该校准方法的有效性和可行性。     

Dynamic and thermodynamic consequences of adsorbate lateral interactions in surface reaction kinetics

The effects of lateral interactions on the two-dimensional distribution of adspecies on solid surfaces and their consequences for reaction kinetics are demonstrated for the bimolecular reactive systemA+BAB. The discussion concentrates on systems where one reactant,A, is stationary while the other,B, is freely diffusing and instantaneously relaxing. A modified Bethe-Peierls-type lattice gas approximation is formulated in order to account for the rapidly-equilibrating distribution ofB atoms. The approximation takes into account all nearest and next nearest neighbor interactions between the adspecies and the nonuniformity of the lattice available toB implied by the presence of immobileA's on the surface. This model is combined with a Monte Carlo simulation of the reactive events in order to calculate reaction rates, e.g., in temperature-programmed processes. The rates are compared with full Monte Carlo simulations (for all kinetic processes), showing good agreement between the two schemes, except at very high coverages, where very long range correlations in the system which are ignored in the lattice gas approximation must be taken into account.This paper is dedicated to Howard Reiss in celebration of his 66th birthday.     

侧胸皮瓣修复顽固性扁平疣一例

介绍了治疗顽固性扁平疣的有效方法。本例患者起病两年多来由右手中指背针尖大的一个部位，发展到三个部位，且右中指创面发展到整个指甲边缘。期间曾行冷冻治疗、电灼治疗多次，内服、外用及肌注药物多种，均未奏效。最终行病灶切除缝合及侧胸部带蒂皮瓣移植，术后半年复查病灶未复发。可见手术切除方法是根治顽固性扁平疣的有效方法，侧胸部皮瓣为手指创面修复较理想部位。