政务信息资源目录体系技术概述

政务信息资源目录体系是政务信息资源开发和利用的基础设施，主要介绍了包括政务信息资源目录体系的基本概念、主要作用．关键标准。支撑技术及应用模式。     

自然对流条件下两种垂直放置纵向翅片管传热特性的数值分析

采用数值计算的方法对垂直放置的封闭式纵向翅片管和开放式纵向翅片管自然对流条件下的传热特性进行研究，得到了在基管恒壁温条件下两种不同类型翅片管周围的温度场与速度场，及其散热量、金属热强度及自然对流换热系数。结果表明，封闭式纵向翅片管的散热量、金属热强度以及自然对流换热系数都要高于开放式翅片管。因此在结构参数一定时，封闭式纵向翅片管要优于开放式翅片管。     

Preparation and characterization of La1−xSrxNiyFe1−yO3−δ cathodes for low-temperature solid oxide fuel cells

Perovskite-type La_1−xSr_xNi_yFe_1−yO_3−δ (x = 0.3, 0.4, 0.5, 0.6, y = 0.2; x = 0.3, y = 0.2, 0.3, 0.4) oxides have been synthesized and employed as cathodes for low-temperature solid oxide fuel cells (SOFCs) with composite electrolyte. The segregation of La₂NiO_4±δ is observed to increase with the increasing Sr²⁺ incorporation content according to X-ray diffraction (XRD) results. The as-prepared powders appear porous foam-like agglomeration with particle size less than 1 μm. Maximum power densities yield as high as 725 mW cm⁻² and 671 mW cm⁻² at 600 °C for fuel cells with the LSNF4628 and LSNF7337 composite cathodes. The maximum power densities continuously increase with the increasing Sr²⁺ content in LSNF cathodes, which can be mainly ascribed to the possible charge compensating mechanism. The maximum power densities first increase with the Ni ion incorporation content up to y = 0.3 due to the increased oxygen vacancy, ionic conductivity and oxygen permeability. Further increase in Ni ion content results in a further lowering of fuel cell performance, which can be explained by the association of oxygen vacancies and divalent B-site cations in the cathode.     

Development of trimetallic Ni–Cu–Zn anode for low temperature solid oxide fuel cells with composite electrolyte

Trimetallic alloys of Ni_0.6Cu_0.4−xZn_x (x = 0, 0.1, 0.2, 0.3, 0.4) have been investigated as promising anode materials for low temperature solid oxide fuel cells (SOFCs) with composite electrolyte. The alloys have been obtained by reduction of Ni_0.6Cu_0.4−xZn_xO oxides, which are synthesized by using the glycine–nitrate process. Increasing the Zn content x decreases the particle sizes of the oxides at a given sintering temperature. Fuel cells have been constructed using lithiated NiO as cathode and as-prepared alloys as anodes based on the composite electrolyte. Peak power densities are observed to increase with the increasing Zn addition concentration into the anode. The maximum power density of 624 mW cm⁻² at 600 °C, 375 mW cm⁻² at 500 °C has been achieved for the fuel cell equipped with Ni_0.6Zn_0.4 anode. A.c. impedance results show that the resistances dramatically decrease with increasing temperatures under open circuit voltage state. Both cathodic and anodic interfacial polarization resistances increase with the amplitude of applied DC voltage. Possible reaction process for H₂ oxidation reaction at anode based on composite electrolyte has been proposed for the first time. The stability of the fuel cell with Ni_0.6Cu_0.2Zn_0.2 composite anode has been investigated. The results indicate that the trimetallic Ni_0.6Cu_0.4−xZn_x anodes are considerable for low temperature SOFCs.     

变频器频率测试仪

介绍了变频器颁率测试仪的测试原理及其电路框图．该仪器具有通信接口，可以和通用计算机构成双机或多机系统．它应用于自动生产线上，最多可测１６台变频器的输出频率、电动机转速和辊道线速度．