玉米冠层最佳水分指数优选

针对基于植被指数反演不同生长期、不同冠层结构特征下玉米冠层含水量的序列性研究较少,冠层含水量反演较低等问题,优选不同生长期玉米冠层含水量反演最佳植被指数,完成玉米冠层含水量高精度提取。初步选择4种可靠性强的水分指数:归一化植被指数、归一化水体指数1、归一化水体指数2、水协迫指数,分别基于PROSAIL辐射传输模型、三期实测冠层含水量及同步Landsat-8OLI数据,模拟分析4种植被指数与冠层含水量的关系,优选不同生长期玉米最佳水分指数,实现玉米冠层含水量快速精确反演。实例验证结果表明,水分指数归一化水体指数1可作为植被冠层含水量反演的最佳指数且反演精度随着植被含水量的增加而降低,在玉米生长初期,中误差为0.13kg/m~2,在生长中后期,中误差达到0.582kg/m~2,满足生长初期玉米冠层含水量快速反演需求。研究结果可为植被冠层含水量反演中水分指数选择提供参考,也可为稀疏植被覆盖区土壤水分反演研究提供借鉴。     

虚拟玉米植株三维动态建模

研究虚拟植物生长发育过程,为克服传统建模中玉米器官生长形态定义不够精确和生物学意义缺失,采用实际田野实测,引入动力学,给玉米植株生长模型赋予生物学意义,提出玉米植株生长造型更为精确的描述,根据图形学技术构造玉米植株生长过程的三维几何形态,对不同生长期的形态变化进行动态仿真,实验结果表明与实际拍摄的玉米植株生长发育过程一致.模型可控性强、真实感强,能较好地仿真玉米植株的生长过程.     

基于生长动力学的芦苇属植株虚拟生长模型

针对植株形态建模过程中由于缺乏生理生态特性而导致模型无法真实再现植株生长发育规律的问题,提出了一种基于生长动力学的植株形态变化模型构建方法。以芦苇属植株为例,首先研究了植株生长动力学特性,并以有效积温、生长速率变化等为驱动力构造了植株形态建成模型;其次,应用开放式L系统(Open-L)方法描述了植株冠层拓扑演变过程;最后,通过耦合植株拓扑与器官形体的几何模型及显示模型,给出了植株虚拟生长模型构建算法。实验结果表明,该方法实现了植株形态的可视化,并反映了植物生长机理,有利于动态掌握和预测植物生长发育状况。     

基于植被指数的叶绿素密度遥感反演建模与适用性研究

利用遥感数据反演叶绿素密度是对作物长势进行评估的有效手段.本文利用实测冬小麦和夏玉米两种作物、不同生育期的冠层光谱和叶片叶绿素含量数据,收集了14种光谱指数,分析各种光谱指数的叶绿素密度遥感模型的精度.优选了其中的8种植被光谱指数,建立了植被指数与叶绿素密度之间的回归模型,并利用不同生育期小麦数据和玉米数据对各模型进行验证,分析评价它们对不同生育期、不同作物类型的适用性.研究发现:利用SRI、RVI I、R-M和MTCI 4种植被指数所建模型对冬小麦不同生育期数据适用性较好,各生育期冠层叶绿素密度反演相对误差优于27％.其中,MTCI模型对不同作物类型的适用性最好,冠层叶绿素密度反演相对误差优于35％.     

不同生育期倒伏胁迫下玉米叶面积指数高光谱响应解析

为研究倒伏胁迫下不同生育期LAI高光谱响应模型,提高LAI高光谱响应模型精度,获取不同生育期倒伏玉米LAI与冠层光谱反射率,采用6种传统变换方式对高光谱反射率进行处理,构建不同生育期倒伏玉米LAI分期与统一响应模型。研究结果表明：LAI能够直接反映玉米受倒伏胁迫程度及自身恢复能力;传统光谱变换有利于提高光谱同LAI的敏感性及模型响应精度;不同生育期倒伏玉米LAI分期响应模型优于统一响应模型。该结果可有效诊断倒伏胁迫下的玉米叶面积指数,为实现不同生育期倒伏玉米长势精确监测提供理论依据和技术支撑,对玉米倒伏胁迫灾情监测可提供必要的先验知识。     

不同生育期倒伏胁迫下玉米叶面积指数高光谱响应解析

为研究倒伏胁迫下不同生育期LAI高光谱响应模型,提高LAI高光谱响应模型精度,获取不同生育期倒伏玉米LAI与冠层光谱反射率,采用6种传统变换方式对高光谱反射率进行处理,构建不同生育期倒伏玉米LAI分期与统一响应模型。研究结果表明:LAI能够直接反映玉米受倒伏胁迫程度及自身恢复能力;传统光谱变换有利于提高光谱同LAI的敏感性及模型响应精度;不同生育期倒伏玉米LAI分期响应模型优于统一响应模型。该结果可有效诊断倒伏胁迫下的玉米叶面积指数,为实现不同生育期倒伏玉米长势精确监测提供理论依据和技术支撑,对玉米倒伏胁迫灾情监测可提供必要的先验知识。     

不同生育期倒伏胁迫下玉米叶面积指数高光谱响应解析

为研究倒伏胁迫下不同生育期LAI高光谱响应模型，提高LAI高光谱响应模型精度，获取不同生育期倒伏玉米LAI与冠层光谱反射率，采用6种传统变换方式对高光谱反射率进行处理，构建不同生育期倒伏玉米LAI分期与统一响应模型。研究结果表明：LAI能够直接反映玉米受倒伏胁迫程度及自身恢复能力；传统光谱变换有利于提高光谱同LAI的敏感性及模型响应精度；不同生育期倒伏玉米LAI分期响应模型优于统一响应模型。该结果可有效诊断倒伏胁迫下的玉米叶面积指数，为实现不同生育期倒伏玉米长势精确监测提供理论依据和技术支撑，对玉米倒伏胁迫灾情监测可提供必要的先验知识。     

利用辐射度模拟虚拟枇杷果园冠层光分布

利用计算机定量化模拟植物形态结构和冠层内的光分布是评估植物光合作用潜力与潜在产量的重要方法。以枇杷为例,采用参数化单树建模工具ParaTree构建单株三维枇杷冠层模型,基于反距离加权插值法IDW建立地形表面模型;根据枇杷果园的树木分布情况,把单株木模型“种植”于地形表面,形成虚拟枇杷果园场景。整个三维场景以三角形面元为基本图元表达,利用辐射度算法模拟虚拟枇杷果园冠层内的光传输与光分布,计算到达每片三角形面元的光辐射强度,可模拟不同种植密度下枇杷果园冠层对光的利用率,为枇杷的种植设计提供参考。     

基于SAILH模型的植被冠层NDVI二向性分析

NDVI是植被遥感中最为常用的一种植被指数,建立NDVI与其他冠层参数模型必须考虑其方向性问题.本文基于SAILH模型讨论了连续植被冠层NDVI的二向性特征,并分析了叶面积指数、叶倾角分布、热点参数以及太阳天顶角和相对方位角对NDVI的影响.研究表明冠层NDVI在主平面观测方向存在一个明显的负热点,前向散射方向的NDV...     

基于三维激光扫描技术的马尾松冠层孔隙度研究

三维激光扫描技术具有扫描快、对树木无损害、高度还原树木原形等优势，为三维样木重构、树木冠层结构研究及森林资源连年监测研究提供精确的数据。以马尾松为对象，利用三维激光扫描仪获取30株单木点云数据，运用体素化、平面投影和凸包算法等，计算单木冠层孔隙度。结合分层理论，通过与树木生长参数(冠幅、冠体积和冠高度)的相关性分析，构建全冠与不同分层方式提取的冠层孔隙度建立多元线性回归模型，以决定系数(R²)、均方根误差(RMSE)、相对分析误差(RPD)和总体精度(TA)确定冠层孔隙度提取的最佳体素边长和最佳分层方式。结果表明：冠层孔隙度提取的最佳的分层方式为冠层形态三分层(R²为0.74)；冠层形态三分层、冠层形态三分层五分层结合、冠层高度三等分层提取的冠层孔隙度与树木生长参数的影响最为稳定；根据冠层形态分层提取的孔隙度适用于冠层形态差异较大，而冠层形态较一致时，采用冠层高度三等分层是较为合适，精度较高。     

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.     

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.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate