碳纳米管及其批量制备研究进展

从碳纳米管的优异性能和应用出发,综述了碳纳米管的制备方法以及我国目前在碳纳米管研究中面临的问题;分析了碳纳米管产业化对的我国纳米技术产业化发展的积极意义,特别介绍了清华-南风纳米粉体产业化工程中心开发的、具有我国自主知识产权的纳米聚团流态化技术。     

部分预应力框架梁柱节点在反复荷载下的受力性能

本文通过8个梁柱节点组合体在低周反复荷载作用下的试验,考察了预应力对节点强度、刚度和能量耗散能力的影响,研究了梁筋的粘结滑移问题。根据试验结果,提出了节点抗剪强度和梁筋锚固等设计建议。     

稠油出砂冷采过程中储层孔隙度预测模型

从岩石力学原理出发，结合稠油出砂冷采过程中的动态特征，研究了等温条件下疏松砂岩体积应变率随累积产油量和累积出砂量的变化规律，建立了出砂冷采过程中储层孔隙度的预测模型。该模型可以定量预测稠油出砂冷采过程中储层孔隙度的变化规律，从而为出砂冷采过程中其他规律的研究奠定了基础。     

Optimum Design for RF-to-Optical Up-Converter in Coherent Optical OFDM Systems

In this letter, we conduct analysis on the optimum design for RF-to-optical up-converter in coherent optical OFDM systems using an optical I/Q modulator. We first derive closed-form expressions for the nonlinearity in the optical I/Q modulator, represented by two-tone intermodulation products as a function of the bias point and modulation index. Additionally, we perform a numerical simulation to identify Q-penalty and the excess modulation insertion loss under various transmitter conditions. We find that in contrast to the direct-detected system, the optimal modulator bias point for the coherent system is pi, where the Q-penalty and excess loss are minimized     

炼钢中间包塞棒液压伺服比例控制系统的应用

济钢第三炼钢厂中间包塞棒液压伺服比例控制系统采用伺服比例阀和伺服缸等,系统设计完善,功能齐全,可实现塞棒位置的闭环控制,保证了结晶器中钢水液面的稳定。     

An alternative method to compute the component fractions in the geometrical optical model: visual computing method

A method called visual computing was used to solve angular four-components' proportions and directional vegetation cover fraction for discrete canopies and continuous row-planted plants. It proved effective to predict the angular characteristics on pixel scale. The method could be an alternative way to a classical solution of geometrical optical models. A visual computing method would be effective especially when the canopies' spatial distribution and shapes were irregular and could not be described statistically.     

A broadband PHEMT MMIC distributed doubler using high-pass drain line topology

A broadband frequency doubler, based on distributed amplifier techniques, has been designed to operate from 11 to 21 GHz. In order to reject the fundamental signal over a broadband frequency range, the conventional low-pass drain line structure was replaced with the high-pass structure. This topology can suppress fundamental signals over broadband without any balanced structure so that the chip size can be more compact. Measured conversion losses of better than 10 dB from 11 to 21 GHz input frequencies are achieved with fundamental signal rejection better than 12 dB. To the best of our knowledge, this is the first demonstration of distributed doubler using the high-pass drain line topology.     

PBA/PMMA核壳结构乳胶粒子粒径分析

采用种子乳液聚合制备出了PBA/PMMA核壳结构乳胶粒子，研究并分析了MMA在3种不同投料方式（间歇法、半间歇法和平衡溶胀法）下粒子粒径变化情况。实验发现第二单体采用间歇法投料可获得较理想的核壳结构乳胶粒。     

Selective hydrogenation of oleic acid to 9-octadecen-1-ol: Catalyst preparation and optimum reaction conditions

A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-1-ol (oleyl + elaidyl alcohol) at low pressure with high yield. Catalyst preparation methods, catalyst raw materials and activation conditions have a significant effect on the activity of the catalyst. The optimum atomic ratio of ruthenium to tin is about 1:2. Catalyst prepared by an improved sol-gel method shows higher activity and selectivity than catalysts prepared by impregnation and coprecipitation methods. Chloride is found to have a negative effect on catalytic activity. The best catalyst is prepared from chloride-free ruthenium and tin raw materials. Under the optimum reaction conditions of 250°C and 5.6 MPa, the selectivities for 9-octadecen-1-ol and total alcohol (9-octadecen-1-ol + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%.