Two typical phenomena from the numerical simulation of fire and smoke transport in a gymnasium fire

Building a large centralized atrium in a building has become favourable both to designers and owners. The space of an atrium in a hall, theatre or gymnasium, can occupy an area as large as thousands of square meters and a height as high as 10―30 meters[1…     

Studying the stability of the middle atmosphere (30―60 km) over Wuhan by Rayleigh lidar

The stability of the middle atmosphere ranging from 30 km to 60 km over Wuhan is elementarily studied, according to the observational data obtained in about one year through the WlPM Rayleigh lidar. The stability parameter （buoyancy frequency squared）, which was obtained through the temperature field, shows that the middle atmosphere over Wuhan is stable all the year round, but the stability appears variable because the stability of summer and winter is lower, and that of spring and autumn is higher.     

Some evidence of drying trend over northern China from 1951 to 2004

The surface wetness index, Palmer drought sererity index and the retrieval of soil moisture over China were calculated using monthly precipitation and monthly mean surface air temperature. Based on the contrast analysis of the variation of the above three indices and precipitation, the dry/wet spatio-temporal pattern of northern China in the last 54 years was revealed, and the evidence of drying trend over northern China was analyzed, especially. The results show the following four facts: (1) The drying trend is the main characteristic of the eastern part of Northwest China and the central part of North China since the 1980s and it was enhanced in the last 15 years mainly due to the precipitation decrease and the temperature increase; (2) During the last 54 years, there was only one dry/wet shift at the interdecadal scale occurring in the eastern part of Northwest China and the central part of North China in the late 1970s, which was related to 1977/1978 global abrupt change, whereas there were three shifts in Northeast China, one was in the mid 1990s and the other two were in 1965 and 1983, respectively; (3) Unlike the variation trend of other subregions of northern China, the western part of Northwest China is currently located in a relatively wetting period, which is weak-ened due to the temperature increase; (4) The extreme drought frequency is obviously increasing in the eastern part of Northwest China, the central part of North China and Northeast China since the 1980s, which is closely related to the precipitation decrease and temperature increase in these subregions.     

北京湿地生物资源保护与可持续利用对策初探

本文主要以2001年7月至2004年6月对北京湿地进行的大规模系统调查结果为基础，分析了北京湿地环境和生物资源的现状及其所面临的严重威胁，初步提出关于北京湿地生物资源保护与可持续利用的6点对策．     

可持续旅游开发与地域发展

旅游开发作为开发行为之一,依据其开发规模对旅游地产生了各种各样的影响.基于可持续发展的最新研究成果,对可持续旅游开发与地域发展的相互协调的关系进行了简单分析.为了实现可持续旅游开发,在社会和文化方面,必须要与地域产业、地域自然环境和地域共同体的三个侧面进行相互联系,使旅游开发不单成为获得经济效益的手段,也要成为地域建设的推动力,从而确立可持续旅游开发在建设富裕的、易于地方居民居住的旅游地域的综合核心的地位.     

液幕状气液两相流传热特性的实验研究

针对强化脱硫塔内气液两相流的传热与传质，建立了一种新的气液两相流型——液幕状气液两相流．根据该流型的特点，进行了气液两相传热实验，分析了气液两相流中的温度场分布，并研究了传热系数与液气比之间的关系．结果表明：无论顺流或逆流，在空气流速一定时，传热系数都随着液气比的增大而减小，并且液幕顶部是传热效果最佳的位置，可以组织多层液幕来降低工业成本．得到的传热系数与液气比之间的关联式为工程设计和更深一步的研究工作提供了技术标准．     

运用EWB测试线性系统特征参数

运用广泛使用的EWB(Electronics Workbench)电子实验台,对一、二阶线性系统特征参数进行测试实验。测试实验结果准确、可靠,并探讨出一种理论教学与实验教学有机融合的可行方法。     

集成化CAD—ZWG鼓形齿联轴器三维电子图库的开发

该文的研究课题是对机械行业标准件建库的一次大胆尝试 ,通过选择有代表性、适用性强的鼓形齿联轴器进行三维电子图库的开发性创建 ,为今后其他标准件三维电子图库的创建摸索出了一条比较成功的道路。     

电脑刺绣机新型挑线机构运动分析

以电脑刺绣机新型挑线机构为研究对象，推导了机构多位移矩阵迭代求解、机构速度和加速度的理论方程，详细分析了新型挑线机构的位移、速度、加速度特性曲线．结论显示加速度变化大是导致电脑刺绣机断线的原因之一．其推导方法与优化理论相结合可用于电脑刺绣机挑线机构参数设计，以改善加速度特性曲线，降低断线率．     

金属锰氮化的动力学研究

应用真空电阻炉高温渗氮、X射线衍射、惰气熔融法氧氮分析等实验测试方法,研究了金属锰在1173K含氮气氛中的氮化及动力学规律。渗氮时间愈长,试样的氮化量愈多。除有微量的MnO生成外,随渗氮时间的延长,金属锰可全部氮化为Mn4N和ζ-(Mn2N)。建立了金属锰氮化的动力学模型,与实验结果基本符合,能较好地反映氮化规律。