光栅码盘零位图案的CAD设计

根据增量式光学编码器对绝对零位信号的要求,建立了绝对零位光栅图案的数学模型,系统地提出了绝对零位光栅图案的设计理论,编制了计算机辅助设计程序,设计出用于工程的零位图案,并对零位图案的设计和性质及绝对零位信号进行了讨论.     

电子带宽对高速视频成像系统的限制

分析了高速视频成像系统的信息传递关系,从系统传递一定的信息量出发,得出其对电子系统带宽的要求;以靶场应用为对象,通过对满足测试需要的高速信息流量的分析计算,得出结论:在实际的电子线路和计算机处理技术的能力下,由于电子系统带宽的制约,高速视频成像尚不能完全取代传统的胶片式高速摄影系统.     

关于技术与数学教学整合现状的调查与思考

信息技术是当今社会的主要特征，它促使着各行各业产生翻天覆地的发展，教育中也是如此．与此同时，21世纪《数学课程标准》相对于以前的《教学大纲》适时的提出“把现代信息技术作为学生学习数学和解决问题的强有力的工具”，对现代信息技术进入数学课程领域采取了“大力开发”的策略．事实上，早在20世纪80年代，“计算机辅助教学”这个名词就在我国开始流行，但当时由于种种条件的限制，     

碳膜压阻传感器的静压加卸载标定

本文报告了对破膜压阻传感器进行的静压加载和卸载标定,量程范围为MPa-1.5GPa.文中介绍了实验方法,给出了四次标定曲线.     

压电材料中三维I型断裂力学分析

讨论了不可导通情况下三维横观各向同性压电材料中受拉伸和电载荷作用的平片裂纹I型断裂力学问题. 使用有限部积分概念，从三维线性压电理论出发，严格得到了一组以裂纹面位移间断和电势间断为未知变量的超奇异积分方程组；应用二维超奇异积分的主部分析法，从理论上分析得到了裂纹前沿应力和电势奇性指数以及应力和电位移奇性场，从而找到了以裂纹面位移间断和电势间断表示的应力和电位移强度因子、能量释放率表达式；为所得到的超奇异积分方程组建立了数值法，并用此计算了若干典型的平片裂纹问题，数值结果令人满意.     

水蚀性岩层中的渗流和无机污染物的迁移

介绍水蚀性岩层中的渗流及金属和无机污染物迁移问题．通过对含有污染物的某些蓄水系统中的物理和化学过程的分析得出一些结论，并对这些过程不仅作了详细的说明，而且采用恰当的数学和化学方程加以讨论．在水蚀性岩层中无机污染物的迁移用高渗透率多孔介质中流动的基本方程近似地描述，而对流、水动力学扩散、稀释等影响可作为物理过程来阐述．总的说来，控制裂隙岩体中地下水流动与污染物输运的物理和化学机理是建立水蚀性岩层中无机污染物输运近似方法的基础．     

Broad-band phase retrieval method for transient radial shearing interference using chirp Z transform technique

The transient radial shearing interferometry technique based on fast Fourier transform (FFT) provides a means for the measurement of the wavefront phase of transient light field. However, which factors affect the spatial bandwidth of the wavefront phase measurement of this technology and how to achieve high-precision measurement of the broad-band transient wavefront phase are problems that need to be studied further. To this end, a theoretical model of phase-retrieved bandwidth of radial shearing interferometry is established in this paper. The influence of the spatial carrier frequency and the calculation window on phase-retrieved bandwidth is analyzed, and the optimal carrier frequency and calculation window are obtained. On this basis, a broad-band transient radial shearing interference phase-retrieval method based on chirp Z transform (CZT) is proposed, and the corresponding algorithm is given. Through theoretical simulation, a known phase is used to generate the interferogram and it is retrieved by the traditional method and the proposed method respectively. The residual wavefront RMS of the traditional method is 0.146λ, and it is 0.037λ for the proposed method, which manifests an improvement of accuracy by an order of magnitude. At the same time, different levels of signal-to-noise ratios (SNRs) from 50 dB to 10 dB of the interferogram are simulated, and the RMS of the residual wavefront is from 0.040λ to 0.066λ. In terms of experiments, an experimental verification device based on a phase-only spatial light modulator is built, and the known phase on the modulator is retrieved from the actual interferogram. The RMS of the residual wavefront retrieved through FFT is 0.112λ, and it decreases to 0.035λ through CZT. The experimental results verify the effectiveness of the method proposed in this paper. Furthermore, the method can be used in other types of spatial carrier frequency interference, such as lateral shearing interference, rotational shearing interference, flipping shearing interference, and four-wave shearing interference.     

Theory of multiphoton photoemission disclosing excited states in conduction band of individual TiO2 nanoparticles

A theory of multiphoton photoemission is derived to explain the experimentally observed monotonic decrease with the wavelength in the electron yield of TiO₂ nanoparticles (NPs) by as large as four orders of magnitude. It is found that the fitting parameter corresponds to the energy position of Ti3d e_g and t_2g states, and the derived theory is a novel diagnostic of excited states in the conduction band, very importantly, applicable to individual NPs. The difference between four-photon slope NPs and three-photon slope NPs is attributed to the difference in defect density. The success of the theory in solving the puzzling result shows that thermal emission from high-lying levels may dominate over direct multiphoton ionization in solids when the photon number larger than four is required.     

虎克定律的一般形式 类电杨氏模量和类磁杨氏模量

原来形式的虎克定律 F=(Δl/l)AE 不满足于洛仑兹变换和力变换方程,这意味着虎克定律必须作修改,才能使它在洛仑兹变换下为不变.本文将弹性力与电磁力类比,提出了“类似洛仑兹力公式”形式的方程是改造虎克定律的可能途径.并通过力变换方程找到了虎克定律的一般形式,同时得到两个新的矢量“类电杨氏模量”和“类磁杨氏模量”.虎克定律的一般形式在低速(v<     

压电材料中三维I型断裂力学分析

讨论了不可导通情况下三维横观各向刚性压电材料中受拉伸和电载荷作用的平片裂纹Ⅰ型断裂力学问题．使用自限部分概念，从二维线性压电理论出发，严格得到了一组以裂纹面位移间断和电势间断为未知变量的超奇异积分方程组；应用二维超奇异积分的主部分析法，从理论上分析得到了裂纹前沿应力和电势奇性指数以及应力和电位移奇性场，从而找到了以裂纹面位移间断和电势间断表示的应力和电位移强度因子、能量释放率表达式；为所得到的超奇异积分方程组建立了数值法，并用此计算了若干典型的平片裂纹问题，数值结果令人满意．