Train axlebox bearings are subject to harsh service conditions, and the difficulty of diagnosing compound faults has brought greater challenges to the maintenance of high-quality train performance. In this paper, based on the traditional symplectic geometry mode decomposition (SGMD) algorithm, a maximum spectral coherence signal reconstruction algorithm is proposed to extract the intrinsic connection between the SGMD components with the help of the frequency domain coherence idea and reconstruct the key signal components so as to effectively improve the extraction of composite fault features of axlebox bearings under different speed conditions. Firstly, based on the traditional SGMD algorithm, the vibration signal of the axle box is decomposed to extract its symplectic geometry components (SGCs).
View Article and Find Full Text PDFEnviron Sci Pollut Res Int
August 2023
Environ Sci Pollut Res Int
July 2023
With 2008-2020 China's provincial panel data as the research object, we use the entropy weight method to compute green finance and pollution, and we empirically study the scope of the spillover effects and threshold impacts of green finance on environmental pollution using the spatial Durbin model and threshold regression model. The findings are as follows: first, under different spatial weight matrices, green finance has a spatial spillover effect on pollution. And the effect boundary is approximately 500 km.
View Article and Find Full Text PDFIn the signal processing of real subway vehicles, impacts between wheelsets and rail joint gaps have significant negative effects on the spectrum. This introduces great difficulties for the fault diagnosis of gearboxes. To solve this problem, this paper proposes an adaptive time-domain signal segmentation method that envelopes the original signal using a cubic spline interpolation.
View Article and Find Full Text PDFMetabolism, transformation and dynamic changes of DNJ, 2-O-α-D-Gal-DNJ, fagomine, isofagomine and 4-O-β-d-Glc-fagomine from mulberry leaves in silkworms at different instars were observed. UPLC-Q/TOF-MS and UPLC-TQ/MS methods were adopted for qualitative and quantitative analysis respectively. Three species mulberry leaves were used to feed the silkworm as controls.
View Article and Find Full Text PDFBMC Complement Altern Med
November 2016
Background: Tripterygium wilfordii Radix, a well-known traditional medicine in china which is used for treatment of inflammation, pain, tumor and immune regulation for centuries in china, accompany with the serious toxic side effects. This study was carried out for simultaneously analyzing the four main components (triptolide, triptophenolide, demethylzeylasteral and celastrol) in Tripterygium wilfordii Radix under different drying processes, which was important for reducing the toxicity and quality control of Tripterygium wilfordii Radix in future.
Methods: The terpenes were extracted by using ultrasonic method with ethyl acetate from root or cortex of Tripterygium wilfordii Radix, and the sensitive and rapid HPLC-PDA method was developed for simultaneous quantification of triptolide, triptophenolide, demethylzeylasteral and celastrol in root and cortex of Tripterygium wilfordii Radix for evaluation of the impacts by different drying processes.
Zhongguo Zhong Yao Za Zhi
December 2014
To investigate the optimum harvesting time and utilization of mulberry leaves during different growth periods based on the content of alkaloids and flavonoids, 88 samples of 11 species of mulberry leaves were collected and analyzed. UPLC-TQ/MS method was applied and the results showed that the ingredients of alkaloids and flavonoids in mulberry leaves are quite different in different growth periods and different species. There was a sharp decline of the average content of alkaloids in all samples from October, while the content of flavonoids dropped either from October but with less volatile.
View Article and Find Full Text PDFObjective: To find out dynamic changes of flavonoids and alkaloids in Morus alba leaves by analyzing influence of different drying method and drying degrees, in order to provide evidence for quality evaluation of Morus alba leaves.
Methods: Different drying methods, programmed temperature methods and constant temperature methods were adopted to dry Morus alba leaves samples respectively. Contents of flavonoids and alkaloids were analyzed by HPLC-PDA and LC-TQ/MS respectively.
An ultra high performance liquid chromatography coupled with a triple quadrupole mass detection and electrospray ionization mass spectrometry method has been established for the simultaneous determination of the 14 nucleosides and nucleobases, 24 amino acids and two main alkaloids in mulberry leaf. In this method, a complicated mobile phase, the flow rate of which was 0.4 mL/min, was applied to the gradient elution, which provided a satisfied separation of the 40 compounds.
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