首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4篇
  完全免费   7篇
地球科学   11篇
  2015年   1篇
  2014年   2篇
  2013年   1篇
  2012年   1篇
  2009年   2篇
  2008年   1篇
  2003年   1篇
  1997年   1篇
  1996年   1篇
排序方式: 共有11条查询结果,搜索用时 46 毫秒
1.
潮汐汊道A-P关系中参数Cn的控制因素   总被引:7,自引:0,他引:7       下载免费PDF全文
与沿岸漂砂相联系的潮汐汊道系统达到均衡态时的A-P关系可表示为A-CP^n。根据对A-P关系的模拟,本文提出在均衡条件下n值必然大于1,潮汐汊道A-P关系表现出弱分形现象。其原因是对应于一定强度的沿岸漂砂较小汊道以口门宽度减小,流速增大来维持均衡关系。模拟实验还表明,参数C的大小与沿岸输砂率、淡水径流量和潮汐类型有关,这些因素对参数n稍有影响。前人研究有时遇到n〈1的情况,这可能是由于统计分计的某  相似文献   
2.
二维表面波破碎面分形结构   总被引:2,自引:0,他引:2       下载免费PDF全文
本文利用非线性理论,在各组成波空间特征尺度可分离情况下,推广了Longuet-Higgins(1994)最新结果,并在某些可允许条件范围内,利用n次骑波能量方程,给出了n-1次骑波关于n次骑波扰动失稳条件。由失稳条件及破碎波动力机制,分析了二维表面波破碎面的拓扑结构,并给出了计算该破碎面分形维数表达式。最后,通过一具体实例,来进一步解释破碎面分形拓扑结构。  相似文献   
3.
The surface roughness characteristics(e.g., height and slope) of sea ice are critical for determining the parameters of an electromagnetic scattering, a surface emission and a surface drag coefficients. It is also important in identifying various ice types, retrieval ice thickness, surface temperature and drag coefficients from remote sensing data. The point clouds(a set of points which are usually defined by X, Y, and Z coordinates that represents the external surface of an object on earth) of land fast ice in five in situ sites in the eastern coast Bohai Sea were measured using a laser scanner-Trimble GX during 2011–2012 winter season. Two hundred and fifty profiles selected from the point clouds of different samples have been used to calculate the height root mean square, height skewness, height kurtosis, slope root mean square, slope skewness and slope kurtosis of them. The root mean square of the height, the root mean square of the slope and the correlation length are about 0.090, 0.075 and 11.74 m, respectively. The heights of 150 profiles in three sites manifest the Gaussian distribution and the slopes of total 250 profiles distributed exponentially. In addition, the fractal dimension and power spectral density profiles were calculated. The results show that the fractal dimension of land fast ice in the Bohai Sea is about 1.132. The power spectral densities of 250 profiles can be expressed through an exponential autocorrelation function.  相似文献   
4.
应用分形理论分析了防城港湾红树林表层沉积物粒径分布及其分形特征,并分析了pH值、C有机质、C硫化物、CTN、CTP、CK、水溶性盐分等环境因子.沉积物由海向陆的砂含量减少,细砾、粉砂和粘土含量增多,平均粒径也呈渐次增大.沉积物分选性都是差到很差,偏态都是正偏态到很正偏态,峰态都是中等尖锐到很尖锐.沉积物各粒径含量与pH值、有机质、硫化物含量相关关系不明显,砂、粉砂含量与CTN、CTP、CK呈显著相关关系.沉积物的分形维数为2.322 1~2.649 1,分维值与环境因子相关关系不明显,与粘土含量呈显著正相关(R=0.978,p<0.01).沉积物分形值呈含砾砂(2.322 1)<含砾泥质砂(2.513 0~2.618 1)<含砾泥(2.649 1)的趋势.不同滩位的红树林沉积物分形维数呈现向海侧红树林外光滩(2.322 1~2.5602)<向海侧红树林林带(2.513 0~2.5909)<红树林林带中心(2.557 0~2.595 6)<向陆侧红树林带(2.618 1~2.649 1)的规律.沉积物类型、粘土组分、滩位等是影响防城港湾红树林沉积物分形维数的主要环境因子.  相似文献   
5.
文章利用分形维数理论对我国主要类型的海岸线进行了抽样分析,总结其中的规律并给予相应的解释,以此为依据提出了可量化的海岸线分类方式,初步建立其与传统海岸线分类方式的关系。同时,以海岸线的分形维数特征为依据对海岸线变化的发展趋势进行定量分析,提出以分形维数作为衡量海岸带开发程度量化指标的理论。  相似文献   
6.
将分形理论应用于溢油的气相色谱鉴别,建立了一种新的海洋溢油气相色谱鉴别方法。即首先采用小波分解将气相色谱图曲线分解至不同的尺度,计算各尺度曲线分量的分形维数,基于分形维数参量,采用欧几里得距离判断不同样品气相色谱曲线的近似程度,达到对溢油样品进行鉴别的目的。溢油事故实例数据分析表明,分形维数能较好的反映不同色谱曲线的差异,所建立的方法在筛选溢油样品时,能在一定程度上缩小鉴别范围,可作为溢油鉴别的一种有效辅助方法。  相似文献   
7.
Sediment cores were collected from the subaqueous delta of the Changjiang Estuary. Sediment grain-size profiles and their fractal dimensions were analyzed, to elucidate responses to long-term sedimentary processes. In addition, the environmental sensitive populations of grain size have been extracted. The sediment cores can be divided into two parts, according to the sedimentary structures present. The upper part (0-12 cm) is interpreted as being the active layer, which is influenced frequently by changes i...  相似文献   
8.
胶州湾海岸线历史变迁的分形分析   总被引:3,自引:0,他引:3  
使用网格法以1987-2006年间5景经过精确校正的Landsat-TM遥感图像为基本资料,计算出了胶州湾海岸线的分形维数,其值为1.090 1(1987年),1.090 3(1992年),1.082 9(1997年),1.076 2(2003年)和1.080 1(2006年).结果表明,1987-2006年胶州湾海岸线分形维数先后经历了缓慢增大、减小、再增大的三个变化阶段.胶州湾较大规模的海岸工程是其岸线分形维数减小的主要原因,而较小规模的海岸工程和自然过程则是其分形维数增大的原因.  相似文献   
9.
借助GIS ArcView软件分析提取黑潮锋区域,将一定间隔的经纬度点的温度值生成等值线以此为研究对象,应用网格法计算了20°~30°N,120°~130°E范围内黑潮锋区50m和100m深处水温的分维值,100m深处的分维值波动较50m深处小,但整体上分维值较50m深处大。计算结果符合黑潮锋区强度的实际分布情况,初步认为分形维数能够表征黑潮锋强度,分维值随黑潮锋强度的增大而增大。  相似文献   
10.
黄河三角洲区域水动力条件下岸滩侵蚀研究   总被引:1,自引:1,他引:0       下载免费PDF全文
An ideal nature system for the study of post-depositional submarine mass changing under wave loading was selected in the intertidal platform of the subaqueous Huanghe River Delta, a delta formed during period from 1964 to 1976 as the Huanghe River discharged into the Bohai Gulf by Diaokou distributary. A road embankment constructed for petroleum recovery on the inter-tidal platform in 1995 induced the essential varieties of hydrodynamic conditions on the both sides of the road. With both sides sharing similarities in (1) initial sedimentary environment, (2) energetic wave loading, (3) differential hydrodynamic conditions in later stages, (4) enough long-range action, and (5) extreme shallow water inter-tidal platforms; the study is representative and feasible as well. Two study sites were selected on each side of the road, and a series of measurements, samplings, laboratory experiments have been carried out, including morphometry, hydrodynamic conditions, sediment properties, granularity composition, and fractal dimension calculation of the topography in the two adjacent areas. It was observed that in the outer zone, where wave loading with high magnitude prevailed, the tidal flat was bumpy and exhibited a high erosion rate and high fractal dimension. Further, the fractal dimension diminished quickly, keeping with the enlarging of calculative square size. However in the inner zone, where the hydrodynamic condition was weak, the tidal fiat was fiat and exhibited a low erosion rate and low fractal dimensions; the fractal dimension diminished with the enlarging of calcu- lative square size. The fractal dimensions in the different hydrodynamic areas equalized increasingly as the calculative square size accreted to threshold, indicating that the hydrodynamic condition plays a significant role in topography construction and submarine delta erosion process. Additionally, the later differentiation of sediment properties, granularity composition, microstructure characteristics, and mineral composition  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号