Modulation Frequency Multiplexed Tunable Diode Laser Spectroscopy System for Simultaneous CO, CO2 Measurements

A modulation frequency multiplexed dual diode-laser system is developed for simultaneous detection of the two most common fire gas products CO and CO2. Simultaneous detection is achieved by modulating each laser at different frequencies, demodulating the signal by a pair of lock-in amplifiers for each gas. Laser beams are combined and detected by one detector after passing through an identical optical path. The experimental results show little performance degradation associated with modulation frequency multiplexing, and no cross-talk between the two multiplexed detection channels is measured.     

Dimensional Properties of Fractional Brownian Motion

Let B^α = {B^α（t）,t E R^N} be an （N,d）-fractional Brownian motion with Hurst index α∈ （0, 1）. By applying the strong local nondeterminism of B^α, we prove certain forms of uniform Hausdorff dimension results for the images of B^α when N 〉 αd. Our results extend those of Kaufman for one-dimensional Brownian motion.     

亚细胞器诱导的2,4,6-三硝基甲苯阴离子自由基的ESR研究

本文在无氧条件下利用ESR分别观察了肝脏和晶状体的微粒体及线粒体酶在NADPH存在下还原三硝基甲苯(TNT)的过程,检测到参数为g=2.0048±0.0005,A_对位~N=1.215mT,A~N=0.800±0.010mT,A~H=0.122±0.0206mT的自由基信号,并通过电子计算机对ESR谱的模拟证明该自由基信号为TNT硝基阴离子自由基,根据其超精细分裂常数认为,其不配对电子的电子云密度主要分布在对位硝基上。     

8~#风机排气消声器的设计与应用

本文提出了大截面消声器的设计方法和步聚,并对大型消声器的制造技术及其应用效果进行了探讨.     

Cutting tool materials for high speed machining

High speed machining (HSM) is one of the emerging cutting processes, which is machining at a speed significantly higher than the speed commonly in use on the shop floor. In the last twenty years, high speed machining has received great attentions as a technological solution for high productivity in manufacturing. This article reviews the developments of tool materials in high speed machining operations, and the properties, applications and prospective developments of tool materials in HSM are also presented.     

《雷雨》与祈雨仪式--曹禺剧作《雷雨》的文化学阐释

曹禺的《雷雨》之所以具有经久不衰的文化魅力并深受作者自己的喜爱,一个未被人们发掘出来的原因是它再现了一个古老的原型——祈雨仪式。在无意识的驱使下,曹禺以现代话剧的形式把古老的祈雨仪式再现在人们面前,不仅让人们重温了祈雨仪式中蕴涵的人类文化精神,也为人们树立了一个在人生旅途中必须不断审视自我、拯救自我、完善自我的范例。     

Liquid-Liquid Equilibrium for 1-Butanol-Water-KF and 1-Butanol-Water-K2CO3 Systems

KF or K2CO3 was added into the 1-butanol-water system and two phases were formed： water-rich phase （water phase） and 1-butanol-rich phase （1-butanol phase）. The liquid liquid equilibrium （LLE） data for 1-butanol-water-KF and 1-butanol-water-K2CO3 systems were measured at 25℃ and showed that 1-butanol phase contained negligible salt and water phase contained negligible 1-butanol when the concentrations of KF and K2CO3 in the water phase were equal to or higher than 27.11% and 31.68% , respectively. Thus water could be separated efficiently from 1-butanol-water by adding KF or K2CO3 into the system. A theoretical calculation of LLE data was calculated by using the Pitzer theory to get water activity in the water phase, and by the models, such as the Wilson, NRTL or the UNIQUAC for the 1-butanol phase. For 1-hutanol-water-KF system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and Wilson equa tion, while for 1-butanol-water-K2CO3 system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and UNIQUAC eauation.     

图书馆网站的使用性能测试

随着互联网的快速发展，越来越多的图书馆在网上建立了自己的网站，因此如何设计网站，提高网站的使用性能也成为人们关注的问题。介绍了亚利桑那大学图书馆采用的几种网站使用性能测试方法。     

美国初中级教育中对自然科学教师的培养及职业标准

对自然科学教师的培养及职业标准的研究是当代世界各国教育改革的焦点之一。本文试就美国对初中级教育中对自然科学教师的职业准备及其培养标准加以介绍和描述,特别是对美国七十年代以来对自然科学教育由重视到不重视再到重视的具体过程分析,以此为我国自然科学教师的培养提供借鉴作用。