船用柴油机NOx等有害排放气体的评价及处理研究--燃料喷射系统对乳化燃料在船用柴油机上使用的影响及脱硝装置的适用性

对原试验用柴油机的燃料喷射系统进行了改造。改造后的燃料喷射系统不仅可降低 NOx 的排放 ,而且使高加水率乳化燃料的使用成为可能。但另一方面 ,在低负荷时 ,使用乳化燃料不但不能获得预期的降低 NOx 排放效果 ,反而使其它有害排放增加。所以 ,也对降低 NOx 排放方法之一的脱硝装置进行了探讨 ,对其在船用柴油机上的适用性进行了试验 ,并获得了较好的效果     

The Employment of Reason

Rationalism in the Netherlands is characterised by pragmatism. As Charles Rattray explains it is a practical bent that was driven in the 20th century by the exigencies of building cheaply and quickly a large amount of social housing on a relatively small amount of land. It is a strand that has been underscored by a belief in reason across time and a confidence in an analytical approach. Copyright © 2007 John Wiley & Sons, Ltd.     

Prefabricating Memory Lane: Whatever Happened to Systems?

Three decades after his first involvement with an issue of 4 on systems buildings, John McKean, Professor of Architecture at the University of Brighton, revisits the subject. He concludes that, despite the ensuing years, architects still have much to learn about the mass production of buildings.     

智能插入式电磁流量计的研制

智能插入式电磁流量计是一种应用法拉第电磁感应定律的流量计。在电磁式流量计的基础上进行了创新,依据“拓普变换”原理对传感器进行创新设计。将传统双电极结构变换为单电极结构,把另一个电极作为虚拟电极对待,传感器的结构采用单电极,并将线圈分置于电极两边,控制磁力线分布趋势,从而实现高稳定、可靠、高精度的测量,同时使传感器密封空间得到扩展。     

钢铁的X射线荧光分析中三个修正模式的关系

钢铁试样的X射线荧光分析中,常应用莱琴斯(Lachance),德扬(De-jongh)及JIS(日本工业标准)3个修正模式修正基体效应。3个修正模式所用的修正系数存在一定的关系。本文认为莱琴斯模式及德扬模式的α系数可以相互转换,并由莱琴斯及德扬模式的α可以换算得到JIS模的d系数。
由莱斯琴模式中使用的理论修正系数计算得的E₁值与由校准曲线求得的值相同,而且,由莱琴斯模式的α系数换算得到的德扬模式、JIS模式的系数d与用个别三元法直接求得的系数也是相同的。     

Production of porous SiC by liquid phase sintering using graphite as sacrificial phase: Influence of SiO2 and graphite on the sintering mechanisms

Porous silicon carbide (SiC) is a promising ceramic for high-temperature applications due to its unique combination of properties. In the present work, a fabrication route for porous SiC is presented using graphite spherical powder as sacrificial phase to introduce porosity. By varying the initial amount of sacrificial phase, high-performance SiC materials with porosities in the range 30–50% were manufactured and characterized in terms of microstructure, density, thermal conductivity and flexural strength. The materials were fabricated by liquid phase sintering in presence of 2.5 wt.% Al₂O₃ and Y₂O₃ as sintering additives. The results indicate that the SiO₂ present in the starting SiC powders interacts with the sintering additives forming liquid phases that promote densification and weight loss. Besides, an Al-Si liquid phase is formed at higher sintering temperatures, whose contribution to densification is inhibited in presence of graphite due to the formation of Al-rich carbides.     

Optimization of sub-0.1-μm offset Γ-shaped gate MHEMTs for millimeter-wave applications

We examine the effects of device scaling in both vertical and lateral dimensions for the metamorphic high electron mobility transistors (MHEMTs) on the DC and millimeter-wave electrical performances by using a hydrodynamic transport model. The well-calibrated hydrodynamic simulation for the sub-0.1-μm offset Γ-gate In_0.53Ga_0.47As/In_0.52Al_0.48As MHEMTs shows a reasonable agreement with the electrical characteristics measured from the fabricated 0.1 μm devices. We have calibrated all the parameters using the measurement data with various physical considerations to take into account the sophisticated carrier transport physics in sub-0.1-μm devices. Being simulated with these calibrated parameters, the optimum device performance is obtained at a source-drain spacing of 2 μm, a gate length of 0.05 μm, a barrier thickness of 10 nm and a channel thickness of 12 nm.     

多泥沙泵站改造设计中应注意的几个问题

本文结合工程实例，分析了泥沙时泵站运行的不利影响，提出了减少泥沙危害的几种工程措施，对多泥沙泵站的改造设计有一定的借鉴作用。     

复旦大学4MV质子静电加速器

一、前言复旦大学加速器实验室自行设计改建的4MV质子静电加速器。自1979年9月安装调试出束后进行了一些性能试验。加速器空载电压(无加速管)超过5MV,有加速管空载、最高试验电压为3.5MV,加速的质子最高能量为3.2MeV。束流脉冲化工作,