自动气象站各要素传感器检定结果的不确定度分析

自动气象站是由各要素的传感器和数据采集器组成的。随着时间的推移, 各传感器和数据采集器的测量误差将会发生漂移。为确保各要素观测数据的准确、可靠并具有可比性, 定期开展自动气象站的检定和校准是非常重要的。通过检定将各要素系统误差控制在允许范围内, 并对检定结果进行不确定度分析, 是考察检定结果可信程度的重要步骤。本文依据自动气象站检定规程及JJF1059-1999《测量不确定度评定与表示》的要求, 并根据检定数据, 进行自动气象站的各要素检定结果的不确定度分析, 对自动气象站检定结果可信度评估具有指导意义。     

Does measuring azimuthal variations in sap flux lead to more reliable stand transpiration estimates?

Stand transpiration (E) estimated using the sap‐flux method includes uncertainty induced by variations in sap flux (F) within a tree (i.e. radial and azimuthal variations) and those between trees. Unlike radial variations, azimuthal variations are not particularly systematic (i.e. higher/lower F is not always recorded for a specific direction). Here, we present a theoretical framework to address the question on how to allocate a limited number of sensors to minimize uncertainty in E estimates. Specifically, we compare uncertainty in E estimates for two cases: (1) measuring F for two or more directions to cover azimuthal variations in F and (2) measuring F for one direction to cover between‐tree variations in F. The framework formulates the variation in the probability density function for E (σ_E) based on F recorded in m different azimuthal directions (e.g. north, east, south and west). This formula allows us to determine the m value that minimizes σ_E. This study applied the framework to F data recorded for a 55‐year‐old Cryptomeria japonica stand. σ_E for m = 1 was found to be less than the values for m = 2, 3 and 4. Our results suggest that measuring F for one azimuthal direction provides more reliable E estimates than measuring F for two or more azimuthal directions for this stand, given a limited number of sensors. Application of this framework to other datasets helps us decide how to allocate sensors most effectively. Copyright © 2016 John Wiley & Sons, Ltd.     

探空温度传感器受太阳辐射影响的仿真分析

随着高空温度探测精度要求的日益提高,如何减小温度传感器测量误差已成为亟需解决的问题,而太阳辐射作为影响温度传感器探测性能的重要因素已成为该领域研究的热点.利用计算机仿真技术,引入太阳高度角、引线夹角2个影响因子,根据流体动力学模型模拟分析探空温度传感器从海平面上升到32 km高空时所受太阳辐射的影响,最终得到辐射误差与海拔高度的关系曲线族,仿真结果将为开展高空温度传感器误差分析提供基础依据,从而提高传感器测量准确度.     

On the mechanics of contact between a flexible transducer diaphragm located at a rigid boundary and an elastic material

In this paper we examine the mechanics of contact between a flexible elastic diaphragm and an isotropic elastic halfspace region where contact is established through the application of a normal stress. It is shown that a convenient solution for the maximum displacement and maximum flexural moment in the flexible diaphragm can be obtained by employing a variational technique. Copyright © 2006 John Wiley & Sons, Ltd.     

Local variability in temperature, humidity and radiation in the BaekduDaegan Mountain protected area of Korea

A novel embedded sensor network records changes in key climatic-environmental variables over a range of altitude in the BaekduDaegan Mountain (BDM) of Gangwon Province in Korea, a protected mountain region with unique biodiversity undergoing climate change research. The investigated area is subdivided into three horizontal north-south study areas. Three variables, temperature (T, ℃), relative humidity (RH, %), and light intensity (LI, lumens m -2 , or lux, lx), have been continuously measured at hourly intervals from June, 2010 to September, 2011 using HOBO H8 devices at 10 fixed study sites. These hourly observations are aggregated to monthly, seasonal and annual mean values, and results are summarized to inaugurate a long-term climate change investigation. A region wide T difference in accordance with altitude, or lapse rate, over the interval is calculated as 0.4℃100 m -1 . T lapse rates change seasonally, with winter lapse rates being greater than those of summer. RH is elevated in summer compared to other seasons. LI within forestland is lower during summer and higher during other seasons. The obtained results could closely relate to the vegetation type and structure and the terrain state since data loggers were located in forestland.     

Continuous-time monitoring of liquid water content in snowpacks using capacitance probes: A preliminary feasibility study

Liquid water in snowpacks rules wet snow avalanche formation, surface albedo and snowmelt runoff timing. By now, volumetric liquid water content (LWC) measurements are collected mainly with destructive methods, while continuous-time and non-invasive measurements would be preferable to track its time dynamics. Here, we assess the feasibility of continuous-time monitoring of LWC using EnviroSMART® capacitance sensors. These were conceived to track liquid water dynamics in soils, and their use in snow is evaluated here for the first time, as far as we know. A field case study was settled up in April 2013 within an Italian Alpine valley. An instrumental set up with eight capacitance sensors was installed. Two time-domain reflectrometers were added to the aim of comparison. To assist in interpreting the signal of the capacitance sensors, two laboratory tests were run, and a FEM model was implemented. This preliminary study demonstrates that capacitance sensors are sensitive to increasing LWC, although their long-term installation in snow entails the development of an air gap around them, due to localized melting, air turbulence and solar radiation absorption, which hinders following LWC variations. As a result, capacitance sensors readings are challenging to be interpreted quantitatively. Perspectives on future investigation are discussed to bring the proposed procedure towards long-term applications in snowpacks.     

利用化学传感器检测海水中的多氯联苯

为建立一种简单快捷的多氯联苯检测方法, 本研究应用化学传感器对宁波沿海重点陆源排污口及周边海水中的多氯联苯进行了检测, 采用HS-SPME-GC-MS(顶空固相微萃取-气质联用)对结果进行了验证。利用化学传感器测定海水中的多氯联苯, 在LDA(线性判别分析)中, 总判别率为99.81%。海水体积增大到5mL时, LDA 最低检测限达到了0.01ng/L。建立的模型中, 欧氏距离、相关性、判别函数法和马氏距离对样品浓度鉴别的正确率分别达到了100%、100%、92%、84%。采用Loading分析法简化了传感器阵列, 使BP神经网络总的MSE达到了5.6548e?006, 总的相关系数0.99998, 而最大误差只有1.0300e?002的水平。HS-SPME-GC-MS对海水中多氯联苯浓度的检测限最 低为0.001?g/L, 远高于化学传感器的0.01ng/L, 回收率在100%—120%之间。     

一种运动恢复结构和航位推算结合的室内行人视觉定位方法

商业和工业领域中,室内行人、车辆、机器人的位置信息正逐渐成为人们关注的热点,并随之产生了大量的室内定位技术和方法,如使用无线信号、地磁、超宽带和超声波等方式进行室内定位。然而,目前的这些室内定位方法大多需要额外辅助设备的支撑,增加了定位成本和硬件开销。视觉定位作为一种目前较为流行的定位方式,具有实施成本低、不依赖任何外界辅助设备等优势。其中,构建带有位置标签的图像数据库是视觉定位方法的关键环节,而传统的构建图像数据库方法人力开销大、时耗长。因此,本文提出一种运动恢复结构（SFM）和航位推算结合的视觉定位方法,能够快速构建图像位置数据库、大大降低人力开销。该方法主要包括2个阶段：离线阶段和在线阶段。离线阶段主要实现图像序列位置的自动标注,通过采集行走路线上的手机内置传感器信息和视频信息,提出一种多约束图像匹配方法用于视频图像的连续匹配,将匹配结果用于SFM方法,可以得到相邻图像间的运动角度,使用行人航位推算（PDR）方法标注图像序列的轨迹坐标。在线阶段使用提出的图像匹配方法计算查询图像与数据库影像间的匹配点数量,将匹配点最多的K个数据库影像位置坐标加权平均作为查询图像的定位结果。最后,分别在2种典型的室内环境下进行实验,结果表明本文方法在离线阶段位置标注的平均误差为0.58 m,在线阶段图像匹配定位的误差范围在0.2~1.4 m。     

Review of the development of laser fluorosensors for oil spill application

As laser fluorosensors provide their own source of excitation, they are known as active sensors. Being active sensors, laser fluorosensors can be employed around the clock, in daylight or in total darkness. Certain compounds, such as aromatic hydrocarbons, present in petroleum oils absorb ultraviolet laser light and become electronically excited. This excitation is quickly removed by the process of fluorescence emission, primarily in the visible region of the spectrum. By careful choice of the excitation laser wavelength and range-gated detection at selected emission wavelengths, petroleum oils can be detected and classified into three broad categories: light refined, crude or heavy refined.

This paper will review the development of laser fluorosensors for oil spill application, with emphasis on system components such as excitation laser source, and detection schemes that allow these unique sensors to be employed for the detection and classification of petroleum oils. There have been a number of laser fluorosensors developed in recent years, many of which are strictly research and development tools. Certain of these fluorosensors have been ship-borne instruments that have been mounted in aircraft for the occasional airborne mission. Other systems are mounted permanently on aircraft for use in either surveillance or spill response roles.     

气态烃快速探测系统在海洋油气勘探中的应用

气态烃快速探测系统以高灵敏度化学传感器为技术突破，与其配套装置可实现海洋烃类快速探测与现场处理一体化；可实现对不同层次，不同尺度、不同精度数据的综合解释和烃类异常的现场圈定。研制出的化学传感器及其配套装置具有：高灵敏度、高稳定性、小型轻便、低功耗、易操作、能适应恶劣海况条件，同时测定痕量气态烃和多种参数的特点。这种基于化学传感器原理的便携式高灵敏度气态烃现场测定系统，可以现场快速测定样品中的超微量甲烷、乙烷、丙烷及氢气的组分含量，并通过引入气体色谱柱和信号保真处理，使整个系统具有较好的选择性，从而实现了混合气体的高灵敏度快速分析。