Numerical simulations of draw resonance in melt spinning of polymer fluids

This article deals with numerical simulations of draw resonance of polymer fluids by employing direct difference methods to solving the governing equations in melt spinning. The stability of each difference method was studied by a comparison of the results obtained from simulations with the theoretical solutions or values. The numerical simulation confirms that the critical draw ratio of draw resonance in an isothermal and uniform tension spinning of a Newtonian fluid is between 20 and 21. The cross-sectional area of a spinline in draw resonance was found to decrease monotonically from a spinneret toward a take-up bobbin, although the taken-up filament shows periodical variation. This study has also illustrated the mechanism of draw resonance previously proposed by the author. © 1993 John Wiley & Sons, Inc.     

Experimental measurement of gas concentration distribution in an impinging entrained-flow gasifier

On a laboratory-scale testing platform of impinging entrained-flow gasifier with two opposed burners, the detailed measurements of gas concentration distribution have been performed for carbonaceous compound (diesel oil) at atmospheric pressure. Under the condition of 1.48–2.36 O/C ratios (kg/kg), radial gas samples are collected at three axial positions and the syngas exit position with stainless steel water-cooled probes, the concentration distribution of the major gases (H₂, CO, CO₂, CH₄ and O₂) under stable operating state was determined with a mass spectrometry. These data are used to clarify mixing and reaction characteristics within the reactor, to give insight into the combustion process and provide a database for evaluating predictive mathematical models.     

萨尔马法在大广坝抗震稳定分析中的应用

本文用萨尔马法和我国抗震规范法两种方法，分析了大广坝土坝抗震稳定性，萨尔马法可算出临界加速度，不能直接算出安全系数，本文进一步发展，可算出安全系数，并与抗震规范法算出的结果作了对比，经过大量的计算，发现了萨尔马法所存在的某些局限性，并对其原因进行了初步探讨，对改进的抗震规范法提出了实施的办法，以考虑地震孔隙水压力升高强度降低的影响。     

开展超多道数字地震仪的应用研究

地震记录仪器由20年代的1道发展到80年代初的1000多道,60年来增加了1000倍。道数的增长趋势是直线性的,40年代出现24道仪器,50年代出现48道仪器,60年代末出现96道仪器,基本上是十年翻一番,而70年代则由96道增加到192、240乃至384道,翻了不止一番,80年代初的三年中仪器道数已由384而至576乃至1024道,最近舍赛尔公司又推出了号称万道的仪器。因此,近年来地震仪的道数增加的势头不仅不衰,似乎更快     

中国北方中生界石油超体系

依据中国北方中生代含油气盆地的特征和演化，划分了中国北方中生界石油超体系。中国北方区域在中生代经历了三大区域构造演化阶段，在此背景下，区域古气候条件的变迁在很大程度上控制了中生代沉积体系发育和生烃物质的富集程度，形成由多个岩体构成的区域性生、储、聚油气层系，大体可分为中－上三叠统石油超体系、株罗系石油超体系和白垩系石油超体系，其中白垩系还可分为干旱区下白垩统石油体系和潮湿区下白垩统石油体系及上白垩     

Rapid chemical kinetic techniques for investigations of neurotransmitter receptors expressed in Xenopus oocytes

Xenopus laevis oocytes have been used extensively during the past decade to express and study neurotransmitter receptors of various origins and subunit composition and also to express and study receptors altered by site-specific mutations. Interpretations of the effects of structural differences on receptor mechanisms were, however, hampered by a lack of rapid chemical reaction techniques suitable for use with oocytes. Here we describe flow and photolysis techniques, with 2-ms and 100-microseconds time resolution, respectively, for studying neurotransmitter receptors in giant (approximately 20-microns diameter) patches of oocyte membranes, using muscle and neuronal acetylcholine receptors as examples. With these techniques, we find that the muscle receptor in BC3H1 cells and the same receptor expressed in oocytes have comparable kinetic properties. This finding is in contrast to previous studies and raises questions regarding the interpretations of the many studies of receptors expressed in oocytes in which an insufficient time resolution was available. The results obtained indicate that the rapid reaction techniques described here, in conjunction with the oocyte expression system, will be useful in answering many outstanding questions regarding the structure and function of diverse neurotransmitter receptors.     

SrTiO3陶瓷中掺杂和Ti／Sr比的配合

在ＳｒＴｉＯ３双功能陶瓷的制备中，最关键的是晶粒生长、晶粒半导化和晶界绝缘化。ＳｒＴｉＯ３晶粒生长和半导化受到多种因素的影响，诸如杂质的各类和含量、Ｔｉ／Ｓｒ比、烧结温度、氧分压等，这些因素是相互制约、共同作用的。研究表明，适当的Ｔｉ过量促进晶粒生长；Ｔｉ／Ｓｒ≈１时，可降低数烧结对氧分压的要求；过量Ｔｉ＾４＋和Ｓｒ＾２＋的固溶限受到氧分压和施主掺杂的影响，与此类似，施主杂质Ｎｂ＾５＋和Ｌａ＾３＋