Double-perovskites YBaCo2−xFexO5+δ cathodes for intermediate-temperature solid oxide fuel cells

Double-perovskites YBaCo_2−xFe_xO_5+δ (YBCF, x = 0.0, 0.2, 0.4 and 0.6) are synthesized with a solid-state reaction and are assessed as potential cathode materials for utilization in intermediate-temperature solid oxide fuel cells (IT-SOFCs) on the La_0.9Sr_0.1Ga_0.8Mg_0.115Co_0.085O_2.85 (LSGMC) electrolyte. The YBCF materials exhibit chemical compatibility with the LSGMC electrolyte up to a temperature of 950 °C. The conductivity of the YBCF samples decreases with increasing Fe content, and the maximum conductivity of YBCF is 315 S cm⁻¹ at 325 °C for the x = 0.0 sample. A semiconductor-metal transition is observed at about 300-400 °C. The thermal expansion coefficient of the YBCF samples increases from 16.3 to 18.0 × 10⁻⁶ K⁻¹ in air at temperatures between 30 and 900 °C with increase in Fe content. The area-specific resistances of YBCF cathodes at x = 0.0, 0.2 and 0.4 on the LSGMC electrolyte are 0.11, 0.13 and 0.15 Ω cm² at a temperature of 700 °C, respectively. The maximum power densities of the single cells fabricated with the LSGMC electrolyte, Ce_0.8Sm_0.2O_1.9 (SDC) interlayer, NiO/SDC anode and YBCF cathodes at x = 0.0, 0.2 and 0.4 reach 873, 768 and 706 mW cm⁻², respectively. This study suggests that the double-perovskites YBCF (0 ≤ x ≤ 0.4) can be potential candidates for utilization as IT-SOFC cathodes.     

The application and research of high-frequency ultrasonic reflection technique used in the measurement of small diameter’s tube cavity size

Based on the problems that the photoelectric detection method and the X-ray testing method cannot provide the ideal accuracy when they are applicated to detect the cavity of small workpiece with diameter Φ6 mm and the general probes cannot stretch to the internal of the workpiece, we propose a high-frequency ultrasonic reflection technique which is used to measure the cavity size of diameter tube. The method uses ultrasound to measure the thickness. It can extract information about the wall size of workpiece through signal processing, feature extraction and other methods. By using this information, we can measure the size of cavity. Compared with the test results showed by a venire caliper and screw micrometer, we can get the conclusion that the immersion focusing probe with center frequency of 10 MHz can accurately detect the cavity of the workpiece. The experiment shows that the method gives consideration to the accuracy and computational efficiency of the workpiece’s cavity parameters. It can get data supplely and effectively. There are other advantages of this method such as stable performance, easy installation, and lower power consumption and penetration ability. It is suitable for the precision measurement of the workpiece.     

Model updating based on incomplete modal data

The objective of model updating is to improve the accuracy of a dynamic model based on the correlation between the measured data and the analytical (finite element) model. In this paper, we intend to update the mass and stiffness matrices of an analytical model when only modal frequencies or spatially incomplete modal data are available. While the proposed method is systematic in nature, it also preserves the initial configuration of the analytical model, and physical equality and/or inequality constraints ...     

A NONDESTRUCTIVE METHOD TO MEASURE RESIDUAL ADSORPTION CAPACITY OF CHARCOAL FILTERS

High surface area charcoal bed filters have been used for over a half a century to adsorb undesirable vapors from gas streams. One problem encountered when using these niter beds is that there is presently no simple, reliable, nondestructive method to measure their Residual Adsorption Capacity, RAC. This is particularly critical in situations where harmful vapors are being adsorbed.

An investigation has been underway to use pulses of weakly adsorbed gases such as ethane and/or methane to measure RAC. The hypothesis being that these weakly adsorbed gases will “count” unoccupied adsorption sites. In the present study, dimethyl methylphosphonate (DMMP) was used to “irreversibly” occupy available siles to various extents on different niters. The Reduced Retention Time. θ, (the ratio of the adjusted retention time to the space time) and the Resolution (R) between peaks of methane and ethane were found to correlate to RAC under dry and wet (humid) conditions.     

Impact analysis of static voltage assessment based on three‐phase probabilistic load flow with correlated wind power

Impact analysis based on the three‐phase probabilistic load flow (PLF ) algorithm is proposed in this paper to evaluate the effect on static voltage of an unbalanced power system. Correlations between adjacent wind power resources are considered. An improved cumulants method with correlated variables is proposed and applied to the unbalanced system. Cornish–Fisher expansion is used to obtain the cumulative distribution function of bus voltage and line flow. The impacts for wind turbines , which include rated capacity, power factor, and correlation on PLF, are studied, and the relations of the means and standard deviations between three‐phase unbalanced and balanced systems are analyzed. A 25‐bus and a 33‐bus system are studied as examples to show the effectiveness of proposed method, and results of cumulants method are compared with those of Monte Carlo simulations. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Isothermal tube flow of non-linear viscoelastic fluids. Part II: Transversal field

Constitutive criteria for the existence of secondary flows, similarities and analogies, developments in the history of transversal flows, recent research on secondary flows of dilute solutions in rotating pipes and channels and related drag reduction are reviewed in depth as well as research concerning fundamental aspects of transversal flows and industrial applications relevant to secondary flows.     

Composites with needle-like inclusions exhibiting negative thermal expansion: A preliminary investigation

In this work a simple cylindrical structure with a stiff needle-like inclusion embedded within a much softer matrix is presented and analysed with the aim of obtaining a system with tunable thermal expansion properties. It is shown that by the correct combination of the thermal and mechanical properties of the matrix and inclusion, it is possible to design a system which can be tailor-made to exhibit particular values of the coefficient of thermal expansion (CTE) in the radial direction and also negative thermal expansion (NTE). In particular an analytical model to quantify the radial strain with changes in temperature is derived and verified through finite element analysis. The model is used to find correct property combinations which lead to particular values of thermal expansion which could also be negative or zero.     

Urbanisation Induced Landscape Change of Urban Hills in Jinan City,Karst Geological Region of North China

Rapid economic development has induced urbanisation in China, especially in most of China's karst geological mountain regions. Jinan City belongs to the karst geological mountain region of north China and is well known for its fractured karst springs. The spatial pattern of its land use has been profoundly transformed by rapid urbanisation, and the urban hills are facing changes in the city. Although the urban area of Jinan City keeps enlarging and the dwelling conditions are increasingly improving, the destruction of Jinan's urban hills occurs owing to the mass construction of the market housing and excessive real estate investment in the karst mountainous region within the city, thereby resulting in the degradation of the urban mountainous environment and threatening the settlement safety of Jinan's residents.     

大型CFB锅炉流化床非金属膨胀简要介绍

文中较为全面地分析了大型CFB锅炉流化床非金属膨胀节的结构特点、安装位置、运行前的检查。     

钢桁架筒结构基于刚度的设计方法——一种可持续的方法

桁架筒结构是高层建筑的一种高效的结构体系,该结构体系形式,自60年代末问世以来已广泛应用于大多数高层建筑中。提出基于刚度的设计方法,用以初步确定高层建筑桁架筒结构的构件尺寸。该方法适用于40～80层高的建筑物,并给出对应于代表性的设计荷载,使用材料最为经济的设计参数。就结构构件的不同几何配置对于设计经济性的影响进行了讨论,并对几何配置优化提出了建议。基于刚度的设计方法,只需较少迭代过程,非常适合于桁架筒结构的初步设计。对使用最少量的资源以满足构建建筑环境要求的设计,将具有推动和促进作用。