Sol–gel derived polycrystalline Cr1.8Ti0.2O3 thick films for alcohols sensing application

The powder sample of Cr_1.8Ti_0.2O₃ (CTO) was obtained by a sol–gel method. The thick films were developed on identical ceramic tubes of 4 mm length comprising of two Au-electrodes and printing an eight-layer film prepared by mixing CTO with glass powder and -terpinol as an organic vehicle. X-ray powder diffraction (XRD) patterns showed the formation of a single phase. The scanning electron microscope (SEM) images of the ceramic sensor treated at 850 °C revealed that the grain size was larger than 400 nm for the individual isolated grains on the surface, and the agglomerated dense spheroidal platelets had the size of 1–4 μm in diameter. The AC impedance measurement in ambient air showed that the resistance decreased nearly by two orders of magnitude with an increase in temperature in the range of 400–600 °C for both the powder sample and the thick film, and the activation energy E_a derived from the measurement was found to be 0.35 and 0.36 eV for the powder and the film, respectively. The films were exposed to various concentrations of alcohols (0.4–1.2 ppm of methanol and 1.0–5.0 ppm of ethanol), followed by determination of sensor response, sensitivity and reversibility and reproducibility. The origin of the gas response was attributed to the surface reaction of R-OH (R = methyl and ethyl group) with O⁻_(ads) to form adsorbed R-CHO, which was desorbed as a gas at 400 °C after the sensor departing from the gas.     

一种可关断晶闸管(GTO)直接门极驱动电路的研究

可关断晶闸管(GTO)要求其驱动电路提供的驱动电流的前沿应有足够的幅值和陡度,且一般需要在整个导通期间施加正门极电流,关断需施加负门极电流,幅值和陡度要求更高.主要结合GTO门极驱动的要求,提出一种新型的直接门极驱动电路,这种新型门极驱动电路结构简单,电感值低,因此可以为GTO提供快速的门极脉冲.每个GTO门板驱动完全独立,一定数量的GTO就可以串联使用来适应高压需要.     

Elasto-viscoplastic consistent tangent operator concept-based implicit boundary element methods

An elasto-viscoplastic consistent tangent operator (CTO) concept-based implicit algorithm for nonlinear boundary element methods is presented. Both kinematic and isotropic strain hardening are considered. The elasto-viscoplastic radial return algorithm (RRA) and the elasto-viscoplastic CTO and its related scheme are developed. In addition, the limit cases (e.g. elastoplastic problem) of vis-coplastic RRA and CTO are discussed. Finally, numerical examples, which are compared with the latest FEM results of Ibrahimbegovic et al. and ABAQUS results, are provided.     

以交换网络为中心的并行PC系统结构的可扩展性研究

针对传统的PCI总线结构形成系统通信瓶颈的缺陷，提出了以交换网络为中心的可扩展并行PC体系结构设计思想，对该体系结构的交换网络的可扩展性，如并行PC交换网络的管理模型网络寻址与路由以及系统内部通讯协议设计进行了深入研究，提出了相应的设计方案。     

并行PC：一种以交换网络为中心的新型PC体系结构设计

本文采用面向对象的系统设计方法对PC体系结构进行分析,针对传统PC的总线结构形成系统通信瓶颈的缺陷,提出了以交换网络为中心的并行PC体系结构设计思想,并对该体系结构各硬件对象,包括通信端对象（CTO）和通信载体对象（CCO）的结构设计,以及系统内部通讯协议和CTO对象功能交互模型提出了相应的设计方案。     

硫酸盐浆厂粗塔罗油精制方案探讨

扼要介绍了硫酸盐松木制浆厂的副产品－粗塔罗油的组成,用途及精制方案,并着重对各种精制工艺方案进行对比,供决策时选择。     

CTO外部社会资本、CTO-CEO信任关系与CTO技术战略决策影响力关系研究

以中国高科技民营企业为研究对象,通过问卷调研考察了企业CTO个人外部社会资本与其技术战略决策影响力的关系,并探索了CTO与CEO的人际信任关系对该作用过程的影响.多元回归结果表明,CTO外部社会资本结构维、CTO-CEO信任关系与CTO技术战略决策影响力正相关;CTO-CEO信任关系对CTO外部社会资本关系维、认知维与CTO技术战略决策影响力之间的关系具有调节作用.表明CTO必须充分建立外部社会资本,并与CEO保持良好的人际信任关系,才能更好地在技术战略决策中发挥作用.     

The effect of Ca-rich on the electric properties of Ca1+xCu3−xTi4O12 polycrystalline system

Ca_1+xCu_3−xTi₄O₁₂ (x = 0, 0.25, 0.5, 1) ceramics were prepared using the conventional solid-state reaction method. The XRD patterns show that Ca_1+xCu_3−xTi₄O₁₂ compounds are comprised of CaCu₃Ti₄O₁₂ (CCTO) and CaTiO₃ (CTO) phases compared with the traditional CCTO and the content of CTO phase increases with the increase of x. The micrographs demonstrate that the sample for x = 0 has larger grain size 8-10 μm. However, for the samples (x = 0.25, 0.5, 1), the mean grain size decreases markedly with the increase of CTO phase. The measurement for electric properties indicates that the permittivity values decrease with the increase of Ca atoms, but the breakdown electric field E_b and the nonlinear coefficient α values have a behavior reverse to it. The nonlinear coefficient α reaches 28 for x = 1, yet it is only 11.4 for x = 0 in the current range of 1-10 mA. This can be ascribed to the reduction of grain size and the changes in the electric conductivity of main grains and grain boundary with increasing Ca/Cu ratio. Imbalances between Ca and Cu atoms with Ca in excess can favor the non-ohmic properties in detriment to the dielectric property and a suitable Ca/Cu ratio can be selected to adjust the permittivity and I-V nonlinearity, according to different desired device applications.     

高通任命Matt Grob担任CTO

美国高通公司近日宣布,任命Matt Grob担任执行副总裁兼CTO。高通称,Grob将负责管理高通公司的技术路径,协调整个公司范围内的研发项目,推进下一代无线技术的开发,并且面向外部公众和合作高校,阐述公司的技术和发展方向。他还将继续领导高通公司的研发业务部门,并指导高通企业工程服务集团的工作。     

基于滑模变结构的复杂温度对象控制研究

针对一类复杂温度对象（CTO）进行滑模变结构控制算法的研究和实现。文中由浅入深地对控制对象本身、加干扰的对象和变参数的对象分别进行研究。通过仿真,得出VSS控制复杂温度对象的特点和可行性。结果表明：与传统的PID控制相比,滑模变结构控制在动、静态特性上均优于PID控制,尤其是它的动态快速性更占显著的优越性。此外,实现了无差控制且系统具有一定的鲁棒性。