阿尔金北缘岩石变形机制——来自X光组构分析的证据

对阿尔金北缘地区变形蚀变花岗岩、花岗质糜棱岩、变形酸性火山岩和变形英安质凝灰岩中石英和绢云母2种矿物进行X光岩石组构分析,认为本区岩石变形比较明显,宏观面理近于东西向展布,绢云母变形较强,平行于面理定向排列;而石英以底面或近底面滑移为主,部分样品兼有柱面Ⅰ型滑移和柱面Ⅱ型滑移,反映本区岩石变形机制为中浅层次的脆-韧性变形(10~15km、250~350℃、0.25~0.40GPa)。通过岩石组构特征与宏观面理产状,推断本区韧性变形以右行运动为主,与板块碰撞在阿尔金北缘大平沟地区产生的韧性变形带特征一致。     

New variogram modeling method using MGGP and SVR

A critical step for kriging in geostatistics is estimation of the variogram. Traditional variogram modeling comprise of the experimental variogram calculation, appropriate variogram model selection and model parameter determination. Selecting of the variogram model and fitting of model parameters is the most controversial aspect of geostatistics. Shapes of valid variogram models are finite, and sometimes, the optimal shape of the model can not be fitted, leading to reduced estimation accuracy. In this paper, a new method is presented to automatically construct a model shape and fit model parameters to experimental variograms using Support Vector Regression (SVR) and Multi-Gene Genetic Programming (MGGP). The proposed method does not require the selection of a variogram model and can directly provide the model shape and parameters of the optimal variogram. The validity of the proposed method is demonstrated in a number of cases.     

Retrospective analysis of diversity and species composition of marine macroalgae of Hainan Island (China)

Retrospective analysis of diversity and species composition of marine macroalgae of Hainan Island in the period 1933–1992 is presented in this paper. There are two extensive sample collection periods of benthic macroalgae: the early collection (EC) covers a period between the early 1930s and the 1980s before considerable urbanization and reef degradation took place and a late collection (LC) was performed in 1990/1992 during a phase of rapid urbanization. Analysis of data also including an earlier published inventory of green algae covering the same collection sites (Titlyanov et al. 2011a) revealed that the marine flora of the island comprises 426 taxa in total, with 59% red algae, 18% brown algae and 23% green algae. In total 59 species of red algae, 11 species of brown algae and 37 species of green algae sampled during the LC are new records for Hainan Island. Considerable floristic changes between EC and LC became evident. In the LC there were significantly more filamentous, tubular or fine blade-like, and often epiphytic, green and red algae with a high surface-to-volume ratio. Additionally a reduction of green, brown and red algal species with larger fleshy or foliose thalli and a low surface-to-volume ratio was observed. It is assumed that the changes reflect the degradation of the coral reef ecosystem around Hainan, which was damaged by human activities especially in the 1950s–1970s.     

应用两次展开法求解系泊柱体慢漂运动方程

在深海中系泊的海洋平台,如Spar平台,水下部分为带有系泊的圆柱结构,其水平方向运动响应往往具有较低的自振频率,容易在低频波浪力(源于非线性的差频效应)作用下发生共振响应,使结构发生大幅水平慢漂。当浮体的瞬时位置大幅偏离初始位置时,基于初始平衡位置的摄动展开法会存在较大误差。针对这一问题,采用两次展开方法,对大幅慢漂运动开展时域模拟研究。对双色波作用下自由漂浮圆柱的大幅运动响应问题进行数值分析,并与采用基于初始平衡位置的摄动展开法的计算结果进行了对比。结果表明,采用新的两次展开法可以计算出波浪遭遇频率的变化和波浪漂移阻尼,而这无法从基于初始平衡位置的常规摄动展开法中得到,体现了两次展开法在分析大幅慢漂问题上的优势。