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101.
Marcel Carbillet Philippe Bendjoya Lyu Abe G��raldine Guerri Anthony Boccaletti Jean-Baptiste Daban Kjetil Dohlen Andr�� Ferrari Sylvie Robbe-Dubois Richard Douet Farrokh Vakili 《Experimental Astronomy》2011,30(1):39-58
SPHERE (which stands for Spectro-Polarimetric High-contrast Exoplanet REsearch) is a second-generation Very Large Telescope (VLT) instrument dedicated to high-contrast direct imaging of exoplanets which first-light is scheduled for 2011. Within this complex instrument one of the central components is the apodized Lyot coronagraph (ALC). The present paper reports on the most interesting aspects and results of the whole numerical study made during the design of the ALC for SPHERE/VLT. The method followed for this study is purely numerical, but with an end-to-end approach which is largely fed by a number of instrumental feedbacks. The results obtained and presented in this paper firstly permit to finalize the optical design before laboratory performance testing of the ALC being built for SPHERE/VLT (see paper II ??Laboratory tests and performances??), but will also hopefully help conceiving future other instruments alike, for example within the very promising extremely large telescope perspective. 相似文献
102.
根据我国海洋综合气象监测装备建设网点不继扩大和加密的现状,依靠现有的卫星通信网络,利用其覆盖范围广、通信稳定、实时在线和维持经费等优势,设计一种基于卫星通信网络的海洋气象数据采集系统.介绍该系统的数据采集结构和功能,智能处理终端的硬件组成,硬件电路芯片选型与使用;介绍系统软件的控制和编制方法,简述在可视化编程语言Microsoft Visual Studi0 6.0集成包环境下开发海洋气象数据采集系统软件的步骤;讨论基于我国北斗卫星通信网络的海洋气象数据采集系统的实际应用情况. 相似文献
103.
利用NCEP1°×1°再分析资料,对2015年7月西太平洋洋面上台风"莲花""灿鸿""浪卡"三者共存期间的路径特征、强度变化及相互作用进行了分析。结果表明:1)台风"莲花"与"灿鸿"发生互旋,导致强度较弱的"莲花"路径发生逆时针转向;"灿鸿"与"浪卡"发生明显的相互作用。2)"莲花"的低层水汽通道在互旋过程中被"灿鸿"夺走,后者产生反馈气流补充前者;"浪卡"与"灿鸿"在对流层高层通过水汽"连体"通道进行水汽交换。3)与"莲花"互旋过程中"灿鸿"产生的反馈气流远比相互作用过程中"浪卡"对"灿鸿"的补充气流强,因此相互作用过程结束后"莲花"暖心与涡度继续维持,而"灿鸿"迅速衰弱。4)两个台风相互作用过程的水汽"连体"通道高度不同,台风"莲花"与"灿鸿"相互作用位于对流层低层,而台风"灿鸿"与"浪卡"相互作用发生在对流层高层。 相似文献
104.
基于标准化降水蒸散指数(SPEI),利用淮北地区108个气象站逐月气温、降水观测资料,采用线性趋势、M K突变检验等方法,从不同时间尺度(年、季)和干旱程度(轻旱、中旱、重旱和特旱)分析了淮北地区1961—2015年干旱频率和时空变化特征。结果表明:淮北地区1961—2015年总体呈干旱略加强趋势,其中1998—2001年干旱发生最频繁,干旱强度、极端干旱及中等干旱的频次均呈增加趋势。2011年淮北地区干旱程度发生了突变性增强;20世纪90年代起淮北地区夏季经历了先湿后干的转变,2013年是夏季转向干旱化的突变点。秋冬两季是淮北地区发生干旱频率较高的季节。秋季干旱分布广、旱情最为严重,淮北地区北部是秋季干旱的高发区;冬季发生中旱以上干旱的地区分布较广,主要位于淮北地区内的安徽片西部和江苏片中部。春夏季发生高频率干旱的区域相对较小。 相似文献
105.
�������ֽ�ؿ��˶������о� 总被引:2,自引:1,他引:1
????1998??2009?????GPS?????????о???????壨18.5??25.5??104.5??112.0????ITRF2000????μ??????????????????????ο?????μ?????α????????????????????????????о????滪???????NE115?????????????????????33.5 mm/a?????????????3.5 mm/a?????????????????? 相似文献
106.
The prediction accuracy of the traditional stepwise regression prediction equation (SRPE) is affected by the multicollinearity among its predictors.This paper introduces the condition number analysis into the prediction modeling to minimize the multicollinearity in the SRPE.In the condition number prediction modeling,the condition number is used to select the combination of predictors with the lowest multicollinearity from the possible combinations of a number of candidate predictors (variables),and the sel... 相似文献
107.
I. P. Chunchuzov V. G. Perepelkin S. N. Kulichkov G. I. Gorchakov M. A. Kallistratova A. V. Dzhola J. Lyu P. Teng Y. Yang W. Lin Q. Li Y. Sun 《Izvestiya Atmospheric and Oceanic Physics》2017,53(5):524-538
The influence of internal gravity waves on the spatial coherence and temporal variability of the atmospheric pressure, wind velocity, and gas constituents near Moscow and Beijing is studied in the mesoscale range of periods: from a few tens of seconds to several hours. The results of simultaneous measurements of variations in the atmospheric pressure (using a network of spaced microbarographs), wind velocity at different heights of the atmospheric boundary layer, and gas constituents are given for each city. The wave structures are filtered using a coherence analysis of the atmospheric pressure variations at different measurement sites. The dominant periods and the coherences, phase speeds, and horizontal scales of variations corresponding to these periods are estimated. The general mechanism of the influence of wave structures on meteorological fields and gas constituents is discussed, which is independent of the measurement site and the specificity of meteorological conditions. 相似文献
108.
Rising sea levels threaten the sustainability of coastal wetlands around the globe. The ability of coastal marshes to maintain their position in the intertidal zone depends on the accumulation of both organic and inorganic materials, and vegetation is important in these processes. To study the effects of vegetation type on surface elevation change, we measured surface accretion and elevation change from 2011 to 2016 using rod surface elevation table and feldspar marker horizon method(RSET-MH) in two Phragmites and two Suaeda marshes in the Liaohe River Delta. The Phragmites marshes exhibited higher rates of surface accretion and elevation change than the Suaeda marshes. The two Phragmites marsh sites had average surface elevation change rates at 8.78 mm/yr and 9.26 mm/yr and surface accretion rates at 17.56 mm/yr and 17.88 mm/yr, respectively. At the same time, the two Suaeda marsh sites had average surface elevation change rates at 5.77 mm/yr and 5.91 mm/yr and surface accretion rates at 13.42 mm/yr and 14.38 mm/yr, respectively. The elevation change rates in both the Phragmites marshes and the Suaeda marshes in the Liaohe River Delta could keep pace and even continue to gain elevation relative to averaged sea level rise in the Bohai Sea reported by the 2016 State Oceanic Administration, People's Republic of China projection(2.4–5.5 mm/yr) in current situations. Our data suggest that vegetation is important in the accretionary processes and vegetation type could regulate the wetland surface elevation. However, the vulnerability of coastal wetlands in the Liaohe River Delta need further assessment considering the accelerated sea level rise, the high rate of subsidence, and the declining sediment delivery, especially for the Suaeda marshes. 相似文献
109.
Soil freeze-thaw process is closely related to surface energy budget,hydrological activity,and terrestrial ecosystems.In this study,two numerical experiments(including and excluding soil freeze-thaw process)were designed to examine the effect of soil freeze-thaw process on surface hydrologic and thermal fluxes in frozen ground region in the Northern Hemisphere based on the state-of-the-art Community Earth System Model version 1.0.5.Results show that in response to soil freeze-thaw process,the area averaged soil temperature in the shallow layer(0.0175?0.0451 m)decreases by 0.35℃in the TP(Tibetan Plateau),0.69℃in CES(Central and Eastern Siberia),and 0.6℃in NA(North America)during summer,and increases by 1.93℃in the TP,2.28℃in CES and 1.61℃in NA during winter,respectively.Meanwhile,in response to soil freeze-thaw process,the area averaged soil liquid water content increases in summer and decrease in winter.For surface heat flux components,the ground heat flux is most significantly affected by the freeze-thaw process in both summer and winter,followed by sensible heat flux and latent heat flux in summer.In the TP area,the ground heat flux increases by 2.82 W/m2(28.5%)in summer and decreases by 3.63 W/m2(40%)in winter.Meanwhile,in CES,the ground heat flux increases by 1.89 W/m2(11.3%)in summer and decreases by 1.41 W/m2(18.6%)in winter.The heat fluxes in the Tibetan Plateau are more susceptible to the freeze-thaw process compared with the high-latitude frozen soil regions.Soil freeze-thaw process can induce significant warming in the Tibetan Plateau in winter.Also,this process induces significant cooling in high-latitude regions in summer.The frozen ground can prevent soil liquid water from infiltrating to deep soil layers at the beginning of thawing;however,as the frozen ground thaws continuously,the infiltration of the liquid water increases and the deep soil can store water like a sponge,accompanied by decreasing surface runoff.The influence of the soil freeze-thaw process on surface hydrologic and thermal fluxes varies seasonally and spatially. 相似文献
110.
变形石墨对构造- 热过程的定量约束及流变弱化意义 总被引:1,自引:0,他引:1
岩石变形过程的精细厘定是构造地质学研究中的难点和重点。石墨是碳的同素异形体,摩擦实验研究表明,增加少量石墨化碳质物能够显著降低岩石的摩擦系数和力学强度,具有固体润滑剂的流变学意义。本研究针对红河- 哀牢山剪切带新生代变形,开展了详细的野外观测和构造解析,针对不同变形- 变质程度的天然含石墨岩石样品,利用光学显微镜、场发射扫描电子显微镜、电子背散射衍射(EBSD)、拉曼光谱方法,开展了详细的显微及亚显微变质与变形构造、矿物晶格优选定向、石墨拉曼地质温度计应用等深入分析。发现深变质岩中,石墨晶体常常与黑云母共生且定向拉伸或生长,呈现出晶质片状、条带状、膝折等变形构造特征;在强烈塑性变形的岩石中,石墨表现出塑性到超塑性流动构造特征;细粒化石墨富集形成微型滑移带/面,承载流变弱化的“干”润滑作用;在低级变质- 弱变形岩石中,石墨有序度低,呈弥散状分布。EBSD组构显示石墨发育柱面、菱面到低温底面晶格滑移系,对应的石墨拉曼地质温度范围为600~500℃、530~460℃、450~400℃。变形石墨的位错滑移系具有与石英位错滑移系类似的演化特征,具有成为变形温度计的潜力。 相似文献