关于《普通物理学思考题题解》一书中几个题解的评注

本文对上海科技文献出版社出版的《普 通物理思考题题解》一书中的几个问题提出批 评性的评注，评注的几个力学问题都属于普通 物理学最基本的概念问题．评注中力求突出物 理概念，讲究思维方法．     

提高普物运动学讲授的起点

为了避免与中学物理运动学教材体系上的“重复”，本文在直角坐标系的范围内对普物运动学方程采用矢量形式的分析和计算，并给出了相应的物理内涵分析．以使普物运动学的讲授内容和使用的数学表述工具前后更加协调更加统一；在处理教材的理论体系上也有了相应的区别和提高．     

以培养能力为目标重新安排普物实验课──美国加州大学普物实验教改简介

美国伯克利加州大学物理系科学与数学教学组的 MARK ST JoHN对普通物理实验课的教改进行了一次大胆的试验;以培养学生的实验技能为目标,对普物实验课教材,教法和课程结构都作了重新安排,据说取得了一定的成绩,他先后于 1979年冬与 F.Reif联名在美国物理杂志①;1980年秋单独署名在美国物理教师杂志②发表专文作了报导.现将他进行的这次普物实验教改的主要精神和做法简介如下。以供当前从事普物实验教学的同志考虑教改时参考. M.S,JoHN这次实验是在医预科及生物系普物课中进行的,他认为学生通过普物实验课除应该学到知识和使用仪器的方…     

国防高科技与物理教学

本通过两个具体实例，阐明普物课程现代化的必要性和可能性以及基础物理教学如何与国防科技相联系的问题。     

光栅与全息照相

基于普物光学的双光束干涉和光栅衍射，定性分析全息照相。     

2010年栏目设置简要说明

1．科学前沿介绍物理学前沿问题的发展,来稿希望写得通俗易懂．2．物理学与科技创新（1）介绍历史上由物理学原理推动的科技创新（新技术的产生及应用）．（2）介绍最新物理学成就及其技术应用前景．3．课程改革探索当前大、中学课程改革有关的探索,包括理论的探讨及实践经验介绍,特别是作者亲自试验中的体会4．大学物理教学高校物理专业及非物理专业的普物、理物及相关课程的教学经验、体会．     

聚合物的结构转变和驻极体

一、引宫近年来国内高校普物实验的改进倾向于采用计算机代替手工调节和测量，但实验的物理内容仍局限于三十年代的范围．在经济条件许可下将新的技术和精密仪器引入普物实验教学有助于增长学生的见识；但实验教学更重要的目的在于启发学生运用自己的物理思想，以力所能及的方法去认识和研究新问题．50年代以后，高分子聚合物在日常生活、工业技术和尖端科学中得到越来越广泛的重要应用，但普物实验迄今未能增加这方面的内容，这是教学中的缺陷．聚合物由粘流态冷却经高弹态到达室温附近的类玻璃态，成为通常所称的塑料．其间经历的结构转变…     

普通物理实验教学改革的研究与实践

 1.普物实验课教学的现状实验教学是物理教学的重要组成部分,是培养学生实践能力和创新能力的有效途径,随着社会的发展及教育由应试教育向素质教育的转变,原有普物实验的教学体系和培养模式已远不能适应新时期社会对人才的需求,必须以现代教育教学的思想和理念为指导,进行深入细致的改革与实践。普物实验课教学存在的问题主要表现在以下几个方面:(1)普物实验不仅仅是一门实验性很强的实践课,它有其自身的理论体系、结构体系及其教学规律。有它自己的构成要素(实验思想、实验方法、实验仪器、实验设计、实验步骤、实验操作、数据分析与处理)。     

普物实验课件设计思想刍议

本阐述了设计思想是制作教学课件的前提和关键,并针对普物实验课程的特点,提出了普物实验课件设计中应注重的几个问题。     

用袖珍计算器改进振动周期的检测装置

普物实验是多数大专院校都开设的一门实验，面广而且有一定的实验个数．因此，仪器设备的购置和使用效率是一个很值得重视的问题．郑德佑同志的这篇文章介绍了用计算器测单摆周期的办法，从教学的角度看，单摆这个实验采用自动计数是否合适固然会有不同的看法和争议，但是利用计算器这种廉价商品，经过小改动后代替普物实验中一些价格昂贵且不见得可靠的仪器，这种做法无疑值得推广．     

A study on the best irradiation dose of X-ray for Hep-2 cells by Fourier transform infrared spectroscopy

Fourier transform infrared spectroscopy (FTIR) was employed to study the human epidermis larynx carcinoma cell lines (Hep-2) which were irradiated by different doses of X-ray.The results show that (1) the irradiation of X-ray damages the structure of the CH3 groups of the thymine in DNA,which restrains the reproduction of Hep-2 cells effectively,(2) the 8 Gy dose of X-ray irradiation changes the framework and the relative contents of some proteins,lipids and the nucleic acid molecules intercellular in the greatest degree,and (3) the 8 Gy dose of X-ray irradiation is the best irradiation dose for lowering the degree of the cancerization of Hep-2 cells according to the criteria for the degree of the cancerization reported recently.Meanwhile,the apoptosis of these cells were detected by using flow cytometry (FCM) primarily.It shows that the apoptotic ratio of the Hep-2 cells depends on the irradiation dose to some extent,but is not linearly.And the apoptotic ratio of the 12 Gy dose group is the maximum (20.36%),but the apoptotic ratios of the 2 to 8 Gy dose groups change little.     

Study on the radiation problem caused by electron beam loss in accelerator tubes

The beam dynamic code PARMELA was used to simulate the transportation process of accelerating electrons in S-band SW linacs with different energies of 2.5, 6 and 20 MeV. The results indicated that in the ideal condition, the percentage of electron beam loss was 50% in accelerator tubes. Also we calculated the spectrum, the location and angular distribution of the lost electrons. Calculation performed by Monte Carlo code MCNP demonstrated that the radiation distribution of lost electrons was nearly uniform along the tube axis, the angular distributions of the radiation dose rates of the three tubes were similar, and the highest leaking dose was at the angle of 160° with respect to the axis. The lower the energy of the accelerator, the higher the radiation relative leakage. For the 2.5 MeV accelerator, the maximum dose rate reached 5% of the main dose and the one on the head of the electron gun was 1%, both of which did not meet the eligible protection requirement for accelerators. We adopted different shielding designs for different accelerators. The simulated result showed that the shielded radiation leaking dose rates fulfilled the requirement.     

Analysis of Laser-generated Rayleigh wave on viscoelastic materials

In order to understand the viscoelasticity of material, this research has been conducted to study the propagation characteristics of viscoelastic Rayleigh wave theoretically. A model is presented for the pulsed laser generation of ultrasound on viscoelastic medium surface. Referred to the Kelvin model, the frequency equation and the normal displacement of viscoelastic Rayleigh wave were derived, the influence of the viscoelastic modulus on dispersion and attenuation was discussed. From the theoretical calculation, it is shown that the effect of viscoelasticity on the attenuation of Rayleigh wave is more than that on its dispersion. In the case of a weak viscosity, the attenuation of viscoelastic Rayleigh wave is directly proportional to viscosity modulus; the effect of shear viscosity on the attenuation is much more than that of bulk viscosity. The transient response of viscoelastic Rayleigh wave was also simulated using Laplace and Hankel inversion transform, which are showed in good agreement with the theoretic predictions. The model provides a useful tool for the determination of viscoelastic parameters of medium.     

Factors affecting the spectrum of an electromagnetic light wave on scattering from a semisoft boundary medium

The spectrum of an electromagnetic light wave on scattering from a semisoft boundary medium is discussed within the accuracy of the first-order Born approximation. It is shown that spectral shifts and spectral switches are affected both by the polarization of the incident light wave and by the characters of the scat-tering medium. Moreover, numerical results show that the direction at which the spectral switch occurs is governed by the characters of the scattering medium, whereas the magnitude of the spectral switch is affected by the polarization of the incident light wave.     

Tropical Monsoon Forest Thermodynamics Based on Remote Sensing Data

This paper addresses thermodynamic variables that characterize the energy balance and structure of the solar energy transformation by the ecosystems of deciduous tropical forests. By analyzing the seasonal dynamics of these variables, two main states of the thermodynamic system are determined: the end of the drought season and the end of the wet season. Two sub-systems of solar energy transformation are also defined: a balance system that is responsible for the moisture transportation between the ecosystem and atmosphere; and a structural bioproductional system responsible for biological productivity. Several types of thermodynamic systems are determined based on the ratio between the invariants of the variables. They match the main classes of the landscape cover. A seasonal change of thermodynamic variables for different types of thermodynamic systems is additionally studied. The study reveals that temperature above the forest ecosystems is about 4° lower than above the open areas during most of the year.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Time domain finite volume method for the transient response and natural characteristics of structural-acoustic coupling in an enclosed cavity

A time domain finite volume method（TDFVM）based on wave theory is developed to analyze the transient response and natural characteristics of structural-acoustic coupling problems in an enclosed cavity.In the present method,the elastic dynamic equations and acoustic equation in heterogeneous medium are solved in solid domains and fluid domains respectively.The structural-acoustic coupling is implemented according to the continuity condition of the particle velocity along the normal direction and the normal traction equilibrium condition on the interface.Several numerical examples are presented to validate the effectiveness and accuracy of the present TDFVM.Then the effects of water depth on the acoustic and vibration characteristics and the natural characteristics of a structural-acoustic coupling system are analyzed.The numerical results show that the increase of water depth leads to a stronger coupling between the water and structure and the decrease of natural frequencies of coupling system,The computational cost and memory of this method are small and it can be applicable to structural-acoustic coupling problems in the heterogeneous fluid.     

Temperature Sensitivity Control and Mechanical Stress Effect of Boron-Doped Long-Period Fiber Gratings

We will present in this work the quantitative analysis of the relationship between the doping concentrations of GeO 2 and B 2 O 3 in the core and cladding regions and the temperature sensitivity of the resonance wavelength shift in long-period fiber gratings (LPFGs). Based on this analysis, the temperature sensitivity was suppressed and enhanced to 0.002 nm/°C and 0.28 nm/°C, respectively. We will also discuss the effect of the residual mechanical stress on the optical and mechanical properties of LPFGs. In particular, we will present the measurement results of the dependence of the refractive index change and mechanical strength on the residual mechanical stress in the boron-doped fibers with depressed clad and matched clad.     

The effective absorption cross-section of thermal neutrons in a medium containing strongly or weakly absorbing centres

The structure of a heterogeneous system influences diffusion of thermal neutrons. The thermal-neutron absorption in grained media is considered in the paper. A simple theory is presented for a two-component medium treated as grains embedded in the matrix or as a system built of two types of grains (of strongly differing absorption cross-sections). A grain parameter is defined as the ratio of the effective macroscopic absorption cross-section of the heterogeneous medium to the absorption cross-section of the corresponding homogeneous medium (consisting of the same components in the same proportions). The grain parameter depends on the ratio of the absorption cross-sections and contributions of the components and on the size of grains. The theoretical approach has been verified in experiments on prepared dedicated models which have kept required geometrical and physical conditions (silver grains distributed regularly in Plexiglas). The effective absorption cross-sections have been measured and compared with the results of calculations. A very good agreement has been observed. In certain cases the differences between the absorption in the heterogeneous and homogeneous media are very significant. A validity of an extension of the theoretical model on natural, two-component, heterogeneous mixtures has been tested experimentally. Aqueous solutions of boric acid have been used as the strongly absorbing component. Fine- and coarse-grained pure silicon has been used as the second component with well-defined thermal-neutron parameters. Small and large grains of diabase have been used as the second natural component. The theoretical predictions have been confirmed in these experiments.     

影响单摆振动周期的参数研究

应用振动分析的方法,研究了单摆的周期受摆角、摆球的线度、地球纬度、摆球离地面的高度、介质黏度和介质密度参数的影响;作出了周期比随参数变化的曲线.结果表明:单摆的周期随摆角、摆球的线度、摆球离地面的高度、介质黏度和介质密度的增大而增大,随地球纬度的增大而减小.