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Aiming at the problem that it is difficult to effectively characterize the operation status of hydropower units with a single vibration signal feature under the influence of multiple factors such as water–machine–electricity coupling, a multidimensional fusion feature extraction method for hydroelectric units based on time–frequency analysis and unsupervised learning models is proposed. Firstly, the typical time–domain and frequency–domain characteristics of vibration signals are calculated through amplitude domain analysis and Fourier transform. Secondly, the time–frequency characteristics of vibration signals are obtained by combining the complementary ensemble empirical mode decomposition and energy moment calculation methods to supplement the traditional time–domain and frequency–domain characteristics, which have difficulty in comprehensively reflecting the correlation between nonlinear non–stationary signals and the state of the unit. Finally, in order to overcome the limitations of shallow feature extraction relying on artificial experience, a Stacked Denoising Autoencoder is used to adaptively mine the deep features of vibration signals, and the extracted features are fused to construct a multidimensional feature vector of vibration signals. The proposed multidimensional information fusion feature extraction method is verified to realize the multidimensional complementarity of feature attributes, which helps to accurately distinguish equipment state types and provides the foundation for subsequent state identification and trend prediction. [ABSTRACT FROM AUTHOR]

Monitoring methods for beta-lactam (β-lactam) antibiotics, especially for ampicillin (AMP), with simple operation and sensitivity for realtime applications are highly required. To address this need, antioxidant carbon dots (E-CDs) with excellent fluorescence properties were synthesized using citric acid and ethylenediamine as raw materials. With a quantum yield of 81.97%, E-CDs exhibited a specific and sensitive response to ˙OH. The quenched fluorescence of E-CDs by the formed ˙OH could be restored through a competition reaction with AMP. Leveraging the signal-quenching strategy of E-CDs, H2O2, and Fe2+, a fluorescence signal-on strategy was developed using AMP as the fluorescence recovery agent for the sensitive detection of AMP. The mechanism of the quenching of E-CDs by ˙OH was attributed to the damaging effect of ˙OH on E-CDs. Under optimal conditions, the detection limit of this method for AMP was determined to be 0.38 μg mL−1. This method was successful in drug quality control and the spiked detection of AMP in lake water, milk, and sea cucumber, presenting a viable option for convenient and rapid antibiotic monitoring methods. [ABSTRACT FROM AUTHOR]

BackgroundIn the long-term uninterrupted work of the real-time on-line monitoring system of water radioactivity, the spectrum drift, line broadening and shift of peak position are caused by the temperature change of the detector and various electronic components and the aging of components, which leads to the difficulty of spectral line analysis and the error of analytical results.PurposeThis study aims to develop a calibration device for real-time on-line monitoring system of water radioactivity based on cerium bromide detector.MethodsThe device was designed to consists of 137Cs standard source (exemption source), lead block, lead chamber with calibration hole and linear motor. The optimum opening radius of the calibration hole and the optimum thickness of the lead block were obtained by Monte Carlo simulation. The standard 137Cs source was used as the standard reference peak, and the calibration of peak position and peak area, the peak position drift and peak area of 137Cs full-energy peak was analyzed by software with real-time gain calculation and parameters adjustment. Finally, the device was applied to the field application verification.Results & ConclusionsResults of Monte Carlo simulation indicate that the optimum radius of the calibration hole is 2.2 cm and the optimum thickness of the lead block is 5 cm. The verification results shows that the device can limit the change of peak position and peak area to ±1% and ±5%, respectively.

BackgroundWith the vigorous development of the nuclear industry and the widespread application of nuclear technology, the radioactivity of inland water has become one of the key objects of radiation environmental monitoring. CeBr3 scintillation detector is one of candidates for water on-line radioactivity measurement system, but its detection efficiency is not high enough.PurposeThis study aims to improve the detection efficiency of the water on-line radioactivity measurement system by optimization of array CeBr3 detector layout, and reduce the detection limit.MethodsFirstly, calculate the optimal number of detectors in the system according to the minimum detectable activity concentration formula was calculated. Then, the Monte Carlo method was used to simulate the number and arrangement of ⌀45 mm×50 mm CeBr3 array detectors to obtain optimized arrangement of detectors. Finally, the water on-line radioactivity measurement system with optimized layout of array CeBr3 detectors was applied to continuous monitoring of the water bodIES of a river basin in Sichuan province.ResultsThe simulation results show that the three CeBr3 detectors placed in triangular arrangement and close to each other achieve a minimum detectable activity concentration of 0.1 Bq·L-1 for 137Cs radioactive source, meeting the design standard of system detection limit.ConclusionsThe monitoring results show that the system can effectively monitor the variations of radioactivity concentration of total α/β and 238U, 232Th and 40K in the water.

One-pot synthesis of a novel mesoporous hydroxyl oxidize iron functional Na-zirconium phosphate (FeOOH-NaZrH(PO4)2·H2O) composites was firstly characterized and investigated its Co(II) adsorption from aqueous solution. Compared to NaZrH(PO4)2·H2O (65.7 mg⋅g−1), the maximum Co(II) adsorption capacity of FeOOH-NaZrH(PO4)2·H2O was improved to be 95.1 mg⋅g−1. BET verified the mesoporous structures of FeOOH-NaZrH(PO4)2·H2O with a larger pore volume than NaZrH(PO4)2·H2O. High pH values, initial Co(II) concentration, and temperature benefited the Co(II) adsorption. Kinetics, isotherms, and thermodynamics indicated an endothermic, spontaneous chemisorption process. FeOOH-NaZrH(PO4)2·H2O has a better Co(II) adsorption selectivity than that of NaZrH(PO4)2·H2O. In particular, FeOOH-NaZrH(PO4)2·H2O exhibited an outstanding reusability after ten cycles of tests. The main possible mechanism for adsorbents uptake Co(II) involved in ion exchange, electrostatic interaction, and -OH, Zr-O bond coordination based on FTIR and XPS analysis. This work presents a feasible strategy to prepare novel modified zirconium phosphate composites for extracting Co(II) from solutions and providing a new insight into the understanding of Co(II) adsorption in the real nuclear Co(II)-containing wastewater. [ABSTRACT FROM AUTHOR]

A photonic integrated interference imaging system (PIIIS) is a computational imager based on Michelson interference and photonic integrated circuits (PICs). In this paper, a PIIIS based on a compact sampling lenslet array that can sample the zero spatial frequency through a single lenslet, densely sample the frequency in the azimuth direction through the configuration of a hierarchical multistage lenslet array, and continuously sample the frequency in the radial direction through a Langford sequence is proposed. We introduce the design process of the compact sampling lenslet array in detail and simulate the imaging of the system. The simulation results demonstrate that the lenslet array can effectively improve the imaging quality of a PIIIS. In addition, we design a silicon PIC and a silicon nitride transition PIC that match the compact sampling lenslet array and simulate the imaging of the system under the influence of the on-chip optical loss of PICs (the average interference baseline loss is 15.4 dB at 1550 nm). The results show that on-chip optical loss mainly affects the brightness and contrast of the reconstructed image but has little effect on the structure. [ABSTRACT FROM AUTHOR]