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911.
杨重谊 《武汉大学学报(信息科学版)》1990,(4)
对于精密重力网,如何确定各类观测值的权,如何剔除相对重力仪过多的参数,是目前尚未解决好的两个问题。本文讨论了利用方差分量估计确定各类观测值的权,利用几种假设检验选择附加参数的方法以及相关的几个问题。经过计算和比较分析,得到了较好的结果。 相似文献
912.
本研究选取黄土高原典型丘陵沟壑区——陕西省米脂县为试验区,用TM磁带、TM假彩色合成影像、SPOT多光谱影像和彩色红外航空像片同时对试区进行土地利用现状分类与制图的比较研究。通过对土地利用现状分类系统、TM图像计算机增强处理与自动分类、TM最佳波段组合、三种影像的目视判读与制图、以及遥感信息源的综合评价等多方面的试验研究,为遥感技术在黄土高原1:5万土地利用现状调查制图中的应用提供了一套技术数据及可行的方法。 相似文献
913.
In this paper,we have suggested several interpolating formulae which are convinient for vector computers to perform vector calculation.Analysis shows that for a simple advective problem,the semi-Lagrangian schemes constructed with these formulae are linearly unconditionally stable.Moreover,we have discussed the nonlinear computational chaos in the semi-Lagrangian schemes.It is found that for a simple nonlinear advective problem,we can introduce physically unreal and direct interaction of three or more waves.Numerical tests indicate that this phenomenon has certain influence on the simulated results of two-dimensional Benard convection. 相似文献
914.
The ordinary multidimensional reductive perturbation method is generalized so as to apply to the general case including the dissipative factor. With this the corresponding Cubic-Schrödinger equation is deduced, and by the preliminary study of its solution, it shows that it is more admissible to consider atmospheric meso-scale systems as the nonlinear Cubic-Schrödinger waves. With suitable boundary and initial conditions, the Cubic-Schrödinger equation is numerically integrated so as to investigate the possible dynamic mechanism as well as the impacts of the nonlinear action, turbulent friction and topogrphy to the formation of the LLJ. The results indicate that the downward transfer of the momentum and the effect of the surface friction are responsible for the concentration of the momentum in the layer between 850 and 700 hPa. The location of the horizontal concentration of momentum depends on the propagation of momentum, in the process the inertia-gravity internal wave is very important, whereas turbulent friction is unfavourable for or delays the formation of the low level jet. 相似文献
915.
本文发展了作者过去的工作(Cai-Liou),利用改进后的数值模式对六角柱冰晶(匀谱和非匀谱)的散射相矩阵进行了计算,所需计算量比Cai-Liou的约小二个量级,且本文的数值模式的结果误差较小。同时,对三棱锥冰晶的散射相矩阵,本文也进行了计算,并与六角冰晶的结果进行了比较。 相似文献
916.
8680X荧光光谱仪采用RSX-11M多用户操作系统。本文将0520计算机作为RSX-11M主机的一个从属终端,设计了相应软件与8680联机。无需修改任何硬件,在0520上可以执行RSX-11M的全部操作指令,并且只要8680主机不关闭,0520计算机即可随时从8680的磁盘上读取数据而不需事先与8680的操作者约定,传送数据快速、准确。 相似文献
917.
918.
Distribution of Hydrogen and Oxygen Isotopes in Salt Lakes of the Qinghai—Xizang Plateau,China 总被引:1,自引:0,他引:1
The Qinghai-Xizang Plateau is an area where a large number of salt lakes are distributed. We have collected several hundred
samples of natural waters over the Plateau since 1976 and carried out researches on their hydrogen and oxygen isotopes. The
results indicate that theδD and δ18O values of the salt lake waters over the Plateau range from −64.1 to +12.4‰ and from −11.19 to +8.62‰, respectively.
From the different types of surfaces, ground and lake waters of various salinities it is inferred that the compositions of
H and O isotopes in the initial water of Qinghai Lake areδD=−55.0‰ and {ie336-1}; and those in the original water from the lakes in northern Xizang, areδD=−116.0‰ and {ie336-2}. Brines in the salt lakes are derived from rain water through prolonged circulation. Oilfield water
also makes some contribution to the salt lakes in the Qaidam Basin. Similar slopes of evaporation lines of water isotopes
are noticed for the Qinghai Lake area and northern Xizang. This is attributed to the evolution of the isotopes in these water
bodies in an environment of middle latitude and high elevation. 相似文献
919.
Summary Formulation and case studies of a three dimensional kinematic model are presented. Thein situ overburden geometry can be simulated accurately and various initiation patterns of blasts can be modelled. The overburden geometry, hole patterns and explosive distribution are all explicit model inputs. Because the effect of explosive properties, rock mass condition and inter-row delay are very difficult to measure in terms of blast performance, these are represented in the model by control parameters which are left for calibration using field data. The output of the model is a three dimensional muckpile shape of any cross section and a contour map of grade distribution within the muckpile. Two case studies are presented which have shown that the model is a valuable tool for optimizing production blasting as well as for controlling grade dilution during blasting. 相似文献
920.
Yang Wu-yang 《GeoJournal》1990,21(1-2):49-55
The objective of this article is to expound the evolution of Beijing's commercial distribution and put the basic facts on the central place model in order to review the past, look upon the present, and predict the future. In terms of the central place theory, the spatial structures and deformations of Beijing's commercial activities are fully discussed, the inherent mechanism on the locational shifts of centers is revealed, and a centripetal zoning concerned with metropolitan commercial system is put forward. Having analyzed the factors of trade and transportation allocation and utilized both qualitative and quantitative methods, the author works out a long-term central place scheme for Beijing's commercial network with a supercenter, Xidan, and other centers of different ranks.Many thanks to Mr. Yang Qi, Ms. Zhou Yu and Ms. Li Xiangming whose map-making, calculating and typing add luster to this article. 相似文献