理斟考试中的亮点之一-信息题

理科综合考试说明中明确要求考生能读懂自然科学方面的资料，因此在高考中经常出现要求考生从文字或图表中提取一些信息，从中采集一些要点，然后运用已学的有关知识进行处理．因此，同学们在平时要给予必要的关注和重视．下面就结合实际例题谈谈信息题的解题方法．     

高灰度分辨率图像的伪彩色编码

提出了一种基于RGB三基色系统的对高灰度分辨率图像进行伪彩色编码的非线性方法。在该方法中 ,对小于 2 4位灰度分辨率的图像来说 ,任一空间 (x ,y)处的灰度值 f(x ,y)均可用 2 4位二进制数 fi(i=0 ,1,… ,2 3)来表示。通过Ri=f3i,Gi=f3i+1,Bi=f3i+2 (i =0 ,1,… ,7)进行非线性编码 ,得到 3个 8位二进制数R ,G和B ,将其分别乘以KR,KG和KB 规模因子后 ,作为RGB三基色系统的三色系数 ,实现了灰度图像的等密度伪彩色编码。该方法通用性强 ,可实现 1位到 2 4位灰度图像的伪彩色编码 ,并且处理高分辨率灰度图像与处理低分辨率灰度图像的方法是一致的 ,速度也是相同的     

计算刚体转动惯量的一个新定理

本文介绍了计算刚体转动惯量的一个新定理，给出了它的一个推论．通过此定理对四个例题的应用，说明它具有简单、快捷的优点并有独到之处．     

一种用于选择性分割的动态轮廓模型

Chan和Vese提出了一种水平集方法解动态轮廓曲线方程用于图像分割，该方法不需要由图像梯度分布所给出的边界。该算法基于Mumford—Shah能量最小方程而发展的，有两个主要的局限性，一是只能处理在直方图中为双峰的图像，即只能将图像分割为两种区域，二是该方法在解非线性偏微分方程中采取平均曲率演化方法时特别耗时。     

孰先孰后判定的6种方法

孰先孰后即比较物体运动时间长短的问题，是高中物理中常见的问题．由于这类问题的物理情景往往比较新颖，涉及的知识跨度较大，同学们解答起来颇感棘手．本文拟结合典型例题的解析，说明比较时间的6种方法．     

浅析“摩擦生热”关系式的应用

涉及摩擦力的各类问题是同学们学习的难点．下面就摩擦力做功的特点及能量转化的关系作归类分析，并通过典型例题说明．     

镧系超导体1／8反常现象的研究

我们测量了La2-xMxCuO4（LMCO，M=Sr，Ba，x=0．05，0．10，0．125，0．15，0．2）体系的室温正电子寿命谱，研究了正电子湮没机制与超导电性之间的关系．实验结果表明在x=1／8附近电子密度（ne）出现峰值响应，说明在掺杂浓度不断增加的过程中，当x〈1／8时，正电子-空穴反关联起决定性的作用．而在x〉1／8时，化学掺杂引起的电子损失是决定电子密度的最重要的原因．     

MATLAB在大学物理实验中的应用

MATLAB是一种集数值计算和图形处理等功能于一体的工程计算应用软件．由于它的语言经过简单学习便能掌握和使用,在欧美各高等院校,MATLAB已成为本科生、硕士生、博士生必须掌握的基本软件．作为工科院校,我们在一年级学生开设的大学物理实验课程中就尝试引人MATLAB,要求学生初步学会MAT—LAB语言,能编写简单的程序对物理实验数据进行处理,并运用最小二乘法画出准确的拟合曲线．     

浅谈物理教学中"收集、整理信息的能力"的培养——一道例题引发的思考

在复习“恒定电流”一章时,笔者原本认为较简单的一道例题,可学生解题的正确率几乎为零．这让我很惊讶．例题如下．例题：图1所示为一个电灯两端的电压与通过它的电流的变化关系曲线,可见两者不成线性关系,     

电场强度的微分

一、电场强度微分的物理意义 从数学上我们知道: 函数f(x,y)的偏微分为: 现在我们来说明函数微分的物理意义。注意到(1)式的微分是对标量函数而进行的,所以对向量场必须进行向量分解。例如电场强度E,在直角坐标系就必须分解成平行x轴的Ex和垂道x轴的Ey。然后分别微分。我们以点电荷的电场强度为例进行说明。 设一正点电荷+q位于直角坐标系的原点0,它在场点(x,y)所产生的电场强度的两个分量为Ex、Ey。Ey在y=常数的直线上的变化曲线如图1中的曲线①所示。根据(1)式有:由上式可知:△x为Ey曲线上相距△x的两场值之差。如图1中的曲线③所示。…     

Energy losses of a charged particle in a plasma in the presence of a strong electric field as a function of the sign of the charge

Institute of Radiophysics and Electronics, Academy of Sciences of the Armenian SSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 4, pp. 347–351, April, 1991.     

On the dynamics of a particle on a cone

A detailed study of the classical and quantum mechanics of a free particle on a double cone and a particle bound to its tip by a harmonic oscillator potential is presented.     

On the dynamics of a particle on a hyperboloid

A free particle moving on a one-sheeted hyperboloid is discussed both at the classical and quantum levels.     

On the asymmetry of a random walk in the presence of a field

Any ensemble of random walks with symmetric transition probabilities will have symmetric properties. However, any single realization of such a random walk may be asymmetric. In an earlier paper, Weiss and Weissman developed a measure of asymmetry and applied it to random walks in the absence of a field, showing that the degree of asymmetry (in the diffusion limit) is independent of time and that the most probable degree of asymmetry corresponds to the maximum possible. We show in the present paper how the presence of a symmetric field can change this result, both in making the degree of asymmetry depend on time, and driving the random walk toward a more symmetric state.     

Effect of the field of a nonlinear electromagnetic wave on the shape of a soliton in a semiconductor superlattice

The effect of the electric component of the field of a high-frequency (HF) nonlinear electromagnetic (EM) wave on the propagation of a solitary EM wave (soliton) in a quantum semiconductor superlattice is studied. It is noted that in the collisionless approximation, the solution of the modified sine-Gordon equation corresponding to the amplification of an EM pulse that, with allowance made for interminiband electron transitions, transforms into a dissipative soliton is possible. The effect of electron collisions with irregularities of the crystal lattice on the soliton dynamics under the action of the field of a HF nonlinear wave is considered. The condition for an increase in the traveling time of the solitary wave is found.     

Influence of the polarity of a medium on the photonics of a merocyanine dye with a high quadratic polarizability

The influence of the polarity of a medium on the spectral and luminescent properties of 2-[(2E,4E)-6-(1,3,3-trimethyl-2,3-dihydro-1H-2-indolyliden)-2,4-hexadienyliden]malononitrile (THDM) in solutions and polymer matrices is studied at room temperature under conditions of steady-state and pulsed laser excitation. A large bathochromic shift of the absorption spectra observed upon an increase in the polarity of a solvent is caused by a strong increase in the molecular dipole moment μ due to a transition of molecules from the ground state (μ_g = 7.6 D) to an excited Franck-Condon state (μ^FC = 33.5 D). Based on the solvatochromic data, the quadratic polarizability was calculated to be β = (3.2 ± 0.6) × 10^?28 esu, which is close to the experimentally determined value β_ex = (3.9 ± 0.2) × 10^?28 esu. A strong narrowing of the fluorescence spectra in comparison with the absorption spectra is observed upon an increase in the solvent polarity. This narrowing is explained by a decrease in the bond length alternation parameter and by weakening of vibronic interactions in the singlet excited state. The dynamic solvatofluorochromism of THDM in the picosecond range is caused by reorientations of molecules of the polar environment occurring during a time period consistent with the dielectric relaxation time of these molecules.