检索结果-南通市图书馆

When the orbital degree of freedom meets higher-order topology

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2023年第5期12卷 706-707页

作者： Jiazheng Li meng xiao Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education and School of Physics and Technology Wuhan UniversityWuhan 430072China Wuhan Institute of Quantum Technology Wuhan 430206China

The orbital degree of freedom(ODoF),which has a significant impact on exotic quantum states of matter and solidstate materials,has now been combined with higher-order *** experimental realization of a photonic p-orbital higher-order topological insulator can lead to exploring a wide range of novel topological phases involving the ODoF.

关键词： orbital topological topology

Crystallisation regulation of long‐chain branched polypropylene on dielectric performance and energy density for metallised film capacitors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High Voltage 2023年第5期8卷 921-930页

作者： meng xiao mengdie Zhang Boxue Du School of Electrical and Information Engineering Tianjin UniversityTianjinChina

The degradation of dielectric properties of polypropylene(PP)at high temperature affects the operational stability of metallised film *** study presents a method to improve the high‐temperature dielectric performance of PP through long‐chain branching modification and regulating the crystalline *** amounts of nucleating agents were added to long‐chain branched polypropylene(LCBPP)to study the effect of crystallisation on electrical *** results show that the long‐chain branches improve thermal stability by enhancing the chain entanglement,and also increase the number of crystals due to heterogeneous *** addition of nucleating agents promotes the crystallisation of LCBPP,which increases the nucleation density and improves the *** regulation of the microstructure of PP suppresses the relaxation of the chains and limits the charge *** dielectric constant of the modified films with long‐chain branching is slightly increased,and the doping of nucleating agents has little effect on the dielectric constant and loss of *** 125°C,the conductivity of the modified LCBPP films with the addition of 0.05 wt%nucleating agent decreased by 2 orders of magnitude and the breakdown strength increased by 26.3%.This study has implications for improving the dielectric properties of PP films.

关键词： dielectric film performance

Micromorphology and safety properties of meager and meager-lean coal for blast furnace injection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2021年第5期28卷 774-781页

作者： Long-zhe Jin xiao-meng Niu School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China

Four types of meager and meager-lean coal and one type of high-quality anthracite were selected based on the safety requirements for blast furnace coal injection and domestic coal quality to conduct microstructure and component *** analyses of the organic and inorganic macerals and the chemical compositions of the selected coal samples indicate that the four types of meager and meager-lean coal have low volatilization,low ash content,and low sulfur content;these qualities are suitable for blast furnace *** test was conducted on the four types of meager and meager-lean coal and the anthracite mixed coal *** indicate that the mixture of meager and meager-lean coal and anthracite is beneficial to improve the grindability of pulverized *** explosive tests reveal that the selected coal samples are non-explosive or weakly *** the proportion of meager and meager-lean coal is less than 40wt%,the mixed coal powder would not explode during the blowing *** minimum ignition temperature test determines that the minimum ignition temperatures of the four types of meager and meager-lean coal and anthracite are 326,313,310,315,and 393°C,*** study provides a guiding research idea for the safety of meager and meager-lean coal used in blast furnace injection.

关键词： meager coal meager-lean coal microstructure safety property blast furnace injection

Phase evolution of binary immiscible Al-Sn film

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2022年第12期41卷 4241-4247页

作者： xiao-meng Pan Hui-Ping Duan School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Binary immiscible Al-Sn alloy is a very important potential anode material for lithium ion *** phase stability and separation process of Al-Sn film,fabricated by magnetron co-sputtering method,was investigated by X-ray diffractometer(XRD),differential scanning calorimetry(DSC) and in situ transmission electron microscopy(TEM) and explained by Miedema theoretical *** analysis reveals that the asdeposited Al-Sn film will decompose spontaneously into Al-riched areas and Sn-riched areas because of the positive mixing *** crystallization process takes place when the Al content in the Al-riched area or Sn content in the Sn-riched area *** results show that Al-Sn thin film is composed of an amorphous matrix and well-dispersed composite *** particle contains an Al-riched area and a Sn-riched *** Snriched area crystallizes and swallows up the Al-riched area gradually during heating through uphill diffusion of the Sn *** on the theoretical analysis and experimental results,an empirical model to explain the phase evolution process in the Al-Sn film was proposed.

关键词： Immiscible alloy Uphill diffusion Phase evolution Miedema theory

Precise drag prediction of airfoil flows by a new algebraic model

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2020年第1期36卷 35-43页

作者： meng-Juan xiao Zhen-Su She State Key Laboratory for Turbulence and Complex Systems College of EngineeringPeking UniversityBeijing100871China

We report the results of accurate prediction of lift(C L)and drag(C D)coefficients of two typical airfoil flows(NACA0012 and RAE2822)by a new algebraic turbulence model,in which the eddy viscosity is specified by a stress length(SL)function predicted by structural ensemble dynamics(SED)*** accuracy of the prediction of C D with error of a few counts(one count is 10−4)and of C L with error under 1%-2%are uniformly obtained for varying angles of attack(AoA),indicating an order of magnitude improvement of drag prediction accuracy compared to currently used models(typically around 20 to 30 counts).More interestingly,the SED-SL model is distinguished with fewer parameters of clear physical meaning,which quantify underlying turbulent boundary layer(TBL)with a universal multi-layer structure,and is thus promising to be more easily generalizable to complex *** use of the new model for the calibration of flow condition in experiment and the extraction of flow physics from numerical simulation data of aeronautic flows are discussed.

关键词： Lift and drag coefficients Airfoil Flows Stress Length Structural ensemble dynamics

Symmetry-based description of laminar-turbulent transition

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2019年第9期62卷 79-85页

作者： meng-Juan xiao Zhen-Su She Department of Mechanics and Engineering Science and State Key Laboratory for Turbulence and Complex Systems College of EngineeringPeking University

We report a simple but accurate description of flat plate transitional flow based on a structural ensemble dynamics(SED) theory of wall turbulence. It is postulated and verified by simulation data that a multi-layer stress length(SL) function ?12 presents a two-state structure in the streamwise x direction, characterizing the laminar-turbulent transition. The resulting algebraic model(called SED-SL) predicts correctly for the first time the entire streamwise profiles of the friction coefficient, Cf(x), of all seven sets of experimental(of e.g. T3 series) and simulations data of flat plate transitional flows, with varying incoming turbulence intensities Tu(or scales), superior to other closure models, with a two-state correlation for transition location Rex*= 3.3 × 10^6(1 +(Tu/0.65)^4)^-1.5/4. The extension to accurate description of transitional flows of engineering interests is discussed.

关键词： SED theory stress length multi-layer

Durable and stretchable nanocomposite ionogels with high thermoelectric property for low-grade heat harvesting

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2023年第1期66卷 267-280页

作者： xiao meng YAO Yuan LIU WenGuang School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional MaterialsTianjin UniversityTianjin300350China

Stretchable ionic thermoelectric(i-TE) materials have attracted growing interest in converting low-grade thermal energy into electricity. However, substantial improvement on i-TE performance of quasi-solid ionogels remains a significant ***, a nanocomposite ionogel with skin-like stretchability, high i-TE performance, thermostability and durability is prepared by hybridizing ionic liquid(IL) and Laponite nanosheets into waterborne polyurethane(WPU). With multiple H-bond, WPU can accommodate a higher content of IL, thereby improving its ionic conductivity. After cation exchange between IL and Laponite,the negatively charged Laponite sheets and released Na+can enhance the ionic Seebeck coefficient by enlarging thermophoretic mobility difference between the cations and anions in ionogel. Besides, incorporation of Laponite causes the decrease of thermal conductivity. Thus, the WPU-IL-Laponite ionogel exhibits a high ionic thermopower of 44.1 m V K-1, high ionic conductivity of 14.1 m S cm-1and low thermal conductivity of 0.43 W m-1K-1at a relative humidity of 90%. The corresponding ionic figure of merit of the ionogel is 1.90±0.27. Moreover, the ionogel demonstrates excellent durability during repeated stretching *** stretchable ionogel can be fabricated into ionic thermoelectric capacitor to convert thermal energy from solar radiation into electricity.

关键词： multiple H-bond waterborne polyurethane nanocomposite ionogel ionic thermoelectric capacitors low-grade heat harvesting

On-chip boost regulator with projected off- and on-time control

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第8期10卷 1223-1230页

作者： xiao-ru XU meng-lian ZHAO xiao-bo WU Institute of VLSI Design Zhejiang University Hangzhou 310027 China

The boost type power supplies are widely used in portable consumer electronics to step up the input voltage to adapt for the high voltage applications like light-emitting diode(LED) driving and liquid crystal display(LCD) *** these applications,a regulator with small volume,fewer external components and high efficiency is highly *** paper proposes a projected off-and on-time boost control scheme,based on which a monolithic IC with an on-chip VDMOS with 0.2 Ω on-state resistance RDS-ON was implemented in 1.5 μm bipolar-CMOS-DMOS(BCD) process.A 12 V,0.3 A boost regulator prototype is presented as *** projected off-time and modulated on-time in continuous conduction mode(CCM),a quasi fixed frequency,which is preferred for ripple control,is *** projected on-time and modulated off-time in discontinuous conduction mode(DCM),pulse frequency modulation(PFM) operation,which is beneficial to light load efficiency improvement,is achieved without extra control *** results show that an efficiency of 3% higher than that of a conventional method under 0.5 W output is achieved while a step load transient response comparable to that of current mode control is maintained as well.

关键词： Boost regulator Integrated circuits Pulse frequency modulation Projected off-time Projected on-time

Atomically precise nickel-sulfur clusters for efficient electrochemical 2,5-hydroxymethylfurfural oxidation

在线全文

学校读者我要写书评

暂无评论

Nano Research 2025年第1期18卷 140-148页

作者： Fen Wang Lu-Yu Liu Sha-Sha Cui Ting-Ting Li xiao-meng Yang Zhijuan Liu Yanyong Wang Henan Key Laboratory of Crystalline Molecular Functional Materials Henan International Joint Laboratory of Tumor Theranostical Cluster MaterialsGreen Catalysis Centerand College of ChemistryZhengzhou UniversityZhengzhou 450001China State Key Laboratory of Chem/Bio-sensing and Chemometrics College of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082China

Nickel sulfide exhibits excellent catalytic activity in the electrochemical 2,5-hydroxymethylfurfural oxidation reaction(HMFOR).However,due to the polydispersity of nanoparticles,it is difficult to establish a clear structure-activity relationship at the atomic *** this work,we have successfully synthesized atomically precise Ni_(6)(PET)_(12)and Ni_(4)(PET)_(8)clusters(PET:2-phenylethanethiol)for ***^(2+)and S_(2)-with atomic ratio of 1:2 was mainly existed in Ni_(6)(PET)_(12)and Ni_(4)(PET)_(8)to form Ni-S *** electrochemical test results have suggested both Ni_(6)(PET)_(12)and Ni_(4)(PET)_(8)displayed outstanding electrocatalytic ability for *** Ni_(6)(PET)_(12)exhibited better electrocatalytic ability than Ni_(4)(PET)_(8)with higher current density,lower overpotential and faster reaction *** superior electrochemical ability of Ni_(6)(PET)_(12)may be due to the enhanced adsorption towards HMF molecule with strong interaction towards hydroxyl group and furan ***,it found that the Ni^(2+)species in Ni_(6)(PET)_(12)could rapidly oxidized into Ni^(3+)species,which could spontaneously capture electron and proton from HMF for *** theoretical calculation demonstrated that the Ni_(6)(PET)_(12)process lower free energy barrier than Ni_(4)(PET)_(8)to display excellent electrocatalytic *** work is of great significance for designing efficient electrocatalysts for HMFOR.

关键词： atomically precise nickel nanoclusters 2 5-hydroxymethylfurfural electro-oxidation Ni3+species