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Noise pollution is the most serious environmental pollution, which seriously affects people's normal life and physical and mental health, as well as normal production work. Therefore, noise control is necessary, but before noise control, the first thing to do is to identify the location of the noise source, and the noise control work is meaningless when the noise cannot be identified. Flat plate structures are a fundamental part of complex ship structures, and their vibration, noise, and their interrelationships when excited by the outside world are receiving increasing attention. The core of the research in this paper is the identification of the sound source of the vibrating plate. A method combining phase conjugation with interior boundary element method is developed for the identification of the pressure and normal velocity distribution of a vibrating plate. An interior problem is formed by enclosing the phase conjugation array plane and the plate surface. The pressures at the array elements are phase-conjugated as the specified pressure boundary condition. The impedance relationship between the surface pressure and the surface normal velocity of the plate is utilized as a specified impedance boundary condition. The interior boundary element method is applied to solve the interior problem. The identification of the surface pressure and normal velocity distribution is studied numerically. The numerical results show that with the array located in the near field the proposed method achieves subwavelength focusing to identify the surface pressure and normal velocity distribution and clearly shows the response shapes. [ABSTRACT FROM AUTHOR]

Drip irrigation has a close relationship with the growth and development of maize grains and yield formation in semiarid areas. To explore the response mechanism of grain yield formation to drip irrigation quotas, a 2-year pond planting experiment was conducted under controlled conditions, by using two maize varieties with differences in drought resistance as experimental materials. Six treatments were set up, including CK1 (drought-resistant variety, 500 mm), T1 (drought-resistant variety, 350 mm), T2 (drought-resistant variety, 200 mm), CK2 (drought-sensitive variety, 500 mm), T3 (drought-sensitive variety, 350 mm), and T4 (drought-sensitive variety, 200 mm). The changes in maize grain filling characteristics, related hormones, enzyme activity related to starch synthesis, sugars and amino acids contents, and yield were analysed. The results showed that 100-grain weight at different filling times, filling rate, average filling rate, auxin, cytokinin, acid sucrose invertase, sucrose synthase, starch synthase, and adenosine diphosphate glucose pyro phosphorylase activities in maize grains decreased and the abscisic acid content and content of various amino acids and sugars in grains increased with the decrease in drip irrigation quota. The percentage of changes in drought-sensitive maize varieties was relatively high. The maize yield decreased with the decrease in drip irrigation quota. In summary, there was no significant difference in grain filling characteristics, hormone content, starch synthesis enzyme activity, and yield between maize treated with T1 (drought-resistant variety, 350 mm) and the control treatment. This effectively maintained grain growth and yield formation, achieving the goal of water saving and stable yields. [ABSTRACT FROM AUTHOR]

Lavas from back‐arc basins are generally diverse, and their geochemical compositions indicate that they received variable contributions from subduction components during petrogenesis. Obtaining comprehensive geochemistry characteristics for the entire back‐arc basin are helpful in gaining a better understanding of the complexities of back‐arc evolution. In this study, we systematically reviewed the major and trace element compositions of Lau Basin lavas. This data set covered all of the major tectonic units of the basin, for example, the Eastern Lau spreading center (ELSC), the Valu Fa ridge (VFR), the Central Lau spreading center (CLSC), the Northwestern Lau spreading center (NWLSC), the Northeastern Lau spreading center (NELSC), the Mangatolu Triple Junction (MTJ), and the Fonualei Spreading Center (FSC). The lava types from these locations are diverse, including tholeiitic basalts, alkali basalts, basaltic andesites, andesites, dacites, and rhyolites. In addition, the NELSC and FSC contain boninites. In this study, the geochemical compositions of these diverse rock types are used to investigate the spreading dynamics of the Lau Basin back‐arc. We conclude that (a) the subduction components mainly include hydrous fluids released from the subducted slab, and hydrous melt directly from the melting subducted sediment, and the influence of the subducted components on the mantle wedge and the petrogenesis of the central and southern Lau Basin lavas decreases with increasing distance from the Tonga Trench; (b) during the propagation and spreading of the Samoan mantle into the Lau Basin, lavas from the NELSC, NWLSC, MTJ, and even from the northern part of the FSC may receive variable degrees of influence from the Samoan plume; and (c) the migration of Indian MORB‐like mantle southwards into the Pacific mantle is consistent with the opening of the Lau Basin. With the gradual migration of Indian mantle into the Lau Basin, a series of spreading centers were formed, for example, in order, the NWLSC, CLSC, ELSC, and the propagating VFR. [ABSTRACT FROM AUTHOR]