Materials and Wireless Microfluidic Systems for Electronics Capable of Chemical Dissolution on Demand

Electronics that are capable of destroying themselves, on demand and in a harmless way, might provide the ultimate form of data security. This paper presents materials and device architectures for triggered destruction of conventional microelectronic systems by means of microfluidic chemical etching of the constituent materials, including silicon, silicon dioxide, and metals (e.g., aluminum). Demonstrations in an array of home‐built metal‐oxide‐semiconductor field‐effect transistors that exploit ultrathin sheets of monocrystalline silicon and in radio‐frequency identification devices illustrate the utility of the approaches.     

分立拉曼放大器中的瞬态研究

研究了在有增益饱和的反向抽运光纤拉曼放大器 (FRA)中的瞬态现象 ,并通过解析表达式及数值分析发现瞬态持续时间可用信号在FRA光纤中的往返传播时间 (一般在 10 - 1 ms量级 )来表征。在级联FRA中功率瞬态会随着级数的增加而恶化。分析还表明在前向抽运的饱和FRA中 ,交叉增益饱和将导致信道串扰和消光比下降。最后讨论了如何设计增益箝制的FRA(GC FRA)以最大限度地抑制瞬态     

Transient analysis of a gas manifold system

In the present work, a numerical study has been carried out to predict transient gas flow and pressure behaviour in a gas manifold system. The start‐up and shutdown of the system, varying demands at the consumer ends, malfunctioning of compressors and valves are a few examples of common causes of transience in a gas delivery system. In particular, the sensitivity of oscillations in pressure and mass flux to variation in pipe dimensions, supply pressure and gas flow rate are ascertained under the aforementioned conditions of transience. The present results show that large pipe dimensions, high gas flow rate and high upstream pressure in the branch in which the disturbance is introduced, all cause greater amplitude in mass flux and pressure oscillations in the neighboring branches. The duration of oscillations is also found to be longer. The present study has practical importance in designing as well as in operating, a gas delivery system.     

品味中国艺术设计中的太极精神

中华先人以其独特的宇宙人生观,形成了影响深远的"太极说".中华传统艺术融"太极"精神、"阴阳五行学说"于一体,形成了丰厚的人文底蕴,以"虚实相生"的空灵意境美体现了对宇宙独特的东方体验.我国的艺术设计发展到今天,除了在技法上求发展以外,更注重对中华传统艺术精神的继承和创新.依托在太极精神的根基之上,把握好中国独特的东方意境之美,将使我们的艺术设计作品隽永长存.     

Architecture and Dispersal

To close the issue, guest-editors Rafi Segal and Els Verbakel curated a discussion with Stan Allen, Margaret Crawford, Marcel Smets and Sarah Whiting, and put some provocative questions to them: What constitutes public space in the contemporary city? Can the public sphere still exist in the urban context? Should public space be fought for by architects and urban designers? Or, as Allen proposes, is it the landscape architects alone who have been quick to realise the potential of the empty spaces in our cities as a ripe terrain for change? Copyright © 2008 John Wiley & Sons, Ltd.     

谐振接地系统全补偿下单相故障的特征分析

针对谐振接地系统在实际应用中个别情况下即使完全补偿仍会出现残流过大进而影响到电网的安全运行的现象,分析了其产生的机理,并通过数字仿真再现了该暂态过程。对谐振接地方式下单相接地故障暂态过电压特征也进行了ATP仿真,对如何降低故障暂态过电压提出了建议。     

Rd+上重自相似马氏过程的位势性质

借助于重自相似马氏过程的Lamperti表现,讨论R d-值的重自相似马氏过程的一些位势性质,给出了该过程常返与暂留性判定的一个充要条件,并给出了其(本性)极集判定的一个充要条件.     

单粗糙峰通过接触区全过程的时变热弹流数值仿真

建立了带单粗糙峰的表面滚滑工况的点接触时变热弹流模型，数值模拟了钢与钢接触、快速表面带单粗糙峰通过接触区的全过程。结果表明，接触区内的粗糙峰会引起局部高压，当粗糙峰较高时，润滑膜会变得极薄，这对润滑的可靠性是不利的，而局部压力高峰也会严重降低材料的表面疲劳寿命。