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Removal of Fouling from Steel Plate Surfaces Based on Multi-Frequency Eco-Friendly Ultrasonic Guided Wave Technology

Huang Mingkun, Jin Shuo, Nie Gaoqian, Wang Xiaopeng, Zhang Quanpeng, An Yang, Qu Zhigang, Yin Wuliang

Archives of Acoustics

2023

Vol. 48, No. 4

593--601

Fouling is inevitable on the surfaces of industrial equipment, especially on heat-exchanging surfaces in contact with fluids, which causes water pollution and destroys the ecological environment. In this paper, a novel fouling-removal methodology for plate structure based on cavitation by multi-frequency ultrasonic guided waves is proposed, which can remove fouling on stainless steel plates. A numerical simulation method has been developed to study the acoustic pressure distribution on a steel plate. According to the simulation results, the distribution of sound pressure on the plate under triple-frequency excitation is denser and more prone to cavitation than in single-frequency cases and dual-frequency cases, which improves fouling removal rate. The stainless steel plate is immersed in water for the descaling experiment, and the results show that the fouling removal rates of three water-loaded stainless steel plates under different single-frequency excitation seem unsatisfactory. However, the multi-frequency excitation improves the descaling performance and the removal rate of fouling reaches 80%. This new method can be applied to the surface descaling of large equipment plates, which is of great significance for purifying water quality and protecting the ecological environment.

Temporal stability of soil apparent electrical conductivity (ECa) in managed podzols

Badewa Emmanuel, Unc Adrian, Cheema Mumtaz, Galagedara Lakshman

Acta Geophysica

2019

Vol. 67, no. 4

1107--1118

The spatial variability in soil physical and hydraulic properties for a managed podzol was assessed using soil apparent electrical conductivity (ECa). Two EMI sensors, the multi-coil (MC) and multi-frequency (MF), were adopted for measurement of ECa on a silage- corn experimental plot in western Newfoundland, Canada. Results demonstrated a significant relationship between the ECa mean relative differences (MRD) and the soil moisture content MRD (R2=0.33 to 0.70) for both MC and MF sensors. The difference in depth sensitivity between MC and MF sensors accounted for the variation (0.015 to 0.09) in ECa standard deviation of the relative differences. A significant linear relationship was found between the ECa MRD and sand (R2=0.35 and 0.53) or silt (R2=0.43), but not with clay (R2=0.06 and 0.16). The spatial variability of the ECa-based predictions (CV=3.26 to 27.61) of soil properties was lower than the measured values (CV=5.56 to 41.77). These results inferred that the temporal stability of ECa might be a suitable proxy to understand the spatial variability of soil physical and hydraulic properties in agricultural podzols.

Research on the dot-by-dot imaging algorithm for multi-beam SAS with multi-frequency in azimuth

Zhou T., Li H., Xu J., Xu C.

Przegląd Elektrotechniczny

2013

R. 89, nr 3b

188--192

In multi-beam synthetic aperture sonar (SAS), the smaller the transmit sensor array’s physics aperture is, the larger its synthetic aperture length is, and then the better its along-track resolution will be. But when the physics aperture is small, the mapping speed should be limited to avoid the azimuth ambiguity. In order to overcome this problem, a scheme of multi-beam SAS with multi-frequency in azimuth is proposed in this paper based on the sensor array configuration and basic principle of multi-beam SAS. A correlated math model is presented and the dot-by-dot imaging algorithm is simulated according to the new scheme. Compared with the primary multi-beam SAS scheme proposed before, the new scheme can improve the along-track resolution and increase the mapping speed. Computer simulation results are given to test the correctness and efficiency of the new scheme.

W artykule przedstawiono nową strukturę wielowiązkowego sensora SAS, pozwalającą na eliminację problemów związanych z dwuznacznością azymutu. Proponowane rozwiązanie bazuje na podstawowych zasadach działania SAS oraz odpowiedniej konfiguracji tablicy czujników. Zbudowano także model matematyczny oraz opracowano algorytm pozwalający na obrazowanie działania punkt po punkcie. Dokonano weryfikacji symulacyjnej proponowanej struktury.