基准平台的控制电路和系统的模拟机仿真

本文对重力仪平台中间跟踪系统采用双极性脉宽调制(PWM)电路的优点、原理和设计要点作了论述,并导出有关特性的模型.在此基础上,对该系统按力矩跟踪系统方案在模拟计算机上进行了仿真,得出最佳的动态性能指标.     

Detection of the translational oscillations of the Earth＇s solid inner core based on the international superconducting gravimeter observations

Based on the 21 series of the high precision tidal gravity observations recorded using superconducting gravimeters (SG) at 14 stations distributed globally (in to-tally about 86 years), the translational oscillations of the Earth抯 solid inner core (ESIC) is detected in this paper. All observations are divided into two groups with G-Ⅰ group (8 relatively longer observational series) and G-Ⅱ group (13 relatively shorter observational series). The detailed correc-tions to minute original observations for each station are carried out, the error data due to the earthquakes, power supply impulses and some perturbations as change in at-mospheric pressure and so on are carefully deleted for the first step, the gravity residuals are obtained after removing further synthetic tidal gravity signals. The Fast Fourier Transform analysis is carried out for each residual series, the estimations of the product spectral densities in the sub-tidal band are obtained by using a multi-station staking technique. The 8 common peaks are found after further removing the remaining frequency dependent pressure signals. The eigen-periods, quality factors and resonant strengths for these peaks are simulated. The numerical results show that the discrepancies of the eigenperiods for 3 of 8 peaks, compared to those of theoretical computation given by Smith, are only 0.4%, -0.4% and 1.0%. This coincidence signifies that the dynamical phenomenon of the Earths solid inner core can be detected by using high precision ground gravity observations. The reliability of the numerical computation is also checked, the spectral peak splitting phenomenon induced by Earths rotation and ellipticity is preliminary discussed in this paper.     

微波频率时间标准的研究

在微波，已能用１×１０－１３的准确度确定某个频率；这表示原子的能级差可以这么精确。铯钟是原子时间得以定义的根据。氢钟的谱线极窄，能级图简单，稳定度高（在１０－１３至１０－１５之间）。另一方面，利用宏观物理效应也能做出高准确度、高稳定度的微波频标——超导腔稳频振荡器（ＳＣＳＯ）即为显著的实例。超导腔的质量因数最佳者可达１０１１，ＳＣＳＯ的短期稳定度竟可达６×１０－１６。令人惊叹的成就又开辟了应用前景     

非晶态Bi_(2.2)Sr_(1.8)CaCu_(1.2)Li_(0.8)O_y晶化的正电子湮没谱研究

Bi-Sr-Ca-Cu-O系超导氧化物通过熔体快速凝固极易生成非晶态,这种非超导的非晶态通过合宜的后续热处理,可以转变为具有高超导转变温度Tc的晶态相,其Tc和相似成分的粉末烧结体相近。非晶Bi系氧化物具有致密度高,成分均匀并可成型为各种形状等优点,经由非晶态转变为高超导性能的晶态已成为某些潜在的实用超导材料制备工艺的基础如