基于光谱归一化的马尾松LAI遥感估算研究

通过对比不同传感器间光谱响应函数的差异,研究基于光谱响应函数的不同传感器相似波段的归一化方法,探讨归一化后植被指数在马尾松叶面积指数（LAI）估算中的应用。以某一传感器为基准,根据波段总辐射率比值关系将其他卫星传感器归一化为基准传感器,然后计算其植被指数,建立LAI反演模型。为验证方法可行性,选取永安地区2008年3月获取的BJ-1CCD、IRS-P6LISS3和MODIS数据作为研究对象,根据三者的光谱响应函数差异,将BJ-1CCD和IRS-P6的LISS3的红光和近红外波段归一化为MODIS的相应波段,并分别计算归一化前后的NDVI值。结果表明归一化后不同传感器的植被指数关系与理想的关系y=x更加接近。利用归一化后的IRS-P6影像的NDVI反演马尾松LAI,并将其应用于MODIS和BJ-1传感器,得到归一化后不同传感器的植被指数值基本相等,表明归一化以后的植被指数应用于LAI的估算具有一定的普适性,能适用于多种传感器。     

基于宽波段和窄波段植被指数的草地LAI反演对比研究

叶面积指数是一个重要的植被生理生态参数,为探讨不同植被指数反演叶面积指数的可行性,基于同空间分辨率不同光谱分辨率的HJ\|1B CCD1和Hyperion遥感影像数据,以内蒙古自治区赤峰市克斯克腾旗贡格尔草原为研究对象,选取几种常见宽波段植被指数和高光谱窄波段植被指数并结合4种常用回归模型,比较分析了不同植被指数反演叶面积指数的精度。结果表明:对于全部植被指数而言,PVI、MSAVI等综合考虑了土壤、环境等因素的植被指数较传统植被指数NDVI、RVI反演草地LAI精度更高。通过对比发现,在反演草地LAI方面,窄波段植被指数比宽波段植被指数表现出明显的优势。其中,窄波段垂直植被指数PVI验证模型的确定性系数R²为0.65,均方根误差RMSE为0.15,说明实测LAI和模拟LAI值之间具有较好的变化一致性。最后基于Hyperion影像和窄波段垂直植被指数PVI的估算模型生成研究区叶面积指数空间分布图。     

基于无人机高光谱数据的玉米叶面积指数估算

无人机高光谱遥感是低成本、高精度获取精细尺度农作物生物物理参数和生物化学参数的新型手段，以此快速反演叶面积指数（Leaf Area Index, LAI）对作物长势评价、产量预测具有重要意义。以山东禹城市玉米为研究对象，利用PROSAIL辐射传输模型模拟玉米冠层反射率获取LAI特征响应波段结合相关性定量分析获取对LAI变化最为敏感的波段，并以此计算6种植被指数（Vegetation Index,VI），利用6种回归模型分别对单一特征波段和VI进行反演建模，以实测LAI评定模型精度。研究表明，光谱反射率中516、636、702、760和867 nm等波段对LAI变化最为敏感，以此建立的单一特征波段反演模型预测LAI精度R2为0.44~0.58；RMSE为0.16~0.18，其中636 nm建立的模型(LAI=21.86exp(-29.47R₆₃₆))相比其他反演模型预测精度较高（R2=0.58，RMSE=0.16）；6种植被指数与LAI高度相关，相关性系数R ²为0.85~0.86，以此建立的反演模型相比单一特征波段反演模型精度有所提高，R2为0.66~0.72，RMSE为0.12~0.14；其中mNDVI构建的LAI估算模型（LAI=exp(2.76~1.77/mNDVI))精度最高（R2=0.72，RMSE=0.13）。无人机高光谱遥感是快速、无损监测农作物生长信息的有效手段，为指导精细化尺度作物管理提供依据。     

MODIS水体指数模型(CIWI)研究及其应用

本文通过分析MODIS与水体识别相关的1~7波段地物光谱图像特征及相关水体指数模型的识别效果,提出了新的水体指数模型(CIWI)。该模型采用植被指数与近红外波段7的进一步组合,有效地解决了水体与云、植被、城镇等其他信息的分离问题,特别是明显地增强了水体与城镇的分离度,实现了水体信息的有效提取。通过应用2004~2005年的MODIS资料对广西贵港市平龙水库进行水体信息遥感监测表明,CIWI水体指数模型优于其他水体指数模型。     

水稻叶面积指数的多光谱遥感估算模型研究

LAI是生态系统研究中最重要的结构参数之一,它是估计多种植冠功能过程的重要参数。通过两年的水稻田间试验,使用美国ASD背挂式野外光谱辐射仪(ASDFieldSpec),获取1999～2000年两年晚稻整个生育期的光谱数据,采用计算机测算图斑面积法测定LAI;根据已有的卫星传感器通道波段(MSS、RBV、SPOT、TM、CH)和它们的组合(比值植被指数、归一化差植被指数),以及具有物理意义的光谱区域(蓝区、绿区、黄边、红光吸收谷、红边、紫区、可见光区、近红外区、全部波段)等共有27个变量构建多光谱变量组,采用5个单变量线性与非线性拟合模型,用1999年试验数据为训练样本,建立水稻LAI的多光谱遥感估算模型。结果表明:适用于水稻LAI估算的多光谱变量是植被指数变量好于波段变量;RVI与NDVI比较,RVI好于NDVI。用2000年试验数据作为测试样本数据,对其精度进行评价和验证,非线性模型的精度高于线性模型的精度,其中以SPOT3/SPOT2为变量的对数模型,拟合R2与预测R2达到了最大,其RMSE和相对误差(%)为最低,因此,认为它是估算LAI的最佳模型。
     

玉米叶面积指数与高光谱植被指数关系研究

探讨以不同的植被指数建立的高光谱模型对玉米叶面积指数LAI的反演精度。实测不同水肥耦合作用下，玉米冠层的高光谱反射率与叶面积指数（Leaf Area Index）数据，采用高光谱红光波段（631~760 nm）与近红外波段（760~1 074 nm）逐波段构建NDVI、RVI、DVI、TSAVI、PVI植被指数，分别找出与LAI具有最佳相关性波段组合的植被指数，建立玉米LAI估算模型。结果显示，与LAI具有佳相关性的波段组合分别是NDVI（R760，R990）、RVI（R760，R1001）、DVI（R677，R1070）、TSAVI（R 760，R 975）、PVI（R658，R966），它们反演玉米LAI的确定性系数分别：R²>0.72、R²>0.74、R²＝0.95、R²>0.79、R²>0.95。结果表明，在玉米的整个生长季的47个样本中，通过PVI和DVI方式建立的遥感估算模型能够较为准确地估算玉米LAI，TSAVI次之，NDVI、RVI稍差。     

基于无人机高光谱数据的玉米叶面积指数估算

无人机高光谱遥感是低成本、高精度获取精细尺度农作物生物物理参数和生物化学参数的新型手段,以此快速反演叶面积指数（Leaf Area Index, LAI）对作物长势评价、产量预测具有重要意义。以山东禹城市玉米为研究对象,利用PROSAIL辐射传输模型模拟玉米冠层反射率获取LAI特征响应波段结合相关性定量分析获取对LAI变化最为敏感的波段,并以此计算6种植被指数（Vegetation Index,VI）,利用6种回归模型分别对单一特征波段和VI进行反演建模,以实测LAI评定模型精度。研究表明,光谱反射率中516、636、702、760和867 nm等波段对LAI变化最为敏感,以此建立的单一特征波段反演模型预测LAI精度R2为0.44~0.58;RMSE为0.16~0.18,其中636 nm建立的模型(LAI=21.86exp(-29.47R₆₃₆))相比其他反演模型预测精度较高（R2=0.58,RMSE=0.16）;6种植被指数与LAI高度相关,相关性系数R ²为0.85~0.86,以此建立的反演模型相比单一特征波段反演模型精度有所提高,R2为0.66~0.72,RMSE为0.12~0.14;其中mNDVI构建的LAI估算模型（LAI=exp(2.76~1.77/mNDVI))精度最高（R2=0.72,RMSE=0.13）。无人机高光谱遥感是快速、无损监测农作物生长信息的有效手段,为指导精细化尺度作物管理提供依据。     

新疆棉花LAI和叶绿素密度的高光谱估算研究

利用非成像高光谱仪,对棉花(2品种4水平种植密度)冠层5个关键生育时期进行光谱测定,分析棉花反射光谱及微分光谱生育期的变化规律,并对棉花冠层叶面积指数(LAI)、叶绿素密度(CH.D)与光谱数据进行回归分析,结果表明,用归一化差值植被指数(NDVI)与LAI建立的对数模型能够较好地估测棉花冠层的LAI(r=0.9123**,n=20);近红外729 nm波段处一阶微分光谱数值与CH.D高度相关(r=0.9372**,n=20),用此波段建立的CH.D估算模型,精度达84.3%,标准差为0.234g.m-2,RMSE=0.1569。研究表明,可以用高光谱数据对新疆棉花冠层LAI和CH.D进行遥感估算。     

大豆叶面积的高光谱模型

以ASD FieldSpec-Vnir光谱仪实测不同生长季大豆的冠层反射率,同期采集对应大豆LAI,然后逐波段分析冠层光谱反射率、导数光谱与大豆LAI的相关关系;并采用单变量线性回归逐波段分析了冠层光谱反射率、导数光谱与大豆LAI确定性系数随波长的变化趋势,建立了以近红外与可见光波段冠层光谱反射率的比值植被指数RVI与大豆LAI的高光谱遥感估算模型。结果表明,冠层光谱反射率在350￣680nm、760￣1050nm波谱区与大豆LAI相关性较大,而在红边区680￣760nm的相关性变化较大;导数光谱在红边区与大豆LAI相关程度高。通RVI方式建立的遥感估算模型能较为准确估算大豆LAI,通过对红外与蓝波段建立的RVI指数与大豆LAI的回归模型,表明其预测大豆LAI的能力较好,有进一步研究的必要;通过对比发现,神经网络模型可以大大提升高光谱反演大豆LAI的水平,模型的确定系数R2为0.9661,而总均方根误差RMSE仅为0.446m2.m-2。     

水稻冠层光谱特征及其与LAI的关系研究

氮素营养是影响作物生长与产量的最主要限制因子之一。准确及时地监测或诊断出作物氮素营养状况,对提高氮素利用效率和作物管理水平、减少过度施氮造成的环境污染具有重要意义。本研究在不同施氮水平处理的水稻试验小区,对水稻整个生长期内冠层反射光谱进行了较系统、密集的测定,同时测定了几个重要生育期水稻的叶面积指数。研究结果表明:随着施氮量的增加,水稻冠层光谱在各生育期间呈现出一定的规律性,在近红外部分(710～1 220 nm),冠层光谱反射率随着施氮水平的提高而升高,而在可见光部分(460～680 nm),水稻冠层的光谱反射率反而逐渐降低。经冠层光谱差异显著性检验发现:水稻灌浆期以前,对施氮水平最为敏感的波段是绿光(560～610 nm)和近红外(710～760 nm)部分;转换为归一化植被指数(NDVI)以后,差异最显著的是(R760-R560)/(R760+R560)。不同氮肥处理的水稻LAI随时间变化曲线大致都呈抛物线型,中低水平施氮肥水稻LAI随时间的变化曲线比较平缓,而高水平施氮肥LAI曲线则变化比较剧烈。冠层光谱反射与叶面积的相关分析结果表明:在水稻抽穗前,叶面积与冠层光谱反射率相关性较差;而抽穗后,叶面积与冠层光谱有较高的相关性。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

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。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。