Texture-based identification of urban slums in Hyderabad, India using remote sensing data

This paper outlines a methodology to identify informal settlements out of high resolution satellite imagery using the concept of lacunarity. Principal component analysis and line detection algorithms were applied alternatively to obtain a high resolution binary representation of the city of Hyderabad, India and used to calculate lacunarity values over a 60 × 60 m grid. A number of ground truthing areas were used to classify the resulting datasets and to identify lacunarity ranges which are typical for settlement types that combine high density housing and small dwelling size - features characteristic for urban slums in India. It was discovered that the line detection algorithm is advantageous over principal component analysis in providing suitable binary datasets for lacunarity analysis as it is less sensitive to spectral variability within mosaicked imagery. The resulting slum location map constitutes an efficient tool in identifying particularly overcrowded areas of the city and can be used as a reliable source in vulnerability and resilience assessments at a later stage. The proposed methodology allows for rapid analysis and comparison of multi-temporal data and can be applied on many developing urban agglomerations around the world.     

基于光谱和纹理特征的ALOS影像土地利用信息提取

针对高分辨率遥感影像易于反映地物纹理特征的特点,综合利用地物的光谱和纹理特征进行分类,探讨适用于ALOS影像的土地利用信息提取方法。以川东丘陵地区影像为例,基于GLCM提取纹理信息,将提取的纹理特征向量采用赋权值法融合为一个综合纹理信息波段,然后采用面向对象法将其与光谱特征信息共同参与分类。与最大似然法的提取结果对比表明,考虑了纹理特征的面向对象分类方法能明显提高分类精度,Kappa精度提高了0.12;避免了椒盐现象,分割的地类边界具有更好的语义表达,更贴合地物实际分布特征;建筑用地和林地具有明显的纹理特征,而旱地纹理特征不明显。该方法不仅分出了6个基本地物类型,而且对于林地、建筑用地等类型还能进一步细分。     

基于判别空间条件熵加权的土地覆盖分类方法研究

针对遥感专题类别信息的机理问题,从土地覆盖参考数据的偏差程度对分类精度的影响角度,提出了一种基于判别空间条件熵加权的土地覆盖分类方法。引入判别空间模型概念,基于此模型生成土地覆盖数据类别,并分析了土地覆盖信息类别与数据类别的语义偏差出现的深层次原因;计算信息类别与数据类别的对应关系矩阵,据此得到二者的条件熵,实现对土地覆盖信息类别与数据类别的语义偏差的量化;根据信息类别与数据类别的条件熵计算修正判别变量的权重因子,实现基于判别空间条件熵加权的土地覆盖分类。采用一景SPOT-5影像进行分类实验,并利用同一地区的Landsat 5TM影像进行方法验证。实验表明,条件熵加权修正方法使土地覆盖分类精度有了显著提高,并对不同分辨率的遥感影像具有适用性。     

Progress in spectral studies of the FBS blue stellar objects

Spectral observations of 10 FBS blue stellar objects (BSO) with the OHP 1.93-m and BAO 2.6.m telescopes are reported, and overall progress in all the spectral observations and classifications of FBS BSO over 1987–2000 and in the classification of these objects based on all the accessible sources-- in all, 753 out of 1103 objects-- is discussed. Representative slit spectra for the major types of objects are presented and compared with digitized low dispersion spectra from the DFBS. The nature of the FBS objects is examined in terms of advances in the spectral studies. Two-color diagrams are constructed from the SDSS data and are used to find the regions occupied by the various types for further identification of objects of unknown type. Translated from Astrofizika, Vol. 52, No. 1, pp. 85–97 (February 2009).     

2007年12月至2008年2月T213、ECMWF及日本模式中期预报性能检验

为了解中期数值预报模式性能,提高中期预报水平,针对2007年12月至2008年2月T213模式96小时预报产品进行天气学检验,并与ECMWF、日本模式96小时预报性能进行了对比分析.结果表明,三个模式的96小时预报对亚洲中高纬地区大尺度环流形势演变和重大调整有较强的预报能力,对于转折性天气的预报有较强的指示意义.综合分析来看,ECMWF模式对西风指数、850hPa温度变化、500hPa环流形势及南支槽的预报误差最小,日本模式次之.     

Synoptic Typing and Its Application for Evaluating Climatic Impact on Air Quality in Urumqi

An automated procedure employing principal-component analysis and a two-stage cluster analysis was developed to classify the synoptic meteorological conditions prevailing over Urumqi, one of the most heavily polluted cities in the world. Six clusters representing different circulation patterns and air-mass characteristics were classified using surface- and upper-meteorological variables during the heating period from 2001 to 2008, and the relationships between synoptic clusters and air quality were evaluated. The heaviest air-pollution episodes occurred when Urumqi was in either an extremely cold, strong anticyclone or at the front of a migrating cyclone, both with light winds, wet surface air, and relatively dry upper air. Moderate pollution was seen when Urumqi was in the pre-cold/cold frontal passages with lower temperatures and light winds or moderate anticyclone with relatively warmer, drier air. When Urumqi was at the front of a migrating anticyclone or in a weak anticyclone with moderate winds and most warm, dry air, or in the cold/post-cold frontal passages with relatively strongly northerly airflows and precipitation, relatively good air quality could be seen. These results suggest that air pollution in Urumqi is very closely related to the synoptic meteorological conditions, which provides an important basis for not only the prediction and control of urban air-quality problems here but also for the analysis of the differential impacts of weather and pollution on human morbidity.     

基于人工神经网络的热带气旋路径预报试验

利用气候持续性因子,分别采用神经网络法及最小二乘回归法,建立西北太平洋地区12、24、36和48h热带气旋路径预报模型。通过对1992～2002年资料的试报,人工神经网络方法优于回归方法,且这种优势在预报时效较长时更明显。人工神经网络法48h的预报平均绝对误差比回归法减小27．56km,预报水平提高7％。     

利用大尺度环流确定2006年南海夏季风爆发日期

南海夏季风爆发最显著的特征就是南海地区西南风的突然增强和降水的明显增多,往往采用南海地区低层平均风场和(或)对流强度来判别南海夏季风的爆发日期。这种方法在大多数的年份是适用的,但是2006年由于0601号台风“珍珠”的介入,利用南海地区的区域指标来确定南海夏季风的爆发日期就略显不足。要解决以上的问题,必须从更大尺度上去想办法。利用经圈和纬圈环流可以较好地确定2006年南海夏季风的爆发日期。分析结果表明2006年南海夏季风爆发于5月16日(第4候)。     

国外前寒武纪铁建造的研究进展与有待深入探讨的问题

形成于早前寒武纪的铁建造,是一种富铁〔w(TFe)>15%〕的硅质化学沉积岩,其主要矿物组成是铁氧化物(磁铁矿和赤铁矿)及石英。根据铁建造的岩相学特征,将其划分为条带状铁建造和粒状铁建造;根据铁建造的沉积环境,将条带状铁建造划分为与火山岩有关的Algoma型和与细碎屑-碳酸盐岩有关的Superior型2种类型。铁建造的出现,起始于38亿年前,主要集中于28～18亿年,在18亿年之后有一个连续的缺失,但在8亿年左右因雪球事件而重新少量出现。Algoma型铁建造主要发育于中-新太古代,而Superior型则集中出现于古元古代;前者多形成于前寒武纪克拉通化之前,与海相火山活动和陆壳巨量增生密切相关,而后者多形成于克拉通化之后,与稳定发育的克拉通盆地和大气氧含量增加有关。Algoma型铁矿具有单个矿体规模较小、品位较低和多层发育等特征,而Superior型铁矿则具有单个矿体规模较大、品位较高、层位稳定等特征。由于铁建造在地质历史上大规模发育且不重复出现,所以,开展铁建造的研究不仅具有经济价值,而且具有重要的科学意义。铁建造的研究趋势是,在世界范围内进一步深化地球早期构造(地幔柱与早期板块构造)演化、水圈及大气圈组成与演化、地球早期生物活动,以及铁建造成因和时空分布规律等方面的研究。     

公路地基岩体质量分级研究

进行地基稳定性评价,关键在于查明地基结构形态和计算参数的确定。现有的勘查方法确定了地基的形态;本文从岩体质量分级入手,并提供了丰富的表格,为方便快速地确定各项参数提供了一种思路。