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In-situ growth of polypyrrole on aramid nanofibers for electromagnetic interference shielding films with high stability

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Nano Research 2022年第9期15卷 8536-8545页

作者： Jianyu Zhou Sineenat Thaiboonrod Jianhui Fang Shaomei Cao Miao Miao xin feng Research Center of Nano Science and Technology College of SciencesShanghai UniversityShanghai 200444China National Nanotechnology Center(NANOTEC) National Science and Technology Development Agency(NSTDA)Thailand Science ParkPathum Thani 12120Thailand

Flexible electromagnetic interference(EMI)shielding films with high stability have shown promising prospect in harsh working conditions such as military,communication,and special protection ***,flexible aramid nanofibers@polypyrrole(ANF@PPy)films with high stability were easily achieved by the in-situ growth of PPy on the surface of ANF and the subsequent pressured-filtration film-forming *** the amount of pyrrole(Py)monomer is 40μL,the ANF@PPy(AP40)film exhibited excellent EMI shielding performance with shielding effectiveness(SE)of 41.69 dB,tensile strength of 96.01 MPa,and fracture strain of 21.95%at the thickness of 75.76μ***,the anticipated EMI shielding performance can be maintained even after being heated at 200℃in air,soaked in 3.5%NaCl solution,repeated folding for one million times,or burned directly,indicating superior environmental durability in harsh ***,it is believed that the ANF@PPy films with high stability offer a facile solution for practical protection for high-performance EMI shielding applications.

关键词： in-situ growth of polypyrrole(PPy)on aramid nanofibers(ANF) electromagnetic interference(EMI)shielding films high stability water-resistance thermal mechanical properties

CoSnO_(3)/C nanocubes with oxygen vacancy as high-capacity cathode materials for rechargeable aluminum batteries

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Green Energy & Environment 2023年第3期8卷 883-892页

作者： Shuainan Guo Mingquan Liu Haoyi Yang xin feng Ying Bai Chuan Wu School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Yangtze Delta Region Academy of Beijing Institute of Technology Jiaxing 314019China

Rechargeable aluminum batteries(RABs)are attractive cadidates for next-generation energy storage and conversion,due to the low cost and high safety of Al resources,and high capacity of metal Al based on the three-electrons reaction ***,the development of RABs is greatly limited,because of the lack of advanced cathode materials,and their complicated and unclear reaction *** the novel nanostructured transition metal and carbon composites is an effective route for obtaining ideal cathode *** this work,we synthesize porous CoSnO_(3)/C nanocubes with oxygen vacancies for utilizing as cathodes in RABs for the first *** intrinsic structure stability of the mixed metal cations and carbon coating can improve the cycling performance of cathodes by regulating the internal strains of the electrodes during volume *** nanocubes with porous structures contribute to fast mass transportation which improves the rate *** addition to this,abundant oxygen vacancies promote the adsorption affinity of cathodes,which improves storage *** a result,the CoSnO_(3)/C cathodes display an excellent reversible capacity of 292.1 mAh g^(-1) at 0.1 A g^(-1),a good rate performance with 109 mAh g^(-1) that is maintained even at 1 A g^(-1) and the provided stable cycling behavior for 500 ***,a mechanism of intercalation of Al^(3+)within CoSnO_(3)/C cathode is proposed for the electrochemical ***,this work provides a step toward the development of advanced cathode materials for RABs by engineering novel nanostructured mixed transition-metal oxides with carbon composite and proposes novel insights into chemistry for RABs.

关键词： Rechargeable aluminum batteries Mixed transition-metal oxides CoSnO_(3)/C Cathode material Oxygen vacancy

A tip clearance prediction model for multistage rotors and stators in aero-engines

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Chinese Journal of Aeronautics 2021年第2期34卷 343-357页

作者： Huibin SUN Jing WANG Kai CHEN Huateng XIA xin feng Zhiyong CHANG Key Laboratory of High Performance Manufacturing for Aero Engine Ministry of Industry and Information TechnologyNorthwestern Poly technical UniversityXi'an 710072China AECC South Industry Company Limited Zhuzhou 412002China

Tip clearances of multistage rotors and stators greatly affect aero-engines’ aerodynamic efficiency, stability and safety. The inevitable machining and assembly errors, as well as the complicated error propagation mechanism, cause overproof or non-uniform tip clearances. However, it is generally accepted that tip clearances are difficult to predict, even under assembly state. In this paper, a tip clearance prediction model is proposed based on measured error data. Some 3 D error propagation sub-models, regarding rotors, supports and casings, are built and combined. The complex error coupling relationship is uncovered using mathematical methods. Rotor and stator tip clearances are predicted and analyzed in different phase angles. The maximum, minimum and average tip clearances can be calculated. The proposed model is implemented by a computer program,and a case study illustrates its performance and verifies its feasibility. The results can be referred by engineers in assembly quality judgement and decision-making.

关键词： Tip clearance Prediction Error propagation model Rotor and stator Aero-engine Assembly

CO_2/N_2 separation using supported ionic liquid membranes with green and cost-effective [Choline][Pro]/PEG200 mixtures

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Chinese Journal of Chemical Engineering 2016年第11期24卷 1513-1521页

作者： Tengteng Fan Wenlong Xie Xiaoyan Ji Chang Liu xin feng Xiaohua Lu College of Chemistry and Chemical Engineering State Key Laboratory of Materials-Oriented Chemical EngineeringNanjing Tech University Division of Energy Science/Energy Engineering Lule? University of Technology

The high price and toxicity of ionic liquids(ILs) have limited the design and application of supported ionic liquid membranes(SILMs) for CO_2 separation in both academic and industrial fields. In this work, [Choline][Pro]/polyethylene glycol 200(PEG200) mixtures were selected to prepare novel SILMs because of their green and costeffective characterization, and the CO_2/N_2 separation with the prepared SILMs was investigated experimentally at temperatures from 308.15 to 343.15 K. The temperature effect on the permeability, solubility and diffusivity of CO_2 was modeled with the Arrhenius equation. A competitive performance of the prepared SILMs was observed with high CO_2 permeability ranged in 343.3–1798.6 barrer and high CO_2/N_2 selectivity from 7.9 to *** was also found that the CO_2 permeability increased 3 times by decreasing the viscosity of liquids from 370 to38 m Pa·s. In addition, the inherent mechanism behind the significant permeability enhancement was revealed based on the diffusion-reaction theory, i.e. with the addition of PEG200, the overall resistance was substantially decreased and the SILMs process was switched from diffusion-control to reaction-control.

关键词： CO2/N2separation Supported ionic liquid membranes (SILMs) [Choline][Pro]/PEG200 Diffusion-reaction theory

Static response of functionally graded multilayered two-dimensional quasicrystal plates with mixed boundary conditions

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Applied Mathematics and Mechanics(English Edition) 2021年第11期42卷 1599-1618页

作者： xin feng Liangliang ZHANG Yuxuan WANG Jinming ZHANG Han ZHANG Yang GAO College of Engineering China Agricultural UniversityBeijing 100083China College of Science China Agricultural UniversityBeijing 100083China China State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China

The unusual properties of quasicrystals(QCs)have attracted tremendous attention from *** this paper,a semi-analytical solution is presented for the static response of a functionally graded(FG)multilayered two-dimensional(2 D)decagonal QC rectangular plate with mixed boundary *** on the elastic theory of FG 2 D QCs,the state-space method is used to derive the state equations composed of partial differential along the thickness ***,the Fourier series expansion and the differential quadrature technique are utilized to simulate the simply supported boundary conditions and the mixed boundary conditions,***,the propagator matrix which connects the field variables at the upper interface to those at the lower interface of any homogeneous layer can be derived based on the state *** with the interface continuity condition,the static response can be obtained by imposing the sinusoidal load on the top surfaces of ***,the numerical examples are presented to verify the effectiveness of this method,and the results are very useful for the design and understanding of the characterization of FG QC materials in their applications to multilayered systems.

关键词： two-dimensional(2D)quasicrystal(QC)laminate functionally graded material(FGM) mixed boundary condition static response differential quadrature technique

First Enantioselective Synthesis of Daphneticin

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Chinese Chemical Letters 2003年第6期14卷 551-554页

作者： xin feng REN Kun PENG Xiao Chuan CHEN xin Gang XIE Ya Mu XIA xin Fu PAN Department of Chemistry National Laboratory of Applied Organic ChemistryLanzhou UniversityLanzhou 730000

An enantioselective total synthesis of chiral daphneticin is reported firstly.

关键词： Synthesis enantioselective coumarinolignoids daphneticin.

Multifunctional Waterborne Polyurethane Nanocomposite Films with Remarkable Electromagnetic Interference Shielding,Electrothermal and Solarthermal Performances

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Chinese Journal of Polymer Science 2023年第2期41卷 267-277页

作者： Ming-Ke Xu xin-Jie Luo Hao-Bin Zhang Yu Zhang Lulu Li xin-feng Zhou Zhong-Zhen Yu Beijing Key Laboratory of Advanced Functional Polymer Composites Beijing University of Chemical TechnologyBeijing100029China State Key Laboratory of Organic-Inorganic Composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China

To impart polymers with high electrical conductivity and satisfactory electromagnetic interference shielding efficiency,it is crucial to efficiently construct interconnecting networks of conductive nanofillers in polymer ***,on the basis of the three-dimensional(3D)skeleton and volume-exclusion effect of silane-modified tetra-needle ZnO(ST-ZnO)whiskers and the high conductivity of two-dimensional MXene nanosheets,multifunctional MXene/ST-ZnO/waterborne polyurethane(MTW)nanocomposite films are fabricated by coating of MXene on ST-ZnO followed by compounding with waterborne *** 3D four-needles of the whiskers facilitate the formation of an interconnecting network in the waterborne polyurethane matrix,while the coating of MXene efficiently makes the interconnecting network of the whiskers conductive at a low amount of the *** resultant MTW ternary nanocomposite film exhibits not only a high electrical conductivity of 4.8×10^(4)S/m,but also an excellent electromagnetic interference shielding effectiveness of over 70 dB in the X-band at a low thickness of 100µ*** addition,the ternary film also exhibits outstanding Joule heating performances with an equilibrium temperature of 113℃at a low driving voltage of 3 *** multifunctional nanocomposite films are promising for applications in portable and wearable electronics and flexible electromagnetic interference shielding devices.

关键词： Electrical conductivity Electromagnetic interference shielding Nanocomposite films Waterborne polyurethane MXene nanosheets

Research on a 50 kW digital inverter type plasma cutting power supply

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China Welding 2014年第2期23卷 51-56页

作者： Wang Zhenmin Fang Xiaoxin Zhang xin feng Yunliang School of Mechanical & Automotive Engineering South ChinaUniversity of Technology Guangzhou 510640

To improve energy transfer efficiency and quality controllability of plasma cutting process of thick plate, a 50 kW digital inverter type plasma cutting power supply is developed. The power supply main circuit is composed of two similar power electronic building blocks, using full-bridge high frequency inverter topology to achieve efficient energy transformation. To realize accurate digital control of the plasma cutting power supply and cooperative work of the two power electronic building blocks, the Cortex-M4 type ARM microprocessor-TM4C123GH6PGE is used as the cybernetic core of the control system. To improve the response performance and reliability of the power system, close-loop control and peak current feedback control modes are adopted. In the end, the experimental study of the performance testing and cutting of the developed prototype is carried out. The results indicate that the design is rational and feasible, and the developed high power plnsma cutting power supply works reliably with excellent performance.

关键词： plasma cutting digital control Cortex-M4 inverter

LAMINAR DEVELOPING FLOW IN THE ENTRANCE REGION OF ROTATING CURVED PIPES

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Journal of Hydrodynamics 2006年第4期18卷 418-423页

作者： MA Jian-feng SHEN xin-rong ZHANG Ming-kan ZHANG Ben-Zhao Department of Mechanics Zhejiang University Hangzhou 310027 China

Three-dimensional laminar flow in the entrance region of rotating curved pipes was investigated. The governing equations were written in an orthogonal curvilinear coordinate system and solved with a fully three-dimensional numerical method. The development of secondary flow, axial velocity, local and average friction factors for different cases of rotation were given and discussed in detail. The results show that rotation influences the flow structure and friction factor greatly and that the secondary flow is sink-type in the early stage of development and then turns to vortex structure. The average friction factor and the intensity of secondary flow have drastic decrease near the entrance. At some proper rotation, the average friction factor can be noticeably reduced.

关键词： developing flow secondary flow rotating curved pipe