Surface waves are a form of coherent noise that can obscure valuable reflection information in exploration records. It is sometimes difficult to eliminate these surface waves by traditional filtering approaches, such as an [Formula: see text] filter, without damaging the useful signals. As a partial remedy, we propose an interferometric method to predict and subtract surface waves in seismic data. The removal of surface waves by the proposed interferometric method consists of three steps: (1) remove most of the surface waves by a nonlinear local filter; (2) predict the residual surface waves by the interferometric method; (3) separate the residual surface waves from the result of step 2 by a nonlinear local filter, and remove the residual surface waves by a matched filter from the result of step 1. Field data tests for 2D and 3D data show that the method effectively suppresses surface waves and preserves the reflection information. Results suggest that the effectiveness of this method is sensitive to the parameter selection of the nonlinear local filter.

The limited recording aperture of a surface seismic experiment promotes artifacts in extrapolated wavefields. To mitigate these errors, we introduce least squares datuming (LSD). Numerical results with synthetic data show that LSD significantly reduces the artifacts in datuming wavefields recorded by narrow aperture arrays. Only inexpensive dot products of computed Green's functions with the data are required so this procedure is efficient for targetoriented reverse-time migration.

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We present a technique to eliminate the surface waves by an interferometry+nonlinear local filter (NLF). This technique consists of 3 steps: i) remove the surface waves by the NLF; ii) predict the residual surface waves and primaries by the interferometric method; iii) predict the surface waves by the NLF and remove the residual surface waves by a matched filter. Field data tests, for both 2D and 3D surveys, show that this technique effectively mitigates surface waves and preserves much of the reflection information.

The aim of this paper was to study the optimal extraction process of total triterpenes from loquat peel and pulp assisted by ultrasound. The effects of solid–liquid ratio, ethanol concentration, ultrasonic time, ultrasonic power, and ultrasonic temperature on the yield of triterpenoid acid in loquat were investigated by single-factor and response surface methodology. FRAP (Ferric ion reducing antioxidant power) method, ABTS (2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)) method, and DPPH (1,1-Diphenyl-2-picrylhydrazyl) method were used to determine the antioxidant capacity of peel and pulp at different stages. LC-MS (Liquid Chromatograph Mass Spectrometer) was used to qualitatively analyze different tissues of loquat. The optimal extraction conditions were as follows: ethanol concentration 71%, ultrasonic time 45 min, ultrasonic power 160 W, solid–liquid ratio 1:10, and ultrasonic temperature 30 °C. The total triterpenoid content of loquat peel was 13.92 ± 0.20 mg/g. The optimal extraction conditions were ethanol concentration 85%, ultrasonic time 51 min, ultrasonic power 160 W, solid–liquid ratio 1:8, and ultrasonic temperature 43 °C. The total triterpenoid content of loquat pulp was 11.69 ± 0.25 mg/g. The contents of triterpenes and antioxidant capacity in the peel and pulp of loquat at the three stages were the highest in the fruit ripening stage (S3). LC-MS analysis showed that most of the triterpenes belonged to ursolic acid derivatives and oleanolic acid derivatives, which laid the foundation for further utilization and development of loquat peel and pulp.