CONVERSION RATES OF SURFACE HOX RADICALS IN BEIJING CITY     

REN Xin-rong    WANG Li-xin  WANG Hui-xiang  MIAO Guo-fang 《中国地理科学(英文版)》2004,14(1):34-38

1INTRODUCTIONThe hydroxyl radicals play a central role in atmospher-ic photochemistry, reacting with a lot of compounds, often initiating their oxidation and subsequent loss and resulting in the formation of ozone and other deleteri-ous oxidants, acids, and fine particles in polluted ar-eas. A thorough understanding of this role is necessary for efficient, cost-effective pollution control. There-fore, the measurement of OH is very significant (E-HHAT etal., 1991). Nevertheless, most me…  相似文献   

Scope of high-frequency time keeping in searches for short-period gamma-ray sources     

M. L. Sapru  A. K. Tickoo  I. K. Kaul  S. K. Kaul  C. L. Bhat  R. K. Kaul  H. S. Rawat  V. K. Senecha  R. C. Rannot  H. Razdan 《Journal of Astrophysics and Astronomy》1990,11(2):141-150

This paper presents a novel technique to derive the absolute time of occurrence of an event with an accuracy of < 200 μs by adapting the HF time synchronization technique to correct for the aging rate and the frequency drift of a temperature-controlled quartz frequency standard. The propagation delay suffered by the HF time signals has been estimated by monitoring the clock error with respect to time signals from five broadcast stations located at distances in the range 500–3700 km from Gulmarg. Using simulated data, we further show the viability of this technique in permitting periodicity searches on timescales of ≥5 milliseconds in cosmic gamma-ray data An erratum to this article is available at .  相似文献   

INFLUENCE OF SEA－AIR INTERACTION ON THEDISCHARGE OF FLOOD SEASON IN THEUPPER REACHES OF THE CHANGJIANG RIVER     

章新平  范钟秀  周恩济 《中国地理科学(英文版)》1994,4(1):31-42

ＩＮＦＬＵＥＮＣＥＯＦＳＥＡ－ＡＩＲＩＮＴＥＲＡＣＴＩＯＮＯＮＴＨＥＤＩＳＣＨＡＲＧＥＯＦＦＬＯＯＤＳＥＡＳＯＮＩＮＴＨＥＵＰＰＥＲＲＥＡＣＨＥＳＯＦＴＨＥＣＨＡＮＧＪＩＡＮＧＲＩＶＥＲＺｈａｎｇＸｉｎｐｉｎｇ（章新平）（ＬａｎｚｈｏｕＩｎｓｔｉｔｕ...  相似文献   

作为随机振动的海冰变化模型     

蒋维东 《成都信息工程学院学报》1990,(Z1)

本文从B.Saltzman的海温—海冰模式出发,得到了一个描述海冰范围变化的随机气候模型,接着对模型的性质进行了一些分析和讨论,并把从模型得到的模拟谱与计算的南极海冰扩展范围的观测谱做了比较。  相似文献   

Image Field Deformation of LAMOST due to Differential Atmospheric Refraction     

Jin-Ling Li  Bo Zhang  Yong Yu  Zhao-Xiang Qi  Ming Zhao Shanghai Astronomical Observatory  Chinese Academy of Sciences  Shanghai   《中国天文和天体物理学报》2006,6(4):495-502

A vectorial expression of the image field deformation of LAMOST due to the differential atmospheric refraction is presented. The calculated results are compared with those from previous analyses based on the traditional spherical trigonometric formulas. It is demonstrated that different tangential displacements of star images during the observation tracking given by various authors are simply due to different reference points adopted. It is pointed out that the observational celestial pole is the center of the apparent diurnal motion, that, by referring to the observational celestial pole, the effect of the differential refraction on the image field of LAMOST during the 1.5-hour tracking period is approximately equivalent to a constant rotation of -13.65" for all declination belts. It is therefore unnecessary to design a particular tracking velocity for each observation, and this will be obviously advantageous to the observation implementation. If the maximum tracking error of the fibers is 0.2", then the fibers are required to be able to re-position during observational tracking for sky regions south of declination 20°and north of declination 60°.  相似文献   

月球激光测距的新技术方法研究     

熊耀恒 《天文研究与技术》2002,(1)

月球激光测距是国内外所瞩目的宏伟目标 ,代表着单光子探测技术的高峰。本论文的目的是探索提高激光测月回波光子数的新方法 ,进而增加激光测月成功的几率。其思路是源于一个新的想法 :在激光测月过程中引入大气波前倾斜量实时补偿的技术。首先介绍激光测月的现状和其难度所在 :回波光子数太少 ,基本上属于亚光子探测范畴。在现有技术条件下 ,本文对影响激光测月回波光子数的因素逐一进行分析讨论 ,提出应该把激光束截面能量分布和大气湍流效应包括进去。为此分析讨论了大气湍流和大气中光场的基本统计性质、激光束在大气中传输时所受大气湍流的影响以及大气湍流对激光测距的影响 ,得出大气湍流特别对激光测月有着明显影响的结论。在此基础上对传统的激光测距方程进行了修正 ,使其应用到激光测月时更符合真实的情况 ,从而指导补偿的进行。涉及到在激光测月中对受大气湍流而畸变的激光束进行补偿 ,本文抓住重点 ,通过分析看出对大气倾斜量的实时补偿是提高激光测月回波光子数的重要因素。结合激光测月以及云南天文台现有测距系统的实际情况 ,本文独创性地提出利用激光测月目标近旁一定大小区域的扩展面源探测与计算大气倾斜量 ,然后对激光测月中的激光束进行大气倾斜量实时补偿的新技术方法。在分析比较  相似文献   

The optical reflector system for the CANGAROO-II imaging atmospheric Cherenkov telescope     

A. Kawachi  Y. Hayami  J. Jimbo  S. Kamei  T. Kifune  H. Kubo  J. Kushida  S. LeBohec  K. Miyawaki  M. Mori  K. Nishijima  J. R. Patterson  R. Suzuki  T. Tanimori  S. Yanagita  T. Yoshikoshi  A. Yuki 《Astroparticle Physics》2001,14(4):1492-269

A new imaging atmospheric Cherenkov telescope with a light-weight reflector has been constructed. Light, robust, and durable mirror facets of containing carbon fiber reinforced plastic laminates were developed for the telescope. The reflector has a parabolic shape (f/1.1) with a 30 m² surface area, which consists of 60 spherical mirror facets. The image size of each mirror facet is 0°.08 (FWHM) on average. The attitude of each facet can be adjusted by stepping motors. After the first in situ adjustment, a point image of about 0°.14 (FWHM) over 3° field of view was obtained. The effect of gravitational load on the optical system was confirmed to be negligible at the focal plane. The telescope has been in operation with an energy threshold for γ-rays of 300 GeV since May 1999.  相似文献   

我国天文台及潜在台址所在地区Fried参数γ0的计算与统计分析     

李双喜  傅元芬  黄寅亮  李建国  毛节泰 《天文学报》2002,43(1):106-110

用1986-1995年的10年探空气象资料，在塔塔尔斯基模式下，计算了我国天语言台及候选台址所在的10个地区的Fried参数r0。给出了地面、900米、1500米、3000米、5000米各度上的r0年平均值。在3000米高度上冬季丽江视宁度最好，夏季酒泉最好，均达到相应季节定日4301米高度上视宁度水平。  相似文献   

自适应光学技术应用于激光测月中大气波前倾斜量的探测与计算   总被引：2，自引：0，他引：2  

郭锐  熊耀恒 《天文学报》2004,45(4):413-421

针对云南天文台1.2米望远镜在激光测月中回波光子数太少的问题，将大气湍流效应考虑到激光测月中，研究了互相关和绝对差分两种跟踪算法的原理，并编写了算法程序，利用太阳数据验证了程序的正确性,给出了根据所采集的月面感兴趣区域的图像数据，用不同方法在不同条件下处理所得的大气波前整体倾斜信号，比较了算法的优劣。  相似文献   

MSISE90大气密度模型及其在GPS无线电掩星中的应用     

蒋虎  黄珹 《天文研究与技术》2001,(2):26-30

本文简略介绍了MSISE90大气密度模型，它是以提高低高度大气密度计算精度为目标，基于MSIS86模式，采用不相干散射雷达和卫星质谱仪测量资料，在半经验公式的基础上进行拟合处理而成；并指出了Hedin对该模型的修正之处。并将该模型应用于GPS无线电掩星反演中性地球大气参数的先验温度序列的生成。  相似文献