再谈"暂态过程三要素法应用中的关键问题"

从一阶微分方程入手,对若干典型的由多个电容和电感构成的电路进行分析,总结出一阶电路的界定方法及其时间常量的求法原则.     

卷积积分与三要素法在电路分析中的应用

一阶电路在任意激励下的零状态响应，既可以用卷积积分法，也可以用三要素法进行分析与计算．本文通过对具体电路的计算，以阐明这两种方法的特点．     

实验中的暂态过程

实验中的暂态过程李文胜（淮北煤炭师院物理系，２３５０００）由于机械部分质量、惯量的存在，电路中电感、电容的存在，并且也由于能源功率的限制，使得运动部件的加速度不会很大，速度和位移不会瞬间变化，而要经历一段时间，要有一个过程，才能进入稳态过程，这种过程...     

卷积积分与三要素法在电路分析中的应用

一阶电路在任意激励下的零状态响应，既可以用卷积积分法，也可以用三要素法进行分析与计算，本文通过对具体电路的计算，以阐明这两种方法的特点。     

三要素法适用范围的拓展

从一阶电路微分方程出发，找出其全响应的一般表达式，使之适用于求解各种激励信号下的响应。     

任意激励下一阶电路的积分解及三要素法

给出任意激励下一阶电路的积分解,并由此导出三要素法公式。     

RLC暂态过程震荡峰位对测量时间常量的影响

在测量RLC电路暂态过程时间常量时,通常测量电容电压的欠阻尼震荡峰值间接测量时间常量.欠阻尼震荡峰值往往简单地近似为sin(ωdt+φ)=±1时的电容电压值.讨论了这一近似峰位与准确峰位的区别与联系,结果表明由近似峰位得出的时间常量不存在近似性,与由准确峰位得出的时间常量是一致的.     

基于Matlab的电路暂态过程分析

运用Matlab进行电路暂态过程分析,编程简便,方法易学,可将用复杂函数表达的推导、计算结果以直观、形象的图象表示出来,便于学生理解和掌握。该方法可推广到电工学其他课程的教学中,也可用来制作相应的电子教案。     

测定RLC串联电路暂态过程的临界电阻

从RLC串联电路方程及其初始条件出发、推导出电路欠阻尼状态下阻尼电阻与振幅、阻尼度之间的关系式，用最小二乘法对测量数据进行线性回归，测量了临界阻尼电阻。     

RLC串联电路暂态过程的演示

介绍一种能显示ＲＬＣ串联电路暂态过程中三种不同情况下Ｒ和Ｃ上的电压波形的演示实验．     

RC电路暂态过程的探究式实验教学

运用探究式实验教学方法，由学生自行设计完成了RC电路的暂态过程实验．实践证明，探究式教学有利于培养学生的创新能力。     

电路暂态过程的教学研究

从解法、解的形态和时间常数三个方面研究了电路暂态过程的教学。     

利用暂态过程测量互感系数

介绍了在电源输出为方波时,分别利用RL电路的暂态过程和RLC电路的暂态过程测定互感器互感系数的方法.     

The flavour liquid state and Hund‘s rule effects in spin systems with orbital degeneracy

In order to understand the properties of the spin system with orbital degeneracy, we first generalize the linearized semiclassical spin wave method for the SU(2) generators into the SU(4) case, and then investigate the elementary excitations of the orbital-spin systems in the SU(4) limit. The results show that, due to the reduction of the dimensionality of the excitations, the ordered state of the SU(4) spin-orbital model is unstable. Secondly, we study the effects of the Hund interaction on the flavour liquid state of the system. Our mean-field results suggest that, for a small Hund interaction, the flavour liquid state is still stable against the generalized spin-density wave state, but with sufficient deviation from the SU(4) limit, the long-range order may be attained in two-dimensional systems. Finally, the implications for the experimental observations on the material LiNiO₂ are discussed.     

Modification of laser-induced state in atomic attosecond transient absorption by the XUV pulse pair

Attosecond transient absorption(ATA) has been developed as an all-optical technique for probing electron dynamics in matter.Here we present a scheme that can modify the laserinduced state and the corresponding ATA spectrum via excitation by a pair of XUV attosecond pulses and by a time-delayed mid-infrared(MIR) laser probe.Different from the scheme of the electronic excitation by a single XUV attosecond pulse,the application of a pair of XUV pulses provides extra degrees of freedom,such as the t...     

RLC串联电路暂态过程时间常数的测量与修正

本文分析了RLC串联电路暂态过程时间常数τ的实验测量值与理论值偏差的原因,以频率为振荡频率的正弦波代替欠阻尼振荡波,测出电路电容和电感上的损耗电阻,对时间常数的理论值进行修正,可使τ的理论修正值与实验测量值基本吻合。     

On the constituent counting rule for hard exclusive processes involving multi-quark states

At high energy,the cross section at finite scattering angle of a hard exclusive process falls off as a power of the Manderstam variable s.If all involved quark-gluon compositions undergo hard momentum transfers,the fall-off scaling is determined by the underlying valence structures of the initial and final hadrons,known as the constituent counting rule.In spite of the complication due to helicity conservation,it has been argued that when applied to exclusive process with exotic multiquark states,the counting rule is a powerful way to determine the valence degrees of freedom inside hadron exotics.In this work,we demonstrate that for hadrons with hidden flavors,the naive application of the constituent counting rule is problematic,since it is not mandatory for all components to participate in hard scattering at the scale s1/2.We illustrate the problems in the viewpoint based on effective field theory.We clarify the misleading results that may be obtained from the constituent counting rule in exclusive processes with exotic candidates such as Z_c~±(cd/cu),Z_b~±(bd/bdu),X(3872),etc.     

The transient processes in multi-pulse nitrogen-14 NQR

It has been demonstrated that transient processes, observed in a single crystal of NaNO₂ acted upon by pulse sequences MW-2 and MW-4 and their modifications with 180° flip angle of the pulses (Solid State Nucl. Magn. Resonance 10 (1997) 63; Sov. Phys.—JETP 88(5) (1999) 1580), which manifest themselves in the oscillating form of the NQR signals envelope, can be explained in the frames of a two-particle model. It has been proved that the nature of echo signals in the effective field of multi-pulse sequences received by the inversion of the phase of the sequence pulses or by introducing an additional 180° pulse is connected with re-focusing of accumulated digressions of the flip angle from the ideal 180° pulse. Experimental results of observing single and multiple echoes in a number of powdered nitrogenated substances in the effective field of various sequences at room temperature have been presented.