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1.
肖伯钧 《大学物理》2003,22(5):22-24
讨论了银道面内的引力场强分布和太阳在银河系中所受引力与到银心距离r的关系,指出引力场强g并不是与r的平方成反比,这是由于银河系的大小和形状不能忽略造成的.强调了万有引力定律的适用条件.  相似文献   

2.
There is a tunnel connecting the beamcorridor and the target station in the spectrum hall in the CSNS project.The length of the tunnel is about 20 m.The shielding design of the tunnel is very significant for the persons working in the spectrum hall because the tunnel is not covered ed soil for shielding.In order to reduce the dose rate at the exit of the cable ducts,we use the ISIS construction,which is designed with four turnings,as a reference for the tunnel design.The thickness of the shielding is obtained by a simulationwith the Monte Carlo Code FLUKA.The result is compared with the data obtained with Moyer Mode and the reliability of the simulation is proved.This paper provides the basis for the design of the tunnel.  相似文献   

3.
There is a tunnel connecting the beamcorridor and the target station in the spectrum hall in the CSNS project. The length of the tunnel is about 20 m. The shielding design of the tunnel is very significant for the persons working in the spectrum hall because the tunnel is not covered by soil for shielding. In order to reduce the dose rate at the exit of the cable ducts, we use the ISIS construction, which is designed with four turnings, as a reference for the tunnel design. The thickness of the shielding is obtained by a simulation with the Monte Carlo Code FLUKA. The result is compared with the data obtained with Moyer Mode and the reliability of the simulation is proved. This paper provides the basis for the design of the tunnel.  相似文献   

4.
宿玉勇 《物理实验》2005,25(2):33-34
通过对欧姆表原理的分析,发现它相当于一个内电阻可变的电源,结合二极管的伏安特性曲线,可解释用欧姆表的不同量程测同一二极管得到的电阻值不同的问题.  相似文献   

5.
杨航  余玉民  张云飞  黄文  何建国 《强激光与粒子束》2021,33(10):101003-1-101003-8
磁流变抛光在其实际工作过程中,抛光区域几何特征的不同将会对流场创成的关键参数产生很大的影响。针对此问题建立三维模型与实验仿真展开研究。在研究抛光区域几何特征与流场创成关键参数的关系时,先改变抛光区域形状,观察其对流场创成中剪切应力、压力产生的影响;再控制抛光区域的形状相同时,通过改变抛光区域尺寸大小,观察对流场创成中剪切应力、压力产生的影响。结果表明:当抛光区域形状不同时,抛光区域为凹面时剪切应力最大,抛光区域为凸面时剪切应力最小。当抛光区域形状为凸面时,抛光区域两边的剪切应力随着抛光区域曲率大小增大而增大;当抛光区域形状为凹面,抛光区域两边的剪切应力随着抛光区域曲率大小增大而减小。当抛光区域形状不同时,抛光区域为凹面时压力最大,抛光区域为凸面时压力最小。当抛光区域形状为凸面时,抛光区域处的压力随着抛光区域曲率增大而增大;当抛光区域形状为凹面时,抛光区域处的压力随着抛光区域曲率增大而减小。  相似文献   

6.
关于工件振动对激光扫描在线检测精度影响的研究   总被引:2,自引:0,他引:2  
乔宏 《光学技术》2000,26(2):150-152
根据激光扫描在线检测的特点 ,在理论上对JSY 1型激光扫描尺寸自动检测仪的平均扫描速度和扫描角进行了分析和计算。通过一些实例 ,探讨了工件振动与扫描检测之间的关系。结果表明 :工件振动对激光扫描检测精度的影响很小 ,调整激光扫描完全适用于工件的非接触在线尺寸检测  相似文献   

7.
基于大气运动是一种不可逆过程的观点,引进了忆及过去时次资料的记忆函数,导出热传导的自忆性方程,研究了方程分别取Richardson和DuFort-Frankel格式,回溯阶p取1时的稳定性.探讨了多时刻模式中数值积分有时发散的问题,揭示了由过去时次资料动态求取记忆函数,改变了原定设计的差分格式,且它是一个时间平滑因子的本质. 关键词: 回溯阶差分格式 多时次 稳定性 记忆性  相似文献   

8.
G P Malik  L K Pande 《Pramana》1987,29(4):351-357
By reexamining the analysis of Basu and Biswas, based on the stereographic projection method of Fock and Levy, it is shown that the general solution of the Wick-Cutkosky model in the instantaneous approximation, hitherto unreported, involves only one quantum number; this is contrasted with the well-known solution which involves two quantum numbers, but for which the spectrum is degenerate with respect to one of them. The latter situation is shown to hold under a rather special circumstance.  相似文献   

9.
弹丸对钢筋混凝土中钢筋交汇处侵彻效应研究   总被引:2,自引:0,他引:2       下载免费PDF全文
考虑弹丸在钢筋交汇处与钢筋直接发生作用的情况,提出了弹丸侵彻钢筋混凝土的近似模型。利用该模型得到了弹丸侵彻钢筋混凝土过程中弹丸的加速度时间历程。计算结果与实验结果符合较好。用该模型分析了不同配筋结构、配筋尺寸和网眼尺寸对侵彻深度和侵彻过程的影响,结果表明:弹丸从钢筋交汇处侵彻时,当弹丸动能相对较小时,随着网眼尺寸的减小,弹丸的大部分能量均消耗在侵彻第一层配筋结构中,当弹丸动能较大时,不管网眼尺寸多大,第一层配筋均只消耗掉弹丸的部分能量;配筋直径和网眼尺寸对侵彻深度的影响较大。  相似文献   

10.
建立相关的力学模型,讨论运动员在单杠旋转运动中如何增加旋转能量,杠的刚柔性对旋转运动的影响和伸展、收缩的最佳时机选择等若干问题.充分展示了力学模型对研究问题的重要意义和作用.  相似文献   

11.
陆艺  范伟军孔明 《光子学报》2014,39(6):1111-1115
采用激光干涉检测的方法,综合应用计算机控制、数字图像处理等技术对高精密仪器主动镜的偏转角进行了检测.设计了主动镜的光干涉CCD数字图像检测系统,推导出了干涉条纹与主动镜偏转角之间的对应数学关系式,对条纹图像进行了噪音分析和相应的预处理,在干涉条纹细化的基础上对每条干涉条纹采用最小二乘法进行直线拟合,得到条纹间的间距以及条纹的方向角,最终检测出主动镜X轴方向的偏转分辨率为0″.113,最大偏转角为56″.872,Y轴方向的偏转分辨率为0″.112,最大偏转角为49″.835,完成了主动镜偏转角的检测.  相似文献   

12.
The disagreement between the experimental and calculated positions of the first convergence zone are known from many publications. The most probable cause for such a disagreement, namely, the incorrect specification of the input data for the calculations, is considered. The lack of simultaneity between the hydrological surveys of the region and the acoustic experiments is emphasized. The experimental data obtained by the author in five ocean regions are presented. These data characterize the diurnal variability of the distance from the source to the nearest boundary of the convergence zone. The relations proposed by different researchers for calculating the sound speed from the temperature, salinity, and hydrostatic pressure are analyzed. It is shown that these relations lead to a substantial difference in the estimated depth dependence of the hydrostatic gradient of the sound speed. The position of the first convergence zone is calculated for the propagation conditions determined by vertical temperature and salinity profiles with the subsequent recalculation of these profiles into sound speed profiles by using eight different formulas known from the literature. It is shown that different formulas lead to different values of the distance to the first zone; this difference is substantially greater than that between the calculations and experiment. The necessity of improving the recalculation relations in view of the experimental data on sound propagation in natural oceanic waveguides, including the data on the actual positions of the convergence zones, is emphasized.  相似文献   

13.
A comprehensive analysis of the application of the method of collective coordinates to the two dimensional Higgs model is given. First the instanton solution is derived, and the geometry of configuration space, and the construction of Schrodinger wave functionals are discussed. It is then explicitly verified that the Goldstone mode is the projection of the vacuum state onto the generator of the broken symmetry. The elimination of this Goldstone mode by means of the unitary gauge condition is demonstrated to the the crucial point in the construction of a consistent perturbation procedure. The parameter of the broken symmetry group is then used as the collective coordinate for field configurations around a minimum of the interaction. Throughout, the discussion is sufficiently detailed in order to facilitate the application of the method to other fields.  相似文献   

14.
薛海中  雷鸣  张海涛  李伟  过振  巩马理 《光学技术》2007,33(2):223-225,229
研究激光对远距离运动目标的辐照功率在激光通信、激光破坏等领域具有重要意义。一般估算辐照功率时常忽略目标的随机运动。在考虑目标的随机运动概率密度分布的基础上,建立了远距离运动目标的精确激光辐照功率模型,并与辐照静止目标时的情形进行了定量的分析比较。辐照运动目标等效于扩大的激光束辐照静止目标。当系统的瞄准方差小于由模型计算出的等效静止方差极限时,可将目标看作为静止状态,由此带来的辐照功率估算误差小于10%,否则在计算时必须考虑目标的运动状态。  相似文献   

15.
《Comptes Rendus Physique》2014,15(4):300-308
The shape and composition of the primary spectrum as well as the large-scale anisotropy in the arrival direction of cosmic rays are key elements to understand the origin, acceleration and propagation of the Galactic radiation. Besides the well-known knee and ankle features, the measured energy spectrum exhibits also a less pronounced but still clear deviation from a single power law between the knee and the ankle, with a spectral hardening at 2×1016eV and a steepening at 1017eV. The average mass composition gets heavier after the knee till 1017eV, where a bending of the heavy component is observed. An indication of a hardening of the light component just above 1017eV has been measured as well. First indications of anisotropy of the arrival direction in the southern hemisphere have been reported at 1015eV.  相似文献   

16.
探索了 X射线照片密度与显微密度计信号电压之间的关系。利用曲线拟合得到了 X射线照片光密度与输出电压关系的公式。经公式计算的密度值与实测密度值之间差别不大 ,其标准估计误差为 0 .0 178,完全可以用计算密度值来代替实测密度值。直接取其显微密度计输出的电信号 ,经公式转换成光学密度值后再进行 X射线照片的各种性能测试 ,避免了部分测试和换算误差 ,克服了过去密度测量的不便 ,提高了效率  相似文献   

17.
The gravitational Szekeres differential system is completely integrable with two rational first integrals and an additional analytical first integral. We describe the dynamics of the Szekeres system when one of these two rational first integrals is negative, showing that all the orbits come from the infinity of R4 and go to infinity.  相似文献   

18.
讨论了在放置与不放置焦斑形态控制器件KPP的两种情况下,采用功率谱密度模拟分析有旁瓣焦斑的激光束波前分布的特点,并由此探讨高功率激光驱动器在无旁瓣的聚焦情形下,对入射到打靶透镜的激光束波前畸变量的控制要求。  相似文献   

19.
产生旁瓣的激光波前功率谱密度与焦斑性能分析   总被引:3,自引:2,他引:1  
讨论了在放置与不放置焦斑形态控制器件 KPP的两种情况下 ,采用功率谱密度模拟分析有旁瓣焦斑的激光束波前分布的特点 ,并由此探讨高功率激光驱动器在无旁瓣的聚焦情形下 ,对入射到打靶透镜的激光束波前畸变量的控制要求。  相似文献   

20.
An asymptotic equivalence theorem is proven between the solutions of the initial value problem in all space for the Boltzmann and Enskog equations for initial data which assure global existence for the solutions to the initial value problem for one of the two equations. The proof is given starting from the solution of the Boltzmann equation, then the proof line is simply indicated when one starts from the Enskog equation. The proof holds for Knudsen numbers of the order of unity and equivalence is proven when the scale of the dimensions of the gas particles characterizing the Enskog equation tends to zero.On leave from Department of Mathematics, University of Warsaw, Poland.  相似文献   

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