Observations Of The Morning Transition Of The Convective Boundary Layer

The morning transition between the stable nocturnal situation and the daytime convective boundary layer (CBL) is of interest both for basic understanding and for initializing prognostic models. While the morning growth phase of the CBL has been studied in detail, relatively little has been published on the transition itself. In this paper, conventional observations of surface temperature, humidity, and turbulent fluxes,and data from a meteorological tower, are combined with measurements of the onset of convection by boundary-layer wind profilers to explore the timing and behaviour of the transition period. The transition is defined here as the period between sunrise and the time at which the depth ofconvection reaches about 200 m AGL. Diagnostic relationships based on surface heat flux, the temperature difference between 2 m and 200 m, and bulk Richardson number are explored. The transition is foundto be enabled by surface heating relaxing the surface stability, while the warming of the layerbetween 2 m and 200 m is in large part due to shear-driven entrainment.     

春季气温异常与影响台州地区台风的关系

引　言台风影响台州地区时 ,往往对社会、经济的发展和人民的生命、财产带来严重的损失 ,当地领导对此十分重视。为此 ,每年临近台风季节 ,我们总是把台风的预报 ,特别是对台风的长期预报作为重中之重来抓。以往我们采用当年 1～ 3月份的降雪对应的韵律关系、回归方程和其它预报因子等工具来制作预报 ,但这些预报往往发生空报、漏报。现采用单站要素结合厄尔尼诺现象来预报有无影响台州地区的台风 ,取得了较好的预测效果。1　异常的春季气温与 8～ 9月份影响台州地区台风的关系1 1　厄尔尼诺 (不跨年度 )年春季气温与台风的关系每年 2月下…     

MONTBLEX tower observations: Instrumentation,data acquisition and data quality

Tower platforms, with instrumentation at six levels above the surface to a height of 30 m, were used to record various atmospheric parameters in the surface layer. Sensors for measuring both mean and fluctuating quantities were used, with the majority of them indigenously built. Soil temperature sensors up to a depth of 30 cm from the surface were among the variables connected to the mean data logger. A PC-based data acquisition system built at the Centre for Atmospheric Sciences, IISc, was used to acquire the data from fast response sensors. This paper reports the various components of a typical MONTBLEX tower observatory and describes the actual experiments carried out in the surface layer at four sites over the monsoon trough region as a part of the MONTBLEX programme. It also describes and discusses several checks made on randomly selected tower data sets acquired during the experiment. Checks made include visual inspection of time traces from various sensors, comparative plots of sensors measuring the same variable, wind and temperature profile plots, calculation of roughness lengths, statistical and stability parameters, diurnal variation of stability parameters, and plots of probability density and energy spectrum for the different sensors. Results from these checks are found to be very encouraging and reveal the potential for further detailed analysis to understand more about surface layer characteristics.     

防止烟囱、水塔爆破倾倒时后座现象的技术

引起烟囱水塔等细高型建筑物爆破损倒时的后座现象的两大因素，即爆破切口长度和切口形状。并在控爆实践中提出有效防止后座现象的确定方法和计算公式。     

框架塔自振频率的数值解法

框架和塔连接后可简化为一个弹性支承的系统,利用弹性连续体分析法求解振动方程,推导出了计算框架塔自振频率的理论公式。试验结果表明:本模型的计算值与试验值吻合良好,可以为工程实践中的应用提供理论依据。     

广西天气预报视频会商系统网管软件的操作及常见问题诊断

简要介绍广西天气预报视频会商系统中心控制平台的基本操作方法，并针对在业务运行中出现的常见故障，进行原因分析，并找出解决方法。     

Dynamic performance of cable-stayed bridge tower with multi-stage pendulum mass damper under wind excitations --Ⅰ： Theory

In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper （MSPMD） is investigated. Special attention is given to overcoming space limitations for installing the control device in the tower and the effect of varying natural frequency of the towers during construction. First, the finite element model of the bridge during its construction and the basic equation of motion of the MSPMD are introduced. The equation of motion of the bridge with the MSPMD under along-wind excitation is then established. Finally, a numerical simulation and parametric study are conducted to assess the effectiveness of the control system for reducing the wind-induced vibration of the bridge towers during construction. The numerical simulation results show that the MSPMD is practical and effective for reducing the along-wind response of the single column tower, can be installed in a small area of the tower, and complies with the time-variant characteristics of the bridge during its entire construction stage.     

浅层钻探技术在山区输电线路勘察中的应用研究

山区输电线路塔位区大多山高坡陡、植被发育、水源匮乏,导致钻探设备搬迁困难、用水不便,严重影响地质钻探工作开展。本文聚焦山区输电线路地质勘察工作需求,开展基于浅层钻探技术的系统性、集成性研究,引入了小口径（?46 mm）绳索取心技术,研制了新型高效的PDC钻头,优化了钻机提钻装置、循环系统、钻井液配方等,并在试验中得到验证。结果表明,无水钻进工艺适用于山区输电线路地质勘察,浅钻绳索取心技术可有效解决孔壁坍塌、钻进效率低等问题,升级后的钻机循环系统可进行钻井液循环钻进,通过优化钻井液配方可将取心率提高到85%以上,解决了山区输电线路地质钻探工作效率低、取心率低等问题。     

基于单个钻孔孔壁电视图像确定地下岩体结构面产状的普适数学方法

岩体结构面产状是影响岩体力学性质及工程稳定性的重要地质因素.从钻孔孔壁电视平展图上可较精确地提取结构面迹线上不共线三点的相对二维坐标(d, h),再利用空间解析几何理论确定其三维空间相对坐标(x, y, z),并求得结构面法向矢量.根据钻孔孔壁与坡面及结构面产状的空间几何关系,在保持原点不变的情况下,采用空间坐标变换的方法,将三维坐标系z轴和y轴分别转化为竖直方向z′和正北地理方向y′,并确定转化后坐标系空间的结构面法向矢量.再从结构面产状的定义出发,根据结构面法向矢量与结构面倾向、倾角的相关性,建立了一个空间几何模型,通过该模型可求得任意平直坡面上任一钻孔内局部岩体结构面的产状.      

WT－22型单桅杆液压伸缩钻塔

介绍了为煤田地质GZY-1200型全液压钻机设计的WT-22型单桅杆液压伸缩钻塔。重点讨论了塔的结构及工作原理、主体结构、起落机构与伸缩机构、钻塔的底部支承与锁定、绷绳以及液压系统的设计。