Mitigation and Adaptation Strategies for Global Change Editorial Policy Update

Mitigation and Adaptation Strategies for Global Change -     

博茨瓦纳欧科范果湿地1972～2000年泛滥方式

欧科范果三角洲地区泛滥范围年年在变化.这种变化与安哥拉高地集水区的区域性降水及当地降雨量有关.我们采用了1972～2000年的3000多幅卫星图像来描绘湿地的格局,其中从1985～2000年的图像几乎是NOAAAVHRR每日连续传送的,1972年以来的其它图像是从Landsat传感器上传下来的,其连续性次之.对AVHRR图像每10天为一期,用无监督分类方法分成陆地和水体.对LandsatTM和ERS2-ATSR数据进行分析的结果,与测算的淹没区域89%相吻合.结果显示欧科范果湿地近期30年期间的变化约在2450～11400km2之间.     

Fluid Mechanics of Biological Surfaces and their Technological Application

 A survey is given on fluid-dynamic effects caused by the structure and properties of biological surfaces. It is demonstrated that the results of investigations aiming at technological applications can also provide insights into biophysical phenomena. Techniques are described both for reducing wall shear stresses and for controlling boundary-layer separation. (a) Wall shear stress reduction was investigated experimentally for various riblet surfaces including a shark skin replica. The latter consists of 800 plastic model scales with compliant anchoring. Hairy surfaces are also considered, and surfaces in which the no-slip condition is modified. Self-cleaning surfaces such as that of lotus leaves represent an interesting option to avoid fluid-dynamic deterioration by the agglomeration of dirt. An example of technological implementation is discussed for riblets in long-range commercial aircraft. (b) Separation control is also an important issue in biology. After a few brief comments on vortex generators, the mechanism of separation control by bird feathers is described in detail. Self-activated movable flaps (=artificial bird feathers) represent a high-lift system enhancing the maximum lift of airfoils by about 20%. This is achieved without perceivable deleterious effects under cruise conditions. Finally, flight experiments on an aircraft with laminar wing and movable flaps are presented.