缺陷红外诊断的热激励方式对比研究

热激励方式的合理选择是保证主动缺陷检测以及定量识别效果的前提。建立了一个用于分析不同热激励方式下缺陷试件红外检测表面温度分布规律的二维导热模型。针对几种常见热激励方式,通过改变加热面积、加热位置及热流密度来改变热激励的施加方式,系统地分析了带有缺陷的试件在施加不同热激励时红外检测表面的温度分布规律,发现在多个相邻边界面施加热激励时可获得较好的缺陷识别加热效果。     

语音信号线性预测模型中的激励源

本文主要阐述了语音线性预测编码中描述声道特性的全极点预测滤波器的几种激励方式,即残余信号激励,多脉冲激励及音调激励的原理和有关性能。对基带提取—高频再生残余信号的激励方式亦作了相应的介绍。     

解析PRT自激励振方式VRC软开关变换电源技术

从正交型变压器PRT的结构和控制技术出发,对先进的自激励振方式VRC软开关变换电源技术进行解析.利用电路图和工作波形图,重点说明自激励振方式VRC的4种控制方式的电路构成原理,简要阐述它们之间的区别、工作原理和实用技术参数.这4种控制方式是:并联谐振频率控制方式、谐振电压脉冲宽度控制方式、升压型电压控制方式和复合控制方式.它们都是基于控制PRT电感量来实现自动稳定输出电压的自激励振方式的软开关变换电源技术.     

高功率电激励CO激光器研究进展

按照激光系统冷却方式和激励方式,介绍了当前高功率电激励一氧化碳激光器器件的研究进展,讨论了不同类型高功率激光器之间的优缺点,以及高功率一氧化碳激光器的应用.     

企业薪酬管理及其信息化应用

进入21世纪,经济全球化和企业管理信息化已经越来越深刻地影响着我国的企业,这也加剧了企业的人才竞争.企业人才战略中最重要的是企业的激励制度,激励制度有多种方式,包括薪酬激励、物质激励及精神激励等.     

红外热成像诊断电路板的动态激励方法

在分析激励方式与电路板热模式的关系和大量实验的基础上，提出了电路状态快速转换的动态激励方法，并对动态激励方法的作用和效果进行了分析及实验，结果表明动态激励对红外热成像诊断能力有很大的提高。     

基于涡流热成像的铁磁材料近表面微裂纹检测

采用涡流热成像技术,对铁磁材料近表面微裂纹进行了检测研究。提出了平行激励热传导方式检测近表面微裂纹的检测方法;数值计算模拟了涡流激励下裂纹处的生热过程,分析了裂纹处的温度分布及其对检测结果的影响;采用平行激励方式对含近表面微裂纹的铁磁材料进行了检测实验,通过提取试件表面温度分布数据,获取其变化速率曲线,实现了对裂纹的检测和识别。结果表明:涡流热成像平行激励方式能够准确地检测到铁磁材料近表面的微裂纹缺陷;选择适当的涡流激励时间有助于提高裂纹处与非裂纹处温度对比,增强检测效果。该方法的研究为近表面微裂纹的检测和定量识别奠定了基础。     

状态激励轻敲模式原子力显微镜的设计与仿真

为轻敲模式原子力显微镜设计了一种激励方式,在带有状态反馈的轻敲模式原子力显微镜基础上,除去原有的外加激励信号而引入一个自动增益控制环节,用于维持状态反馈信号的幅度恒定,并将此信号作为悬臂振动的漱励信号.读激励方式即为状态激励,用于轻跛模式时可称为状态激励轻敲模式原子力显微镜.采用Matlab/Simulink工兵实现了...     

掺镨光纤放大器激励效率的理论分析

对１．３μｍ掺镨光纤放大器的有效激励工作情况进行了理论分析，给出了不同的激励波长，工作模式和单，双向两种激励方式情况下放大器增益的计算结果。     

磁化等离子体填充圆波导激励与耦合方式的研究

对电磁波在磁化等离子中的传播进行了理论分析,通过同轴线的轴向激励和侧向激励两种方式激励与耦合磁化等离子体填充圆波导,并对其中电磁波的传输情况进行了仿真计算,结果表明当尽寸适当时,此波导具有良好的传输性能。     

Electrophysical Parameters and Radiation Spectra of Boron Trichloride Plasma

The electrophysical parameters and radiation spectrum of BCl₃ plasma under a DC glow discharge are analyzed. Data on the gas temperature and reduced electrical field intensity are obtained. It is established that the reduced electrical field intensity in BCl₃ plasma practically does not depend on the discharge current (under a constant pressure); moreover, it appreciably decreases with an increase in the gas pressure (under a constant discharge current). It is revealed that a linear increase in the gas temperature with increasing pressure is caused by increasing the specific power expended in the discharge. The radiation spectra of BCl₃ plasma are presented by atomic and molecular components. It is established that with a growth in the current the radiation intensity increases linearly, which corresponds to the mechanism of direct excitation of radiating states under an electronic impact and it is evidence of a lack of secondary processes.     

Relation Between Discharge Length and Laser Pulse Characteristics in Longitudinally Excited CO2 Laser

A longitudinally excited CO₂ laser pumped by a fast discharge emits a short laser pulse, similarly to TEA and Q-switched CO₂ lasers. We investigated the relation between the discharge length and the laser pulse characteristics to develop a longitudinally excited CO₂ laser producing a high spike laser pulse. We examined discharge lengths of 30, 45, and 60 cm, using the same mirrors and the same excitation circuit with the same input energy. A longer discharge length increased the discharge volume and improved the laser output energy. However, the longer discharge length caused a long discharge formation time (a slow fall time of the discharge voltage) due to the higher discharge impedance, which resulted in a long laser pulse tail. Therefore, the longitudinally excited CO₂ laser had optimum conditions for obtaining a high spike laser pulse effectively.     

Electrical discharge and laser gain characteristics of a coaxialdischarge CO2 laser stabilized by a transverse rotatingmagnetic field

The feasibility of creating laser excitation in a diffusion cooled annular coaxial geometry CO₂ laser by a longitudinal DC electrical discharge stabilized with a rotating transverse magnetic field has been demonstrated. The uniformity of the electrical discharge in the annular cross section could be enhanced considerably with the application of the magnetic field. A peak laser small-signal gain of 0.3 m^-1 was obtained. This scheme could be utilized to construct a compact high-power diffusion cooled CO₂ laser system     

约束放电激励千瓦级基模CO2激光器

本文研究了约束放电激励千瓦级基模CO2激光器。约束放电激励的思想核心是:利用正交或基本正交的电场或者电磁场在阴极位降区附近形成对带电粒子的捕集阱,由此产生对放电过程中从阴极发出的带电粒子的约束作用从而影响整个气体放电激励过程。     

Longitudinal RF excitation of carbon dioxide lasers

Longitudinal RF excitation of CO₂ — Lasers at relatively low radio frequencies in the 100 to 200 kHz range permits an efficient AC to RF conversion in the power supply while maintaining all the advantages of RF excited lasers. Existing tube designs for DC excitations can be easily modified, and peripheral circuitry like laser stabilizers remain useable too. Experimental results for a prototype laser are given.     

Electro-optically Induced and Manipulated Terahertz Waves from Fe-doped InGaAs Surfaces

We demonstrate the presence of dual simultaneous nonlinear mechanisms: field-induced optical rectification (FIOR) and field-induced surge current (FISC) for the generation of terahertz (THz) pulses from p-type and n-type Fe:In_0.53Ga_0.47As surfaces upon excitation with femtosecond laser pulses centered at 800 nm wavelength. Experimental investigations of the dependence of the generated THz waves on the incident angular optical polarization, optical irradiance, and the direction and magnitude of applied electric DC fields give confirming results to the proposed THz generation mechanisms. Applying external DC electric fields in the plane of the incident optical field shows efficient capability in manipulating the direction and phase of the generated THz waves, and controlling the refractive index of Fe:In_0.53Ga_0.47As material in the THz range, in addition to enhancing the emitted THz power up to two orders of magnitude. The fast and reliable response of Fe:In_0.53Ga_0.47As to the changes in the direction and magnitude of the optical and electrical fields suggests its use in amplitude and phase modulators, and ultrafast optoelectronic systems.     

A new design for rf-excited CO2 lasers

In this paper a new ‘four-pole’ electrode design for radiofrequency excited CO₂ lasers is described. Here, the two functions of the discharge tube, rf-excitation and dischare cooling can be optimized separataly. With a symmetric rf excitation technique electromagnstic interference is also minimized. A prototype laser with 50 cm cavity length produced about 2.5 W laser output power at 5% efficiency.     

火花放电辅助下激光破坏材料的研究

分析了直流火花放电辅助下激光破坏金属和绝缘体的机理,介绍了有关实验方案和结果.研究表明,在适当的直流火花放电辅助下,激光对材料的破坏作用大大增强,这种方法可望在激光加工技术中得到有效的应用.     

直流偏置下高频磁性材料铁芯损耗的研究

对具有直流偏置、正弦电压激磁的功率铁氧体铁芯损耗进行有效测量的基础上,分析了直流偏置对铁氧体材料的性能的影响和磁损与交直流磁感应强度的关系,在一定的交流激磁范围内,为磁性元件的设计提供了一定的参考。     

荷控忆阻器记忆衰退的寄生效应

荷控忆阻器在寄生元件存在的情况下,可能发生记忆衰退现象。该文采用忆阻器动力学路线图和仿真的方法,研究了忆阻器寄生电阻和寄生电容对其动力学特性的影响。理论和仿真分析发现,理想荷控(流控)忆阻器在直流和交流激励下,寄生电阻或寄生电容单独存在时不发生记忆衰退现象,但在寄生电阻和寄生电容同时存在的情况下会发生记忆衰退,其机理是寄生元件形成放电通路,从而导致荷控忆阻器产生了记忆衰退。