分析铁路改良粉细砂填料应用性能试验

在设计铁路路基的填料时,最常出现的是在进行铁路建设的地方就地取材。在以粉细砂为主的地区通常会选择用粉细砂作为铁路的填料,在所有的填料中,粉细砂填料属于C组类型填料,但是因为两个方面的原因需要对其进行一定的改良,一方面是因为粉细砂的粒径比较单一、级配不好,K30不能够满足规范标准的要求;另一方面则是因为大型机械不能够进行施工。本文通过掺入不同体积A、B组砾砂填料到粉细砂填料中进行试验,结果显示这种操作可以在不同程度上提高K30的值,从而在达到相关设计要求的同时解决施工方面的难题。     

IATA 58版变化和2017年锂电池运输规则要求

具体地描述了IATA 58版变化的主要概况,如启用两个有关锂电池的标签、不再需要托运人的声明和额外的说明文件、启用PI910的包装导则和张贴电池操作标记;分析了2017年锂电池运输规则要求的主要内容.     

中国东南部深源铀成矿与找矿:南岭铀成矿带讨论

对前人深源热液金属元素(包括铀)和铀成矿文献的综述可以得出:地幔流体-重大地质事件-成矿构造是深源铀成矿靶区勘查模式。探讨了南岭铀成矿带的成矿潜景和深层勘查方法,提示构造地球化学、金属活动态提取技术作为该区深源找铀矿方法所起的重要作用。     

Droplet Evaporation on a Hydrophilic Mesh Considering Their Sunken Shapes in Holes

The evolution of droplet shapes on a hydrophilic copper mesh was studied by using high-speed microscopic imaging technology. When a water droplet wets a hydrophilic mesh, the liquid-vapor interface initially adopts a convex shape, named as the “first darkness”. Then, as the water evaporates, the liquid-vapor interface flattens, and then it gradually adopts a concave shape; meanwhile, a “second darkness” forms. Taking the shapes of droplets sunken in holes into consideration, the quantitative liquid-vapor interface area was acquired. The evaporation coefficient becomes lower and more reasonable when considering the area increase due to the pentahedron sunken liquid in the holes. A speculation was employed to understand the observed evaporation behavior and the overprediction of the evaporation coefficient.     

35克素牛排单片重量控制方案探究

目的探究制定公司畅销产品大豆蛋白类食品35克素牛排的重量控制方案。方法研发人员通过查阅相关资料、采集生产与管理人员的意见、跟踪生产全程等手段获取实验方向,并通过小实验改变工艺条件和生产试验进一步验证工艺条件,探寻出了35克素牛排在生产过程中的重量变化规律、重量不稳定的主要原因及改进措施。结果 35克素牛排的单片重量与产品卤制工序呈影响极显著,与原材料重量、油炸工序差异显著。结论原材料控制在11克以上,油炸时间2分钟,最佳卤制时间10分钟,产品的单片重量合格率提高到90%以上。     

Strain‐rate‐dependent mechanical properties of polypropylene separator for lithium‐ion batteries

The mechanical integrity of battery separators is critical for battery safety and durability. A comprehensive study of strain‐rate‐dependent tensile and puncture properties of a polypropylene lithium‐ion battery separator is presented here with a new model. Due to anisotropy of the polymeric membrane, tensile testing was conducted for different directions. Results showed that tensile strength and elastic modulus were increased 1000% and 500%, respectively, for different directions. It was also demonstrated that tensile strength changed 10 to 25% with strain rate (1.67 × 10^?4 to 1.67 × 10^?1 s^?1) for different directions. An equation was obtained for the first time for flow stress versus strain rate at varied tensile directions with respect to machine direction. Moreover, puncture testing was performed and it was shown that puncture strength was increased 140% with increasing strain rate from 0.25 to 250 mm min^?1. Two failure modes were also observed in puncture samples. Finally, Eyring's model was used to calculate activation enthalpy of the porous polypropylene separator. © 2020 Society of Chemical Industry     

某型发动机自反馈调节阀动态仿真分析

基于FLUENT软件提供的计算方法和物理模型,利用动网格技术及用户自定义函数（User-define Function,UDF）,对发动机预燃室调节阀的自反馈调节过程进行动态数值模拟,并分析阻尼参数对调节效果的影响。结果表明：自反馈机构可实现对不同压力扰动的及时响应,具有稳定流量的效果,改变阻尼参数可对调节响应速度和流量稳定性进行优化,其中摩擦力对调节影响最显著。     

Thermal buffering effect of a packaging design with microencapsulated phase change material

Temperature fluctuations during storage and transportation are the most important factors affecting quality and shelf life of food products. Phase change materials (PCM) with their isothermal characteristics are used to control temperature in various thermal operations. In this study, octanoic acid as PCM candidate was used in a packaging material design for thermal control of a food product. The PCM candidate was microencapsulated in different shell materials in our laboratory. Among the synthesized microcapsules, microencapsulated PCM (mPCM) (ΔHm = 42.9 J/g) with styrene polymer as the shell material was selected based on its properties of being cost effective and compatibility with human health. Thermal buffering effect of PCM in bulk and microencapsulated forms was tested in a packaging design with special PCM pockets. Results showed that packages with mPCM and bulk PCM provided 8.8 and 6 hours of thermal buffering effect for 160 g of chocolate compared with the package without PCM (reference package).