中国首颗综合性太阳探测卫星          下载免费PDF全文

甘为群  诸成  陈斌  黄宇 《天文学报》2022,63(6):60

作为中国首颗综合性太阳探测卫星的先进天基太阳天文台(Advanced Space-based Solar Observatory, ASO-S)于北京时间2022年10月9日7时43分在酒泉卫星发射中心成功发射. 扼要介绍ASO-S卫星提出的背景、卫星的研制历程、科学目标、载荷构成、任务总体以及卫星研制的组织架构, 并对卫星的运行和科学产出略作展望.  相似文献   

新疆地下流体源兆、场兆、大震远兆特征的统计与分析   总被引：7，自引：0，他引：7  

高小其  陈华静  高国英  许秋龙  崔勇 《地震》2006,26(2):83-94

以20多年来新疆地区的18个地下流体监测点的资料为基础, 沿着“异常与震中”这一主线, 对新疆地区的16次5级地震、 4次 7级以上地震及1个6级强震群的前兆异常特征进行了定量的统计与分析。 结果表明, 源、 场、 远兆异常有如下特征: 异常空间展布不均, 源兆空间内异常监测点展布"密集"、 异常比例可达90%; 而场兆空间展布“稀疏”、 “分散”, 异常比例一般在45%～53%; 而远兆则是更加“稀疏”和“零星”, 异常比例统计为25%。 异常起始时间不同, 源兆异常时间以中期为主; 中强震场兆异常时间以中短期、 特别是短期为主; 强震场兆以中期异常为主; 而强震远兆则也以中期异常为主。 异常形态不同, 源兆中期异常及强震场兆中期异常一般是趋势性大幅度升高变化为主, 且以化学测项为多, 油气探井以井喷形式予以表现; 而中强震场兆异常, 一般表现为幅度明显的短期内的负异常、 脉冲突跳、 短期内的高值上升、 阶变及年变化规律被打破等; 强震远兆特征则基本上表现为少数测点、 测项的大幅度中期异常及个别测项的临震大幅度突跳现象, 油气探井则也以剧烈井喷形式予以表现。  相似文献   

Effects of wave age and air stability on whitecap coverage     

Dag Myrhaug  Lars Erik Holmedal 《Coastal Engineering》2008,55(12):959-966

The paper considers the effects of wave age and air stability on the whitecap coverage at sea. This is made by using the logarithmic mean wind velocity profile including a stability function as well as adopting a recent wave age dependent sea surface roughness formula. The results are valid for wind waves in local equilibrium with the steady wind. Examples of results demonstrate clear effects of wave age and air stability on the whitecap coverage. Comparisons are also made with field measurements by Sugihara et al. [Sugihara, Y., et al., 2007. Variation of whitecap coverage with wave-field conditions. J. Mar. Syst. 66, 47–60], representing unstable air stability conditions. Although the data basis is limited, the wave age independent Charnock sea roughness based predictions capture the main features of the observed whitecap coverage, suggesting a stronger dependence on air stability than on wave age in the data.  相似文献   

Evolution of provenance in the NE Atlantic rift: The Early–Middle Jurassic succession in the Heidrun Field,Halten Terrace,offshore Mid-Norway     

Andrew Morton  Claire Hallsworth  Dominic Strogen  Andrew Whitham  Mark Fanning 《Marine and Petroleum Geology》2009

An integrated provenance study using provenance-sensitive heavy mineral ratios, mineral chemistry and U/Pb dating of detrital zircons has revealed significant changes in sediment provenance during deposition of the Early to Middle Jurassic succession in the Heidrun Field, offshore Mid-Norway. The variations result from the interplay of two source regions, one of which was located on the Norwegian landmass and the other on the conjugate East Greenland margin. Sediment sourced from central East Greenland is distinguished by high garnet:zircon, high rutile:zircon, low chrome spinel:zircon, garnet assemblages rich in low-Ca, high-Mg varieties, and zircon populations that include an Archean group, a diverse range of Early–Middle Proterozoic grains, and an Early Paleozoic group. These features indicate derivation from a high-grade (granulite facies) metasedimentary terrain together with Archean basement and Early Paleozoic granitoids. Norwegian-sourced sandstones differ by having lower garnet:zircon and rutile:zircon, variable chrome spinel:zircon, garnet assemblages scarce in low-Ca, high-Mg varieties, and zircon populations that lack an Archean group. Derivation from the Caledonian Nappe Domain, comprising metasediments (predominantly at amphibolite facies), ophiolites and Early Paleozoic granitoids, is indicated. Initially, during deposition of the non-marine lower part of the Åre Formation (Hettangian–Sinemurian), sediment was fed from the west, but in the upper (tidally influenced) part of the Åre Formation (Sinemurian–Pliensbachian), Norwegian-sourced material appears. Greenland-derived material disappears in the subsequent Tilje Formation (Pliensbachian), with the Tilje and subsequent Ror and Ile Formations (Toarcian–Aalenian) being predominantly sourced from the east. The regional regression at the base of the Garn Formation (Bajocian) was accompanied by a switch in provenance, with Greenland-derived material replacing sediment sourced from Norway. Variations in mineralogy offer a framework for correlation on both local and sub-regional scales.  相似文献   

An evaluation of two alongshore transport equations with field measurements     

B. van Maanen  P.J. de RuiterB.G. Ruessink 《Coastal Engineering》2009

The performance of two well-known equations to predict the depth-averaged alongshore suspended sediment flux [Van Rijn, L.C., 1984. Sediment transport, part II: suspended load transport. Journal of Hydraulic Engineering 110, 1613–1641; and Bailard, J.A., 1981. An energetics total load sediment transport model for a plane sloping beach. Journal of Geophysical Research 86, 10938–10954] was assessed by comparing predictions with 2306 field estimates based on a vertical stack of three optical backscatter sensors and a single electromagnetic flow meter. The observations were collected at four cross-shore positions on the intertidal beach of Egmond aan Zee, the Netherlands, during calm to storm conditions, with the offshore significant wave height peaking at 3.7 m. Measured hydrodynamics were employed in the computations of both models. Also, default parameter values were used without calibration to the data. We found that both models underpredicted the observations. Overall, the Van Rijn model outperformed the Bailard model, with about 70% of the model prediction lying between 1/5 to 5 of the observations under energetic conditions. For the Bailard model this was only about 20%. The performance of the Van Rijn model is, however, sensitive to the wave-related roughness, one of its highly uncertain free parameters. This may allow for an easy calibration when estimates of the depth-averaged alongshore sediment flux are available but may lead to serious errors in situations without data to constrain the predictions. We suspect that the discrepancy between the observations and model predictions is due to an overestimation of the observed fluxes (high turbidity, air bubbles) and an underestimation of the modeled fluxes because of missing physics related primarily to breaking waves.  相似文献   

Laboratory performances of the solar multichannel resonant scattering spectrometer prototype of the GOLF‐New Generation instrument     

S. Turck‐Chize  P.H. Carton  S. Mathur  J.‐C. Barrire  P. Daniel‐Thomas  C. Lahonde‐Hamdoun  D. Loiseau  F. Nunio  Y. Piret  J.M. Robillot 《Astronomische Nachrichten》2008,329(5):521-528

This article quickly summarizes the performances and results of the GOLF/SoHO resonant spectrometer, thus justifying to go a step further. We then recall the characteristics of the multichannel resonant GOLF‐NG spectrometer and present the first successful performances of the laboratory tests on the prototype and also the limitations of this first technological instrument. Scientific questions and an observation strategy are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

榆树林油田低渗透储层微观孔隙结构特征及渗流特性   总被引：5，自引：0，他引：5       下载免费PDF全文

石京平  向阳  张丽萍  王新江  肖鲁川 《沉积与特提斯地质》2003,23(1):90-94

通过对榆树林油田压汞资料的分析，发现该油田的微观孔隙结构参数大部分与中高渗透油层的特征相似，其相对分选系数和结构系数随着渗透率的降低而增大，结构特征参数和孔喉平均半径随着渗透率的降低而减小。在毛管压力曲线上，其排驱压力高，孔喉细小。由于油层的低孔、低渗特性，油、水在孔隙介质中流动，呈现了非线性渗流特征，而且随着孔隙半径和渗透率降低，非线性渗流特征越来越明显。油水两相共同渗流时，束缚水饱和度、残余油饱和度以及共渗点饱和度均较高，而两相渗流范围较小，残余油下水相渗透率较低，最终驱油效率不高。  相似文献   

基于无人机观测的太原夏季PM_(2.5)垂直分布特征及成因分析          下载免费PDF全文

汪文雅  郭伟  王雁  陈玲  王淑敏  成鹏伟 《气象科学》2021,41(4):526-534

利用无人机搭载气象及环境监测设备于2020年7月29—31日在太原进行飞行试验,对不同高度层颗粒物和气象要素进行观测,得到PM_(2.5)三维分布及其随时间的变化特征,并通过气象要素、天气形势和后向轨迹分析得到污染累积和消散成因以及外地传输作用影响。结果表明:PM_(2.5)浓度的垂直分布差异显著,下午大部分时次满足"下高上低"规律,上午边界层垂直混合和颗粒物吸湿增长可能导致"下低上高"的情况;逆温层对大气垂直混合有明显抑制作用;29日为污染物积累过程,30日和31日白天均为消散过程;副热带高压带来的小风、高湿环境是29日颗粒物逐渐累积的原因,30日槽前对流发展和较大的风速有利于颗粒物浓度下降,31日相对湿度较低、对流发展旺盛使PM_(2.5)浓度快速下降;试验期间气流主要来自东南方向,太原市PM_(2.5)本地积累占主导地位,外地传输更多来自于本省晋中、长治等邻近城市。  相似文献   

对流边界层中公路线源扩散的Monte-Carlo法模拟   总被引：2，自引：1，他引：1  

谷德军  刘乙敏  江奕光 《热带气象学报》2000,16(1):38-45

开发了一个Ｍｏｎｔｅ－Ｃａｒｌｏ大气扩散模式且引入了一种检验随机数质量的填充二维点格的方法。通过与水槽试验资料对比,说明该模式具有较好的模拟效果。用该模式模拟公路线源的大气扩散,结果表明,高架路和一般公路的污染在地面浓度上的差异较大,而在垂直方向上差异较小。高架路引起的地面浓度值和扩散范围都较一般公路的大。垂直方向上尤其是２０米以上二者基本没有差异,浓度较大值都在５０～１００米以下。结合箱模式的思  相似文献   

AsteroFLAG: First results from hare‐and‐hounds Exercise #1     

W.J. Chaplin  T. Appourchaux  T. Arentoft  J. Ballot  J. Christensen‐Dalsgaard  O.L. Creevey  Y. Elsworth  S.T. Fletcher  R.A. García  G. Houdek  S.J. Jimnez‐Reyes  H. Kjeldsen  R. New  C. Rgulo  D. Salabert  T. Sekii  S.G. Sousa  T. Toutain  the rest of the asteroFLAG group 《Astronomische Nachrichten》2008,329(5):549-557

We report on initial results from the first phase of Exercise #1 of the asteroFLAG hare and hounds. The asteroFLAG group is helping to prepare for the asteroseismology component of NASA's Kepler mission, and the first phase of Exercise #1 is concerned with testing extraction of estimates of the large and small frequency spacings of the low‐degree p modes from Kepler‐like artificial data. These seismic frequency spacings will provide key input for complementing the exoplanet search data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献