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A BIM technology-based underwater structure damage identification and management method

Li Xiaofei, Su Rongrong, Cheng Peng, Sun Heming, Meng Qinghang, Song Taiyi, Wei Mengpu, Zhang Chen

Bulletin of the Polish Academy of Sciences. Technical Sciences

2023

Vol. 71, nr 2

art. no. e144602

With the continuous development of bridge technology, the condition assessment of large bridges has gradually attracted attention. Structural Health Monitoring (SHM) technology provides valuable information about a structure's existing health, keeping it safe and uninterrupted use under various operating conditions by mitigating risks and hazards on time. At the same time, the problem of bridge underwater structure disease is becoming more obvious, affecting the safe operation of the bridge structure. It is necessary to test the bridge’s underwater structure. This paper develops a bridge underwater structure health monitoring system by combining building information modeling (BIM) and an underwater structure damage algorithm. This paper is verified by multiple image recognition networks, and compared with the advantages of different networks, the YOLOV4 network is used as the main body to improve, and a lightweight convolutional neural network (Lite-yolov4) is built. At the same time, the accuracy of disease identification and the performance of each network are tested in various experimental environments, and the reliability of the underwater structure detection link is verified.

Multiscale water drop contact angles at selected silica surfaces

Zhang Chen, Wang Xuming, Li Lixia, Jin Jiaqi, Polson Randy, Miller Jan D.

Physicochemical Problems of Mineral Processing

2022

Vol. 58, iss. 5

art. no. 152154

In this study, multiscale advancing contact angles for glycerol/water drops at silica surfaces are reported for millidrops, submicron-drops, and nanodrops. Selected silica surfaces were muscovite, silicon, and talc. The contact angles for millidrops (1–2 mm) were determined by the traditional sessile drop technique. For submicron-drops (0.1–1.0 μm), a hollow tip Atomic Force Microscope (AFM) procedure was used. The contact angles for nanodrops (~7 nm) were examined from Molecular Dynamics (MD) simulation. The results were compared to evaluate the effect of drop size on the contact angle. In the case of the hydrophobic talc surface, the 75° advancing contact angle did not vary significantly with drop size. For the hydrophilic muscovite surface, the water drop wet the surface and an advancing contact angle of about 10° was found for the millidrops and submicron-drops. However, for the MD simulated nanodrops, attachment and spreading of the ~7 nm drop created a 2D film of molecular dimensions, the contact angle of which was difficult to define and varied from 0° to 17°. Perhaps of equal interest from the MD simulation results was that the spreading of the glycerol/water nanodrop at the muscovite surface resulted in crystallographic directional transport of water molecules to the extremities of the 2D film. Such separation and segregation left the center of the film with an increased concentration of glycerol. Based on these results, the line tension, which has been found in other investigations to account for contact angle decrease with a decrease in drop size, does not seem to be a significant factor in this study.

Comparison of the depression effect of two thiol depressants on the separation of specularite and aegirite

Li Mingyang, Zhang Chen, Gao Xiangpeng, Xie Xian, Tong Xiong

Physicochemical Problems of Mineral Processing

2022

Vol. 58, iss. 6

art. no. 152164

In this work, two thiol-type reagents, thioglycolic acid (TGA) and mercaptopropionic acid (MPA), were firstly exploited and compared as aegirite depressants with sodium oleate (NaOl) as the collector to separate specularite from aegirite by flotation. The adsorption performances and mechanisms of TGA and MPA on aegirite surface were investigated via flotation experiments, Zeta potential tests, adsorption measurements, contact angle dimensions, and surface characterizations. The results of flotation indicated that TGA and MPA exhibited a considerable depression impact on the flotation of aegirite but little effect on specularite. TGA depicted more excellent depression performance than MPA, which was confirmed by HLB calculation. The results demonstrated that TGA and MPA favorably adsorbed on aegirite surface instead of specularite, hindering the subsequent adsorption of NaOl on specularite and resulting in the surface being hydrophilic. XPS results revealed that TGA and MPA were significantly adsorbed on the surface of aegirite through an interaction between the carboxyl and thiol groups of the depressants and the Si and Fe on the surface of aegirite.