Numerical study on the restriction speed of train passing curved rail in cross wind

The results of numerical investigations of aerodynamic forces and moment coefficients of flow passing a simplified train geometry under different wind speeds are summarized. To compute numerically the different coefficients, the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations, combined with the k-ε turbulence model, were solved using finite volume technique. The pres-sure-velocity fields were coupled using the SIMPLE algorithm. At each iteration the pressure correction was obtained by sol...     

Experiments and reaction characteristics of liquid phase simultaneous removal of SO<Subscript>2</Subscript> and NO

Experiments of simultaneous removal of SO₂ and NO from simulated flue gas, using NaClO₂ solution as the absorbent, were carried out in a self-designed bubble reactor, and high simultaneous removal efficiencies of SO₂ and NO were obtained under the optimal experimental conditions. The mechanism of simultaneous removal based on NaClO₂ acid solutions was proposed by analyzing the removal products. Possibility and limitation of the desulfurization and denitrification using NaClO₂ acid solutions were calculated by thermodynamic methods. Experimental results of reaction kinetics for simultaneous desulfurization and denitrification indicated that the oxidation-absorption processes of SO₂ and NO were divided into two zones, namely the fast and slow reaction zones. In the slow reaction zones both were zero order reactions, and in the fast reaction zones, the reaction order, rate constant and activation energy of SO₂ reaction with absorbent were 1.4, 1.22 (mol·L⁻¹)^−0.4·s⁻¹ and 66.25 kJ·mol⁻¹, respectively, and 2, 3.15×10³ (mol·L⁻¹) ⁻¹·s⁻¹, and 42.50 kJ·mol⁻¹ for NO reaction, respectively. Supported by the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2007AA061803)     

Multi-channel micro neural probe fabricated with SOI

Silicon-on-insulator(SOI) substrate is widely used in micro-electro-mechanical systems(MEMS).With the buried oxide layer of SOI acting as an etching stop,silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability.A seven-record-site neural probe was formed by inductive-coupled plasma(ICP) dry etching of an SOI substrate.The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm2.The im...     

Hybrids perfluorosulfonic acid ionomer and silicon oxide membrane for application in ion-exchange polymer-metal composite actuators

This paper reports a new technique to fabricate an ion-exchange polymer-metal composite (IPMC) actuator. This technique is based on a hybrid organic-inorganic composite membrane. In the fabrication course, silica oxide particles, prepared from hydrolysis of tetraethyl orthosilicate in situ with sol-gel reaction, co-crystallize with perfluorosulfonate acid (PFSA) ionomer. Attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) analyses demonstrate that a highly water-saving hybrid mem...     

Research on indoor experimentation of range SAL imaging system

By means of advantages of both SAR and lidar, the combination of the techniques of (inverse) synthetic aperture and lidar makes it possible to obtain high resolution 2-D image. In this paper, an indoor experimental system of inverse synthetic aperture lidar imaging is given and a processing approach is presented. The given system is in the mode of lidar system with separated receiver and transmitter, which can effectively eliminate the jamming from the lens or/and the intersection between two optic fibers. ...     

区域创新能力评价指标体系及实证

在考察国内外区域创新研究现状的基础上,给出了区域创新能力的概念及内容,设计了区域创新能力评价指标体系,并利用2007年的统计数据,围绕知识创造、知识流动、企业技术创新、技术创新环境和创新的经济绩效等5个方面,运用主成分和层次分析法对我国31个省市的创新能力进行了分析,东部省市的整体创新能力水平较高,东北和中部次之,西部较差.     

粉煤灰效应的模糊综合评价

我们从粉煤灰的具体特性出发,总结和吸取了人们长期积累的实践经验,建立了粉煤灰效应的模糊综合评价层次结构模型,构造了需水量比、强度比、颗粒形态等因素的隶属函数,采用层次分析法计算了各因素在粉煤灰效应模糊综合评价中的权重。最后应用模糊综合评价方法综合了各因素对粉煤灰效应的“贡献”程度,工程实例证明该方法可以有效地描述粉煤灰效应的评价结果。     

基于嵌入式多串口扩展的出租车智能导航终端设计与实现

目前,ARM处理器在嵌入式系统中得到了广泛的应用,但其通常只有3个及以下的串口,难以满足需要多串口设备的系统需求;分析研究基于ARM处理器的智能车载导航终端的多串口扩展问题,提出采用具有单串口扩展为5串口功能的串口扩展芯片GM8125,实现嵌入式系统的多串口扩展需求,并在串口通信中采用分层设计的方法,提高系统的稳定性和运行效率;该出租车智能移动导航终端系统经过实际调试与运行,能够实现预定功能且效果良好,能够应用到新型的智能交通调度系统中。     

Preparation and characterization of SO42-/TiO2 and S2O82-/TiO2 catalysts

Nanosized solid superacids SO₄ ²⁻/TiO₂ and S₂O₈ ²⁻/TiO₂, as well as MCM-41-supported SO₄ ²⁻/ZrO₂, were prepared. Their structures, acidities, and catalytic activities were investigated and compared using XRD, N₂ adsorption-desorption, and in situ FTIR-pyridine adsorption, as well as an evaluation reaction with pseudoionone cyclization. The results showed that SO₄ ²⁻/TiO₂ and S₂O₈ ²⁻/TiO₂ possess not only nanosized particles with diameters < 7.0 nm, a BET surface greater than 140 cm²/g and relatively regular mesostructures with pores around 4.0 nm, but also a pure anatase phase and strong acidity. Different from the Lewis acid nature of SO₄ ²⁻/ZrO₂/MCM-41, SO₄ ²⁻/TiO₂ and S₂O₈ ²⁻/TiO₂ exhibit mainly Bronsted acidities. The strongest Bronsted acid sites were produced on SO₄ ²⁻/TiO₂ promoted with H₂SO₄, while Lewis acid sites on S₂O₈ ²⁻/TiO₂ even stronger than those on SO₄ ²⁻/ZrO₂/MCM-41 were generated when persulfate solution was used as sulfating agent. Because of their distinct acid natures, SO₄ ²⁻/TiO₂ and S₂O₈ ²⁻/TiO₂ exhibited catalytic activities for the cyclization of pseudoionone that were much higher than that of SO₄ ²⁻/ZrO₂/MCM-41. It can be concluded that the existence of more Br?nsted acid sites was favorable for proton participation in the cyclization reaction. Translated from Journal of Chemical Engineering of Chinese Universities, 2006, 20(2): 239–244 [译自: 高校化学工程学报]     

基于α-叔碳-β,γ-不饱和醛的制备全合成番茄红素

将一种α-取代-α,β-不饱和醛的制备方法应用于番茄红素(Ⅵ)的全合成中,通过该法以廉价的原料假性紫罗兰酮(Ⅰ)制备了2,6,10-三甲基-3,5,9-十一烷三烯-1-醛(Ⅱ),然后与四乙基亚甲基二磷酸酯(Ⅲ)经过Wittig-Horner反应得到关键中间体3,7,11-三甲基-1,4,6,10-四烯十二烷基膦酸二乙酯(Ⅳ),最终和2,7-二甲基-2,4,6-辛三烯-1,8-二醛(Ⅴ)进行Wittig-Horner反应、转位异构合成全反式番茄红素。反应共经历3步线性反应,总产率为37.0%。最终产物的结构采用IR、HRMS和NMR进行确证。