C3、C4作物的光保护机制差异的光谱探测研究

本文设计了大豆(C3作物)和玉米(C4作物)日变化光谱探测试验,提取了太阳光照条件下叶绿素荧光信号和光化学指数PRI。结果表明,首先大豆和玉米叶绿素荧光强度的日变化特征有较大差异,上午大豆的叶绿素荧光比例呈现快速增加的趋势,而玉米的叶绿素荧光未出现增加趋势;其次,下午高温胁迫条件下C3、C4叶绿素荧光光谱比值的变化差异显著,大豆在760nm和688nm波段的叶绿素荧光比值快速增加,而玉米未出现显著变化;最后,研究证实了C3作物中午受到强光抑制出现光合作用"午休"现象,即午后光合恢复后其光合效率快速增加,表现为C3作物的热耗散降低、PRI快速增加,而C4作物无"午休"现象,午后PRI增加较小。本文研究表明,强光和高温环境胁迫下C3、C4作物的叶绿素荧光和热耗散变化特征有较大差异,利用胁迫条件下的多时相、高光谱遥感数据,提取C3、C4作物的叶绿素荧光和PRI,有可能实现C3、C4作物的遥感分类目标。     

The Campo Felice late Pleistocene Glaciation (Apennines,central Italy)

Study of the glacial deposits and lacustrine sediments of Campo Felice (Apennines, central Italy) has enabled the glacial phases of the last 40 ka to be dated more precisely, and has demonstrated that the maximum glacial advance did not occur in correspondence with the last global glacial maximum and with the coldest and most arid phase suggested by the pollen, but in a period dated between about 33 and 27 ka, characterized by a less extreme climate. Furthermore, a glacial expansion took place also in the period prior to 35 ka. Correlation with the Alpine glacial variations has shown that the Apennine last glacial maximum occurred before that of the southern slope of the Alps. Copyright © 2012 John Wiley & Sons, Ltd.     

A PREDICTION SCHEME FOR THE PRECIPITATION OF SPR BASED ON THE DATA MINING ALGORITHM AND CIRCULATION ANALYSIS

Based on the 74 circulation indexes provided by National Climate Center of China (hereinafter referred to as NCC) and the 24 indexes compiled by NOAA, the study used the C4.5 algorithm in data mining to establish a decision tree prediction model to predict whether the Spring Persistent Rains (hereinafter referred to as SPR) of 55 years (from 1961 to 2015) is more than the normal, and obtained 5 rules to determine whether the SPR is more than the normal. The accuracy rate of the test set, namely “whether the SPR is more than the normal”, is 98.18%. After evaluating the model by conducting ten 10-fold cross validations to take the average value, the test accuracy rate gained is 84%. There are differences between the three types of years with a SPR more than the normal when it comes to intensity and distribution. In spring, they have respective anomalous 850hPa monthly mean wind fields and water-vapor flux distribution, and 700hPa forms the zone where the vertical speed is anomalously negative. As indicated by the results, the SPR prediction model based on the C4.5 algorithm has a high prediction accuracy rate, the model is reasonably and effectively constructed, and the decision rules take comprehensive factors into consideration. The anomalous rainfall and circulation distribution characteristics obtained based on the decision classification results provide new ideas and methods for the climatic prediction of SPR.     

资源一号02C卫星数据在北京岩溶水资源勘查评价工程中的应用

以资源一号02C(ZY1-02C)卫星数据为数据源,以GIS为数据处理平台,以遥感地质理论和水文地质理论为指导,将遥感技术应用于北京岩溶水资源勘查评价工程中。通过水文地质遥感解译和综合分析,优选了一处新的供水水源地,建立了适用于北方岩溶区的含水岩组和泉点的遥感解译标志,提出了基于GIS的水文地质分析方法,扩展了国产资源卫星数据的应用领域。     

GPS现代化后L2载波的数据质量分析

从L2C码的信号结构、多路径效应和信噪比3个方面对实际采集到的观测数据进行分析,结果表明,新的L2C码采用了新的设计结构,其多路径效应与C/A码的多路径效应较为一致,且L2载波的信噪比得到明显提高。然后利用L1载波和L2载波分别求解双差模糊度,实验结果说明,加载了L2C码的L2载波和L1载波计算双差模糊度的效果一致,较原未加载L2C码的载波在模糊度解算效率上有显著的提高。     

一种断面测量数据的自动处理方法

断面测量在道路施工和一些需要利用断面数据计算土方的工程中有着广泛的应用。为提高断面测量数据处理的效率,文章采用Visual C++编程语言,编制了可以根据特定需求处理断面测量数据的程序。实践证明,该程序较好地提高了断面测量数据处理的效率和精度,可以为断面测量数据程序化处理提供参考。     

基于虚拟相关对技术的C/A码相关峰形变监测算法

"主从相关器"结构的接收机常被用来监测C/A码相关函数相关峰的形变,但受制于相关器数量的影响,在GPS卫星低仰角时,监测器并不能及早地发现信号形变,针对这一问题,该文在"主从相关器"结构的接收机基础上,采用了虚拟相关对技术,通过已知的3组相关对(一组"主相关对",两组"从相关对")和Prompt相关器输出,以码片间距为自变量,采用最小二乘的方法,拟合相关器相关值输出三次曲线。拟合曲线上的点作为构建的虚拟相关对输出,它们与已知相关器的输出一起进入之后的相关函数相关峰性形变监测部分处理。采用此种方法,不仅不会遗漏传统算法用到的待测量,而且能扩大待测量的样本空间。同时,该方法不会因为加入新的待测量产生误测。通过仿真发现,在使用3组相关对和Prompt相关器,且GPS卫星仰角较低时,该算法比传统算法更早监测到C/A码形变。     

Perihelion motion of small irregular dust particles due to radiation forces

Perihelion motion, i.e. a secular change of longitude of perihelion, of interplanetary dust particles is investigated under the action of solar gravity and solar electromagnetic radiation. As for spherical particle [Kla?ka, J., 2004. Electromagnetic radiation and motion of a particle. Cel. Mech. Dynam. Astron. 89, 1-61]: (i) perihelion motion is of the order ( is heliocentric velocity of the meteoroid and c is the speed of light in vacuum), if a component of electromagnetic radiation acceleration is considered as a part of central acceleration; (ii) perihelion motion is of the first order in if the total electromagnetic radiation force is considered as a disturbing force. The new facts presented in this paper concern irregular dust particles. Detailed numerical calculations were performed for the grains ejected at aphelion of comet Encke. Perihelion motion for irregular interplanetary dust particles exists already in the first order in for both cases of central accelerations. Moreover, perihelion motion of irregular particles exhibits both positive and negative directions during the particle orbital motion. Irregularity of the grains causes not only perihelion motion, but also dispersion of the dust in various directions, also normal to the orbital plane of the parent body.     

《测绘法》适应性浅析

分析了新时期测绘发展面临的新形势,对《中华人民共和国测绘法》规定的有关概念内涵、管理体制、运行机制、准入制度等的适应性进行了探讨,对进一步修订《中华人民共和国测绘法》提出了建议。     

全球定位系统的新进展(讲座三)——GPS中的民用测距码

介绍了C/A码、L2C码以及L5码的生成方式、测距精度及特性,并对GPS系统中测距码的扩充作了简要介绍。