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91.
Chih-Wei Chiang Subrata Kumar Das 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(7):1187-1195
The aerosol optical thickness (AOT) is an important parameter for understanding the radiative impact of aerosols. AOT based on lidar measurements is often limited by its finite detection range. In this paper, we have reported a method of fitting and iterative calculation to derive the extinction profile of background aerosols from 0 to 30 km at 532 nm, which is virtually the AOT of the entire atmosphere. The mean extinction derived from this method at the ground level tallies with visibility measurement and it is also consistent with the sun-photometer data, within experimental error. These data have been further treated to study the dust cases. For most of the cases, transmission losses were determined to estimate the extinction as well as lidar ratio. The result of the analysis shows that for background aerosols, a mean lidar ratio of 47±15 sr was found. For dust layers, a mean lidar ratio of 44±19 sr and an optical thickness of 0.53±0.49 were determined at 532 nm. 相似文献
92.
具有电子旋转方向的旋转间断的稳定性 总被引:1,自引:1,他引:0
用一维混合粒子编码研究了具有电子旋转方向的对称和非对称旋转间断的稳定性。发现在相对窄的过渡层厚度下,具有电子旋转方向的旋转间断是不稳定的,它趋向于发展成离子旋转方向的旋转间断和一些MHD波。这个发展过程部分地受到电子温度的限制。当过渡层厚度增加到足够宽时,电子旋转方向的旋转间断变成稳定的。本文简单地讨论了导致这种旋转间断不稳定的可能原因。 相似文献
93.
94.
本文给出了一个激光对光学材料表面热破坏效应的简化物理模型及数值研究结果。所得到的铜反射镜热破坏阈值与激光脉宽的关系与实验和理论符合很好。提出了反射镜后表面外冷却临界厚度的概念,并得到一个关于多脉冲积累效应的幂定标关系。 相似文献
95.
96.
Donata M. Fries Franz Trachsel Philipp Rudolf von Rohr 《International Journal of Multiphase Flow》2008
We used optical methods such as Laser Induced Fluorescence (LIF) and confocal Laser Scanning Microscopy (LSM) to characterize gas–liquid phase distribution in rectangular microchannels. Using a 2 m long microchannel with a hydraulic diameter of 200 μm enables the precise measurement of important parameters such as liquid slug length, bubble length, pressure drop and film thickness at the wall as well as in the corner of the microchannel for low Capillary numbers (Ca) ranging from 2 × 10−4 to 1 × 10−2. This range of Ca was obtained by using different fluid pairs such as ethanol, water and different concentrated aqueous solutions of glycerol in combination with nitrogen. 相似文献
97.
Maria F. Ebel Horst Ebel Guido Barnegg-Golwig Michael Mantler Robert Svagera 《Mikrochimica acta》1990,101(1-6):63-69
The paper gives an outline of the basic principle of our imaging technique for XPS. The advantage of the concept is its excellent applicability to quantitative pixel information. This idea is verified by two examples which are representative for routine problems in XPS. These are quantitative surface analysis and determination of overlayer thicknesses. A lateral resolution of at least 0.2 mm is achieved and thus a pixel size of 0.2 mm × 0.2 mm can be quantified automatically by means of numerical algorithms without need of reference samples.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday 相似文献
98.
An approach is proposed to solve boundary-value stress—strain problems for cylindrical shells with thickness varying in two
coordinate directions. The approach employs discrete Fourier series to separate circumferential variables. This makes it possible
to reduce the problem to a one-dimensional one, which can be solved by the stable discrete-orthogonalization method. Examples
are given
__________
Translated from Prikladnaya Mekhanika, Vol. 41, No. 6, pp. 85–94, June 2005. 相似文献
99.
Mark C. Biesinger Brad P. Payne Leo W. M. Lau Andrea Gerson Roger St. C. Smart 《Surface and interface analysis : SIA》2009,41(4):324-332
Quantitative chemical state X‐ray photoelectron spectroscopic analysis of mixed nickel metal, oxide, hydroxide and oxyhydroxide systems is challenging due to the complexity of the Ni 2p peak shapes resulting from multiplet splitting, shake‐up and plasmon loss structures. Quantification of mixed nickel chemical states and the qualitative determination of low concentrations of Ni(III) species are demonstrated via an approach based on standard spectra from quality reference samples (Ni, NiO, Ni(OH)2, NiOOH), subtraction of these spectra, and data analysis that integrates information from the Ni 2p spectrum and the O 1s spectra. Quantification of a commercial nickel powder and a thin nickel oxide film grown at 1‐Torr O2 and 300 °C for 20 min is demonstrated. The effect of uncertain relative sensitivity factors (e.g. Ni 2.67 ± 0.54) is discussed, as is the depth of measurement for thin film analysis based on calculated inelastic mean free paths. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
100.
Lamb wave sensors array for nonviscous liquid sensing 总被引:1,自引:1,他引:0
The interdigital transducer (IDT) can excite Lamb wave in a piezoelectric plate loading with a liquid layer, and the phase
velocity of Lamb wave is associated with the properties of the liquid layer. In this paper, the concept of effective permittivity
is introduced to study the Lamb wave’s potential application in liquid sensing. Considering the measuring of ideal nonviscous
liquid, the sensors array is designed to sense the density and the dielectric constant of the liquid layer simultaneously.
Using LiNbO3 as piezoelectric material, in order to improve the sensors array sensitivity and the electro-mechanical coupling coefficient,
the optimized results including plate thicknesses and cut orientations are presented by numerical simulation. These studies
show that the Lamb wave sensors array can be potential in liquid sensing. 相似文献