Thermal degradation of corn starch based biodegradable plastic plates and determination of kinetic parameters by isoconversional methods using thermogravimetric analyzer

Oil shortage and awareness of environment pollution leads to the extensive use of biodegradable starch-based materials against synthetic plastics. The accumulated wastes of these plastics takes more time for natural recycling and the process is complex. Therefore the best option of recycling would be to convert these polymers into a source of energy by pyrolysis. So to understand the pyrolytic behaviour, kinetics of such waste plastics is studied by using thermogravimetric analysis at different heating rates of 10 °C, 20 °C, 40 °C, 60 °C, 80 °C and 100 °C in nitrogen atmosphere followed by characterization of the pyrolysis products. The kinetic parameters are obtained for two major stages of decomposition in two different temperature ranges 250–620 °C and 620–855 °C by iso-conversional methods such as Friedman, Coats-Redfern, FWO and Kissinger methods. The regression coefficient data (>0.9) of kinetic plots obtained for different methods best fits to the kinetic equation. Empirical formula of the compound is determined by ultimate analysis is CH_2.214S_0.0018O_0.6910. Proximate analysis gives the idea of volatile component which is74.33%. The range of average value of activation energy is 120.7013 kJ/mol to 140.7707 kJ/mol for the biodegradable plastic plate with different conversion (0.1–0.6) and (0.1–0.3) respectively at two different temperatures. The pyrolysis products obtained using a semi-batch reactor are characterized to know their composition and other properties.     

大直径平底负压容器优化设计

通过对大直径平底负压容器平底板的设计计算,平底板计算厚度很厚。通过分析,提出了对平底板采取加强措施,从而减薄平底板计算厚度的方法。该容器在实际生产过程中性能可靠、稳定,对类似设备设计具有借鉴意义。     

积极降压对脑小血管病防治策略的影响

2017年,美国心脏病学会和美国心脏协会提出将高血压诊断标准降为130/80 mm Hg (1 mm Hg=0. 133 kPa),这与其他指南有所不同。降压治疗的核心目标在于靶器官的保护,近年来降压治疗与脑小血管病预防的相关问题日益受到临床重视。目前研究结果表明,降压治疗对腔隙性卒中患者的二级预防以及白质病变进展的预防可能有一定积极意义,但确切的降压目标值并未确定。血压与临床结局可能呈现J型关系,血压过低或过高可能均有害,而取得最大获益的降压目标有待进一步探索。     

简体接管边缘应力区局部减薄处应力特征

参考《压力容器定期检验规则》第40条,采用有限元方法计算了筒体接管边缘应力区局部减薄处的应力分布,得到了局部减薄处凹坑的尺寸与位置对应力的影响趋势,讨论了应力集中系数随尺寸变化的规律,为筒体接管边缘应力区局部减薄处的强度评定提供了一定的计算依据。     

氟塑料—石墨板式换热器在高温强腐蚀换热工况中的应用

通过氟塑料－石墨板式换热器在化纤生产中高温强腐蚀换热工况中的实际应用，并与常规换热器的使用情况的对比分析，阐述了这种新型换热设备的特点。     

利用废旧塑料生产阻燃建筑装饰材料探讨

本文介绍了一种综合利用废旧热塑性塑料和锯末粉通过加入阻燃剂改性 ,生产防火阻燃型建筑装饰材料的方法。所生产的产品 ,其阻燃性能均达到国家标准 (GB5464 - 85)中规定的不燃性材料的要求。     

中小型渔船制冷技术的研究进展

远洋渔船带有制冷装置，而100吨以下的中小型渔船因其柴油机的限制，无法安装压缩机式制冷机。出海作业时，均需携带冰块做渔产保鲜。本文介绍压缩式渔船制冷的现状，回收渔船尾气余热的吸收式制冷系统，吸附制冷的冷冻水系统，吸附式制冰系统等实验装置。其中吸附式制冷系统具有良好的开发价值。     

塑料挤出型材车间公用工程设计

鉴于当今人们对塑料门窗需求量的增大，通过对5个塑料挤出型材车间的设计，将其公用工程设计整理成文，总结出塑料挤出型材车间的采暖通风设计，压缩空气系统设计，制冷系统设计的较详尽的方案，以供有关设计技术人员参考。     

Effect of refraction on optical microscopic measurement of internal blood-vessel diameter and its correction

In optical microscopic measurement of internal blood-vessel diameters, the effect of refraction must be taken into account to ensure accuracy of the result. This effect is discussed and an analytical correction formula derived. Phantom blood vessels with known internal and external diameters were used to test the validity of the correction formula. The errors obtained prior to correction were reduced significantly after correction.     

Theory to boil-off gas cooled shields for cryogenic storage vessels

An intermediate refrigeration with boil-off gas cooled shields using the boil-off gas stream is an alternative method to the conventional intermediate refrigeration with a cryogenic liquid.By using an analytical calculation method relations are derived, which enable complete predictions about the effectiveness of an intermediate refrigeration with boil-off gas cooled shields as a function of the number of shields for the different stored cryogenic liquids. For this theoretical derivation however, the restrictive assumption must be made that the thermal conductivity of the used insulation material has a constant value between the considered temperature boundaries.For purposes of a more exact calculation a numerical method is therefore suggested, which takes into consideration that the thermal conductivity is temperature-dependent. For a liquid hydrogen storage vessel with a perlite-vacuum insulation e.g., the effectiveness of one shield and its equilibrium temperature are given as a function of the position of the shield in the insulation space.