Abstract The article proposes a real‐time apple picking method based on an improved YOLOv5. This method accurately recognizes different apple targets on fruit trees for robots and helps them adjust ...their position to avoid obstructions during fruit picking. Firstly, the original BottleneckCSP module in the YOLOv5 backbone network is enhanced to extract deeper features from images while maintaining lightweight. Secondly, the ECA module is embedded into the improved backbone network to better extract features of different apple targets. Lastly, the initial anchor frame size of the network is adjusted to avoid recognizing apples in distant planting rows. The results demonstrate that this improved model achieves high accuracy rates and recall rates for recognizing various types of apple picking methods with an average recognition time of 0.025s per image. Compared with other models tested on six types of apple picking methods, including the original YOLOv5 model as well as YOLOv3 and EfficientDet‐D0 algorithms, our improved model shows significant improvements in mAP by 1.95%, 17.6%, and 12.7% respectively. This method provides technical support for robots' picking hands to actively avoid obstructions caused by branches during fruit harvesting, effectively reducing apple loss.
This paper evaluates the recoverable unconventional oil and gas resources around the world, reveals main controlling factors and potential regions for the rich accumulation of unconventional oil and ...gas, and standardizes the classification of seven types of resources (i.e., heavy oil, oil sand, tight oil, oil shale, shale gas, tight gas, and coalbed methane). By virtue of commercial databases for global petroliferous basins, together with single-well data packages in North America and basic data of exploration and development of Chinese companies in unconventional oil and gas resources blocks around the world, contour maps of abundance for global recoverable resources are formed through spatial graphic interpolation of key assessment parameters of seven types of unconventional oil and gas resources on the Geographic Information System (GIS) platform, which systematically evaluate the potential of seven types of unconventional oil and gas resources. The assessment reveals: (1) These seven types of resources around the world are distributed predominantly in 476 formations in 363 petroliferous basins. (2) Total recoverable unconventional oil and gas resources in the world are respectively 442.1 billion tons and 227 trillion cubic meters. (3) Unconventional oil and gas resources can be divided into “source-bound type” and “strata-bound type”. The “source-bound type” resources are mainly controlled by 6 groups of high-quality source rock around the world, among which, the tight oil and gas resources are featured by the “integration of reservoir and source”, presenting the best prospect for the development and application, and the “strata-bound type” oil sand and heavy oil resources, controlled by the transformation of the late structure, are mainly distributed in the slope belt of the Mesozoic-Cenozoic basins, presenting a good prospect for the resource development and application in the shallow layers. (4) Besides hot spots in North America, tight oil in the West Siberia Basin and the Neuquen Basin as well as heavy oil in the Arab Basin will become potential targets for the development of unconventional oil and gas resources in the future.
CaF2 nanoparticles doped with different Er concentrations were synthesized by a co-precipitation method. The phase compositions and morphology of the obtained Er:CaF2 nanoparticles were characterized ...by X-ray diffraction and transmission electron microscopy analysis. It was found that the size and shape of obtained CaF2 nanoparticles were modified through Er3+ doping. High quality Er:CaF2 transparent ceramics were fabricated by hot-pressed sintering method in a vacuum environment. The influence of Er3+ doping concentrations and sintering temperatures on optical transmission and microstructure of Er:CaF2 transparent ceramics were investigated. When doped with 5 mol% Er3+, the CaF2 ceramic sintered at 800 °C showed the best optical transmission, and for the 2 mm thickness sample, the optical transmission reached about 90% in the near-infrared spectral region.
•Er:CaF2 nanoparticles were synthesized by coprecipitation method.•The size and shape of CaF2 nanoparticles were modified through Er doping.•Influence of Er content on transmissivity and microstructure was investigated.•Influence of temperature on transmissivity and microstructure was investigated.
Nanoparticles of Yb, Er codoped calcium fluoride were obtained by a co-precipitation method. Scanning electron microscope (SEM) and X-ray powder diffraction (XRD) analysis showed that the obtained ...nanoparticles were single fluorite phase with grains size around 30–50nm. Yb, Er:CaF2 transparent ceramics were fabricated by hot pressing (HP) the nanoparticles at a temperature of 800°C in a vacuum environment. For a 2mm thickness ceramic sample, the transmittance at 1200nm reached about 83%. Microstructures were characterized using SEM analysis, and the average grain size was about 700nm. Grain boundaries of the ceramic sample were clean and no impurities were detected. The absorption, upconversion and infrared emission spectra of transparent ceramic sample under 978nm excitation were measured and discussed.
Silica nanoparticles (SiNPs) have been widely used in electronics, chemistry, and biomedicine. Human exposure to SiNPs and possible health effects have attracted much attention. The potential ...cardiovascular toxicity of SiNPs and their related mechanisms are still unclear. Therefore, in this study, we investigated the toxic effects of SiNPs on human umbilical vein endothelial cells (HUVECs). We found that SiNPs could induce HUVECs ferroptosis. The results showed that the level of intracellular divalent iron and lipid peroxidation increased, and mitochondrial cristae decreased. In addition, the pretreatment of the iron chelator deferoxamine mesylate (DFO) could alleviate the ferroptosis of cells. Interestingly, pretreatment of 3-methyladenine (3-MA), an autophagy/PI3K inhibitor could partially inhibit autophagy and reduce ferroptosis, which indicated that autophagy played an important role in cell ferroptosis. Additionally, after knocking down nuclear receptor coactivator 4 (NCOA4), Ferritin Heavy Chain 1 (FTH1) expression was up-regulated, and the levels of divalent iron and lipid peroxidation decreased, which suggested that NCOA4 mediated the ferroptosis of HUVECs induced by SiNPs. In conclusion, this study shows that SiNPs can induce cardiovascular toxicity in which there is ferroptosis. NCOA4-mediated ferritinophagy and resultant ferroptosis by SiNPs may play an important role. This study provides a new theoretical strategy for the treatment and prevention of cardiovascular diseases in the future.
A novel layered transparent Er:CaF2 composite ceramic was proposed in the present study. Er:CaF2 nanoparticles were synthesized by a chemical coprecipitation method. The crystal structures and ...morphologies of synthesized nanoparticles were performed by X‐ray diffraction (XRD) and field emission scanning electron microscope (FE‐SEM) measurements, respectively. Transparent composite ceramic was fabricated by the combination of multistep dry pressing and hot‐pressed sintering method without any sintering aids or binders. The average grain size of 2% Er‐doped and 5% Er‐doped layers were about 30 and 55 μm, respectively. The thickness of interfacial between two different Er‐doped layers was 150‐200 μm. For a 1.5 mm thickness transparent Er:CaF2 composite ceramic, the optical transmittance reached 44.9% at 500 nm and 53.6% at 1200 nm. The luminescence spectra and thermal conductivities of transparent ceramic specimens were also discussed.
Boiler emissions are the primary sources of atmospheric nitrogen oxide (NOx) emissions. Exceeding the NOx emission limit can shut down the boiler, causing financial losses. Herein, a new preheated ...combustion method is proposed to prevent coal-fired boilers from exceeding the NOx emission limit at low loads. This is a simulation study of internal combustion burners and a 600 MW tangentially fired boiler using a pulverized coal preheating method that explores syngas production patterns after pulverized coal is preheated, the effects of flow characteristics, and variations in NOx and unburned carbon content under different preheating ratios. Our results indicated that the internal combustion burner had a stable preheating effect. The volume fractions of CH4, CO, and H2 at the burner outlet were 0.95%, 12.7%, and 0.8%, respectively. The fuel nitrogen precipitated during the preheating process was converted into N2. High-temperature char and syngas entered the furnace chamber and were mixed with air to accelerate combustion, which enhanced the jet flow intensity and improved the combustion stability at 50% load. The top burner exhibited a more significant nitrogen reduction than the bottom burner. The NO reduction from retrofitting Layers D and E accounted for 53% after retrofitting all five layers. When the preheating ratio was increased from 0 to 100%, NOx concentration was reduced by 63.6% at 6% O2, while unburned carbon content was reduced by 41%, which improved combustion efficiency. By discussing the advantages of internal combustion burners for retrofitting a 600 MW tangentially fired boiler, this study provides theoretical guidance for the application of preheating methods in peaking conditions.
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In this study, a noninvasive and nondestructive microcalorimetric method was used to investigate the antimicrobial activity of three anthraquinone derivatives (emodin, aloe-emodin and physcion) from ...Chinese Rhubarb. Additionally, we observed a synergistic antibacterial effect of a mixture (emodin + aloe-emodin) on
Staphylococcus aureus
. Antibacterial effects were further evaluated through principle component analysis and the half-inhibitory concentration (IC
50
) according to the influence of the anthraquinone derivatives on eight quantitative thermokinetic parameters, which were measured by isothermal microcalorimetry and obtained from metabolic power–time curves of
Staphylococcus aureus
growth at 37 °C. The inhibitory actions of the anthraquinone derivatives varied at different concentrations. The antibacterial effect of the derivatives on
S. aureus
was as follows: emodin + aloe-emodin (E + AE) > emodin (E) > aloe-emodin (AE) > physcion. Based on these results, the combined effect of emodin and aloe-emodin was stronger than that of each anthraquinone derivative alone. The combination of emodin and aloe-emodin is a promising antibacterial agent, providing a novel avenue for antibacterial materials.
In this work, Er:CaF2 transparent ceramic codoped with non-active ions (Y3+ ions) was fabricated by hot-pressed (HP) sintering method. Er and Er/Y codoped CaF2 nanoparticles were synthesized by a ...simple coprecipitation method, the phase composition and the shape of obtained nanoparticles were analysed by X-ray diffraction patterns and transmission electron microscopy, respectively. Fluorite transparent ceramics were fabricated by HP sintering method at a temperature of 800°C. For 2mm thickness ceramic samples, the optical transmission of Er, Y:CaF2 transparent ceramic in the near-infrared range reached about 90%, and the optical transmission of Er, Y:CaF2 transparent ceramic was much higher than Er:CaF2 ceramic sample. Microstructures were characterized using SEM analysis, the two ceramic samples exhibited nearly pore-free microstructure and the average grain sizes were less than 1.0μm. The absorption, upconversion and infrared emission spectras of ceramic samples were also measured and discussed.
Fouling deposition problem on heat transfer surface is widely distributed in the field of energy and chemical industry, and microbial fouling is a common fouling type in heat exchanger. In this ...article, the surface modification was used for inhibiting or mitigating the microbial fouling deposition on heat exchange surface. Firstly, the experimental system for real-time monitoring the fouling deposition process was built, and then the Ni-P modified surface was prepared. Further, the slime forming bacteria (SFB) microbial fouling characteristics and corresponding influencing factors on Ni-P modified surface were investigated experimentally. The results indicated that Ni-P modified surface had an excellent fouling inhibition property. Comparing with carbon steel, Ni-P modified surface reduced the fouling heat resistance by 80%. Accordingly, the influencing factors of microbial fouling deposition including temperature, flow rate and microbial concentrations were discussed. With cooling water temperature increasing given in the experiment arrangement, the microbial fouling resistance was increased first and then decreased, while with bacteria concentration and flow rate increasing, the fouling resistance was increased and decreased separately. The work can provide experimental reference for the fouling inhibition surface development and fouling inhibition mechanism study.
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