On the three-phase mass transfer with solid particles adhered to the gas-liquid interface

A heterogeneous, multi-layer mass transfer model is proposed for prediction of the effect of multi-layer packing of catalyst particles adhered to the gas-liquid interface. The behavior of the mass transfer rate with respect to the multi-layer packing, to the particle size and mass transfer coefficient without particles is discussed. It is shown that enhancement can be considerably increased by multi-layer packing compared to that of mono-layer packing, depending on the values of particle size and mass transfer coefficient. The predicted mass transfer rates using the proposed model was verified with experimental data taken from the literature. The model presented should be superior to that of published in the literature.     

计入孔隙结构影响的复层含油轴承润滑特性分析

基于Darcy定律和Kozeny-Carman孔隙方程,建立多孔质复层含油轴承的流体润滑模型,利用有限差分法数值模拟,分析复层结构和孔隙参数对含油轴承润滑性能的影响.得出结论如下:复层含油轴承润滑性能随轴承高度增大而变差,随孔隙率减小而变好,当总孔隙率一定时,较低的表层孔隙率有利于提高复层含油轴承润滑性能.因此设计复层含油轴承时,在保证一定孔隙含油量的前提下,应尽可能减小表层孔隙率.研究工作为复层含油轴承摩擦学性能分析与结构设计提供一定的理论基础.     

Thin-film multi-layer capacitors using Bi2Mg2/3Nb4/3O7 (BMNO) pyrochlore thin films via radio-frequency sputtering

Thin-film multi-layer ceramic capacitors (MLCCs) were prepared using high-dielectric constant Bi₂Mg_2/3Nb_4/3O₇ thin-films deposited at room temperature via radio-frequency magnetron sputtering. The multi-layer capacitors, in sizes 0402, 0603 and 1005, were well equipped with both inner and outer Cu electrodes. The capacitances of the bi-layer capacitors were twice that of the single-layer version in sizes 0402, 0603, and 1005. The 200 nm-thick Bi₂Mg_2/3Nb_4/3O₇ thin-films would be suitable for thin-film multi-layer capacitor applications.     

以学为中心理念下多层圆筒壁热传导教学设计及实施*

以多层圆筒壁热传导知识点为例,探索了以 “学”为中心教学模式的具体应用,结合智慧教学工具及手段,采用BOPPPS结构模式对教学重难点部分进行设计。实践结果表明,这种教学模式有利于激发学生的学习兴趣,提升学生的学习效果。     

Two-colour HgCdTe infrared detectors operating above 200 K

The performance of dual waveband HgCdTe photodiodes fabricated using metaloorganic chemical vapour deposition operated at high temperatures is presented. The effect of additional separating layer on the quantum efficiency and cross-talk of the photodiodes is analyzed. The photodiodes with cutoff wavelengths up to 6 μm, good R₀A product, and high quantum efficiency at 200 K have been demonstrated. The temperature dependence of the differential resistance is discussed. It is shown that the multilayer heterojunction P-n-N-n-P structure operating in a simultaneous mode has better performance than a structure operating in a sequential mode.     

中国城市竞争力评价量化模型研究

本文建立一种将主、客观指标赋权方法优点相结合的城市竞争力综合评价分层构权主成分分析模型,在构建中国城市竞争力综合评价指标体系的基础上,基于该模型方法给出31个中国主要城市的城市竞争力的评价实例。并以并以判别分析方法对相关评价结果进行校验,实证分析的结果表明:这是一种适合于城市竞争力定量评价、稳定性较好且切实有效的方法模型。     

含超导材料Thue-Morse序列一维光子晶体传输特性研究

超导光子晶体是一类重要的带隙可调谐的光子晶体.利用传输矩阵法研究了含超导材料的Thue -Morse序列准周期结构—维光子晶体在可见光波段的传输特性.数值结果表明在正入射时,光子带隙宽度和位置基本不随序列项数的增加而改变;准周期超导光子晶体的传输特性可以通过改变传统电介质材料的结构参数和环境温度等来进行调节.     

多层前馈模糊神经网络在儿童综合素质测评中的应用

运用对偶标度统计方法计算儿童发展调查问题中原始数据的变量权和样本得分,从而确定评价因素集.采用多层前馈模糊神经网络——FM LP实现对儿童个体综合素质的定量评价.     

Chargements axisymétriques d'un bicouche transversalement isotropeAxisymmetric loading on a transversely isotropic two-layered medium

An exact three-dimensional analysis is developped for an axisymmetric loading acting on the surface of a semi-infinite medium composed by two transversely isotropic materials. The loading is assumed to be parallel to the elastic symmetry axis of the upper layer. The solutions of a concentrated force and a uniform loading distributed on a circle are obtained by exact integral expressions. The numerical results are performed to show the anisotropic effect with isovalue curves of stress. To cite this article: C. Ruimy, M. Dahan, C. R. Mecanique 330 (2002) 469–473.