新型光学元件

介绍了近几年来在光电仪器中开始使用的新型光学元件,它们是衍射元件与衍射折射混合元件,溶胶－ 凝胶法高纯度特殊元件和微光学元件,轴向梯度元件以及玻璃－ 液体组合元件等。介绍了它们的应用和制造方法。这些元件给光学系统设计提供了新的自由度,并大大地简化了系统的结构和减小了系统的尺寸。     

全息光学元件递推制作的数学模型

用递推制作方法可制作出像质优良的全息光学元件。首先用球面光路系统产生球面参考波,制作一块中间全息元件,然后用这块中间全息元件产生非球面参考波,制作出最终全息元件。本文阐述全息光学元件递推制作的数学摸型。     

基于单一元件产生太赫兹无衍射波束技术研究

提出了一种新型的光学元件,可以产生与元件具有一定距离的无衍射波束。普通轴棱锥的横截面为等腰三角形,通过在两个腰上限定抛物线进行元件设计,采用3D打印技术制作了不同结构参数的光学元件。角谱理论的仿真计算结果以及在0.1 THz频率下进行的实验结果,都清晰地表明了产生的无衍射波束与元件之间具有一定距离。利用空间频谱对元件的波束行为进行分析,结果表明,该元件产生了一种新型的无衍射波束,根据元件的空频形状,将元件产生的无衍射波束命名为“梳状空频无衍射波束”。     

基于场协同原理的聚合物塑化过程数值分析

本文采用数值计算方法分析了挤出机不同螺杆塑化系统的流动与传热特性,并且提出了一种新型螺杆元件——扭转元件。结果表明,相对于普通螺纹元件,配置有扭转元件的螺杆具有更好的温度均匀性和传热性能。扭转元件中非牛顿黏弹性流体的强化传热的机理可以用场协同理论进行解释,即扭转元件的温度梯度场与速度场的协同性更好,努塞尔数更高,对流换热性能更好。     

胶粘光学元件的热应力和变形分析

由于光学元件和装配材料热膨胀系数的不匹配,在环境温度变化时会导致光学元件中产生热应力,并引起光学元件表面产生变形,影响光学系统的性能.针对光学元件的粘接固定方式讨论了连续边缘粘接引起的热应力和变形的分析方程,得出连续边缘粘接无热厚度的解析方程.采用有限元分析软件对胶粘固定光学元件进行了建模和热应力分析,得出光学元件边界...     

全息光学元件

全息光学元件是一种有别于经典光学元件(反射或折射型)的衍射光学元件[1,2].由于它是薄膜型光学元件,因此有重量轻、性能可靠、制造方便、成本低等特点.它特别适用于“准单色光系统”和激光系统.如果全息光学元件与经典光学元件相结合,还能扩展和改善光学系统的性能和应用范围.     

二元光学元件

二元光学元件是一种新型的衍射光学元件,它对光学仪器的小型化、集成化起着很重要的作用。本文介绍了二元光学元件的概况,衍射透镜理论,二元光学元件的制造方法以及发展趋势。     

磁流变抛光入口区域剪切力场形成机制数值分析

平面光学元件的浸入深度、凸球面光学元件的浸入深度、凸球面光学元件的曲率半径不同会使磁流变抛光入口区域剪切力场发生变化.为了研究磁流变抛光入口区域剪切力场的形成机制,建立磁流变抛光过程中必要的流体模型,对入口区域的几何特征进行分析;通过数值计算平面光学元件不同浸入深度、凸球面光学元件不同浸入深度、凸球面光学元件不同曲率半...     

基于双波长数字全息术的微光学元件折射率分布及面形测量

提出了一种测量微光学元件的折射率分布及面形的方法。该方法基于双波长数字全息术,将微光学元件浸入折射率匹配液降低通过微光学元件的透射光波频率,获取微光学元件在两个不同波长照明光波下的数字全息图,并根据两个波长下的相位分布,计算出微光学元件的折射率分布,利用得到的折射率分布获取微光学元件的面形。理论分析及实验结果证明了所提方法的可行性。     

不同结构光栅的衍射光强分布

构造了不同折射率介质组成的透光元件A及元件A组成的光栅,并计算平行光垂直透过元件A及元件A组成的光栅时衍射光强的分布,通过实验演示了一些不同结构光栅的衍射光强分布.     

A general finite element model for numerical simulation of structure dynamics

A finite element model used to simulate the dynamics with continuum and discontinuum is presented. This new approach is conducted by constructing the general contact model. The conventional discrete element is treated as a standard finite element with one node in this new method. The one-node element has the same features as other finite elements, such as element stress and strain. Thus, a general finite element model that is consistent with the existed finite element model is set up. This new model is simple in mathematical concept and is straightforward to be combined into the existing standard finite element code. Numerical example demonstrates that this new approach is more effective to perform the dynamic process analysis in which the interactions among a large number of discrete bodies and continuum objects are included.     

内标法在土壤重金属镍元素X荧光分析中的应用研究

利用能量色散型XRF重金属实验平台,在实验室自然大气环境下获取土壤的X射线荧光,通过X射线荧光光谱法定量分析了国家标准土壤样品中元素Ni的含量。实验研究了土壤中Ni元素的X荧光特征分析谱线,采用加入内标法测定了Ni元素定标曲线,并依据实验结果分析了内标元素选取方法。实验结果表明,对土壤样品进行内标法分析时,可选取基体中适宜元素作为内标元素;使用Pb的Lα线,Cu和Fe的Kα线作内标线时相对标准偏差(RSD)分别为6.24%,5.24%和5.22%,说明选择合适基体主量元素的特征谱线作为内标线,可有效提高测量结果的准确性。     

Stresses in shell structures

In this paper the stresses obtained for various (thin) shell structures by using two types of doubly curved finite elements are compared with published information. One of the elements—a ring shell element—is designed to analyze axisymmetric structures such as cylinders and hyperboloids. The accuracy and convergence of this element is shown to be excellent. The other element—a quadrilateral shell element—is designed to calculate stresses, mode shapes and frequencies of axisymmetric structures as well as sections of shell structures. The quadrilateral element is more versatile than the ring element. However, it is found that the convergence of the ring element is superior to that of the quadrilateral element. The resonant stresses of a hyperboloidal shell structure have been presented, and, as far as the author is aware, a similar investigation has not previously been reported in the literature. Whilst the primary purpose of the paper is to examine the usefulness of the two doubly curved elements in the analysis of shell structures, the examples considered in the text are described in detail to facilitate comparative structures by future investigators.     

冷熔合反应合成超重元素的进展

综述了自提出冷熔合反应作为合成原子序数 Z>1 0 6号超重元素的最主要反应机制以来 ,冷熔合合成超重元素所取得的重大成就及其进展至目前所面临的困惑 .详细介绍了最近国际上围绕 1 1 8号元素合成以及对以冷熔合反应合成 Z>1 1 2号超重元素前景上的争论 .讨论了在我国现有实验条件下 ,基于冷熔合机制开展超重元素合成面临的问题. The great successes of cold fusion reaction which was suggested as the most important production mechanism for superheavy element of Z >106, as the well as the main hot point problems in recent research of superheavy element synthesis are reviewed. Some different opinions around the synthesis of the superheavy element of Z =118 and the further prospect of utilizing cold fusion reactions to the syntheses of superheavy elements of Z >112 are introduced in detail...     

基于改进Stoilov算法光学元件瑕疵检测

提出一种基于统计逼近的改进Stoilov算法,可以除去光学元件检测中展开相位时遇到的奇异点和超大误差,提高测量精度。通过重构瑕疵表面3维形貌,并对规则几何形状光学元件表面进行拟合,建立光学元件瑕疵检测理论模型,可以有效对光学元件表面瑕疵进行检测。把该算法和模型运用到光学平晶瑕疵检测中,测出光学平晶的微小划痕深度为40nm。     

基于对偶混合变分原理的Signorini问题的数值模拟

基于Signorini问题的对偶混合变分形式,提出了一种非协调有限元逼近格式,证明了离散的B-B条件,获得了Raviart-Thomas(k=0)有限元逼近的误差界O(h^3/4),并且Uzawa型算法对协调与非协调有限元逼近格式进行了数值求解.根据数值结果的分析和比较,表明应用非协调有限元逼近格式求解更有效.     

宽带W波段Flaps天线仿真与设计

设计了一种结合了"十"字和圆环的新型宽带W波段Flaps(Flat Parabolic Surface antenna)天线单元。相比于传统的单层Flaps天线单元,新型单元能获得更宽的相位范围且相移精度更高,能有效拓展天线的带宽。利用这种单元设计了94 GHz的单层Flaps天线,仿真结果显示了较好的带宽性能和方向性,中心频率处增益18.2 dBi,在10.6%的带宽内增益下降小于1 dB,实现了较好的宽带性能,为单层W波段Flaps天线的设计提供了一种新途径。     

C~0 and C~1 theories and test functions for FEM patch test in microstructures

Among many theories and categories in microstructures,rotation-displacement used as "independent" or "dependent" variables,is a noticeable topic. In FEM,it is called C0 and C1 theory. The convergence criteria of finite elements for microstructures are less mature than those for the conventional thin plate bending problem. In this paper,the patch test functions for assessing convergence of the C0 and C1 finite elements in microstructures is established based on the enhanced patch test theory. The author has further explored the C0 and C1 finite element theories and investigated the difference and correlation between their finite element formulations. Newly proposed finite element theories for microstructures are as follows:(1) the displacement-rotation dependent C1 element that requires the element function satisfying both C0 and C1 continuity;(2) the displacement-rotation independent C0 element which requires new convergence criteria,such as non-zero constant shear stress patch test and zero constant shear stress patch test for approximating C1 element.     

Classification of Bianchi cosmologies in conformal flat space-times

There exist nine types of Bianchi cosmologies classified according to the structure constants of the corresponding Lie groups. Each of these types gives rise to a particular form of the line element, the Friedmann universe corresponding to the simplest type I. It is also known that there exists a simple correspondence (transformation) between the Robertson-Walker line element and the conformal line element but restricting the arbitrary function of that line element. This suggests that a classification of conformai flat line elements according to their parameters should yield a classification similar to that of Bianchi. The conformal group has 15 parameters, corresponding to the pure conformal group, Lorentz group, translation, and dilation. A classification of the line element according to these has been carried out, singly and combining several of them. It has been found that the Friedmann universe is a subclass, as expected, with other cosmologies resulting as wider subclasses. Comparison with the Bianchi classification is also made.     

Improvement of efficiency of piezoelectric element attached to beam based on mechanical impedance matching

This paper describes new methods that improve the efficiency of a piezoelectric element attached to a beam based on mechanical impedance matching. Piezoelectric elements are often used to suppress bending vibration. They are also used as sensors or energy-harvesting sources. In such cases, the piezoelectric element is usually bonded onto the host structure by an adhesive bond. The efficiency of the piezoelectric element depends on the bonding location. When the efficiency is insufficient despite a good location, the size or number of piezoelectric elements is increased. However, the efficiency of the piezoelectric element is usually insufficient even if these methods are applied. In order to enhance the efficiency of the piezoelectric elements without using active methods, this paper proposes a mechanical impedance matching method that uses spacers or tuning for the size of the piezoelectric element. Because the attached piezoelectric element and host structure in this region behave as springs in parallel to the bending deformation, the stored strain energy in the piezoelectric element is maximized under the condition that their spring constants match. The proposed methods were theoretically investigated with consideration for the effects of the bonding layer, spacers, and host structure. The optimum conditions for the proposed methods were theoretically formulated, and the effectiveness of the proposed methods and theoretical analysis was verified through simulations and experiments.