直接解释地表地质构造的重力异常剖面的近似方法

前言关于求解引起重力异常的地质体形状的问题,在一般情况下还没有直接的解法.对这种问题.为了求得严格的解必须求助于尝试法(迭代法).对于二度地质体,博特(1960)、福尔尼埃和克鲁皮卡(1973)等人曾较详细地讨论过这一问题.对某些理想化的物体,斯基尔斯(1963)还提出了估计最大深度的方法.对于异常地质体的一般形状和密度差作     

ASCA Observation of the Quiescent X-Ray Counterpart to SGR 1627-41

We present a 2-10 keV ASCA observation of the field around the soft gamma repeater SGR 1627-41. A quiescent X-ray source, whose position is consistent both with that of a recently discovered BeppoSAX X-ray source and with the Interplanetary Network localization for this soft gamma repeater, was detected in this observation. In 2-10 keV X-rays, the spectrum of the X-ray source may be fit equally well by a power-law, blackbody, or bremsstrahlung function, with unabsorbed flux approximately 5x10-12 ergs cm-2 s-1. We do not confirm a continuation of a fading trend in the flux, and we find no evidence for periodicity, both of which were noted in the earlier BeppoSAX observations.     

磁层顶的法向和形状

利用ISEE1& 2 ,AMPTE/IRM和IMP8的高分辨率数据 ,以及MV和TD分析法首次给出了在同一辨认原则下找到的所有磁层顶穿越的法线方向 .在此基础上 ,用分段拟合法研究了磁层顶的平均位形 .结果表明 :(ⅰ )大多数磁层顶穿越是切向间断面 ;(ⅱ )赤道面内的磁层顶存在着某种不对称性 ;(ⅲ )无论行星际磁场南向还是北向 ,夜间一侧的磁层顶截面的张角明显大于白天一侧 ,现有经验模型采用的简单单一曲线可能难以完整描述整个磁层顶的位形 .     

Mapsat—一种自动测图卫星系统

<正> 由飞机上或卫星上摄取的立体测图象片,其几何性质已人所共知,并有多种书刊叙述过。把这类象片转换成地图不仅速度慢、成本高,而且在许多重要环节上尚无法实现自动化。与飞机相比,卫星有独特的优点:稳定性更高、速度更均匀。利用这些优点,空间遥感系统目前已能提供具有制图质量的图象了,用连续光电成象系     

用立体正射象片修测地图

<正> 1.前言在发达国家中,摄影测量和制图的主要任务,与其说是地图测制本身,倒不如说是地图修测。人们往往远赶不上理想的修测周期,这周期在三年到十年之间,取决于变化要素的多少。出现正射象片以前,地形图的修测几乎全都使用价格较便宜的摄影测量立体编图仪。同时,很大部分的地图用正射象片进行修测。然而,该方法并非毫无问题,主要由于缺少立体感。     

美国地质测量局使用的地图投影

数十年来,美国地质测量局(USGS)在其制图生产中一直沿用简单的多圆锥投影。目前,它出版的地图,包括国家地图集的地图在内,使用了多种通用投影。其中,横轴墨卡托投影和兰勃特正形圆锥投影是等角的,另一些投影是等积或等距的,还有一些投影,像米勒圆柱投影和格灵登投影是为了使用方便而选用的。某些投影把地球作为圆球,另一些投影则把地球视为圆球或椭球。此外,USGS已经设想和设计出了一些新的投影,其中包括空间斜轴墨卡托投影,这是为卫星图象制图而设计的第一种投影,其连续变形较小。USGS已经为几乎所有这些或另一些投影的正、反算公式编制了程序。这些程序适用于绘图或从一种投影到另一种投影的坐标转换。USGS正准备出版一本综合地图投影手册,它将详细、准确地介绍USGS所使用的全部投影。     

A SHORT NOTE ON THE ACCUMULATION OF ZINC, COPPER AND IRON IN THE POLYCHAETE NEPHTYS HOMBERGI COLLECTED FROM THE TYNE ESTUARY IN ENGLAND

Because of the increasing threat posed by heavy metal pollution of the sea, much work has been done recently to help understand the mechanisms of heavy metal accumulation in marine animals. Some organisms, particularly bivalve molluscs, have received a great deal of attention while other organisms, such as the polychaete Nephtys hombergi, have received little attention. The present brief observations are presented here as one of the first contributions made concerning metal accumulation in this species.     

A New Enantiornithes (Aves) from the Early Cretaceous of China

A new bird from the early Cretaceous Yixian Formation of Liaoning, China is described. This new species, Grabauornis lingyuanensis, shares several synapomorphies with the Enantiornithes. The specimen is relatively well preserved. The skeletal morphology of Grabauornis bears close resemblance to that of other Chinese members of this clade. The brachial index （the ratio between the lengths of humerus and ulna） is 0.95, which is close to the average for enantiornithine birds. It indicates that Grabauornis was a rather good flyer, and the presence of an alula in the wing further testifies to this.