激发态上钠原子的相干囚禁

对Ｖ型三能级原子系统与双激光场同时共振产生的能级相干效应进行了研究。计算了各能级上的粒子数分布，实验观测到在相干驻波场中的钠原子被囚禁在激发态上的现象。对比和分析有无干涉效应存在时３Ｓ１／２，Ｆ＝２态上布居数的变化情况。     

高分辨率高灵敏度分子光谱的激光磁共振方法研究

激光磁共振是高分辨率高灵敏度的激光光谱方法之一,研究的主要对象是稳态顺磁分子、自由基分子及分子激发态的振转光谱,获得这些分子能级信息与参数,在化学反应动力学、分子激发态动力学、燃烧化学与物理和大气污染有着广泛的用途。这项工作在国外始于七十年代初,在国内,我们于1984年首先开始了这项工作。做了一系列稳定分子、自由基分子基态和Hg原子激发态的研究工作。目前,我们的工作仍然处于领先水平。     

受驱动光学系统多光子三稳态量子理论

本文描述在外场驱动下,环形腔中N个全同双能级原子和腔模相互作用系统与热库的耦合作用。研究注入信号频率、单模腔场频率、双能级原子非共振(吸收与色散并存)情况的n光子跃迁过程。已有人讨论了系统的态方程,但未仔细研究其稳定行为。本文分析了失谐情况下多光子稳态方程的稳定性。发现光学三稳态,这一现象仅出现在失谐量取一定范围内。系统的稳定性随着腔的质量(良腔、普通腔、劣腔)的不同而出现较大的变化。调节系统的耦合参数和失谐量,可以变动光学三稳态工作区。我们认为,从理论和实验来研究这一光学三稳现象都很有意义。     

Ba原子6s2 1S0 - 6s6p3P1跃迁Hanle效应实验研究

Ba原子是光频标的候选者之一,对其进行有效的激光冷却与囚禁需要相关能级的寿命和跃迁几率的信息。Ba原子激发态6s6p 3P1能级在激光冷却实验中很重要,通过Hanle效应实验测量了这一能级的寿命和自发辐射率,从理论和实验上研究了探测激光有限线宽和光强对Ba原子基态6s2 1S0与激发态6s6p 3P1之间跃迁（波长791 nm）的Hanle效应的荧光信号的影响。在考虑了激光线宽和光强因素后所得到的激发态6s6p 3P1的能级寿命和自发辐射率与其他方法给出的结果很好符合。     

紫外激光激发原子束Pb6s~26p~2 ~3P_0—6s~26p7s~3p_1~0跃迁

利用原子束光谱方法,测量包括激发态、高激发态能级位置、跃迁几率、能级寿命以及离化截面等诸多的原子数据,是极其优越的。因而原子束装置在国外众多的光谱实验室中广泛地被使用着。我们建立了一台原子束装置,其温度最高可达1500℃,极限真空度为2×10~-Torr。在此装置上我们装配了原子荧光探测和离化探测配件,连同实验室中YAG泵浦染料激光器系统,构成了一套完整的原子光谱实验装置。使用这一装置,产生了铅原子束,并且实     

钾原子能量积聚速率系数和跃迁截面的测量方法

能量积聚（Ｅｎｅｒｇｙ ｐｏｏｌｉｎｇ,下面简称 ＥＰ）是当激发态的粒子相互碰撞的时候,发生能量碰撞转移,一个激发态粒子到达更高能级,而另一个激发态回到基态．根据能量守恒原理,更高激发态的能级应该在二倍于产生它的激发态的能级的附近,或者说近似等于产生它的两激发态粒子的能级之和,微小的能量差异,转变成了粒子的动能或者使粒子动能减少,即使粒子冷却．这就使ＥＰ效应的研究更加有趣和有意义． 对于钾原子,其 ＥＰ过程可以用下式表示。 Ｋ（４ＰＪ）＋ Ｋ（４ＰＪ） － Ｋ（４Ｓ） ＋ Ｋ（ｎｌ）＋△Ｅ,其中末态ｎｌ＝…     

铀原子高激发态寿命测量

本文报道用三波长三步光电离法测量铀原子高激发态奇能级寿命的技术和结果。     

Mollow谱线与电磁诱导透明和吸收的叠加

对双耦合场作用下的Λ型三能级系统的透明和吸收特性进行了理论研究。在二能级系统中,强耦合场和探测场同时作用于激发态能级和基态能级之间,探测吸收曲线上出现Mollow谱线。在激发态能级和基态的另一精细结构能级之间引入另一个耦合场,构成Λ型三能级系统。在这个双耦合Λ型三能级系统中,出现了一些新的量子相干现象。结果表明,探测吸收谱线中不仅有Mollow现象,还出现了电磁诱导透明(EIT)和电磁诱导吸收(EIA)。分析了EIT和EIA的位置随双耦合场参数的变化规律,并用缀饰态理论做出了解释。     

锁模激光相干激发原子的超窄共振效应

实验发现,锁模激光脉冲序列激发原子,能产生超窄共振效应。为解释这类现象我们提出一个相干激发理论模型,确认超窄共振的实质是:两个激光模同一时刻分别激发原子Na的DI线的两对超精细结构子能级时,产生尖锐的共振干涉效应。 本文采用全量子理论。为考虑不同原子间碰撞弛豫效应,令总系统由原子A、光场和热库(缓冲气体)组成。以多模相干态表示锁模激光场。利用预解算符和投影算符技巧表示系统     

双色三光子共振电离测量钐原子高激发态4f~6s7S新能级

本文报道用双色三光子共振电离法测量钐原子高激发态78个新能级。这些新测定的偶宇称能级属于4f~66s7S电子构型,位于33477～37758cm~(-1)能量范围。     

Design of fast-response current controller using d-q axis crosscoupling: application to permanent magnet synchronous motor drive

A new current controller, which has both fast transient response in the transient state and high accuracy in the steady state, is proposed. In this scheme, a reference modification part is incorporated with the generally used synchronous frame proportional integral (PI) controller for the fast transient response. Through experimental results, it is observed that the proposed controller has much less transient time than the conventional synchronous PI regulator     

Semiconductor steady state defect effective Fermi level and deep level transient spectroscopy depth profiling

The widely used deep level transient spectroscopy (DLTS) theory and data analysis usually assume that the defect level distribution is uniform through the depth of the depletion region of the n-p junction. In this work we introduce the concept of effective Fermi level of the steady state of semiconductor, by using which deep level transient spectroscopy depth profiling (DLTSDP) is proposed. Based on the relationship of its transition free energy level (TFEL) and the effective Fermi level, the rules of detectivity of the defect levels are listed. Computer simulation of DLTSDP is presented and compared with experimental data. The experimental DLTS data are compared with what the DLTSDP selection rules predicted. The agreement is satisfactory.     

Steady‐State and Transient Behavior of Organic Electrochemical Transistors

In recent years, organic electrochemical transistors (OECTs) have emerged as attractive devices for a variety of applications, particularly in the area of sensing. While the electrical characteristics of OECTs are analogous to those of conventional organic field effect transistors, appropriate models for OECTs have not yet been developed. In particular, little is known about the transient characteristics of OECTs, which are determined by a complex interplay between ionic and electronic motion. In this paper a simple model is presented that reproduces the steady‐state and transient response of OECTs by considering these devices in terms of an ionic and an electronic circuit. A simple analytical expression is derived that can be used to fit steady‐state OECT characteristics. For the transient regime, comparison with experimental data allowed an estimation of the hole mobility in poly(3,4‐ethylenedioxythiophene) doped with poly(styrene sulfonate). This work paves the way for rational optimization of OECTs.     

New hybrid fuzzy controller for direct torque control induction motor drives

A new hybrid fuzzy controller for direct torque control (DTC) induction motor drives is presented in this paper. The newly developed hybrid fuzzy control law consists of proportional-integral (PI) control at steady state, PI-type fuzzy logic control at transient state, and a simple switching mechanism between steady and transient states, to achieve satisfied performance under steady and transient conditions. The features of the presented new hybrid fuzzy controller are highlighted by comparing the performance of various control approaches, including PI control, PI-type fuzzy logic control (FLC), proportional-derivative (PD) type FLC, and combination of PD-type FLC and I control, for DTC-based induction motor drives. The pros and cons of these controllers are demonstrated by intensive experimental results. It is shown that the presented induction motor drive is with fast tracking capability, less steady state error, and robust to load disturbance while not resorting to complicated control method or adaptive tuning mechanism. Experimental results derived from a test system are presented confirming the above-mentioned claims.     

Band structure anisotropy effects on the hole transport transient in 4H–SiC

We study the role of band structure anisotropy on the hole transport in 4H–SiC during the transient regime. For the same strength of the applied electric field, the drift velocity overshoot of the hole is stronger and reaches steady state later when the field is applied perpendicular to the c-axis, than when the field is in the c-axis direction. In both cases, the time for the hole drift velocity and mean energy to reach steady state is under 50 fs, depending on the electric field strength, and are one order of magnitude shorter than the time for the electron drift velocity and mean energy to attain the steady state.     

Analysis of transient and steady-state processes in the series (resonant)inverter

This paper deals with analysis of the transient and steady-state processes in series (resonant) inverters. Sets of differential and difference equations governing the transient and steady state processes are obtained and solved. The solution is found in closed analytical form. Theoretical and experimental results, both for transient and steady-state conditions, are compared and satisfactory agreement shown.     

倒立摆状态反馈极点配置与LQR控制Matlab实现

为了实现对绝对不稳定的非线性多变量倒立摆系统的控制,采用了状态反馈极点配置和LQR控制2种方法。状态反馈极点配置是将多变量系统的闭环系统极点配置在期望的位置上,从而使系统满足瞬态和稳态性能指标。LQR算法是在一定的性能指标下,利用最少的控制能量,来达到最小的状态误差。通过Matlab软件仿真实验,发现2种控制方法对于倒立摆这种不稳定的系统有一定的控制作用,证明了两种控制方案的可行性和有效性。仿真表明二次型最优控制有较小的振荡和超调量,对系统有更好的控制效果。     

基于FWCM的非线性动态电路时域稳态模拟

本文提出一种基于快速小波配置法（ＦＷＣＭ）的非线笥动态电路时域稳态模拟方法。该方法可以对电路瞬态响应过程用大步长（低阶小波）模拟,而对稳态响应过程用小步长（高阶小波）模拟,从而避免了为得到电路稳态响应而在瞬态响应时期花费的大量的模拟时间。并且,该方法具有较低的计算复杂度。一些模拟结果证明,本文的方法是一种十分有效的方法。     

High field transport in GaAs,InP and InAs

Calculations of the steady state and transient electron drift velocities and impact ionization rate are presented for GaAs, InP and InAs based on a Monte Carlo simulation using a realistic band structure derived from an empirical pseudopotential. The impact ionization results are obtained using collision broadening of the initial state and are found to fit the experimental data well through a wide range of applied fields. In InP the impact ionization rate is much lower than in GaAs and no appreciable anisotropy has been observed. This is due in part to the larger density of states in InP and the corresponding higher electron-phonon scattering rate. The transient drift velocities are calculated under the condition of high energy injection. The results for InP show that higher velocities can be obtained over 1000–1500 Å device lengths for a much larger range of launching energies and applied electric fields than in GaAs. For the case of InAs, due to the large impact ionization rate, high drift velocities can be obtained since the ionization acts to limit the transfer of electrons to the satellite minima. In the absence of impact ionization, the electrons show the usual runaway effect and transfer readily occurs, thus lowering the drift velocity substantially.     

Analysis of the Transient and Steady-State Processes in the Parallel Inverter

This paper deals with the analysis of the transient and steady-state processes in parallel inverters. A set of difference equations, describing the currents and voltages during transient and steady state is obtained and solved. The solution is found in closed form. The roots of the characteristic equations are examined and possible types of transients are discussed. Theoretical and experimental results both for transient and steady-state conditions are compared and satisfactory agreements are found.