检索结果-南通市图书馆

Construction of three-dimensional hierarchical porous nitrogen-doped re duce d graphene oxide/hollow cobalt ferrite composite aerogels toward highly efficient electromagnetic wave absorption

引用

journal of Materials Science & Technology 2023年第1期132卷 193-200页

作者： jing Xu Ruiwen Shu Zongli wan j.anjun Shi State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan 232001China School of Chemical Engineering Anhui University of Science and TechnologyHuainan 232001China Institute of Environment-Friendly Materials and Occupational Health Anhui University of Science and TechnologyWuhu 241003China

The development of graphene-based composites with low density,robust absorption,wide bandwidth and thin thickness remained a great challenge in the field of electromagnetic(EM)*** this work,nitrogen-doped reduced graphene oxide/hollow cobalt ferrite(NRGO/hollow CoFe_(2)O_(4))composite aerogels were constructed by a solvothermal and hydrothermal two-step *** demonstrated that the as-fabricated composite aerogels had the ultralow density and a unique three-dimensional(3D)network structure,and lots of hollow CoFe_(2)O_(4)microspheres were almost homogeneously distributed on the wrinkled surfaces of lamellar ***,superior EM absorbing capacity could be achieved by modulating the ferrite structure,addition amounts of hollow CoFe_(2)O_(4)and *** was noteworthy that the NRGO/hollow CoFe_(2)O_(4)composite aerogel with the addition amount of ferrite of 15.0 mg pos-sessed the minimum reflection loss of-44.7 dB and maximum absorption bandwidth of 5.2 GHz(from 12.6 to 17.8 GHz)at a very thin thickness of 1.8 mm and filling ratio of 15.0 wt.%.Furthermore,the possible EM attenuation mechanism had been *** results of this work would be helpful for developing RGO-based 3D composites as lightweight,thin and highly efficient EM wave absorbers.

关键词： Graphene Composite aerogels Hollow ferrite Three-dimensional network Nitrogen doping

来源：

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

Elucidating the structure-activity relationship of Cu-Ag bimetallic catalysts for electrochemical CO_(2) reduction

引用

journal of Energy Chemistry 2024年第6期93卷 345-351,I0009页

作者： Qining Huang Lili wan Qingxuan Ren jingshan Luo Institute of Photoelectronic Thin Film Devices and Technology State Key Laboratory of Photovoltaic Materials and CellsKey Laboratory of Photoelectronic Thin Film Devices and Technology of TianjinMinistry of Education Engineering Research Center of Thin Film Photoelectronic TechnologyNankai UniversityTianjin 300350China Frontiers Science Center for New Organic Matter Nankai UniversityTianjin 300071China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Developing bimetallic catalysts is an effective strategy for enhancing the activity and selectivity of electrochemical CO_(2) reduction reactions,where understanding the structure-activity relationship is essential for catalyst ***,we prepared two Cu-Ag bimetallic catalysts with Ag nanoparticles attached to the top or the bottom of Cu *** tested in a flow cell,the Cu-Ag catalyst with Ag nanoparticles on the bottom achieved a faradaic efficiency of 54%for ethylene production,much higher than the catalyst with Ag nanoparticles on the *** catalysts were further studied in the H-cell and zero-gap MEA *** was found that placing the two metals in the intensified reaction zone is crucial to triggering the tandem reaction of bimetallic *** work elucidates the structure-activity relationship of bimetallic catalysts for CO_(2) reduction and demonstrates the importance of considering both catalyst structures and cell characteristics to achieve high activity and selectivity.

关键词： Electrochemical CO_(2)reduction Bimetallic catalyst Cu-Ag Structure-activity relationship

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A New Foraminiferal Bioindicator for Long-Term Heat Stress on Coral Reefs

引用

journal of Earth Science 2022年第6期33卷 1451-1459页

作者： Alexander F.Humphreys Sam j.Purkis Chuyan wan Matthew Aldrich Sarah Nichols jazmin Garza Rosenstiel School of Marine and Atmospheric Science Department of Marine GeosciencesUniversity of MiamiMiamiFL33149USA Khaled bin Sultan Living Oceans Foundation AnnapolisMD21403USA Department of Earth and Planetary Sciences Northwestern UniversityEvanstonIL60208USA

Coral reefs are in terminal *** conservation to be effective,naturally depauperate reefs must be distinguished from those recently degraded by *** reef monitoring is time consuming and lacks the longevity to make this *** in using foraminifera as bioindicators for reef health has hitherto levered their response to *** ocean heat waves are the dominant driver of coral bleaching and death,there is compelling motivation to develop new foraminiferal bioindicators that inform on temperature stress over meaningful *** study focuses on identifying which foraminifera respond systematically to the temperature stress that kills *** models were used to compare endosymbiont-bearing foraminiferal families,collected along a heat-stress gradient spanning the Solomon Islands and New Caledonia,to live coral cover at the same *** indicate that Amphisteginidae foraminifera and coral cover show a significant decline in abundance as heat stress increases along the transect ***,ocean productivity and salinity,both recognized environmental influences on foraminifera,are shown to be subordinate to temperature in their sway of this ecological *** findings indicate the potential for using foraminifera to develop new indices capable of quantifying long-term thermal impacts on reefs.

关键词： foraminifera bioindicator corals bleaching degree heating week FoRAM Index

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Numerical study of vibrations of a vertical tension riser excited at the top end

引用

journal of Ocean Engineering and Science 2017年第4期2卷 268-278页

作者： Bowen Fu Decheng wan State Key Laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityCollaborative Innovation Center for Advanced Ship and Deep-Sea ExplorationShanghai 200240China

This paper presents numerical simulations of vortex-induced vibrations of a vertical riser which is sinusoidally excited at its top end in both one and two directions in still water.A computational fluid dynamics method based on the strip theory is *** riser’s responses to both top-end and two-end excitations are carefully *** low reduced velocity cases,the in-line vibrations consist of three components,the low-frequency oscillation,the first-natural-frequency vibration during the riser reversal,and the second-natural-frequency vibration due to vortex *** sheared oscillatory flow along the span causes low-frequency oscillations in higher modes in the in-line direction,thus forming‘X’shaped,‘II’shaped,and‘O’shaped trajectories at various positions along the span when the riser is excited at its top end in one *** the presence of excitations in the other direction,more complex trajectories appear.

关键词： Vortex-induced vibration Oscillatory flow Riser Platform motion Viv-FOAM-SjTU solver

来源：

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

AgBF_4/[emim][BF_4] supported ionic liquid membrane for carbon monoxide/nitrogen separation

引用

journal of Energy Chemistry 2019年第2期28卷 31-39页

作者： Shichao Feng Yuanyuan Wu j.anquan Luo Yinhua wan State Key Laboratory of Biochemical Engineering Institute of Process EngineeringChinese Academy of Sciences

In this paper,AgBF_4/[emim][BF_4] supported ionic liquid membranes(SILMs) were prepared successfully for CO/N_2 separation using nitrogen pressure immobilization *** incorporation of AgBF_4 could decrease membrane weight loss,improve the pressure-resistant ability,and keep the critical pressure(0.45 MPa) of the *** high viscosity and undissolved Ag BF_4 solids in membrane liquid would disturb gas molecular transport through membrane and give rise to the gas transport ***,the gas permeability decreased remarkably with increasing AgBF_4 carrier content in the *** the molar ratio of AgBF_4 to [emim][BF_4] increased from 0:1 to 0.3:1,the CO/N_2 selectivity of the SILMs showed a great increase from ～1 to ～9 at 20 °C and 0.4 MPa,suggesting that AgBF_4 was an effective carrier for CO facilitated *** permeabilities of N_2 and CO increased at higher transmembrane pressure,indicating that molecular transport would dominate the transport process at high *** temperature-dependent gas permeability followed the Arrhenius ***,the differences between the activation energies of CO and N_2 became larger after introducing AgBF_4,resulting in more obvious decrease in the CO/N_2 selectivity at higher operating temperature.

关键词： Supported ionic liquid membranes [emim][BF4] AgBF4 Carbon monoxide separation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Multiple model predictive control of perching maneuver based on guardian maps

引用

Chinese journal of Aeronautics 2022年第5期35卷 347-360页

作者： Rui CAO Huiwen wan Zhen HE Yuping LU College of Automated Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Considering the strong nonlinearity of Unmanned Aerial Vehicles(UAVs)resulting from high Angle of Attack(AOA)and fast maneuvering,we present a multi-model predictive control strategy for UAV maneuvering,which has a small amount of online ***,we divide the maneuver envelope of UAV into several sub-regions on the basis of the gap metric theory.A novel algorithm is then developed to determine the ploytopic model for each *** to this,a Robust Model Predictive Control based on the Idea of Comprehensive optimization(ICE-RMPC)is *** control law is designed offline and optimized online to reduce the computational ***,the ICE-RMPC method is applied to design the controllers of *** addition,to guarantee the stability of whole closed-loop system,a multi-model switching control strategy based on guardian maps is put ***,the tracking performance of proposed control strategy is demonstrated by an illustrative example.

关键词： Guardian maps Model predictive control Multi-Model switching rule Online comprehensive design Perching maneuver

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Numerical investigation of the factors influencing the vertical profiles of current,salinity,and SSC within a turbidity maximum zone

引用

International journal of Sediment Research 2017年第1期32卷 20-33页

作者： Yuanyang wan Li wang Shanghai Estuarine and Coastal Science Research Center International Marine and Dredging Consultants

The flow-sediment interaction plays a considerable role on the vertical(internal) profiles of current,salinity and suspended sediment concentration(SSC) within a turbidity maximum zone(TMZ).Numerical modeling provides valuable insights into the complex estuarine physical *** combining numerical modeling with field observations,the influencing factors of fine sediment dynamics within the TMZ of Yangtze Estuary have been explored in this ***,during the neap tide,the measured data present that the current is too weak to break the density stratification,and the vertical flow structure is effectively ***,a three-dimensional numerical model based on the Delft3 D has been developed and a range of numerical sensitivity analyses were carried out to distinguish the dominant mechanisms and physical processes responsible for the phenomena observed from the measurement *** numerical investigation highlights the following findings.(1) The vertical profile of currents within the TMZ is largely affected by saltwater intrusion,especially during lower currents when the baroclinic pressure gradient can significantly reshape the local vertical profiles of velocity.(2) The baroclinic effects are primarily determined by the stratification of salinity.(3) In addition to salinity,SSC also influences the local density stratification when its contribution to fluid density is comparable to that of salinity.(4) The settling velocity determines the overall sediment distribution and vertical profiles of the SSC in the water *** SSC-dependent settling velocity(including the flocculation-induced acceleration and hindered settling deceleration phases) affects the longitudinal movement of the sediments.(5) The vertical profiles of current,salinity and SSC within the TMZ are highly associated with the turbulence determined by the *** approach to modulate the vertical eddy viscosity in the model,based on the empirical dependency between Rigand Prt,may

关键词： Turbidity maximum zone(TMZ) Fine sediment Residual circulation Yangtze Estuary Modelling Tidal asymmetry Stratification Turbulence Salinity

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Inconsistent interspecific and intraspecific differentiation of climate envelopes in a subtropical tree

引用

journal of Plant Ecology 2019年第1期12卷 176-185页

作者： Qiuchi wan Zhuo Zheng Marta Benito-Garzón Rémy j.Petit School of Earth Science and Geological Engineering Sun Yat-sen University135 Xingang RoadHaizhu DistrictGuangzhou 510275China Biogeco INRAUniversity of Bordeaux69 Arcachon Road33610 CestasFrance

Aims Comparisons of climate envelopes among species have shown that niche conservatism tends to break down over ***,we use the Asian tree genus Platycarya(juglandaceae)as a case study to test this tendency at relatively short timescales in a single ***,together with a reanalysis of the extant literature,should help evaluate prospects of using correlations between climate and spe-cies occurrence data to infer evolutionary *** We rely on species distribution models(SDMs)and multivari-ate analyses to compare current and past(Last Glacial Maximum~21ka)climatic envelopes between the two extant Platycarya spe-cies(Platycarya strobilacea and Platycarya longipes)and between mainland and Taiwan populations of ***,paying particu-lar attention to autocorrelation *** also review interpreta-tions provided in similar studies comparing climate envelopes between and within species,including in studies involving native and introduced populations of the same *** Findings We find intraspecific but not interspecific differentiation in climate envelopes of Platycarya,despite the prediction that niche differen-tiation should be stronger between older *** review also suggests that differentiation in climate envelopes need not imply rapid evolutionary *** SDMs can be used to raise evolutionary hypotheses to be validated with other data,we con-clude that it should not be used to directly infer short-term evolu-tionary processes.

关键词： climate envelope Last Glacial Maximum evolution Platycarya species distribution models

来源：

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

Mesozoic-Cenozoic Tectonics of the Yellow Sea and Oil-Gas Exploration

引用

Acta Geologica Sinica(English Edition) 2010年第1期84卷 77-90页

作者： wan Tianfeng HAO Tianyao China University of Geosciences Beijing 100083 China Institute of Geology and Geophysics the Chinese Academy of Sciences Beijing 100101 China

The purpose of the present study was to study the tectonics of the Yellow Sea. Although oilgas exploration has been undertaken for more than 30 years in the southern Yellow Sea, the exploration progress has achieved little. There are three tectonic periods with near N-S trending shortening and compression （260-200 Ma, 135-52 Ma and 23-0.78 Ma） and three tectonic periods with near E-W trending shortening and compression （200-135 Ma, 52--23 Ma and 0.78 Ma） at the Yellow Sea and adjacent areas during the Mesozoic and Cenozoic. The lndosinian tectonic period is the collision period between the Sino-Korean and Yangtze Plates, which formed the basic tectonic framework for the Yellow Sea area. There were strong intraplate deformations during the Yanshanian （200-135 Ma） and Sichuanian （135-52 Ma） periods with different tectonic models, which are also the main formation periods for endogenic metallic mineral deposits around the Yellow Sea. The three tectonic periods during the Cenozoic affect important influences for forming oil-gas reservoirs. The Eocene-Oligocene （52-23 Ma） is the main forming period for oil-gas sources. The Miocene-Early Pleistocene （23-0.78 Ma） was a period of favorable passage for oil-gas migration along NNE trending faults. Since the Middle Pleistocene （0.78 Ma） the NNE trending faults are closed and make good conditions for the reservation of oil-gas. The authors suggest that we pay more attention to the oil-gas exploration at the intersections between the NNE trending existing faults and Paleogene- Neogene systems in the southern Yellow Sea area.

关键词： tectonics stress field oil-gas exploration Mesozoic-Cenozoic Yellow Sea

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Microstructure evolution and mechanical properties of brazing joint for ultra-thin-walled Inconel 718 considering grain size effect and brazing temperature

引用

Chinese journal of Aeronautics 2024年第2期37卷 541-556页

作者： Rui ZHAO Yueshuai SONG Hui KANG Min wan School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China j.angxi Research Institute of Beihang University Jiangxi 330000China

The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high demands on its *** achieve this objective,this study investigates the impact of three distinct brazing temperatures and five typical grain sizes on the brazed joints’mechanical properties and microstructure evolution *** evolution analysis was conducted based on Electron Back Scatter Diffraction(EBSD),Scanning Electron Microscopy(SEM),X-Ray Diffraction(XRD),High-Resolution Transmission Electron Microscopy(HRTEM),and Focused Ion Beam(FIB).Besides,the mechanical properties and fracture behavior were studied based on the uniaxial tension tests and in-situ tension *** findings reveal that the brazing joint’s strength is higher for the fine-grain capillary than the coarse-grain one,primarily due to the formation of a dense branch structure composed of G-phase in the brazing *** effects of grain size,such as pinning and splitting,are amplified at higher brazing ***,micro-cracks initiate around brittle intermetallic compounds and propagate through the eutectic zone,leading to a cleavage fracture *** fracture stress of fine-grain specimens is higher than that of coarse-grain due to the complex micro-crack ***,this study contributes significantly to the literature by highlighting the crucial impact of grain size on the brazing properties of ultra-thin-walled Inconel 718 structures.

关键词： EYWORDS Ultra-thin-walled structure Brazing Inconel 718 Grain size effect Brazing temperature

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：