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1.
判断水银柱移动方向可采用“压强变化法”,即先分析引起压强变化的原因,根据有关的定律,进而判断液柱的移动方向.由压强变化导致液柱移动的原因概括起来主要有:1)气体的温度变化;2)水银柱系统位置变化;3)系统作变速运动;4)添、减水银.  相似文献   

2.
从光的干涉原理出发,讨论了金属丝弹性模量的光电测量方法.设计了激光干涉法测量长度微变量的测量装置,并介绍了测量原理,给出了动镜移动方向判别电路.  相似文献   

3.
断续带状移动热源温度场的积分解   总被引:2,自引:0,他引:2  
在J.C.Jaeger和Des.Ruisseaux移动热源模型基础上,应用移动热源法及热源迭加原理求解出断续带状移动热源在半无限大物体上运动产生的三维非稳态温度场积分解通式。从而为分析诸如断续磨削等工程实际热问题提供了理论计算方法。  相似文献   

4.
胶原蛋白温度效应的Raman光谱研究   总被引:8,自引:2,他引:6  
在不同温度下对Ⅰ型胶原蛋白进行了拉曼光谱测定。结果表明:随温度的升高,多数谱线向低波数移动,但CH2的变形振动谱线1302cm^-1向高波数移动,苯丙氨酸的特征振动谱线1003cm^-1的波数基本保持不变。同时还给出了拉曼谱线强度随温度的变化关系,得到了0,40,68,90℃四个变性峰,其中40,68℃的峰与DSC(差示扫描量热法)和SHG(二次谐波法)的测量结果一致,0℃的峰为冰冻相变,90℃的变性峰为胶原的二级结构被破坏所致。当温度达到150℃时,谱线强度显著降低,大部分谱线消失,胶原的一级结构遭到破坏。实验还发现胶原纤维在低温区具有较好的复性特性。  相似文献   

5.
本文介绍一个调整双棱镜同轴等高的简易方法.该法采用先调节狭缝和目镜至基本等高,可使各光学部件快速调至同轴等高.通过随意移动棱镜和目镜在轨道上的位置,以便在实验中观察到清晰的干涉条纹;采用位移法测试,可从实验方法中加深理解光线直线传播和干涉现象的意义  相似文献   

6.
用B样条基组展开方法结合模型势计算了里德堡钠原子抗磁谱和相应的振子强度谱,径向和角向均采用高阶B样条基组.计算结果与已有的R-矩阵和多通道量子亏损理论相结合(R-matrix+MODT)法及其他理论计算结果作了比较,几种理论结果在我们所研究的能区内符合得非常好,本文方法较R-matrix+MQDT法简单,易于推广到交叉电磁场中里德堡原于的精确谱的计算中.  相似文献   

7.
应用分光计测量三棱镜折射率,最常用的方法就是熟知的最小偏向角法,还有掠人射法[1]与等顶角入射法[3].本文介绍临界法如下.按图示光路,由折射定律n棱镜折射率.i’全反射临界冷,为对应的偏向角.从几何关系可得若能求出r与、A的关系,就能测量、A计算出折射测量方法先按最小偏向法找到最小偏向角,将载物台继续朝原方向转动,边转动边观察狭缝像的移动及光强的变化,可以发现光强是愈来愈弱,狭缝像变得弥散,当望远镜的光轴与棱镜的AC面平行时,记录下左右游标读数,取下棱镜测入射光位置,可得偏向角,按常用方法测A。在一次测量…  相似文献   

8.
弹性力学的复变量无网格方法   总被引:12,自引:0,他引:12       下载免费PDF全文
程玉民  李九红 《物理学报》2005,54(10):4463-4471
在移动最小二乘法的基础上,提出了复变量移动最小二乘法.复变量移动最小二乘法的优点是采用一维基函数建立二维问题的逼近函数,所形成的无网格方法计算量小.然后,将复变量移动最小二乘法应用于弹性力学的无网格方法,提出了复变量无网格方法,推导了复变量无网格方法的公式.与传统的无网格方法相比,复变量无网格方法具有计算量小、精度高的优点.最后给出了数值算例. 关键词: 移动最小二乘法 复变量移动最小二乘法 无网格方法 弹性力学 复变量无网格方法  相似文献   

9.
鳀鱼(Engraulis japonicus)目标强度的模型法研究   总被引:5,自引:0,他引:5       下载免费PDF全文
于海圆  赵宪勇 《应用声学》2007,26(5):267-276
采用声散射理论和目标强度近似模型评估法对黄海鲤鱼(Engraulis japonicus)的声散射特征和目标强度进行了数值计算与评估研究。散射模型由鱼鳔模型和鱼体模型两个部分构成,其中鱼鳔采用充满气体的椭球体模型,鳔除外的鱼体采用充满液体的椭球体模型。理论数值计算所需参数取自全长12.6cm的鲤鱼个体,其鱼鳔尺寸利用X光照片测得。平均目标强度利用模型算得的不同角度下的声散射强度与鲲鱼倾角分布函数的卷积计算,其中倾角(度)的分布函数设为N(-3.9,12.8^2)。结果显示,鲲鱼对声波的散射具有明显指向性;在38kHz和120kHz工作频率下,鲲鱼的最大背向目标强度分别为-41.2dB和-39.5dB,有效平均目标强度分别为-48.0dB和-51.5dB,与实测结果吻合较好。另外还对鲲鱼的反向散射指向性特征、目标强度的频率特征以及鱼鳔对鲲鱼整体目标强度的贡献等进行了分析与讨论。以上研究表明,模型法作为现场测定研究方法的重要补充和认知鱼类声学散射特性的有效途径,可在我国鱼类目标强度的研究中发挥重要作用。  相似文献   

10.
硫化铋微晶掺杂薄膜的制备及光学性能的研究   总被引:1,自引:0,他引:1  
叶辉  何迪洁 《光学学报》1994,14(5):18-522
用溶胶-凝胶法能够有效地制备含0.5%的具有量子尺寸效应的Bi2S3微晶掺杂硅薄膜。薄膜的室温透射光谱发现,在500℃热处理时,随着热处理时间的延长,薄膜的特征透射谱谷会发生向长波方向的移动,作者认为这样的移动于量子尺寸效应。本文还报道了在YAG强激光的作用下能够观察到薄膜样品所产生的倍频信号,并讨论了产生倍频的原因。  相似文献   

11.
A large family of cosh-Gaussian travelling wave solution of a complex Ginzburg–Landau equation (CGLE), that describes dissipative semiconductor laser cavity is derived. Using perturbation method, the stability region is identified. Bifurcation analysis is done by smoothly varying the cavity loss coefficient to provide insight of the system dynamics. He’s variational method is adopted to obtain the standard sech-type and the not-so-explored but promising cosh-Gaussian type, travelling wave solutions. For a given set of system parameters, only one sech solution is obtained, whereas several distinct solution points are derived for cosh-Gaussian case. These solutions yield a wide variety of travelling wave profiles, namely Gaussian, near-sech, flat-top and a cosh-Gaussian with variable central dip. A split-step Fourier method and pseudospectral method have been used for direct numerical solution of the CGLE and travelling wave profiles identical to the analytical profiles have been obtained. We also identified the parametric zone that promises an extremely large family of cosh-Gaussian travelling wave solutions with tunable shape. This suggests that the cosh-Gaussian profile is quite generic and would be helpful for further theoretical as well as experimental investigation on pattern formation, pulse dynamics and localization in semiconductor laser cavity.  相似文献   

12.
A direct algebraic method is introduced for constructing exact travelling wave solutions of nonlinear partial differential equations with complex phases. The scheme is implemented for obtaining multiple soliton solutions of the generalized Zakharov equations, and then new exact travelling wave solutions with complex phases are obtained. In addition, by using new exact solutions of an auxiliary ordinary differential equation, new exact travelling wave solutions for the generalized Zakharov equations are obtained.  相似文献   

13.
《Physics letters. A》1988,128(9):483-487
A method of constructing travelling wave solutions for nonlinear diffusion equations with polynomial nonlinearities is demonstrated. By certain assumptions some bounded travelling wave solutions are found. One of the results is the first known exact solution for the Fisher equation.  相似文献   

14.
This paper is concerned with the existence and the stability of travelling waves for a class of quasilinear cross-diffusion systems describing two competing or predator-prey species. Firstly, by geometric singular perturbation method, the existence of travelling waves with transition layers is proved, which extends the results of Hosono and Mimura [Y. Hosono, M. Mimura, Singular perturbation approach to travelling waves in competing and diffusion species models, J. Math. Kyoto Univ. 22 (1982) 435–461] and Gardner [R.A. Gardner, Topological Methods Arising in the Study of Travelling Waves, Reaction–Diffusion Equations, Clarendon Press, Oxford, 1990, pp. 173–198] for non-cross-diffusion systems and Wu [Y. Wu, The existence of travelling waves for a cross-diffusion system with small parameter, Beijing Math. 3 (1997) 74–85] to more general cross-diffusion systems. Applying the stability index method introduced in Alexsander et al. [J. Alexsander, R.A. Gardner, C.K.R.T. Jones, A topological invariant arising in the stability analysis of travelling waves, J. Die Reine Angewandte Math. 410 (1990) 167–212] and Gardner and Jones [R.A. Gardner, C.R.K.T. Jones, Stability of travelling wave solutions of diffusive predator–prey systems, Trans. Am. Soc. 327 (1991) 465–524] to the more general eigenvalue problem induced by the quasilinear cross-diffusion systems, by detailed spectral and topological analysis, the travelling waves with transition layers for the cross-diffusion systems are proved to be stable, which also extends the results of Gardner and Jones [R.A. Gardner, C.R.K.T. Jones, Stability of travelling wave solutions of diffusive predator–prey systems, Trans. Am. Soc. 327 (1991) 465–524] to the more general systems.  相似文献   

15.
In this paper, travelling wave solutions for the generalized time-delayed Burgers-Fisher equation are studied. By using the first-integral method, which is based on the ring theory of commutative algebra, we obtain a class of travelling solitary wavesolutions for the generalized time-delayed Burgers-Fisher equation.A minor error in the previous article is clarified.  相似文献   

16.
欧阳成  石兰芳  林万涛  莫嘉琪 《物理学报》2013,62(17):170201-170201
研究了一类(2+1)维扰动时滞破裂孤波方程. 首先讨论了对应的无时滞情形下的破裂方程,利用待定系数投射方法得到了孤波精确解. 再利用同伦、摄动近似方法得到了扰动破裂孤波方程的行波渐近解. 关键词: 孤波 行波解 近似解  相似文献   

17.
A unified approach is presented for finding the travelling wave solutions to one kind of nonlinear evolution equation by introducing a concept of "rank". The key idea of this method is to make use of the arbitrariness of the manifold in Painleve analysis. We selected a new expansion variable and thus obtained a rich variety of travelling wave solutions to nonlinear evolution equation, which covered solitary wave solutions, periodic wave solutions, Weierstrass elliptic function solutions, and rational solutions. Three illustrative equations are investigated by this means, and abundant travelling wave solutions are obtained in a systematic way. In addition, some new solutions are firstly reported here.  相似文献   

18.
《Physics letters. A》1997,229(4):217-220
Explicit travelling solitary wave solutions to a compound KdV-Burgers equation are obtained by using an automated method. A two-dimensional generalization is discussed.  相似文献   

19.
《Physics letters. A》2006,356(2):124-130
A new auxiliary ordinary differential equation and its solutions are used for constructing exact travelling wave solutions of nonlinear partial differential equations in a unified way. The main idea of this method is to take full advantage of the auxiliary equation which has more new exact solutions. More new exact travelling wave solutions are obtained for the quadratic nonlinear Klein–Gordon equation, the combined KdV and mKdV equation, the sine-Gordon equation and the Whitham–Broer–Kaup equations.  相似文献   

20.
By using the method of dynamical system, the bidirectional wave equations are considered. Based on this method, all kinds of phase portraits of the reduced travelling wave system in the parametric space are given. All possible bounded travelling wave solutions such as dark soliton solutions, bright soliton solutions and periodic travelling wave solutions are obtained. With the aid of Maple software, numerical simulations are conducted for dark soliton solutions, bright soliton solutions and periodic travelling wave solutions to the bidirectional wave equations. The results presented in this paper improve the related previous studies.  相似文献   

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