Operative Calibration Methodology of a TDR Sensor for Soil Moisture Monitoring under Irrigated Crops

Time domain reflectometry (TDR) is more and more frequently used for soil water content measurements in replacement of other techniques as neutron probe. Such observations that can be continuously collected on dataloggers are convenient for monitoring water fluxes under irrigated crops. Though relationships to calculate volumetric water content from analysis of TDR signal and collected data are published in literature or given by manufacturers for different commercialized devices, the results are not satisfactory for many soils and specific calibrations are required. In replacement of the traditional calibration method, two rapid operative computer assisted methods are proposed. The first one is based on drip moistening of a cylindrical sample of disturbed dry soil in which a TDR sensor is vertically embedded. The second one uses the same cylindrical sample wetted close to saturation in which a TDR sensor is inserted step by step during measurements. The data from the two methods were fitted using second degree models. These results are in good agreement with conventional calibration method or gravimetric field measurements of soil water content. Utilization of short time step TDR measurements for monitoring soil water storage under a furrow irrigated corn shows consistent observations with water applications or uptakes by crop. Field comparison with neutron probe and gravimetric measurements corroborate the need of a specific calibration for the soil studied in this paper though its clay content is about 20%.     

Soil moisture assessment by means of compressional and shear wave velocities: Theoretical analysis and experimental setup

In previous works, the authors presented the outline of a method for measuring the moisture content in agricultural soils via elastic waves, along with experimental results obtained on a specimen of sandy soil. This work illustrates other aspects and results of the research, regarding both the underlying theory and the design and realization of an improved measurement system. Firstly, the derivation of the simplified equations which are at the basis of the moisture measurement is thoroughly illustrated and discussed, starting from the more complex (and generally unmanageable) equations of elastic waves in unconsolidated porous media. The analysis suggests that by measuring the velocities of low-frequency compressional and shear waves in soils, it is possible not only to measure the water content, but also the uniformity in the water distribution. Secondly, the design and the practical realization of an experimental setup, which is able to measure the velocity of compressional and shear waves in soils, is illustrated in detail. The use of custom-built compressional and shear waves electromechanical actuators, together with geophones, low noise preamplifiers, and suitable signal processing techniques, brought to the realization of an effective and reasonably accurate measurement system.     

Estimation of Temporal Changes of Volumetric Soil Water Content from Ground-Penetrating Radar Reflections

Time series of ground-penetrating rader traces are used to monitor temporal changes of soil water content down to about 1.5 m. The results are compared with high-resolution time series of time-domain reflectometry measurements at a few locations in the soil profile. We find a reasonable agreement between the two approaches and discuss the differences in terms of their respective limitations.     

Improving the integrity of IR based online moisture measurement used in the paper and board industry

The automatic control of product moisture content in the paper industry is based upon online moisture measurement. Furthermore, the automatic control of other quality variables such as coat weight may also rely on the moisture measurement. The integrity of infrared radiation (IR) based online moisture measurement systems was studied by performing basic calibrations at the mills with references sealed between two glass plates. The calibrations were performed according to the EN ISO/IEC 17025 standard which is a requirement for calibration laboratories. The observed measurement errors were 2.9% moisture in the first time calibrations at the 95% confidence level. It is demonstrated that these errors can be reduced to under 0.5% moisture by applying traceable methods in the basic calibration, thus improving the integrity of online moisture measurements. Also a standardised algorithm, based on the experience from the performed calibrations, is proposed to ease the adjustment of different moisture measurement systems.     

土壤水分测量的研究

介绍一种土壤水份测量装置。它采用电导法原理，利用优良的交流检测电路和单片机系统，结构简单，操作方便，精度高，成本低，稳定性好     

基于神经网络的软测量模型及应用

本文提出了一种新的基于神经网络软测量模型及算法,为复杂测量系统中软测量建模提供了一种有效的途径。应用结果表明采用该算法可获得较高的测量精度。     

基于DSP的中药丸料湿度密度在线检测系统

设计与研制一种能在现代化中药制药生产线上在线连续测量中药丸料湿度与密度的微波检测系统。系统包括三个组成模块：微波信号源模块，微波谐振腔，数据处理模块。其中，微波谐振腔是专门设计用于中药丸料湿度与密度检测的中心开通孔的金属谐振腔，当中药丸料通过微波谐振腔的中孔时，丸料密度及湿度均令谐振腔的谐振频率产生偏移和功率衰减，数据处理模块据此计算中药丸料的湿度与密度。为提高检测精度，采用模糊聚类算法对实验数据进行分组，对金属谐振腔的频偏和功率衰减特性进行建模，并利用DSP设计并实现了中药丸料湿度与密度的在线检测。现场调试表明：该检测系统适宜于现代化中药制药生产线上的湿度连续在线测量，其检测精度达到93％以上。     

基于SVM的多传感器信息融合算法

支持向量机(Support Vector machine,简称SVM)是一种基于结构风险最小化原理,具有很高泛化性能的学习算法。针对工业多传感器测控系统中,被测系数与相关参数之间存在有较大的非线性和模糊关系,提出了一种基于支持SVM的多传感器信息融合模型及算法。为小样本、非线性、高维数一类多传感器信息融合问题的建模提供了一种有效的途径。通过对“纸张水份在线测量系统”应用表明,基于SVM的多传感器信息融合模型及算法在测量精度和推广性能上都具有一定的优越性。     

河沙电特性与其含水量的关系

本文利用数字电桥测量两种粒度不同含水量下河沙的电阻、电容和品质因数值，利用MT智能测水仪测量了其综合电特性，得到了两种粒度河沙的各单独电特性及综合电特性与其含水量的对应关系，为利用电特性测量不同粒度河沙的含水量提供了理论基础。     

A new 1.4-GHz soil moisture sensor

Moisture content determination in agriculture and civil engineering is a common process which needs special sensors with high accuracy, durability and compatibility with the measurement environment. A new 1.4-GHz soil moisture sensor using microstrip transmission line is presented. The proposed sensor consists of two separate parts: (1) A sensor head, which is a microstrip transmission line to be placed in the soil, and (2) an electronic transceiver which sends a sinusoidal wave into the sensor head at one end of the transmission line, and receives the traveled wave from the other end. Transmitter is basically a Colpitts oscillator, and the receiver is a phase detector that measures the phase shift due to velocity variation caused by the moisture content of soil. At a certain frequency, the velocity of a microwave traveling through a media depends on the permittivity of that media. The proposed sensor is implemented and tested on one sample of typical soil. The main advantages of the proposed sensor are its high accuracy, quickness of measurement, its low cost and ease of implementation. Since the sensor has low power consumption, it can be recommended for low-power applications such as wireless sensor network.     

基于微波谐振器的谷物湿度检测系统

设计和研制一种能连续测量谷物湿度的微波检测系统.提出利用微波谐振器的干扰特性测量谷物的湿度,并设计专用于谷物湿度检测的中心开通孔的微波谐振器.当谷物颗粒通过微波谐振器的中孔时,其质量和湿度都令谐振器的谐振频率产生偏移和功率衰减,谷物的质量和湿度两者所引起的谐振频率偏移和微波功率衰减是相对独立的,在同一湿度下谷物的质量仅仅与微波功率的衰减量有关.因此在得到谐振频率的偏移量和微波功率的衰减量后,就可以计算谷物的湿度.在大量试验的基础上,对试验数据进行模糊聚类,从而对微波谐振器的频偏和功率衰减特性进行建模,据此设计并研制了谷物湿度的微波连续检测系统.试验调试表明:该检测系统适宜于谷物的连续湿度检测,检测精度达到92%以上.     

煤泥利用现状及分析

随着煤炭行业规模化和集中化程度的提高,煤泥产量也大幅增加.由于煤泥不能被充分利用,造成了资源堆积和污染,因此如何有效利用这些资源变得刻不容缓.本文对国内煤泥利用的现状和问题进行了分析,探讨了煤泥掺烧、煤泥制浆燃烧以及型煤型焦等具体应用的优缺点,发现阻碍煤泥大规模利用的关键是其含水率,并就目前国内的煤泥干燥措施及存在的问题进行了讨论分析,为促进今后煤泥的利用提出了相关建议.     

A non-steady-state probe measurement method to determine heat conductivity, heat capacity as well as moisture in solids and bulk materials

It is important to know the heat conductivity coefficent for an effective use of energy, for quality control of many products or numerical simulation of heat transfer problems. Measurement of heat conductivity should be realized with high reliability and accuracy, in a short time and with low expenditure both in the laboratory and in situ at the production process, to be able to influence the current process. A non-stationary probe and measurement method developed at Dresden University (Institute of Thermodynamics and Human Engineering) allows the determination of heat conductivity, heat capacity as well as water content of solid and bulk materials. Comparative measurements on standard materials and expert opinions of various institutions confirm the high accuracy and the reliability of the non-steady-state probe measurement device also in so called “problematic” materials.     

储粮温度水分自动测试系统设计

本文利用半导体温敏器件实现储粮温度检测,依据高频阻抗原理实现粮食水分快速检测,研制了融温度、水分快速检测于一体的自动测试系统,系统已在多个粮库中投入使用。     

A Method of Quantitative Measurement of Fluorescence Intensity by Confocal Laser Scanning Microscopy

We present a method of quantitative measurement, by laser scanning microscope, of intensity of fluorescence in assays on concentration of fluorochromes in a sample. This method can be used to evaluate the DNA content or the concentration of any protein, marked by an appropriate fluorescent dye, in single cells or groups of cells, isolated or in a tissue. Confocal laser scanning microscopy provides optical serial sections through thick biological sample that give accurate information about the intensity of fluorescence. The method we propose consists in scanning the sample by juxtaposition of optical sections and displaying it as a suitable projection. Multiplying the fluorescence intensity in such projection by the number of sections we obtain an estimate of the concentration of fluorochrome in the sample. We tested this method on fluorescent beads and on biological samples stained for DNA. We evaluated and corrected the measure for the photobleaching effect and for the beam theoretical distortion. Our results show that this method is accurate and suitable to compare samples of variable thickness and for multiple stained samples, and is less time consuming than the method based on the scanning of the sample according to the Nyquist principle.     

Microwave Aquametry: An Effective Tool for Nondestructive Moisture Sensing

Moisture content in solid, granular and pulverized materials is one of the most important material parameters during production, trading, processing and storage of those materials. Recent advances in application of microwave measuring techniques to nondestructive determination of moisture content are reviewed, with a special emphasis being put on a newly developed concept of a density-independent calibration. It is concluded that those techniques provide accurate, fast and nondestructive means for moisture content testing in such materials and satisfy requirements of automated industrial processes, scientific laboratories, material mass storage, personnel safety and long-term transport.     

微波谐振腔含水率传感器的设计方法

构建了含水混合物介电特性模型,设计了基于此模型的开路同轴谐振腔传感器,并指出影响其传感特性的两个主要参数是保护盖介电常数和空载谐振频率.针对此问题,利用MATLAB对保护盖介电常数和空载谐振频率对传感器传感特性的影响进行了仿真和分析.加工了具有不同谐振频率的含水率传感器及不同介电常数的保护盖.实验结果表明,本文提出的模型能够很好地指导传感器的设计,同时选取Al2O3制作的保护盖和空载谐振频率为2.5G的同轴谐振腔具有较好的测量效果.     

磺基水杨酸分光光度法测定土壤、沉积物中铁量

文章介绍了磺基水杨酸分光光度法测定土壤、沉积物中铁量,建立了盐酸-硝酸的消解体系、磺基水杨酸分光光度法,对土壤、沉积物中铁量进行测定的新方法,分析步骤合理。实验结果表明此分析方法操作简便,选择性好,灵敏度高,低环境污染,测试结果令人满意。对标准参考样品测定数据显示,本方法准确可靠,精度好。详细介绍了实验方法的过程,对实际工作中的分析者有一定的指导意义。