优势理论与几何不等式的证明

本文用优势理论的方法解决几个几何不等式的证明问题,这种方法的特点是构思容易,结论丰富。     

基于B/S模式的计算机机房管理系统设计

计算机机房管理是学校教学管理中非常重要的一个环节,但是很多单位的管理明显滞后于形势的发展,管理方式还停留在传统的模式上。文中笔者利用B/S的Web服务形式以信息化手段替代当前普遍采用的传统管理模式,寻求管理工作的创新。     

中学英语单词与大学英语单词互相衔接的调查与研究

文章通过对中学生英语词汇学习的调查,了解中学生学习词汇的情况,并针对大学生英语词汇学习的现状,提出了中学英语单词与大学英语单词互相衔接的重要性以及做好衔接工作的一些建议。     

校园文化的美育功能

校园的自然环境、人文环境、学校规章制度、文化活动及校风等校园文化内容具有独特的美育功能。加强高 校校园文化建设,充分发挥美育在思想政治工作中的渗透作用,对于提高大学生的人文素质具有重要意义。     

RL电路零输入响应的研究

本文通过实验 ,比较全面和系统的研究了RL电路零输入时的自感现象。不仅研究了时间常数、电流比对自感现象的影响 ,而且还特别研究了灯泡的灯丝温度在闪光亮度上的变化 ,从而得出一些有价值的实验结论     

新技术下的中专教学教材探索

新技术（计算机、计算器、网络）使学生更接近数学概念和拥有数学经验，使数学探索、数学实验以及提高概念的学习效果成为可能。     

Conversion of CO<Subscript>2</Subscript> to useful substances with composite iron,nickel, and copper catalysts

Composite materials of Fe/Al₂O₃, which consist of small particles of iron supported by thermally stable alumina even at 500–700 °C, have been widely used in the water-gas shift reaction for natural gas reforming. Therefore, Fe/Al₂O₃ is one of the promising candidates for re-transformation of exhausted CO₂ into fuels such as alcohols and hydrocarbons. The development of a CO₂ reforming system using the composite materials of Fe/Al₂O₃ through CO₂ reduction to CO, dissociation of water into hydrogen, and methanol synthesis has been investigated. It was found that dry and steam (i.e. wet) reforming of CO₂ produced almost the same amount of CO. At a temperature above 500 °C, maximal and saturated yields of CO and H₂ from CO₂ and water were obtained. However, this CO₂ reforming system requires higher-pressure conditions from several tens to hundreds standard atmospheric pressure in order to achieve high yield and selectivity for methanol production. In this study we developed the modified CO₂ reforming system by the utilization of Ni and/or Cu instead of Fe in order to obtain other types of useful products such as CO, CH₄, and carbon, more efficiently and selectively under atmospheric pressure. When Ni or Cu was used, conversion of CO₂ was reduced to 76%, while 9% of methane was detected in the case of Ni. On the other hand, though the CO₂ conversion reduced half of the Fe, the selectivity of CO from CO₂ increased to 95% in the case of Cu.     

Numerical investigation of cavitating flow behind the cone of a poppet valve in water hydraulic system

Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using advanced RNGk-epsilon turbulence model. The flow was turbulent, incompressible and unsteady, for Reynolds numbers greater than 43000. The working fluid was water, and the structure of the valve was simplified as a two dimensional axisymmetric geometrical model. Flow field visualization was numerically achieved. The effects of inlet velocity, outlet pressure, opening size as well as poppet angle on cavitation intensity in the poppet valve were numerically investigated. Experimental flow visualization was conducted to capture cavitation images near the orifice in the poppet valve with 30° poppet angle using high speed video camera. The binary cavitating flow field distribution obtained from digital processing of the original cavitation image showed a good agreement with the numerical result. Project supported by the National Natural Science Foundation of China (No. 59835160) and Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry of China (No. 50175097)