丙烷-异丁烷体系的稳态精馏模拟和节能优化

首先对丙烷和异丁烷的精馏分离使用Fensake公式和Underwood公式分别确定理论级数和最小回流比,并与使用Aspen Plus中的DISTWU模块计算出的数值进行比较。在此基础上,文章将使用Distl模块,利用灵敏度等分析工具通过确定塔底塔顶的产物摩尔分率以寻找到合适的馏出物和回流比,并对最佳的进料位置,精馏塔的塔径进行优化模拟。最后,还从节能的角度对丙烷-异丁烷分离精馏塔进行经济优化。模拟所得结果,可为精馏塔设计及工业生产提供参考依据。     

Mesoporous polyaniline or polypyrrole/anatase TiO2 nanocomposite as anode materials for lithium-ion batteries

A functional composite as anode materials for lithium-ion batteries, which contains highly dispersed TiO₂ nanocrystals in polyaniline matrix and well-defined mesopores, is fabricated by employing a novel one-step approach. The as-prepared mesoporous polyaniline/anatase TiO₂ nanocomposite has a high specific surface area of 224 m² g⁻¹ and a predominant pore size of 3.6 nm. The electrochemical performance of the as-prepared composite as anode material is investigated by cyclic voltammograms and galvanostatic method. The results demonstrate that the polyaniline/anatase nanocomposite provides larger initial discharge capacity of 233 mAh g⁻¹ and good cycle stability at the high current density of 2000 mA g⁻¹. After 70th cycles, the discharge capacity is maintained at 140 mAh g⁻¹. The excellent electrochemical performance of the polyaniline/TiO₂ nanocomposite is mainly attributed to its special structure. Furthermore, it is accessible to extend the novel strategy to other polymer/TiO₂ composites, and the mesoporous polypyrrole/anatase TiO₂ is also successfully fabricated.     

高密度封装IC的高加速应力试验研究

采用在线监测技术对高密度封装IC样品进行温度步进试验、温度循环试验和振动步进试验等高加速应力试验,确定了产品的耐受应力极限,验证了本试验方案和试验监测技术的有效性和可行性。通过失效分析,确定了高加速应力下电路的失效模式和失效机理。结果表明:高密度塑封IC元件在高加速温循应力下比在随机振动应力下失效更为集中,温循试验在-65~165℃温度范围内,失效显著且集中在3个循环以内,主要包括塑封料和引线框架、基板的分层以及内键合点脱离,样品耐受随机振动量级超过50grms。研究结果可为器件级高加速应力试验研究提供参考。     

A 2.1-6 GHz SiGe BiCMOS low-noise amplifier design for a multi-mode wideband receiver

正A wideband low-noise amplifier(LNA) with ESD protection for a multi-mode receiver is presented.The LNA is fabricated in a 0.18-μm SiGe BiCMOS process,covering the 2.1 to 6 GHz frequency band.After optimized noise modeling and circuit design,the measured results show that the LNA has a 12 dB gain over the entire bandwidth, the input third intercept point(IIP3) is -8 dBm at 6 GHz,and the noise figure is from 2.3 to 3.8 dB in the operating band.The overall power consumption is 8 mW at 2.5 V voltage supply.     

The Chitinolytic Activities of Streptomyces sp. TH-11

Chitin is an abundant biopolymer composed of units of N-acetyl-D-glucosamine linked by β-1,4 glycosidic bonds. Chitin is the main component of the shells of mollusks, the cell wall of fungi and yeast and of the exoskeleton of crustaceans and insects. The degradation of chitin is catalyzed by chitinases that occur in a wide range of organisms. Among them, the chitinases from microorganisms are extremely important for the degradation and recycling of the carbon and nitrogen trapped in the large amount of insoluble chitin in nature. Streptomyces sp. TH-11 was isolated from the sediment of the Tou-Chien River, Taiwan. The chitinolytic enzyme activities were detected using a rapid in-gel detection method from the cell-free preparation of the culture medium of TH-11. The chitinolytic enzyme activity during prolonged liquid culturing was also analyzed by direct measurement of the chitin consumption. Decomposition of the exoskeleton of shrimps was demonstrated using electron microscopy and atomic force microscopy.     

FH-UDS催化剂的工业应用与器外再生

介绍了FH-UDS催化剂在250万t/a柴油加氢装置上的首次工业应用和器外再生后的运转情况。自2006年8月投产至2009年11月装置平稳运转39个月,其间产品质量合格,达到了生产清洁柴油的目的,能耗较低。经过器外再生后的FH-UDS催化剂,活性恢复较好,依然能满足清洁柴油生产的要求,说明FH-UDS催化剂具有良好的再生性能。     

Design of high efficiency dual-mode buck DC-DC converter

A buck DC-DC switching regulator with high efficiency is implemented by automatically altering the modulation mode according to load current,and it can operate with an input range of 4.5 to 30 V.At light load current,the converter operates in skip mode.The converter enters PWM mode operation with increasing load current.It reduces the switching loss at light load and standby state,which results in prolonging battery lifetime and stand-by time.Meanwhile, externally adjustable soft-start minimizes the inru...     

高原隧道工程机械尾气排放现场测试研究

高原隧道工程机械尾气排放CO和烟雾的现场测试对隧道通风系统设计及隧道施工所需的挖掘机、装载机和自卸汽车数量的匹配有重要的工程价值。以西格线中国铁路第一长隧——关角隧道为依托,进行了多种挖掘机、装载机和自卸汽车CO与烟雾尾气排放的现场测试,测试结果为铁路、公路隧道施工规范中"海拔高度修正系数"在3600～3800m的范围内取值提供依据和参考,对我国在高原地区修建隧道有一定的参考作用。     

Heat transfer and thermal storage behaviour of gypsum boards incorporating micro-encapsulated PCM

In the application of energy storage and thermal environmental control, PCM (Phase Change Material) is a very promising material choice. This study incorporated mPCM (micro-encapsulated PCM) into gypsum to make mPCM gypsum board and then investigated the physical properties, heat transfer and thermal storage behaviour. The major control parameters are wall temperatures and the weight percentages of mPCM added to the gypsum boards. A melting fraction correlation, reduced from our test data and based on Stefan number (Ste), subcooling (Sb) and Fourier number, is proposed. It shows that case with a higher Ste or Sb can have a higher heat transfer through the hot wall. Thermal storage behaviour of mPCM gypsum boards is then analyzed.     

城市规划实施效果评价研究综述

有关城市规划实施效果评价的研究一直被忽视,原因在于过去规划理论的研究多将重点放在如何制定规划而不是如何使用规划上,加上城市运作过程极为复杂,使人们很难将规划对城市发展的影响独立于其他影响因子之外加以检视,因此在现实中进行城市规划实施效果的评价难度极大。对此,Hopkins教授提出了四个评价规划是否产生作用的准则:效果、净利益、内在效度和外在效度,并构建了一个分析框架,从理论和概念上对城市规划的实施效果进行评价。此外,还可以通过计算器仿真及分析演绎,探讨规划对城市发展的影响。