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Experimental and numerical investigation of the impacts of rotor tip-rake on excitation forces of pump-jet propulsors

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Journal of Hydrodynamics 2024年第1期36卷 142-157页

作者： Xue-qin Ji xiao-song Zhang Chen-jun Yang xiao-qian Dong State Key Laboratory of Ocean Engineering Marine Numerical Experiment CentreSchool of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China CSSC Shanghai Marine Energy Saving Technology Co. Ltd.Shanghai200011China China Ship Scientific Research Center Shanghai Branch Shanghai200011China

The tip-clearance flow in a pump-jet propulsor exerts great impacts on the fluctuating pressures and resultant unsteady forces,which are important sources of structural vibrations and radiated noise *** blade geometry close to the tip is an important factor determining the vortex strength in the tip-clearance *** the open-water condition,the effects of raking the rotor tips on the duct-surface fluctuating pressures and the resultant unsteady forces acting on different components of the propulsor are investigated via physical model experiments and the numerical solution of Reynolds-averaged Navier-Stokes(RANS)equations coupled with the SST k-ωturbulence *** measured and simulated results of hydrodynamic pressures are consistent to each other,and the simulated flows help better understand why the fluctuating pressures change with the tip *** strong fluctuations of duct-surface pressures are caused by intensive tip separation *** duct-surface pressure fluctuations are effectively reduced by using the rake distribution near the tip towards blade back side and,for the combination of the five-bladed rotor and the seven-bladed stator,the resultant unsteady horizontal(and vertical)forces acting on the duct and stator are also reduced;while increasing rake leads to negative effect on pressure fluctuations and unsteady horizontal(and vertical)forces acting on all the components of the propulsor.

关键词： Pump-jet tip-clearance tip-rake fluctuating pressures excitation forces

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Toeplitz Operators and Carleson Measures for Weighted Bergman Spaces Induced by Regular Weights

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Acta Mathematica Sinica,English Series 2024年第5期40卷 1345-1359页

作者： Jun Tao DU song xiao Hasi WULAN Department of Mathematics Guangdong University of Petrochemical TechnologyMaoming 525000P.R.China Department of Mathematics Shantou UniversityShantou 515063P.R.China

In this paper,we give a universal description of the boundedness and compactness of Toeplitz operator T_(μ)^(ω)between Bergman spaces A_(η)^(p)and A_(υ)^(q)whenμis a positive Borel measure,1 详细信息

In this paper,we give a universal description of the boundedness and compactness of Toeplitz operator T_(μ)^(ω)between Bergman spaces A_(η)^(p)and A_(υ)^(q)whenμis a positive Borel measure,1

关键词： Bergman space Carleson measure Toeplitz operator regular weight

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Data augmentation method for insulators based on Cycle-GAN

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Journal of Electronic Science and Technology 2024年第2期22卷 36-47页

作者： Run Ye Azzedine Boukerche xiao-song Yu Cheng Zhang Bin Yan xiao-Jia Zhou School of Automation Engineering University of Electronic Science and Technology of ChinaChengdu611731China School of Electrical Engineering and Computer Science University of OttawaOttawaK1N6N5Canada Yangtze River Delta Research Institute(Huzhou) University of Electronic Science and Technology of ChinaHuzhou313001China

Data augmentation is an important task of using existing data to expand data *** generative countermeasure network technology to realize data augmentation has the advantages of high-quality generated samples,simple training,and fewer restrictions on the number of generated ***,in the field of transmission line insulator images,the freely synthesized samples are prone to produce fuzzy backgrounds and disordered samples of the main insulator *** solve the above problems,this paper uses the cycle generative adversarial network(Cycle-GAN)used for domain conversion in the generation countermeasure network as the initial framework and uses the self-attention mechanism and channel attention mechanism to assist the conversion to realize the mutual conversion of different insulator *** attention module with prior knowledge is used to build the generation countermeasure network,and the generative adversarial network(GAN)model with local controllable generation is built to realize the directional generation of insulator belt defect *** experimental results show that the samples obtained by this method are improved in a number of quality indicators,and the quality effect of the samples obtained is excellent,which has a reference value for the data expansion of insulator images.

关键词： Data expansion Deep learning Generate confrontation network Insulator

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Effect of Ti contents on interfacial bonding, mechanical and thermal properties of Mo-Cu composites

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Tungsten 2024年第3期6卷 549-554页

作者： Jian-Ru Chu xiao-song Jiang Tian-Yan Liu Key Laboratory of Advanced Technologies of Materials Ministry of Education School of Materials Science and Engineering Southwest Jiaotong University Reactor Engineering Research Sub-Institute Nuclear Power Institute of China

Mo-Cu composites are widely used in electronic packaging, vacuum technology, microwave devices and other fields due to their excellent properties, such as excellent electrical and thermal conductivity, low adjustable ...

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Characteristics of perfluoromethyl vinyl ether: A new eco-friendly alternative gas for SF6

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HIGH VOLTAGE 2024年第3期9卷 509-517页

作者： xiao, song Chen, Yijiang Tang, Mingjun Tian, Shuangshuang Xia, Haoran Wang, Yifan Li, Yi Zhang, xiaoxing Wuhan Univ Sch Elect Engn & Automat State Key Lab Power Grid Environm Protect Wuhan Peoples R China Hubei Univ Technol Sch Elect & Elect Engn Key Lab High Efficiency Utilizat Solar Energy & Op Wuhan Peoples R China

The exploration of eco-friendly insulating gas to substitute the most potent greenhouse gas sulphur hexafluoride (SF6) has consistently garnered significant attention. Herein, the authors evaluated the feasibility of utilising perfluoromethyl vinyl ether (PMVE, C3F6O) as a new branch of eco-friendly insulating gas for the first time. The primary dielectric and stability characteristics of PMVE regarding AC breakdown, partial discharge, dielectric recovery, and decomposition properties were revealed under various gas pressure and electrical field conditions. It was found that PMVE demonstrated superior dielectric strength, with the AC breakdown and PD inception voltage (PDIV) 1.10 and 1.14 times that of pure SF6. Furthermore, the dielectric strength of PMVE exhibits stability even after undergoing 100 cycles of AC breakdowns, and there is no observable formation of solid precipitation on the electrode surface. The discharge decomposition of PMVE mainly generates fluorocarbon (CF4, C2F6, C3F6, C3F8, etc.) and CO. Overall, the exceptional insulation stability and no absence of solid precipitation features endow PMVE to be utilised as a new eco-friendly gas for SF6-free gas-insulated equipment.

关键词： INSULATION REPLACE

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Mechanism of Ta on the microstructure and properties of Fe-Mn damping alloys

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Tungsten 2024年第4期6卷 767-777页

作者： Gui-Xiang Liu Kun Zhang Chao Han xiao-Lin Shao Jun Lu Lin Zhang xiao-song Jiang Zi-Xuan Wu Liu Yang The Second Sub-Institute Nuclear Power Institute of China Key Laboratory of Advanced Technologies of Materials Ministry of Education School of Materials Science and Engineering Southwest Jiao tong University School of Engineering and Materials Science Queen Mary University of London Institute for Applied Materials (IAM-WK) Karlsruhe Institute of Technology (KIT)

Fe-Mn-Co-xTa alloys（x=0,1,2,3 wt.%） were fabricated using spark plasma sintering to explore the influence of Ta content on the microstructure,mechanical properties,and damping characteristics of Fe-17Mn-3Co damping *** micro structural analysis reveals the dominant presence of γ-austenite,ε-martensite,α'-martensite,and Co3Ta precipitates within the *** increments in Ta content exhibit proportional enhancements in hardness,tensile strength,and fracture elongation of the ***,these improvements in mechanical attributes are closely correlated with the generated second-phase *** the Ta content increases,there is a gradual augmentation in the formation of Co3Ta within the ***,the damping property initially experiences an ascent followed by a subsequent decline with rising Ta *** damping behavior finds its origins in multiple mechanisms,including grain boundary damping stemming from reduced grain size,interfacial damping induced by the generated Co3Ta,and dislocation *** is noteworthy that the emergence of the secondary phase wields a dual impact on damping *** the one hand,the proliferation of the second phase fosters increased interfaces for energy *** the other hand,these interfaces give rise to compressive stresses,constraining interface movement and thus impeding damping property enhancement.

关键词： Damping Fe–Mn–Co Mechanical properties Spark plasma sintering Ta

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Assessment on gas-polyethylene terephthalate solid interface partial discharge properties of C4F7N/CO_(2)gas mixture for eco-friendly gas insulating transformer

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High Voltage 2024年第1期9卷 35-45页

作者： song xiao Yifan Wang Chenhua Ren Haoran Xia Yue Zhao Jingzi Qin xiaoxing Zhang Yi Luo Yi Li State Key Laboratory of Power Grid Environmental Protection School of Electrical Engineering and AutomationWuhan UniversityWuhanHubeiChina Beijing International S&T Cooperation Base for Plasma Science and Energy Conversion Institute of Electrical EngineeringChinese Academy of SciencesBeijingChina State Grid Anhui Electric Power Company Anhui Electric Power Research Institute HefeiAnhuiChina Hubei Engineering Research Center for Safety Monitoring of New Energy and Power Grid Equipment School of Electrical and Electronic EngineeringHubei University of TechnologyWuhanHubeiChina

The eco-friendly insulating gas perfluoroisobutyronitrile(C_(4)F_(7)N)is potentially used in gas-insulated transformers(GIT)to replace sulphur hexafluoride(SF_(6)).However,evaluation of the long-term insulation reliability and gas–solid interface discharge decomposition characteristics of the gas–solid film insulation structure in GIT is *** authors simulated the gas–solid film insulation structure in GIT and explored the interface partial discharge(PD)characteristics of C4F7N/CO_(2)gas mixture with polyethylene terephthalate(PET).The effect of gas pressure,mixing ratio on gas–solid interface gas decomposition,PET degradation was investigated,and the interaction mechanism was *** is found that the interface PD generated three degradation regions on a PET *** gas–solid interface reaction in the electrode contact region and the discharge development trace was significantly higher than that of halation *** content of gas decomposition products decreases with the increase of gas pressure and the PD intensity of SF6-PET is inferior to that of C_(4)F_(7)N/CO_(2)under the same *** results provide reference for the development and application of C_(4)F_(7)N/CO_(2)based GIT.

关键词： interface solid insulation

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Decoding the inconsistency of six cropland maps in China

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The Crop Journal 2024年第1期12卷 281-294页

作者： Yifeng Cui Ronggao Liu Zhichao Li Chao Zhang xiao-Peng song Jilin Yang Le Yu Mengxi Chen Jinwei Dong Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Department of Geographical Sciences University of MarylandCollege ParkMD 20740USA College of Grassland Science and Technology China Agricultural UniversityBeijing 100193China Ministry of Education Ecological Field Station for East Asian Migratory Birds Department of Earth System ScienceInstitute for Global Change StudiesTsinghua UniversityBeijing 100084China Ministry of Education Ecological Field Station for East Asian Migratory Birds Beijing 100084China Tsinghua University(Department of Earth System Science)-Xi’an Institute of Surveying and Mapping Joint Research Center for Next-Generation Smart Mapping Beijing 100084China Institute of Remote Sensing and Geographic Information System Peking UniversityBeijing 100871China Department of Forest and Conservation Sciences University of British ColumbiaVancouverBCV6T 1Z4Canada

Accurate cropland information is critical for agricultural planning and production,especially in foodstressed countries like *** widely used medium-to-high-resolution satellite-based cropland maps have been developed from various remotely sensed data sources over the past few decades,considerable discrepancies exist among these products both in total area and in spatial distribution of croplands,impeding further applications of these *** factors influencing their inconsistency are also *** this study,we evaluated the consistency and accuracy of six cropland maps widely used in China in circa 2020,including three state-of-the-art 10-m products(i.e.,Google Dynamic World,ESRI Land Cover,and ESA WorldCover)and three 30-m ones(i.e.,GLC_FCS30,GlobeLand 30,and CLCD).We also investigated the effects of landscape fragmentation,climate,and agricultural *** using a ground-truth sample revealed that the 10-m-resolution WorldCover provided the highest accuracy(92.3%).These maps collectively overestimated Chinese cropland area by up to 56%.Up to 37%of the land showed spatial inconsistency among the maps,concentrated mainly in mountainous regions and attributed to the varying accuracy of cropland maps,cropland fragmentation and management practices such as *** work shed light on the promotion of future cropland mapping efforts,especially in highly inconsistent regions.

关键词： Consistency and accuracy 10-and 30 m Cropland mapping Agricultural management China

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Effect of SARS-CoV-2 infection on semen parameters in sperm bank volunteers with normal sperm concentration

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Asian Journal of Andrology 2024年第3期26卷 328-332页

作者： Li Wang Wen-Kai Han xiao-Hui song Qi-Lin Zhang An-Quan Guan Yuan Gao Jin-Long Ma Center for Reproductive Medicine Shandong UniversityJinan 250001China State Key Laboratory of Reproductive Medicine and Offspring Health ShandongUniversityJinan 250001China Key Laboratory of Reproductive Endocrinology of Ministry of Education Shandong UniversityJinan 250001China Shandong KeyLaboratory of Reproductive Medicine Shandong Provincial Hospital Affiliated to Shandong First Medical UniversityJinan 250001China Shandong Provincial Clinical Research Center for Reproductive Health Jinan 250001China Shandong Technology Innovation Center for Reproductive Health Jinan 250001China NationalResearch Center for Assisted Reproductive Technology and Reproductive Genetics Shandong UniversityJinan 250001China Research Unit of Gametogenesis andHealth of ART-Offspring Chinese Academy of Medical Sciences(No.2021RU001)Jinan 250001China

In this study,we aimed to assess the effect of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection on *** study comprised 110 sperm volunteers who self-reported SARS-CoV-2 infection from the Human Sperm Bank ofthe Center for Reproductive Medicine,Shandong University(Jinan,China).The volunteers had normal sperm concentration *** volunteer provided semen samples before and after *** selected 90 days after infection as the cutoff *** parameters within 90 days after infection of 109 volunteers(group A)were compared with semen parameters before ***,semen parameters on or after 90 days after infection of 36 volunteers(group B)were compared with semen parameters ***,based on whether the volunteers had completed the three-dose SARS-CoV-2 vaccination booster,volunteersin group A and B were further divided into two subgroups *** parameters were compared before and after infection ineach *** results showed that in this cohort population,the semen quality in volunteers with normal sperm concentrationsbefore infection decreased after SARS-CoV-2 infection within 90 days,while the semen quality returned to preinfection levels after *** completion of a three-dose SARS-CoV-2 vaccination booster may exert a protective effect on semen quality after infection.

关键词： SARS-CoV-2 SARS-CoV-2 vaccination semen quality sperm donation sperm parameters

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Postoperative abdominal herpes zoster complicated by intestinal obstruction:A case report

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World Journal of Clinical Cases 2024年第6期12卷 1138-1143页

作者： Zhen-Yu Dong Rui-Xian Shi xiao-Biao song Ming-Yue Du Ji-Jun Wang Department of General Surgery Baotou Central HospitalBaotou 014040Inner Mongolia Autonomous RegionChina Department of General Surgery Baotou Medical CollegeBaotou 014040Inner Mongolia Autonomous RegionChina Department of Neurology Baotou Central HospitalBaotou 014040Inner Mongolia Autonomous RegionChina Department of Neurology Inner Mongolia Medical UniversityHohhot 010110Inner Mongolia Autonomous RegionChina

BACKGROUND Intestinal obstruction is a common occurrence in clinical ***,the occurrence of herpes zoster complicated by intestinal obstruction after abdominal surgery is exceedingly *** the diagnostic and treatment process,clinicians consider it crucial to identify the primary causes of its occurrence to ensure effective treatment and avoiding *** SUMMARY Herein,we present the case of a 40-year-old female patient with intestinal obstruction who underwent laparoscopic appendectomy and developed herpes zoster after *** the patient's clinical manifestations and relevant laboratory tests,it was suggested that the varicella zoster virus reactivated during the latent period after abdominal surgery,causing herpes ***,the herpes virus invaded the visceral nerve fibers,causing gastrointestinal dysfunction and loss of intestinal peristalsis,which eventually led to intestinal *** patient was successfully treated through conservative treatment and antiviral therapy and subsequently discharged from the *** Pseudo-intestinal obstruction secondary to herpes zoster infection is difficult to distinguish from mechanical intestinal obstruction owing to various *** cases of inexplicable intestinal obstructions,considering the possibility of a viral infection is essential to minimize misdiagnosis and missed diagnoses。

关键词： Herpes zoster Pseudo-intestinal obstruction Ogilvie syndrome Peripheral motor neuropathy Case report

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