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Numerical analysis of wind effects on aerodynamic characteristics of a ducted fan

Chinese Journal of Aeronautics 2024年第5期37卷 263-280页

作者： yiwei LUO Tianfu ai Yuhang HE Bin XU Yuping QIAN Yangjun ZHANG State Key Laboratory of Intelligent Green Vehicle and Mobility School of Vehicle and MobilityTsinghua UniversityBeijing 100084China Key Laboratory of Conveyance and Equipment Ministry of Education East China Jiaotong UniversityNanchang 330013China Vehicle Research Center School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Ducted fans have been extensively used in Unmanned Aerial Vehicles(UAVs)for a variety of missions because of high efficiency,high safety and low ***,as a kind of typical meteorological condition,brings significant aerodynamic interference to the ducted fan,which seriously threatens flight stability and *** this work,the numerical simulation with the Unsteady Reynolds Averaged Navier-Stokes(URANS)method and the sliding mesh technique is performed to evaluate the steady wind *** results show that the wind will lead to serious unsteady effects in the flow field,and the thrust fluctuates at the blade passing frequency of 200 *** the wind speed increases,the rotor thrust increases,the duct thrust decreases,and the total thrust changes *** instability may occur when the wind speed exceeds 8 m/*** the angle of low-speed wind increases,the rotor thrust changes little,the duct thrust increases,and the total thrust *** addition,we figure out that cases with the same crosswind ratio are similar in results,and increasing the rotating speed or fan radius is beneficial to performance improvement in *** findings are essential to the ducted fan design and UAV flight control design for stable and safe operations in wind conditions.

关键词： Unmanned Aerial Vehicle(UAV) Ducted fan Wind effect Thrust fluctuations Computational Fluid Dynamics(CFD)

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A froth velocity measurement method based on improved U-Net++semantic segmentation in flotation process

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International Journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1816-1827页

作者： yiwei Chen Degang Xu Kun Wan School of Automation Central South UniversityChangsha 410083China

During flotation,the features of the froth image are highly correlated with the concentrate grade and the corresponding working *** static features such as color and size of the bubbles and the dynamic features such as velocity have obvious differences between different working *** extraction of these features is typically relied on the outcomes of image segmentation at the froth edge,making the segmentation of froth image the basis for studying its visual ***,the absence of scientifically reliable training data with label and the necessity to manually construct dataset and label make the study difficult in the mineral *** solve this problem,this paper constructs a tungsten concentrate froth image dataset,and proposes a data augmentation network based on Conditional Generative Adversarial Nets(cGAN)and a U-Net++-based edge segmentation *** performance of this algorithm is also evaluated and contrasted with other algorithms in this *** the results of semantic segmentation,a phase-correlationbased velocity extraction method is finally suggested.

关键词： froth flotation froth segmentation froth image data augmentation velocity extraction image features

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Amorphous hybrid tungsten oxide–nickel hydroxide nanosheets used as a highly efficient electrocatalyst for hydrogen evolution reaction

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Nano Research 2024年第4期17卷 2499-2508页

作者： Chao Lyu Chenghai Dai yiwei Tan State Key Laboratory of Materials-Oriented Chemical Engineering School of Chemistry and Chemical EngineeringNanjing Tech UniversityNanjing 211816China

There are more challenges for alkaline hydrogen evolution reaction(HER)via simultaneously expediting the electron-coupled water dissociation process(Volmer step)and the following electrochemical H_(2) desorption(Heyrovsky step).Hybrid amorphous electrocatalysts are highly desirable for efficient hydrogen evolution from water-alkali electrolyzers due to the bifunctionality for the different elementary steps of HER and optimal interactions with water molecules and the reactive hydrogen intermediates(Had).Herein,the synthesis of amorphous hybrid ultrathin(tungsten oxide/nickel hydroxide)hydrate(a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O)nanosheets on nickel foam(NF)for efficient alkaline HER is *** structural and composition features of a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O are characterized in *** resulting a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O/NF electrocatalyst with the synergistic effect of both hybrid components for the HER elementary steps shows greatly improved the activity and durability for the HER with a low overpotential of-41 and-163 mV at-10 and-500 mA·cm^(-2),respectively,a Tafel slope as low as-72.9 mV·dec^(-1),and long-term stability of continuous electrolysis for at least 150 h accompanying by inappreciable overpotential change in 1 M *** the hybrid a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O,Ni(OH)_(2) and WO_(3) moieties are separately responsible for accelerating dissociative adsorption of water and weakening Had adsorption strength,which is beneficial to the improvement of the alkaline HER activity.

关键词： amorphous nanomaterial bimetallic electrocatalyst tungsten oxide ultrathin nanosheet hydrogen evolution reaction

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Imaging of human parafoveal area with large field of view in adaptive optics line scanning ophthalmoscope

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Journal of Innovative Optical Health Sciences 2024年第6期17卷 41-51页

作者： Wen Kong yiwei Chen Guohua Shi Yi He Department of Biomedical Engineering University of Science and Technology of ChinaHefei 230041P.R.China Jiangsu Key Laboratory of Medical Optics Suzhou Institute of Biomedical Engineering and TechnologyChinese Academy of SciencesSuzhou 215163P.R.China Center for Excellence in Brain Science and Intelligence Technology Chinese Academy of SciencesShanghai 200031P.R.China Key Laboratory of Myopia of State Health Ministry and Key Laboratory of Visual Impairment and Restoration of ShanghaiShanghai 200003P.R.China

The parafoveal area,with its high concentration of photoreceptors andfine retinal capillaries,is crucial for central vision and often exhibits early signs of pathological *** current adaptive optics scanning laser ophthalmoscope(AOSLO)provides an excellent tool to acquire accurate and detailed information about the parafoveal area with cellular ***,limited by the scanning speed of two-dimensional scanning,thefield of view(FOV)in the AOSLO system was usually less than or equal to 2,and the stitching for the parafoveal area required dozens of images,which was time-consuming and ***,almost half of patients are unable to obtain stitched images because of their *** solve this problem,we integrate AO technology with the line-scan imaging method to build an adaptive optics line scanning ophthalmoscope(AOLSO)system with a larger *** the AOLSO,afocal spherical mirrors in pairs are nonplanar arranged and the distance and angle between optical elements are optimized to minimize the aberrations,two cylinder lenses are orthogonally placed before the imaging sensor to stretch the point spread function(PSF)for su±ciently digitizing light *** human retinal images show the whole parafoveal area with 55FOV,60 Hz frame rate and cellular *** advantage of the 5FOV of the AOLSO,only 9 frames of the retina are captured with several minutes to stitch a montage image with an FOV of 99,in which photoreceptor counting is performed within approximately 5*** AOLSO system not only provides cellular resolution but also has the capability to capture the parafoveal region in a single frame,which offers great potential for noninvasive studying of the parafoveal area.

关键词： Adaptive optics line scanning retinal imaging system parafoveal capillary vasculature.

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Multi-scale physics-informed neural networks for solving high Reynolds number boundary layer flows based on matched asymptotic expansions

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 76-81页

作者： Jianlin Huang Rundi Qiu Jingzhu Wang yiwei Wang Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Future Technology University of Chinese Academy of SciencesBeijing 100049China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China Guangdong Aerospace Research Academy Guangzhou 511458China

Multi-scale system remains a classical scientific problem in fluid dynamics,biology,*** the present study,a scheme of multi-scale Physics-informed neural networks is proposed to solve the boundary layer flow at high Reynolds numbers without any *** flow is divided into several regions with different scales based on Prandtl's boundary *** regions are solved with governing equations in different *** method of matched asymptotic expansions is used to make the flow field continuously.A flow on a semi infinite flat plate at a high Reynolds number is considered a multi-scale problem because the boundary layer scale is much smaller than the outer flow *** results are compared with the reference numerical solutions,which show that the msPINNs can solve the multi-scale problem of the boundary layer in high Reynolds number *** scheme can be developed for more multi-scale problems in the future.

关键词： Physics-informed neural networks(PINNs) Multi-scale Fluid dynamics Boundary layer

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Heat Recuperation for the Self-Condensing CO_(2)Transcritical Power Cycle

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Journal of Thermal Science 2024年第5期33卷 1630-1641页

作者： PAN Lisheng SHI Weixiu SUN Yin SUN yiwei WEI Xiaolin State Key Laboratory of High-temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Environment and Energy Engineering Beijing University of Civil Engineering and ArchitectureBeijing 100044China

The supercritical CO_(2)Brayton cycle has potential to be used in electricity generation occasions with its advantages of high efficiency and compact *** on a so-called self-condensing CO_(2)transcritical power cycle,a model was established and four different layouts of heat recuperation process were analyzed,a without-recuperation cycle,a post-recuperation cycle,a pre-recuperation cycle and a re-recuperation *** results showed that the internal normal cycle's share of the whole cycle increases with increasing the cooling pressure and decreasing the final cooled *** load in the supercritical heater decreases with increasing the cooling *** perspective of performance,the re-recuperation cycle and the pre-recuperation cycle have similar thermal efficiency which is much higher than other two *** thermal efficiency and net power output have a maximum value with the cooling pressure,except in the condition with the final cooled temperature of 31℃.Considering both the complexity and the economy,the pre-recuperation cycle is more applicable than the other *** 35℃of the final cooled temperature,the thermal efficiency of the pre-recuperation cycle reaches the peak 0.34 with the cooling pressure of 8.4 MPa and the maximum net power output is 2355.24 kW at 8.2 MPa of the cooling pressure.

关键词： CO_(2)transcritical power cycle heat recuperation process self-condensing

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Solar fuel production through concentrating light irradiation

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Green Energy & Environment 2024年第10期9卷 1550-1580页

作者： yiwei Fu Yi Wang Jie Huang Kejian Lu Maochang Liu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow Xi'an Jiaotong University Suzhou Academy of Xi'an Jiaotong University

The climate crisis necessitates the development of non-fossil energy sources. Harnessing solar energy for fuel production shows promise and offers the potential to utilize existing energy infrastructure. However, solar fuel production is in its early stages of development, constrained by low conversion efficiency and challenges in scaling up production. Concentrated solar energy(CSE) technology has matured alongside the rapid growth of solar thermal power plants. This review provides an overview of current CSE methods and solar fuel production, analyzes their integration compatibility, and delves into the theoretical mechanisms by which CSE impacts solar energy conversion efficiency and product selectivity in the context of photo-electrochemistry, thermochemistry, and photo-thermal co-catalysis for solar fuel production. The review also summarizes approaches to studying the photoelectric and photothermal effects of CSE. Lastly, it explores emerging novel CSE technology methods in the field of solar fuel production.

关键词： Concentrated solar energy Solar fuel Photo-electrochemistry Thermochemistry Photo-thermal co-catalysis

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Development of EPDM composites reinforced by CNTs@SiO_(2)for thermal protection systems of aerospace propulsion:Significant improvement in oxidation and ablation resistance properties

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Chinese Journal of Aeronautics 2024年第2期37卷 471-481页

作者： Li WANG Jiang LI Kang LI yiwei WANG Chenyang MA Science and Technology on Combustion Internal Flow and Thermal-Structure LaboratoryNorthwestern Polytechnical UniversityXi’an 710072China

Carbon Nanotubes(CNTs)reinforced Polymer-Matrix Composites(PMCs)is widely used as insulation materials in thermal protection system of aerospace ***,CNTs are prone to oxidation and have high thermal conductivities,which makes it difficult to improve the ablation resistance of insulation materials that contain ***_(2)was encapsulated onto the surface of CNTs(CNTs@SiO_(2)),which were then added to Ethylene Propylene Diene Monomer(EPDM)rubber to prepare the insulation *** analysis and ablation test were used to evaluate the resistance of the insulation materials to thermal oxidation and ***,scanning electron microscopy was performed to analyze their *** revealed that the addition of CNTs@SiO_(2)could visibly reduce the effects of hot corrosion and ablation on insulation *** C-CNTs@SiO_(2)-1 formulation had the best ablative ***,compared with the unencapsulated formulation(C-CNTs-10),the C-CNTs@SiO_(2)-1 formulation reduced the line ablation rate by 51%to 0.0130 mm/s after oxygen-acetylene ***,the ablation mechanism was investigated based on the effects of the CNTs@SiO_(2)additive on their ***,the improvement in ablation performance may be attributed to CNTs@SiO_(2)-induced decreases in thermal conductivity,improvement in the hot corrosion resistance in the char layer,and changes in the microstructure.

关键词： Polymer-Matrix Composites(PMCs) Carbon Nanotubes(CNTs) Thermal properties Ablation Oxidation

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Pathogenic genes associated with Parkinson’s disease:molecular mechanism overview

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BIOCELL 2024年第5期48卷 707-729页

作者： TINGTING LIU yiwei HAO LIFENG ZHAO School of Life Sciences Institute for Brain Sciences ResearchHenan UniversityKaifeng475004China Pharmaceutical Department Peking University Cancer Hospital Inner Mongolia HospitalHohhot010010China

Parkinson’s disease(PD)is a common neurodegenerative disease in the elderly,accounting for more than 1%of the population aged 65 *** inheritance is relatively rare in PD,accounting for approximately 5%to 10%of PD patients,and there is a growing body of evidence suggesting that multiple genetic risk factors play a significant role in the pathogenesis of *** groups have identified and reported a number of genes carrying mutations associated with affected family *** genes associated with PD are also candidates for idiopathic PD,and these genes may also carry other mutation sites that increase *** multiple genetic risk factors are combined,the risk of PD is increased to a greater extent,and to unravel the pathogenic pathways that lead to different forms of *** review focuses on the association of PD genes,such as Parkinson Disease 1-24(PARK1-24),glucosylceramidase(GBA),GTP cyclohydrolase 1(GCH1),fibroblast growth factor 20(FGF20),nuclear receptor-related factor 1(NURR1),NUS1 dehydrodolichyl diphosphate synthase subunit(NUS1),diacylglycerol Lipase Beta(DAGLB),transmembrane protein(TMEM),ubiquinol-cytochrome c reductase core protein 1(UQCRC1),glycoprotein non-metastatic melanoma protein B protein(GPNMB),dynactin 1(DCTN1),LDL receptor related protein 10(LRP10),monoamine oxidase(MAO),ataxin 2(ATXN2),microtubule associated protein tau(MAPT),pantothenate kinase 2(PANK2),spastic parapplegia type 11(SPG11),polymer gamma(POLG),TATA-box binding protein associated factor 1(TAF1),dual specificity tyrosine phosphorylation regulated kinase 1A(Dyrk1a),and crystallin alpha A(CRYAA),with the pathogenesis of *** introduce what is currently known about the molecular genetics of PD to help explain the molecular mechanisms leading to the neurodegenerative disease.

关键词： Parkinson’s disease(PD) Molecular genetics Mutation

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An Advanced Image Processing Technique for Backscatter-Electron Data by Scanning Electron Microscopy for Microscale Rock Exploration

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Journal of Earth Science 2024年第1期35卷 301-305页

作者： Zhaoliang Hou Kunfeng Qiu Tong Zhou yiwei Cai Frontiers Science Center for Deep-time Digital Earth China University of GeosciencesBeijing 100083China Department of Geology University of ViennaVienna 1090Austria State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences and ResourcesChinaUniversity of GeosciencesBeijing 100083China

Backscatter electron analysis from scanning electron microscopes(BSE-SEM)produces high-resolution image data of both rock samples and thin-sections,showing detailed structural and geochemical(mineralogical)*** allows an in-depth exploration of the rock microstructures and the coupled chemical characteristics in the BSE-SEM image to be made using image processing *** image processing is a powerful tool for revealing the more subtle data“hidden”in a picture,it is not a commonly employed method in geoscientific microstructural ***,we briefly introduce the general principles of image processing,and further discuss its application in studying rock microstructures using BSE-SEM image data.

关键词： Image processing rock microstructures electron-based imaging data mining

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