Os isotopic composition of the earth’s primitive upper mantle

The osmium isotopic ratio of¹⁸⁷Os/¹⁸⁸Os ranging from 0.126 to 0.127 for the primitive upper mantle (PUM) is obtained according to the correlation between¹⁸⁷Os/¹⁸⁸Os and Al₂O₃ of mantle-derived xenoliths and orogenic peridotites, which consists with Allegre and Luck’s ALM value and similar to Yin’s nuggets uniform reservoir (NUR) value. It shows that the Os isotope ratio is lower than enstatite or ondinary chondrites, similar to carbonaceous chondrites (CV3).     

醋酸甲酯催化精馏水解塔的模拟

以平衡级模型用块状三对角矩阵技术,对强极性的醋酸甲酯催化精馏水解过程进行模拟,在改变空速、水酯比、回流比等操作条件以及塔板数下,用模拟的酯水解率、塔内温度、水解液的酸水比与实验值进行了比较,结果令人满意     

杭州湾北岸漕泾-柘林近岸海域浮游生物的调查

1996年11月和1997年3月,对漕泾－柘林的近岸海域的浮游生物进行了调查,1996年11月浮游植物平均密度为3．39×104个／L,密集于高潮带,主要有舟形藻、圆筛藻、直链藻等5种藻类,舟形藻为优势种;1997年3月平均密度为1．65×104个／L,密集于潮下带,主要有囊裸藻、针杆藻、小球藻等7种,囊裸藻为优势种．1996年11月,浮游动物的平均个体数为2．84×102个地,原生动物为优势种类;1997年3月,平均个体数为1．83×102个／L,以多毛类疣足幼虫为主;两次调查时浮游动物都密集于低潮带．     

中国健康中老年男性血沉参考值与地理因素的关系

为制定中国健康中老年男性血沉参考值（温氏法）的统一标准提供科学依据,本文收集了中国各地测定的健康中老年男性血沉参考值（温氏法）,并对其与地理因素的关系进行了研究,发现海拔高度是影响健康中老年男性血沉参考值（温氏法）最主要的因素,随着海拔高度的逐渐增大,健康中老年男性血沉参考值（温氏法）在逐渐的减小,相关性很显著．用逐步回归分析的方法推导出了一个回归方程,如果知道了中国某地的地理因素,变可以用这个回归方程估算这个地区的健康中老年男性血沉参考值（温氏法）,依据健康中老年男性血沉参考值（温氏法）与地理因素的依赖关系把中国分为青藏区,西南区,西北区,东南区,华北区,东北区等六个区．     

一阶非线性时滞系统的渐近性和振动性

讨论了一阶非线性具有变号系数的滞系统解的渐近性和振恸 性,得到了几个充分条件和必要条件。     

The reconstruction and interpretations of lake status at 6 ka and 18 ka B.P.in inland mainland Asia

By means of survey of literature through compilations of sedimentological, biogeological and geomorphologic data, the inland lake level changes in arid or semi-arid mainland Asia at 6 and 18 ka B. P. have been reconstructed. The results showed that the lakes from western and northwestern Asia were characterized by very high water levels at 18 ka B. P., but low or intermediate water stands at 6 ka B. P. The high lake level in this region was associated with the southward displacement of westerlies, therefore, the extent of the high lake stand indicated the southern flank of westerlies during the glaciation. Conversely, the lakes from the eastern and southern Asia registered comparative low levels at 18 ka B. P. and significantly high one at 6 ka B. P. The lowering of lake level at 18 ka B. P. was caused by the weakened summer monsoon and the high lake level at 6 ka B. P. by the enhanced summer monsoon induced by the enlarged thermal contrast between land and ocean. The extent of high lake levels indicated the northern boundary of monsoon expansion. Between the above two regions, there is a climatic transitional zone in the Central Asia where the lake behavior was close to that in southeastern Asia at 6 ka B. P. but became similar to that in northwestern Asia at 18 ka B. P. Thus this zone became a transitional sector from the monsoon to the westerlies.     

Double-stream-pouring technique for production of gradient materials by continuous casting

A novel method for producing gradient materials by continuous casting is introduced. By using many-stream-pouring technique, samples with gradient distribution of alloy composition along the cross section have been prepared. The main difference of this method from the conventional continuous casting is the pouring system equipped with two sets of tundishes for liquid metals of different alloy compositions. Special consideration is given to the promotion and control of the crass-sectional mass transport. The steady heat transfer and mass flow ensure a partial mixing of two metals and yield a continously varying composition distribution. By adjusting the processing parameters, composition profile with different shapes can be achieved. First experiments have been carried out in Al-Si system and Al-Cu system for three series of Al/AlSi, AlSi/Al and AlCu/Al. It is shown that the alloy composition, the microntructure and the mechanical property change smoothly from the centre to the surface of the samples. This simple and practical method is potential for mass prodution of “structural gradient materials” and may offer a new way for alloy design.     

3DS软件分析

３ＤＳ是当前国内外十分流行的动画制作工具．特别是其３．０及其以上的版本能在微机的硬件环境下实现工作站一级硬件环境才能产生的动画效果,融计算机辅助设计与多媒体技术于一体,以其强大的功能蜚声中外．本文将介绍３ＤＳ的主要功能,并与ＡｕｔｏＣＡＤ相关内容进行分析比较．     

珊瑚礁坪地形上波生流的流场特性分析

将珊瑚礁坪地形简化为向海坡为1∶1的陡坡,基于SPH方法,建立了波浪在珊瑚礁坪地形上传播的数值波浪水槽,模拟规则波浪在珊瑚礁坪地形上的传播变化过程,分析珊瑚礁坪附近的流场特性,并将数值模拟结果与实验室观测结果进行对比。结果表明,在波浪传播过程中由于水深变浅,波浪发生变形和破碎,在珊瑚礁坪顶周围的水体中将产生一个与波浪传播方向相同的流动。