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31.
研究了1970年以来发生于祁连—海原地震带的18次中强地震序列特征,在此基础上确定了地震序列类型,研究了各种类型地震序列的分布规律.结果表明,该带的18次中强地震序列中有44%为主震型,56%为孤立型.西海固地区的中强地震序列一般为孤立型;101°~103.5°E范围内的祁连山中东段的中强地震序列一般为主震型;99°~101°E范围内的祁连山中段为孤立型和主震型序列并存;99°E以西的祁连山西段的中强地震序列为孤立型.将上述结果应用于2000年6月6日景泰MS5.9地震的震后趋势快速判定,判定结果与实际地震活动情况符合. 相似文献
32.
本文研究了1920年以来,云南地区M_s≥4.7级地震的时间序列及空间分布的特征标度。结果表明,当区内M_s≥4.7级地震在时间序列上出现我们定义的平静段和活跃段后,分别于418天和312天内即可能发生6级以上地震,对应率分别为71%和87%,1920年以来云南11次M_s≥6.8级地震前,出现活跃和平静特征标度的各5次。在空间上绝大多数(80%)大震震中处于我们所定义的长时间大范围空白缺震背景区或相对少震区内,仅少数(20%)位于4.7级以上地震相对密集区内或附近。4.7级以上地震上述时间序列及空间分布特征标度,可以作为云南6级,特别是6.8级以上地震中期或短期预测的判据和指标。同时可以看出,云南6级以上地震前,4.7级以上地震在时空演变上,经历了从无序到有序的演化过程。 相似文献
33.
测量数据可视化技术研究 总被引:3,自引:2,他引:1
介绍可视化的基本原理,阐述中视化研究的必要性,探讨测量数据可视化的技术手段,给出了可视化技术在工作形变监测及工业测量中应用情景,提出一些结论和建议。 相似文献
34.
35.
In usual incoherent scatter data analysis, the plasma distribution function is assumed to be Maxwellian. In space plasmas, however, distribution functions with a high energy tail which can be well modeled by a generalized Lorentzian distribution function with spectral index kappa (kappa distribution) have been observed. We have theoretically calculated incoherent scatter spectra for a plasma that consists of electrons with kappa distribution function and ions with Maxwellian neglecting the effects of the magnetic field and collisions. The ion line spectra have a double-humped shape similar to those from a Maxwellian plasma. The electron temperatures are underestimated, however, by up to 40% when interpreted assuming Maxwellian distribution. Ion temperatures and electron densities are affected little. Accordingly, actual electron temperatures might be underestimated when an energy input maintaining a high energy tail exists. We have also calculated plasma lines with the kappa distribution function. They are enhanced in total strength, and the peak frequencies appear to be slightly shifted to the transmitter frequency compared to the peak frequencies for a Maxwellian distribution. The damping rate depends on the electron temperature. For lower electron temperatures, plasma lines for electrons with a distribution function are more strongly damped than for a Maxwellian distribution. For higher electron temperatures, however, they have a relatively sharp peak. 相似文献
36.
Robin Roth 《Geoforum》2007,38(1):49-59
Community-based mapping has become a necessary tool for development work worldwide - its adoption is near hegemonic. Mapping community land, however, can have unforeseen consequences in part due to its tendency to render what are complex configurations of social-ecological relationships into two-dimensional form. I argue that one of the key limitations to commonly practiced community-based mapping is the assumption that the spatial organization of resource use and management is an abstract entity that can be mapped independent of the social relations that produce it. This paper uses a case study from Northern Thailand to show how mapping techniques that fix and simplify fluid and complex associations can inadvertently prescribe changes to how residents manage their land, effectively becoming not only a tool for securing land tenure but also a tool for the spatial re-organization of land-use and management. 相似文献
37.
G. M. Appleby 《Journal of Geodesy》1998,72(6):333-342
In this paper we describe the results of an analysis of a 2.5-year set of satellite laser range observations of the two Etalon
geodetic satellites. We fit continuous orbits to the range observations, and map the range residuals into series of equivalent
orbital element residuals, considering in detail the orbital longitude, eccentricity and nodal residuals. We use the longitude
residuals to study thermal effects acting on the satellites and compare the results with those published for the Lageos satellites.
We discuss the differences between the two series of eccentricity residuals, and again compare the results with those from
Lageos. Finally we use the nodal residuals to investigate the potential for determination of UT1 of the reference frame defined
by the orbits of the Etalon satellites.
Received: 30 January 1997 / Accepted: 11 December 1997 相似文献
38.
板块构造成矿理论认为西昆仑叶尔羌河中下游地区属于Au、Cu及多金属矿成矿远景区,但因其野外地质条件恶劣,交通状况差,地质勘探极其困难而影响了找矿工作的深入开展,为此我们利用航天遥感技术的优势进行了找矿有利地段预测研究。在研究中首先对区域地质遥感影像特征进行了综合分析,并根据板块构造成矿理论对矿化作用进行了空间划分和成矿条件总结。在此基础上,通过成矿相关影像特征信息的提取,圈定出Au、Cu及多金属矿成矿有利地段。 相似文献
39.
对我国城市化研究的再考察 总被引:13,自引:0,他引:13
本文通过对当前我国城市化研究领域中一些观点的重新考察,以务实的态度提出有关我国城市化进程,城市规模,城市化转移空间,郊区化等问题的探讨性看法,指出城市化既要遵循经济规律,又要发挥政府的适当调控,不拘于西方模式与简单的现象分析,追求城市实质性的健康,有序,持续发展,才是城市化的主旨。 相似文献
40.
P. J. Moran A. R. Breen C. A. Varley P. J. S. Williams W. P. Wilkinson J. Markkanen 《Annales Geophysicae》1998,16(10):1259-1264
EISCAT observations of the interplanetary scintillation of a single source were made over an extended period of time, during which the orientation of the baselines between the two observing sites changed significantly. Assuming that maximum correlation between the scintillations observed at the two sites occurs when the projected baseline is parallel to the direction of plasma flow, this technique can be used to make a unique determination of the direction of the solar wind. In the past it has usually been assumed that the plasma flow is radial, but measurements of eleven sources using this technique have indicated conclusively that in at least six cases observed at mid or high heliocentric latitude there is a significant non-radial component directed in four cases towards the heliocentric equator and in two cases towards the pole. 相似文献