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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.
The investigation was made of the dependence of the intensity of Tl, Ga, Mo, Mg, Mn, Sn, Bi, Ni, Zn, Pt and Au spectral lines and the plasma parameters (temperature T, electron concentration ne, degree of 6 ionnization α) from concentration of lithium additive.  相似文献   

3.
In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required.  相似文献   

4.
干涉仪系统传递函数测量及影响因素的分析   总被引:1,自引:0,他引:1  
邓燕  柴立群  许乔  徐建程  张宁 《光学技术》2006,32(5):741-743
波前功率谱密度(PSD)被用于评价惯性约束聚变(ICF)激光驱动器光学元件中频段的波前误差。干涉仪对PSD较高空间频率分量的测量存在失真效应,可通过干涉仪系统传递函数(STF)的检测标定来获得真实的波前PSD分布。采用台阶板位相比较法测得大口径菲索相移干涉仪检测系统在透射和反射检测情形下的传递函数。对传递函数测试算法进行了比较分析,明确了干涉仪系统zoom倍率的改变等因素对传递函数测量的影响,为波前PSD的准确检测奠定了基础。  相似文献   

5.
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   

6.
We study the Cauchy problem for the Whitham modulation equations for increasing smooth initial data. The Whitham equations are a collection of one-dimensional quasi-linear hyperbolic systems. This collection of systems is enumerated by the genus g=0,1,2, ... of the corresponding hyperelliptic Riemann surface. Each of these systems can be integrated by the so-called hodograph transformation introduced by Tsarev. A key step in the integration process is the solution of the Tsarev linear overdetermined system. For each g>0, we construct the unique solution of the Tsarev system, which matches the genus g+1 and g–1 solutions on the transition boundaries.  相似文献   

7.
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   

8.
非简谐振动对石墨烯杨氏模量与声子频率的影响   总被引:1,自引:0,他引:1       下载免费PDF全文
程正富  郑瑞伦 《物理学报》2016,65(10):104701-104701
在哈里森键联轨道法框架下, 考虑到原子的短程相互作用和原子的非简谐振动, 应用固体物理理论和方法, 得到了石墨烯的力常数、杨氏模量、扭曲模量、泊松系数以及声子频率随温度的变化关系, 探讨了非简谐振动对它们的影响. 结果表明: 1)杨氏模量与声子频率等随温度变化并遵从一定的规律, 其中力常数、杨氏模量、扭曲模量随温度升高而增大, 但变化较小; 声子频率随温度升高而增大但变化较快; 泊松系数随温度升高而较快地减小; 2)石墨烯原子具有沿键长方向的纵振动和垂直键长方向的横振动, 但以纵振动为主, 纵振动的非简谐效应远大于横振动, 横振动的简谐系数ε0' 和第二非谐系数ε2' 均小于纵振动的相应值ε02; 比值为ε00' ≈ 8.477,ε22' ≈ 156; 3)若不考虑非简谐振动项, 则石墨烯的力常数、杨氏模量和扭曲模量、泊松系数、声子频率均为常量, 与实验不符合; 同时考虑到原子的第一、二非简谐振动项后, 它们均随温度升高而变化, 而且温度愈高, 原子振动的非简谐效应愈显著. 本文的结果与文献的实验结果符合较好.  相似文献   

9.
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   

10.
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   

11.
在格点上构造计算胶球质量的新途径   总被引:1,自引:0,他引:1  
发展了一种为了计算胶球质量而构造格点算符的新途径.基于所选用算符的连续极限与状态量子数JPC两者之间的联系,状态的自旋就可以在数值模拟中唯一和直接地被确定下来.进而,这一途径可以被应用于计算任意自旋J的胶球质量.在淬火近似下,给出在SU(3)纯规范场中0++态和2++态胶球质量的初步结果,它们分别是1754(85)(86)MeV和2417(56)(117)MeV.  相似文献   

12.
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   

13.
示波器电子运动规律与波形显示关系研究   总被引:2,自引:1,他引:1  
本文详细地论述了示波管荧光屏上的显示波形与电子运动规律、波形周期与扫描电压周期间的关系,以便帮助学生理解和解决学习示波器原理过程中遇到的疑难、疑惑问题。  相似文献   

14.
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   

15.
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   

16.
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   

17.
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   

18.
通过对三大岩类中15种岩石样本(样本总数目达208块)进行取样测定,获得其密度、磁化率以及波段350~2 500 nm的反射光谱数据。以研究岩石物性(密度及磁化率)与其不同波段反射率相关性,求取了相关系数曲线。根据试验结果曲线,进一步对具有岩石反射率定性及定量探讨岩石密度及磁化率前景的岩石种类及波段进行了总结,并且对几种岩石相关系数曲线的特征进行了归纳。认为通过岩石反射率间接获取岩石密度及磁化率的研究思路具有一定意义及可行性。  相似文献   

19.
 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.
论Gibbs方程的热力学本性及热力学函数的物理意义   总被引:8,自引:2,他引:6  
贾世忠 《大学物理》2004,23(1):12-15
对Gibbs方程的热力学本性作了再认识,论述了热力学函数U、H、A、G的物理意义,尝试从一般的运动和势能的关系上理解热力学.  相似文献   

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