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As the existing belt tear detection method based on machine vision technology being used for images with complex background texture, it is easy to misjudge the defect areas with inconspicuous tear marks relative to the background texture as non-defects, and the detection results are noisy and difficult to identify. In order to solve the above problems, a belt tear detection method based on two-dimensional Gabor filter is proposed. The method uses Gabor filtering to process the belt images and obtain multiple Gabor filtered processing images. Through the Gabor optimization selection method, a new cost function is constructed based on the coefficient of variation, and the optimal filter channel is selected to highlight the texture characteristics of the tear area. The Sobel operator is used to extract the texture characteristics of the tear area in the horizontal and vertical directions respectively so as to obtain the gradient images of the two directions. The self-propagation normalization operation is applied on the obtained gradient images to enhance the texture information, and the pixel-weighted average method is used to fuse the two images. The obtained fused images are segmented by adaptive threshold binarization method, and morphological technology is used to perform belt tear detection on the images to be detected. The detection results show that the improved Gabor optimization selection method has a lower miss detection rate than the Gabor optimization selection method and the Sobel operator-based longitudinal tear detection method. The method can detect all defects in the belt defect images with complex background texture. The detection results are clear and the contour characteristics of the tear area are preserved relatively well.

Abstract Millimetre wave (mmWave) has great potential in vehicle‐to‐vehicle (V2V) communication to provide wide bandwidth and low latency. However, the biggest challenge for the use of mmWave is the high propagation path loss and susceptibility to blockage among vehicles, especially in urban streets. Vehicle shadow fading is quite common in the actual V2V communication. The non‐line‐of‐sight scenarios are considered and the impacts of blocking vehicles on the characteristics of the V2V wireless channels are studied. The measurements are conducted for two scenarios. For the first scenario, a blocking truck is placed between transmitting and receiving cars. For the second scenario, a car is added as a reflector beside the truck. Based on the measurement results, a path loss model for the V2V communication is developed. In order to further verify the effects of building scattering, a simulation is setup and the results are consistent with the measured results.

With the aid of applying decomposed loads,a method is suggested to construct primary structure and obtain the primary bending stress for the tubesheet of fixed tubesheet heat exchanger. The favorable redundant rotation constraint of the cylinder to the tubesheet can be remained in the primary structure. Taking a methyl alcohol synthetic reactor as example,the mentioned method is used in the FEA to solve the problem without primary structure analysis. It is founded that the allowable load yielded by the mentioned method is comparative to that by direct limit load analysis,which indicates the feasibility of the mentioned method. It should be noted that the conode simplication of the tube and the tube hole are generally non-conservative. If the stress intensity evaluation line is located on the tube hole,a suitable stress intensity enlargement factor should be employed.

Coinage metal nanoclusters usually show bright emission, which is useful for obtaining circularly polarized luminescence (CPL) after modifying with chiral organic ligands. However, it remains challenging to understand the chiral transfer and amplification mechanisms and achieve CPL inversion without changing the absolute configuration of the chiral ligands. Here, we present four pairs of six-core silver nanoclusters protected by the chiral thiazinthione- and oxazinthione-based ligands, showing S⋯S interaction-enhanced luminescence quantum yield (QY) and supramolecular chirality inversion induced by the peripheral methyl and phenyl groups in both ground and excited states. [ABSTRACT FROM AUTHOR]

The abuse and irrational use of tetracyclines (TCs) in human medicine and animal husbandry has become a serious concern, affecting the ecological environment and human health. The aim of this study was to develop a sensitive and selective method using fully automatic solid-phase extraction coupled with ultra-performance liquid chromatography–tandem mass spectrometry for the determination of twelve TCs in water. Four isotope-labeled internal standards for TCs were used to correct matrix effects. Several parameters affecting extraction efficiency were systematically optimized, and the optimum experimental conditions found were 1.0 L water sample with 0.5 g/L Na2EDTA (pH 3.0) extracted and enriched by CNW HLB cartridge and eluted by 4 mL of acetone:methanol (v/v, 1:1). The enrichment factors were up to 798−1059 but only requiring about 60 min per six samples. Under the optimized conditions, the linearity of the method ranged from 0.2 to 100 μg/L for 12 TCs, the detection limits were as low as 0.01−0.15 ng/L, and the recoveries were in the range of 70%–118%, with relative standard deviations less than 15%. The developed method can be successfully utilized for the determination of 12 TCs in pure water, tap water, river water, and mariculture seawater. In summary, three and six TCs were detected in river water and mariculture seawater, respectively, with total concentrations of 0.074–0.520 ng/L (mean 0.248 ng/L) and 0.792–58.369 ng/L (12.629 ng/L), respectively. Tetracycline (TC) and oxytetracycline (OTC) were the dominant TCs in river water, while doxytetracycline (DXC) and OTC were dominant in mariculture seawater. [ABSTRACT FROM AUTHOR]

Perovskite solar cells exhibit immense potential for practical use due to their high power conversion efficiency (PCE) and low fabrication cost. However, UV light is an unavoidable threat to long-term stability as it promotes undesirable chemical reactions within the cells. Herein, we introduce N-acetyl-5-methoxy-tryptamine (melatonin), a natural product with antioxidative properties, for the UV protection of perovskite, attributable to its ability to absorb UV light and scavenge radicals. Additionally, the defects in perovskite are effectively passivated due to interactions between perovskite and melatonin. Consequently, the photovoltaic performance is enhanced due to reduced defect density in the perovskite and the improved charge transport from the perovskite layer to the charge transport layer. Furthermore, the devices fabricated using this strategy demonstrate an outstanding storage stability, retaining 85% of the initial PCE after 2225 hours of storage in air (unencapsulated, 20–30 °C, RH ∼30%), and UV endurance, sustaining 70.86% of the original PCE after UV illumination for 617 hours in air. [ABSTRACT FROM AUTHOR]