摘要 :
Efficient and highly automated metallurgical processes require the on-line control of coke moisture which assures high steel quality and fuel economy. The present paper dealt with the feasibility study of the Fast Neutron and Gamm...
展开
Efficient and highly automated metallurgical processes require the on-line control of coke moisture which assures high steel quality and fuel economy. The present paper dealt with the feasibility study of the Fast Neutron and Gamma-ray Transmission (FNGT) technique for the determination of the moisture content of coke in a hopper-mounted gauge arrangement. In the experimental assembly, a Pu-Be source was used. Two separate detectors: φ25x120 mm ~3He (surrounded by paraffin moderator) and φ100x100 mm Nal(Tl) were applied. The temperature of the moderator was controlled and a suitable correction of the neutron count rate was done as the hydrogen H capture cross-section shows a 1/v dependence, where v is the neutron velocity. The optimisation of the FNGT arrangement was done by the modelling calculations using MCNP 4C code and was focused on obtaining a high sensitivity of the transmitted neutron flux to the moisture changes and on lowering the neutron-counting error, both leading to a more accurate humidity determination. Laboratory measurements were carried out for lump-coke and crushed-coke samples, with added moisture up to 8 wt.% and 17.1 wt.% respectively, and showed a good agreement between the moisture content determined from the FNGT measurements and the moisture determined from an oven-drying method.
收起
摘要 :
Microwave resonant cavities have been studied as possible sensors for rapid determination of the mass or weight of perturbing dielectric objects of given permittivity and density, but of arbitrary shape, inserted into the cavity. ...
展开
Microwave resonant cavities have been studied as possible sensors for rapid determination of the mass or weight of perturbing dielectric objects of given permittivity and density, but of arbitrary shape, inserted into the cavity. Tracking the coordinates of the peak of the resonant curve with and without the object, i.e. measuring shift of resonant frequency and change in the cavity Q-factor, provides information that together with a calibration equation is sufficient for the object mass or weight determination. During the calibration procedure, the parameters of the empty cavity, as well as the permittivity and the specific gravity of the object material must be known. The measurement technique does not, in principle, require any contact between the object and the measuring system, and measurements can be rapid and reasonably accurate. Basic principles of the shape-independent measurements are presented, and experimental results are given for common plastic objects of irregular shapes measured in resonant cavities operating at 640 MHz and 1.7, 2.5 and 3.2 GHz. [References: 15]
收起
摘要 :
This study has applied the Nondominated Sorting Genetic Algorithm II (NSGA-II) in a two-step assimilation procedure to jointly assimilate brightness temperature into a radiative transfer model and soil moisture into a land surface...
展开
This study has applied the Nondominated Sorting Genetic Algorithm II (NSGA-II) in a two-step assimilation procedure to jointly assimilate brightness temperature into a radiative transfer model and soil moisture into a land surface model. The first assimilation procedure generates a time series of soil moisture by assimilating brightness temperature from the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) into the Land Parameter Retrieval Model (LPRM). The second procedure generates assimilated soil moisture by assimilating the soil moisture from LPRM into the Canadian Land Surface Scheme (CLASS). Note that the assimilated soil moisture was generated by merging two soil moisture estimates: one from LPRM and the other from the CLASS simulation. The assimilated soil moisture is better than using the soil moisture determined either from the satellite observation or the land surface scheme alone. This method provides improved model state and parameterizations for both LPRM and CLASS with the aim to facilitate real-time forecasts when satellite information becomes available. Application of this framework to the Brightwater Creek watershed in southern Saskatchewan illustrates the utility of the joint assimilation framework to improve a time series of soil moisture estimates. The estimated soil moisture datasets were evaluated over an agricultural site in southern Saskatchewan using in situ monitoring networks. These results demonstrate that soil moisture generated from assimilation of brightness temperature could be improved by incorporating it into a land surface model. A comparison between the assimilated soil moisture and in situ dataset demonstrates an improvement in accuracy and temporal pattern that is accomplished through the assimilation framework.
收起
摘要 :
Various methods for determining the moisture content in wood chips were tested and compared, focusing particularly on rapid testing. Methods based on the drying effect showed the least deviations from the reference method (105∞ C...
展开
Various methods for determining the moisture content in wood chips were tested and compared, focusing particularly on rapid testing. Methods based on the drying effect showed the least deviations from the reference method (105∞ C in the drying oven). Capacitive or infrared-reflective measuring operations (for measuring a continuous flow) partially showed promising results after calibrating the wood fuel accordingly, indicating some suitability for stationary applications, too. The IR-reflection principle works independently from any bulk density variations.
收起
摘要 :
A commercially available radio-frequency (RF) application unit was used to estimate the dry matter (DM) content of chopped maize. Chopped maize with a known DM content was placed in the application chamber of the RF unit and a def...
展开
A commercially available radio-frequency (RF) application unit was used to estimate the dry matter (DM) content of chopped maize. Chopped maize with a known DM content was placed in the application chamber of the RF unit and a defined power was applied until there was no more power reflected due to an automatic matching network. At this point, the voltage between the capacitor plates and the device-specific parameters, load position and tune position, were recorded. By means of regression analysis, it was possible to clearly explain the variance of the DM content with the parameters measured. However, the relations developed were especially unsatisfactory when different sample weights and densities were included in the analysis. A good adaptability of the model was achieved by using the mass of water as a dependent variable. Calculating a regression equation with data from one farm and estimating the water mass in the samples from another farm using this equation, the correlation coefficient between the real and estimated water content was 0.98.
收起
摘要 :
As it has been already mentioned in the first part of this work devoted to the moisture determination in barley, green and finished malt, the thermogravimetric determination of moisture content in natural samples by means of the H...
展开
As it has been already mentioned in the first part of this work devoted to the moisture determination in barley, green and finished malt, the thermogravimetric determination of moisture content in natural samples by means of the HR 83 moisture analyser of the company Mettler -Toledo is based on the principles of halogen warm-up and automatic monitoring of the course of the drying curve. This part describes the results related to the elaboration and validation of the method for thermogravimetric moisture determination in whole hops and hop products. At the same time, comparisons of results obtained by this method with the results obtained by the official method of moisture determination in hops and hop products were made (EBC 7.2, MEBAK 5.2.3 and IOB 2.2). Based on the findings it can be stated that the results of the thermogravimetric method coincided with the results obtained by the official method and therefore this moisture meter can be fully recommended for the needs of hop plants and brewery laboratories.
收起
摘要 :
A thin film platinum electrode-based electrolytic moisture sensor for the measurement of lower concentrations of moisture in gas streams with flow rates lesser than 5 ml/min was designed. The thin film electrode was fabricated wit...
展开
A thin film platinum electrode-based electrolytic moisture sensor for the measurement of lower concentrations of moisture in gas streams with flow rates lesser than 5 ml/min was designed. The thin film electrode was fabricated with pulsed laser ablation technique and screen printing. The PL-ablated electrode showed deterioration after 80 h of operation. The screen-printed thick film electrode sustained for more than 12 months. The response of the sensor was absolute and so the electrolytic and non-electrolytic currents were deduced. The sensor recovery time from either extreme dry or moist conditions was 70 s. The concentration of trace moisture in an argon cylinder was identified using the present design and the values were found to be 3.97 +- 0.07 ppm at cylinder pressure of 150 kg/cm~(2) and 37.41 +- 0.27 ppm at 30 kg/cm~(2). In addition to the sensitivity up to 1 ppm the present design could detect the sensor failure during operation.
收起
摘要 :
Tritium tracers are frequently used in biological assays during the drug discovery process because of their high specific activity and relative ease of synthesis. However, this high specific activity, along with other contributing...
展开
Tritium tracers are frequently used in biological assays during the drug discovery process because of their high specific activity and relative ease of synthesis. However, this high specific activity, along with other contributing factors, can lead to an increased rate of radiolytic decomposition. As a result, following long-term storage tritium tracers often require purification. Understanding the elements that cause radiolytic decomposition is extremely important to extend the storage life, and consequently reduce unnecessary inventory purifications. One of these elements is the presence of water in tritium tracers. Upon investigation, it was discovered that aside from the relatively common tritium/water exchange that could occur, residual water could also contribute significantly to the decomposition of tritium tracers. A near-infrared method was developed utilizing a portable device to measure the water content in tritium tracers rapidly and without sample destruction. This method proved to be quick, efficient, and achieved an error less than 5% compared to that of traditional Karl Fischer titration. Method validation was performed and good accuracy, linearity, limit of detection and quantitation were all established.
收起
摘要 :
The near-infrared spectroscopic (NIRS) method and multiple linear regression (MLR) method have been used for determination of the moisture content in tetracycline hydrochloride and oleandomycine phosphate in powdered forms.Chemome...
展开
The near-infrared spectroscopic (NIRS) method and multiple linear regression (MLR) method have been used for determination of the moisture content in tetracycline hydrochloride and oleandomycine phosphate in powdered forms.Chemometric calibration model has been developed using two absorption bands: at 5170 and 6850 cm-1.The determined mean moisture content in veterinary drugs Vetacyclinum pulvis (VP) and Polzomycine (P) varied in the range 2.52-3.54%.Detection limit and quantification limit were 0.31% and 0.92% for VP,and 0.58% and 1.75% for P,respectively.Intra-day and intermediate precisions of the proposed determination by the NIR method have been evaluated and RSD values of 0.99% and 1.89% for VP,and 0.85% and 1.13% for P were obtained.These numbers indicate reasonable repeatability and intermediate precision of NIR method.The accuracy of this method was compared to that of the reference Karl Fischer's method,and they were found consistent (99.2-100.1% and 99.1-99.8%,respectively),which proves applicability of the proposed NIR method in the routine determination of the moisture content in veterinary drugs.
收起
摘要 :
Time domain reflectometry (TDR) has been widely used by the scientific community as a reliable method to indirectly measure the volumetric water content (theta) of soils, and in most soils TDR can provide observations of theta at ...
展开
Time domain reflectometry (TDR) has been widely used by the scientific community as a reliable method to indirectly measure the volumetric water content (theta) of soils, and in most soils TDR can provide observations of theta at high temporal resolution with acceptable accuracy. This technique induces an electrical wave in waveguides inserted into the soil, estimates the soil bulk dielectric permittivity (epsilon) based on an interpretation of the reflected electromagnetic signal, and then relates epsilon with theta. In electrically conductive soils, the reflected signal can be highly attenuated by the effect of the soil's bulk electrical conductivity, resulting in very large errors in the estimation of theta; the traditional TDR methodology is thus subject to large errors and uncertainties. This work presents a simple and empirical waveform interpretation methodology based on variables less sensitive to the soil's electrical conductivity than those used in the traditional TDR methodology. This approach extends the applicability of TDR sensors with reliable and accurate measures of theta, making it possible to more accurately measure soil water contents in settings that have traditionally been difficult to observe, and without modifying the TDR sensors. (C) 2015 Elsevier B.V. All rights reserved.
收起
原文获取