离心式三元叶轮叶片可展面造型规律的研究

针对钣料柱面叶片无法满足气动设计所规定的扭曲规律的要求和一般三元叶片加工复杂性的问题,本文提出了一种新的叶片造型方法:首先从S_2流面反命题的一组方程出发,进行三元叶片设计。然后,采用满足一条流线加载,其余加载流线用可展面进行最小二乘逼近的方法,将三元叶片面变成可展叶片面。为了验证新型面的气动性能,对其进行了性能实验,实验表明,气动性能是优良的。该设计方法具有广泛的应用前景。     

小雁塔日晷初探

本文为小雁塔日晷定了名,并从构造原理、使用方法、年代推断三方面进行探讨,认为它是赤道式日晷,是隋唐时代的物品。     

无孔型轧制时轧件展宽的研究

本文对无孔型轧制时轧件展宽进行了实验研究和理论分析,在定量分析歪斜轧件轧制时轧件单侧展宽的基础上,采用刚-塑性材料变分原理对歪斜轧件的轧制变形过程进行了解析,通过曲线拟合将最接近真实速度场的数值解表示成了具体的函数表达式,推导了无孔型轧制时轧件宽展系数的理论计算公式。理论计算的结果与实验结果符合很好。     

边界积分方程数值解法及其应用(Ⅱ)

本文推广了中的结果,对于三维问题,利用多元插值和边界型求积公式给出边界积分方程一种新的数值解法。     

方形柱体外侧自然对流换热的干涉仪研究

本文用Mach-Zehnder干涉仪对置于空气中水平方形柱体的大空间自然对流换热进行了系统的实验研究.得到了柱体底面与水平线成各种倾角下的温度场;整理了不同倾角下平均Nu数随Ra数变化的关系式;分析了底面倾角对整体换热影响的机理,得出了倾角等于45°时换热最强的结论;分析了不同倾角下局部Nu数沿壁面变化的原因,尖角对换热的影响.并对自然对流流动分离进行了探讨,认为方形柱体在各种倾角下,Ra数超过一定值时,均会产生流动分离,分离的可能性随Ra数的增高而加大.     

创建学习型城市的思考

建设学习型城市的最终目的，就是为了不断提高市民的综合素质，促进人的全面发展，进而推动经济、科技、文化的全面发展。建设学习型组织，不能简单地等同于传统的一般性的学习方式的改进，是一场深刻的管理革命。在推进教育现代化、社会化，其主旨不能等同于打造“大学城”，应把构建终身教育体系作为创建学习型城市的重大目标。     

一类线性切换系统基于观测器的输出反馈镇定

对一类线性切换系统 ,首先设计了其状态观测器的形式 ,给出线性切换系统渐近镇定的一组LMI形式的充分条件 .基于所设计的观测器 ,用各子观测器的值构造各子控制器和切换策略 ,达到使整个闭环系统渐近稳定的目的 .对切换时间周期受限制情况 ,给出其相应的指数镇定控制策略 .最后给出一个仿真实例以说明本文设计方法的正确性 .     

Isolation and Characterization of Phytoene Desaturase cDNA from Stigma of Crocus sativus

Phytoene desatumse (PDS) has recently been identified as an important enzyme in carotenoid biosynthesis pathway. A cDNA clone encoding phytoene desaturase gene is isolated from stigma of saffron (Crocus sativus L. ) using RT-PCR technique. Sequence analysis shows 85% similarity to Narcissus pseudonarcissus, 79% to Zea mays, 78% to Arabidopsis thaliana, 77% to Lycopersicon esculentum. A new full-length cDNA is obtained by 5 ‘-RACE and 3‘ -RACE techniques. The cDNA is 2149bp long with an open reading frame of 1697bp, which encodes a polypeptide of 565 amino acids. Southern analy-sis shows that the PDS gene is a single copy in saffron. Northern blot analysis shows higher expression level of PDS gene in stigma and anther than in leaves and stem.     

Experimental investigation of integrated air purifying technology for bioaerosol removal and inactivation in central air-conditioning system

In this research, high voltage static electricity and ultraviolet technologies were integrated to an air purifying device which can be used to trap and kill airborne bacteria and viruses in central air-conditioning systems. An experimental platform was built to mimic the central air system, in which the efficacy of the newly built device was examined. In addition to the standard physical and chemical tests, bacteriophages were used to simulate airborne viruses in the experimental system. The bacteriophage suspension was aerosolized into the air with ultrasonic wave atomization. The result showed that more than 86% removal efficiency of micro-particles (<10 micron in diameter) were removed after the device was in operation in a building and more than 95% of bacteriophages in the experimental system. It is concluded that the integrated air purifier is suitable for controlling air quality and preventing virus transmission through the central air system.