Nuclear size and compressibility

Data on electron scattering on nuclei and spectra of mesoatoms and atoms are used to construct new expressions for nuclear size, which consider the effects of shells and deformations together with the dependence on A and Z. The compressibility of nuclei is also considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 84–89, November, 1982.     

Finite size effects of a pion matrix element

We investigate finite size effects of the pion matrix element of the non-singlet, twist-2 operator corresponding to the average momentum of non-singlet quark densities. Using the quenched approximation, they come out to be surprisingly large when compared to the finite size effects of the pion mass. As a consequence, simulations of corresponding nucleon matrix elements could be affected by finite size effects even stronger which could lead to serious systematic uncertainties in their evaluation.     

超薄镜的有限元分析

建立了组成空间望远镜主镜的超薄扇形子镜的有限元模型,分析了镜面的热变形和影响函数。通过对热变形的分析表明,为了减小空间温度场产生的镜面变形,应该选用具有一定弹性的面形致动器,或者致动器与镜面之间具有一定的相对滑动能力。通过对影响函数的分析表明:对所研究的弹性致动器来说,相邻致动器器之间具有明显的位移耦合,间隔致动器的耦合可以忽略;边缘致动器由于受到的约束比较小,在同样的致动伸长量下,产生的位移大于中心致动器。     

新型敏感器有限元动力学分析

介绍了一种超大口径、长焦距、折反式光学系统的新型敏感器。为验证其结构设计的可靠性和稳定性,使用大型通用有限元软件MSC Patran建立了整机有限元分析模型,用MSC Nastran对其进行了模态分析和随机振动分析。分析结果表明,星敏感器性能稳定可靠,可对一些关键部件的设计提供理论依据。     

Finite element dynamic analysis of practical discs

A semi-analytical annular finite element is developed for the dynamic analysis of non-rotating, rotating or pre-stressed discs having varying thickness in the radial direction. The element is based on the Mindlin thick plate theory. It has 2 nodes, 12 degrees of freedom, parabolic thickness, and is capable of representing all the geometric and natural boundary conditions of thick plates. The element is applied to the dynamic analysis of non-rotating and rotating uniform discs, and to practical turbine discs. The predicted natural frequencies of the discs are compared with analytical, experimental and other finite element solutions.     

Finite element analysis of nonsynchronous directional couplers

Abstract

An accurate vector finite element solution of the nonsynchronous directional coupler problem is presented, illustrating coupling lengths and supermodes of the complete structures.     

Finite element analysis of nonsynchronous directional couplers

An accurate vector finite element solution of the nonsynchronous directional coupler problem is presented, illustrating coupling lengths and supermodes of the complete structures.     

能动抛光磨盘的有限元法分析

 能动磨盘在光学抛光时随磨盘移动位置和旋转角度不同而产生不同的变形以实时与大口径被抛光工件表面实现良好的吻合。模拟了能动磨盘的工作过程，探讨了用于光学抛光的可行性。以加工直径1.5m，f1/2的抛物面光学元件为例，用有限元法对能动磨盘能够产生的变形进行了仿真计算，结果表明能动磨盘能够以较高精度产生旋转对称或非对称的二次曲面。     

大口径望远镜结构的有限元分析

望远镜是动态光电跟踪探测系统中的关键部件之一,特别是大口径光学系统,不仅要求主望远镜的稳定性高,还要尽可能地减少结构质量。根据1.3m大口径望远镜的结构设计方案,利用大型有限元结构分析软件I DEAS,采用板壳和质量单元描述结构主体,建立了较为精确的结构分析模型,求得了望远镜在不同俯仰角位置时的主、次镜位置变化,为整个望远镜的结构设计提供了可靠的依据。     

Stochastic finite element analysis of a vibrating string

The response of a vibrating string subjected to spatial white noise excitation is analyzed by using the finite element (Galerkin) method. The discretization is achieved by using basis functions in the spatial and random spaces. The continuous time finite element equations are then integrated in time by using the central difference algorithm. It is shown that when the string is divided into N segments, the Galerkin approach leads to N(N?1) degrees of freedom which are governed by N subsets of equations. The subsets are similar in form. Furthermore, for a uniform string, they are governed by the same operator as that which governs the system of (N?1) degrees of freedom arising from the corresponding deterministic problem. Random initial conditions can also be treated by the same method, and the analysis of strings with initial conditions described by the standard Brownian process is carried out. Numerical results are given to illustrate the stochastic response.     

Isogeometric finite element analysis of interior acoustic problems

Isogeometric Analysis (IGA) can bridge the gap between geometrical and numerical modeling. To this end, the same basis functions used in Computer Aided Design are applied to represent geometry and approximate physical field in analysis. In this paper, the IGA is firstly introduced to finite element method (FEM) for interior acoustic problems. The domain is parameterized by Non-Uniform Rational B-Spline (NURBS) in the algorithm, which simplifies the mesh generation greatly and furthermore supplies an exact representation of curved boundaries. In addition, the IGA FEM possesses a distinct feature of flexible order-elevation technique without modifying the geometry. Several numerical examples are presented to validate the accuracy and demonstrate the merits of the IGA FEM in the analysis of interior acoustic problems.     

Finite element dynamic analysis of practical bladed discs

The dynamic characteristics of one blade, two discs and one shrouded, bladed disc, having 87 blades, are predicted by the application of the finite element method of analysis. The discs are modelled by using both annular and sector elements. The blades are modelled by means of shell elements. The shrouds are represented by both lumped masses and straight beam elements. The predicted frequencies are compared with experimental results.     

双细胞光声信号的有限元分析

为了分析两个相同的细胞在不同距离下光声信号的特性,对细胞及环境进行了有限元分析。创建了不同距离的双细胞模型和相同环境下的单细胞模型,通过双细胞模型,得到了主体细胞在受到不同距离的另一个细胞的影响下,其不同角度的频域声压级曲线。通过单细胞模型,得到了单个细胞未受到影响时,其不同角度的频域声压级曲线。将主体细胞与单细胞频域声压级曲线进行相似度比较。结果表明,在受到不同距离的细胞影响下,主体细胞各角度的频域声压级曲线,存在与单细胞相似度极高的曲线,且距离为26.6微米时,相似度最高。这项研究表明,在两个双凹形红细胞距离适当时,细胞间的光声信号相互影响最小。     

ITER结构冷却馈线有限元分析

阐述了ITER结构冷却馈线的设计。运用有限元法对冷却馈线进行静力分析及地震分析,校核了馈线的应力及变形情况,验证了馈线结构设计的安全可靠性。     

ITER磁体支撑结构有限元分析

磁体支撑结构是国际热核聚变实验反应堆（ITER）的重要部件,对其进行力学特性分析研究是确保整个反应堆正常运行的关键。通过对磁体支撑结构各工况下的强度、刚度的数值分析,给出了磁体支撑结构对应工况下各零部件的应力分布及变形量;分析结果表明磁体支撑结构各零部件的最大应力值均小于许用应力,满足强度要求,各零部件变形合理,不会出现脱开失稳现象。通过数值分析,为国际热核反应堆磁体支撑结构提供了理论设计数据,提升了磁体支撑结构的安全性和可靠性。     

ITER磁体支撑结构有限元分析

磁体支撑结构是国际热核聚变实验反应堆(ITER)的重要部件,对其进行力学特性分析研究是确保整个反应堆正常运行的关键。通过对磁体支撑结构各工况下的强度、刚度的数值分析,给出了磁体支撑结构对应工况下各零部件的应力分布及变形量;分析结果表明磁体支撑结构各零部件的最大应力值均小于许用应力,满足强度要求,各零部件变形合理,不会出现脱开失稳现象。通过数值分析,为国际热核反应堆磁体支撑结构提供了理论设计数据,提升了磁体支撑结构的安全性和可靠性。     

大口径光学元件环境热稳定性的有限元分析

讨论了靶场光学元件在环境热载荷作用下的变形分析理论和数学描述,采用有限元分析软件ANSYS建立了靶场反射镜的模型,用靶场实测环境温度变化作为载荷,计算得到了反射镜在靶场温度变化0.3 ℃时,垂直镜面方向的变形及其在平行于镜面平面内的转角漂移。结果表明：在当前的温控条件下,光学元件在环境热载荷作用下的变形满足稳定性设计要求。并计算了几种环境温度变化下反射镜的变形和转角漂移。初步的结果表明：环境温度变化与反射镜的转角漂移成正比。