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On the electric behaviour of conductive grease inside the contact zone

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Friction 2024年第4期12卷 683-697页

作者： Yuxin ZHOU Jinjie LIU Xinming LI He CHONG Bo HAN Qinghua bai SKF(Shanghai)Automotive Technologies Co. Ltd.Shanghai 201814China School of Mechanical and Automotive Engineering Qingdao University of TechnologyQingdao 266250China

Conductive grease has been considered as a potential solution in addressing electric erosion issue inside motor *** the conductive grease performance,especially the electric and tribological behaviour is crucial for its *** paper combines bulk grease characterization and contact film study considering both electrical and tribological loading *** results show that the electric performance for the selected conductive grease sample is electric field dependent,including both frequency and voltage *** film impedance inside the contact area is closely related to the external electric field,running condition,and lubrication *** following film impedance calculation tells that not only bulk grease electric parameters,but the contact parameter,lubricant film contour and lubrication condition should be considered when performing the overall bearing electrical modelling.

关键词： Electric erosion lubricant conductivity grease film impedance

Observing eddy dye patches induced by shear instabilities in the surf zone on a plane beach

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Acta Oceanologica Sinica 2024年第3期43卷 15-29页

作者： Chunping Ren Nannan Fu Chong Yu Yuchuan bai Kezhao Fang State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China College of Water Resource Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

The effects of surf zone eddy generated by alongshore currents on the deformation and transport of dye are still poorly understood,and related tracer release experiments are ***,a tracer release laboratory experiment was conducted under monochromatic,unidirectional incident waves with a large incident angle(30°)on a plane beach with a 1:100 slope in a large wave basin.A charge-coupled device suspended above the basin recorded the dye patch *** evolution of eddy dye patch was observed and the transport and diffusion were analyzed based on the collected ***,a linear instability numerical model was adopted to calculate the perturbation velocity field at the initial *** observation and image processing results show that surf zone eddy patches occurred and were separated from the original dye *** numerical analysis results demonstrate that the structure of the perturbation velocity field is consistent with the experimental observations,and that the ejection of eddy patches shoreward or offshore may be ascribed to the double vortex.

关键词： surf zone tracer release experiment evolution of eddy patch shear instability of alongshore currents

Hydrodynamic analysis of carbon nanotube clusters in distributor-less conical fluidized beds with step-by-step scaling

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Chinese Journal of Chemical Engineering 2024年第3期67卷 117-125页

作者： Tianle Zhang Wenjuan bai Qianpeng Dong Dianming Chu Lianlian Wang Yan He Shandong Engineering Laboratory for Preparation and Application of High-performance Carbon-Materials College of Electromechanical EngineeringQingdao University of Science and TechnologyQingdao 266061China Shandong Dazhan Nano Materials Co. Ltd.Binzhou 256220China

As a high-performance material with great application potential,the application of carbon nanotubes has been limited by their production volume.A distributor-less conical fluidized bed is the main equipment used in the industrial production of carbon *** improve the production volume and product quality of carbon nanotubes,the study of fluidized-bed-diameter scaling is *** different diameters of distributor-less conical fluidized beds were established,and then the particle behavior and bubble characteristics of carbon nanotube clusters at these bed diameters were ***-series and wavelet analysis methods were used to analyze the pressure-fluctuation signals inside the fluidized *** showed that the distributor-less design caused the airflow to break through the middle of the bed,which did not change with the change in bed *** powder-bridging phenomenon of carbon nanotube clusters in a 100-mm-diameter fluidized bed was related to the special microstructure of carbon nanotube *** frequency of pressure fluctuations in the bed decreased nonlinearly with increasing bed *** study can guide the design and scale-up of distributor-less conical fluidized beds,especially for the scale-up of carbon nanotube production equipment,which can contribute to the improvement of carbon nanotubes’capacity and quality in industrial production.

关键词： Carbon nanotubes Fluidized bed Multiphase flow Scale-up Multiscale

Unbound^(28)O,the heaviest oxygen isotope observed:a cutting-edge probe for testing nuclear models

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Nuclear Science and Techniques 2024年第2期35卷 1-2页

作者： Jian-Guo Li bai-Shan Hu Shuang Zhang Fu-Rong Xu School of Physics and State Key Laboratory of Nuclear Physics and TechnologyPeking UniversityBeijing 100871China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Southern Center for Nuclear-Science Theory(SCNT) Institute of Modern PhysicsChinese Academy of SciencesHuizhou 516000China

The beyond-dripline oxygen isotopes^(27,28)O were recently observed at RIKEN,and were found to be unbound decaying into^(24)O by emitting *** unbound feature of the heaviest oxygen isotope,^(28)O,provides an excellent test for stateof-the-art nuclear *** atomic nucleus is a self-organized quantum manybody system comprising specific numbers of protons Z and neutrons N.

关键词： testing quantum system

Flow characteristics of radial inflow in impeller rear cavity with baffle plate

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Chinese Journal of Aeronautics 2024年第2期37卷 270-282页

作者： Yang bai Xiang LUO Dongdong LIU Zeyu WU Xiaoqiang ZHANG Sipeng WANG Research Institute of Aero-Engine Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBeijing 100191China

The research purpose of this paper is to explore the influence of the baffle plate on the airflow in the rear cavity of the centrifugal impeller and optimize the performance of the secondary air system’s air bleed *** this paper,a comprehensive experimental study was carried out on the flow characteristics in the impeller rear cavity with baffle *** windage torque,flow structure and pressure drop between inlet and outlet were measured *** experiment was carried out with the condition that the range of rotational Reynolds number was from 8.33×10^(5)to 22.2×10^(5)and the range of mass flow rate coefficient was from 0.92×10^(4)to 2.92×10^(4).The results show that the static cavity and the narrow stator-rotor cavity formed by the baffle plate effectively suppress the overall swirl coefficient in the ***,the static pressure and total pressure drop in the rotor-stator cavity were *** influence of the baffle plate on the windage torque of the rotary disk is related to the turbulence *** large turbulence parameters,the windage torque would be reduced with baffle plate,while under small turbulence parameters,the baffle plate would increase with baffle *** general,the baffle plate can improve the flow capacity and optimize the bleed air performance with proper structure and operation conditions.

关键词： Impeller rear cavity Baffle plate Flow structure Windage torque Pressure drop

A New Method for the Aging Evaluation of Oil-Paper Insulation Using η-Butanol and Methanol

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 717-726页

作者： Jianyi Wang Yuanxiang Zhou Jun Liu Zhaowei Wang Song bai Jiayu Lu Department of High Voltage China Electric Power Research InstituteBeijing 100192China State Key Laboratory of Power Grid Environmental Protection Beijing 100192China Electrical Engineering Department Tsinghua UniversityBeijing 100084China Solar Storage Division of State Key Lab of Power System and Generation Equipment School of Electrical EngineeringXinjiang UniversityUrumqi 830047China State Grid Wuwei Electric Power Supply Company Wuwei 733000China

To improve the accuracy and efficiency of the aging life prediction and assessment of transformer oil-paper insulation,and to make up for the deficiencies of traditional characterizers,such as 2-furfural,carbon monoxide,and carbon dioxide,a method for the simultaneous determination of methanol,ethanol,n−propanol,and η-butanol in oil with a single injection is established by headspace-gas chromatography-mass *** measured results show that the determination limits of the four alcohol characterizers can be controlled to 10μg/kg *** on this method,the change patterns of the above four alcohols with thermal aging time and degree of polymerization are obtained through thermal aging experimental ***,η-propanol,and η-butanol in oil indicate nearly linear correlations with thermal aging time and degree of polymerization,similar to that of *** analyzing 52 sets of measured data of 500 kV EHV transformers in operation,η-butanol is found to have excellent performance,and a new method to evaluate the aging state of oil-paper insulation employing η-butanol and methanol is proposed along with the aging attention value *** measured data of 500 kV EHV transformers in operation indicate that the combination of η-butanol and methanol as the preferred characterizers can effectively compensate for the shortcoming of traditional characterizers in the early stages of aging,and the feasibility of the method is *** possible pathways for the generation of η-butanol by cellulose cleavage during the aging of oil-paper are proposed from the chemical structure of cellulose.

关键词： Aging characterization determination method methanol η-butanol oil-paper insulation 500 kV transformers

Flower-like tin oxide membranes with robust three-dimensional channels for efficient removal of iron ions from hydrogen peroxide

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Chinese Journal of Chemical Engineering 2024年第1期65卷 1-7页

作者： Risheng Shen Shilong Li Yuqing Sun Yuan bai Jian Lu Wenheng Jing State Key Laboratory of Materials-Oriented Chemical Engineering Nanjing Tech UniversityNanjing 210009China National Energy Group Science and Technology Research Institute Co. Ltd.Nanjing 210023China

Membrane technology has become the mainstream process for the production of electronic grade hydrogen peroxide(H_(2)O_(2)).But due to the oxidation degradation of the organic membranes(***)by the strong oxidative radicals(e.g.OH)generated via the activation of H_(2)O_(2)by iron ions(Fe^(3+)),the short effective lifetime of membranes remains a *** nano tin oxide(SnO_(2))has great potential for the removal of Fe^(3+)in strongly oxidative H_(2)O_(2)because of its ability to stabilize H2O_(2)and preferentially adsorb Fe^(3+).Herein,we have designed for the first time a flower-like robust SnO_(2)membrane on the ceramic support by in situ template-free one-step hydrothermal *** three-dimensional loose pore structure in the membrane built by interlacing SnO_(2)nanosheets endows the SnO_(2)membrane with a high specific surface area and abundant adsorption sites(AOH).Based on the coordination complexation and electrostatic attraction between the SnO_(2)surface and Fe^(3+),the membrane shows a high Fe3+removal efficiency(83%)and permeability(24 L·m^(-2)·h^(-1)·MPa^(-1))in H_(2)O_(2).This study provides an innovative and simple approach to designing robust SnO_(2)membranes for highly efficient removal of Fe^(3+)in harsh environments,such as strong oxidation conditions.

关键词： Hydrogen peroxide SnO_(2)membrane Adsorption Hydrothermal

Two diversities meet in the rhizosphere:root specialized metabolites and microbiome

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Journal of Genetics and Genomics 2024年第5期51卷 467-478页

作者： Xiaochen Wang Jingying Zhang Xinjun Lu Yang bai Guodong Wang State Key Laboratory of Plant Genomics Institute of Genetics and Developmental BiologyThe Innovative Academy of Seed DesignChinese Academy of SciencesBeijing 100101China CAS-JIC Centre of Excellence for Plant and Microbial Science Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing 100101China Hainan Yazhou Bay Seed Laboratory SanyaHainan 572025China College of Advanced Agricultural Sciences Chinese Academy of SciencesBeijing 100049China

Plants serve as rich repositories of diverse chemical compounds collectively referred to as specialized *** compounds are of importance for adaptive processes,including interactions with various microbes both beneficial and *** microbes as bioreactors,the chemical diversity undergoes dynamic changes when root-derived specialized metabolites(RSMs)and microbes encounter each other in the *** advancements in sequencing techniques and molecular biology tools have not only accelerated the elucidation of biosynthetic pathways of RSMs but also unveiled the significance of RSMs in plant-microbe *** this review,we provide a comprehensive description of the effects of RSMs on microbe assembly in the rhizosphere and the influence of corresponding microbial changes on plant health,incorporating the most up-to-date information ***,we highlight open questions that remain for a deeper understanding of and harnessing the potential of RSM-microbe interactions to enhance plant adaptation to the ***,we propose a pipeline for investigating the intricate associations between root exometabolites and the rhizomicrobiome.

关键词： Root specialized metabolites Microbiome Plant-microbe interactions Rhizosphere Diversity

Optimized Mask-RCNN model for particle chain segmentation based on improved online ferrograph sensor

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Friction 2024年第6期12卷 1194-1213页

作者： Shuo WANG Miao WAN Tonghai WU Zichen bai Kunpeng WANG Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an Jiaotong UniversityXi’an 710049China

Ferrograph-based wear debris analysis(WDA)provides significant information for wear fault analysis of mechanical *** decades of offline application,this conventional technology is being driven by the online ferrograph sensor for real-time wear state ***,online ferrography has been greatly limited by the low imaging quality and segmentation accuracy of particle chains when analyzing degraded lubricant oils in practical *** address this issue,an integrated optimization method is developed that focuses on two aspects:the structural re-design of the online ferrograph sensor and the intelligent segmentation of particle *** enhancing the imaging quality of wear particles,the magnetic pole of the online ferrograph sensor is optimized to enable the imaging system directly observe wear particles without penetrating ***,a light source simulation model is established based on the light intensity distribution theory,and the LED installation parameters are determined for particle illumination uniformity in the online ferrograph *** this basis,a Mask-RCNN-based segmentation model of particle chains is constructed by specifically establishing the region of interest(ROI)generation layer and the ROI align layer for the irregular particle *** these measures,a new online ferrograph sensor is designed to enhance the image acquisition and information extraction of wear *** verification,the developed sensor is tested to collect particle images from different degraded oils,and the images are further handled with the Mask-RCNN-based model for particle feature *** results reveal that the optimized online ferrography can capture clear particle images even in highly-degraded lubricant oils,and the illumination uniformity reaches 90%in its imaging *** importantly,the statistical accuracy of wear particles has been improved from 67.2%to 94.1%.

关键词： wear particle analysis online ferrography particle image acquisition particle chain segmentation