基于记忆合金的大承载低冲击解锁机构设计与试验研究

为满足航天器大承载、低冲击、快速响应的连接与分离需求,提出一种基于记忆合金驱动、具有非自锁传动特性和多级增力结构形式的解锁机构,对解锁触发系统和承载传动系统设计方法进行了研究,通过理论分析、仿真和测试,确定了影响记忆合金驱动性能和非自锁梯形螺纹副设计的关键参数。试验结果表明,该解锁机构承载能力强,解锁冲击小,响应快速,解锁时间同步性好,可重复使用,在航天器连接与分离系统中有很大的应用潜力。

Population Inversion of a V-type Three-Level Atom due to the Effect of Cavity-Induced Quantum Interference

A cavity-modified master equation is derived for a coherently driven V-type three-level atom coupled to a singlemode cavity in the bad cavity limit.The influences of the cavity-induced quantum interference on the steady-state populations are analysed.We show that the population inversion can occur due to the effect of cavity-induced quantum interference.

A Study on Radar Cross Section of the Two-Dimensionally Fractal Rough Surface

The analysis of the RCS from the rough sea and ground surface is made. The two dimensionally band limited fractal function is used to model the sea and ground surface, the scattered electromagnetic field is calculated by using Kirchhoff approximation. The validity of this result is assured by some references, which indicates that the methods are reliable.

Effects of Detunings on Dynamically Induced Irreversibility in Coherently Driven Systems

Effects of detunings on dynamically induced irreversibility is studied for coherently driven V systems in which there is no conventional source of irreversible population pumping.For atomic barium(γ1/γ2=400>>1,whereγ1 andγ2 are the rates of the spontaneous decay from the excited states 6s6p^(1)P_(1)and 6s6p^(3)P_(1)to the ground state 6s^(2)^(1)S_(0),respectively),the strong irreversibility is found to lead to a maximum inversion of 0.77[only 0.1 in Phys.Rev.Lett.71(1993)4311].The maximum population inversion requires relatively strong Gelds coupled respectively to two transitions,a disparity in two atomic decay rates,and the atom-field detunings of opposite signs.However,it is also shown that even in the cases where two detunings have the same sign,or where two decay rates are equal,population inversion takes place.

Absorption Spectrum of a Driven Two-Level Atom in a Tunable Cavity with Injected Squeezed Vacuum

The absorption spectrum of a driven two-level atom in a frequency tunable cavity with injected squeezed vacuum is investigated. The line shape of the spectra depends on the relative phase between the driving field and the squeezed vacuum, and the frequency detuning between the driving field and the cavity mode. Line narrowing and probe gain can occur and be enhanced by adjusting the phase and detuning.

Squeezed Quantum-Beat Laser Without Inversion

A quantum-beat laser without inversion is proposed for producing two-mode suqeezing.Using the dressed-atom-dressed-mode approach,the master equation is derived and the variances in the sum mode intensity and in the relative amplitude and phase are calculated.When the laser is operated well above threshold,the intensity fluctuations in the sum mode are reduced below the shot noise limit with an optimum Mandel parameter of-0.5.At the same time,the fluctuations in the relative amplitude and phase are retained at their vaccum noise levels.

Effects of Pump Phase Noise on the Linewidth of a Λ-Laser Without Inversion: Linewidth Reduction

The effects of the pump phase fluctuation on aΛ-laser with and without inversion are investigated.It is shown that the pump phase fluctuation can reduce the linewidth of the laser without inversion.It is also shown that,when the system exhibits a transition from lasing without inversion to lasing with inversion,the laser linewidth can still be reduced.

Squeezed Cascade Two-Quantum-Beat Lasers

Noise squeezing of intensity difference between the pair of sum modes may be generated in a cascade laser of A and U quantum-beats.The best achievable squeezing is up to 50%below the shot noise limit.This new kind of squeezed lasers has potential for quantum communications and precision measurements.