几种液位计在沉降槽上的应用

通过对沉降槽上应用过的几种液位计的测量原理及使用情况分析，说明了吹气式液位计和超声波液位计测量的缺陷及采用雷达液位计的必要性，并指出：雷达液位计是今后物位测量的发展方向。     

非接触式外测液位计在液氯储槽液位测量中的案例分析

在氯碱生产过程中,当液氯储罐遇到液位计测量液位不准确的问题时,可以通过使用西安定华公司生产的ELL外测式液位计来有效解决液氯储罐液位测量不准的问题。文中介绍了结霜管液位计、雷达液位计和ELL外测液位计的使用效果对比,认为采用外测液位计测量液位的方式是一种先进、科学、安全的有效方法。     

改进型雷达液位计在槽体液位测量中的应用

雷达液位计在测量液位过程中有着众多优点,但对于易挥发结晶介质的液位测量却存在不同程度的局限性。为增强雷达液位计的使用性能,通过对生产过程中使用的雷达液位计在对槽体液位测量中出现的一系列问题进行深入分析,并结合雷达液位计的测量原理和结构特点,提出了一种利用雷达液位计与导波管相结合的测量方法,为化工企业生产中雷达液位计的使用提供了参考。该改进型雷达液位计结构简单,易于安装与维护,有效避免了槽体液位测量中液位波动、测量介质等因素的影响,使测量精度提高了10倍以上,抗干扰能力大大增强,确保了测量结果的稳定性和准确性。该改进型雷达液位计的创新性在于结合了导波管与雷达液位计的优点,成功解决了雷达液位计在液位测量过程中的局限性。该研究成果解决了槽体液位测量过程中常见的问题,同时为石化、焦化、化工等行业生产过程中雷达液位计的使用方法提供了一些启示。     

隔离模块在吹气式液位监测系统中的设计

针对分布式控制系统（DCS）控制柜现场调试中出现的无法采集吹气式液位计变送器信号问题,对DCS控制柜各关键模块进行了全面测试排查和分析,确定了故障模块及无法采集信号的原因,提出了5种可行的工程解决方案。综合考虑工程项目进度、成本等多方面因素,对5种解决方案的优势和劣势分别进行了分析和对比,确定了对工程项目影响较小的新增隔离模块解决方案,并对DCS控制柜进行了设计修改。对设计修改后的DCS控制柜开展了功能测试和试验验证。试验结果表明,DCS控制柜能够正常采集吹气式液位计变送器信号,系统运行稳定,满足设计和技术规格书要求。新增隔离模块技术解决方案属于吹气式液位监测系统的成功应用,对后续工程项目的吹气式液位监测系统设计具有指导价值,对控制柜调试中出现的类似问题解决具有重要参考意义。     

常用酸槽液位计的性能比较

对常用酸槽液位测量方法进行了比较,讨论何种液位计（晶体管防爆液位计、吹气法液位计、妙声力超声液位计）是酸槽液位测量的理想选择。     

基于现场总线型雷达液位计的研究与应用

介绍了雷达液位计的工作原理及天线种类,详细阐述了总线型雷达液位计的系统结构,结合实际对使用中的注意事项及故障处理进行说明。     

论氨球罐液位计选型

生产出的液氨一般存储在球罐里,而液氨具有可急剧挥发的特性,存在液位测量比较困难的问题。分别介绍了几种液位计,如雷达液位计、差压液位计、磁翻板液位计、伺服液位计在使用过程中存在问题,选出比较合理的测量液位计。     

外测式液位计在石油化工生产中的应用

外测式液位计采用隔离式测量,适合在特殊场合使用;自校准设计提高测量精度;安装简便,维护量小,使用安全可靠.本文叙述了外测式液位计的工作原理和特点,根据与其他液位计实际使用结果对比,表明外测式液位计在特殊使用条件下,有一定推广使用价值.     

新型液位检测技术的现状与发展趋势

文章介绍了工业生产过程中采用的光纤液位计、磁致伸缩液位计、音叉液位限位开关、差压式液位计、雷达液位计、伺服型浮子液位计等几种较新的液位检测仪表及其检测方法,并对几种液位计的特点进行了分析比较。文章最后指出,液位自动检测技术一方面需采用新的测量原理,开发新的液位检测仪表,扩大检测的手段,另一方面需朝着微机化和智能化方向发展。     

吹水式液位计在工业生产中的应用

针对吹水式液位计在应用中出现的问题,在介绍其结构和工作原理的基础上,结合现场实际分析了造成吹气量计量不准确的原因,提出了相应的实施改进措施和维护要求,经实施后收到了良好的经济效益。     

导波雷达液位计检测单元的研究与设计

针对现代工业的测量要求,提出了一种导波雷达液位计的硬件设计方案。考虑到液位测量死区比较小、测量精度比较高,且安装环境比较恶劣等因素,采用超宽带雷达脉冲作为脉冲发射源,并以双杆作为传播介质。同时,为了解决因传播距离比较短而造成的测量时间和回波幅值较小这一问题,引入了基于等效时间采样和相干测量方法的接收系统。仿真结果表明,该设计可用于导波雷达液位计,满足测量要求,并具有良好的性能。     

SmartRadar液位计在罐区的应用

测量精度是储量管理系统的主要指标,雷达是储罐液位测量的最新应用技术之一。Enraf公司的SmartRadar雷达液位计是一个采用了数字平面技术的智能雷达液位计,它大大提高了测量精度。对其测量原理和结构特点进行了介绍,并描述了储罐计量控制系统的组成,进而分析说明了雷达液位计在罐区测量中的优势。     

大罐液位仪的现状和发展趋势

本文分析了大罐液位仪的现状，指出了磁致伸缩液位仪、超声波液位仪、射线液位你、雷达液位仪等的特点，并探讨了大罐液位仪的发展趋势。     

基于CAN总线的雷达液位仪通信模块设计

雷达液位仪是一种非接触式的高精度液位测量仪表。针对现有雷达液位仪不具有现场总线通信方式的现状，设计了基于CAN总线的雷达液位仪通信模块，给出了硬、软件的设计方案，并指出了需要注意的问题，为组建基于CAN总线的液位测量系统打下了良好的基础。实验表明，该通信模块具有结构简单、工作稳定可靠、通信速率高等特点。     

OTTRLS雷达水位计在山区性河流中的应用探讨

瓦窑水文站水流湍急,坡陡且垂直高差大,传统的浮子式或压力式水位计存在附属设施施工困难,观测过程历时较长且难度大等缺陷,为此引进OTTRLS高精度雷达水位计用于水位观测.为保证瓦窑水文站水位资料观测精度及资料序列的一致性,在分析OTTRLS雷达水位计测量原理基础上,收集同时期雷达水位计遥测与人工水尺观测的492组数据进行...     

非接触式水位计校准装置的研制与应用

为解决我国水利行业大量使用的超声波、雷达式等非接触式水位计的测量准确度问题,研制开发出一种非接触式水位计实验室校准装置。通过分析非接触式水位计的测量误差源,介绍非接触式水位计校准装置数据采集与控制、数据测量、升降、人机界面等子系统的设计,并对装置的计量误差进行测试分析,对实现的功能进行阐述。经过应用测试,验证该装置校准精度在1 mm以内,适应波束角15°,能很好地满足非接触式水位计的实验室校准工作,为行业内大量应用的非接触式水位计的校准提供新的手段,为水位测量仪器的数据准确性提供技术保障。     

Integrated analysis of PALSAR/Radarsat-1 InSAR and ENVISAT altimeter data for mapping of absolute water level changes in Louisiana wetlands

Interferometric Synthetic Aperture Radar (InSAR) has been used to detect relative water level changes in wetlands. We developed an innovative method to integrate InSAR and satellite radar altimetry for measuring absolute or geocentric water level changes and applied the methodology to remote areas of swamp forest in coastal Louisiana. Coherence analysis of InSAR pairs suggested that the HH polarization is preferred for this type of observation, and polarimetric analysis can help to identify double-bounce backscattering areas in the wetland. ENVISAT radar altimeter-measured 18-Hz (along-track sampling of 417 m) water level data processed with regional stackfile method have been used to provide vertical references for water bodies separated by levees. The high-resolution (~ 40 m) relative water changes measured from ALOS PALSAR L-band and Radarsat-1 C-band InSAR are then integrated with ENVISAT radar altimetry to obtain absolute water level. The resulting water level time series were validated with in situ gauge observations within the swamp forest. We anticipate that this new technique will allow retrospective reconstruction and concurrent monitoring of water conditions and flow dynamics in wetlands, especially those lacking gauge networks.     

The impact of raindrop drift in a three-dimensional wind field on a radar–gauge rainfall comparison

There are many causes for the discrepancies between weather radar and rain gauges, and among these, displacement of raindrops due to wind drift – which is especially a problem with high-spatial resolution weather radar – is largely ignored in the published literature. This is mainly due to the lack of high-resolution three-dimensional wind fields and feasible treatment of the raindrop size distribution (DSD). In this study, a new systematic approach is proposed to explore the radar–gauge relationship under the wind influence. The mass-weighted mean diameter of raindrops is derived for each radar grid from the DSD data. The reanalysis project ERA-40 data of the European Centre for Medium-range Weather Forecasts (ECMWF) are used to drive the numerical weather research and forecasting (WRF) model to generate high-resolution hourly three-dimensional wind fields. Trajectories and displacements of raindrops are then computed using a three-dimensional motion equation from the given radar beam height to the ground surface. Based on the radar rainfall surface interpolated by the bicubic spline method, the correlation of the radar–gauge pairs is used to validate the results. A case study with 20 storm events in the Brue catchment in South West England is chosen to evaluate the proposed scheme. It has been found that when wind drift is taken into account, the correlation coefficient in hourly gauge–radar comparisons can be enhanced by up to 30% and the average correlation coefficient for an event can be improved by 10%. However, there are still some situations in which the scheme fails to work, indicating the complexity and uncertainties in tackling this challenging problem. Further studies are needed to explore why those cases cause problems to the scheme and how it could be improved to cope with them.     

基于神经网络分类的星载雷达高度计近岸回波处理方法

对HY-2B卫星雷达高度计香港近岸波形进行了统计分析,将近岸非海洋波形分为似海洋波形、似陆地波形、单锥波形。在此基础上,提出基于神经网络分类的星载雷达高度计近岸回波处理方法,提取7项波形特征作为回波分类的输入,构建误差逆传播神经网络（Back propagation,BP）,不同的波形类别对应不同的重跟踪方法。其中针对似海洋波形,提出异常波峰剔除的重跟踪方法,有效提高了似海洋波形的重跟踪成功率。使用Jason-2卫星雷达高度计近岸数据进行实验,结果表明重跟踪成功率和数据有效性均得到提高;利用HY-2B卫星雷达高度计直湾岛海域数据进行实验,并将验潮站数据作为参照标准,重跟踪得到的海面高与验潮站的海面高进行差值比较,该方法得到差分序列的标准差为6.5 cm,优于传统处理方法的14.5 cm。     

Automated Bayesian quality control of streaming rain gauge data

Radar-rainfall data are being used in an increasing number of real-time applications because of their wide spatial and temporal coverage. Because of uncertainties in radar measurements and the relationship between radar measurements and rainfall on the ground, radar-rainfall data are often combined with rain gauge data to improve their accuracy. However, while rain gauges can provide accurate estimates of rainfall, their data are sometimes corrupted with errors caused by the environment in which the gauges are deployed. This study develops a real-time method for identifying measurement errors in rain gauge data streams. This method employs a dynamic Bayesian network (DBN) model of the rain gauge data stream to sequentially forecast the next rain gauge measurement from both the rain gauge and weather radar data streams and a decision rule-based classifier to identify data errors. Because of the uncertainty in the relationship between the radar and rainfall measurements, this method uses a statistical learning method (expectation maximization) to determine the best parameters for this relationship, given an adaptively sized moving window of previous measurements. The performance of the error detector developed in this study is demonstrated using a precipitation sensor network composed of five telemetered tipping bucket rain gauges and a WSR-88D weather radar. Through an analysis using synthetic errors, the false alarm rate and false negative rate were calculated to be 0.90% and 1.5%, respectively.