Fine structure of the red giant clump from Hipparcos data, and distance determinations based on its mean magnitude     

Léo Girardi  Martin A. T. Groenewegen  Achim Weiss  & Maurizio Salaris 《Monthly notices of the Royal Astronomical Society》1998,301(1):149-160

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基于Voronoi图的空间邻近定义与查询     

李成名  陈军  朱英浩 《武汉大学学报(信息科学版)》1998,(2)

首先在点Voronoi图的基础上,引进了空间目标的Voronoi图的定义,进而论述了空间目标Voronoi图在GIS中定义空间邻近及其邻近查询中的作用。最后给出了部分实验结果。  相似文献   

地质地球化学图解的计算机绘图系统   总被引：2，自引：1，他引：1  

吕志成  郝立波 《地质与勘探》1998,34(6):37-39

根据目前国内外发表的常用地质地球化学图解特征,研制了一套容纳１５０多幅常用地质地球化学图解的绘图系统。系统界面友好,操作方面,适用性极强,具有可扩充性。  相似文献   

球状星团NGC4147的绝对自行和颜色星等图     

王家骥 Gupta  AC 《天文学报》1998,39(1):67-75

本文以上海天文台佘山40厘米折射望远镜于1958年拍摄的3张照相底片为第一期,印度Kavalur的234米VainuBappu望远镜于1996年用CCD拍摄的4幅图像为第二期,使用Brosche等1985年发表的球状星团NGC4147天区42颗恒星的位置和绝对自行作为参考架,用中心重叠法进行天体测量归算,得到了这个星团中心附近11'×11'天区内到B＝17.6为止115颗恒星的位置和绝对自行,利用这些自行对成员概率作了估计.本文还给出了用VainuBappu望远镜CCD测光结果得到的这个星因水平文和巨星支恒星V与B-V．V－R和V－I颜色星等图,并对这些颜色星等图和团自行作了讨论,得到这个星团的赤经方向绝对自行为-2.82±0.49mas／yr,赤纬方向绝对自行为2.37±0.43mas／yr.  相似文献   

柴达木低品位固体钾矿溶解转化率与品位关系          下载免费PDF全文

王兴富  王石军  王罗海  田红斌  刘万平  刘斌山 《盐湖研究》2020,28(3):61-65

我国是缺钾大国,探明的可溶性钾盐十分有限,柴达木盆地是我国盐湖钾盐的聚集地,含水层骨架中含有数亿吨低品位固体钾矿,开发出这些低品位固体钾盐对增加国内钾肥供给,保障粮食安全具有重大意义。青海盐湖工业股份有限公司历经十年开发出低品位固体钾盐的浸泡式溶解转化方法,试验表明,固体钾盐的溶解转化率随固体钾品位的增加而增加,累计溶解转化率为56%～98%。该技术在柴达木多个盐湖得到推广应用,察尔汗盐湖保有固体钾盐达2.96×10~8 t,平均品位KCl为1.24%,根据试验数据回归分析溶解转化率77%,可溶解转化出钾盐(KCl)约2.28×10~8 t,柴达木盆地盐湖保有3.43×10~8 t固体钾盐,平均品位KCl为1.25%,溶解转化率78%,可溶解转化出钾盐(KCl)2.68×10~8 t,大幅度增加了钾盐储备量。  相似文献   

Analysis of threshold and incipient conditions for sediment movement     

A.A. Beheshti  B. Ataie-Ashtiani 《Coastal Engineering》2008

Prediction of threshold conditions and incipient motion is the essential issue for the study of sediment transport. This work compares existing empirical threshold curves proposed for Shields diagram, a method based on the concept of probability of sediment movement, and an empirical method based on movability number. These methods are used to predict the incipient motion conditions for experimental runs taken from various studies. Most of the experimental data, used in this work, have not been used before in derivation of alternative formulations for Shields diagram and other methods. The empirical threshold curves based on the Shields entrainment function was the least successful at predicting the measured incipient motion conditions, while the use of the movability number gives good predictions of critical shear velocity compared with experimental data.  相似文献   

Application of an ecosystem model for the environmental assessment of the reclamation and mitigation plans for seagrass beds in Atsumi Bay   总被引：1，自引：0，他引：1  

Akio Sohma  Yasuyuki Sekiguchi  Kisaburo Nakata 《Estuarine, Coastal and Shelf Science》2009

An ecosystem model was used to evaluate the effects of reclaiming seagrass beds and creating artificial shallows with seagrass beds to mitigate the effects of the reclamation. The applied model can simulate the pelagic and benthic ecosystems including seagrass beds and tidal flats. The objectives of this study were (a) to investigate the likelihood of cultivating and maintaining seagrass beds in artificial shallows (Part 1), and (b) to understand the effects of the reclamation of seagrass beds and the creation of artificial shallows on the water quality in the estuary (Part 2). In Part 1, first, the nutrient turnover rates due to both biochemical and physical processes in the natural seagrass beds where reclamation is proposed were analyzed. Biological processes rather than physical processes were the most significant driving forces of nutrient cycles in seagrass beds. Second, the effects of filter feeding benthic fauna (suspension feeders) in the seagrass beds were analyzed. The scenario with suspension feeders resulted in higher transparency of the water column (8.7% decrease in the light attenuation coefficient) and an increase in nutrient supply (24.9% increase in NH₄-N in the water column) contributing to the high specific growth rate of seagrass. Third, the specific growth rate of seagrass on the proposed artificial shallows was measured. The value on the artificial shallows set at a depth of datum line minus 0.8 m (D.L. − 0.8 m) was approximately the same as that of the natural seagrass beds. In Part 2, first, water quality in the estuary was compared among the scenarios with/without natural seagrass beds and artificial shallows. Then, the defined values of the water purification capability of (a) artificial shallows with/without seagrass beds, and (b) natural seagrass beds per unit area were evaluated. The reclamation of the natural seagrass beds resulted in a decrease of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a loss in the purification rate). In contrast, the creation of artificial shallows resulted in an increase of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a gain in the purification rate). Based on an annual average, approximately twice as much phytoplankton was removed from the artificial shallows at the depth D.L. − 0.8 m, than at the depth, D.L. − 1.5 m, and the artificial shallows with seagrass beds removed pelagic DIN and DIP at a rate 120% higher than that without seagrass beds.  相似文献   

Exploring the X-ray spectral variability of MCG–6-30-15 with XMM–Newton     

J. Larsson  A. C. Fabian  G. Miniutti  R. R. Ross 《Monthly notices of the Royal Astronomical Society》2007,376(1):348-352

We present a study of the spectral variability of the Seyfert I galaxy MCG–6-30-15 based on the two long XMM–Newton observations from 2000 and 2001. The X–ray spectrum and variability properties of the 2001 data have previously been well described with a two-component model consisting of a variable power-law and a much less variable reflection component, containing a broad relativistic iron line from the accretion disc around a rapidly rotating Kerr black hole. The lack of variability of the reflection component has been interpreted as an effect of strong gravitational light bending very close to the central black hole. Using an improved reflection model, we fit the two-component model to time-resolved spectra of both observations. Assuming that the photon index of the power law is constant, we reconfirm the old result and show that this does not depend on the time-scale of the analysis.  相似文献   

应用岩石热解数据S2-TOC相关图进行烃源岩评价   总被引：1，自引：0，他引：1  

曾花森  霍秋立  张晓畅  鄢仁勤  姜淑杰 《地球化学》2010,39(6):574-579

应用岩石热解数据评价烃源岩的传统方法具有一定的局限性。由于矿物基质的吸附或“死碳”的影响,有机质类型的“范氏图解”往往夸大烃源岩有机质类型的非均质性。对松辽盆地上白垩统不同有机质丰度和有机质类型的烃源岩生烃动力学研究表明,它们具有相似的生烃动力学特征,说明尽管有机质丰度存在较强的非均质性,但其有效源岩类型（区别于应用范氏图划分的有机质类型）是一致的。这些烃源岩的岩石裂解烃（S2）与有机质丰度（TOC）的相关系数很高,与生烃动力学的分析结果一致,表明应用S2-TOC相关图划分烃源岩的有机质类型可以更真实地反映烃源岩的有效源岩类型,S2-TOC相关图是评价烃源岩有效源岩类型的有效手段。过去岩石热解数据用于反映烃源岩成熟度的主要指标是tmax,tmax对于偏Ⅱ／Ⅲ型的烃源岩比较适用,而对于Ⅰ型烃源岩,由于生油窗内变化不明显,tmax不能完全反映有机质的成熟过程;而且tmax也受运移油等其他因素影响。不同成熟度的烃源岩的S2-TOC图分析结果显示,随着成熟度的增加,S2-TOC的回归斜率和TOC逐渐减小;利用不同成熟度的烃源岩建立的S2-TOC图可用于评价烃源岩的成熟度。松辽盆地不同沉积相中烃源岩的S2-TOC相关图的特征表明。只要有有利的有机质保存条件,各沉积相下均可发育优质的烃源岩;S2-TOC相关图可以反映烃源岩形成的沉积环境和有机质保存条件。  相似文献   

长石在高温高压条件下的物理化学行为   总被引：2，自引：0，他引：2  

刘曦  胡张翼  邓力维 《岩石学报》2010,26(12):3641-3650

长石是地学上非常重要的矿物之一。它有可能随着板块俯冲而进入地球深部,因此它在高温高压条件下的相行为以及物理化学性质对地球深部地球动力学研究非常有意义。本文总结了长石端员组份(钾、钠、钙长石)以及其固溶体系列已知的高温、高压实验数据,并绘制成相图。已有的研究成果显示:这三种端员组份在高压下的相行为有较大差异,并产生了许多只在高温高压条件下稳定的相如K-Holl-I、K-Holl-II、CF、CAS及CaPv等。由这些高压相构成的具有长石成分的不同相组合的密度在约5~23GPa的压力范围内超过地幔岩的密度,因此这些相组合可以主动俯冲到上地幔的深处。另一方面,已有研究表明,这些高压相对碱金属及碱土金属在地幔中的赋存状态有着非常重要的影响。  相似文献