电离层时空变化效应对星载及月基SAR成像影响:现状与展望

合成孔径雷达（SAR）作为一种主动传感器,具备全天时、全天候的观测能力,已广泛应用于对地观测中.然而,无线电信号在空间传播过程中会不可避免地受到电离层效应的影响,导致信号的相位、幅度发生变化,使得工作在电离层之上的SAR系统的成像性能受到干扰.本文分别从法拉第旋转、背景电离层和电离层不规则体三个方面介绍了电离层效应对不同轨道SAR系统成像性能的影响,并总结了电离层效应的补偿修正方案.最后,给出了电离层效应对星载和月基SAR成像影响的一些亟待解决的问题,以促进星载和月基SAR成像的发展及应用.     

用于油气检测的地震属性差异分析方法——在塔中地区的应用

通过对塔里木盆地巴楚至塔中的12 s深反射地震资料的分析、处理表明,在南北方向上,由和3井经和田1井至和4井基底由北向南逐步抬升,和4井向南基底变深;东西向,巴楚隆起基底较浅,到塔中变深;通过处理可以发现,除了通常可以看到的T4-T9各层反射结构外,在基底以下的深层,还能看到有效的反射;经初步解释和地质分析认为,所处理剖面同相轴连续性好,信噪比较高,归位准确,深层反射信息可靠,剖面所反映的构造形态清楚,规模较大,基本落实了所部署测线工区的地下构造,而且还揭示了一些以前尚未认识到的构造或构造显示,丰富了该区构造特征和构造演化的认识。     

高密度电法在厦-成高速公路段四川大田头大桥勘察中的应用

高密度电法是一种以地球物理为基础,集电剖面和电测深为一体,采用高密度布点,进行二维地电断面测量,研究地下介质体电阻率差异的一种勘查技术.在此,以厦门至成都公路四川境川黔界至纳溪段高速公路C9合同段大田头大桥为例,介绍了高密度电法的基本原理及其在勘查中的应用效果.     

高密度电法评价岩溶地下水分布

本文利用高密度电法对第四系土层进行了勘查,利用所得到的高密度电阻率反演剖面资料,进行了分析,切片,形成等深度的高密度电阻率勘查反演电阻率平面分布,推断地下水的空间活动规律。对利用高密度电阻率勘查推断地下水的空间活动规律进行了一次有益的尝试,为进一步认识地面塌陷和预防治理提供科学依据。     

附壳造型珍珠培育技术研究

比较了不同材料模核、模核规格和植核季节对三角帆蚌和褶纹冠蚌育珠效果的影响。结果表明:贝壳、金属铝、硬塑料和软硅胶模核对三角帆蚌和褶纹冠蚌的成活率和优质珠率存在显著性影响(P<0.05),硬塑料模核的优质珠率最高;不同规格模核对三角帆蚌和褶纹冠蚌的成活率和优质珠率均存在显著性影响(P<0.05),利用复合模核的育珠效果较好,育珠蚌成活率最高可达88%以上,优质珠率最高可达33%;不同季节插核对三角帆蚌和褶纹冠蚌的成活率和优质珠率均存在显著性影响(P<0.05),在春季或秋季进行手术植核,取得的育珠效果较好。     

MAX: Formation flying for nuclear astrophysics

In 2004 CNES decided to perform 4 phase 0 studies dedicated to Astrophysics and achieved thanks to Formation Flying space systems: ASPICS (A Solar Physics Mission to observe in UV and Visible the Solar Corona between 1.01 and 3.2 Solar Radius), PEGASE (an IR interferometry mission to observe Hot Jupiter, Brown Dwarfs and Proto planetary disks), SIMBOL-X (hard X-rays telescope to observe: Accretion onto compact objects, Black Holes, obscured Galactic Nuclei, ˙˙˙˙) and MAX (a Nuclear Astrophysics Mission to observe: Supernovae, Neutron Stars,˙). For this last mission, presented here, two spectral bands around important gamma-ray lines have been selected (450–530 and 800–900 keV). The formation flight allows to realise a long focal length of 80–90 m which is necessary to build a reasonably sized gamma-ray telescope based on a Laue crystal lens. The Space System design allows to have a good spacecrafts mass margin in High Elliptical Orbit with a Soyuz launch (Initial Orbit: Perigee altitude ∼44,000 km and Apogee altitude ∼253,000 km).     

Roche tomography of cataclysmic variables – III. Star-spots on AE Aqr

We present a Roche tomography reconstruction of the secondary star in the cataclysmic variable AE Aqr. The tomogram reveals several surface inhomogeneities that are due to the presence of large, cool star-spots. In addition to a number of lower latitude spots, the maps also show the presence of a large, high-latitude spot similar to that seen in Doppler images of rapidly rotating isolated stars, and a relative paucity of spots at a latitude of 40°. In total, we estimate that some 18 per cent of the Northern hemisphere of AE Aqr is spotted.
We have also applied the entropy landscape technique to determine accurate parameters for the binary system. We obtain optimal masses   M ₁= 0.74 M_⊙, M ₂= 0.50 M_⊙  , a systemic velocity  γ=−63 km s⁻¹  and an orbital inclination   i = 66°  .
Given that this is the first study to successfully image star-spots on the secondary star in a cataclysmic variable, we discuss the role that further studies of this kind may play in our understanding of these binaries.     

V838 Mon: light echo evolution and distance estimate

Following its 2002 February eruption, V838 Mon developed a light echo that continues to expand and evolve as light from the outburst scatters off progressively more distant circumstellar and/or interstellar material. Multifilter images of the light echo, obtained with the South African Astronomical Observatory (SAAO) 1.0-m telescope between 2002 May and 2004 December, are analysed and made available electronically. The expansion of the light echo is measured from the images and the data compared with models for scattering by a thin sheet and a thin shell of dust. From these model results we infer that the dust is probably in the form of a thin sheet distant from the star, suggesting that the material is of interstellar origin, rather than being from earlier stages in the evolution of the star. Although the fit is uncertain, we derive a stellar distance of ∼9 kpc and a star–dust distance of ∼5 pc, in good agreement with recent results reported from other methods. We also present JHKL  and Cousins UBVRI  photometry obtained at the SAAO during the post-outburst second, third and fourth observing seasons of the star. These data show complex infrared colour behaviour while V838 Mon is slowly brightening in the optical.