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1.
黄萧  于鑫 《力学学报》2017,49(5):1145-1153
相比气体,固体介质在高压下的状态方程更为复杂,形式也多种多样.现有关于固体介质中激波反射的理论研究,一般直接采用某种状态方程,缺乏对采用不同状态方程得到的结果的对比.本项工作采用激波极曲线的理论分析方法,选择4种不同组合形式的状态方程(一次冲击激波采用线性的冲击波速度与粒子速度关系式,二次冲击激波采用Gr(u|¨)neisen状态方程;一次冲击和二次冲击激波均采用冲击波速度与粒子速度关系式:一次冲击激波采用线性冲击波速度与粒子速度关系式,二次冲击激波采用刚性气体状态方程;以及一次冲击激波和二次冲击激波均采用刚性气体状态方程),研究固体介质中的斜激波反射,比较了采用不同组合形式的状态方程对反射激波波后压力的影响.利用量纲分析方法讨论了简化状态方程达到较高精度的条件.此外,用ANSYS/LS-DYNA软件,对激波极曲线理论给出的结果进行了验证.本项工作可为固体介质中激波反射问题状态方程的选取提供一定的指导.  相似文献   
2.
于鑫 《物理》2003,32(9):595
这是一本由一位令人敬重的中国学者撰写的光学性质方面的经典著作 .其第一版是 1992年问世的 ,有里程碑标志意义 ,是第一本有关半导体光学性质的论著 .其写作定位的读者群是相关科学和技术领域内的研究生和科研工作者 .当时论著已涉猎了多方面的丰富内容 ,但其中仅有一章讨论量子阱光学性质 (该领域的最新研究成就 ,译者注补 ) .书的印刷质量按西方的标准看来是相当差的 ,书的后面缺少主题索引 .在第二版中作者对第一版的论述内容作了极其重要的 (significantly)拓展 .新增加了一章 ,并在其他各章中新添加了若干小节 .例如 ,在第一章中增添…  相似文献   
3.
Burgers-type equations can describe some phenomena in fluids,plasmas,gas dynamics,traffic,etc.In this paper,an integrable hierarchy covering the lattice Burgers equation is derived from a discrete spectral problem.N-fold Darboux transformation(DT) and conservation laws for the lattice Burgers equation are constructed based on its Lax pair.N-soliton solutions in the form of Vandermonde-like determinant are derived via the resulting DT with symbolic computation,structures of which are shown graphically.Coexistence of the elastic-inelastic interaction among the three solitons is firstly reported for the lattice Burgers equation,even if the similar phenomenon for certern continuous systems is known.Results in this paper might be helpful for understanding some ecological problems describing the evolution of competing species and the propagation of nonlinear waves in fluids.  相似文献   
4.
The aerodynamic forces and flow structures of two airfoils performing “fling and subsequent translation“ and “translation and subsequent clap“ are studied by numerically solving the Navier-Stokes equations in moving overset grids. These motions are relevant to the flight of very small insects. The Reynolds number, based on the airfoil chord length c and the translation velocity U, is 17. It is shown that: (1) For two airfoils performing fling and subsequent translation, a large lift is generated both in the fling phase and in the early part of the translation phase. During the fling phase,a pair of leading edge vortices of large strength is generated; the generation of the vortex pair in a short period results in a large time rate of change of fluid impulse, which explains the large lift in this period. During the early part of the translation, the two leading edge vortices move with the airfoils;the relative movement of the vortices also results in a large time rate of change of fluid impulse, which explains the large lift in this part of motion. (In the later part of the translation, the vorticity in the vortices is diffused and convected into the wake.) The time averaged lift coefficient is approximately 2.4 times as large as that of a single airfoil performing a similar motion. (2) For two airfoils performing translation and subsequent clap, a large lift is generated in the clap phase. During the clap, a pair of trailing edge vortices of large strength are generated; again, the generation of the vortex pair in a short period (which results in a large time rate of change of fluid impulse) is responsible for the large lift in this period. The time averaged lift coefficient is approximately 1.6 times as large as that of a single airfoil performing a similar motion. (3) When the initial distance between the airfoils (in the case of clap, the final distance between the airfoils) varies from 0.1 to 0.2c, the lift on an airfoil decreases only slightly but the torque decreases greatly. When the distance is about lc, the interference effects between the two airfoils become very small.  相似文献   
5.
对干涉式光纤传感器来说,光源的谱宽直接影响着传感器的工作特性。从法布里—珀罗干涉式光纤传感器出发,推导其灵敏度的理论表达式,并用MathCAD软件进行了数学分析。讨论了光源谱宽对传感器灵敏度的影响。介绍了具有温度反馈功能的法布里—珀罗光纤干涉实验系统,给出了用该实验系统拍摄的谐振曲线照片。从该系统进行的两个重要的实验(不同干涉腔长的灵敏度对比实验和不同干涉长度的光源实验)表明,法布里—珀罗干涉式光纤传感器的灵敏度与光源谱宽的理论表达式是正确的,理沦公式与实验结论能很好地吻合。最后指出了该方法可以用于分析其他类型的干涉式光纤传感器的灵敏度问题,为光源的选择提供了参考。  相似文献   
6.
<正>束星北(1907~1983)早期在相对论、量子力学、无线电和电磁学等方面均有涉猎,对相对论和无线电造诣颇深,抗战时期曾参与研制我国最早的雷达。他还是我国著名的气象科学家和海洋物理学家,为开创我国海洋物理研究做出了贡献。束星北半生辉煌,半生坎坷,即使在1955年至1978年长达23年期间,政治上受到不公正待遇,被剥夺了科研的条件和时间的情况下,仍然为培养人才不懈努力。拨乱反正以后,  相似文献   
7.
Han-Bin Deng 《中国物理 B》2021,30(12):126801-126801
Interface can be a fertile ground for exotic quantum states, including topological superconductivity, Majorana mode, fractal quantum Hall effect, unconventional superconductivity, Mott insulator, etc. Here we grow single-unit-cell (1UC) FeTe film on NbSe2 single crystal by molecular beam epitaxy (MBE) and investigate the film in-situ with a home-made cryogenic scanning tunneling microscopy (STM) and non-contact atomic force microscopy (AFM) combined system. We find different stripe-like superlattice modulations on grown FeTe film with different misorientation angles with respect to NbSe2 substrate. We show that these stripe-like superlattice modulations can be understood as moiré pattern forming between FeTe film and NbSe2 substrate. Our results indicate that the interface between FeTe and NbSe2 is atomically sharp. By STM-AFM combined measurement, we suggest that the moiré superlattice modulations have an electronic origin when the misorientation angle is relatively small (≤ 3°) and have structural relaxation when the misorientation angle is relatively large (≥ 10°).  相似文献   
8.
为了对一种TATB基非均质炸药的预冲击起爆现象展开数值模拟研究,将基于冲击温度及压力的AWSD反应率模型耦合进二维结构网格拉氏弹塑性流体力学程序。利用炸药及其产物的冲击雨贡纽实验数据校验了未反应炸药及产物的状态方程参数,通过一维冲击起爆的模拟,标定了反应速率模型参数。模拟了炸药在弱冲击0.45 μs后跟随的强冲击波的二次冲击实验,结果表明,受预压缩区域的炸药反应变慢,到爆轰距离增长了约1 mm,与该炸药二次冲击实验减敏现象相符。模拟拐角效应时,爆轰波经过拐角后,在拐角附近形成稳定的不起爆区域,与主要成分相同的LX-17炸药的拐角效应实验的死区特征相符。数值模拟结果表明,基于冲击温度及压力的AWSD反应率模型可以较好地模拟非均质炸药预冲击减敏问题。  相似文献   
9.
采用双通道差分式红外气体检测方法,基于比尔朗伯理论做针对性修正,研制出低检测下限、高探测性能的手持式红外甲烷气体检测仪.通过TracePro光线模拟软件,对比分析多种光学路径结构,得到小空间内长光程气室结构,增强气体有效吸收,提高仪器检测性能.引入多参数补偿算法,对气体吸收理论进行优化,得到适应本检测系统的气体吸收函数,以保证气体浓度信息计算准确性.仪器工作时最大输出电流为130mA,采用干电池供电,仪器的尺寸为209mm×70mm×40mm,甲烷气体浓度爆炸限以下最低检测限可达到50ppm,可以保证气体防爆的安全性要求.  相似文献   
10.
性质上的多样性使得对碳材料的研究一直以来都是热门课题.随着纳米技术的不断发展,尤其是扫描探针显微镜(SPM)的应用,促使表面化学成为当今热门的研究领域之一.近年来,包括本课题组在内的国内外很多研究组利用扫描探针显微镜,在超高真空(UHV)条件下通过在表面活化碳氢、碳卤键,构筑了多种新颖碳纳米结构.本文结合本课题组的近期研究工作,着重介绍了在金属表面通过碳氢、碳卤活化的手段构筑碳纳米结构的研究,并对前体分子在表面的反应性进行了探究.  相似文献   
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