河北省火箭人工增雨效益分析

针对河北省火箭人工增雨作业的实际情况,从火箭作业系统的选取、火箭作业点布设、适宜火箭人工增雨作业的云层条件、合适的作业部位和时机选择、火箭人工增雨实施作业情况和作业量分析等入手,采用区域对比方法分析了河北省2000~2004年火箭人工增雨作业的效果和效益,得出了河北省火箭人工增雨作业的总增雨量和增雨效益,并根据河北省2000~2004年的总投资情况计算出投资效益比为1:46。     

Persistent Features of Drought Strength in North China and Its Prediction

1. Introduction Drought disasters occur frequently in North China, with droughty extension being the widest, droughty intensity the most serious and lasting time the longest. In particular, the serious drought has threatened agriculture extremely in recent years, as such has influenced economy, ecosystem, and even daily life of people. The drought in North China is not only the vital research subject for meteorologists, but also one of the issues concerned for government. Therefore, finding …     

正射影像上阴影和遮蔽的信息处理方法研究

分析了正射影像上阴影和遮蔽现象的利弊双重性特点 ,讨论了正射影像上阴影和遮蔽处理的原则 ,简单介绍了基于光照函数分析和基于色彩空间分析的彩色航空影像阴影信息增强方法以及基于整体变分模型和基于纹理匹配的影像缺损信息补偿方法。试验表明 ,所提出的正射影像上阴影和遮蔽的信息处理方法是有效的     

Galileo系统指标和导航信号结构

介绍了Galileo系统的工作指标、载波频率、信号体制和导航数据格式；并与GPS、GLONASS系统进行了比对研究，对于设计我国自主卫星导航系统具有参考价值。     

多普勒雷达图象资料在人工增雨决策指挥中应用研究

利用2000-2002年山东省春、秋、冬三季17次稳定性降水过程的多普勒天气雷达资料进行统计分析，研究山东省大范围稳定性降水的速度回波演变情况，得出系统加强、维持、消散的图象特征。当整层为暖平流，上层为西南气流且有明显的垂直风切变时，系统维持时间较长；当低层风场出现暖平流加辐合特征相结合时，系统加强且持续时间较长，上述两种流场特征适宜实施飞机人工增雨作业。当整层出现冷平流或主体为冷平流时，系统开始减弱，且移速较快，持续时间较短，不适宜实施人工增雨作业。     

图像分辨率增强的偏微分方程方法

讨论一种新的图像分辨率增强的偏微分方程模型。新模型利用图像为分片连续的二维曲面的先验信息,采用非线性扩散方程对基于最近邻方法放大后的图像进行光滑以消除因放大引起的“块状”效应,同时在迭代过程中加入插值条件使处理后的图像能较好的保留边缘,由此构造出基于偏微分方程的图像分辨率增强模型和相应的迭代算法,使图像的分辨率增强到亚像元级。遥感图像的仿真计算结果表明,该方法具有比现有方法更高的峰值信噪比和更高的边缘保护指数。     

小波变换在遥感数字图像处理中的作用

简要介绍了小波的基本概念、特点，以及小波变换在数字图像压缩、图像消噪、图像增强以及影像融合等遥感数字图像处理中的作用。     

强场源TEM测量仪器和在大型矿山接替资源勘探中的应用研究

针对矿山噪声强、要求勘探深度大的特点,应用强场源TEM测量仪器,采用双发射信号同步叠加增大发射磁矩,即通过增大发射电流和合理选择发射回线边长,提高瞬变信号晚延时的信噪比的方式提高有效勘探深度。在安徽铜陵凤凰山铜矿的实际勘探中,采用吉林大学研制的 2个ATEM-Ⅱ型发射机同时工作,将发射电流由 2. 4A增大到 38 .5A,晚延时瞬变信号的信噪比由 0 .275提高到2. 93,有效探测深度达到 650m以上,表明强场源TEM测量仪器在寻找大型矿山接替资源勘探方面具有较好的发展前景     

用于超宽带信号数据采集的高精度可编程定时器研究

超宽带信号的数字化在很大程度上取决于采样时刻的准确性，因此是否具有高精度的可编程定时器是实现超宽带信号数据采集的关键。本文基于斜波发生器原理实现了高精度可编程定时电路，可编程计数范围为16bit，实际最小定时单位达8ps，折合采样频率高达50GHz，迄今为止尚未有关于同样指标产品的报道。该定时器已应用于作者研制的地质雷达信号数据采集系统中，取得了很好的实际应用效果。     

The boundary layer characteristics in the heavy fog formation process over Beijing and its adjacent areas

By utilizing the Atmospheric Boundary Layer (ABL) observational data made available from the project "973" under the auspices of the Ministry of Science and Technology of the People's Republic of China - entitled the Beijing City Air Pollution Observation Field Experiment (BECAPEX), including the measurements by a wind profiler, captive airships, tower-based boundary layer wind and temperature gradient observational instruments (ultrasonic anemometers and electronic thermometers), air composition samplers, conventional upper-air, surface and Automatic Weather Stations (AWS) observations, this paper herewith analyzes, in a comprehensive manner, the occurrence of a heavy fog event over Beijing in February 2001, including its formation, development, persistence, dynamic and thermodynamic features as well as evolving stratification structures within the boundary layer at different stages. The results suggested: (i) as a typical case of urban heavy fog, before the fog onset over Beijing, a temperature inversion existed in the lower atmosphere, the smokes and the pollutants like SO2 and NO2 had been accumulated at a lower level. Proceeding the fog event, with the increase of SO2 and NO2 concentrations, condensability increased sharply. On the contrary, during the fog process, with increasing condensability, SO2 and NO2 concentrations decreased. This indicated that, acting as condensation nucleus, these accumulated pollutants were playing a key role in catalyzing the fog condensation. (ii) By analyzing mean gradient-, pulsation- and turbulence-distribution patterns derived from the wind measurements taken by the aforementioned tower-based instruments, they all indicated that about 10 hours before the fog onset, a signal foretelling potential strong disturbances in the lower boundary layer was detected, and a significant rise of both mean and disturbance kinetic energies was observed, revealing that the low-level wind shear was strengthened before the fog onset, consequently creating a favorable condition for the outbreak of turbulences. This strong signal seemed to be very meaningful in monitoring and predicting fog occurrence and its development. (iii) Once the fog was in shape, its condensation feedback effects tended to lift the height of temperature inversion layer within the mid and upper levels of the lower atmosphere, which in return determined the fog persistence and restructuring process.