旋翼无人机测算风速风向技术研究

目前大部分民用无人机没有准确测量风速、风向和预警风场的功能,然而森林火灾扑救等多种场景需要无人机可以提供准确的风速。本文提出了一种基于旋翼无人机坐标数据测算风速风向的技术,通过无人机主机RTK坐标信息及方位角、倾角数据精准获取螺旋桨点相对坐标信息,选择不同负载条件下无人机以1~16 m/s的不同速度分别飞行30 s以上,根据螺旋桨坐标信息变化数值,结合风洞测试数据及风场动力学原理,研究风速与旋翼无人机倾角关系,并通过风洞试验检验该方法精度;并可根据无人机RTK推算出的螺旋桨坐标变化信息判断风向。结果表明,无人机风速与旋翼无人机倾角呈正相关关系;无人机负载加重时,对应受风速干扰的倾角会相对减小;无人机飞行受阵风干扰出现噪点的概率,高海拔区域大于低海拔区域;并建立六旋翼无人机飞行倾角的风速估算模型y=－1.043 5+1.150 1x,该模型测算风速的中误差值为0.966,绝对值小于1,满足应急指挥现场对无人机测量风速精度要求。该方法得到风速测算精度高,可以为旋翼无人机实时获取风速风向提供一种可行方法,具有一定的实用价值。     

Multi—quadric Equations Interpolation and Its Applications to the Establishment of Crustal Movement Speed Field

In this paper,multiquadric equations interpolation is used to establish a widely covered and valuable speed field model,with which the crustal movement image is obtained.     

Estimation of soil moisture using deep learning based on satellite data: a case study of South Korea

The Korea Meteorological Administration uses soil moisture (SM) observed by the Advanced Microwave Scanning Radiometer-2 (AMSR2) to monitor drought. However, it may not be appropriate for monitoring drought in South Korea due to significant underestimation of SM. In this study, we used a deep learning method that performs better than traditional statistical and physical models for reliable estimation of SM based on remotely sensed satellite data. For estimating SM, we carefully selected input variables that exhibit a feedback loop with SM. To build an effective deep learning model, we examined the influences of sampling criteria and input parameters as well as the accuracy of several deep neural networks. The selected model was cross-validated to determine its stability. The estimated SM using deep learning had a high correlation coefficient (R) of 0.89 and a low root mean square error (RMSE; 3.825%) and bias (?0.039%) compared to in-situ measurements. A time series analysis using dynamic time warping was conducted which showed that the estimated SM was almost similar to the in-situ SM. In order to investigate the improvement in SM estimation using our method, it was compared with the Global Land Data Assimilation System and AMSR2. Significant improvements in R and a reduction in error values by more than half were achieved using our method. The estimated SM has finer spatial resolution at 4 km, and it can be rapidly produced, which will be useful for drought monitoring over the Korean Peninsula in near-real-time.     

Spatial estimation of wind speed: a new integrative model using inverse distance weighting and power law

Spatial interpolation (SI) is currently one of the most common ways to estimate wind speed (Ws). However, classic SI models either ignore the complex geography [e.g. inverse distance weighting (IDW)], or demand high computational resources (e.g. cokriging). This study aimed to develop a simple yet effective SI model for estimating Ws in Eastern Thrace of Turkey. This new method, named MIDW_(Ws), is a modified IDW through the integration of IDW with wind profile model, power law (PL), representing the influence of land cover and topography on Ws. Terrain features and elevation data of PL were obtained using normalized difference vegetation index (NDVI) and digital elevation model (DEM), respectively. Results showed superior and comparable performance of MIDW_(Ws) to standard IDW and ordinary kriging (OK) across all months of year. Compared to ordinary cokriging (OCK) using DEM as covariate, MIDW_(Ws) generated better results in the arid–semiarid seasons (around summer). Local complex atmospheric conditions during rainy seasons (around winter) may have affected the performance of incorporating PL with MIDW_(Ws). Generally, the proposed MIDW_(Ws) is simpler and easier to implement compared to OCK. For landscape-scale projects, its high computational efficiency and relatively robust performance show potential to deal with large volumes of datasets.     

分形模拟在DEM内插中的应用

为提高DEM的空间分辨率,避免线性插值方法的平滑和低通滤波作用,本文依据地形的分数布朗运动(FBM)特性,提取地形的分形参数,利用分形模拟方法进行插值,并将不同地形的试验结果与线性插值方法进行比较和分析.结果表明该方法能较好保持地形的随机性、不规则性和丰富的细节信息,同时也具有一定的插值精度.     

基于广义延拓法的精密卫星钟差插值

在GPS数据处理中,需要高采样率的精密卫星钟差,而IGS仅提供5 min间隔的卫星钟差,在实际应用中,必须内插出更小的采样间隔的数据。本文尝试将广义延拓法用于GPS精密卫星钟差插值,将5 min和15 min间隔的数据插值到30 s间隔,探讨插值精度与三个参数的关系,并将结果和GFZ提供的精密卫星钟差及其他插值方法得到的结果进行比较。结果表明,广义延拓插值法具有较高的精度,完全适用于GPS精密卫星钟差的插值。     

多维线性内插在变形监测数据分析中的应用

针对变形监测中由于形变体的变形是多因素同时作用,且各个变形因子对变形体的作用非线性,导致难以准确分析变形因子与形变量的函数关系的问题,该文提出一种多维空间线性内插的数据分析方法,实验结果表明:通过该方法不仅可以较准确分析出每个变形因子与形变量的关系,而且可以探测出形变量的跳变,为其他经验模型分析方法提供参考。     

基于特征点修正的SRTM数据在风能资源微观评估中的应用

在风能资源微观评估中,高精度地形数据通常较难获取,寻找一种可替代数据尤为重要。本文以全球免费共享的SRTM数据(90m水平分辨率)为地形数据源,利用风图谱分析及应用程序(WAsP)作为风资源评估工具,对广东遮浪岛区域进行了定点风能资源评估。通过将评估结果与1:5千地形数据条件下的结果进行对比,分析了SRTM数据用于风能资源微观评估的精度。接着,本文提出了地形数据的特征点修正方法,利用该方法处理后的SRTM数据,平均风速在两种不同地形数据源下的相对误差由10%降为5%,使得修正后的SRTM数据可适用于风能资源微观评估。     

FY-3B 微波成像仪海表面温度和风速统计反演算法

基于同步的TAO (Tropical Atmosphere Ocean project) 浮标实测数据和FY-3B 微波成像仪(MWRI) 亮温数据,建立了FY-3B MWRI 海表面温度SST(Sea Surface Temperature) 和海面风速SSW(Sea Surface Wind) 统计反演算法,并利用实测数据进行了检验.根据检验结果,FY-3B MWRI 全通道亮温的SST 反演模型均方根误差为0.81 ℃,相关系数为0.77; SSW 反演模型均方根误差为0.91 m/s ,相关系数为0.78 .     

网络RTK内插和外推比较分析

GPS流动站用户在使用网络RTK时,会出现在基准站网区域范围内和区域范围外两种情况,文中从数学模型和实例数据计算两方面,详细分析和比较网络RTK中内插和外推综合误差时的精度差异。     

三次样条在卫星轨道插值中的应用研究

针对在卫星轨道插值中三次样条插值法的端点约束条件不易获得的问题,提出两种获得端点一阶导数的计算方法:差分法代替导数法;利用位置、速度和加速度之间的导数关系,求解坐标和速度的一阶导数。通过算例仿真表明,两种方法的坐标插值误差达毫米级以上,速度插值误差达厘米级以上,它们的插值精度均不受分段弧长影响,且比7阶Lagrange插值精度要高,但它们的运算时间比7阶拉格朗日插值法略大。其中,方法一优于方法二,因前者的速度插值误差比后者小,且后者的插值结果存在周期性抖动现象,其抖动周期与抽样频率有关。文中方法具有插值精度高,插值精度不受分段弧长影响,运算量不大的优点,是一种实用的卫星轨道和速度插值方法。     

Robust estimation and optimal selection of polynomial parameters for the interpolation of GPS geoid heights

The polynomial interpolation of least squares and interpolation moving least squares based on control stations with known GPS (global positioning system) ellipsoidal heights and levelling orthometric heights are the most often used methods for the interpolation of the geoid heights. But in their applications there occur two problems: one lies in selecting the suitable polynomial parameters; the other in reducing the influences of some possibly abnormal data points. To solve both of the problems, without emphasizing a sound theoretical basis, a heuristic solution with the help of robust estimation technique and optimization criteria for the regression equation is presented. Through two actual numerical examples it is shown that the new solution concept is efficient and can be realized easily on computers. Received: 23 May 1996 / Accepted: 27 March 1997     

遥感影像大气校正通用查找表的设计与插值算法

大气参数查找是遥感图像大气校正中一个重要的步骤。本文针对当前多数大气参数查找表普适性不强、查找表数据存储空间巨大、具体实施步骤不详细的问题,建立了一个通用化的多维大气参数查找表,其光谱分辨率为1 nm,并适用于多种遥感传感器。本文采用二进制文件方式存储查找表,并研究采用多维拉格朗日和多维反距离加权插值方法对输入参数进行插值。结果表明以二进制文件方式存储查找表,不但可以最大化地减少磁盘存储空间,还可以实现查找表数据快速随机读取;相对于多维反距离加权插值方法,多维拉格朗日插值方法的速度更快,精度更高,与MODTRAN4.0模型计算结果(真值)相比,它的误差仅为±1.0%左右。     

朝鲜人口统计数据空间化模拟及影响因子分析

朝鲜人口统计数据空间化是解决朝鲜统计数据与自然要素数据融合分析的重要途径。基于朝鲜市郡级人口普查数据,将GIS空间分析技术与统计学方法相结合,分析了朝鲜人口密度与空间因子的关系,采用多元回归的方法建立了朝鲜人口密度空间化模型,在GIS平台中实现了朝鲜人口密度的空间格网化模拟,并利用地理探测器对影响朝鲜人口密度空间分布因素的决定力进行了有效探测。结果表明,多元回归模型拟合精度达到0.769,生成的栅格人口密度数据与朝鲜三级行政区人口统计数据保持一致。同时,影响该地区人口密度的因子依次为道路网密度、居民点密度、居民地指数、海拔、坡度和耕地指数。     

韩国和马来西亚建立本国三维地心大地坐标系统的进展

介绍了韩国大地坐标系统的沿革 ,阐述了近年来韩国建立本国三维地心坐标系的工作和进展。为了对比韩国 ,简约介绍了马来西亚等国在这方面的新进展     

最大熵模型结合遗传算法解算DEM插值权系数

针对传统格网DEM插值数学模型在解算权系数时存在负权现象的问题,提出了解算DEM插值权系数的最大熵模型算法。首先,以熵函数作为目标函数,以参考点数据的0、1、2阶统计矩作为约束条件,并增设非负约束条件,通过最大化熵值来求解格网DEM插值的非负权系数;其次,利用罚函数法,将有约束问题转化为无约束问题,并结合遗传算法的全局最优化特性进行优化解算。在MATLAB平台编程验证算法的正确性、准确性,并与杨赤中法、二次规划法进行了比较。对比显示:最大熵法解得权系数大小比例与点位关系相适应,且其估值精度优于杨赤中法、二次规划法。     

遥感和GIS技术在全球海面风速分析中的应用

将遥感技术和地理信息系统（GIS）技术相结合，建立了一个基于TOPEX卫星的全球海面风速分析的海洋地理信息系统（MGIS）。阐述了全球海面风速分析模型的建立方法，定义了描述风场特征的相关参数，介绍了全球海面风速海洋地理信息系统的结构、功能和工作流程，另外，对系统的3个应用实例进行了地学分析。     

中国地壳运动整体速度场模型的建立方法研究

利用所能得到的468点的高精度GPS速度场,采用计算欧拉矢量法和多面函数拟合法分别在细分块体和不细分块体的情况下建立了中国地壳运动整体速度场模型,并对其结果进行了分析。结果表明,在对块体介质刚弹性的认定不明确时,多面函数拟合法比计算欧拉矢量法更适合中国平面地壳运动速度场模型的建立。     

Spatio-temporal variation in childhood growth in Nigeria: a comparison of aggregation and interpolation

ABSTRACT

The mean height-for-age Z-score (HAZ) of children under five is an important indicator of the health status of a population. HAZ values are frequently aggregated and reported at the national level, potentially obscuring important within-country variation. We evaluated aggregation and interpolation methods to provide sub-national estimates over space and time, using survey data from Nigeria in 1990, 2003, 2008, and 2013. We aggregated HAZ values by region and by state, and interpolated the values spatially and spatio-temporally using thin plate splines. The results were evaluated with cross-validation using the root mean squared error (RMSE) as a measure of goodness of fit. Mean HAZ values increased from 1990 to 2013, but values rose more sharply in southern Nigeria than in the North. All methods performed better than assuming a constant national average. The state-level aggregation, and the spatial and spatio-temporal interpolations had similar RMSE values, but the interpolation methods showed more detailed spatial variation. Spatio-temporal interpolation produced good results in all conditions, including in years with sparse sampling and when extrapolating to years for which there were no observations.     

Spatiotemporal patterns of outdoor artificial nighttime lights exposure in the Republic of Korea between 1995 and 2010

Outdoor light at night (LAN) would be a public concern potentially associated with adverse health outcomes mainly in developed countries, but it might also be an environmental health issue in developing countries. However, there have been few studies reporting the spatial and temporal aspects of LAN level changes incorporated with population exposure in such nations. Therefore, we analyzed the spatiotemporal patterns of outdoor LAN exposure changes across the Republic of Korea (ROK), a developing country in Asia, between 1995 and 2010. In addition, we incorporated the population and its demographic characteristics of light exposure in this research. We utilized Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) observations as a spatial proxy of LAN and the ROK census data. This research observed 57.6% (≈57,800 km²) of land areas in the country to experience increases in outdoor artificial illumination at nights. The highest levels of LAN were found to affect about 58% of the total ROK population with major impacts on young and middle-aged people in recent years. Taking this research into account, it would require taking appropriate measures in controlling and abating outdoor artificial lights at night for both developing and developed countries. We anticipate that those efforts could prevent adverse health outcomes, for example, female breast cancer, potentially associated with LAN exposure.