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排序方式: 共有169条查询结果,搜索用时 78 毫秒
161.
为满足高能激光从谐振腔真空室到大气环境的输出要求,减小窗口热变形对输出激光束性能的影响,提出了一种通过旋转固体窗口降低其受辐照功率密度的解决方案。该方案通过大力矩空心直流电机带动固体窗口匀速转动,并采用高精度动密封圈隔离真空和大气,使得强激光对CaF2窗口的辐照均匀化,从而大大减小CaF2窗口的温度梯度和应力,极大改善了输出光束性能,并有效避免了长时间出光时CaF2窗口炸裂现象的发生。研究结果表明:该方案具有体积小、重量轻、结构紧凑、使用方便和性能可靠等优点,可有效改善激光器输出光束质量,使高能激光长时间输出成为可能。 相似文献
163.
Damien Larroumet David Greenfield Robert Akid Jack Yarwood 《Journal of Raman spectroscopy : JRS》2008,39(12):1740-1748
We have extended our unenhanced (non-SERS) Raman spectroscopic investigations to include a study of the corrosion of an iron electrode in carbonate and phosphate buffer solutions. The measurements have been supported by electrochemical investigations (via cyclic voltammetry), enabling oxidation and reduction reactions to be systematically followed at variable applied potentials. In a carbonate buffer (pH = 9.4) the surface oxidation led to the formation of a ‘green rust’ (a hydrated hydroxy-carbonate), followed by the α- and β-forms of FeOOH and an underlying magnetite layer formed on the cathodic (reduction) cycle. In a phosphate buffer (pH = 7.7) the surface was passivated by hydrated phosphates of iron [identified as FePO4 · xH2O and Fe3(PO4)2·8H2O]. The formation of oxides (Fe2O3 and Fe3O4) were inferred from voltammetry, but spectral identification was more difficult because of broad, ill-defined spectra. Despite the challenges of using unenhanced Raman spectroscopy, we believe that the effort was worthwhile, the reactions identified being more likely to be relevant to real electrochemical environments. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
164.
We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions to the running of the QED coupling,αh(5a)d(MZ2).Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV. 相似文献
165.
Liquid crystal thermography and pressure drop measurements have been carried out to study the heat transfer and frictional characteristics in a rectangular duct with solid ribs (C1), converging slit-ribs (C2), and alternate solid-slit ribs (C3) mounted transversely on the bottom wall, where C2 carries a continuous converging-slit in the flow direction. Effect of rib configurations, and rib pitch to height ratios (6, 8, 10, and 12) has been investigated at Re of 9400, 26160, 42500, and 58850. Results show that converging-slit considerably enhances the heat transfer rate in the downstream vicinity, and help in obviating the local hot spot formation.
Abbreviations: LCT: Liquid crystal thermography; HTC: Heat transfer coefficient; LHI: Laser holographic interferometry; NST: Naphthalene sublimation technique; IR: Infrared; TPF: Thermo-hydraulic performance; PIV: Particle image velocimetry. 相似文献
166.
基于三维荧光光谱结合小波压缩与交替惩罚三线性分解(APTLD)对水中多环芳烃(PAHs)进行定性和定量分析,实验以萘(NAP)、芴(FLU)、苊(ANA)为测量样品。首先用FS920荧光光谱仪测量获得样品的三维荧光光谱数据,对数据进行激发和发射校正且去散射,得到真实光谱。为了解决三维荧光光谱数据的冗余信息,通过小波变换对实验光谱数据进行压缩,其压缩分数和数据恢复分数分别大于92%和95%。用APTLD对压缩后的光谱数据进行分析,体现了二阶优势,实验结果表明,在PAHs的荧光光谱严重重叠和有干扰物共存下,该方法仍能准确地测定,其回收率为94%~98%、预测均方根误差小于0.29 μg·L-1。 相似文献
167.
为满足高能激光从谐振腔真空室到大气环境的输出要求,减小窗口热变形对输出激光束性能的影响,提出了一种通过旋转固体窗口降低其受辐照功率密度的解决方案。该方案通过大力矩空心直流电机带动固体窗口匀速转动,并采用高精度动密封圈隔离真空和大气,使得强激光对CaF2窗口的辐照均匀化,从而大大减小CaF2窗口的温度梯度和应力,极大改善了输出光束性能,并有效避免了长时间出光时CaF2窗口炸裂现象的发生。研究结果表明:该方案具有体积小、重量轻、结构紧凑、使用方便和性能可靠等优点,可有效改善激光器输出光束质量,使高能激光长时间输出成为可能。 相似文献
168.
The reversible isomerism of indolinospirobenzopyrans is perhaps among the most studied phenomena in the field of molecular switches. Although they began to gain attention as early as 70 years ago following the seminal work of Hirshberg and Fischer, who were the first to recognize their photochromic behaviours, their implementation as photoacids emerged prominently only in the last decade. In this Review, we contextualize the prerequisites underlying the photo-triggered proton release that occurs in these molecular switches, highlighting the most recent advances in their characterization and application as “metastable-state photoacids” in water. 相似文献
169.
《Indagationes Mathematicae》2023,34(5):1121-1145
In this paper we consider the notions of binomial thinning, binomial mixing, their generalizations, certain interplay between them, associated limit theorems and provide various examples. 相似文献