Stearic Acid/Copper Foam as Composite Phase Change Materials for Thermal Energy Storage

The application of stearic acid in the latent thermal energy storage(LTES) systems is hindered due to its lower heat transfer rate. Stearic acid(SA) was blended with copper foam(CF) of pore numbers per inch(PPI) of 5, 20, and 40 to prepare composite phase change materials via a molten impregnation method. The thermal physical properties including latent heat, phase change temperature, and thermal energy storage density of composites were characterized. The thermogravimetric analysis indicated th...     

Microwave-absorbing properties of de-aggregated flake-shaped carbonyl-iron particle composites at 2-18 GHz

We have investigated the microwave-absorbing properties for different shapes and aggregated states of carbonyl-iron particles dispersed in epoxy resin matrix at various volume concentrations. Here, we discuss the requirements of lower reflection coefficient for the microwave permittivity /spl epsiv//sub r/=/spl epsiv/'-j/spl epsiv/' and permeability /spl mu//sub r/=/spl mu/'-j/spl mu/'. Compared to the aggregated sphere-shaped particles (SS), the de-aggregated flake-shaped carbonyl iron particles (FS) have higher permeability, lower permittivity, better filling characteristics in epoxy resin, and better absorbing properties in the frequency range of 2-18 GHz. For the FS composite with volume fraction of 0.60 at single-layer thickness of 1 mm, the calculated reflection loss at 2 GHz reaches -4.04 dB and the minimum reflection loss is -12.2 dB at 4.4 GHz, which indicates that the FS composite can be applied as a thinner microwave absorber in the S-band than if SS particles are used. The results also show that different volume concentrations can have high absorption at different wave bands, a fact on which the design of absorbing material can be based.     

Progress and Applications of Plant Growth-Promoting Bacteria in Salt Tolerance of Crops

Saline soils are a major challenge in agriculture, and salinization is increasing worldwide due to climate change and destructive agricultural practices. Excessive amounts of salt in soils cause imbalances in ion distribution, physiological dehydration, and oxidative stress in plants. Breeding and genetic engineering methods to improve plant salt tolerance and the better use of saline soils are being explored; however, these approaches can take decades to accomplish. A shorter-term approach to improve plant salt tolerance is to be inoculated with bacteria with high salt tolerance or adjusting the balance of bacteria in the rhizosphere, including endosymbiotic bacteria (living in roots or forming a symbiont) and exosymbiotic bacteria (living on roots). Rhizosphere bacteria promote plant growth and alleviate salt stress by providing minerals (such as nitrogen, phosphate, and potassium) and hormones (including auxin, cytokinin, and abscisic acid) or by reducing ethylene production. Plant growth-promoting rhizosphere bacteria are a promising tool to restore agricultural lands and improve plant growth in saline soils. In this review, we summarize the mechanisms of plant growth-promoting bacteria under salt stress and their applications for improving plant salt tolerance to provide a theoretical basis for further use in agricultural systems.     

嫩江下游洪水演进及对洪泛区植被影响分析

为揭示嫩江下游洪水演进规律及对洪泛区植被的影响,利用MIKE FLOOD建立了嫩江江桥—大赉河段的一、二维水动力耦合模型,选取1998年与2013年汛期实测资料对河段糙率进行了率定与验证,并模拟了典型河段4种不同重现期洪水的演进过程。在此基础上基于2000—2019年MODIS卫星的MOD13Q1数据集,获取了不同洪水频率淹没范围内的植被指数(NDVI、EVI),评估了嫩江下游不同重现期洪水扰动对植被的影响。结果表明:模型在率定期与验证期的模拟效果符合甲级预报精度,模型模拟精度较高;不同重现期内的植被指数具有较强的季节变化规律,且洪水对植被具有明显的破坏作用,但这种破坏作用在嫩江流域周期性相对较短,表明该地区植被的可恢复性较强;同时受洪水频繁淹没程度影响,不同重现期的植被指数符合中度干扰假说。     

综掘工作面硫化氢运移规律及其防治技术

为掌握综掘工作面硫化氢的运移分布规律,基于湍流k—ε方程、动力弥散方程,构建硫化氢运移扩散的数学模型,对其运移扩散过程进行了模拟,并提出了泡沫吸收技术与水幕净化技术相结合的综合治理措施。结果表明：硫化氢自工作面涌出后受流场及重力的影响,其运移过程大致可分为重力扩散、被动扩散及均匀扩散3个阶段;在工作面类似“U”形通风系统下硫化氢最容易积聚在回风侧下隅角处。综合治理措施应用后,使掘进机割煤涌出的硫化氢体积分数由47.7×10^-6降低到6.0×10^-6,对硫化氢的有效去除率达到83.8%。     

PC/SBS共混物力学性能与形态的研究

本文系统地研究了PC与SBS共混体系的力学性能 ;通过SEM观察了共混物的形态结构 ;并对SBS增韧PC的机理进行了探讨 ;结合DSC分析结果表明 ,ABS g MAH对PC/SBS共混体系有很好的增容作用     

基于同步约束解除的零件爆炸图自动生成方法

面向结构教学及维修人员培训,提出了一种基于零件几何约束关系同步解除的爆炸图自动生成方法。在定义零件拆卸轴向的基础上,建立了零件邻接拆卸约束关系矩阵及约束类型矩阵,按照可同步解除几何约束的顺序对零件进行分层,并利用判断规则识别子装配体。结合应用OBB和FDH两种包围盒,提出了一种“由外向内”的等速率分层牵引零件爆炸分离方法,实现了装配体组成零件爆炸图的自动生成。     

医学断层图像三维重建的辅助轮廓线法

在原有的轮廓线基础上生成与之相似的辅助轮廓线．然后把各轮廓线三角化形成一层层的三角面片,最后按一定的规则把各层三角面片从外到内直接连接形成四面体,从而完成三维重构．文中算法尤其适合基于断层轮廓线的医学图象三维重构,与已有的三维重构法（如MC．MT,Delaunay四面体化）相比,具有算法简单、思路自然、易于实现的特点．     

钻井船仪表控制系统研制及硬件在环仿真测试

为有效提高钻井船生产过程火气安全切断的可靠性及船员的安全性,针对钻井船仪控系统工艺过程控制和安全切断的控制策略复杂度高,难以通过普通仪表测试,研制了具有网络冗余的分布式控制系统和采用具有安全等级的安全控制器搭建的钻井船安全仪表系统,并搭建了半物理仿真验证平台验证其控制逻辑的准确性。验证结果表明:该钻井船仪表控制系统样机的过程控制和安全系统的控制策略、关断策略安全有效,无线通讯和管理软件及报表分析、趋势预测等功能与实船需求相匹配;借助该仿真平台不仅可以优化控制效果还提高了测试效率。