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991.
992.
993.
在核聚变堆的辐照环境中, 核嬗变产物氢、氦对结构材料的抗辐照性能将产生很大的影响. 本实验采用离子注入和电子辐照模拟研究了氦和氘对具有体心立方结构的纯铁的影响. 采用离子加速器在室温分别对纯铁注入氦离子和氘离子, 经500℃时效1 h后在高压电镜下进行电子辐照.结果表明: 室温注氦和室温注氘的纯铁在500℃时效后分别形成间隙型位错环和空位型位错环. 在电子辐照下, 间隙型位错环吸收间隙原子而不断长大, 而空位型位错环吸收间隙原子不断缩小. 通过计算位错环的变化速率发现, 空位型位错环比间隙型位错环吸收了更多的间隙原子, 即室温注氘纯铁的位错偏压比室温注氦纯铁的偏压参量大, 这意味着相同实验条件下空位型位错环对辐照肿胀的贡献大于间隙型位错环对辐照肿胀的贡献. 利用氦-空位复合体和氘-空位复合体的结构, 分析了注氦和注氘后在纯铁中形成不同类型位错环的原因.
关键词:
氦
氘
辐照损伤
位错环 相似文献
994.
通过对功率金属氧化物半导体场效应晶体管在静态应力下的负偏置温度不稳定性的实验研究, 发现器件参数的退化随时间的关系遵循反应扩散模型所描述的幂函数关系, 并且在不同栅压应力下, 实验结果中均可观察到平台阶段的出现. 基于反应扩散理论的模型进行了仿真研究, 通过仿真结果分析和验证了此平台阶段对应于反应平衡阶段, 并且解释了栅压应力导致平台阶段持续时间不同的原因.
关键词:
功率金属氧化物半导体场效应晶体管
负偏置温度不稳定性
反应扩散模型 相似文献
995.
为得出Buck变换器的输出本质安全判据, 基于安全火花试验装置, 对其输出短路火花放电特性进行了试验研究, 发现其放电过程可分为介质击穿、火花产生、火花维持和火花熄灭四个阶段.基于得出的火花放电特性, 对其输出短路火花放电能量进行了深入分析, 指出对于给定电感的Buck变换器, 当负载电阻 RL小于给定电感对应的临界电阻RLC时, 火花放电能量是关于RL的凹函数; 而在RL > RLC时, 是关于RL的凸函数.考虑到实际的参数取值范围, 进一步指出: RL < RLC时的火花放电能量随RL的增加而增大, 且在RL=RLC时达到最大值; 而在RL > RLC时, 则随着RL的增加, 先增大后减小, 在增加到特征电阻RL, DCM时达到最大值. 得出了变换器在全动态范围内的最危险工况: 变换器在输入电压最高及负载电阻等于RL, DCM 时工作于DCM, 此时, 短路火花放电能量达到最大值.基于能量等效, 提出了可模拟变换器输出短路放电特性的等效简单电容电路及输出本质安全判据, 仿真和试验结果验证了理论分析及所提出判据的正确性和可行性.
关键词:
Buck变换器
本质安全
短路火花放电能量
输出本质安全判据 相似文献
996.
Naoya Tate Makoto Naruse Yang Liu Tadashi Kawazoe Takashi Yatsui Motoichi Ohtsu 《Applied physics. B, Lasers and optics》2013,112(4):587-592
We have previously demonstrated a novel technique for autonomously forming a nanophotonic droplet, which is micro-scale spherical polymer structure that contains paired heterogeneous nanometric components. The sort-selectivity and alignment accuracy of the nanometric components in each nanophotonic droplet, and the related homogeneity of the optical function, are due to a characteristic pairing process based on a phonon-assisted photo-curing method. The proposed method requires irradiating a mixture of components with light to induce optical near-field interactions between each component, and subsequent processes based on these interactions. The pairing yield of components via the interactions is considered to mainly depend on the frequency of their encounters and the size-resonance effect between encountered components. In this paper, we model these two factors by individual stochastic procedures and construct a numerical model to describe the pairing process. Agreement between the results of numerical and experimental demonstrations shows the validity of our stochastic modeling. 相似文献
997.
A new Fiber Bragg Grating (FBG) wavelength demodulation scheme is studied in the paper, which consists of an improved de-noising method and Gaussian fitting peak searching algorithm. The improved translational invariant wavelet without threshold adjust factor is proposed to get a better de-noising performance for FBG sensor signal and overcome the drawbacks of soft or hard threshold wavelets. In order to get a high wavelength demodulation precision of FBG sensor signal, this de-noising method is designed to combine with Gaussian fitting peak searching algorithm. The simulation results show that the wavelength maximum measurement error is lower than 1 pm, and can get a much higher accuracy. 相似文献
998.
Bidirectional ellipsometry has been developed as a technique for distinguishing among various scattering features near surfaces. The polarized angular dependence of three-dimensional light-scattering by the nanoparticles on thin film wafer is calculated and measured. These calculations and measurements yield angular dependence of bidirectional ellipsometric parameters for out-of-plane light-scattering. The experimental data show good agreement with theoretical predictions for different nanoparticle diameters and thin film thicknesses when bidirectional ellipsometry was employed to measure nanoparticles (60 nm, 100 nm, and 200 nm) on Si wafers with different film thicknesses of 2 nm, 5 nm, and 10 nm. Not only are the diameters of the nanoparticles determined, but also the film thicknesses can be calculated and distinguished from the measurement results. Additionally, the results indicate that improved accuracy is possible for measurements of scattering features from nanoparticles and thin films. 相似文献
999.
A new three-dimensional chaotic system with large scope of parameters is proposed. Its properties such as equilibrium points, Poincaré map, the largest Lyapunov exponent spectra and bifurcation diagrams are analyzed theoretically and numerically. Theoretical analyses and simulation tests indicate that the proposed chaotic system can keep chaotic in a wide range of parameters. The system is recommendable for many engineering applications such as secure communications, cryptology, information processing, etc. 相似文献
1000.
With the development of airborne and spaceborne remote sensing from the 1980s, as a new and growing technology, hyperspectral imaging is widely used in different fields, such as military investigation, battlefield information acquisition, environmental monitoring, mineral exploration and public security. Because of the unique characteristic of acquiring spectral and spatial information simultaneously, it brings the hyperspectral detection advantages when dealing with target detection problem under complex conditions. Target detecting models of hyperspectral image are established, including the target subspace model and the probability statistical model. And several algorithms are introduced, which are based on original spectral features, sub-space projection and probability statistical model separately. Comparison shows that if the background includes fault objectives, GLRT is the best algorithm, and its SINR is the largest; on condition of anomaly target detection, LPTD is the best, and have a quite high SINR. 相似文献