典型传输线网络对电磁脉冲的响应规律研究

针对关于电磁脉冲对各种低压传输网络及其重要电子终端设备的传导耦合规律、效应评估和损伤机理的研究较少,更缺乏有效防护措施的现状,运用电磁拓扑理论中的BLT方程进行了传输线网络对电磁脉冲响应规律的研究。首先进行了理论分析,在对传输线网络进行瞬态响应求解时,改进了以往利用繁琐的Fourier变换和反变换的计算方法,采用频域上的BLT方程求出传递函数,并结合时域上的卷积进行求解,缩短了计算时间、提高了计算结果的准确性。为了验证此方法的有效性,利用同轴线建立典型传输线网络,以方波为注入源进行了实验,实验测试结果与计算仿真结果基本一致。     

Frictional contact problem between a functionally graded magnetoelectroelastic layer and a rigid conducting flat punch with frictional heat generation

In this study, we consider the frictional sliding contact problem between a functionally graded magnetoelectroelastic (MEE) layer resting on a perfectly insulated rigid half plane and a perfectly conducting rigid flat punch with frictional heat generation. The punch is subjected to magnetoelectromechanical loads. The graded layer is modeled as a nonhomogeneous medium with a transversely isotropic stress–strain law and an exponential variation of the magnetoelectrothermoelastic properties along the thickness direction. Neglecting inertia effects and assuming a constant friction coefficient, the solution is obtained within the framework of steady-state plane magnetoelectrothermoelasticity under plane strain conditions. The heat equation is first solved using Fourier transform to yield the temperature field in the layer which is then substituted in the MEE governing equations. These equations are solved analytically using the same transform leading to three coupled Cauchy-type singular integral equations in which the main unknowns are the normal contact stress, the electric displacement, and the magnetic induction. These equations are then solved numerically to obtain the distributions of the normal contact stress, electric displacement, and magnetic induction at the surface of the graded medium. The main objective of this paper is to study the effect of the nonhomogeneity parameter; the friction coefficient; and the elastic, electric, and magnetic coefficients on the surface contact pressure, electric displacement, and magnetic induction distributions for the case of flat punch profile.     

高性能导静电乳液胶粘剂的制备

研究借鉴无皂乳液聚合机理,加入导电纤维丝,制备了用于粘贴导静电聚氯乙烯地板胶粘剂。研究了影响胶接强度、初粘力和导静电性能的主要因素,及乳化剂和交联单体对乳液稳定性和胶接强度的影响,确定丙烯酸丁酯与丙烯腈较合适的质量比为2∶1;适量加入甲基丙烯酸和甲基丙烯酰胺可以减少乳化剂的用量,可提高乳液的性能。得到的导静电乳液胶粘剂胶接最高强度达到0.70MPa,最好的导静电性可达到7.8×103Ω,均超过国家标准。     

Exergoeconomic and exergoenvironmental evaluation of power plants including CO2 capture

CO₂ capture from power plants, combined with CO₂ storage, is a potential means for limiting the impact of fossil fuel use on the climate. In this paper, three oxy-fuel plants with incorporated CO₂ capture are evaluated from an economic and environmental perspective. The oxy-fuel plants, a plant with chemical looping combustion with near 100% CO₂ capture and two advanced zero emission plants with 100% and 85% CO₂ capture are evaluated and compared to a similarly structured reference plant without CO₂ capture. To complete the comparison, the reference plant is also considered with CO₂ capture incorporating chemical absorption with monoethanolamine. Two exergy-based methods, the exergoeconomic and the exergoenvironmental analyses, are used to determine the cost-related and the environmental impacts of the plants, respectively, and to reveal options for improving their overall effectiveness.For the considered oxy-fuel plants, the investment cost is estimated to be almost double that of the reference plant, mainly due to the equipment used for oxygen production and CO₂ compression. Furthermore, the exergoeconomic analysis reveals an increase in the cost of electricity with respect to the reference plant by more than 20%, with the advanced zero emission plant with 85% CO₂ capture being the most economical choice. On the other hand, a life cycle assessment reveals a decrease in the environmental impact of the plants with CO₂ capture, due to the CO₂ and NO_x emission control. This leads to a reduction in the overall environmental impact of the plants by more than 20% with respect to the reference plant. The most environmentally friendly concept is the plant with chemical looping combustion.     

Oxygen permeation through dense La0.1Sr0.9Co0.8Fe0.2O3−δ perovskite membranes: Catalytic effect of porous La0.1Sr0.9Co0.8Fe0.2O3−δ layers

The oxygen permeation performance of a number of La_0.1Sr_0.9Co_0.8Fe_0.2O_3−δ (LSCF1982)-based membranes, consisting of dense LSCF1982 layer with/without porous LSCF1982 layer, was analyzed on the basis of the thickness of the dense layer and catalytic effect of the porous layer. A 0.27 mm thick dense membrane gives oxygen permeation flux ($J_{O_2}$) of 2.33 sccm min⁻¹ cm⁻² at 900 °C, which is increased to 3.55 sccm min⁻¹ cm⁻² on applying a porous layer of LSCF1982 onto the dense membrane. The membrane gives a stable flux for 300 h. The flux was further improved by reducing the thickness of the dense LSCF1982 layer and at 950 °C a flux of 4.47 sccm min⁻¹ cm⁻² is obtained with 0.012 mm thick membrane.     

Large diameter carbon fibres from mesophase pitch

Large diameter carbon fibres of 15-60 μm were produced from naphthalene-derived mesophase pitch. In the as-spun state, preferred orientation increases with fibre diameter, confirming a previous study. However, the sheath-core structure that develops during carbonisation of large diameter fibres results in a decrease in preferred orientation. As a consequence, the strength, modulus and electrical resistivity also decrease. The coarse optical texture of the partially relaxed core allows a higher degree of graphitisation. With extended stabilisation, the core can be eliminated and the mechanical properties improve whilst the electrical resistivity increases.     

铝球化学镀银工艺的研究

利用聚多巴胺对铝球表面进行预处理,再通过化学镀方法在聚多巴胺改性的基体表面制备金属银层。采用X光电子能谱仪分析聚多巴胺改性基体表面的元素组成,并分别采用X射线衍射仪和扫描电子显微镜表征镀银铝球的晶相结构与表面形貌。结果表明:当硝酸银的质量浓度为10g/L时,在铝球表面可形成直径约为20nm的单质银,镀银铝球的导电性优良,电导率达10 000S/cm。     

一种新型电解质锂盐的合成技术进展

综述了锂离子电池电解质锂盐的最新研究成果,介绍了一种新型的电解质锂盐的合成方法,并对电化学氟化和普通的化学合成方法进行了比较,阐述了该锂盐合成方法的可能发展方向。     

注塑冷却管网的简化计算

给出了作者推导的冷却管道椭圆积分项计算公式，分析了它的复杂性，采用降维处理方法，将原来的二维管道单元简化为一维线单元，简化了计算，提高了计算速度，缩短了计算时间。     

Anisotropic alignment of nickel particles in a magnetic field for electronically conductive adhesives applications

Anisotropically conductive adhesives were developed by magnetic alignment of conductive nickel particles in a non-conductive epoxy matrix. Conductivity occurs in the direction of the magnetic field applied to the adhesive film. The effects of magnetic and conducting nickel filler type (i.e. powders, filaments, flakes, and fibers), resin viscosity, and the magnitude of aligning magnetic field on the electrical properties of the resulting anisotropic adhesive were investigated. The electrical resistance of the anisotropic adhesive was measured using the four-point probe method. The resistance of the filled adhesive decreased with increasing viscosity and the intensity of the magnetic field.