大型多支承变刚度回转窑支承载荷分配问题

回转窑是冶金、水泥、耐火材料生产中的核心设备，是一种重载、大扭矩、多支点、静不定运行系统，由于其载荷和刚度分布复杂、各支承存在偏移，作用在它托轮上的支承载荷分配严重不均。本文针对回转窑载荷和刚度分布的特点，建立支承载荷求解的力学模型和线性方程组，导出支承载荷分配与支承偏差的关系式；用该方法对现场回转窑进行计算，得出该窑支承载荷分配的线性公式和一些分析结论，为生产中回转窑的状态分析、优化调控提供依据。     

论瞬时轴线垂直度、平均回转轴线垂直度与Wobble的关系

用姿态变换的方法推导了平均轴线垂直度、瞬时轴线垂直度和倾角回转误差（Wobble)三之间的关系，从而得出了瞬时轴线垂直度和平均回转轴线垂直度的数据处理方法。     

Cargo Pendulation Reduction of Ship-Mounted Cranes

Ship-mounted cranes are used to transfer cargo from large container ships to smaller lighters when deep-water ports are not available. The wave-induced motion of the crane ship can produce large pendulations of the cargo being hoisted and cause operations to be suspended. In this work, we show that it is possible to reduce these pendulations significantly by controlling the slew and luff angles of the boom. Such a control can be achieved with the heavy equipment that is already part of the crane so that retrofitting existing cranes would require a small effort. Moreover, the control is superimposed on the commands of the operator transparently. The successful control strategy is based on delayed feedback of the angles of the cargo-hoisting cable in and out of the plane of the boom and crane tower. Its effectiveness is demonstrated in a fully nonlinear three-dimensional computer simulation and in an experiment with a 1/24th-scale model of a T-ACS (The Auxiliary Crane Ship) crane mounted on a platform moving with three degrees of freedom. The results demonstrate that the pendulations can be significantly reduced, and therefore the range of sea conditions in which cargo-transfer operations can take place can be greatly expanded.     

双层旋转壳流固耦合振动有限元分析

本文采用旋转壳体元和流体元分析了双层旋转壳体流固耦合振动特性,基于Novozhilov壳体理论、水弹性理论以及Hamilton变分原理推导出耦合系统运动方程,计算结果与实测值比较表明本分析方法有较好的精度。     

Dynamic analysis of geometrically nonlinear robot manipulators

In this paper, a method for the dynamic analysis of geometrically nonlinear elastic robot manipulators is presented. Robot arm elasticity is introduced using a finite element method which allows for the gross arm rotations. A shape function which accounts for the combined effects of rotary inertia and shear deformation is employed to describe the arm deformation relative to a selected component reference. Geometric elastic nonlinearities are introduced into the formulation by retaining the quadratic terms in the strain-displacement relationships. This has lead to a new stiffness matrix that depends on the rotary inertia and shear deformation and which has to be iteratively updated during the dynamic simulation. Mechanical joints are introduced into the formulation using a set of nonlinear algebraic constraint equations. A set of independent coordinates is identified over each subinterval and is employed to define the system state equations. In order to exemplify the analysis, a two-armed robot manipulator is solved. In this example, the effect of introducing geometric elastic nonlinearities and inertia nonlinearities on the robot arm kinematics, deformations, joint reaction forces and end-effector trajectory are investigated.     

无约束修正Timoshenko梁的冲击问题

介绍了修正后的Timoshenko梁运动方程，并比较了修正Timoshenko梁与经 典Timoshenko梁的运动方程. 推导了考虑剪切变形引起的转动惯量的修正Timoshenko 梁的正交条件，推导了集中质量对无约束修正Timoshenko梁的正碰撞对梁所引起的瞬态冲 击响应公式，并用算例进行了分析，且与集中质量对经典的无约束Timoshenko梁的正碰撞 对梁所引起的冲击响应进行了比较，另外还用算例分析了梁的刚度的变化和冲击质量比对其 冲击响应产生的影响.     

基于工作电流分析的回转副摩擦状态识别实验研究

回转副摩擦状态的变化对机械设备的运行有着重要影响. 针对回转副摩擦状态的识别问题, 设计了以回转副工作电流为摩擦特征来源的实验方案. 通过采集摩擦过程的回转副驱动电机工作电流信号, 分析实验信号的频域和时频域特征, 建立工作电流的摩擦特征库, 用于训练多分类支持向量机分类器, 并在分类器上完成摩擦状态的识别. 实验结果表明, 经特征提取与降维处理后建立的多分类支持向量机分类器具有近90%的识别正确率, 所提出的实验方案有利于实现远距离信号的采集, 适用实际生产加工.     

双轴转台的八位置调平及失准角估算

重力梯度旋转平台调制实验时要求旋转平台台面的水平失准角在一定范围之内。使用两位置正交方法对双轴转台进行调平时,能保证正交两个方向上水平精度,但无法保证在多个方向上的水平精度。对此,提出了一种八位置调平方法,即将整周360°分为八个位置,两个相邻位置的夹角为45°,依次测量八个位置的水平失准角,取最大值和最小值之和的二分之一作为中值,每个位置失准角与中值求差,通过差值的符号并结合八位置图确定调高或调低相应的地脚。同时,给出了一种通过匀速旋转调制来估算台面最大水平失准角的方法。实验表明:在目前实验条件下,八位置调平方法能将转台台面最大失准角控制在3″以内,旋转调制估算的水平失准角为2.9″。     

A high‐precision instrument for mapping of rotational errors in rotary stages

A rotational stage is a key component of every X‐ray instrument capable of providing tomographic or diffraction measurements. To perform accurate three‐dimensional reconstructions, runout errors due to imperfect rotation (e.g. circle of confusion) must be quantified and corrected. A dedicated instrument capable of full characterization and circle of confusion mapping in rotary stages down to the sub‐10 nm level has been developed. A high‐stability design, with an array of five capacitive sensors, allows simultaneous measurements of wobble, radial and axial displacements. The developed instrument has been used for characterization of two mechanical stages which are part of an X‐ray microscope.     

Direct on-strip analysis of size- and time-resolved aerosol impactor samples using laser induced fluorescence spectra excited at 263 and 351 nm

We report a novel atmospheric aerosol characterization technique, in which dual wavelength UV laser induced fluorescence (LIF) spectrometry marries an eight-stage rotating drum impactor (RDI), namely UV-LIF-RDI, to achieve size- and time-resolved analysis of aerosol particles on-strip. The UV-LIF-RDI technique measured LIF spectra via direct laser beam illumination onto the particles that were impacted on a RDI strip with a spatial resolution of 1.2 mm, equivalent to an averaged time resolution in the aerosol sampling of 3.6 h. Excited by a 263 nm or 351 nm laser, more than 2000 LIF spectra within a 3-week aerosol collection time period were obtained from the eight individual RDI strips that collected particles in eight different sizes ranging from 0.09 to 10 μm in Djibouti. Based on the known fluorescence database from atmospheric aerosols in the US, the LIF spectra obtained from the Djibouti aerosol samples were found to be dominated by fluorescence clusters 2, 5, and 8 (peaked at 330, 370, and 475 nm) when excited at 263 nm and by fluorescence clusters 1, 2, 5, and 6 (peaked at 390 and 460 nm) when excited at 351 nm. Size- and time-dependent variations of the fluorescence spectra revealed some size and time evolution behavior of organic and biological aerosols from the atmosphere in Djibouti. Moreover, this analytical technique could locate the possible sources and chemical compositions contributing to these fluorescence clusters. Advantages, limitations, and future developments of this new aerosol analysis technique are also discussed.