空气中微波击穿电场的计算

本文采用扩散控制的微波击穿模型,计算了低气压空气的微波击穿电场.为获得简单而直观的计算方法,利用了直流场中的气体放电基本参量,给出了微波击穿电场的计算过程.通过合理的数学处理,推导出计算微波击穿电场的简单公式.计算结果显示,微波击穿电场与气压的关系呈现出典型的帕邢曲线,即在某个气压时击穿电场最小.最低击穿电场及其对应的气压,也以简单公式的形式在文中给出.用简单公式计算出的击穿电场与文献的实验结果基本符合,表明简单公式是正确的.在此基础上,探讨了影响击穿电场的因素.结果表明,等效直流电场和电子平均温度均与微波频率无关,它们均是气压与特征扩散长度乘积的函数.微波击穿电场并不是气压与特征扩散长度乘积的函数,而是分别受气压、微波频率、特征扩散长度的影响.频率越高,击穿电场越大.特征扩散长度越大,击穿场强越小.     

多间隙休斯结构耦合腔轴向电场分布的解析计算

在考虑相邻谐振腔间耦合作用对电场分布影响的基础上,分析了多间隙休斯结构耦合腔中存在模式电场分布的特点,采用双曲正割函数拟合代替传统无耦合单间隙腔中电场分布计算的高斯函数拟合,构建了多间隙耦合腔轴向电场分布函数计算的解析表达式。经不同几何参数和间隙数目耦合腔的仿真验证,电场分布解析计算结果与CST-MWS仿真结果具有好的一致性,对分布作用速调管注波互作用模拟和工程研制有益。     

粉体料仓灌充期间仓内电场模型研究

提出了圆柱形接地粉体料仓灌充期间仓内电场计算模型，为计算电场分布和安全评价提供理论基础。     

探针的近场分布特性研究

采用三维时域有限差分法对锥形镀金属膜光纤探针出射端口处的电场进行计算,计算结果显示,出射光在探针尖端出现退极化现象,产生与入射光偏振方向垂直的两个电场分量,对探针的纵向截面中,与入射偏振光垂直的截面和与入射偏振光平行的截面上的电场分布进行计算与比较。     

水下物体对船舶电场的扰动分析

讨论了海洋船舶腐蚀引起的静电场的基本模型，对Galvanic System电场在水中兵器，电场测量体等实体附近可能产生的电场畸变进行了分析计算，理论计算表明；雷体等水下实体对电场的扰动的大小主要取决于雷体与舰船的距离，雷体材料的电阻率，雷体的尺寸，当距离大于10m时，其引起的电场畸变的相对变化率小于2%，由此得出了利用舰船电场远场作为启动信号时可以不考虑电场扰动的结论。     

纳米管场发射的电场计算

利用电磁场理论计算出单根纳米管场发射时其尖端附近的电势和电场分布。结果表明 ,纳米管尖端表面电场非常强 ,随着距离尖端表面的距离的增加 ,电场迅速下降 ;尖端附近的场强与纳米管场发射有低的阈值电压相符合。计算还给出在保持极板间距离和电压不变的情况下 ,纳米管长径比越大 ,尖端电场越强 ,因此 ,具有更低的阈值电压     

电场数值计算的常用方法

电场的数值计算在工程中有很大的应用价值,为此介绍了3种常用的电场数值计算方法:模拟电荷法、有限差分法、有限元法。主要分析和比较了三种方法的原理、解题步骤和优缺点,三种方法的适用场合略有差别,指出了有限元法是比较适合实际工程计算电场的方法。     

盒栅式倍增系统打拿极三维电场模拟计算

利用ANSYS软件对盒栅式倍增系统打拿极三维电场分布进行了建模,计算了打拿极附近电势分布情况。通过对比不同模型的计算结果,对影响盒栅式倍增系统打拿极电场分布的因素进行了研究。结果表明,打拿极的结构布局和栅网宽度对电场分布的影响较大。     

海水中稳恒电流电场的点电极计算模型

根据点电极基本假设，利用均匀介质中稳恒电流场与静电场的相似性，分别采用分离变量法和镜像法计算了点电极稳恒电流场在空气-海水-海床三层介质平行界面模型下的电位分布。从而得到了海水中稳恒电流电场的计算模型．计算结果表明：点电极的电场分布具有明显的特征，可作为舰船电场电极阵列模拟的计算单元。     

基于微扰理论的静电电子透镜的缺陷电场计算

研究了用于计算光学系统的缺陷电场和容差的微扰理论。基于微扰原理，推导了计算静电电子透镜电子电极偏心，倾斜和加工不圆造成的电场变化及其旁轴多极场展开函数的九点有限差分公式，邮计算软件。建立了两个电场解析模型、通过该模型和解析解与数值计算结果的对比，证实了算法及软件的正确性，并据此讨论了微扰理论用于容差计算的适用范围。     

Recent improvements to the application of the volume integral method of eddy current modeling

A previous attempt by Dunbar to model eddy current NDE data using the volume integral equation method produced qualitative agreement with experimental data, but true verification was not possible due to the fact that the results were not independent of the discretization of the flaw and there were numerical problems encountered in calculating the unperturbed electric field. We have overcome these problems by calculating the integrals of the Green's tensor more accurately, especially in the vicinity of any singularities, and by using a fast Hankel transform to calculate the incident electric field. Further improvements were made by considering a linear variation of the electric field, instead of taking it to be constant over each cell used in the discretization. Results obtained from rectangular flaws in a half-space and in a thin plate are presented.     

含压电片复合材料层合板的高阶计算模型

给出了一种分析含任意内埋压电片复合材料层合板的高阶耦合模型, 板的位移场采用三阶剪切理论, 并提出了压电片中电势场在厚度方向的三次分布模式, 可以更精确地描述力、电耦合作用下电场的非均匀分布。在平面应力的假设下给出了简化的压电材料本构方程, 推导了基于该模型的压电层合板有限元计算公式, 并对双压电片梁的弯曲和层合板的变形控制进行了计算, 压电梁的弯曲计算结果与解析结果吻合良好, 表明本文的模型和公式是精确有效的。     

Characteristics of the motion and distribution of the solid phase in a jet discharging into a fluidized bed

A model of the motion of the solid phase from the bed into a jet is proposed. A method for calculating the velocity field and solid-particle concentration field in the volume of the jet is developed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 51, No. 3, pp. 436–443, September, 1986.     

差压式流量计测量脉动流量方法研究

利用脉动流动工况下差压式流量计理论模型,给出了通过双路差压计算瞬时脉动流量的算法,并利用FLUENT软件对文丘里管内流场进行仿真计算,对脉动流量计算方法进行验证。仿真结果表明,单路压差计算脉动流量,由于遗漏流量导数项可产生很大测量误差,最大误差甚至可达100%;而通过双路差压计算脉动流量,可有效消除流量导数项影响,算例中最大误差降低至5%左右。     

Density distribution of a binary liquid in a cylindrical pore under the action of external field

We solve the problem of calculating the density distribution of binary liquid components in a cylindrical pore under the action of external field. The problem is solved in the slow inhomogeneity approximation based on a phenomenological expression for the free energy of the studied system. Taking into account the expression for the general solution, we separately analyze the case of a gravitational field. We also examine the particular case of a WR-type model system.     

Temperature distribution in a composite rod with a step change in the conditions of heat transfer

A method is proposed for calculating the steady-state temperature field of a model pipe fitting. The results are compared with test data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 5, pp. 884–889, November, 1972.     

Modeling of the temperature field of the casting ladle lining

We propose a method for calculating the temperature field of the casting ladle lining by a modified relaxation method. Given such initial data as the metal temperature in the ladle, the ambient temperature, and the lining structure, this method permits calculating the stationary temperature fields both inside the lining and on the surface of the ladle jacket. The model was tested by comparing experimentally measured temperature values on the surface of the ladle jacket with calculated temperatures. A satisfactory agreement between calculated and experimental temperature values of the ladle surface has been obtained.     

Far-field interference from a sphere and its applications

A theoretical model of far-field interference from a sphere has been established, and its applications have been investigated. When two coherent parallel laser beams shine on a smooth sphere surface from opposite directions, the reflected lights form interference fringes at far field. The fringes have hyperbolic shapes and are not uniformly distributed. This paper derives a method for calculating the path-length difference between two parallel reflected lights, analyzes the interference field, and discusses reasons that cause the fringe density variations. A formula for calculating the highest orders of interference fringes is also provided. A method for using a spectrometer, CCD camera, and computer to measure the sphere diameter is demonstrated. The results agree with those from an Abbe comparator. The theory and methods are also suitable for measuring diameters of smooth cylinders.     

Using magnetic birefringence to determine the molecular arrangement of supramolecular nanostructures

Supramolecular aggregates can be aligned in solution using a magnetic field. Because of the optical anisotropy of the molecular building blocks, the alignment results in an anisotropic refractive index of the solution parallel and perpendicular to the magnetic field. We present a model for calculating the magnetic birefringence, using solely the magnetic susceptibilities and optical polarizabilities of the molecules, for any molecular arrangement. We demonstrate that magnetic birefringence is a very sensitive tool for determining the molecular organization within supramolecular aggregates.     

Radiative-conductive heat transfer in a semitransparent composite with microspherical particles

A mathematical model for calculating the temperature field in a semitransparent composite material that includes a polymethyl methacrylate matrix and quartz microspheres is suggested. In calculating the optical properties of the composite material, use was made of the optical properties of the matrix and of the interacting quartz microspheres at different filling factors which characterize the volume concentration of particles in the matrix. Allowance for the interaction between the composite components is made following the Maxwell–Garnett approximation. Data on the complex refractive index of the composite were used for calculating the coefficients of absorption, scattering, and attenuation of packed particles by the Mie theory. The temperature fields in a layer of the material are found from solving the boundary-value problem for the energy equation and a system of radiation transfer equations with the use of these coefficients.