Radial velocity searches for other planetary systems:Current status and future prospects

Measurement of variations in the radial velocities of stars due to the reflex orbital motion of the star around the planetary-system barycenter constitutes a powerful method of searching for substellar or planetary mass companions. After several years of patient data acquisition, radial-velocity searches for planetary systems around other stars are now beginning to bear fruit. In late 1995 and early 1996, three candidate systems were announced with Jovian-mass planets around solar-type stars. The current paradigm for low-mass star formation suggests that planetary systems should be able to form in the circumstellar disks surrounding young stellar objects. These newly discovered systems, and other discoveries which will soon follow them, will test critically our understanding of the processes of star- and planet-formation. We review the techniques used in these radial-velocity searches and their results to date. We then discuss planned improvements in the surveys, and the prospects for the next 20 years.     

Topography as a major factor in the development of arcuate thrust belts: insights from sandbox experiments

We have used sandbox experiments to investigate and to illustrate the effects of topography upon the development of arcuate thrust belts. In experiments where a sand pack shortened and thickened in front of an advancing rectilinear piston, the geometry of the developing thrust wedge was highly sensitive to variations in surface topography. In the absence of erosion and sedimentation, the surface slope tended to become uniform, as predicted by the theory of critical taper. Under these conditions, the wedge propagated by sequential accretion of new thrust slices. In contrast, where erosion or sedimentation caused the topographic profile to become irregular, thrusts developed out of sequence. For example, erosion throughout a hinterland caused underlying thrusts to remain active and inhibited the development of new thrusts in the foreland. Where initial topography was irregular in plan view, accreting thrusts tended to be arcuate. They were convex towards the foreland, around an initially high area; concave towards the foreland, around an initially low area. Initial plateaux tended to behave rigidly, while arcuate thrust slices accreted to them. Thrust motions were radial with respect to each plateau. Within transfer zones to each side, fault blocks rotated about vertical axes and thrust motions were oblique-slip. At late stages of deformation, the surface slope of the thrust wedge tended towards a uniform value. Initial mountains of conical shape (representing volcanoes) also escaped deformation, except at depth, where they detached. Arcuate thrust slices accreted to front and back. Where a developing thrust wedge was subject to local incision, accreting thrust slices dipped towards surrounding areas of high topography, forming Vs across valleys.Arcuate structural patterns are to be found around the three highest plateaux on Earth (Tibet, Pamirs and Altiplano) and around the Tromen volcanic ridge in the Neuquén Basin of northern Patagonia. We infer that these areas behaved in quasi-rigid fashion, protected as they were by their high topography.     

溶液结构的X射线衍射研究──4.用粉末衍射仪精确测定溶液结构的新方法

本文叙述了用θ—2θ型X射线衍射仪精确测定电解质溶液结构的新的实验技术，设计制作了具有恒温功能的超厚液体样品池，并建立了样品池窗口强度的校正方法。建立在Johansson和Yamaguchi工作基础上，发展了液体X射线衍射数据处理和结构参数精细化的计算机程序，获得了非常令人满意的实验结果。由θ－2θ型X射线衍射仪精确测定的径向分布函数与θ－θ型衍射自由表面散射比较，表明DRF分辩率有所提高。     

应用核磁共振成像(NMRI)技术研究复合剂驱油特征

本文应用核磁共振成像技术,在均值、非均值模型中研究了复合剂驱油动态实验过程。观察及分析了复合剂驱油特征和效果,对复合剂驱油段塞前缘进行了实时跟踪,得到了复合剂驱油段塞前缘油墙的形成及剩余油分布与运移的二维图像,给出了复合剂驱油后,剩余油的饱和度分布曲线。实验表明:在层状非均值地层中,若渗透率差异大,复合剂段塞主要进入高渗层,而波及不到低渗层,即复合剂波及效率低。若渗透率差异小,复合剂段塞大部分进入高渗层,有少部分进入低渗层,即复合剂波及效率较高。     

云母石英片岩的三轴蠕变试验研究

在三轴蠕变试验的基础上,通过对径向蠕变和轴向蠕变的比较研究,得出云母石英片岩的蠕变变形和长期强度特点:径向蠕变变形比轴向蠕变变形敏感,以径向蠕变长期强度作为长期强度更合理;围压越大,对径向变形的约束能力越强,径向蠕变长期强度和轴向蠕变长期强度均增加,径向蠕变长期强度与轴向蠕变长期强度的比值减小。同时指出进行径向蠕变研究的意义。     

桂林暴雨天气的多普勒雷达径向速度分析与应用

利用桂林新一带天气雷达径向速度产品资料对2004年发生在桂林的强暴雨过程及其暴雨个例的径向速度平面位置显示产品（PPI）特征的多样性进行分析发现，利用径向速度变化可判断中尺度对流的发展，可对桂林暴雨提前做出预报。     

The visualization of turbulence data using a wavelet‐based method

This technical communication presents some MATLAB^® routines for visualizing the structure in turbulent signals based on a standard conditional averaging and thresholding approach. Up to three velocity components may be analysed and the resulting output highlights the time at which important flow events occur as well as the frequency levels that contribute the greatest energy to this particular event. The latter information is derived from a wavelet decomposition of the signal and may assist in providing a process‐based explanation of observed flow features. Copyright © 2006 John Wiley & Sons, Ltd.     

A formula for computing the gravity disturbance from the second radial derivative of the disturbing potential

 A formula for computing the gravity disturbance and gravity anomaly from the second radial derivative of the disturbing potential is derived in detail using the basic differential equation with spherical approximation in physical geodesy and the modified Poisson integral formula. The derived integral in the space domain, expressed by a spherical geometric quantity, is then converted to a convolution form in the local planar rectangular coordinate system tangent to the geoid at the computing point, and the corresponding spectral formulae of 1-D FFT and 2-D FFT are presented for numerical computation. Received: 27 December 2000 / Accepted: 3 September 2001     

利用GEOSAT／ERM卫星测高数据计算中国近海海平面

本文利用一年（１９８６年１１月８日～１９８７年１１月１７日）２２个ＥＲＭ周期的ＧＥＯＳＡＴ卫星测高数据计算出中国近海海域（１０５°～１３５°Ｅ，０°～４０°Ｎ）相对于ＧＲＳ８０参考椭球面的１°×１°年平均海平面。该海平面我们称之为ＩＧＧＭＳＳ９５平均海平面。在数据处理过程中，由于采用了混合轨道误差模型及交叠平差技术，极大地消除了在误差中占主要成分的径向轨道误差影响，使得ＩＧＧＭＳＳ９５平均海平面的总体精度达到±２０～３０ｃｍ（ＲＭＳ）水平。与ＯＳＵ９１Ａ重力大地水准面模型相比较可以发现两者具有惊人的一致性。     

罗丹宁纤维富集分离－示波极谱法测定地质样品中的金

考察了螯合罗丹宁纤维富集分离。示波极谱法测定Ａｕ的条件，选用０．１５ｇ罗丹宁纤维装柱（Φ５ｍｍ×８０ｍｍ）富集Ａｕ，吸附Ａｕ后的罗丹宁纤维于７００℃灰化的烧，浸取物在ＮａＯＨ底液中用示波极谱法测定。测定范围为０．４～１４０μｇ／ｍｌＡｕ，经对标样分析，结果与标准值相符。对Ａｕ含量为４．９３×１０￣－６级的标样进行１０次测定，方法精密度（ＲＳＤ）为１．１４％。方法选择性高、稳定性好，适用于Ａｕ含量在０。２×ｌ０￣－６以上地质样品的分析。