When the MLD method is used to determine the main chemical composition in the cement, it is assumed that the sum of the measured chemical composition is 100%. When the trace amount of heavy metal oxide is present in the cement sample without measuring, a positive error will be caused for main chemical composition results. On the other hand, according to the national standards GB/T 30760-2014 "technical specification for coprocessing of solid waste in cement kiln", also need to determine the heavy metals in cement. In this work, vanadium pentoxide, chromium oxide, copper oxide, zinc oxide, strontium oxide and barium oxide were measured by using melt beads for the determination of the main chemical components in cement. The calibration sample was calibrated using the standard addition – fusion method, using the theoretical MLD coefficient to calculate the standard dilution ratio. The method has been applied to the determination of heavy metal oxides in cement samples and achieved good results.
In order to overcome the defect of traditional engine condition monitoring only depending on single parameter, this paper establishes the five-level condition monitoring alert system with fuzzy neural network (FNN) which is good at settling uncertain and complicated problems. Firstly, optimal monitoring parameters are selected from three aspects of ferrography, vibration and performance parameters. With sufficient historical data, limit values of parameters and reliable five-level condition monitoring standards are maintained and established by statistical analysis. Then fuzzy membership functions are applied to transform practical data into fuzzy data. Finally the structure of neural network is designed and trained by sample data. The model is tested with original data and proved to be more effective and reliable to engine condition monitoring.
When an X-ray photon which is generated by the sample enters into the detector, pulses can be produced and recorded. The detector is unable to respond to another photon that enters at the same time when a photon is being detected. The time that the detector takes to respond to a photon is regarded as dead time. For the x-ray fluorescence detector, the recorded count is less than the real count impulse due to dead time. Hence, to correct x-ray intensity of samples whose element content is vastly different, determination of dead time is necessary. In this paper, a new and complete way to determine dead time is proposed, which can be summarized as “intensity pair method”. Three “intensity pairs” were used for determining dead time, which were “intensity pair” of collimators (S2 and S4), “intensity pair” of spectral lines (Kα and Kβ) and “intensity pair” of beads with different flux-sample ratio (higher SH and lower SL analyte content in the beads). It comes to a conclusion that dead time obtained from “intensity pair” of beads is the most practical method for correcting X-ray fluorescence intensity. As for routine analysis, the dead time of proportional counter can be accurate to 1×10-9s, which can make intensity correction error less than 0.1%.
In this paper a novel approach is presented for determination of the main components in MgO-Cr refractory material. With the approach, the intensity conversion of fused sample at different dilution ratios can be obtained by establishing the correlation between elements’ intensity and dilution ratio. MgO-Cr refractory material is fused hardly and the dilution ratio requires more than 20 in XRF analysis. Nevertheless, high dilution can reduce the detection sensitivity of low content elements. Using the technology of intensity conversion at different dilution ratio in this paper, a calibration curve was obtained with different dilution ratios. In this method, we obtained a calibration curve successfully and got the satisfactory results for MgO-Cr refractory which was fused well. The new method suggests consistent accuracy and precision with standard method, and it can also simplify the preparation process of samples. The approach shows high sensitivity, good accuracy and precision, meanwhile, it reduces the technical difficulty and labor intensity greatly in analysis method.
The contents of each element in the melting glass samples of zircon-refractory material were measured by X-ray fluorescence spectrometry. The samples were melted completely with uniform intensity. Then the incident ray absorption coefficient and the MLD coefficient of the solvents and samples were extracted by using the method of equivalent wavelength. Finally the chemical composition of zircon-refractory material was determined by MLD coefficient and normalization calculation method. The results are consistent with those obtained with the national standard method and the absolute value of error is less than 0.1%. The precision is comparative with the counting error of XRF analysis and the absolute value of the standard deviation is less than 0.05%, being much higher than national standard method. At the same time, this method is simple, easy to be operated.
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