Determination method of the structure size interval of dynamic similar models for predicting vibration characteristics of the isotropic sandwich plates

A method is studied for determining the structure size interval of dynamic similar models of the isotropic sandwich plates. Firstly, a comparison between the two theories of plates, the Resineer theory and the Hoff theory, is conducted, including their governing equations and the ANSYS analytic solutions of frequency. The Resineer theory is chosen as the basic theory of this paper finally. Secondly, the scaling laws between the model and prototype of isotropic sandwich plate are established by combining the dimensional analysis and governing analysis. Both complete and incomplete geometric similarity conditions are discussed. Thirdly, the determination method of the structure size interval of the models is proposed. The nature vibration mode keeps the same and the nature frequency and harmonic response keep in proportion with the prototype of the sandwich plate. At last, the flow step of the intervals determination method is given

Synthesis of BiOI-TiO 2

This study was conducted to synthesize a series of nanosized BiOI-TiO2 catalysts to photodegrade Bisphenol A solution. The BiOI-TiO2 nanoparticles were synthesized in the reverse microemulsions, consisting of cyclohexane, Triton X-100, n-hexanol, and aqueous salt solutions. The synthesized particles were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface analyzer, Fourier transform-infrared spectroscopy (FT-IR), ultraviolet-visible light (UV-Vis) absorption spectra and transmission electron microscope (TEM). The photodegradation of Bisphenol A (BPA) in aqueous suspension under visible light irradiation was investigated to explore the feasibility of using the photocatalytic method to treat BPA wastewater. The effects of different molar ratios of BiOI to TiO2 on the photocatalytic activity were discussed. The experimental results revealed that the photocatalytic effect of the BiOI-TiO2 particles was superior to the commercial P25 TiO2. The BPA degradation could be approached by a pseudo-first-order rate expression. The observed reaction rate constant (kobs) was related to nanoparticles dosage and initial solution pH

CTAB-Assisted Hydrothermal Synthesis of Bi 2

Pyrochlore-type Bi2Sn2O7 (BSO) nanoparticles have been prepared by a hydrothermal method assisted with a cationic surfactant cetyltrimethylammonium bromide (CTAB). These BSO products were characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and UV-visible diffuse reflectance spectroscopy (DRS). The results indicated that CTAB alters the surface parameters and the morphology and enhances the photoinduced charge separation rate of BSO. The photocatalytic degradation test using rhodamine B as a model pollutant showed that the photocatalytic activity of the BSO assisted with CTAB was two times that of the reference BSO. Close investigation revealed that the size, the band gap, the structure, and the existence of impurity level played an important role in the photocatalytic activities

The Tribo-Corrosion Behavior of Monel 400 Alloy in Marine Environment at Varied Rotational Velocities

Monel 400 alloy is widely employed in marine engineering equipment due to its excellent corrosion resistance, high strength and toughness. In this paper, the tribo-corrosion behavior of Monel 400 alloy in seawater under different rotational velocities was investigated by a pin-disk tribometer with an integrated electrochemical cell. The results revealed that the material loss rate and friction coefficient of the Monel 400 alloy, after tribo-corrosion and mechanical wear tests, increased with increasing rotational velocity. Under mechanical-wear conditions, the material loss rate increased with the sliding distance extension at higher velocities, and then more serious crack nucleation and propagation occurred at the subsurface. Under tribo-corrosion conditions, when the rotational velocities increased from 0.125 m/s to 0.5 m/s, the thickness of the corrosion product’s layer was reduced from 50 nm to 30 nm; that is, the lubrication of the corrosion product became worse. As a result, the material-loss rate and friction coefficient increased significantly at the velocity of 0.5 m/s. Importantly, the antagonistic effect, rather than the synergistic effect, between corrosion and mechanical wear, has been verified for the tribo-corrosion of Monel 400 alloy in seawater, and the mechanism was analyzed

Adaptive weighted real‐time compressive tracking

Many tracking methods often suffer from the drift problems caused by appearance change. Therefore developing a robust online tracker is still a challenging test. Recently, a simple yet effective and efficient tracking algorithm has been proposed by compressive tracking (CT) paradigm to alleviate the drift to some degree. The CT tracker introduced an appearance model based on features extracted from the multi‐scale image feature space in the compressed domain. However, the CT tracker may detect the positive sample that is less important because it does not discriminatively consider the sample importance in its learning procedure. In this study, the authors integrate the sample importance into the CT tracker online learning procedure. They also add an efficient feature select method which can choose the most discriminative power weak classifier and employ the co‐training criterion into CT tracker to improve the tracking performance. Experiments show that the proposed tracker demonstrates the superior performance in robustness and efficiency than other state‐of‐the‐art trackers

Recommending Advanced Deep Learning Models for Efficient Insect Pest Detection

Insect pest management is one of the main ways to improve the crop yield and quality in agriculture and it can accurately and timely detect insect pests, which is of great significance to agricultural production. In the past, most insect pest detection tasks relied on the experience of agricutural experts, which is time-consuming, laborious and subjective. In rencent years, various intelligent methods have emerged for detection. This paper employs three frontier Deep Convolutional Neural Network (DCNN) models—Faster-RCNN, Mask-RCNN and Yolov5, for efficient insect pest detection. In addition, we made two coco datasets by ourselves on the basis of Baidu AI insect detection dataset and IP102 dataset, and compared these three frontier deep learning models on the two coco datasets. In terms of Baidu AI insect detection dataset whose background is simple, the experimental results strongly recommend Yolov5 for the insect pest detection, because its accuracy reaches above 99% while Faster-RCNN’s and Mask-RCNN’s reach above 98%. Meanwhile, Yolov5 has the faster computational speed than Faster-RCNN and Mask-RCNN. Comparatively speaking, with regard to the IP102 dataset whose background is complex and categories are abundant, Faster-RCNN and Mask-RCNN have the higher accuracy, reaching 99%, than Yolov5 whose accuracy is about 97%

Synthesis and photophysical properties of ruthenium(ii) polyimine complexes decorated with flavin

A bipyridine ruthenium(ii) complex (Ru-1) with a flavin moiety connected to one of the bipyridine ligands via an acetylene bond was designed and synthesized, and its photophysical properties were investigated. Compared with the tris(bipyridine) Ru(ii) complex (Ru-0), which has an extinction coefficient epsilon = 1.36 x 10(4) M-1 cm(-1) at 453 nm, the introduction of the flavin moiety endows Ru-1 with strong absorption in the visible range (epsilon = 2.34 x 10(4) M-1 cm(-1) at 456 nm). Furthermore, Ru-1 exhibits phosphorescence ((em) = 643 nm, phi(P) = 1%, (P) = 1.32 s at 293 K and 4.53 s at 77 K). We propose that the emission of Ru-1 originates from the low lying triplet excited state of (IL)-I-3 according to the time-resolved transient difference absorption spectra, the calculated T-1 spin density and the T-1 thermo-vibration modes localized on the flavin-decorated bipyridine ligand. This is the first time that the phosphorescence of flavin was observed within Ru(ii) complexes. Consequently, Ru-1 was used for triplet-triplet annihilation upconversion, showing a reasonable quantum yield of 0.7% with respect to the phosphorescence quantum yield of 1%. These findings pave the way for the rational design of phosphorescence transition metal complexes. Also, further approaches that may improve the performance of flavin-decorated Ru(ii) bipyridine complexes are proposed

Population Density and Driving Factors of North China Leopards in Tie Qiao Shan Nature Reserve

The North China leopard (Panthera pardus japonesis) is a rare leopard subspecies distributed only in China. In this study, we conducted camera-trap surveys of a North China Leopard population in Tie Qiao Shan Nature Reserve, Shanxi Province, China. We estimated population abundance and density distribution, and explored the effects of distribution of different prey populations, habitat, and anthropogenic factors on the spatial distribution of North China leopard density. Our results suggested that the North China leopard density was 4.23 individuals/100 km2, and that 17.98 individuals might live within the study area. The population density of the North China leopard increased with the distribution of wild boars, and, on the contrary, decreased with the distribution of roe deer. We found that habitat environmental factors and anthropogenic interference also significantly affected the population density and spatial distribution of the North China leopard. These insights informed us that in order to protect this predator, which is only distributed in China, we should adopt a comprehensive customized adaptive landscape protection strategy

Flavin Dibromide as an Efficient Sensitizer for Photooxidation of Sulfides

Flavin derivatives (FLs) are the building blocks and functional groups within many enzymes that absorb strongly in the visible light region and are redox cofactors in a large number of biological processes. We directly attached Br atoms into the conjugated framework of FL to afford FL dibromide (DBFL) and expected the heavy atom effect of Br to facilitate the intersystem crossing of excited FLs to reach the triplet states for efficient sensitization of O-2. Compared with FL (epsilon = 1.01 x 10(4) M-1 cm(-1) at 441 nm), DBFL shows stronger absorption in the visible range (epsilon = 1.90 x 10(4) M-1 cm(-1) at 450 nm). The singlet oxygen quantum yield of DBFL is enhanced from 55.3% in FL to 92.2% at the expense of decreased luminance quantum yield from 37.7% in FL to 5.5%, confirming that a large portion of the excited DBFL molecules evolves into triplet excited states. Both FL and DBFL were used in photosensitized oxidation of various sulfides to afford corresponding sulfoxides. DBFL exhibits a two-fivefold performance enhancement with respect to FL in sensitizing O-2 for photocatalytic oxidation. In addition, the oxidation of sulfides with DBFL was found efficient and led exclusively to sulfoxides, with no secondary oxidation products observed. Mechanistic investigations showed that both singlet oxygen and superoxide anion radical are formed as reactive oxygen species. The findings pave the way for design and application of novel organic sensitizers for photocatalytic oxidation