苏、锡、常建成区遥感方法提取及城市扩展分析

将苏州、无锡、常州三市作为研究区域,详细介绍了借助遥感技术快速获取城市建成区的新方法和技术路线.将TM3、TM2两个波段移植于归一化建筑指数(NDBI)法,并同NDBI相结合提取城市建设用地,再通过制定的适于遥感划分建成区的界定方法.筛选出符合要求的建设用地得到三座城市的建成区范围.利用简单的统计方法和叠加分析方法,对...     

压力传感器的自动标定技术

针对压力测量设备生产和维护过程中,对关键部件压力传感器标定处于手工操作状态、效率低、操作人员不易掌控、标定结果处置复杂的现状,开发了针对压力传感器的自动标定技术。该技术将计算机控制、智能化、曲线拟合和误差分析引入到压力传感器的标定过程中,大幅度提高了标定的效率和可靠性。经此技术标定过的压力探头,在使用中具有互换性,减轻了数据后处理工作的难度。     

Vegetation greenness modeling in response to climate change for Northeast Thailand

In Northeast Thailand, the climate change has resulted in erratic rainfall and tem- perature patterns. The region has experienced both periods of drought and seasonal floods with the increasing severity. This study investigated the seasonal variation of vegetation greenness based on the Normalized Difference Vegetation Index （NDVI） in major land cover types in the region. An assessment of the relationship between climate patterns and vegeta- tion conditions observed from NDVI was made. NDVI data were collected from year 2001 to 2009 using multi-temporal Terra MODIS Vegetation Indices Product （MOD13Q1）. NDVI pro- files were developed to measure vegetation dynamics and variation according to land cover types. Meteorological information, i.e. rainfall and temperature, for a 30 year time span from 1980 to 2009 was analyzed for their patterns. Furthermore, the data taken from the period of 2001-2009, were digitally encoded into GIS database and the spatial patterns of monthly rainfall and temperature maps were generated based on kriging technique. The results showed a decreasing trend in NDVI values for both deciduous and evergreen forests. The highest productivity and biomass were observed in dry evergreen forests and the lowest in paddy fields. Temperature was found to be increasing slightly from 1980 to 2009 while no significant trends in rainfall amounts were observed. In dry evergreen forest, NDVI was not correlated with rainfall but was significant negatively correlated with temperature. These re- sults indicated that the overall productivity in dry evergreen forest was affected by increasing temperatures. A vegetation greenness model was developed from correlations between NDVI and meteorological data using linear regression. The model could be used to observe the change in vegetation greenness and dynamics affected by temperature and rainfall.     

基于MODIS数据的浒苔信息提取方法研究

浒苔是一种大型绿藻,大量浒苔爆发会严重影响景观,干扰旅游观光和水上运动的进行。本文利用NASA提供的MODIS02的250m分辨率影像,分别采用了比值法、归一化植被指数法和监督分类中的最小距离分类,提取了浒苔的信息,实验结果表明,三者都可以提取浒苔信息,但是比值法提取的结果最好,最小距离分类很难与薄云区分,必须加入人工目视解译,归一化植被指数可以区分出薄云,但是遗漏较多。     

高分三号SAR影像双阈值变化检测

双阈值合成孔径雷达SAR(Synthetic Aperture Radar)变化检测算法具有在发现变化区域的同时还能确定地表发生后向散射变化类型的优点。针对广义高斯双阈值最小误差法D-GKIT(Dual Generalized Kittler and Illingworth Thresholding)在进行阈值选取时直方图中不同类别像素灰度级重叠严重时,分割结果容易在尖峰单侧选取出双阈值而导致无法正确分割差异图的问题,本文提出一种结合归一化最大类间方差和广义高斯最小误差法GKIT(Generalized Kittler and Illingworth Thresholding)的双阈值SAR变化检测方法。首先,提出以归一化最大类间方差值作为灰度级重叠程度的判别参数,确定阈值的选取顺序及两个候选区间;然后,利用GKIT在候选区间内进行分割,获取单侧阈值及非变化类拟合函数;最后,提出利用非变化类拟合函数更新后的直方图作为另一侧阈值选取基础进行分割,得到对应分割阈值。以宁波地区高分三号(GF-3)SAR卫星影像作为试验研究数据,结果表明:本文方法能较好地解决灰度级重叠时D-GKIT无法进行正确分割的问题,具有良好的变化检测效果和更强的鲁棒性且达到了利用研究区数据验证利用GF-3号SAR卫星影像进行变化检测研究可行性的目的。     

基于多参量归一化的花岗岩巷道岩爆预测试验研究

通过室内模拟花岗岩巷道岩爆试验,基于线性函数转换的归一化算法,将试验中获得的声发射场和红外温度场等多参量进行归一化处理,在分析其原始曲线特征的基础上,分析各参量在同一尺度下的演化特征,综合研究花岗岩巷道岩爆前兆。研究结果表明:声发射事件率、声发射能率、最高和最低红外辐射温度均适合作为岩爆灾害预测的主要参数。岩爆发生过程中各参量经过归一化处理,在统一尺度下能够快速、有效地识别岩爆发生的前兆。声发射能量加速释放是岩爆发生的早期预警信息;声发射平静期可作为岩爆灾害预警与采取控制措施的关键时期;最低辐射温度突降和最高辐射温度突增表明岩爆随时都有可能发生,这是岩爆发生的征兆。试验结果为岩爆灾害预测研究提供了新的方法和依据。     

Vegetation change of ecotone in west of Northeast China plain using time-series remote sensing data

Multi-temporal series of satellite SPOT-VEGETATION normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) data from 1998 to 2007 were used for analyzing vegetation change of the ecotone in the west of the Northeast China Plain. The yearly and monthly maximal values,anomalies and change rates of NDVI and NDWI were calculated to reveal the interannual and seasonal changes in vegetation cover and vegetation water content. Linear regression method was adopted to characterize the trends in vegetation change. The yearly maximal NDVI decreased from 0.41 in 1998 to 0.37 in 2007,implying the decreasing trend of vegetation activity. There was a significant decrease of maximal NDVI in spring and summer over the study period,while an increase trend was observed in autumn. The vegetation-improved regions and vegetation-degraded regions occupied 17.03% and 20.30% of the study area,respectively. The maximal NDWI over growing season dropped by 0.027 in 1998–2007,and about 15.15% of the study area showed a decreasing trend of water content. Vegetation water stress in autumn was better than that in spring. Vegetation cover and water content variations were sensitive to annual precipitation,autumn precipitation and summer temperature. The vegetation degradation trend in this ecotone might be induced by the warm-drying climate especially continuous spring and summer drought in the recent ten years.     

坐标转换模型在盾构姿态计算中的应用

在附有条件的间接平差模型的基础上,提出用归一化大角度坐标转换模型计算盾构机姿态,并从其原理、方法以及精度上进行了分析。应用结果表明:利用坐标转换法计算盾构机姿态,与常规解方程法相比较更能有效利用参考点的所有信息,计算过程简明,且便于程序实现。     

STUDY ON THE INTERACTION BETWEEN NDVI PROFILE AND THE GROWING STATUS OF CROPS

Daily and ten-day Normalized Difference Vegetation Index(NDVI) of crops were retrieved from meteorological statellite NOAA AVHRR images ,The temporal variations of the NDVI were analyzed during the whole growing season,and thus the principle of the interaction between NDIV profile and the growing status of crops was discussed,As a case in point,the relationship between integral NDVI and winter wheat yield of Henan Province in 1999 had been analyzed.By putting integral NDVI values of 60 sample counties into the winter wheat yield-integral NDVI coordination,scattering map was plotted. It demonstrated that integral NDVI had a close relation with winter wheat yield.These relation could be described with linear,cubic polynomial ,and exponential regression,and the cubic polynomial regression was the best way,In general ,NDVI reflects growing status of green vegetation ,so crop monitoring and crop yield estimation could be realized by using remote sensing technique on the basis of time serial NDVI data together with agriculture calendars.     

2022年青海门源M_(S)6.9地震前地电阻率变化分析北大核心CSCD

分别运用原始曲线分析法和归一化速率方法分析门源地震震中300 km范围内3个地电阻率台站数据变化。从原始曲线来看,金银滩台EW道临震前2个月出现大幅突跳及保留年变形态的趋势下降(-3.3%);山丹台NS道趋势下降(-1.9%)、EW道趋势上升(3.1%);武威小西沟台NS道趋势下降(-3.3%)、EW道趋势上升(2.8%),震后EW道趋势转平。而3个地电阻率台站归一化速率曲线在门源地震前均出现超过阈值的现象,但各自归一化速率形态存在差异。整点值突跳变化和日均值、月均值曲线加速变化、转折变化,尤其是上升至高值阶段出现的转折变化均可作为异常形态进行分析,以上变化不明显时需结合归一化速率方法提取异常。