Optical spectrum based measurement of flotation slurry contents

Monitoring and control of a flotation circuit is mainly based on the information gained by assaying the process slurry lines. In flotation plants, usually an X-ray fluorescence analyzer is used to obtain the on-line assays. This article introduces the visual and near-infrared reflectance spectroscopic analysis of the process slurries as a supplementary method which complements the on-line assay information available from an X-ray fluorescence analyzer. It is shown that the spectral information can be used to accurately predict the element contents in the slurry in between successive XRF analyses. Since the spectral measurements can be taken with high frequency as opposed to the sparse X-ray fluorescence analysis, a practically continuous on-line estimate of the slurry contents is reached. These estimates can be used in the plant control to improve the overall performance of the circuits and to yield also economical savings. Additionally, the frequent monitoring of the grades can provide means to eliminate rapid disturbances in the circuits, thus improving the stability of the process.     

网络地震谣言监测系统的设计和应用

介绍了一种网络地震谣言监测系统原理,设计思路和应用情况。针对目前互联网上地震谣言频发却又难以及时检测到的问题,用软件方式取代原有的人工监视模式,实现了对网络地震谣言的全天候、高效率的监测。结合网络爬虫和知识库等技术,根据特定的匹配条件对设定范围的网址进行周期性检查,一旦发现疑似谣言信息就以短信和屏幕弹窗方式向值班人员报警。     

微量砷,锑,铋流动注射在线还原氢化物发生原子吸收连续测定法

本文采用了流动注射分析技术，用氢化物发生原子吸收分光光度法直接连续测定砷、锑、铋。在稀盐酸介质中，试样溶液中以不同氧化态存在的待测元素被硫脲、碘化钾、抗坏血酸混合还原抑制剂溶液在线还原为易生成氢化物的形式，与硼氢化钠反应生成氢化物，经我们自制的带雾化器的气液分离器分离后进入原子化器。方法稳定灵敏，再现性好，一次溶样可直接连续测定地质样品中砷、锑、铋３种元素。用本方法测定地质标样结果吻合很好，其检出限（３σ）分别为８．８４，６．９１，１２．２９×１０￣（－８）ｇ／Ｌ。相对标准偏差小于２％。     

数据仓库技术在地震信息系统中的应用

数据仓库是近年来信息领域中迅速兴起的一种技术。本文对此技木和应用进行了讨论,提出了适用于地震信息系统数据仓库的方案设计思想。     

Empowering farmers with remote sensing knowledge: A success story from the US Upper Midwest

Satellite imagery has proven potential in farm level applications, especially in the US Upper Midwest where the farm sizes are large enough to be studied using high and medium resolutions. In order for farmers to use this technology to improve their productivity and income, it is imperative that they be sufficiently exposed to the technology so that they are able to take full advantage of it. Training of farmers and ranchers in satellite imagery use started at the University of North Dakota in 2000 and has been refined over time. The basic ‘hands on’ training involves downloading imagery from the Upper Midwest Aerospace Consortium (UMAC) website, downloading and use of free visualization software programs available on the web and an introduction to the various application possibilities. Advanced training, which involves more complex extraction of useful information from digital images, is also available to those who complete the basic training. Over 500 farmers, ranchers, crop consultants and other end users have been trained through this programme and the results are beginning to show through the success stories of cost savings and environmental benefits that have emerged.     

A data based mechanistic approach to nonlinear flood routing and adaptive flood level forecasting

Operational flood forecasting requires accurate forecasts with a suitable lead time, in order to be able to issue appropriate warnings and take appropriate emergency actions. Recent improvements in both flood plain characterization and computational capabilities have made the use of distributed flood inundation models more common. However, problems remain with the application of such models. There are still uncertainties associated with the identifiability of parameters; with the computational burden of calculating distributed estimates of predictive uncertainty; and with the adaptive use of such models for operational, real-time flood inundation forecasting. Moreover, the application of distributed models is complex, costly and requires high degrees of skill. This paper presents an alternative to distributed inundation models for real-time flood forecasting that provides fast and accurate, medium to short-term forecasts. The Data Based Mechanistic (DBM) methodology exploits a State Dependent Parameter (SDP) modelling approach to derive a nonlinear dependence between the water levels measured at gauging stations along the river. The transformation of water levels depends on the relative geometry of the channel cross-sections, without the need to apply rating curve transformations to the discharge. The relationship obtained is used to transform water levels as an input to a linear, on-line, real-time and adaptive stochastic DBM model. The approach provides an estimate of the prediction uncertainties, including allowing for heterescadasticity of the multi-step-ahead forecasting errors. The approach is illustrated using an 80 km reach of the River Severn, in the UK.     

生化需氧量(BOD)测定方法进展

生化需氧量(BOD)是水质监测中最重要的指标之一。分析论述了BOD的传统测定方法、快速测定方法及在线分析检测仪器的发展,论述了各类方法的工作原理及各自的适用范围和局限性。     

Automated Ion-pair extraction and Ion-pair chromatography — a versatile method in water analysis for the determination of highly polar micropollutants

An automated HPLC method is presented which combines on-line ion-pair extraction on small exchangeable RP-C18 precolumns (RP-IPE) with ion-pair chromatography (RP-IPC). Weakly acidic herbicides — carboxylic acids, phenols, and the N-H acidic bentazone — and strong acids, e.g. aromatic sulfonic acids, can be determined simultaneously. Performance data are given. The tetrabutylammonium ion pairs of all investigated compounds are readily transferred from the RP-C18 precolumn to the analytical column by a phosphate buffer/methanol gradient. This is also true for the chlorinated phenoxy acids which, in earlier off-line extraction experiments, could not be desorbed from the RP-C18 material by the lower polar acetone. The RP-IPC is carried out at neutral pH where weakly acidic compounds appear in their stronger UV absorbing dissociated form. Compared to conventional reversed phase chromatography using an acidified eluent, the sensitivity of UV detection is markedly enhanced, especially for the phenol herbicides and bentazone. In addition, phenols can be detected more selectively because they show a second intense absorption band in the wavelength range between 280 nm and 290 nm, where there are only little interferences with the matrix. Due to miniaturization and automation, the online combination IPE/IPC allows a large sample throughput at a lower consumption of solid phase material and organic solvents. Time consuming manual steps are totally missing. The IPE/IPC technique is well suited as a screening method for fate studies of polar micropollutants, e. g. for monitoring the efficiency of different water treatment technologies. An example for balancing an activated carbon filter is presented.     

Identification of wind stress on shallow water surfaces by optimal smoothing

Using the state space approach, an on-line filter procedure for combined wind stress identification and tidal flow forecasting is developed. The stochastic dynamic approach is based on the linear twodimensional shallow water equations. Using a finite difference scheme, a system representation of the model is obtained. To account for uncertainties, the system is embedded into a stochastic environment. By employing a Kalman filter, the on-line measurements of the water-level available can be used to identify and predict the shallow water flow. Because it takes a certain time before a fluctuation in the wind stress can be noticed in the water-level measurements, an optimal fixed-lag smoother is used to identify the stress.     

Real-time forecasting of water table depth and soil moisture profiles

We present a method for real-time forecasting of water table depth and soil moisture profiles. The method combines a simple form of data-assimilation with a moving window calibration of a deterministic model describing flow in the unsaturated zone and local as well as regional drainage. The local drainage level is calibrated on-line using a moving window calibration. Assigning more weight to the last available measurements then yields a form of model adaptation that is in between on-line calibration and data-assimilation (i.e. a simplified form of Newtonian nudging). Five-day hydrological forecasts are performed based on 5-day weather forecasts, while on-line observations of phreatic level and soil moisture content are assimilated on a daily basis. Advantages of the proposed method are that it improves the real-time forecasts compared to off-line calibration and ordinary moving window calibration and that it yields physically consistent soil moisture profiles.