检索结果-南通市图书馆

Physical Properties of Polymers under Soft and Hard Nanoconfinement: A Review

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第6期38卷 565-578页

作者： ming-Chao ma Yun-Long Guo University o f Michigan-Shanghai Jiao Tong University Joint Institute Shanghai Jiao Tong UniversityShanghai 200240China School of materials Science and Engineering Shanghai Jiao Tong UniversityShanghai200240China

Polymeric materials under nanoconfinements have substantially deviated physical properties with respect to the bulk,especially glass transition temperature,physical aging,and crystallization *** we highlight the leading methods for creating various confinement *** these systems,recent advances on hard and soft confinement effect for glass transition,physical aging,mechanical properties and crystallization of polymers are reviewed in ***,as nanoconfined systems in extreme conditions are experimentally inaccessible,simulation results describing confinement effect on such systems are also discussed.

关键词： Nanoconfinement Glass transition temperature Physical aging Mechanical properties Crystallization

Conductive polypyrrole incorporated nanocellulose/MoS_(2)film for preparing flexible supercapacitor electrodes

在线全文

学校读者我要写书评

暂无评论

Frontiers of materials Science 2021年第2期15卷 227-240页

作者： Qi YUAN ming-Cuo ma Research Center of Biomass Clean Utilization Beijing Key Laboratory of Lignocellulosic ChemistryCollege of Materials Science and TechnologyBeijing Forestry UniversityBeijing 100083China

Conductive films have emerged as appealing electrode materials in flexible supercapacitors owing to their conductivity and mechanical ***,the unsatisfactory electrode structure induced poor output performance and undesirable cycling stability limited their ***,a well-designed film was manufactured by the vacuum filtration and in-situ polymerization method from cellulose nanofibrils(CNFs),molybdenum disulfide(MoS_(2)),and *** electrode presented an outstanding mechanical strength(21.3 MPa)and electrical conductivity(9.70 S cm^(-1)).Meanwhile,the introduce of hydrophilic CNFs induced a desirable increase in diffusion path of electrons and ions,along with the synergistic effect among the three components,further endowed the electrode with excellent specific capacitance(0.734 F·cm^(-2))and good cycling stability(84.50%after 2000 charge/discharge cycles).More importantly,the flexible all-solid-state symmetric supercapacitor delivered a high specific capacitance(1.39 F·cm^(-2)at 1 ma·cm^(-2))and a volumetric energy density(6.36 mW·h·cm^(-3)at the power density of 16.35 mW cm^(-3)).This work provided a method for preparing composite films with desired mechanical and electrochemical performance,which can broaden the high-value applications of nanocellulose.

关键词： cellulose nanofibril molybdenum disulfide polypyrrole flexible supercapacitor

Synchronization analysis on cascaded multilevel converters with distributed 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) 2008年第2期9卷 190-198页

作者： ming-yao ma Xiang-ning HE School of Electrical Engineering Zhej iang University Hangzhou 310027 China

Cascaded multilevel converters built with integrated modules have many advantages such as increased power density,flexible distributed control,multi-functionality,increased reliability and short design ***,the system performance will be affected due to the synchronization errors among each integrated *** paper analyzes the impact of the three kinds of synchronization errors on the whole system performance,as well as detailed synchronization *** valuable conclusions are derived from the theoretical analysis,simulations and experimental results.

关键词： Cascaded multilevel converter Integrated module Synchronization

Deciphering and integrating invariants for neural operator learning with various physical mechanisms

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第4期11卷 111-122页

作者： Rui Zhang Qi Meng Zhi-ming ma Academy of mathematics and Systems Science Chinese Academy of Sciences(CAS) Microsoft Research

Neural operators have been explored as surrogate models for simulating physical systems to overcome the limitations of traditional partial differential equation(PDE) solvers. However, most existing operator learning methods assume that the data originate from a single physical mechanism, limiting their applicability and performance in more realistic scenarios. To this end, we propose the physical invariant attention neural operator(PIANO) to decipher and integrate the physical invariants for operator learning from the PDE series with various physical mechanisms. PIANO employs self-supervised learning to extract physical knowledge and attention mechanisms to integrate them into dynamic convolutional *** to existing techniques, PIANO can reduce the relative error by 13.6%–82.2% on PDE forecasting tasks across varying coefficients, forces or boundary conditions. Additionally, varied downstream tasks reveal that the PI embeddings deciphered by PIANO align well with the underlying invariants in the PDE systems, verifying the physical significance of PIANO.

关键词： neural operator PDE solver contrastive learning physical invariants

Long-term field measurement and analysis of the natural wind characteristics at the site of Xi-hou-men Bridge

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 Zhejiang University-Science A(Applied Physics & Engineering) 2012年第3期13卷 197-207页

作者： ming LIU Hai-li LIAO ming-shui LI Cun-ming ma Mei YU Research Center for Wind Engineering Southwest Jiaotong University Chengdu 610031 China Chongqing Jiaotong University Chongqing 400074 China

In order to investigate the wind characteristics of coastal areas of China, a long-term field measurement of natural wind was carried out. Based on the field measurement results, this paper presents the natural wind characteristics of typhoons and strong monsoons at the site of Xi-hou-men Bridge, including mean wind speed, mean wind direction, mean wind elevation angle, turbulent intensity, gust factor, turbulence integral length scales, power spectrum of wind speed and spatial correlation of gusty wind, the profiles of mean wind speed and turbulent intensity, etc. The correlation among wind characteristics is analyzed in detail, and the similarities and differences of wind characteristics between typhoons and monsoons are analyzed. These results can pro- vide detailed wind characteristics of coastal areas of China.

关键词： Wind characteristics Field measurement Wind spectrum Wind profiles Spatial correlation

Efficiency of Profinite Rigidity of Triangle Groups

在线全文

学校读者我要写书评

暂无评论

Acta mathematica Sinica,English Series 2022年第10期38卷 1939-1948页

作者： Ji ming ma Zi Xi WANG School of mathematical Sciences Fudan UniversityShanghai 200433P.R.China

It is already known that finitely-generated Fuchsian groups are profinitely rigid among all lattices of connected Lie groups by the result of Bridson,Conder and *** the triangle groups are distinguished among themselves by their finite *** focus on the question about quantifying the size of a quotient which separates two triangle groups and give an explicit upper bound.

关键词： Triangle groups profinite completion finite quotients

Effect of shot peening on hydrogen embrittlement of high strength steel

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 2016年第6期23卷 667-675页

作者： Xin-feng Li Jin Zhang ming-ming ma Xiao-long Song State Key Laboratory for Mechanical Behavior of materials Xi'an Jiaotong University Department of Geosciences State University of New YorkStony Brook Department of Heat Treatment and Surface Treatment AVIC Aircraft Co. Ltd.Xi'an Break Branch

The effect of shot peening（SP） on hydrogen embrittlement of high strength steel was investigated by electrochemical hydrogen charging, slow strain rate tensile tests, and hydrogen permeation tests. Microstructure observation, microhardness, and X-ray diffraction residual stress studies were also conducted on the steel. The results show that the shot peening specimens exhibit a higher resistance to hydrogen embrittlement in comparison with the no shot peening（NSP） specimens under the same hydrogen-charging current density. In addition, SP treatment sharply decreases the apparent hydrogen diffusivity and increases the subsurface hydrogen concentration. These findings are attributed to the changes in microstructure and compressive residual stress in the surface layer by SP. Scanning electron microscope fractographs reveal that the fracture surface of the NSP specimen exhibits the intergranular and quasi-cleavage mixed fracture modes, whereas the SP specimen shows only the quasi-cleavage fractures under the same hydrogen charging conditions, implying that the SP treatment delays the onset of intergranular fracture.

关键词： high strength steel shot peening hydrogen embrittlement cracking fracture inclusions

Oscillating friction of nanoscale capillary bridge

在线全文

学校读者我要写书评

暂无评论

Friction 2022年第2期10卷 200-208页

作者： Shuai WU Yuqing HE Quanshui ZHENG ming ma Department of Engineering Mechanics.Tsinghua University Beijing 100084China Center for Nano and Micro Mechanics Tsinghua University.Beijing 100084China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084.China Department of Mechanical Engineering.Tsinghua University Beijing 100084China

The presence of a capillary bridge between solid surfaces is ubiquitous under ambient ***,it leads to a continuous decrease of friction as a function of bridge ***,using molecular dynamics we show that for a capillary bridge with a small radius confined between two hydrophilic elastic solid surfaces,the friction oscillates greatly when decreasing the bridge *** underlying mechanism is revealed to be a periodic ordered-disordered transition at the liquid–solid *** transition is caused by the balance between the surface tension of the liquid–vapor interface and the elasticity of the *** balance introduces a critical size below which the friction *** on the mechanism revealed,a parameter-free analytical model for the oscillating friction was derived and found to be in excellent agreement with the simulation *** results describe an interesting frictional phenomenon at the nanoscale,which is most prominent for layered materials.

关键词： capillary bridge nano-confinement elasticity atomically smooth surface

Construction of smart inorganic nanoparticle-based ultrasound contrast agents and their biomedical applications

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2015年第13期60卷 1170-1183页

作者： ming ma Hangrong Chen Jianlin Shi State Key Laboratory of High Performance Ceramics and Superfine Microstructures Shanghai Institute of CeramicsChinese Academy of Sciences

Ultrasound(US) imaging in combination with US contrast agents(UCAs) is a powerful tool in the modern biomedical field because of its high spatial resolution, easy access to patients and minimum *** microbubble-based UCAs have been widely used in clinical diagnosis; however, they are only limited to the blood pool imaging and not applicable to the tissue-penetrated imaging due to their large particle size and structural instability. Inorganic nanoparticles(NPs), such as silica,gold and Fe x O y, featured with both satisfactory echogenic properties and structural stability have the potential to be used as a new generation of UCAs. In this review, we present the most recent progresses in the tailored construction of inorganic UCAs and their biomedical applications in the US imaging-involved fields. Firstly, the typical inorganic NPs with different structures including solid, hollow and multiple-layer forms will be comprehensively introduced in terms of their structure design,physicochemical property, US imaging mechanism and diverse applications; secondly, the recent progress in exploring the gas-generating inorganic NP system for US imaging purpose will be reviewed, and these intelligent UCAs are multifunctional for simultaneous US imaging and disease therapy; thirdly, several nanocomposite platforms newly constructed by combining inorganic UCAs with other functional components will be presented anddiscussed. These multifunctional NPs are capable of further enhancing the imaging resolution by providing more comprehensive anatomical information *** but not the least, the design criteria for developing promising UCAs to satisfy both clinical demands and optimized US imaging capability will be discussed and summarized in this review.

关键词： Inorganic nanoparticle .Ultrasoundimaging . Theranostic . Contrast agent