Optimal locations for flow and velocity sensors along a river channel

ABSTRACT

A novel methodology for the optimal placement of sensors in watercourses is presented. The methodology aimed at finding the optimal locations for the placement of sensors to maximize the amount of information to monitor flow and velocity in watercourses. The methodology is based on the maximization of the Gram determinant of the sensor responses at each possible location or a combination of locations. Two illustrative examples are presented wherein locations for one- and two-sensor cases for the velocity and flow monitoring of the Venero Claro River Basin, Spain, are selected. The kinematic wave method was used to evaluate the sensor response at every possible location. The results confirm the suitability of this methodology for finding the optimal locations for sensors to monitor flow or velocity in watercourses.     

Crowdsourced approaches for stage measurements at ungauged locations using smartphones

ABSTRACT

The growing availability of smart devices with advanced sensors has increased the opportunities for citizen science applications for environmental monitoring. Accurate and widespread monitoring of river stage is vital for modeling water resources. Reliable data points are required for model calibration and validation in forecast studies. While current embedded monitoring systems provide accurate measurements, the cost to replicate these systems on a large domain is prohibitively expensive, limiting the quantity of data available. This project describes a new method to accurately measure river levels using smartphone sensors. Pictures of the same point on the river’s surface are taken to perform calculations based on the GPS location and spatial orientation of the smartphone. The proposed implementation is significantly more accessible than existing water measuring systems while offering similar accuracy. A case study is performed to evaluate the accuracy and sensitivity of the measurements to changes in distance.     

高层建筑动力反应实测中测点的优化布置方法的研究

本文对高层建筑动力反应实测中测点的优化布置方法进行了研究，研究了几种表示测点布置是否最优的适应度函数，并且应用最优化计算方法来寻找测点最优或接近优化的布置。本文还通过一个高层建筑动态响应测试的实例，说明了具体的应用方法。实际计算表明，用本文方法布置测点所测得的结构动态响应结果有相当高的精度。     

TDT-25型地温传感器的设计

介绍了专用于地震前兆观测的TDT—25型地温传感器的设计原理及其各个功能模块的工作原理。文章还给出了该地温传感器的测试结果和应用图例，证明该传感器完全满足地震前兆观测的需要。     

卫星观测到的全球闪电活动及其地域差异

闪电活动在时间和空间尺度上都有很大的可变性. 本文利用热带降水测量计划（TRMM）卫星上携带的闪电探测系统获取的闪电定位资料首次对一些典型地区的闪电活动进行了对比分析. 研究发现不同地区的闪电活动无论在闪电频数或放电强度方面都有很大的差别，海洋上的闪电活动频数与陆地上的闪电活动频数可相差几十倍；不同地区闪电活动的多少不仅取决于该地雷暴日数的多少，更重要的还取决于该地每次雷暴过程闪电频数的多少；不同地区的闪电放电强度有随闪电频数增加而减小的趋势. 进一步研究还表明，不同地区闪电光辐射能的不同可以用对流最大不稳定能量（ECAPE）来解释，闪电放电强度与ECAPE之间存在非常好的线性正相关；而闪电活动频数对ECAPE的响应则与闪电光辐射能不同，二者之间没有发现明显的相关.     

Impact of aerosols on total columnar ozone measurements—a case study using satellite and ground-based instruments

Long-term record of global distribution of ozone during 1979 to 2001, from Total Ozone Mapping Spectrometer (TOMS), over a tropical urban environment has been analyzed and compared with ground measurements. Increase in atmospheric UV-absorbing aerosol loading has been observed after 1991. TOMS columnar ozone during 1979 to 2001 suggested a clear Gaussian pattern of minimum concentration in winter months and maximum in summer months. TOMS ozone showed good correlation with the ground measured columnar ozone during winter months and negative correlation with Sunburning Ultraviolet (SUV) (280–370 nm), UVA and aerosol optical depth (AOD).     

利用NOAA-AVHRR观测数据反演云辐射特性的一种迭代方法

在可见光谱区 ,云的反射函数主要依赖于云的光学厚度 ;在近红外和中红外光谱区 ,云的反射函数主要依赖于云滴有效半径。根据上述原理 ,我们开发了一个利用NOAA AVHRR观测资料同时反演云的光学厚度和云滴有效半径的迭代方案。将该方案用于分析中国东海上空冬季层积云的辐射特性 ,取得了较为合理的结果。     

一种新型机载测温仪

一种由铂膜Pt100作为感温元件的新型机载气温测量仪在中国气象科学研究院研制成功。其选用的元器件是经过严格挑选过的，整机工作稳定，几乎无漂移，测量精度高，经国家气象计量检定站静态条件下标定，在－20－40℃范围内最大测量误差不超过0.1℃，Pt100的响应时间小于0.1s(厂家提供）。另外，该测温仪除测值可实时显示外，还配置了具有实时曲线显示、数据存储和统计等功能的应用软件，为大气物理探测研究和人工增雨作业提供了一种方便且实用的工具。     

Insights into the affine model for high-resolution satellite sensor orientation

As a model for sensor orientation and 3D geopositioning for high-resolution satellite imagery (HRSI), the affine transformation from object to image space has obvious advantages. Chief among these is that it is a straightforward linear model, comprising only eight parameters, which has been shown to yield sub-pixel geopositioning accuracy when applied to Ikonos stereo imagery. This paper aims to provide further insight into the affine model in order to understand why it performs as well as it does. Initially, the model is compared to counterpart, ‘rigorous’ affine transformation formulations which account for the conversion from a central perspective to affine image. Examination of these rigorous models sheds light on issues such as the effects of terrain and size of area, as well as upon the choice of reference coordinate system and the impact of the adopted scanning mode of the sensor. The results of application of the affine sensor orientation model to four multi-image Ikonos test field configurations are then presented. These illustrate the very high geopositioning accuracy attainable with the affine model, and illustrate that the model is not affected by size of area, but can be influenced to a modest extent by mountainous terrain, the mode of scanning and the choice of object space coordinate system. Above all, the affine model is shown to be both a robust and practical sensor orientation/triangulation model with high metric potential.