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711.
本文通过对纳尔逊冰帽冰面速度和应变率的分析,得出冰帽边缘的最大夏季表面速度为2058m/a,最大年平均表面速度为15.5m/a,探求了冰面运动速度的空间分布和季节性变化,冰帽顶部的表面应变率为+0.0079/a和+0.0034/a。还讨论了冰面应变率从冰帽顶点到边缘的变化特点及其与冰面裂隙的关系。并将这些特征同我国大陆型冰帽进行了对比,从冰川动力学的角度阐明了纳尔逊冰帽的某些特征。  相似文献   
712.
当今,国内外十分重视金刚石表面处理技术,它可以用少量投资和简单的工艺方法,使金刚石性能得到改善。常用的处理技术有:①电镀法;②真空镀法;③扩散渗覆法;④气相沉积法;⑤离子镀法;⑥化学镀法。  相似文献   
713.
通过实践发现:(1)洗井液中的表面活性剂可以提高金刚石钻进的机械钻速。但表面活性剂和岩石种类不同,其提高幅度也不同;(2)钻速随阴离子表面活性剂(?)电位值的提高而增加;(3)表面活性剂对岩石微裂纹的渗透作用有助于提高钻速。  相似文献   
714.
微量元素与矿物表面反应研究进展   总被引:4,自引:0,他引:4  
微量元素与矿物表面反应研究进展吴宏海吴大清(中国科学院广州地球化学研究所,广州510640)关键词矿物—水界面表面反应表面络合模式微量金属元素1研究意义与现状在地表环境中,大气圈、水圈和岩石圈之间存在着相互进行物质传输与能量交换的界面作用,其中矿物...  相似文献   
715.
ECOLOGICALLY STRATEGIC POINTS IN LANDSCAPE AND SURFACE MODEL   总被引:2,自引:0,他引:2  
YuKongjian 《地理学报》1998,53(B12):19-20
Various processes occur across a landscape, including ecological processes such as the movement of species, the flow of nutrients, the spread of fire and other disturbances, and the diffusion of pollutants, economic processes such as land conversion for agricultural production, marketing of new product, transportation and immigration; political and diplomatic processes such as the construction of political influence sphere at local, national and global scale. At the fact of limited space and resources on the surface of the earth, a generic issue regarding these processes across the landscapes is: how to control (promote or retard) the processes efficiently, namely using less energy and space for a bigger influence sphere. The overall assumption for this issue is that, there are some positions and portion in a landscape that may have critical influence on a certain process across the landscape. These critical positions in a landscape are called strategic points. Occupancy of these strategic points may give a process the momentum of controlling and covering the landscape more effectively, due to their quality of; Initiative, occupancy of these points may give the process the advantage of leading the game; Co-ordlnation, occupancy of these points may give the process the advantage of forming an overall influence sphere; Efficiency, occupancy of these points may give the process the advantage of having a bigger coverage of the landscape while costing less energy. By identifying and using these critical positions and portions in the landscape, therefore, may unproportionately increase the efficiency of controlling this process. It is further assumed that, in order to take control of the landscape, the process has to overcome a certain resistance. A resistance surface can therefore visualize the dynamics of the process itself. The resistance surface resembles a topographic surface, indicating where the process (flow) diverges or converges. It is, therefore, possible to identify strategically important positions or portions in a landscape that may have important influence on the dynamics of the process. Assuming species movement across a landscape is a competitive gaming process of control and coverage against some resistance, this paper discusses a methodology of identifying strategic points according to the properties of resistance surfaces which resembles a gaming board as well as a topographic surface. Three types of resistance surfaces are discussed: The archipelago type: where lower resistance islands are surrounded by higher resistance matrix, representing such landscapes as agricultural fields dotted with native forest patches. The network type: where the lower resistance portions form a linear network surrounded by higher resistance matrix. The plateau type: where, areas with higher resistance are surrounded by lower resistance matrix. Accordingly, five types of strategic points are identified in terms of their locations. They are strategic points at saddle points , at intersections, at the center, at an edge and at a corner. Strategic points for biodivershy conservation are minimax points in a given resistance surface associated with the dispersibility of a certain species. A case study is used to illustrate the methodology. The rules leading to the strategic points are largely hypothetical, though supported by a limited number of observations. This approach may provide a framework and a new model of thinking for field observations of landscape ecology as well as landscape change.  相似文献   
716.
景观生态战略点识别方法与理论地理学的表面模型   总被引:30,自引:0,他引:30  
俞孔坚 《地理学报》1998,53(B12):11-18
本文讨论了如何根据景观阻力表面特征来判别景观生态战略点的方法,论述了三种类型的景观阻力表面;岛屿型、网络型和高原型。相应于各种阻力表面类型,得出五种景观战略点的空间位置:鞍部战略点.交汇处战略点,中央战略点,边缘战略点和角落战略点。  相似文献   
717.
腾格里沙漠东南缘格状沙丘粒度特征与成因探讨*   总被引:21,自引:4,他引:17  
哈斯 《地理研究》1998,17(2):178-184
腾格里沙漠南缘格状沙丘表面沉积物的系统采样分析结果表明,粒径与分选参数在沙丘断面具有规律变化是形态-气流相互作用的结果.文中根据沙丘形态和气流状况,对格状沙丘成因及类型归属等问题作了探讨.认为格状沙丘发育在双向低风能环境,其中主梁为主风(西北风)作用下形成的横向沙丘,副梁则发育在主梁基础上并受制于主风和次主风(东北风)交替作用,在形态,沉积和动力学方面具有纵向要素特征.因此,该区格状沙丘属纵向要素叠置于横向沙丘之上的一种复杂型沙丘.  相似文献   
718.
通过同化系统将观测资料与海洋数值模式融合得到的海洋再分析产品为海洋科学研究提供了重要的资料基础.本文采用WOA,SODA,AVISO和GLORS四种数据资料与我国自主研发的中国全球海洋预报系统(CGOFS)的气候态结果进行了对比,结果表明:CGOFS和SODA的全球海表面温度与WOA的均方根误差分别为0.51和0.43℃.CGOFS和SODA的海表面盐度与WOA的均方根误差分别为0.48和0.40 PSU;海流方面,CGOFS能较好的刻画主要大洋环流分布及赤道潜流的垂向结构;CGOFS的全球海表面高度异常与AVISO的均方根误差为0.018m;多年月平均海冰外缘线覆盖面积介于SODA和GLORS之间,海冰体积的生消规律与SODA和GLORS一致.总体来看,CGOFS全球高分辨率海洋再分析产品的气候态结果与国际同类产品基本一致,可为提升我国海洋综合科技实力提供可靠的资料保障.  相似文献   
719.
As water depth increases, the structural safety and reliability of a system become more and more important and challenging. Therefore, the structural reliability method must be applied in ocean engineering design such as offshore platform design. If the performance function is known in structural reliability analysis, the first-order second-moment method is often used. If the performance function could not be definitely expressed, the response surface method is always used because it has a very clear train of thought and simple progranuning. However, the traditional response surface method fits the response surface of quadratic polynomials where the problem of accuracy could not be solved, because the true limit state surface can be fitted well only in the area near the checking point. In this paper, an intelligent computing method based on the whole response surface is proposed, which can be used for the situation where the performance function could not be definitely expressed in structural reliability analysis. In this method, a response surface of the fuzzy noural network for the whole area should be constructed first, and then the structural reliability can be calculated by the genetic algorithm. In the proposed method, all the sample points for the training network come from the whole area, so the true limit state surface in the whole area can be fitted. Through calculational examples and comparative analysis, it can be known that the proposed method is much better than the traditional response surface method of quadratic polynomials, because, the amount of calculation of finite element analysis is largely reduced, the accuracy of calculation is improved, and the true limit state surface can be fitted very well in the whole area. So, the method proposed in this paper is suitable for engineering application.  相似文献   
720.
胶州湾海水中阴离子表面活性剂的含量及分布   总被引:6,自引:3,他引:6  
根据2003年5月和8月对胶州湾进行的两次现场调查,采用亚甲基蓝分光光度法测定了该海域海水中阴离子表面活性剂含量并初步分析了其分布特点。结果表明,2003年5月胶州湾全湾表层海水中阴离子表面活性剂平均浓度为12.6μg/L,略高于8月份(10.3μg/L);各站位含量有变化,河口及邻近海域站位高于其他站位;表层海水含量高于底层海水。  相似文献   
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