排序方式: 共有86条查询结果,搜索用时 15 毫秒
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提出了基于M?llenstedt电子双棱镜的电压扫描剪切干涉全场ptychographic iterative engine(PIE)显微成像技术.从低到高逐步改变电子双棱镜的电压,并同时记录所形成的剪切干涉条纹,待测样品透射电子束的强度和相位分布就可以用PIE算法得以快速重建,而且双棱镜的方向、位置和实际电场强度分布等诸多实验中不可避免地偏差都可以在迭代过程中自动得以更正.所提技术能够克服现阶段用电子束进行PIE成像的诸多技术困扰,从而有望推动PIE技术在电子显微成像领域的发展和应用. 相似文献
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采用加权函数修正的差分光学吸收光谱技术(weighting function modified differential optical absorption spectroscopy, WFM-DOAS)测量环境大气中的CO2垂直柱浓度. 以直射太阳光测量光谱为例, 演示了WFM-DOAS算法的实现过程. 将环境大气分为50层, 借助辐射传输模拟软件SCIATRAN对各个测量光谱进行了模拟计算, 获得了最小二乘法拟合所需的目标气体CO2及干扰气体H2O、CH4 的柱权重函数和太阳归一化光谱常量. 采用WFM-DOAS方法对一整天的直射太阳光测量光谱进行了反演, 得到的反演误差均小于3%. 最后比较了两种不同DOAS算法对同一条测量光谱的反演结果, 验证了WFM-DOAS算法在红外被动气体遥感的优越性.
关键词:
环境污染监测
光学测量技术
红外光谱
温室气体 相似文献
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差分吸收光谱技术监测气溶胶光学厚度及大气能见度的研究 总被引:5,自引:4,他引:1
介绍了一种基于闪烁氙灯光源、利用差分光谱吸收(DOAS)技术监测大气气溶胶的新方法。提出用大气能见度确定系统校正参量的可行做法,解决了差分光谱吸收探测气溶胶领域原始光强难以测量的难题。并对350~650 nm范围内的气溶胶光学厚度进行反演,通过与多道太阳光度计的对比证实方法的可行性,实验中发现气溶胶光学厚度与悬浮颗粒物(SPM)浓度具有很好的相关性。同时,利用气溶胶550 nm处的消光系数确定大气能见度。 相似文献
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Recently,a novel four-dimensional Einstein-Gauss-Bonnet(4 EGB) theory of gravity was proposed by Glavan and Lin [D.Glavan and C.Lin,Phys.Rev.Lett.124,081301(2020)],which includes a regularized GaussBonnet term using the re-scalaring of the Gauss-Bonnet coupling constant α→α/(D-4) in the limit D→4.This theory has also been reformulated to a specific class of the Homdeski theory with an additional scalar degree of freedom and to a spatial covariant version with a Lagrangian multiplier,which can eliminate the scalar mode.Here,we study the physical properties of the electromagnetic radiation emitted from a thin accretion disk around a static spherically symmetric black hole in 4 EGB gravity.For this purpose,we assume the disk is in a steady-state and in hydrodynamic and thermodynamic equilibrium,so that the emitted electromagnetic radiation is a black body spectrum.We study in detail the effects of the Gauss-Bonnet coupling constant α in 4 EGB gravity on the energy flux,temperature distribution,and electromagnetic spectrum of the disk.With an increase in the parameter α,the energy flux,temperature distribution,and electromagnetic spectrum of the accretion disk all increase.We also show that the accretion efficiency increases with the growth of the parameter α.Our results indicate that the thin accretion disk around a static spherically symmetric black hole in 4 EGB gravity is hotter,more luminous,and more efficient than that around a Schwarzschild black hole with the same mass for positive α,while it is cooler,less luminous,and less efficient for negative α. 相似文献
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The transonic phenomenon of black hole accretion and the existence of the photon sphere characterize strong gravitational fields near a black hole horizon.Here,we study the spherical accretion flow onto general parametrized spherically symmetric black hole spacetimes.We analyze the accretion process for various perfect fluids,such as the isothermal fluids of ultra-stiff,ultra-relativistic,and sub-relativistic types,and the polytropic fluid.The influences of additional parameters,beyond the Schwarzschild black hole in the framework of general parameterized spherically symmetric black holes,on the flow behavior of the above-mentioned test fluids are studied in detail.In addition,by studying the accretion of the ideal photon gas,we further discuss the correspondence between the sonic radius of the accreting photon gas and the photon sphere for general parameterized spherically symmetric black holes.Possible extensions of our analysis are also discussed. 相似文献
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采用Mitsunobu反应将杂环偶氮生色分子键入氟化聚酰亚胺母体制备新型的侧链含氟聚酰亚胺非线性光学(NLO)材料.采用傅里叶变换红外(FT-IR)光谱、紫外-可见(UV-Vis)光谱、1H核磁共振(1HNMR)谱和凝胶色谱(GPC)对材料进行表征.热分析结果表明侧链型聚酰亚胺具有较高的玻璃化转变温度(Tg)(184-188℃),热分解温度(Td)高达322℃.采用简单全反射法于1550nm处测定聚酰亚胺的电光系数(γ33),含苯并噻唑偶氮苯胺的聚酰亚胺(PI1)具有较高的电光系数15pm·V-1. 相似文献