Metal contaminants for modelling lobster (Homarus americanus) migration patterns in the Inner Bay of Fundy, Atlantic Canada

A method, which uses metal compositions in lobster digestive glands as natural environmental tags, has been developed to trace lobster movements. Lobsters were collected from three selected sites, Minas Channel, Minas Basin, and Cobequid Bay, Inner Bay of Fundy, New Brunswick, Canada, that were known to be contaminated with Cu. Five metal variables (Ag, Cd, Cu, Mn and Zn) were processed for principal component analysis (PCA). Metal concentration and burden models were investigated and PCA was able to differentiate lobsters from the respective catch sites. The method was applied to investigate the May and June lobsters collected at the three sites to determine the migration rate during this period of the fishing season. The results show a high level of mixing at Minas Basin and Cobequid Bay in June, and lobster movement inward toward the inner reaches of the bay, with very limited movement outward from the inner bay.     

叠前地震数据的平面波深度偏移法

提出了一套基于平面波分解的波动方程叠前地震数据深度偏移方法. 通过对共炮点道集和共偏移距道集地震数据的平面波分解，分别得到适用于单平方根波场外推方程和双平方根波场外推方程的共ps（炮点坐标平面波参数）平面波道集和共ph（偏移距坐标平面波参数）平面波道集. 在对共炮点道集和共偏移距道集地震数据的平面波分解时，不需要进行通常意义下的τ p变换计算. 通过对共ps平面波道集和共ph平面波道集的偏移效果对比，我们认为在速度弱横向变化介质中，两种平面波道集偏移方法的效果相当，但对于速度强横向变化介质，共ps平面波道集偏移方法的效果要优于共ph平面波道集偏移方法. 在计算效率方面，共ps平面波道集偏移方法与共ph平面波道集偏移方法基本相同.     

Gendering transnational communities: a comparison of Singaporean and British migrants in China

Studies of transnational communities and transnational labour migration have focused almost exclusively on the movement of low-skilled and unskilled workers across international boundaries. While these groups may be numerically dominant, it must be recognised that there are increasing numbers of managers and professionals engaged in work-related migration in association with the intensification of economic globalisation processes. Work which has been conducted on highly skilled migrants has largely been limited to examinations of intra-firm mobility and the workspace. This approach fails to consider the ways in which the migrants' experiences are embedded in the social, economic and political practices of the host country, but also in a specific household context. It is unsurprising, therefore, that the gendered dimensions of the life of these migrants and their accompanying family members has been somewhat under-researched.Flows of expatriates can lead to the constitution of both ‘communities of transnationals', as particular cities become foci of the activities of the ‘transnational capitalist class', as well as ‘transnational communities' which involve regular and sustained contact between individuals across national boundaries. In this paper we examine these social formations using two groups of migrants––British and Singaporean migrants to China (both mainland China and the Hong Kong SAR). We focus on the gender characteristics of these groupings, but also the gender division of labour in the creation and maintenance of these ‘communities'. The paper is based on qualitative research carried out in China, Singapore and the UK 1997–2001.     

地震偏移的最优可分近似算法实现

针对地震偏移算法中单程波算子的特征函数近似，采用最优可分表示法将该特征函数展开为空间变量(g)和水平波数(k)的可分表达式，以此可分近似表达式为基础，运用正反Fourier变换重新构造单程波算子. 为了克服特征函数最优可分近似计算在奇点及其领域产生的数值振荡，引入等价黏性技巧以增强算法的数值计算稳定性，并采用分频最优可分及对空间变量(g)线性插值的方法，不仅提高了计算精度，也节约计算机时. 文中具体研究了单程波算子的脉冲响应和二维叠前深度偏移. 结果表明，在不甚大步长情况下，本文构造的算子具有适应横向强变速的能力，运用Marmousi模型验证了本文方法适合复杂构造的成像.     

内蒙古额济纳旗苏泊淖尔石制品的发现及当时的环境特征

在进行地质环境调查过程中,在内蒙古额济纳旗苏泊淖尔Ⅰ级湖积阶地面上发现古人类遗存的石制品,包括石砧、石斧、石片、石核等,大致应属于全新世的遗存。天鹅湖剖面距地表70.5cm深处14C测年结果为4930a±152a,表明该剖面主要形成于全新世,与苏泊淖尔石器的时代相同,其中的记录可反映古人类活动时期的气候特征。据孢粉组合变化可以确定,该区气候总体处于干旱—半干旱状态。剖面下部在相对干旱的背景下显示出一定程度的温湿气候环境,剖面中部则为干旱稳定发展期,成为全剖面干旱程度最强、温度较低的时期,而剖面上部又表现出温度和湿度略有升高的趋势。     

纵横波独立成像的弹性波逆时偏移方法

本文采用逆时递推,在空间域完成纵横波分离,同时实现了位移场成像和纵、横波的独立成像。模拟数据与实际资料试算表明,对纵波和横波分别成像不仅有理论意义,而且有明显的应用价值。文中还就偏移速度对成像结果的影响和实际资料的预处理问题进行了讨论。     

泡塑埋入法找金应用效果及发展前景

本文重点阐明了利用泡塑埋入法找金,从找矿机理和应用效果,均优于土壤测量法。该法能消除“粒金效应”,减少次生晕运移现象,对找隐伏矿体和盲矿体能强化异常,是解决次生晕运移、覆盖厚、找矿难的有效方法之一。在实际找矿应用中,该法具有简单、快速、成本低、找矿周期短、效率高、找矿效果好的特点,获得明显的经济效益和找矿效果。该法进一步改进和完善后,将有广阔的发展前景。     

基于谱分解的断层自动识别

本文在总结国内外地震勘探解释系统的基础上,以物理地震学为理论基础,利用谱分解、地震信号处理中的偏移技术、模式识别中的分级聚类算法和最小二乘法,提出了自动提取断棱衍射、识别断层的思想.仿真结果表明该思想和方法是可行的.本方法还可用于岩性地球物理勘探.     

弹性波克希霍夫积分偏移法

P、S波同时偏移法是为了适应复杂构造地区勘探情况而开始研究的一种偏移方法。在前人工作的基础上,应用弹性波克希霍夫积分偏移的基本原理,改进了纵波（PP）及转换波（PS）的同时克希霍夫积分偏移方法,给出了一种近于实用的计算机流程和程序;并用其分别对射线理论合成反射波资料、有限元模拟地震波传播资料进行了检验,证明此种方法是有效的。在解决复杂构造地区的地震波成象方面,该方法具有很大的潜力。     

迁移八律与中国人口迁移

中国人口迁移具有下列八个特征：１，提高生活质量是经济目的迁移的主要原因，非经济目的迁移违反经济规律时不能巩固；２，在城市化过程中，乡村迁往城市是主要迁移方向；３，整体男性迁移多，轻工劳务和婚姻迁移突出地区女性迁移多；４，独身青年迁移多；５，短距离迁移多，高素质人口迁移距离较长；６，迁移有圈层递补现象；７，强迁移方向必然带来较弱的迁移回流，当两地经济势能接近和递转时，回流加强；８，城市化过程中大城市迁入人口比重大，吸引迁移的范围广。可见，列文斯坦提出的人口迁移规律基本上适合中国的实际，中国人口迁移的实际又丰富了列文斯坦的人口迁移规律。