检索结果-南通市图书馆

research on Cavitation Characteristics and Influencing Factors of Herringbone Gear pump

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第6期139卷 2917-2946页

作者： Jinlong Yang Kwang-Hee lee Chul-Hee lee Department of Mechanical Engineering of Inha University Incheon22212South Korea

Cavitation is a common issue in pumps,causing a decrease in pump head,a fall in volumetric efficiency,and an intensification of outlet flow *** is one of the main hazards that affect the regular operation of the *** on pump cavitation mainly focuses on mixed flow pumps,jet pumps,external spur gear pumps,***,there are few cavitation studies on external herringbone gear *** addition,pumps with different working principles significantly differ in the flow and complexity of the internal flow ***,it is urgent to study the cavitation characteristics of external herringbone gear *** with experimentalmethods,visual research and cavitation area identification are achieved through computation fluid dynamic(CFD),and changing the boundary conditions and shape of the gear rotor is *** simulation yields a head error of only 0.003%under different grid numbers,and the deviation between experimental and simulation results is less than 5%.The study revealed that cavitation causes flow pulsation at the outlet,and the cavitation serious area is mainly distributed in the meshing gap and meshing *** can be inhibited by reducing the speed,increasing the inlet pressure,and changing the helix angle can be *** example,when the inlet pressure is 5 bar,the maximumgas volume fraction in themeshing area is less than 50%.These results provide a reference for optimizing the design and finding the optimal design parameters to reduce or eliminate cavitation.

关键词： Herringbone gear pump cavitation rotating speed inlet pressure helix angle TwinMesh

Strengthening mechanisms analysis and tailoring of bimodal grain structures for enhanced strength in CoCrFeMnNi high-entropy alloys

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

rare Metals 2024年第8期43卷 3893-3903页

作者： Jaesoung lee Seulgi Kim Taehyun Kwon Young II Kim Suyeon Kim Sung Ho Song Bin lee Dongju lee Department of Urban Energyand Environmental Engineering Chungbuk National University Division of Advanced Materials Engineering Kongju National University Department of Advanced Materials Engineering for Information and Electronics Integrated-Education Institute for Frontier Science and Technology (BK21 Four)Kyung Hee University

The CoCrFeMnNi high-entropy alloys(HEAs)with a(face-centered cubic) FCC structure has garnered considerable attention for its exceptional ductility and strain hardening ***,its yield strength is insufficient for structural *** this study,strengthening mechanisms in these HEAs were investigated to gain insight into the mechanical properties according to alloy powder ***,we present a novel approach to achieve both high strength and high ductility through the creation of a bimodal structure consisting of both coarse and fine grains via gas atomization and spark plasma sintering processes.A bimodally structured HEA prepared with a mass ratio of 2:8 between coarse particles(75-106 μm) and fine particles(≤25 μm)yielded optimal results,with a strength of 491.95 Mpa and elongation of 19.64%.This strength value represents an～41% increase compared with the sample that displayed a fine single microstructure(347.08 Mpa for yield strength).The strength enhancement was attributed to the prevention of plastic deformation initiation from the fine particles during *** innovative approach to the creation of HEAs with bimodal structures shows promise for various applications,such as structural components that require a combination of high strength and high ductility.

关键词： High-entropy alloys CrCoFeMoNi Bimodal Gas atomization Mechanical properties

production of chitosan-based composite film reinforced with lignin-rich lignocellulose nanofibers from rice husk

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Bioresources and Bioproducts 2024年第2期9卷 174-184页

作者： Hye Jee Kang Yeon Ju lee Jin Kyoung lee Irnia Nurika Sri Suhartini Deokyeong Choe Dong Hyun Kim Hoon Choi Natasha p.Murphy Ho Yong Kim Young Hoon Jung School of Food Science and Biotechnology Kyungpook National UniversityDaegu 41566Republic of Korea Cpr S&T Co. Ltd.Gunpo 15880Republic of Korea Department of Agroindustrial Technology Faculty of Agricultural TechnologyUniversitas BrawijayaMalang 65145Indonesia renewable resources and Enabling Sciences Center National Renewable Energy LaboratoryGoldenCO 80401United States Center for Bio-based Chemistry Korea Research Institute of Chemical TechnologyUlsan 44429Republic of Korea

Lignocellulosic nanofibers(LCNFs),implying lignin-containing cellulose fibers,maintain the prop-erties of both lignin and cellulose,which are hydrophobic and hydrophilic,*** pres-ence of hydrophobic lignin in LCNFs is expected to be an economical and attractive option that can improve the thermal and mechanical properties of ***,this study was conducted to produce lignin-rich LCNFs from sugar-rich waste obtained from rice husks after acidic *** LCNFs were produced from the lignin-rich solid fractions obtained after pretreatment and enzymatic hydrolysis,which were then incorporated as an additive into a chitosan-based *** variations in lignin content in the range of approximately 50.6%-66.8%in differently obtained LCNFs gave significantly different optical strengths and mechanical *** controllable processes may allow for customized film ***,the glucose-rich liquid fractions obtained after pretreatment and enzymatic hydrolysis were used as a substrate for ethanol fermentation to achieve total utilization of rice husk biomass *** conclusion,the lignin-rich biomass fraction holds promise as a suitable material for chitosan-LCNF film and has the potential to increase the economic feasibility of the biomaterial industry.

关键词： rice husk Lignocellulose nanofiber Lignin-based material Chitosan film Upcycling

Development of vehicle-recognition method on water surfaces using LiDAr data:SpD^(2)(spherically stratified point projection with diameter and distance)

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第6期36卷 95-104页

作者： Eon-ho lee Hyeon Jun Jeon Jinwoo Choi Hyun-Taek Choi Sejin lee The Department of Mechanical Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea Ocean System Engineering research Division Korea Research Institute of Ships and Ocean Engineering(KRISO)Daejeon 34103Republic of Korea The Division of Mechanical&Automotive Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea

Swarm robot systems are an important application of autonomous unmanned surface vehicles on water *** monitoring natural environments and conducting security activities within a certain range using a surface vehicle,the swarm robot system is more efficient than the operation of a single object as the former can reduce cost and save *** is necessary to detect adjacent surface obstacles robustly to operate a cluster of unmanned surface *** this purpose,a LiDAr(light detection and ranging)sensor is used as it can simultaneously obtain 3D information for all directions,relatively robustly and accurately,irrespective of the surrounding environmental *** the GpS(global-positioning-system)error range exists,obtaining measurements of the surface-vessel position can still ensure stability during platoon *** this study,a three-layer convolutional neural network is applied to classify types of surface *** aim of this approach is to redefine the sparse 3D point cloud data as 2D image data with a connotative meaning and subsequently utilize this transformed data for object classification ***,we have proposed a descriptor that converts the 3D point cloud data into 2D image *** use this descriptor effectively,it is necessary to perform a clustering operation that separates the point clouds for each *** developed voxel-based clustering for the point cloud ***,using the descriptor,3D point cloud data can be converted into a 2D feature image,and the converted 2D image is provided as an input value to the *** intend to verify the validity of the proposed 3D point cloud feature descriptor by using experimental data in the ***,we explore the feasibility of real-time object classification within this framework.

关键词： Object classification Clustering 3D point cloud data LiDAr(light detection and ranging) Surface vehicle

revealing the influence of in-situ formed LiCl on garnet/Li interface for dendrite-free solid-state batteries

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第5期92卷 394-403页

作者： Seoyoon Shin Jinuk lee Tae Ho Shin Seokhee lee Hydrogen Energy Materials Center Korea Institute of Ceramic Engineering&TechnologyJinju-siGyeongsangnam-do 52851Republic of Korea Department of Materials Science and Engineering Yonsei UniversitySeoul 03722Republic of Korea

Inadequate interfacial contact between lithium and solid-state electrolytes(SSEs)leads to elevated impedance and the growth of lithium dendrites,presenting significant obstacles to the practical viability of solid-state batteries(SSBs).To ameliorate interfacial contact,optimizing the surface treatment of SSEs has been widely ***,the formation of LiCl through acid treatment,an equally crucial factor impacting SSB performance,has received limited attention,leaving its underlying mechanism *** study aims to shed light on SSE characteristics following LiCl formation and the removal of Li_(2)CO_(3) through acid *** seek to establish quantifiable links between SSE surface structure and SSB performance,focusing on interfacial resistance,current distribution,critical current density(CCD),and lithium *** formation of LiCl,occurring as Li_(2)CO_(3) is removed through acid treatment,effectively mitigates lithium dendrite formation on SSE *** action inhibits electron injection and reduces the diffusion rate of Li ***,acid treatment transforms the SSE surface into a lithiophilic state by eliminating surface Li_(2)CO_(3).Consequently,the interfacial resistance between lithium and SSEs substantially decreases from 487.67 to 35.99Ωcm^(2) at 25°*** leads to a notably high CCD of 1.3 mA cm^(-2) and a significantly extended cycle life of 1,000 ***,in full SSBs incorporating LiCoO_(2)cathodes and acid-treated garnet SSEs,we observe exceptional cyclability and rate *** findings highlight that acid treatment not only establishes a fundamental relationship between SSE surfaces and battery performance but also offers an effective strategy for addressing interfacial challenges in SSBs.

关键词： Solid-statebatteries Acidtreatment Interfacial stability LiCl Surface modification

Stability Analysis of DC Microgrid Clusters Based on Step-by-step System Matrix Building Algorithm

在线全文

学校读者我要写书评

暂无评论

Journal of Modern power Systems and Clean Energy 2024年第3期12卷 900-912页

作者： K.Jithin N.Mayadevi r.Hari Kumar V.p.Mini the Department of Electrical Engineering College of Engineering TrivandrumAPJ Abdul Kalam Technological University(APJAKTU)ThiruvananthapuramIndia

DC microgrids(DCMGs)are made up of a network of sources and loads that are connected by a number of power electronic converters(pECs).The increase in the number of these pECs instigates major concerns in system *** interconnecting the microgrids to form a cluster,the system stability must be *** paper proposes a novel stepby-step system matrix building(SMB)algorithm to update the system matrix of an existing DCMG cluster when a new microgrid is added to the cluster through a distribution *** stability of the individual DCMGs and the DCMG cluster is analyzed using the eigenvalue ***,the particle swarm optimization(pSO)algorithm is used to retune the controller gains if the newly formed cluster is not *** simulation of the DCMG cluster is carried out in MATLAB/Simulink environment to test the proposed *** results are also validated using the Op4510 real-time simulator(rTS).

关键词： Converter DC microgrid cluster eigenvalue interconnection particle swarm optimization system stability system matrix

SUMS OF DUAL TOEpLITZ prODUCTS ON THE OrTHOGONAL COMpLEMENTS OF FOCK-SOBOLEV SpACES

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2024年第3期44卷 810-822页

作者：陈泳 Young Joo lee Department of Mathematics Hangzhou Normal UniversityHangzhou311121China Department of Mathematics Chonnam National UniversityGwangju61186Korea

We consider dual Toeplitz operators on the orthogonal complements of the FockSobolev spaces of all nonnegative real ***,for symbols in a certain class containing all bounded functions,we study the problem of when an operator which is finite sums of the dual Toeplitz products is compact or ***,for bounded symbols,we construct a symbol map and exhibit a short exact sequence associated with the C^(*)-algebra generated by all dual Toeplitz operators with bounded symbols.

关键词： dual Toeplitz operators Fock-Sobolev spaces symbol map

Synergistically coupling of Ni–Fe LDH arrays with hollow Co–Mo sulfide nanotriangles for highly efficient overall water splitting

在线全文

学校读者我要写书评

暂无评论

rare Metals 2024年第2期43卷 522-532页

作者： Yun Jae lee Seung-Keun park Department of Advanced Materials Engineering Chung-Ang UniversityAnseongGyeonggi-do17546Republic of Korea Department of Intelligent Energy and Industry Chung-Ang University84 Heukseok-ro Dongjak-guSeoul06974Republic of Korea Western Seoul Center Korea Basic Science Institute150 Bugahyeon-roSeodaemun-guSeoul03759Republic of Korea

Developing bifunctional catalysts that can catalyze both oxygen evolution reaction(OEr)and hydrogen evolution reaction(HEr)is pivotal to commercializing large-scale water ***,a novel hollow nanotriangle composed of NiFe LDH-CoMoS_(x) heterojunction(H-CMSx@NiFe LDH)is proposed as a highly efficient bifunctional electrocatalyst for both OEr and *** fabricate a heterojunction system,ultra-thin nickel–iron layered double hydroxide(NiFe LDH)nanosheets are uniformly electrodeposited onto a metal–organic framework-derived hollow CoMoS_(x) *** strong coupling of CoMoS_(x) and NiFe LDH catalysts forms the intimate heterojunction interfaces to facilitate interfacial charge transfer,which is favorable to enhance the bifunctional catalytic ***,the large void of CoMoS_(x) nanotriangles and interconnected ultra-thin NiFe LDH nanosheets result in good electrolyte penetration and gas ***,the as-prepared H-CMSx@NiFe LDH on nickel foam(NF)exhibits an impressive catalytic activity and durability for OEr and HEr activities,delivering a current density of 100 mA·cm^(−2) at the small overpotentials of 214 and 299 mV in OEr and HEr,***,H-CMSx@NiFe LDH/NF proves to be an effective electrode for an alkaline electrolyzer,as a voltage of only 1.99 V is enough to achieve a current density voltage of only 1.99 V is enough to achieve a current density of 400 mA·cm^(−2) with no degradation in performance over 50 h.

关键词： Overall water splitting Metal-organic framework Molybdenum sulfide Layered double hydroxide Heterojunction

removal of atmospheric methane by soil ecosystems and its controlling variables from microbial to global scales

在线全文

学校读者我要写书评

暂无评论

pedosphere 2024年第1期34卷 15-18页

作者： Hojeong KANG Jaehyun lee School of Civil and Environmental Engineering Yonsei UniversitySeoul 03722Korea

Methane (CH_(4)), a potent greenhouse gas, plays a pivotal role in the dynamics of climate change. While CH_(4) emissions have been widely investigated,biological removal of CH_(4) by upland soils has been less explored. Understanding the mechanisms and factors affecting CH_(4) oxidation in soils is of paramount importance for devising successful mitigation strategies. This perspective paper discusses different types of aerobic methanotrophs and their activities under varying environmental conditions, highlighting the significant contribution of soil ecosystems to global CH_(4) sinks. We emphasize the need for in-depth research on variables controlling CH_(4) sinks on different spatiotemporal scales and the exploration of previously unidentified CH_(4) sinks, such as deserts and areas of glacier retreat.

关键词： soil ecosystems controlling