微秒级时间分辨傅里叶变换红外光谱激发系统研究

本文阐述了自行研制的、与FTIR仪器连接运行的时间分辨FTIR系统,包括光激发和电场激发两套系统。检验和测试了系统的工作参数和性能,获得了微秒-毫秒级时间分辨光谱图。     

Phase modulation of transient evolution of atomic response in open lambda-type system with spontaneously generated coherence

We study the effects of the relative phase, Φ, between the probe and driving fields on the transient evolution of the atomic response from different respects in an open lambda-type system with spontaneously generated coherence. We find that: variation of value of Φ will obviously change the transient evolution process, transient and stationary values of gain, absorption and dispersion but has no any effect on the transient evolution of populations. For the same value of Φ, the stationary gain without inversion (GWI) when the incoherent pumping exists is much larger than that when the incoherent pumping is absent, the time needed to reach at the stationary state when the incoherent pumping exists is much shorter than that when the incoherent pumping is absent. The initial condition varying has remarkable effects on the phase-dependent transient evolution process, transient value of GWI but doesn’t vary size of stationary value of GWI. Varying the ratio C of the atomic injection rates and exit rate γ₀ has evident effects on the phase-dependent transient evolution process, transient and stationary values of GWI. Our study result shows that the transient evolution of the atomic response in the open system presents some considerable difference from that in the corresponding closed system, specially in the open system we can get much larger GWI than that in the corresponding closed system. In addition, we give a brief discussion about effects of the relative phase on the transient evolution of the atomic response in the open system without SGC, and obtain some results much different from those obtained in the open system with SGC.     

控制器组件γ瞬时辐射效应研究

瞬时电离辐射在电子器件内部形成的光电流可引起器件输出扰动,导致电路中部分器件受电源、输入信号及自身产生光电流扰动的多重影响,而单独对器件进行试验无法反映瞬时辐射输出扰动在电子组件系统中的传递影响。为此对由DC/DC、稳压器、单片机CPU,FPGA等组成的控制器组件在2.8105~1.7107 Gy(Si)/s的范围内开展了瞬时辐射效应的试验研究。试验中对组件功能和器件参数的测试结果表明,在较小的瞬时剂量率下,部分器件输出受到影响,但组件功能正常;较大剂量率时,所有器件均受影响,且组件功能中断。同时观测到瞬时辐射形成的扰动信号在器件间传输现象。     

Incoherent pump influence on the transient gain in a V-type system with spontaneously generated coherence

We study the influence of the incoherent pump field on the transient response of a three-level V-type system with two near-degenerate excited states. In this system due to interaction of the field with the vacuum an interference term appears, the spontaneously generated coherence term. We find that due to the incoherent pump the transient proprieties of the atomic system can be significantly modified. The enhancement of the transient gain can be obtained for proper values of the rate of the incoherent pump field and relative phase between the two fields.     

Collapse of spatiotemporal chaos

The transient nature of spatiotemporal chaos is examined in reaction-diffusion systems with coexisting stable states. We find the apparent asymptotic spatiotemporal chaos of the Gray-Scott system to be transient, with the average transient lifetime increasing exponentially with medium size. The collapse of spatiotemporal chaos arises when statistical spatial correlations produce a quasihomogeneous medium, and the system obeys its zero-dimensional dynamics to relax to its stable asymptotic state.     

Transient transition behaviors of fractional-order simplest chaotic circuit with bi-stable locally-active memristor and its ARM-based implementation

This paper proposes a fractional-order simplest chaotic system using a bi-stable locally-active memristor. The characteristics of the memristor and transient transition behaviors of the proposed system are analyzed, and this circuit is implemented digitally using ARM-based MCU. Firstly, the mathematical model of the memristor is designed, which is nonvolatile, locally-active and bi-stable. Secondly, the asymptotical stability of the fractional-order memristive chaotic system is investigated and some sufficient conditions of the stability are obtained. Thirdly, complex dynamics of the novel system are analyzed using phase diagram, Lyapunov exponential spectrum, bifurcation diagram, basin of attractor, and coexisting bifurcation, coexisting attractors are observed. All of these results indicate that this simple system contains the abundant dynamic characteristics. Moreover, transient transition behaviors of the system are analyzed, and it is found that the behaviors of transient chaotic and transient period transition alternately occur. Finally, the hardware implementation of the fractional-order bi-stable locally-active memristive chaotic system using ARM-based STM32F750 is carried out to verify the numerical simulation results.     

Comparison of transient process between open and closed ladder-type systems with spontaneously generated coherence and incoherent pumping

We theoretically investigated transient response of open and closed three-level ladder-type atomic system with or without the spontaneously generated coherence (SGC) which could be satisfied with the help of an incoherent pumping. The existence of the SGC effect makes the open and closed system to be distinguished. We compared transient response of weak probe between open and closed system and found that transient properties exhibit different features by adjusting some related parameters, such as the relative phase between probe and coupling fields, the angle between two dipole moments.     

聚合物驱试井分析叠加原理适用性的探索

建立考虑聚合物剪切变稀特性的聚驱试井数学模型,基于矩形网格和井筒周围径向加密的复合网格。采用有限体积方法求得数值解,将数值解与叠加原理得到的注聚井停注压降进行对比。结果表明：叠加原理计算得到的注聚井关井井底压力值远低于数值解,说明叠加原理不能用于聚合物驱试井解释。在实测注聚井压降资料解释中,叠加原理得到的渗透率明显偏低,进一步证明了叠加原理不适合非线性聚驱试井模型,数值方法更加适用于聚驱试井解释。研究结论适用于类似的非线性试井问题。     

Charge-carrier dynamics in polythiophene films studied by in-situ measurement of flash-photolysis time-resolved microwave conductivity (FP-TRMC) and transient optical spectroscopy (TOS)

An in-situ measurement system for flash-photolysis time-resolved microwave conductivity (FP-TRMC) and transient optical spectroscopy (TOS) has been developed to perform simultaneous measurements of photo-induced changes in conductivity and charge-carrier density in an organic thin film. The electric field in the resonant cavity designed for the present system was analysed by electrostatic simulation. Using the present system and the simulated electric field, the photoconductivity and transient absorption in a regioregular poly(3-hexyl thiophene) film were measured using one particular geometry under photon excitation energies of 6.39, 4.98, 3.48, and 2.34?eV. The dynamics of photogenerated charge carriers is discussed in terms of the excitation energy and incident photon intensity. The transient absorption spectrum induced by 3.48?eV light is presented and compared with the TRMC transient.     

线缆系统电磁脉冲效应测量系统研制和试验

分析了实验室瞬态X射线产生的系统电磁脉冲(SGEMP)效应测试所面临的技术问题,提出了解决方法、措施以及实验室模拟瞬态X射线的SGEMP模拟试验方法。通过电子屏蔽、电磁屏蔽、光电隔离、信号对称提取等特殊技术处理,解决了SGEMP效应模拟试验方法和测量系统抗X射线、抗电磁辐射等技术问题,并在大型瞬态X射线模拟源上,测出了瞬态X射线辐照时金属腔内线缆的SGEMP效应波形及幅值。     

束参数瞬态测量在复杂环境中的电磁干扰及兼容设计技术

强流电子束束参数瞬态测量系统在直线感应加速器的复杂电磁环境中会受到强电磁的干扰,主要包括:干扰特性、干扰机理、数学描述、抑制措施、防范措施等,这些干扰既针对电路又针对系统,从而对束参数瞬态测量系统测量的稳定性以及测量数据的有效性都有很大的影响。介绍时间分辨测量系统的原理,分析了瞬态脉冲干扰的成因和抑制方法,给出了束参数测量系统的实验布局和特点,进一步探讨电子器件电性能受瞬态脉冲干扰后的抑制措施,其目的是为了达到减少或消除干扰,破坏干扰信号的传输条件,从而提高整个系统的抗干扰能力及可靠性。通过采用光纤传输控制信号可以很好地传输窄脉冲,减少信号延时抖动,以达到高速信号的可靠稳定传输;利用紧凑嵌入式方法,提高了抗电磁干扰的能力,可以更好保护测量系统电子器件,提高整个系统的抗干扰能力。     

ADS瞬态分析中的概率论-确定论耦合方法

针对加速器驱动次临界系统(ADS)瞬态问题,采用预估校正改进准静态方法(PCQS)处理时空中子动力学方程中的时间自变量,采用蒙特卡罗方法处理相应的空间-角度-能量自变量,重点解决了低次临界度下模拟计算不稳定的问题,验证了TWGIL-Seed-Blanket动力学基准问题和小型模拟ADS问题,得到瞬态过程的功率变化结果,与基于其他方法的程序比较,经初步验证取得了较好结果,证明了该耦合方法可行。     

Active control of intermittent noise in a room

I.IntroductionThereverberantnoisesmaybereducedwithanactivenoisecontrol(ANC)systcmformedbyacornermicrophonc-amplifier-1oudspcakersystemina.oom.lllThismeth-odbascdonthenormalmodccancelingprincip1chasalreadybeenclarifiedbothinthco-ryandexperimcnts,andthclimitationandpotcntialityofitsapp1icationalsodiscussedinapreviouspaper.Thediscussionsinthepastlimitedmost1ytothesteadyconditionofnoiscfield,andthisisextendedtothetransientcondihoninthcprcsentwork,viz.thein-llucnceofthecornerANCsystemwhenthenois…     

Transient gain property of a weak probe field in an asymmetric semiconductor coupled double quantum well structure

The transient gain property of a weak probe field in an asymmetric semiconductor coupled double quantum well structure is reported. The transient process of the system, which is induced by the external coherent coupling field, shows the property of no inverse gain. We find that the transient behavior of the probe field can be tuned by the change of tunneling barrier. Both the amplitude of the transient gain and the frequency of the oscillation can be affected by the lifetime broadening.     

Phase control of light amplification in steady and transient processes in an inverted-Y atomic system with spontaneously generated coherence

We investigate the effects of spontaneously generated coherence （SGC） on both the steady and transient gain properties in a four-level inverted-Y-type atomic system in the presence of a weak probe, two strong coherent fields, and an incoherent pump. For the steady process, we find that the inversionless gain mainly origins from SGC. In particular, we can modulate the inversionless gain by changing the relative phase between the two fields. Moreover, the amplitude of the gain peak can be enhanced and the additional gain peak can appear by changing the detuning of the coupling field. As for the transient process, the transient gain properties can also be dramatically affected by the SGC. Compared to the case without SGC, the transient gain can be greatly enhanced with completely eliminated transient absorption by choosing the proper relative phase between the two fields. And the inverted-Y-type system with SGC can be simulated in both atomic and semiconductor quantum well systems avoiding the conditions of SGC.     

How often are chaotic transients in spatially extended ecological systems?

A traditional assumption in quantitative ecology is that the asymptotic state of the model determines what can be observed in the evolution of the system. It is suggested, however, that irregular transient behaviors may be more relevant than the long term behaviors. Here we investigate how often transient dynamics can be expected in spatially extended ecological systems. Our study suggests that although chaotic transient dynamics indeed exist, sustained dynamics may be more prevalent than transient ones due to the high dimensionality of such systems.     

基于RELAP5的池式研究堆自然循环瞬态计算

反应堆的自然循环能力是其固有安全性的一项重要特征参数,利用RELAP5/Mod 3.4程序计算了JRR-3M池式研究堆在无应急冷却系统和有应急冷却系统条件下失去场外电源的事故工况,分析了冷却剂流动方向反转过程中的瞬态自然循环能力,并得到了最大自然循环载热能力。计算结果表明:应急冷却系统的投入明显地降低了燃料和冷却剂的温度,提高了反应堆的安全性;当衰变功率降低至590 kW时关闭辅助泵,利用自然循环能力可使反应堆达到安全状态。通过此研究堆的自然循环能力计算,验证了计算模型、计算方法的可行性,可进一步应用于此类型的研究堆。     

Complex transient dynamics of hidden attractors in a simple 4D system

A simple four-dimensional system with only one control parameter is proposed in this paper. The novel system has a line or no equilibrium for the global control parameter and exhibits complex transient transition behaviors of hyperchaotic attractors, periodic orbits, and unstable sinks. Especially, for the nonzero-valued control parameter, there exists no equilibrium in the proposed system, leading to the formation of various hidden attractors with complex transient dynamics. The research results indicate that the dynamics of the system shows weak chaotic robustness and depends greatly on the initial states.     

Effects of relative phase on transient evolution in an open resonant ladder-type atomic system

In an open ladder-type resonant atomic system, variation in relative phase between probe and driving fields does not affect the transient evolution of populations, but it has remarkable effects on gain and dispersion of the probe field. No matter whether an incoherent pump is present or absent, transient and stationary gains without inversion (GWI) always can be obtained by choosing an appropriate value of the relative phase. When the incoherent pump is absent,the values of transient and stationary GWIs are much larger and the time interval required to reach the stationary value is longer than those when the incoherent pump is present. Varying the exit rate and the ratio between injection rates can obviously change the phase-dependent GWI. In addition, in the transient evolution process, the phenomenon of high dispersion (refractive index) without absorption occurs at some values of relative phase. In the corresponding closed system, the stationary GWI can be obtained by choosing an appropriate value of relative phase only when incoherent pump exists, moreover the gain is smaller than that in the open system.     

强流电子束时间分辨系统瞬态脉冲干扰的抑制

强流电子束时间分辨测量系统在直线感应加速器(LIA)环境中会受到一些短暂的高能脉冲干扰,这些瞬态脉冲干扰既针对电路又针对测量系统,这对测量系统电子设备危害很大。介绍了时间分辨测量系统的原理,分析了瞬态脉冲干扰的成因和抑制方法,给出了束参数测量系统的实验布局和特点,分析瞬态脉冲干扰对LIA中测量系统电子器件电性能的影响和变化规律,并进一步探讨电子器件电性能受瞬态脉冲干扰后的抑制措施。通过采用光纤传输控制信号的措施,能很好地传输窄脉冲,信号延时抖动小,达到了高速信号的可靠传输要求,利用紧凑嵌入式方法,提高了抗电磁干扰的能力,这样可以更好地保护束参数测量电子器件,提高了整个系统的抗干扰能力及可靠性。