Spatial variability of submarine groundwater discharge,Ubatuba, Brazil

Submarine groundwater discharge (SGD) is delivered into the oceans at various hydrogeological settings. Where coastal aquifers have spatial heterogeneous properties such as preferential flowpaths, SGD is also commonly heterogeneously distributed along the coast. SGD from a heterogeneous, fractured rock aquifer on the Ubatuba coast, Brazil has been investigated by depth profiling of ground conductivity. On spatial scales of <10 m, a significant variation in sub-surface conductivity and associated discharge rate is documented. These geophysical observations were used to identify preferential flowpaths, and to explain significant differences in average discharge rates observed in seepage meter records placed only a few metres apart from each other. This paper illustrates the utility of sub-surface conductivity measurements for accurate investigations of SGD fluxes.     

地铁车站结构振动台试验中传感器位置的优选

在对软土地铁车站结构进行振动台模型试验的过程中,对传感器设置位置的优选进行了研究,内容包括按三维问题的分析论证地铁车站结构在横向激振作用下的受力变形特征,据以确定可按平面应变问题进行分析的断面的分布范围及主观测断面的位置;按二维问题的分析论证地铁车站结构在横向激振作用下的变形趋势,据以确定观测断面上传感器设置的优选位置;以及在满足基本信息采集要求的前提下,对可供采用的信息采集通道进行优化分配的方法。成果对试验获得成功起到了保障作用,对同类试验也有参考价值。     

移动式极地大气参数测量系统I.研制与试观测

研制了移动式极地大气参数测量系统。采用温度脉动仪和三维超声风速计分别对大气湍流强度C2n进行测量。在合肥和上海两地进行了约500 h的仪器性能测试,结果显示仪器运行稳定、两种方法测得的C2n符合得很好。仪器将在2013/2014年度中国第30次南极科学考察泰山站建站期间首次对泰山站的C2n进行测量、越冬期间首次对中山站的C2n进行测量,并计划在2014/2015年度第31次南极科学考察期间对昆仑站的近地面大气湍流强度进行测量。     

经验模态分解阈值消噪方法及其在惯性导航系统数据处理中的应用

针对惯性元件误差中有色噪声影响远大于白噪声的情况,建立元件误差的分形高斯噪声模型,利用功率谱密度方法估计模型参数。基于噪声模型推导经验模分解(EMD)的各固有模态函数(IMF)分量中噪声的方差,以此估计各分量相应的阈值,建立EMD阈值消噪方法。将该方法应用于INS中,并与小波阈值法进行比较。结果表明,小波阈值法难以控制元件中有色噪声的影响,EMD阈值法与噪声模型紧密结合,能够更有效地削弱元件中的随机误差,提高INS精度。     

Langmuir–Blodgett Film of Asymmetric Calix[4]arene Derivative Modified Electrode for Voltammetric Determination of Silver

A new electrochemical voltammetric sensor, Langmuir–Blodgett (LB) film of 25,27‐dimethoxy‐26‐(N‐trichloroacetyl)carbamoyloxy‐p‐tert‐butylcalix[4]arene (DCA) modified GCE (LB_DCA–GCE), was designed and successfully used for recognition and determination of trace amounts of Ag⁺ in water. Under the optimum experimental conditions, the lowest detectable concentration of Ag⁺ reached 1 × 10^?9 mol L^?1. Moreover, LB_DCA–GCE exhibited a well‐defined response relating to the Ag⁺ with good sensitivity, selectivity, reproducibility, and long stability. The recognizing mechanism of LB_DCA–GCE for silver ion in aqueous solution was also discussed. The results show that the size of calixarene cavity may be the predominate factor affecting recognition of calixarene for silver ions.     

Fusion of RADARSAT-2 and multispectral optical remote sensing data for LULC extraction in a tropical agricultural area

In this study, we investigated the performance of different fusion and classification techniques for land cover mapping in Hilir Perak, Peninsula Malaysia using RADAR and Landsat-8 images in a predominantly agricultural area. The fusion methods used are Brovey Transform, Wavelet Transform, Ehlers and Layer Stacking and their results classified into seven different land cover classes which include (1) pixel-based classifiers (spectral angle mapper (SAM), maximum likelihood (ML), support vector machine (SVM)) and (2) Object-based (rule-based and standard nearest neighbour (NN)) classifiers. The result shows that pixel-based classification achieved maximum accuracy of the optical data classification using SVM in Landsat-8 with 74.96% accuracy compared to SAM and ML. For multisource data classification, the highest overall accuracy recorded for layer stacking (SVM) was 79.78%, Ehlers fusion (SVM) with 45.57%, Brovey fusion (SVM) with 63.70% and Wavelet fusion (SVM) 61.16%. And for object-based classifiers, the overall classification accuracy is 95.35% for rule-based and 76.33% for NN classifier, respectively. Based on the analysis of their performances, object-based and the rule-based classifiers produced the best classification accuracy from the fused images.     

Exploring the vertical extent of breaking internal wave turbulence above deep-sea topography

A mooring equipped with 200 high-resolution temperature sensors between 6 and 404 m above the bottom was moored in 1890 m water depth above a steep, about 10° slope of Mount Josephine, NE-Atlantic. The sensors have a precision of less than 0.5 mK. They are synchronized via induction every 4 h so that the 400 m range is measured to within 0.02 s, every 1 s. Thin cables and elliptical buoyancy assured vertical mooring motions to be smaller than 0.1 m under maximum 0.2 m s⁻¹ current speeds. The local bottom slope is supercritical for semidiurnal internal tides by a factor of two. Exploring a one-month record in detail, the observations show: 1/semidiurnal tidal dominance in variations of dissipation rate ε, eddy diffusivity K_z and temperature, but no significant correlation between the records of ε and total kinetic energy, 2/a variation with time over four orders of magnitude of 100-m vertically averaged ε, 3/a local minimum in density stratification between 50 and 100 m above the bottom, 4/a gradual decrease in daily or longer averaged ε and K_z by one order of magnitude over a vertical distance of 250 m, upwards from 150 m above the bottom, 5/monthly mean values of <[ε]> = 2 ± 0.5 × 10⁻⁷ m² s⁻³, <[K_z]> = 8 ± 3 × 10⁻³ m² s⁻¹ averaged over the lower 150 m above the bottom.     

数字航测相机的研究进展

本文阐述了航测相机传感器技术、位置姿态传感器技术和惯性稳定平台技术的发展概况,对具有代表性的两类数字航测相机———框幅式数字航测相机和推扫线阵航测相机的发展进行了叙述,并对国产数字航测相机——SWDC4a和SWDC5系列的研制与发展进行了介绍。数字航测相机的应用增强了对地观测能力、缩短了地理信息处理的周期、提高了对地观测的时效性。     

Development of a remotely controlled debris flow monitoring system in the Dolomites (Acquabona,Italy)

Direct measurements of the hydrological conditions for the occurrence of debris flows and of flow behaviour are of the outmost importance for developing effective flow prevention techniques. An automated and remotely controlled monitoring system was installed in Acquabona Creek in the Dolomites, Italian Eastern Alps, where debris flows occur every year. Its present configuration consists of three on‐site stations, located in the debris‐flow initiation area, in the lower channel and in the retention basin. The monitoring system is equipped with sensors for measuring rainfall, pore‐water pressure in the mobile channel bottom, ground vibrations, debris flow depth, total normal stress and fluid pore‐pressure at the base of the flow. Three video cameras take motion pictures of the events at the initiation zone, in the lower channel and in the deposition area. Data from the on‐site stations are radio‐transmitted to an off‐site station and stored in a host PC, from where they are telemetrically downloaded and used by the Padova University for the study of debris flows. The efficiency of the sensors and of the whole monitoring system has been verified by the analysis of data collected so far. Examples of these data are presented and briefly discussed. If implemented at the numerous debris‐flow sites in the Dolomitic Region, the technology used, derived from the development of this system, will provide civil defence and warn residents of impending debris flows. Copyright © 2003 John Wiley & Sons, Ltd.     

南极内陆冰盖表面地貌特征监测系统设计及应用分析

南极内陆冰盖表面的特征与冰盖表面年际降雪量、冰盖表面风速有关,冰盖表面地貌特征主要包括雪面粗糙度、雪层软硬度,这些特征对内陆车队行进过程中的设备运输具有重要的参考价值。文中提出了车载自动化监测冰盖雪面特征的方法,并进行了监测系统的设计与数据分析;该系统包括以雪地车颠簸幅度代表的雪面凹凸程度(即雪面粗糙度),以GPS模块监测车辆行进距离,以激光测距监测雪地车车辙深度来表征雪面软硬度。通过数据采集系统的实时监测软件平台,实现了冰盖表面地貌特征的监测;该系统分别于2012年11月和2014年11月在中国第29次南极和31次南极考察中进行了监测应用,通过对以上监测数据的分析,初步给出了中山站至昆仑站沿途的冰盖表面粗糙度及雪面软硬度结果。