串行传输线同步信号辐射发射模型研究

在同步信号自身频谱特性研究基础上,利用天线效应和极子积分方法,建立了串行传输线同步信号的单线辐射发射模型。分析提出传输线上电流分布的近似驻波状态,并以此为条件推导出串行传输线辐射发射模型的近似解,通过对模型近似解的进一步分析,得到串行同步信号谐波分量的辐射发射规律,给出了串行传输线同步信号辐射发射极值频率、基波频率和同步信号占空比间确定的函数关系。针对串行传输线辐射发射的实验测试结果表明,所建模型可以准确描述串行传输线同步信号的电磁信息辐射泄漏特性。同时,与其他模型对比分析可知,该模型对串行传输线同步信号时频域辐射泄漏规律的刻画更为准确全面。

基于ASTER GDEM的黑龙江省地形起伏度分析

地形起伏度是描述地貌形态的重要指标,反映了研究区域内地势起伏特征。以黑龙江省为研究区域、以30 m分辨率的ASTER GDEM(先进星载热发射和反射辐射仪全球数字高程模型)数据为基础,在ArcGIS平台上利用领域分析法分析不同窗口大小下的地形起伏度,通过均值变点法得出最佳统计单元面积为0.396 9 km^(2)。在此基础上对黑龙江省地势起伏度进行分析。结果表明黑龙江省地形起伏可分为4类,主要以台地、丘陵为主,平原占比次之。

东秦岭地貌形态等级体系的构建与空间特征分析

利用分辨率为30 m的先进星载热发射和反射辐射仪全球数字高程模型数据,选取绝对高程、相对高程构建东秦岭高程形态等级体系;选取坡度、地形起伏度、地面粗糙度构建东秦岭起伏形态等级体系;采用GIS空间叠加法,构建东秦岭地貌形态等级体系,对东秦岭的地貌形态的空间特征进行分析.结果表明,东秦岭高程形态分为低山、低中山、中山、中高山、高山5类,起伏形态分为微起伏、小起伏、微中起伏、中起伏、微大起伏、大起伏6类;从东秦岭地貌形态等级体系提取出25种地貌形态,主要以微中起伏的低中山、中山为主,分别占全区面积的12.97%、12.05%;其中,以洛南-商州-丹凤-商南-郧西为界,可将东秦岭分为东、西两部分.

IMPACT OF CLOUD DROPLETS SPECTRAL UNCERTAINTY ON MESOSCALE PRECIPITATION

1 INTRODUCTION Cloud radiation is one of the most important and indefinite factors in atmospheric radiation. As shown in a comparative study by Cess et al. with a climate model, differences can be very large in the outcome of varying schemes of cloud parameterization. It is therefore of great significance to have a relatively accurate scheme of cloud parameterization for the atmospheric radiative transfer process. According to the Mie＇s scattering theory, the scale parameter of the particulate has a very important effect on its optical property. It is then seen that the number concentration and size distribution of cloud droplets play an important in the determination of the optical properties of cloud droplets.

The definition analyses of radiation temperature measurement area

In the research of primary spectrum pyrometry, this paper discussed the definition problem of radiation temperature measurement area based on the measurement coordinates. For the linear spectrum emissivity model and improved monotonic spectrum emissivity model, the characteristics of radiation temperature measurement area restricted by the measurement coordinates were theoretically analyzed, through the investigations of the temperature and emissivity coordinate axes. Choosing the specific primary spectrum pyrometer as an example in applications, the theoretical area of radiation temperature measurement of this pyrometer was given and it was verified through blackbody experiments. The discussions of this paper will provide the necessary foundation for the theory research development of primary spectrum pyrometry and the realization of technical applications.

ASTER GDEM格式地形数据在Radio Mobile仿真软件中的应用探索

结合地理信息技术(Geographic Information Sciences,GIS)的计算机仿真,已经成为无线电传播信道分析的重要手段之一。仿真软件“移动无线电”(Radio Mobile)可以对指定地形下的无线电波传播过程进行数值模拟,直接识别并导入多种地形数据,但并不包括当今精度最高且国内广为流行的免费地形数据——先进星载热发射和反射辐射仪全球数字高程模型(Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model,ASTER GDEM),其精度可达30 m。因此,介绍一种如何将ASTER GDEM的数据读入Radio Mobile的处理方法。首先,利用GIS软件Global Mapper将ASTER GDEM压缩包数据转换为按照经纬度排列的DTED数据;其次,将DTED数据整理到以经度命名的文件夹内,每个文件按照纬度命名;最后,在Radio Mapper的地图属性设置中输入待仿真地域的经纬度,完成地形数据的导入。在此基础上,针对某一指定经纬度导入地形场景,利用Radio Mobile对电磁波的路径损耗做了初步的数值仿真。