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151.
152.
Whitecapping plays an important role in many air-sea exchange and upper ocean processes. Traditionally, whitecap coverage
is parameterized as a function of wind speed only. At present, the relative speed of ocean current to wind is considered to
be important in the air-sea exchange parameterization which is the function of wind speed only. In this paper, the effects
of ocean surface velocity (current velocity and wave induced velocity) and the wave parameters on whitecap coverage through
relative speeds are investigated, by applying a 2-parameter whitecap coverage model to the Atlantic Ocean. It is found that
the impacts of both current and wave on whitecap coverage are considerable in the most part of the Atlantic Ocean. It is interesting
that the effect of wave is more significant than that of current. 相似文献
153.
耦合手机信令数据和房价数据的城市不同经济水平人群行为活动模式研究 总被引:1,自引:0,他引:1
有效分析城市不同经济水平人群的分布特征和活动模式对优化城市资源配置和揭示空间隔离现象有着极高的价值。但人群活动和社会经济等级数据较敏感,使得以往研究仅停留在宏观层面,难以合理划分人群经济等级并对其空间分布和活动模式进行定量分析。本研究以深圳为研究区,基于空间位置关联分析方法,耦合手机信令数据和细尺度房价数据实现了人群经济水平的准确划分,通过计算活动指标定量的分析了不同经济水平人群的空间分布和行为活动特征。研究表明:深圳市不同经济水平人群活动分布与各行政区经济发展相关,呈现“南高北低,西高东低”的格局;深圳市不同经济水平人群之间活动模式存在差异,活动范围、出行距离、出行速度与经济水平存在正向相关;高经济水平人群职住地点相距较远,存在跨行政区分布的现象。本研究分析了城市不同经济水平人群的空间分布特征和活动模式,对城市规划和解决社会不平等问题具有重要的参考价值。 相似文献
154.
本文在分析测绘系统开发与应用中测绘数据的复杂性,以及大部分测绘系统都包含业务流程等特点的基础上,除了RBAC模型的角色授权外,加入了任务对操作进行授权,对RBAC模型进行了有效的扩展,使其更具通用性.该方法有效解决了传统的RBAC模型在测绘系统应用中存在的弊端,对其他应用系统建设同样具有理论指导. 相似文献
155.
The calibration of sedimentary rock absolute dates is one of the difficulties in sedimentological and stratigraphic research. Since strontium(Sr) resides in seawater much longer(≈106 a) than the seawater intermixing time(≈103 a), the Sr isotopic composition of global seawater is uniform at any time and results in a stable system throughout geological history,based on which a global Sr isotope composition dating database has been established for age-calibration of marine strata.The Permian stratigraphic sections in the northern part of the Upper Yangtze block, southern China, record continuous marine sediments with clear stratigraphic boundaries and is suitable for stratigraphic dating of Sr isotopes. Based on sampling and Sr isotopic compositions of Permian carbonate strata in the northern part of the Upper Yangtze, a Permian Sr isotope evolution curve was established. According to the basic principles of Sr isotope stratigraphy, the global Strontium isotope age database can be used to calibrate the Permian stratigraphic dates in the northern Upper Yangtze. The results show that the Sr isotope evolution curves for the marine carbonate rocks in the Permian stratigraphic section of the Upper Yangtze present a decreasing trend from the mid-Qixia stage(P2) to the mid-Wujiaping stage(P3), and then rise from the middle Wujiaping stage to the end of Changxing stage(P3). When the Permian Sr-isotope evolution curve is compared with the global Sr isotope evolution curve in the northern Upper Yangtze, the two are consistent in their long-term evolutionary trend, indicating that Permian global geological events are important controlling factors for the composition and evolution of Sr isotopes. The 87 Sr/86 Sr value decreased gradually in the background of large-scale regressions at the turn of middle to late Permian period, revealing that the Emeishan basalt eruption occurred near the Maokou/Wujiaping boundary(GLB). Srisotope stratigraphy dating was performed on the boundaries of the Qixia Formation/Maokou Formation, Maokou Formation/Wujiaping Formation(GLB), Wujiaping Formation/Changxing Formation(WCB) and the Permian/Triassic(PTB) using the Global Strontium Isotope Age Database. The results are 270.4 Ma, 261.2 Ma, 254.5 Ma and 249.7 Ma,respectively. Based on this, the eruption age of the Emeishan basalts is defined at about 261.2 Ma., which is more coincident with that acquired from other previous dating methods on the eruption age of the Emeishan basalts, and therefore proves that the application of Sr isotopic stratigraphy to dating marine sedimentary units is an effective method. 相似文献
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160.
FY-3微波成像仪遥感图像地理定位方法研究 总被引:1,自引:0,他引:1
MWRI (MicroWave Radiation Imager) is one of the payloads on our next generation polar meteorological satellite FY-3. MWRI conically scans with a fixed incident angle on the earth surface. It is the first time for Chinese remote sensor to use this scan mode. In this work, we present a geolocation method for FY-3 MWRI’s remote sensing image based on its special scan geometry. The integrated coordinate systems and the specific relationships with these coordinate systems are defined. A spatial relationship model between the remote sensing data and the earth-based coordinate system is established. This method also includes an algorithm of satellite orbit computation, which is used to get the satellite’s instantaneous velocity vector from its position. This method has been applied to MWRI’s remote sensing image geolocation. The results show that the accuracy of this method can achieve 1 pixel. The 33 GCPs (Ground Control Points) which are in the regiones of FY-3 MWRI’s observation have been collected and used to analyze the precision of the geolocation. By statistical analysis, the error along-track is about 1.5km, and the error along-scan is about 3.0km. It is obvious that this method fulfills the requirement of precision for FY-3 MWRI whose space resolution exceeds 5km. 相似文献