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881.
喀斯特地貌景观特点及旅游形象塑造 总被引：6，自引：0，他引：6
在分析了喀斯特地貌旅游资源具有的景观特色、竞争特点和环境特点之后,提出喀斯特旅游地形象的塑造应以喀斯特地貌景观的特点为基础,通过对喀斯特旅游地的文脉辨析、形象调查和竞争性分析确定其形象定位,继而围绕其形象定位进行喀斯特旅游地的形象口号设计、视觉形象塑造、行为形象塑造和形象传播策略的选择,并提出在形象塑造过程中要正确处理好与自然景观的协调和喀斯特景观的可持续开发两个问题。 相似文献
882.
883.
Limnological and sedimentary processes at Sawtooth Lake,Canadian High Arctic,and their influence on varve formation 总被引：1，自引：0，他引：1
Pierre Francus Raymond S. Bradley Ted Lewis Mark Abbott Mike Retelle Joseph S. Stoner 《Journal of Paleolimnology》2008,40(3):963-985
This paper synthesizes data collected to document the modern limnological and sedimentary processes in South Sawtooth Lake
located on northern Ellesmere Island, Nunavut, Canada. Field observations show that the finely laminated sediments deposited
in the distal basin are formed by the settling of overflows and interflows, and in rare occasions, by non-erosive hyperconcentrated
density flows. Thin-sections of these sediments allowed for the classification of the sedimentary fabrics into six facies,
each representing different limnological processes. The sediments in this distal basin are considered to be continuous and
annually laminated (varved) based on radioisotope analyses, and both limnological and sedimentological evidence. 相似文献
884.
In case of a complex overburden, the seismic data can be greatly improved by applying a full wavefield redatuming procedure. In practice, the application of the redatuming process to 3-D data acquired by conventional acquisition designs is non-trivial. Because of the large amount of data involved in the 3-D redatuming process and because of the sparseness of these data, it is impossible to apply conventional wave equation datuming directly.
We present a data mapping approach to redatuming (DMR), which follows the concept of Kirchhoff data mapping. A simplified background medium where no ray bending occurs is assumed for the medium below the datum in order to map an input data set referenced to the acquisition surface to an output data set referenced to the new datum level. The DMR method can be interpreted as a simplified version of the Kirchhoff summation redatuming (KSR) method, where one of the 2-D integrals over the acquisition coordinates can be solved analytically. Consequently, in this approach fewer traces are involved in the computation of one time sample (a 2-D integral is computed instead of a 4-D integral), which makes it particularly attractive for the application to 3-D data sets.
In this paper the theory underlying data mapping redatuming is discussed and the proposed approach is tested on fully sampled 2-D and 3-D synthetic data from models with both simple and complex velocity distributions in the subsurface.
The tests clearly show that the objective of producing results that are comparable to the conventional KSR has been achieved. The redatumed traces are dynamically and kinematically correct. Furthermore, these results confirm that the dependency of the new approach on the assumed medium below the datum level is, indeed, weak because the assumption of a velocity medium where no ray bending occurs is already sufficient to produce correct results. 相似文献
We present a data mapping approach to redatuming (DMR), which follows the concept of Kirchhoff data mapping. A simplified background medium where no ray bending occurs is assumed for the medium below the datum in order to map an input data set referenced to the acquisition surface to an output data set referenced to the new datum level. The DMR method can be interpreted as a simplified version of the Kirchhoff summation redatuming (KSR) method, where one of the 2-D integrals over the acquisition coordinates can be solved analytically. Consequently, in this approach fewer traces are involved in the computation of one time sample (a 2-D integral is computed instead of a 4-D integral), which makes it particularly attractive for the application to 3-D data sets.
In this paper the theory underlying data mapping redatuming is discussed and the proposed approach is tested on fully sampled 2-D and 3-D synthetic data from models with both simple and complex velocity distributions in the subsurface.
The tests clearly show that the objective of producing results that are comparable to the conventional KSR has been achieved. The redatumed traces are dynamically and kinematically correct. Furthermore, these results confirm that the dependency of the new approach on the assumed medium below the datum level is, indeed, weak because the assumption of a velocity medium where no ray bending occurs is already sufficient to produce correct results. 相似文献
885.
Variations of horizontal and vertical velocities over two-dimensional transverse dunes: A wind tunnel simulation of the effect of windward slope 总被引：2，自引：0，他引：2
The changes in wind velocity induced by dune topography have an important significance in dune dynamics. In this paper, the horizontal and vertical velocities over six transverse dune models were measured non-intrusively by means of Particle Image Velocimetry in a wind tunnel. The windward slope angle and the free-stream wind velocity both affected the horizontal and vertical velocity components. On the windward side, the acceleration of horizontal velocity depended mainly on the windward slope angle and the height above the dune surface, but was also affected by the free-stream wind velocity. The speed-up ratio increased with increasing slope angle but decreased with increasing height. The ascending vertical velocities also increased with increasing slope angle and free-stream wind velocity. The maximum values moved upper along the dune when the windward angle became steeper. In the leeward sides, the horizontal velocity decreased and reversed because of airflow separation; the maximum reverse velocity in the separation cell was about 17% of the free-stream wind velocity. Behind the dune crest, the airflow moves downwards, and its maximum downward velocity is found near the flow reattachment point. Finally, we discussed the significance of these velocity variations for sediment transport and dune dynamics. 相似文献
886.
我国利用遥感数据提取土地利用现状信息的技术进展 总被引：30，自引：3，他引：27
结合作用所参加的研究工作,探讨了我国近年来利用遥感数据获取土地利用现状信息的技术方法的阶段性发展规律,并对其发展趋势做出了预测。 相似文献
887.
影像匹配中金字塔数据结构比较与快速算法 总被引：10，自引：0，他引：10
分析了多种金字塔数据结构的生成方法 ,比较了不同方法在影像匹配中的优劣 ,并提出了一种影像金字塔生成的快速算法。 相似文献
888.
城市灾害现场图像传输系统的技术选择——以厦门市为例 总被引：2，自引：0，他引：2
以厦门市为例,介绍了灾害应急指挥通讯系统在实施灾害救援时依据无线电传输特性所作的技术选择。主要可归纳为：①现场图像至现场应急指挥车间的微波模拟传输。选择穿透能力较强的频道,实测无阻挡时可传输8km,有阻挡情况下穿透3、4堵墙壁;②现场指挥车至城市应急指挥中心间的甚高频数字化传输。在经过城市实际电磁空间噪音场扫描后选定适宜的频道窗口,以实现10km左右的传输要求：③现场应急指挥车在有条件的场地也可接驳宽带电话网实现与城市应急指挥中心的图像传送。 相似文献
889.
890.
珊瑚的影像密度恢复南海海表温度 总被引：7，自引：0，他引：7
将南海西沙永兴岛 ( 1 6°50′N,1 1 2°2 0′E)西北的造礁珊瑚的岩芯 ,制成 X射线负片。用显微光密度计在 X射线负片上获得沿生长轴方向的影像密度值 ,时间序列为 1 937～ 1 993年。根据影像密度数据 ,计算出珊瑚的各年生长率和钙化率的代用指标。珊瑚生长率和钙化率的代用指标都与 SST呈显著正相关。根据 1 960～ 1 993年的资料统计 ,相关系数分别是 0 .91和 0 .85,从而建立了珊瑚生长率温度计和钙化率代用指标温度计。并用这两个温度计测算到 1 937年 ,揭示出南海的 SST变化既受到全球气候环境变化为主的影响 ,也受到半封闭海域格局的影响 相似文献