The Effect of Mechanical Force on Generalized Thermoelasticity in a Fiber-Reinforcement Under Three Theories

The present paper is concerned with effect of mechanical force on generalized thermoelasticity in a fiber-reinforcement. The formulation is applied to generalized thermoelasticity based on the coupled theory, Lord–Shulman theory, and Green–Lindsay theory. The analytical expression of the displacement components, stresses, and temperature are obtained in the physical domain and illustrated graphically using normal mode analysis. Comparisons are made among the three theories for the field quantities in the absence and in the presence of a fiber-reinforcement as well as for different values of mechanical force.     

圆弧形层状凹陷地形对平面SH波的散射

利用Fourier—Bessel级数展开法给出了圆弧形层状凹陷地形对平面SH波散射二维问题的一个解析解，分析了层状凹陷地形沉积排列顺序、软夹层刚度和厚度等因素对SH波散射的影响。结果表明，层状凹陷地形对平面SH波的散射和单一凹陷地形差别很大，凹陷地形表面松软沉积的存在，即使厚度很薄，也会大大降低凹陷地形本身对入射波的屏障作用；层状凹陷地形中沉积排列顺序、软夹层刚度和厚度的变化对散射也具有重要影响。     

Reflection of Plane Waves in a Semiconducting Medium under Photothermal Theory

In this paper photothermal theory was used to study the reflection of waves at the surface of a semi-infinite semiconconducting medium. Using the harmonic wave method, the reflection coefficient ratios were obtained analytically under coupled thermoelastic theory and plasma theory for an incident CI wave, which is one coupled thermoelastic plasma wave and an incident rotational wave. The variations of the amplitude of reflection coefficient ratios with the angle of incidence are shown graphically for silicon. Effects of the thermal frequency, the thermoelastic coupling parameter, and the thermoelectric coupling parameter were given by numerical results. Also, the energy ratios for reflected waves were computed to check the numerical results.     

Optical Diffraction in Close Proximity to Plane Apertures. II. Comparison of Half-Plane Diffraction Theories

The accuracy and physical significance of the classical Rayleigh-Sommerfeld and Kirchhoff diffraction integrals are assessed in the context of Sommerfeld’s rigorous theory of half-plane diffraction and Maxwell’s equations. It is shown that the Rayleigh-Sommerfeld integrals are in satisfactory agreement with Sommerfeld’s theory in most of the positive near zone, except at sub-wavelength distances from the screen. On account of the bidirectional nature of diffraction by metallic screens the Rayleigh-Sommerfeld integrals themselves cannot be used for irradiance calculations, but must first be resolved into their forward and reverse components and it is found that Kirchhoff’s integral is the appropriate measure of the forward irradiance. Because of the inadequate boundary conditions assumed in their derivation the Rayleigh-Sommerfeld and Kirchhoff integrals do not correctly describe the flow of energy through the aperture.     

从平面走向立体(上)

印刷品的三维设计,也称立体设计。英文原文为Three-Dimensional Design,简称3D设计。传统的印刷品有招贴广告、户外广告、报纸广告、杂志广告、书籍设计、样本等形式,以平面形式为多。而三度空间的纸质印刷品设计不失为一种新的形式,它不但形式活泼、生动有趣,且较有效地配合了内容。常见的典型设计作品有立体书、立体贺卡等。本文的作者曾在英国中英格大学攻读视觉传达设计硕士学位,主攻方向为立体书设计,研究成果颇为丰厚。这里选登的是作者关于3D设计研究的部分成果。本刊下期将作连续报道,以飨读者。     

A Comparison of Three Different Procedures for Estimating Variance Components

An analytic procedure for obtaining variances of estimates of variance components in a general multi-way classification is described. As an application, three methods for estimating variance components are compared for a two-way classification. Since the variances of the estimates are affected by the magnitude of the true variance components (parameters) as well as the arrangement of the subclass numbers (n _ij 's), a numerical tabulation is necessary in order to make a comparison. Using a UNIVAC 1105, the variances of the estimates of variance components are evaluated over a substantial range of parameters and n _ij 's. These results are presented in tabular form for selected sets of parameter values.     

Two-Temperature Effects on Plane Waves in Generalized Thermo-Microstretch Elastic Solid

In this article, the effect of two temperatures on plane waves propagating through a generalized-thermo-microstretch elastic half-space solid has been investigated. The surface of the medium is subjected to a mode-I crack, and the $z$ axis is pointing vertically into the medium. Two fascinating theories of generalized thermo-elasticity presented by Green and Naghdi and named as without energy dissipation (GN-II) and with energy dissipation (GN-III) have been used. Governing equations for each particular case are also derived, and a solution is obtained. An analytical technique of normal mode analysis is used to obtain the exact expressions for the displacement components, force stresses, the temperature, and the couple stresses distribution. The variations of the considered variables against the vertical distance are illustrated graphically. Comparisons are made with the results between type II and III in generalized-thermo-microstretch and in a particular case (without microstretch constants). Numerical work is also performed for a suitable material with the aim of illustrating the results. It is found that the maximum amplitude is obtained for the maximum value of the two temperature parametric constant.     

Magneto-thermoelastic Response in a Functionally Graded Isotropic Unbounded Medium Under a Periodically Varying Heat Source

This paper deals with the problem of magneto-thermoelastic interactions in a functionally graded isotropic unbounded medium due to the presence of periodically varying heat sources in the context of linear theory of generalized thermoelasticity with energy dissipation (TEWED) and without energy dissipation (TEWOED) having a finite conductivity. The governing equations of generalized thermoelasticity (GN model) for a functionally graded material (FGM) under the influence of a magnetic field are established. The Laplace–Fourier double transform technique has been used to get the solution. The inversion of the Fourier transform has been done by using residual calculus, where poles of the integrand are obtained numerically in a complex domain by using Leguerre’s method and the inversion of the Laplace transformation is done numerically using a method based on a Fourier series expansion technique. Numerical estimates of the displacement, temperature, stress, and strain are obtained for a hypothetical material. The solution to the analogous problem for homogeneous isotropic materials is obtained by taking a suitable non-homogeneous parameter. Finally, the results obtained are presented graphically to show the effect of a non-homogeneous, magnetic field and damping coefficient on displacement, temperature, stress, and strain.     

关系营销理论探讨--三种理论的区别和联系

关系营销是一种新型的营销理论，它是随着经济技术的发展和竞争的日益激烈而逐步发展起来的。对于关系营销不同角度的研究形成了不同的理论学派。本文介绍了在关系营销研究中具有代表性的三种理论学派，即承诺－信任理论、六市场模型和关系、网络、互动理论，指出这三种理论是从不同的层面研究关系营销的，尽管其研究角度不同，但是理论之间存在着一定的联系。认识到这一点，对于企业营销管理的研究实践活动具有重要的意义。     

Reflection and Transmission of Plane Waves at the Planar Interface of a General Uniaxial Medium and Free Space

Abstract

A general uniaxial medium is characterized by its permittivity and permeability tensors having the same preferred axis. The plane wave reflection and transmission characteristics of a planar interface between free space and a general uniaxial medium have been obtained; since application as a polarizer is envisioned, the preferred axis lies in a plane parallel to the interface. Application of the Brewster law, as well as conditions for total reflection are explored.     

三种不同方法测定室内空气中甲醛含量的比较

目的:用酚试剂分光光度法、乙酰丙酮分光光度法和4-氨基-3-联氨-5-巯基-1,2,4-三氮杂茂(AHMT)分光光度法三种方法测定空气中甲醛,通过比较测得的甲醛数据,找出3种方法优劣.方法:用5 mL蒸馏水作为吸收液采样空气样,取(1～5)mL样量按三种方法分别检测出5mL吸收液中甲醛量,再除以采样体积,计算出空气中甲醛浓度.结果:三种方法线性关系良好,相关系数均大于0.9990,BY400160标准水样用三种方法测定的甲醛结果为酚试剂法1.49mg/L,乙酰丙酮法1.50mg/L,AHMT法1.51mg/L,标准水样参考值(1.49±0.07)mg/L.三种方法的相对标准偏差:酚试剂分光光主法(2.23～3.83)％,乙酰丙酮分光度法(1.64～2.84)％,AHMT分光光度法(3.80～4.36)％.结论:三种方法的线性宽、灵敏度好、检出限低、精密度和准确度令人满意,能精准测定室内空气中甲醛.     

The Effect of Gravity on Plane Waves in a Rotating Thermo-Microstretch Elastic Solid for a Mode-I Crack with Energy Dissipation

The present article is aimed at studying the effect of gravity on the general model of the equations of generalized thermo-microstretch for a homogeneous isotropic elastic half-space solid rotating about the fixed axis of rotation and whose surface is subjected to a Mode-I crack problem considered. The problem is in the context of the Green and Naghdi theory (GN). The normal mode analysis is used to obtain the exact expressions for the displacement components, force stresses, temperature, couple stresses, and microstress distribution. The variations of the considered variables perpendicular to the axis of rotation are illustrated graphically. Comparisons are made with the results in the presence and absence of gravity and rotational frequency of a particular case for the generalized micropolar thermoelasticity elastic medium (without microstretch constants) between the two types (II, III).     

A Comparison of Diffraction Theories for Off-bragg Replay

Two first-order analytic solutions and a second-order analytic solution for the case of lossless-dielectric unslanted volume transmission gratings are compared for the case of weak grating index modulation and significantly off-Bragg replay. It is shown that the analytic solution predicted using the Beta-value method, which has previously been found to agree more closely with experimental results for the unslanted case than the first-order K -vector closure method (of Kogelnik), also agrees more closely with the analytic expression produced by the second-order coupled-mode equations of Kong for this case. A numerical comparison of the first order theories and the rigorous coupled wave theory gives a similar result. Thus the Beta-value method offers definite advantages over the Kogelnik K -vector closure method for the unslanted transmission geometry.     

Modelling and Analysis of Power Distribution of Electromagnetic Waves on Plane Surfaces Using Lock-in IR Thermography

The electric field distribution (magnitude only) near a radiating source (antenna) can be easily determined using infrared thermography. A thin screen (made of carbon fiber reinforced polymers) is placed in front of a microwave source. The electromagnetic waves impinging on the screen are partially absorbed, resulting in temperature rise of the screen. This temperature rise is monitored by an infrared camera. The temperature distribution thus observed is mapped to the electric field strength (magnitude of electric field) of the electromagnetic waves. Points on the screen where the temperature rise is low correspond to weak electromagnetic fields whereas points with high temperature rise correspond to strong electromagnetic fields. In this paper electro-thermal modelling is done so as to obtain the temperature distribution over the screen, when an electromagnetic field is incident on it. This model can conversely be used for finding electromagnetic field distributions from IR thermal images.     

On the Possibility of Monitoring of Adhesive Joints of Bodies by Sounding with Plane Transverse Electric Waves

The reflection factor is analytically determined for a plane transverse electric wave reflected from an adhesive joint of a plate with a semiinfinite body in the presence of an intermediate layer whose dielectric permittivity linearly varies over the thickness of the layer. By analyzing the quantitative frequency dependences of the reflection factor for the investigated object, we conclude that the intermediate layer can be detected and its thickness can be approximately evaluated by comparing the theoretical results with the experimental data on sounding with 3–5-mm waves.__________Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 1, pp. 89–92, January–February, 2005.     

Comparison of the Griffith and Irwin Criteria for a Crack Asymmetrically Propagating in the Plane

On the basis of asymptotic formulas for the stress intensity factors and strain energy and the variational formulations of the Griffith and Irwin criteria, we propose asymptotic models of quasistatic crack growth. Under certain conditions, the transition to asymptotic models violates the equivalence of these criteria typical of the complete variational formulations. This phenomenon is analyzed and explained for a specific problem of asymmetric growth of a rectilinear crack in the elastic plane used as an example.     

成纤维细胞预处理过程及三种低温保存方法比较的实验研究

成纤维细胞是构建组织工程化真皮的种子细胞,实现成纤维细胞的低温保存对成功保存组织工程化真皮有着重要的意义.采用三种不同的低温保存方法对成纤维细胞进行低温保存实验;详细介绍这三种方法的操作过程;并从细胞存活率、降温过程中的温度变化情况、操作时所需仪器设备及所耗时间等方面对这三种方法进行了比较.同时研究了DMSO的浓度、预处理时间及预处理温度等因素对成纤维细胞存活率的影响.     

3种亚像素位移测量算法的比较研究

梯度法、曲面拟合法和N-R法是数字散斑相关方法中提高位移测量精度的3种主要亚像素位移算法。研究了3种算法的原理并进行了数值模拟仿真。首先使用计算机模拟生成一系列位移为0.01 pixel的散斑图,并在生成的图像中添加方差不同的高斯噪声,对3种算法在噪声条件下的精度进行比较,结果显示在精度要求为0.01 pixel时,梯度法的噪声方差上限为0.006,N-R法的噪声方差上限为0.000 5,而曲面拟合法的计算精度具有较大不确定性,无法保证精度,梯度法更适用于工程应用。