美国空间探测器热防护材料发展现状及趋势

综述了美国空间探测器热防护材料的发展及现状,介绍了几类具有代表性的防热材料:高密度酚醛玻璃钢、DC-325、Avcoat、SLA-561、PICA(Phenolic impregnated carbon ablator)和碳酚醛等,及其所应用的探测器、气动加热环境和防热结构成型工艺,着重阐述了美国在研的猎户座载人登月飞船防热材料的研制情况,并介绍了两类热点的烧蚀防热材料在以往研制过程中出现的异常情况以及选材的变化及进展,总结了猎户座的研制经验,同时指出了后续空间探测器防热结构及材料的发展方向。     

机械零件表面应力等值线表示方法研究

在AutoCAD环境下,对机械零件表面所受应力的等值线表示方法进行了研究.     

餐馆分级 形同虚设

找宾馆住宿,人们第一反应是先看它是几星级,可到餐厅吃饭,却很少有人考虑同样的问题。今年1月,国家食品药品监督管理局发布了《关于实施餐饮服务食品安全监督量化分级管理工作的指导意见》,将对餐饮服务单位的食品安全情况进行量化评级,安全级别统一用＂笑脸＂等符号表示。在此之前,全国各地还实施了给餐馆分级的制度,各地卫生局用A、B、C、D对餐饮单位进行卫生等级考核。     

酶制剂与酵母复合膨松剂在油条制作中的应用

该研究以油条为例探究食品酶制剂和酵母用作传统油炸面制品膨松剂的可行性。通过膨胀率、比容、感官评定等检测方法对常用面制品膨松剂的效果、食品酶制剂与酵母复配的效果进行了评估,并对复配效果最佳的组合进行发酵过程分析。结果发现常用面制品膨松剂中明矾膨松效果最好,油条最大膨胀率为8.73倍。以酵母为基础膨松剂进行改良,利用蛋白酶、淀粉酶、脂肪酶、木聚糖酶、葡萄糖氧化酶与酵母复配,结果发现淀粉酶效果最好,在添加量为0.50 g/kg的情况下膨胀率达到了7.65倍。对淀粉酶酵母组合膨松剂进行发酵过程分析,发现面团最佳发酵时间为2.5 h,面制品中碳水化合物大幅度降解为还原糖,含量达到5.25%。这种新型复合膨松剂成分由食品酶和食品微生物组成,无铝元素添加,在保证膨松效果的前提下实现了安全健康的目的。     

扎染在现代服饰中的时尚运用

扎染是传统而古老的印染技术,其自身魅力使扎染文化与技法流传至今。随着时代的发展,扎染工艺不断与当今科技文化融合创新,在人们对个性时尚的强烈追求下,扎染风潮于近年强势回归,为现代服饰带来了新的活力。现主要针对扎染与现代服饰时尚、风格、工艺和搭配等方面展开探究。     

以凸轮机构控制转向的无碳自行小车研究

根据无碳小车自动变距绕桩行走要求,采用凸轮机构控制转向,建立了小车转向机构的数学模型.利用MatIab软件计算并优化其相关参数,通过仿真分析了转向机构各参数变化对小车行驶轨迹的影响,得到了转向机构各参数与小车行驶轨迹之间的关系.基于优化后的参数值,制作了实车,通过实车调试验证了参数优化后转向机构设计的合理性和可靠性.     

Numerical investigation on the effect of gas parameters on ozone generation in pulsed dielectric barrier discharge

Pulsed dielectric barrier discharge is a promising technology for ozone generation and is drawing increasing interest. To overcome the drawback of experimental investigation, a kinetic model is applied to numerically investigate the effect of gas parameters including inlet gas temperature, gas pressure, and gas flow rate on ozone generation using pulsed dielectric barrier discharge. The results show that ozone concentration and ozone yield increase with decreasing inlet gas temperature, gas pressure, and gas flow rate. The highest ozone concentration and ozone yield in oxygen are about 1.8 and 2.5 times higher than those in air, respectively. A very interesting phenomenon is observed: the peak ozone yield occurs at a lower ozone concentration when the inlet gas temperature and gas pressure are higher because of the increasing average gas temperature in the discharge gap as well as the decreasing reduced electric field and electron density in the microdischarge channel. Furthermore, the sensitivity and rate of production analysis based on the specific input energy (SIE) for the four most important species O₃, O, O(1D), and O₂(b¹∑) are executed to quantitatively understand the effects of every reaction on them, and to determine the contribution of individual reactions to their net production or destruction rates. A reasonable increase in SIE is beneficial to ozone generation. However, excessively high SIE is not favorable for ozone production.     

重庆直辖以来地方性法规发展历程回顾——从追求数量到提高质量

地方立法是地方民主法制建设的一个重要方面,重庆作为全国最年轻和西部唯一的直辖市,鲜明的地方特点决定了其独特的立法模式,通过梳理重庆市自直辖以来所颁布的211部地方性法规,分析概括每一阶段的立法特点发现重庆市的地方立法总体发展呈现出从最初的数量型发展到质量型发展的一种趋势.     

高含硫气田井底落鱼井安全生产技术探讨(70)

在高含硫气井完井作业过程中,由于操作失误导致作业工具掉入井下形成井底落鱼.落鱼打捞作业难度大,滞留井底易产生腐蚀,形成残渣.为解决腐蚀残渣冲蚀、堵塞井筒及生产设备等问题,在落鱼腐蚀特征研究的基础上,应用临界冲蚀流量、临界携硫颗粒流量及临界携液流量模型,通过气井产能优化,建立安全生产工艺.     

Study of Microbiologicaily Induced Corrosion Action on Al-6Mg-Zr and Al-6Mg-Zr-Sc

The corrosion behaviors of Al-6Mg-Zr and Al-6Mg-Zr-Sc in the sulfate-reducing bacteria （SRB） solution in anaerobic environment were studied using electrochemical, microbiological, and surface analysis methods. It was found that the oxide film was more compact owing to the addition of Sc resulting in the open circuit potential shifting by about 100mV positively. On the other hand, it was seen that the pitting sensitivity of Al-6Mg-Zr-Sc alloy in SRB solution decreased and its microbiologically influenced corrosion resistance was improved. Pitting corrosion occurring on the surface of the two alloys under the comprehensive action of the metabolism of SRB was observed by SEM. It was obtained by EDS that the corrosion degree increased with time and corrosion was furthered by deposition of the product.