钻孔雷达反射成像在岩溶发育场地探测中的应用

我国岩溶区分布广泛,且复杂的岩溶现象对建筑安全、地基稳定以及场地勘察有较大影响。钻孔雷达作为一种井中地球物理方法,可以利用地下介质的物性差异查明岩溶发育的情况,弥补常规勘察手段在探测岩溶发育场地中存在的不足。依据钻孔雷达单孔反射信号的同相轴特征、反射波首波走时和反射波的衰减等特征,可判断钻孔周边未揭露溶洞和裂隙的分布,确定钻探揭露溶洞的水平方向直径以及岩石完整性,从而达到查明各种岩溶形态的规模、空间密度及其分布规律的目的,为工民建各项工程建设的设计和施工提供准确详尽的地质资料,确保工程的稳定性。      

Near-nucleus imaging of comet IRAS-Araki-Alcock 1983H1

Several digital image processing techniques were used to improve the visibility of details, fans and jets, in the inner coma of the comet IRAS-Araki-Alcock 1983 VII on the short CCD-exposures taken by R. E. Schild with the 61-cm telescope through three I, J, and F band filters, at the Whipple Observatory during the close approach from May 6 through May 12, 1983. About 140 CCD images with the pixel size of 0.73 give a resolution about 20 km, and selected CDD frames presented together with isophotes demonstrate the variation and interrelation of the coma morphology and the nucleus activities during the observing period. Results and processed images are compared with observations taken by other observers during the same period.     

Hard X-ray imaging via focusing optics with mosaic crystals

In spite of the tremendous potential of hard X-ray astronomy (>10 keV) for studying high energy phenomena in celestial objects, the current generation of direct-viewing telescopes is heavily noise limited. It can accurately study only the strongest sources. Thus focusing of hard X-rays is mandatory in order to overcome these sensitivity limitations. Several focusing techniques of hard X-rays (>10 keV) are under study. We will discuss the Bragg diffraction technique and the imaging performance of a concentrator configuration based on this technique. Apart from its unprecedented flux sensitivity, the Bragg concentrators show intrinsic capabilities as polarimeters.     

The university of New South Wales automated patrol telescope

The Automated Patrol Telescope is a wide-field CCD imaging telescope of novel design. The telescope is a converted Baker-Nunn satellite tracking camera that has undergone extensive modification to its optical, mechanical and electronic systems. Telescope operation is entirely under computer control, and the instrument is to be used for a variety of astronomical survey and monitoring projects.     

Ska and Evla Computing Costs for Wide Field Imaging

I investigate the problem of high dynamic range continuum synthesis imaging in the presence of confusing sources, using scaling arguments and simulations. I derive a quantified cost equation for the computer hardware needed to support such observations for the EVLA and the SKA. This cost has two main components – from the data volume, scaling as D⁻⁶ (where D is the antenna diameter), and from the non-coplanar baselines effect, scaling as D⁻², for a total scaling of D⁻⁸. A factor of two in antenna diameter thus corresponds to 12 years of Moore’s law (18 month doubling time) cost reduction in computing hardware. For a SKA built with 12.5 m antennas observing with 1 arcsecond at 1.4 GHz, I find the computing load to be about 150 Petaflops (costing about $500 million in 2015). For 25 m antennas, the load is about 256 times lower, costing $2 million in 2015. This new cost equation differs from that of Perley and Clark (2003), which has scaling as D⁻⁶. This is because I find that the excellent Fourier plane coverage of the small antenna design does not significantly change the convergence rate of the Clean algorithm, which is already satisfactory in this regime.The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation.     

First- and higher-order dynamical controls on water exchanges between tidal basins and the open ocean. A case study for the East Frisian Wadden Sea

Observational data, high-resolution numerical modelling results and a simple analytical theory are combined in this paper to demonstrate the dependence of the volume transports through tidal inlets on topographical or morphological parameters of a Wadden Sea system. The area of interest covers the East Frisian Wadden Sea and consists of seven weakly connected tidal basins. The observations include time series of tidal gauge data and surface currents measured at a pile station in the backbarrier basin of the island Langeoog, as well as several ADCP transects in the Accumer Ee tidal inlet. The numerical simulations are based on the 3-D primitive equation General Estuarine Transport Model (GETM) with a horizontal resolution of 200 m and terrain following vertical coordinates. The model is forced at its open boundaries with sea-level data from an operational model for the German Bight (German Hydrographic Office). The simple theoretical concepts presented illustrate the effect of topography (hypsometry) in the tidal basins on the temporal variability of the exchange of water. This topographic control is effectuated through the bottom slope in the areas prone to drying and flooding. For our study area it takes about twice as long from slack water to maximum flood current than from slack water to maximum ebb current. The underlying physics of this signal modulation from a more or less harmonic forcing at the open-sea boundary and the quantification of the contributing physical processes are the major results of this paper. Estimates based simply on volume conservation are consistent with observations and results from numerical modelling, but they do not completely capture the actual non-linear tidal response. Our analysis shows that at least during part of the tidal cycle characteristic topographic parameters of the inlet/bay system have a major impact on the rate of exchange of waters between the Wadden Sea and the open ocean. This impact is especially strong during the transition between flood and ebb conditions. The possible morphodynamic responses are also addressed focusing on some common (universal) topographic features in seven tidal basins.Responsible Editor: Hans Burchard     

显微CT的发展及其对美容-保健的影响

本文评述美国五家公司的显微CT（以下简称MCT）的现状和发展趋势,在颅凳面病人实际行皮肤切片,显示薄层细胞的基础上,结合MCT做二维和三维的CT成像,成立体,详尽和精确地显示皮肤表层5－10毫米,机体组织三维解剖结构,包括表皮,真皮、脂肪、动脉、静脉的空间分布及其相互关系,探讨显微CT和螺旋CT机在其成像分辨率提高的进程,再现美容病体模型的程度可达到亚微米级的精度,为掌握病情并制定合理的手术计划提供了重要依据,提高－整形的效果,实现全方位扫描和精密三维重建技术在颅凳面皮肤美容和减肥的适应症的应用价值。结果：显微CT三维重建技术是现代皮肤美容和保健的主要诊断方法之一,并具有重要的临床应用价值;近年来工业微焦点CT机其空间分辨率已达5－15微米,已发展了用于生物医学的研究,今后对可皮下组织作精细的CT成像,以了解形整美容,减肥,对当前的美容和保健产品给予在亚微米级,从细胞发育情况的定量评价,表述其CT影像的微观结果。     

电阻率层析成像及演中若干问题的讨论

以双异性点电流源电流场二维地电断面为例，着重讨论了电阻率展析成像反演中有限单元法数值模拟边界条件的选择、网格剖分以及模拟精度等问题，同时也讨论了成像反演中最优化及演方法及拟合参数的评价等。文中提出的新的网格剖分方法和选择的边界条件可有效地提高计算速度和数值模拟的精度。     

我国不同景观区SIR与MSS图像影像特征对比

通过对罗布泊、华北平原、吕梁山、巴丹吉林沙漠、新疆柯坪地区等地区的航天飞机成像雷达(SIR)图像与陆地卫星多波段扫描图像的对比研究,总结了两种图像上风蚀地貌、平原区河流、村镇、黄土高原山地水系以及沙漠、基岩的影像特征,并初步分析了两种图像成像机理,指出了两者解译效果的差异,对不同研究对象选择最佳信息源有一定参考。     

利用成都台网速度量记录测定尾波震级的初步研究

利用成都遥测地震台记录和实量处理系统记录，初步建立了１４个子台速度量记录持续时间测定近层波震级的经验公式ＭＤ＋Ｄ０＋Ｃ１ｌｏｇτ＋Ｃ２ｌｏｇ＾２τ并求得其中的系数Ｃ０，Ｃ１和Ｃ２，使得ＭＤ与全川分析目录结果的地震震级ＭＬ相一致，由于持续时间测定的震级的大小与信号持续时间直接相关，并反映台站附近价质性质，与路径基本无关，不受记录限幅与否的影响，可提高震级测定精度。