蒸发时间对两级凝胶法制备的聚醚砜膜结构和性能的影响

主要探讨了蒸发时间对用两级凝胶法(dual—bath coagulation method)所制得的聚醚砜(PES)超滤膜的性能和结构的影响．结果表明，随着蒸发时间的延长，水通量先减小后增大；肌肝和尿素去除率均是先升高而后降低，然后再升高的趋势；膜的孔隙率上升，平均孔径下降．在蒸发时间为10s时，肌肝和尿素去除率最高，且水通量适中，是血液净化用聚醚砜膜的最佳成形条件．     

控制厚度分布的正反向超塑胀形的有限元分析

为研究正反向超塑胀形工艺对厚度分布的影响,应用商业有限元软件MARC对带有凹槽的深盒形7475合金零件正反向超塑胀形过程进行了有限元模拟,并对不同工艺条件下成形后零件的壁厚分布结果进行了分析.研究表明:正反向超塑胀形工艺是控制成形零件壁厚的有效途径,通过优化压力-时间曲线和反向胀形模具形状,明显改善了零件的厚度分布,达到了零件的设计要求;后处理直观地显示了该零件正反向超塑胀形的全过程,为成形提供了合理的方案;零件变形各阶段的应变速率控制在7475合金的应变速率范围内,证明压力-时间曲线设计合理.     

化学镀Ni-W-P-SiC复合镀层的性能研究

研究了化学镀Ni W P SiC复合镀层的性能。结果表明,该化学复合镀层在HCl、H2SO4、H3PO4和FeCl34种腐蚀介质中的耐蚀性优于1Cr18Ni9Ti不锈钢的,经600℃以下热处理的镀层的耐蚀性优于镀态镀层的,其中400℃热处理后镀层的耐蚀性最好。镀层硬度和耐磨性随温度的升高而升高,在400～600℃之间硬度和耐磨性都较高,加热温度继续升高,镀层硬度和耐磨性下降较快。在400℃热处理条件下,随着热处理时间的延长,镀层的硬度和耐磨性提高,当热处理时间达到3h时,镀层硬度和耐磨性最高,若继续延长时间,镀层的硬度和耐磨性又降低。     

会展建筑中的大空间排烟系统分析

通过对会展建筑中的大空间展厅的火灾情形、排烟量及排烟方式的分析,得出了一个适合此类建筑的排烟系统设计的经济合理的参考方案.     

Ti、La对贮氢合金ZrMn0.7 V0.2 Co0.1 Ni1.2相结构和电化学性能的影响

研究了贮氢电极合金Zr1-xTixMin0.7V0.2Co0.1Ni1.2的相结构和电化学性能。结果表明，随着掺Ti量的增加，该合金主相中C15型Laves相含量逐渐减少而C14型Laves相含量逐渐增加，同时非Laves相Zr7M10和TiNi相全部消失，说明元素Ti掺杂量的增加抑制了第二相的产生。当含Ti量x=0．2时，该合金具有最大放电容量Cmax为354mAh／g，在放电电流为300mAh／g条件下，高倍率放电性能比母体合金提高了15％。而对于合金Zr0.75Ti0.2La0.05Mn0.7V0.2Co0.1Ni1.2，其活化性能被大大提高，只需4次就能达到最大放电容量372mAh／g，而且经过30次循环仍能保持最大放电容量的93％。     

改善烧结料层透气性途径的探讨

介绍韶关冶炼厂烧结机烧结料层透气性的情况以及改造途径．     

长城特钢GCr15轧后控冷解决碳化物网状问题浅析

通过对Φ12-14mmGCr15盘元碳化物网状的理论探讨和研究，在生产过程中采用控制冷却的方式，达到控制碳化物的析出及网状级别的目的，最终解决长城特钢生产Φ12-14mmGCr15盘元网状的问题。     

Etching characteristics and mechanism of Pb(Zr,Ti)O3 thin films in CF4/Ar inductively coupled plasma

The effect of the CF₄/Ar mixing ratio on the etching behaviour and mechanisms for Pb(Zr,Ti)O₃ (PZT) thin films in an inductively coupled plasma was carried out. It was found that an increase of Ar mixing ratio causes non-monotonic behaviour of the PZT etch rate, which reaches a maximum of 2.38 nm/s at 80% Ar. Investigating the plasma parameters, we found a weak sensitivity of both electron temperature and electron density to the change of CF₄/Ar mixing ratio. A combination of zero-dimensional plasma model with the model of surface kinetics shows the possibility of a non-monotonic etch rate behaviour due to the concurrence of physical and chemical pathways in the ion-assisted chemical reaction.     

An improvement of the EDI method in linear elastic fracture mechanics by means of an a posteriori error estimator in G

In this paper, an error estimator that quantifies the effect of the finite element discretization error on the computation of the stress intensity factor in linear elastic fracture mechanics is presented. In order to obtain the proposed estimator, a shape design sensitivity analysis (SDSA) is applied to the fracture mechanics problem. Following this approach, one of the most efficient post‐processing techniques for computing the strain energy release rate G, the well‐known EDI method, may be interpreted as a continuum method of the SDSA. The proposed error estimator is based on the recovery of the gradient fields and its reliability has been checked by means of numerical problems, yielding very good estimations of the true error. The new estimator remarkably improves the results given by a previous error estimator, which is based on a discrete analytical approach of SDSA. As a consequence, the combination of the new error estimator and the result given by the EDI method provides a much more accurate estimation of G. Copyright © 2003 John Wiley & Sons, Ltd.