具有新概念的运动误差及形状误差的分离法——虚位数据法

提出了一种基于信号重建的虚位数据法，用此方法，可以按需要任意选择只分离形状误差或只分离运动误差，或者任意安排分离这两类误差的先后顺序，而不必变更传统的形状误差检测－分离系统，方式灵活。     

形状误差统一算法的研究

本文运用线性极差和优化理论,将形状误差的评定归为线性规划的求解,研究出简单、精确、有效的统一算法,克服了置换、组合中多次循环的弊端,为基层厂矿提供了有效的实施方法。     

非球面表面形状的线测量技术

描述了一种在超精密磨削机床上基于误差分离法的非球面表面形状精密测量系统.首先,论述了一般用于平面形状测量的两点法不能直接用于非球面形状测量的原因在于测头的设置误差会引起很大的形状测量误差.提出了先通过两点法测量平面形状得出机床的运动误差,然后对测量非球面形状的另外一个测头的输出进行补偿以得出正确的非球面形状.用此系统测量了一个直径为30 mm的非球面镜头的表面形状.     

形状误差minimax问题的机器求解

本文研究最小条件意义下评定各项形状误差的统一计算法。在线性极差极小化理论的基础上,本文提出了“最佳作用点集合”的概念,将关于评定基准向量的连续最优化问题转化为关于作用点集合的组合最优化问题。进而,本文采用测量点的概率删点技术和评定基准向量的线性保号变换,使问题可采用成熟的Dantzig算法求解。从而,实现了形状误差评定中minimax问题的机器求解。     

出租车的计程误差线之形状

出租车,其计程误差线的形状,笔者试画出,并分析。     

一种精密测量径向回转运动误差的方法

利用三点法圆度误差分离原理,分离出被测截面圆度误差和截面最小二乘圆心的运动误差,在此基础上揭示了回转轴纯回转运动误差与工件最小二乘圆心初始位置之间的关系.利用这种关系及三角函数的正交性,推导出了分离纯回转运动误差的数学表达式.试验结果表明,本文所述方法可以实现回转轴径向回转运动误差的精密测量.     

用三点连环干涉法测量环形平面的形状误差

在生产中常遇到高精度圆环形平面的平面度误差测量问题。对于径向宽度远小于周向长度的较大环形平面,在缺乏相应的大平晶情况下,本文提出采用三点连环干涉法,沿圆环周向测量其环形端面的类直线度误差,以近似代替平面度误差的测量。     

机床直行部件运动误差测量的精度分析与对策

分析了经典频域三点法测量直行部件运动误差时所存在的谐波抑制，直线度误差的非周期性、非封闭性以及端点不连续而引起的高阶谐波分量失真等方法误差。为了减少上述方法误差，提出了一种新的时域两点法误差分离技术。首先对传感器拾取的数据做对称延拓，这样可以减小由于所采信号的非封闭性所引起的高阶谐波失真。利用频域三点法得到时域两点法所需要的叠代初值。采用现代控制理论研究了谐波抑制的产生机理。通过合理地配置传感器的安装位置可以优化测量系统的传递特性，减少谐波抑制的发生。该方法既可以得到机床直行部件的运动误差，又可以得到在该机床上加工零件的直线度形状误差，这些测量信息都有助于诊断机床的误差源。通过试验验证了该方法的有效性和精确性。     

用三坐标测量机测量抛物线曲面工件形状误差的方法

本文探讨了用三坐标机测量抛物面工件的方法，以及对测量数据的分析和处理。     

形状误差评定的拟合操作研究

本文探讨了基于产品几何技术规范(GPS)实现形状误差评定的规范过程,重点分析了操作算子应用技术中的拟合操作,包括拟合建模技术及拟合规划模型求解方法,并给出拟合策略的合理选用原则。进一步阐明了拟合操作在形状误差评定过程中的关键性作用。     

多重序列突变网络系统分析与应用

为分析多重生物序列的突变结构,首先是要作它们的多重比对,在多重比对基础上可作出各序列的系统树与最小距离树,在最小距离树中如果把它们的弧用突变模结构来表示,那么我们称由此所产生的数学模型为多重序列突变网络系统(以下简称突变网络),突变网络分析的主要问题是如何确定各种不同类型突变的相互关系问题,一种最简单关系是二个突变的突变区域互不重叠,我们称之为正交化。因此突变网络分析的一个重要目的是对突变网络作正交化的简化,本文给出了突变网络正交化的基本定理,并以SARS病毒基因组为例,说明它们的突变网络系统模型与正交化运算,并由此得到SARS病毒从早期传播到爆发的基因突变过程的确定。     

WS2含量对超音速等离子喷涂KF301／WS2润滑耐磨涂层摩擦学行为的影响

常规固体润滑涂层高温下不具备稳定的摩擦系数和较低的磨损率。为此,采用超音速等离子喷涂技术制备了KF301／WS2复合润滑耐磨涂层,探讨了复合润滑涂层中WS2润滑膜所呈现的自润滑效果及其作用机理。结果表明：涂层的磨损率随着WS2含量的变化而呈现较大的波动,WS2含量为30％时达到最小值,为1．22×10^-4mg／h;涂...     

Strain Engineering of 2D Materials: Issues and Opportunities at the Interface

Triggered by the growing needs of developing semiconductor devices at ever‐decreasing scales, strain engineering of 2D materials has recently seen a surge of interest. The goal of this principle is to exploit mechanical strain to tune the electronic and photonic performance of 2D materials and to ultimately achieve high‐performance 2D‐material‐based devices. Although strain engineering has been well studied for traditional semiconductor materials and is now routinely used in their manufacturing, recent experiments on strain engineering of 2D materials have shown new opportunities for fundamental physics and exciting applications, along with new challenges, due to the atomic nature of 2D materials. Here, recent advances in the application of mechanical strain into 2D materials are reviewed. These developments are categorized by the deformation modes of the 2D material–substrate system: in‐plane mode and out‐of‐plane mode. Recent state‐of‐the‐art characterization of the interface mechanics for these 2D material–substrate systems is also summarized. These advances highlight how the strain or strain‐coupled applications of 2D materials rely on the interfacial properties, essentially shear and adhesion, and finally offer direct guidelines for deterministic design of mechanical strains into 2D materials for ultrathin semiconductor applications.     

An Analysis of the Factors Influencing the Data Derived from a Plug Type Three-Dimensional Strain Rosette under Compression and Torsion

Abstract:  The embedding of three-dimensional strain rosettes embedded into epoxy models provides an experimental technique for analysing complex structures; however, this technique has been known to produce data that were difficult to explain in terms of their physical significance. To gain a greater insight into the behaviour of a three-dimensional strain rosette used in this way, a three-dimensional strain rosette was embedded into each of two separate prismatic bars of square cross-section and subjected to fundamental tests of compression and torsion in standard commercial testing machines. In initial tests on a bar containing a three-dimensional strain rosette (Bar A) the data derived from the individual gauges sometimes departed from the theoretical values by more that 30  μ e. After critical evaluation of the procedures used for making and testing Bar A, further tests were carried out on Bar B, which led to a reduction in the difference between theoretical and experimental data to 14  μ e, acceptable for most practical purposes. The use of square plugs containing three-dimensional strain rosettes which are embedded into square cavities in the model, and the measurement of the actual direction cosines of the gauges on the square plug prior to embedment is a distinct advantage over the use of cylindrical plugs. In addition, the use of testing machines with a fixed base as opposed to a floating lower platen is recommended.     

电场、应力和电荷态对Ti2CO2电子性质调控的理论研究

MXene是一类具备丰富物理化学性质的新型二维过渡金属碳化物, 在储能、催化、复合材料、发光材料等领域都表现出潜在的应用前景。元素掺杂、结构缺陷、表面功能化、外加电场、外加应力等方法是调节二维材料性能的有效手段。作为厚度最小和最轻的含钛MXene材料, Ti₂CO₂具有间接半导体特性, 本工作研究外加电场、外加应力和电荷态等条件对Ti₂CO₂电学性能的调控。结果表明：无缺陷Ti₂CO₂原胞的带隙随着外加电场的增强而变小。在Ti₂CO₂体系中, 碳空位较易形成。研究发现拉伸应力可以改变含碳空位体系的导电能力, 费米能级附近的能带随着拉伸应力的增大而逐渐平滑。研究还发现电荷态会改变含碳空位2×2×1 Ti₂CO₂超胞的能带结构, 随着电荷态的增加, 体系费米能级的位置逐渐降低, 且电荷态为+2时, 含碳空位2×2×1 Ti₂CO₂超胞表现出半导体特性, 带隙类型转变为直接带隙, 带隙值为0.489 eV。     

Theoretical Analysis on the Measurement Errors of Local 2D DIC: Part II Assessment of Strain Errors of the Local Smoothing Method–Approaching an Answer to the Overlap Question

In this paper, the strain error of subset‐based two‐dimensional digital image correlation (DIC) is theoretically derived. Analytical solutions are provided to estimate the strain error. A dimensionless factor is proposed, namely the overlap magnifier, which reveals the dependency of the strain error on the DIC regularisation parameters, that is, subset size, step size and strain window size. The derived equations are validated numerically and experimentally. The estimated random strain error is in good accordance with the experimental data. The proposed derivation can be readily extended to stereo DIC.     

Enhancing the Humidity Sensitivity of Ga2O3/SnO2 Core/Shell Microribbon by Applying Mechanical Strain and Its Application as a Flexible Strain Sensor

The humidity sensitivity of a single β‐Ga₂O₃/amorphous SnO₂ core/shell microribbon on a flexible substrate is enhanced by the application of tensile strain and increases linearly with the strain. The strain‐induced enhancement originates from the increase in the effective surface area where water molecules are adsorbed. This strain dependence of humidity sensitivity can be used to monitor the external strain. The strain sensing of the microribbon device under various amounts of mechanical loading shows excellent reliability and reproducibility with a gauge factor of ?41. The flexible device has high potential to detect both humidity and strain at room temperature. These findings and the mechanism involved are expected to pave the way for new flexible strain and multifunctional sensors.