多源时序国产卫星影像的森林火灾动态监测

四川省木里县及周边林区是全国林火最为高发和易发区之一,近两年连续发生了扑火人员重大伤亡的事件。利用时序国产卫星影像、无人机影像和现场勘查数据等,从监测火灾蔓延时空过程的角度,对该区林火热点进行了动态监测,并分析了重点火场火灾发展过程,结果表明：以国产GF-4卫星影像为主,辅助以2 m/8 m光学卫星星座影像,可较好地监测林火热点;研究提出林火热点判定阈值为白天亮温值T≥360 K或夜间亮温值T≥330 K;监测发现了该区3月30日至4月6日间共6处火场的25次林火事件,并重点反演了①号木里和②号西昌火灾发展的时空过程。通过将卫星监测热点与现场勘查热点、无人机影像解译热点对比,表明在火灾早期和中期卫星林火热点监测精度可达89%。建议利用时序国产多源卫星影像对该区林火进行持续监测,并结合权威部门现场勘查数据适时发布预警信息,避免造成重大生命财产损失。     

基于亮度恢复模型的Landsat 8数据山区阴影去除

遥感影像中的山区阴影覆盖范围广、去除难度大、影响信息提取精度,通过最大值选取函数(Max)与波段比值构建阴影检测模型(Shadow Detection,SD),结合坡度因子提取影像中山地阴影区域,并通过网格随机布置验证点验证精度;通过地面阴影亮度与阴影像元亮度变化规律,拟合影像阴影区亮度曲线模型,结合导函数,建立亮度恢复模型。对长汀县域的Landsat 8影像处理,获得的结果显示:山区阴影的提取精度为99.06%,Kappa系数为98%;聚类显示恢复区与非阴影属于同一类型;通过亮度恢复模型计算得出各个波段的阴影区域像元亮度平均值提升13%,标准差降低80%,距离系数降低96%,较ATCOR_3方法,像元亮度平均值提升6.7%,标准差降低73.7%,距离系数降低88.3%,较一元线性恢复方法,像元亮度平均值降低1.8%,标准差提升6.7%,距离系数降低90%。该方法在恢复山区阴影的过程中实现了不替换阴影像元,不干扰非阴影像元,能较好地保留阴影像元的光谱与亮度特征。     

NOAA／AVHRR资料在监测土壤盐渍化程度中的应用

一、资料来源 NOAA/AVHRR资料由国家气象局卫星气象中心提供。 Landsat TM影像由中国科学院卫星地面接收站提供。土壤盐分资料由地面测点测得。二、波段与时相的选择 1988、1989年,为本研究的进行,在天津市静海县建立土壤盐碱地监测基点,进行土壤盐渍化的地面光谱测定,使用仪器为RS—Ⅱ型四通道野外光谱仪和红外辐射仪,并在1988     

气象卫星"风云二号"04星即将在西昌卫星发射基地发射升空

据新华网消息 ,中国自行研制的“风云二号”气象卫星0 4星已完成卫星总装和相关测试工作 ,目前正整装待发 ,一切顺利的话 ,预计将于 10月左右在西昌卫星发射基地发射升空 ,并向世界各国提供卫星云图。据介绍 ,“风云二号”0 4星是一颗地球同步轨道静止气象卫星 ,将定点在东经 10 5°的赤道上空 ,从距地面 36 0 0 0km的高空对亚太地区进行观测。除了可以获得红外云图和水气分布图外 ,还增加了对森林火灾、草原火灾、大雾天气和沙尘暴的观测能力。发射“风云二号”0 4星 ,主要是为了替代超时“服役”的“风云二号”C星。“风云二号”C星专门…     

Landsat 8影像像元地理坐标计算

在遥感卫星数据处理中,计算影像中像元对应地面点的地理坐标不仅是遥感影像数据编目的主要工作之一,同时也是各级几何校正的基础,其计算精度直接影响数据产品处理的几何精度.本文在充分了解Landsat 7卫星和SPOT5卫星像元地理坐标计算算法的基础上,对USGS提出的Landsat 8卫星像元地理坐标计算算法进行了系统性整理和研究,并比较了3种传感器间扫描方式和探测器排布的差异造成计算方法的差异,最后以一景Landsat 8的模拟数据为样本,以GLS2005地面控制点库为参考,将本文介绍算法得到的坐标与控制点库坐标作了对比分析,结果验证了该算法的有效性.     

融合无人机机载激光雷达的变形监测技术研究

为提高变形监测精度，提出一种融合无人机机载激光雷达的变形监测方法。方法通过采用点云差值法(Point cloud difference, PCD)计算两期待监测区域的地表下沉数字表面模型(Digital Surface Model, DSM)差值，并基于无人机机载激光雷达数字正射影像图(Digital Ortho Map, DOM)计算地表水平移动矢量，分别实现了地表下沉监测和水平移动监测。仿真结果表明，所提方法可通过地表下沉监测和水平移动监测，有效、可靠地监测地表变形。在整个监测过程中，像控点精度对变形监测精度具有重要影响，随着像控点中误差的增加，下沉监测与水平移动监测误差增加，误差分布区间占比减小；当平面中误差和高程中误差均为6 cm时，下沉监测误差和水平移动监测误差分别为0.3 cm和0.2 cm,有效提高了变形监测精度，满足了变形监测误差需求，具有一定的实际应用价值。     

环境减灾卫星影像森林火灾监测技术方法研究

森林火灾是世界性的、频繁发生的重大自然灾害。随着国内外航天科技的迅猛发展,卫星遥感技术特别是红外卫星遥感已成为森林火灾监测的一种有效手段。我国的环境一号卫星A、B星(简称HJ-1A卫星、1B卫星)于2008年9月成功发射,其中的HJ-1B卫星搭载了红外多光谱相机,在森林火灾监测方面具有得天独厚的优势,可在早期的火灾发现、中期的灾害跟踪、后期的灾害损失评估中发挥重要作用。本文主要分析了环境减灾卫星在森林火灾监测方面的优势,对环境减灾卫星森林火灾监测技术和方法进行了研究。     

热红外静止卫星地震监测系统综合技术研究

基于Windows NT服务和Socket套接字程序整合设计了卫星数据处理后台管理服务系统,从底层开始自主开发了卫星数据准实时自动处理系统。通过该系统避免了大量的人工操作,获得了大量的、连续的、覆盖全国的热红外无云遥感影像库,能对任意选定的监测区进行热红外亮温动态跟踪和异常警示。通过对地震热红外卫星监测业务运行系统的研究和开发,为地震热红外研究提供了实用的技术手段和技术基础,为卫星热红外等多源遥感卫星及地面应用系统,天地一体化观测数据处理技术提供了经验。     

MODIS浒苔遥感监测误差分析研究

近年来,我国沿海浒苔灾害频发,影响日趋严重,MODIS-TERRA/AQUA等中低分辨率卫星遥感影像成为浒苔遥感监测最主要的数据源之一。但低分辨率影像存在大量混合像元,导致浒苔提取误差。本文先从理论上分析了植被指数算法的非线性对浒苔信息提取的影响,发现像元中浒苔覆盖比例为0.2～0.4时,NDVI最大,会有0.8的偏差,且浒苔越厚误差越大。然后以环境减灾卫星(HJ-1A/B)作为真实值,对MODIS浒苔监测误差进行定量分析。结果表明:MODIS影像难以兼顾大块聚集和零散分布的浒苔,业务化监测中提取面积可能会被夸大21.88%,在面积准确的情况下,也会有21.67%的浒苔信息被错误提取。本文最后提出通过选择两个阈值来解决此问题。     

山区可见光—近红外遥感影像浓密植被暗像元自动识别方法研究

暗目标法是目前气溶胶光学厚度遥感反演中应用最为广泛的方法,浓密植被暗像元的识别是暗目标法的基础。针对可见光—近红外影像缺少中红外波段难以有效识别浓密植被暗像元的问题,引入红波段直方图阈值法识别山区可见光—近红外影像的浓密植被暗像元。该方法利用浓密森林像元在可见光波段反射率低的特点,通过搜索红波段直方图的最小峰值自动识别浓密植被暗像元。试验中选取Landsat TM影像前4个波段利用红波段直方图阈值法识别可见光—近红外影像的浓密植被暗像元,并与在中红外波段影像和可见光—近红外影像中广泛应用的两种暗像元识别方法进行对比分析,探讨红波段直方图阈值法的有效性,最后将该方法应用于环境减灾卫星(HJ-1)CCD影像的暗像元识别和气溶胶反演。实验结果表明:红波段直方图阈值法明显优于常用的可见光—近红外影像暗像元识别方法,识别精度接近传统的中红外波段影像识别方法,相似度指数小于2和小于3的暗像元分别为83.12%和93.48%。该方法为山区可见光—近红外影像浓密植被暗像元自动识别提供了一种新的适用方法,识别结果能够满足暗目标法反演气溶胶光学厚度的要求。     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.