Texture classification of Mediterranean land cover

Maximum likelihood (ML) and artificial neural network (ANN) classifiers were applied to three Landsat Thematic Mapper (TM) image sub-scenes (termed urban, agricultural and semi-natural) of Cukurova, Turkey. Inputs to the classifications comprised (i) spectral data and (ii) spectral data in combination with texture measures derived on a per-pixel basis. The texture measures used were: the standard deviation and variance and statistics derived from the co-occurrence matrix and the variogram. The addition of texture measures increased classification accuracy for the urban sub-scene but decreased classification accuracy for agricultural and semi-natural sub-scenes. Classification accuracy was dependent on the nature of the spatial variation in the image sub-scene and, in particular, the relation between the frequency of spatial variation and the spatial resolution of the imagery. For Mediterranean land, texture classification applied to Landsat TM imagery may be appropriate for the classification of urban areas only.     

人造卫星数据库管理系统中ORACLE FORMS的应用

ＯＲＡＣＬＥ ＦＯＲＭＳ是ＯＲＡＣＬＥ数据库系统应用程序重要的开发工具之一,它具有良好的窗口,模拟块以及触发器等功能,同时它作为ＯＲＡＣＬＥ大家族中的一员,与ＯＲＡＣＬＥ的其他应用工具又是分不开的。本文结合实例详细地介绍了ＯＲＡＣＬＥ ＦＯＲＭＳ在开发人造卫星数据库管理系统中的应用。     

参数调整对气象预测的B-P网络模型性能的影响

为了探索ＢＰ网络的参数调整特性,进行了参数α、β的选取对ＢＰ算法的收敛速度和模型的稳定性的影响研究。通过ＢＰ网络用于气象预测建模的参数调整个例分析表明：参数α、β的取值对ＢＰ模型的稳定性无显著影响,但参数值的调整尤其是β值的调整对建模的收敛速度有明显的影响。     

广州莲花山的人工丹霞地貌和旅游开发

通过实地考察,概述广州番禺莲花山与粤北丹霞山地质地貌的异同,从丹霞地貌角度阐述这座古石矿场“人工无意夺天工”形成的陡崖,岩洞,石墙,石巷,岩湖,石柱,石门,石桥等人工丹霞奇观,并对这座以全国罕有古石矿场为主景的莲花山旅游区的进一步开发,提出了讨论意见。     

同时满足多个阻尼反应谱的人造地震动时程合成

应用Ｍ．Ｈｉｒａｓａｗａ和Ｍ．Ｗａｔａｂｅ（１９９２）提出的方法,进行了相应的数学推导：即以满足某个阻尼比的反应谱的人造地震动作为初始时程,采用奇异值分解法,通过解线性方程组求出校正时程,并多次叠以逐步辐近     

陕西省人工神经元网络降水年,季度预报系统

利用Ｂ－Ｐ人工神经元网络进行了陕西省年度,季度降水预报试验,提出了利用０－１模型解决多等级预报问题的方法,并建立了年度,季度等级预报模型,经过试验,表明该方法预报效果良好,最后对模式在应用中的一些问题及目前其它预报模型的差异等进行了讨论。     

人工增雨试验中的反效果问题

该文对人工增雨试验中出现的反效果（减雨）现象及其发生的条件和原因作了概要的评述和分析。根据实例分析,指出人工增雨作业中不适当的催化对象、不适当的催化剂和催化剂量以及不适当的催化部位和催化时机都有可能导致无效或减雨的反效果。在开展人工增雨作业时,应力求在作业有关的各环节提高科学性、减少盲目性,以提高人工增雨实效。文章还简要探讨了人工削弱局地暴雨的可能性,指出这是一个值得认真探索的具有重大潜在社会和经济效益的研究领域。     

模糊控制在直流变频空调器中的应用

从直流型变频空调器的特点及控制要求出发,提出了模糊控制系统的结构,讨论了直流变频空调器的模糊控制算法.对控制器的性能(主要是鲁棒性)进行了详细的分析,对所采用的模糊控制算法在Matlab平台下进行了仿真,作为比较同时给出了其他常用算法的仿真结果.     

ISA accelerometer onboard the Mercury Planetary Orbiter: error budget

We have estimated a preliminary error budget for the Italian Spring Accelerometer (ISA) that will be allocated onboard the Mercury Planetary Orbiter (MPO) of the European Space Agency (ESA) space mission to Mercury named BepiColombo. The role of the accelerometer is to remove from the list of unknowns the non-gravitational accelerations that perturb the gravitational trajectory followed by the MPO in the strong radiation environment that characterises the orbit of Mercury around the Sun. Such a role is of fundamental importance in the context of the very ambitious goals of the Radio Science Experiments (RSE) of the BepiColombo mission. We have subdivided the errors on the accelerometer measurements into two main families: (i) the pseudo-sinusoidal errors and (ii) the random errors. The former are characterised by a periodic behaviour with the frequency of the satellite mean anomaly and its higher order harmonic components, i.e., they are deterministic errors. The latter are characterised by an unknown frequency distribution and we assumed for them a noise-like spectrum, i.e., they are stochastic errors. Among the pseudo-sinusoidal errors, the main contribution is due to the effects of the gravity gradients and the inertial forces, while among the random-like errors the main disturbing effect is due to the MPO centre-of-mass displacements produced by the onboard High Gain Antenna (HGA) movements and by the fuel consumption and sloshing. Very subtle to be considered are also the random errors produced by the MPO attitude corrections necessary to guarantee the nadir pointing of the spacecraft. We have therefore formulated the ISA error budget and the requirements for the satellite in order to guarantee an orbit reconstruction for the MPO spacecraft with an along-track accuracy of about 1 m over the orbital period of the satellite around Mercury in such a way to satisfy the RSE requirements.     

大数据智能时代地图学课程内容改革探索

为了适应当前智能时代大数据的特点和地图应用的发展,本文结合当前地图学课程内容设置现状,分析在大数据时代地图学教学的特点,多源地理信息的参考体系差异、多维度地理信息高效可视化、多尺度表达的灵性化、地图用户需求的多样化等对地图学教学提出的新要求,在此基础上,结合地图学课程教学的理论与实践目标,提出在地图数学基础、地图可视化技术、地图综合和地图分析等进行课程教学内容改革的主要思路,增设新型坐标系知识、多维动态可视化技术、地图应需综合的多尺度表达方法、全息地图理论等主要知识点,并给出了课程实验教学改革的设计。