查询词典 downburst

The authors discuss a new numerical simulation method of the downburst wind loads on the basis of the previous research. Firstly, the wind speed is expressed as the sum of an instantaneous mean wind speed and an amplitude-modulating non-stationary fluctuating wind speed. Secondly, a new method based on the modified Osegguera and Bowles/Vicroy model to simulate the mean wind is presented and the fluctuating wind is simulated by a modified spectral representation method.

在将下击暴流风速表达为时变的平均风速和调制的非平稳脉动风速之和的前提下，本文采用基于改进的OBV模型Oseguera and Bowles/Vi-croy(OBV的方法来模拟平均风速，其平均风速直接由改进的OBV模型表达，而不同于已往研究中将平均风速表达为竖向风剖面与时间函数的乘积，并采用结合快速傅里叶变化的谐波叠加法来模拟调制的非平稳脉动风速。

A wind tunnel for thunderstorm downburst was well designed by taking into account the low-speed uniflow wind tunnel design criteria, andan adjustable plate was made to simulate the ground.

鉴于雷暴冲击风试验装置的特殊性以及与低速直流风洞的共通性，参考低速直流风洞的设计方法设计完成了试验装置的洞体结构，并制作了具有调节功能的平板来模拟地面。

Thunderstorm downburst wind tunnel has the particularity and the intercommunity with a low-speed uniflow wind tunnel. A wind tunnel for thunderstorm downburst was well designed by taking into account the low-speed uniflow wind tunnel design criteria, andan adjustable plate was made to simulate the ground.

鉴于雷暴冲击风试验装置的特殊性以及与低速直流风洞的共通性，参考低速直流风洞的设计方法设计完成了试验装置的洞体结构，并制作了具有调节功能的平板来模拟地面。

The unsteady numerical simulation is helpful to understand the dynamics of downburst wind.

非定常的数值模拟将有助于更好地理解下击暴流风的动力特征。

The research confirmed that the wind field characteristics of downburst are quite different from boundary layer winds.

研究证实，下击暴流风具有同常规的大气边界层近地风完全不同的风场特征。

As a kind of high intensity winds, the downburst usually comes forth during thunderstorm and has caused numerous structural failures around the world.

作为自然界的一种强风荷载，雷暴天气产生的下击暴流风在世界范围内造成了大量工程结构物的破坏。

Investigation on tower collapses of 500 kV Renshang 5237 transmission line caused by downburst .

华东电网500 kV任上5237线飑线风致倒塔事故调查分析。

It was pointed that the study of downburst wind loads would provide the basis and guides for constructing the next wind tunnel emulating thunderstorm environment and downburst-resistant design of transmission tower-line systems; simultaneously it would give an important reference to both the design and implementation of wind-induced vibration control of transmission tower-line systems.

指出了对下击暴流风荷载的研究将为我国建造模拟雷暴风环境的新一代风洞实验室和输电塔线体系的抗下击暴流提供理论基础和设计指导，同时为输电塔线体系的风致振动控制设计与实现提供重要的参考。

Results indicate that the height of maximum horizontal wind velocity is correlative with the horizontal position. The downburst intensity and jet diameter have rather small effects on the test results in a certain range. Nevertheless, the jet height and obliquity can affect the flow field of downburst significantly.

研究结果表明：最大水平风速出现的高度与其水平位置有关；射流速度V与射流直径D在一定范围内对试验结果影响不大；射流高度h与入射倾角α对冲击风的流场有明显影响。

Careful analysis on NBE can facilitate nowcasting of severe weather events and further understanding of their evolution. After detailed study on three cases concerning with NBE, it is concluded:(1) NBE triggered by fast moving echo in upstream is an important indication of disastrous wind;(2) NBE can develop into severe storm under proper conditions. There are often two stages during this kind of growing: the first is developing of initial echo, the second is snap growing of echo core;(3) Doppler radar reflects outflow of downburst as a nearly ringed NBE. Inside look on downburst can be obtained combining NBE with other data.

文章结合发生在上海的3次强对流天气个例，详细分析了弱窄带回波在分析和预报强对流天气中的作用，得出以下结论：（1）上游移动强回波的出流边界导致的弱窄带回波是大风预警的重要判断参考；（2）在合适的层结状态和抬升条件下，弱窄带回波会强烈发展，并导致局地雷雨大风，这类强对流天气的发展有两个比较重要的阶段：弱窄带回波上初始回波的发展和回波跃增；（3）下击暴流造成的地面出流在雷达回波上表现为近似圆弧的弱窄带回波，这种弱窄带回波与其他雷达观测特征以及地面观测相结合，有助于对产生下击暴流的对流云的发生发展过程进行细致分析。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。