基于测量机器人的GPS天线相位中心影响检测法

在GPS高精度定位中,天线相位中心影响是制约精度的一个不可忽视的因素。介绍国外最新发展的机器人测量法,推导其原理和实施步骤,并给出数据解算中应用天线相位中心检测结果的方法和流程。本研究对提高GPS测量定位的精度,以及开展基于我国卫星导航系统的接收机相位中心的检测,都具有重要的参考意义。     

江宁台井下地电阻率电极接地电阻分析

电极是否稳定可靠是地电阻率观测系统的重要指标之一,主要通过测量电极的接地电阻大小来评价其状态。首先,分析现有测量方法,认为线路加电测量法更合理,提出考虑电缆线电阻的线路加电测量法;其次,采用该方法和接地电阻测试仪测量方法,测量江宁台多套地电观测系统电极的接地电阻,比较分析后者的结果误差;第三,讨论其接地电阻超出标准、同深度不同电极接地电阻差异及同井孔不同深度电极接地电阻差异,其原因可能与地下低电阻率区域及电极周围的地层湿度、介质的孔隙度有关,并分析了加电测量法存在的不足;最后,当接地电阻超标时,应该依据其变化幅度来判定电极是否稳定可靠。     

浅谈气象电子设备的检修方法

检修电子设备时,不要急于通电检查。首先应向使用者了解电子设备故障前后的使用情况(故障发生在开机时,还是在工作中突然或逐渐发生的,有无冒烟、焦昧、闪光、发热;故障前是否动过开关、旋钮、按键、插件等）及气候等环境情况。     

海水油荧光测量方法实验研究

根据荧光测量方法的原理,采和双光路,双通道及单片微机控制,数据自动采集的技术,于１９９７年研制成功用于海洋现场探测的单波段水中油荧光计。应用该水中油荧光计进行了海水中微量油份的测量实验研究。     

辽宁锦州市土地利用动态遥感监测方法应用研究

文章以辽宁锦州市为研究区,以SPOTS为主要遥感数据源,以1:10000地形图(或土地利用现状图)、野外GPS测量点为几何控制点,应用全数字摄影测量法,进行遥感影像的精确配准、纠正与融合.制作高精度的正射影像图;在GIS支持下,叠合基期土地利用现状图等非遥感数据,采用图像差值法、光谱特征变异法和人机交互解译法,增强提取土地利用变化信息,通过实地调查与核实,取得了良好的应用效果.     

Measurements of coupled fluid and sediment motion over mobile sand dunes in a laboratory flume

The relationship between turbulent fluid motions and sediment particle motions over mobile sand dunes was investigated by using a laser Doppler velocimeter and an acoustic backscatter system in laboratory experiments performed at the USDA-ARS-National Sedimentation Laboratory. Profiles of acoustic backscatter from particles and at-a-point turbulence data were collected while translating both measurement devices downstream at the speed of mobile dune bedforms. The resulting data set was used to examine the frequency （recurrence frequency） at which the fluctuating backscatter and fluid velocity signals exceeded magnitude thresholds based on the standard deviation （σ） of the local velocity and the magnitude the acoustic signal resulting from backscatter from suspended particles. The slope of the downstream and vertical velocity recurrence frequencies generally indicated a gradually increasing recurrence time with increasing elevation. The recurrence frequency for acoustic backscatter data was not strongly variable with elevation. The closest correspondence between the recurrence frequencies of sediment backscatter and vertical velocities at the 1σ magnitude threshold was in a region defined by X/L〈0.4 and y〈6 cm. The downstream velocity was most closely related to backscatter in a small region at 0.4〈X/L〈0.8 and less than 3-4 cm from the bed.     

自动气象站风向测量系统现场校准方法改进的探讨

研究了一种现场校准自动气象站风向测量系统的方法,即静态三点测量法。目的在于解决目前对风向示值校准角度覆盖不全,即风向校准区间缺测问题。根据格雷码盘式风向传感器的风向值对应码的编码原理和规律,采用理论分析和实验对比的方式论证该校准方法有效性和可靠性。在对风向测量系统的现场校准中,该方法能够很好的解决现场风向校准的区间缺测问题,并且校准数据准确可靠,在现场实际运用中切实可行。对于现行的室内检定风向示值,也建议采用该方法。     

两次电导率测量法测定染料废水中的氯离子

配制两份相同体积的样品溶液,一份加过量的ＡｇＮＯ３,另一份不加ＡｇＮＯ３,根据两分溶液电导率的差值与Ｃｌ＾－的浓度的关系,建立了测定Ｃｌ的方法,该法用于染料废水中Ｃｌ＾－测定,其ＲＳＤ≤２．６７％,加标回收率为９６．７％和１００．％,方法简单快速。     

Numerical simulation and validation of ocean waves measured by an Along-Track Interferometric Synthetic Aperture Radar

A new nonlinear integral transform of ocean wave spectra into Along-Track Interferometric Synthetic Aperture Radar （ATI-SAR） image spectra is described. ATI-SAR phase image spectra are calculated for various sea states and radar configurations based on the nonlinear integral transform. The numerical simulations show that the slant range to velocity ratio （R/V）, significant wave height to ocean wavelength ratio （Hi2）, the baseline （2B） and incident angle （0） affect ATI-SAR imaging. The ATI-SAR imaging theory is validated by means of Two X-band, HH-polarized ATI-SAR phase images of ocean waves and eight C-band, HH-polarized ATI-SAR phase image spectra of ocean waves. It is shown that ATI-SAR phase image spectra are in agreement with those calculated by forward mapping in situ directional wave spectra collected simultaneously with available ATI-SAR observations. ATI-SAR spectral correlation coefficients between observed and simulated are greater than 0.6 and are not sensitive to the degree of nonlinearity. However, the ATI-SARoPhase image spectral turns towards the range direction, even if the real ocean wave direction is 30. It is also shown that the ATI-SAR imaging mechanism is significantly affected by the degree of velocity bunching nonlinearity, especially for high values of R/V and H/2.