Research on calibration method in lab of direct solar channels of Sun photometer

We develop a new calibration method in lab by measuring the absolute spectral irradiance responsivity of Sun photometer sun channel. The absolute power responsivity of Sun photometer is obtained when a white laser double monochromator system serve as a source, and a standard transfer detector calibrated against cryogenic absolute radiometer is assembled to measure the absolute power of laser beam. The effective area of aperture is measured through laser raster scanning method, and the relative spectral irradiance responsivity of the corresponding channel is obtained by using tungsten-halogen lamps double monoehromator system. On the basis of the above results, the top of the atmosphere responsive constants V0 （500, 675, and 870 nm） are obtained by integration with extraterrestrial solar spectral irradiance data. Comparing the calibration results with that of CIMEL, France in November 2011, the relative differences are 4.38%, 2.23%, and 2.45%, respectively. The calibration uncertainty reaches to 2.048×10^-2, which shows a remarkable consistency with the Langley plot method. Further, our scheme can overcome the limits of space and atmospheric conditions which are only available at a high-altitude calibration site in particular date. The advantages lie in not only shortening the experiment period but also being of high precision. This new scheme definitely plays an important role in supporting the current and future sun photometry calibration activities which are significant to earth observation.     

Miniature KrCl and XeBr Excimer Lamps

We propose miniature KrCl and XeBr excimer lamps based on a near-surface capacitive discharge. We show that the devices have high specific energy characteristics (radiation power density of up to 7 mW/cm²), a small emitting volume with a stable position in space, and a narrow radiation band.     

气液两相流中旋涡诱发圆柱振动时的脉动升力研究

一定条件下 ,垂直上升矩形截面管内的气液两相流横向冲刷水平布置的圆柱时 ,圆柱在与来流垂直的水平方向上受到了脉动升力的作用。本文在 1.6× 10 4到 6 .0×10 4的 Re数范围和 0到 0 .32的来流含气率范围内 ,进行了实验研究。实验中 ,流体工质为由空气和水混合而成的泡状流 ,采用弹性梁 -电阻应变式小力值传感器来测量圆柱受到的脉动升力 ,利用计算机对传感器的输出信号进行连续采集 ,采集频率为5 0 0 Hz。对由实验得到的脉动升力数据进行自功率谱分析 ,得出在两相流中只有在小于 0 .10～ 0 .12的来流含气率范围内 ,圆柱后部才会形成涡街 ,且此时的 Strouhal数随来流含气率的增大而增大 ;由脉动升力数据的均匀方根值算出脉动升力系数 C′L发现小 Re数时 C′L 随来流含气率的增大而增大 ,而在大 Re时 C′L 随来流含气率的增大先稍下降后再增大。     

三维圆柱体绕流的发展和演化

结合三阶精度格式求解可压缩NS方程，本文研究了绕过三维圆柱体的流动结构，阐明了流动的演化机理。大攻角下，在三维圆柱体背风区形成了一个脱落涡序列，其截面流态非常类似于二维圆柱绕流，主涡、二次涡以及tertiary涡形成了一个层次结构。前一个主涡脱体后，tertiary涡将演化为其后续的新生主涡，并且合并圆柱体对称面另一侧的二次涡。     

Spatial distribution of radiation intensity in sources for atomic absorption spectrometry

The spatial distribution of the intensity of radiation from LK-2 two-discharge lamps and LD-2 deuterium and halogen lamps, used in atomic absorption spectrometry, has been investigated. It is shown that the distribution of the intensity of radiation from a two-discharge lamp is saddle-shaped and is determined by the joint action of the process of cathode sputtering and of the processes of excitation and ionization of atoms of the filler element under the conditions of a high concentration of electrons in the positive column of the arc discharge. A dome-shaped distribution of radiation intensity with a maximum on the axis of the discharge is characteristic of deuterium lamps and is determined by the distribution of the concentration of electrons in the positive arc column. For halogen lamps, the intensity distribution in the form of a sharp asymmetric peak is determined by the location and dimensions of the luminescent body made in the form of a spiral. The influence of the spatial characteristics of the radiation from the sources on the error in measuring atomic absorption by a space-integrating recording system has beeb evaluated for different radiation intensity distributions. It is shown that this error is negative and reaches a maximum value for a saddle-shaped distribution of the intensity of transilluminating radiation. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 143–147, March–April, 2000.     

Karman Vortex Street in a Vibrationally Nonequilibrium Gas

The problem of vibrationally nonequilibrium gas flow past a cylinder with the formation of a Karman street is considered. The effects of relaxation on the flow parameters, namely, on vortex damping and deformation, is analyzed on the basis of a numerical simulation. A theoretical explanation of these effects is proposed.     

柱体形状对气液两相涡街的影响

本文试验研究了柱体形状对气液两相涡街的影响，得出了在气液两相流中的最佳涡街发生体和发生两相涡街时，两相斯托拉赫数，来流截面含气率，水流量三者之间的关系。试验工质为水和空气，混合物流动方向垂直向上。参数范围：相对压强０．０－０．２ＭＰａ；来流截面含气率０．０－０．３５；水流量０．０－２６ｍ３／ｈ。     

城市行道树对交通环境的影响分析

行道树作为城市绿化的"骨架",对改善城市环境具有不可估量的作用。但因为规划不合理及修剪的不科学,使得行道树侵占驾驶员视野净空、掩盖交通标志、带来交通安全隐患,对环境造成不利影响。通过合理规划绿化形式和科学修剪行道树,可以充分发挥道路绿化的功能,从而创造一个宜人、安全的交通环境。     

The degradation of poly(vinyl acetate) as a material for design objects: A multi-analytical study of the Cocoon lamps. Part 2

After the systematic study of poly(vinyl acetate) degradation presented in part 1, this work reports results from the analysis of polymeric materials from five Italian design lamps from the 1960s made of the material known as cocoon. Micro- and non-destructive molecular spectroscopic techniques have been applied directly on the object surfaces using an optical fibre probe and through examination of micro-samples: the combined use of Fourier-transform infrared spectroscopy (FTIR), pyrolysis gas-chromatography/mass-spectrometry (py-GC/MS) and Fluorescence spectroscopy allowed the assessment of the material composition and the chemical modifications of the polymers related to on-going deterioration processes. Fluorescence spectroscopy proved particularly sensitive for the detection of variations in composition among lamps and between areas on the same object, and was used to classify objects in different groups using principal component analysis of excitation emission spectra. Specific degradation products have been mapped using FTIR on micro-samples. Moreover, the interpretation of the emission spectra of the studied polymeric lamps suggests that fluorescence spectroscopy can be used for non-destructive monitoring of the degradation of historical polymeric objects.