Advances in titanium metal injection molding

The approaches to production of titanium powder injection molded parts are reviewed. Historically, oxygen levels have been too high for structural use (particularly with the Ti-6Al-4V alloy). However, recent advances in starting powders, binders and sintering facilities now allow oxygen levels in the Ti-6Al-4V alloy to be controlled to about 0.2 wt.% oxygen. This should result in significant expansion of the titanium PIM market place into aerospace, automobiles, surgical instruments, dentistry, communication devices (such as computers and cell phones), knives and guns. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 5–6 (455), pp. 118–125, 2007.     

基于IPv6校园网的智能选课系统的J2EE架构的设计与实现

通过分析IPv6校园网自主学习模式下的自主选课问题,提出了利用J2EE技术构建基于IPv6校园网的智能选课系统的总体结构及具体实现.     

Single and combined deactivating effect of alkali metals and HCl on commercial SCR catalysts

Two commercial SCR catalysts, with a nominal W content of about 9 wt.% and a V nominal content of 0.55 and 1.8 wt.%, respectively, were contacted with different amounts of Na and K and with HCl vapours in order to simulate poisoning by species more specifically contained in exhaust gases from MSW combustion. Catalysts were characterised using XRD analysis, SEM/EDX analysis, BET and pore size distribution measurements, NH₃ TPD, TG analysis. Poisoning agents do not cause loss of surface area nor pore occlusion. A significant loss of surface acidity was observed upon alkali metals poisoning whereas a decreasing of vanadium content was observed for the more concentrated catalysts upon HCl poisoning. Catalysts deactivation is proportional to the number of acid sites neutralised by alkali metals adsorbing ammonia in the temperature range typical of SCR process. HCl promotes the formation of new acid sites showing a lower activity compared to the original one.     

首钢6H3C单机架可逆式薄板冷轧机组技术特点

首钢6H3C单机架可逆式冷轧机组是目前世界上第一套通过中间辊交叉进行板型控制的轧机．也是世界上第一套投入工业生产的6H3C轧机。本文介绍了该机组的工艺、设备参数，技术特点，电气设备及自动化控制及生产状况，并提出了该机组可能存在的问题。     

浅谈下一代网络（NGN）

计算机网络的发展日新月异。下一代计算机网络（NGN）的探讨、研究已经成为当前的潮流。下一代网络是目前电信、互联网运营商和设备厂商都在讨论的热点技术，国内外许多网络运营商都在探讨，并正在或考虑建设试验网进行更深入的研究。本文介绍了NGN的定义、主要特点、分层结构和关键技术。     

两步法合成2-氨基-5-硝基苯酚

以邻氨基苯酚和尿素为原料,将传统环合-硝化-水解三步法工艺改为环合硝化-水解两步法合成了2-氨基-5-硝基苯酚(ANP);研究了影响环合硝化反应和水解反应的因素;优化了反应条件。环合硝化反应的最优条件为:n(邻氨基苯酚)∶n(尿素)=1.00∶1.20、环合时间6h、硝酸用量40.2g、硫酸用量20g、硝化时间3h、硝化温度70℃,在此条件下中间产物6-硝基苯并噁唑酮的收率为90.2%;水解反应的最优条件为:体积分数95%的乙醇为溶剂、n(6-硝基苯并噁唑酮)∶n(氢氧化钠)=1.0∶3.3、水解温度80℃、水解时间15h,在此条件下ANP收率为81.2%。两步反应ANP的总收率为73.2%。对产品进行了元素分析和红外光谱表征,确认终产物为ANP。该方法成本低,ANP总收率高,溶剂可回收,三废量少。     

Characteristics and classification of high-current fault arcs on distribution systems

When a fault occurs on transmission or distribution systems due to lightning or overvoltage, often an arc discharge occurs at the fault point. The arc discharge, which is caused by a fault current, has a high current, high temperature, strong light emission, etc., thus it sometimes causes heavy damages to electric power equipment. The arc discharge is influenced by the conditions around the arcs, i.e., gas, insulation materials, gap length, weather, etc. Also, the arc voltage along the arc column indicates the characteristics of the arc. If the voltage waveforms of the arcs caused by the fault on transmission or distribution systems are classified, it is possible to find the location and the equipment where the fault occurred. In this paper, the arc voltage data in 6-kV class XLPE cables and 6-kV class overhead lines are analyzed and an artificial neural network method is applied to classify the arc voltage waveforms. The results obtained from the six artificial neural networks developed show that the artificial neural network method is effective for classification of arc voltage waveforms if adequate input parameters are selected.     

HDPE／PA6共混型塑料阻隔材料

以自制接枝聚乙烯为增容剂，高密度聚乙烯为基材，尼龙６为阻隔材料，用挤出法，制取ＨＤＰＥ／ＰＡ６共混材料。ＭＰＥ的加入，增大了相间的粘接改善了力学性能，使材料具有良好的阻渗性能。