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Applied Mathematics and Mechanics(English Edition) 2019年第4期40卷 435-448页

作者： Daiwen JIANG Hui ZHANG Baochun FAN Zijie ZHAO Jian LI Mingyue GUI Science and Technology on Transient physics Laboratory Nanjing University of Science and Technology department of Mathematics Imperial College London

In this paper, the control of turbulent channel flow by space-dependent electromagnetic force and the mechanism of drag reduction are investigated with the direct numerical simulation(DNS) methods for different Reynolds numbers. A formulation is derived to express the relation between the drag and the Reynolds shear stress. With the application of optimal electromagnetic force, the in-depth relations among characteristic structures in the flow field, mean Reynolds shear stress, and the effect of drag reduction for different Reynolds numbers are discussed. The results indicate that the maximum drag reductions can be obtained with an optimal combination of parameters for each case of different Reynolds numbers. The regular quasi-streamwise vortex structures, which appear in the flow field, have the same period with that of the electromagnetic *** structures suppress the random velocity fluctuations, which leads to the absolute value of mean Reynolds shear stress decreasing and the distribution of that moving away from the wall. Moreover, the wave number of optimal electromagnetic force increases,and the scale of the regular quasi-streamwise vortex structures decreases as the Reynolds number increases. Therefore, the rate of drag reduction decreases with the increase in the Reynolds number since the scale of the regular quasi-streamwise vortex structures decreases.

关键词： flow control drag reduction electromagnetic force turbulent channel flow

Structure-guided Capacitance Relationships in Oxidized Graphene Porous Materials Based Supercapacitors

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Energy & Environmental Materials 2023年第4期6卷 58-69页

作者： Srinivas Gadipelli Hanieh Akbari Juntao Li Christopher A.Howard Hong Zhang Paul R.Shearing Dan J.L.Brett college of physics Sichuan UniversityChengdu 610064China Electrochemical Innovation Lab Department of Chemical EngineeringUniversity College LondonLondonWC1E 7JEUK department of physics and Astronomy University College LondonLondonWC1E 6BTUK

Supercapacitors formed from porous carbon and graphene-oxide(GO)materials are usually dominated by either electric double-layer capacitance,pseudo-capacitance,or *** to these combined features,reduced GO materials have been shown to offer superior capacitance over typical nanoporous carbon materials;however,there is a significant variation in reported values,ranging between 25 and 350 F g^(−1).This undermines the structure(e.g.,oxygen functionality and/or surface area)-performance relationships for optimization of cost and scalable *** work demonstrates important structure-controlled charge storage *** this,a series of exfoliated graphene(EG)derivatives are produced via thermal-shock exfoliation of GO precursors and following controlled graphitization of EG(GEG)generates materials with varied amounts of porosity,redox-active oxygen groups and graphitic *** results show significantly varied capacitance values between 30 and 250 F g^(−1)at 1.0 A g^(−1)in GEG structures;this suggests that for a given specific surface area the redox-active and hydrophilic oxygen content can boost the capacitance to 250–300%higher compared to typical mesoporous carbon *** with identical oxygen functionality show a surface area governed *** allows to establish direct structure-performance relationships between 1)redox-active oxygen functional concentration and capacitance and 2)surface area and capacitance.

关键词： electric double-layer capacitance graphene-oxide pseudocapacitance structure-performance relationships supercapacitors

Natural Connectivity of Complex Networks

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Chinese physics Letters 2010年第7期27卷 295-298页

作者：吴俊 Mauricio Barahona 谭跃进邓宏钟 college of Information Systems and Management National University of Defense Technology Changsha 410073 Institute for Mathematical Sciences Imperial College London London SW7 2PG United Kingdom department of bioengineering Imperial College London London SW7 2AZ United Kingdom

The concept of natural connectivity is reported as a robustness measure of complex networks. The natural connectivity has a clear physical meaning and a simple mathematical formulation. It is shown that the natural connectivity can be derived mathematically from the graph spectrum as an average eigenvalue and that it changes strictly monotonically with the addition or deletion of edges. By comparing the natural connectivity with other typical robustness measures within a scenario of edge elimination, it is demonstrated that the naturM connectivity has an acute discrimination which agrees with our intuition.

关键词： GRAPH connectivity ROBUST control MATHEMATICAL analysis MONOTONE operators EIGENVALUES NEURAL networks (Computer science)

Model Construction and Numerical Simulation for Hydroplaning of Complex Tread Tires

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Complex System Modeling and Simulation 2022年第4期2卷 322-333页

作者： Senwang Tao Jinbiao Wang Ruonan Dong the School of Mechanical Engineering Hefei University of TechnologyHefei 230009China. the department of bioengineering Imperial College LondonLondonSW72AZUK

Euler-Lagrange coupling method is used to establish the fluid-structure interaction model for tires with different tread patterns by obtaining the grounding mark and normal contact force between tire and the road surface during tire *** altering of load force,tire pressure,and water film thickness in relation to the effect on tire-road force during both constant speed and critical hydroplaning speed was *** show that the critical hydroplaning speed and normal contact force between tire and the road surface are positively correlated with vehicle load and tire pressure and negatively correlated with water film *** language is used to develop the pre-processing plug-ins to achieve parametric modeling and rapid creation of Finite Element Analysis(FEA)model to reduce time costs,and the effectiveness of the plug-ins is verified through comparative tests.

关键词： Euler-Lagrange coupling method hydroplaning process analysis hydroplaning speed simulation Python efficient modeling

Multiple radial phosphorus segregations in GaAsP core-shell nanowires

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Nano Research 2021年第1期14卷 157-164页

作者： H.Aruni Fonseka Yunyan Zhang James A.Gott Richard Beanland Huiyun Liu Ana M.Sanchez department of physics University of WarwickCoventry CV47ALUK department of Electronic and Electrical Engineering University College LondonLondon WC1E 7JEUK

Highly faceted geometries such as nanowires are prone toform self-formed features,especially those that are driven by *** these features is important in preventing their formation,understanding their effects on nanowire properties,or engineering them for *** elemental segregation lines that run along the radii of the hexagonal cross-section have been a common observation in alloy semiconductor ***,in GaAsP nanowires,two additional P rich bands are formed on either side of the primary band,resulting in a total of three segregation bands in the vicinity of three of the alternating *** bands are less intense than the primary band and their formation can be attributed to the inclined nanofacets that form in the vicinity of the *** formation of the secondary bands requires a higher composition of P in the shell,and to be grown under conditions that increase the diffusivity difference between As and ***,it is observed that the primary band can split into two narrow and parallel *** can take place in all six radii,making the cross sections to have up to a maximum of 18 radial segregation *** controlled growth,these features could be exploited to assemble multiple different quantum structures in a new dimension(circumferential direction)within nanowires.

关键词： compound semiconductor alloys radial segregations three-fold symmetry surface chemical potential

All-optical image denoising using a diffractive visual processor

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Light(Science & Applications) 2024年第3期13卷 429-445页

作者： Çağatay Işıl Tianyi Gan Fazil Onuralp Ardic Koray Mentesoglu Jagrit Digani Huseyin Karaca Hanlong Chen Jingxi Li Deniz Mengu Mona Jarrahi Kaan Akşit Aydogan Ozcan Electrical and Computer Engineering department University of CaliforniaLos AngelesCA 90095USA bioengineering department University of CaliforniaLos AngelesCA 90095USA California NanoSystems Institute(CNSI) University of CaliforniaLos AngelesCA 90095USA university college london Department of Computer ScienceLondonUnited Kingdom

Image denoising,one of the essential inverse problems,targets to remove noise/artifacts from input *** general,digital image denoising algorithms,executed on computers,present latency due to several iterations implemented in,e.g.,graphics processing units(GPUs).While deep learning-enabled methods can operate non-iteratively,they also introduce latency and impose a significant computational burden,leading to increased power ***,we introduce an analog diffractive image denoiser to all-optically and non-iteratively clean various forms of noise and artifacts from input images–implemented at the speed of light propagation within a thin diffractive visual processor that axially spans<250×λ,whereλis the wavelength of *** all-optical image denoiser comprises passive transmissive layers optimized using deep learning to physically scatter the optical modes that represent various noise features,causing them to miss the output image Field-of-View(FoV)while retaining the object features of *** results show that these diffractive denoisers can efficiently remove salt and pepper noise and image rendering-related spatial artifacts from input phase or intensity images while achieving an output power efficiency of~30–40%.We experimentally demonstrated the effectiveness of this analog denoiser architecture using a 3D-printed diffractive visual processor operating at the terahertz *** to their speed,power-efficiency,and minimal computational overhead,all-optical diffractive denoisers can be transformative for various image display and projection systems,including,e.g.,holographic displays.

关键词： remove rendering holographic

All-angle reflectionless negative refraction with ideal photonic Weyl metamaterials

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Light(Science & Applications) 2022年第10期11卷 2444-2450页

作者： Yachao Liu Guo Ping Wang John B.Pendry Shuang Zhang college of Electronics and Information Engineering Shenzhen University518060 ShenzhenChina School of physics&Astronomy University of BirminghamBirmingham B152TTUK The Blackett Laboratory Department of PhysicsImperial College LondonLondon SW72AZUK department of physics University of Hong KongHong KongChina department of Electrical&Electronic Engineering University of Hong KongHong KongChina

Negative refraction,an unnatural optical phenomenon in which the incident and the refracted waves reside on the same side of the surface normal,has been demonstrated with the invention of negative index media based on artificially engineered photonic structures called *** has received wide attention due to its potential applications in imaging,nonlinear optics,and electromagnetic ***,it is highly challenging to realize negative refraction operating at all angles and with the perfect *** this work,leveraging the recent development in topological photonics,we propose to realize reflection less negative refraction for all incident angles with a topological *** proposed metamaterial possesses two Weyl points of opposite topological *** interfacing the metamaterial with a perfect electric conductor(PEC)or a perfect magnetic conductor(PMC),the Fermi arc connecting the two Weyl points can take the form of a half-circle possessing a positive or a negative refractive ***,due to the topological protection,there is no reflection at the interface between the PEC and PMC covered areas,leading to the observation of all-angle negative refraction without reflection at the *** work provides a new platform for manipulating the propagation of surface waves,which may find applications in the construction of integrated photonic devices.

关键词： refraction topological perfect

Storage Stability in Reversion Mutation of a Rice Line Devoid of LOX-1, 2 Acquired by Ion Beam Irradiation

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Plasma Science and Technology 2009年第1期11卷 116-121页

作者：蒋家月吴瑾华吴跃进宋美王相勤刘斌美余增亮 Key Laboratory of Ion Beam bioengineering Institute of Plasma PhysicsChinese Academy of Sciences college of Tea & Food Science and Technology Anhui Agricultural University department of Biochemistry and Molecular Biology Virginia Commonwealth University Key Laboratory of Ion Beam bioengineering Institute of Plasma PhysicsChinese Academy of Sciences

The effect of absence of lipoxygenase isoenzyme （LOX） on storage stability was investigated. Rice mutant 1297 without lipoxygenase isoenzyme-1 （LOX-1） or lipoxygenase isoenzyme-2 （LOX-2） generated by ion beam irradiation from Wanjian2090 and reversion mutant RM1297 with LOX-1 and LOX-2 were subjected to an accelerated-aging experiment. Shanyou63 （with LOX-1 and LOX-2 ） served as control. Results showed that the germination and dehydrogenase activity decreased while the electrical conductivity and free fatty acid content increased in all varieties with accelerated aging. In 1297 that lacked LOX-1 and 2, there were slight changes in germination, dehydrogenase activity, membrane permeability and free fatty acid content during the thirty-day accelerated-aging experiment. But in varieties with LOX-1 and LOX-2, significant changes were observed, suggesting that LOX-1, 2 might be a definite factor which influenced seed lifespan. This study also indicates that ion beam irradiation may be used as mutagen to generate mutant and reversion mutants for biological study and could become a new direction in ion beam application.

关键词： rice storage stability reversion mutant ion beam irradiation

Sigma-Meson from General Color Symmetry Model for Quantum Chromodynamics

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Chinese physics Letters 1997年第8期14卷 573-576页

作者： LÜXiao-fu LIU Yu-xin ZOU Bing-song DING Hui-ming ZHAO En-gang department of physics Sichuan UniversityChengdu 610064 department of physics Peking UniversityBeijing 100871 Institute of Theoretical physics Chinese Academy of SciencesBeijing 100080 department of physics Jilin UniversityChangchun 130023 Queen Mary and Westfield college London El 4NSU.K.

The property of σ-meson or f0(400-1200)is studied in the general color symmetry model(GCM)for quantum *** recent determined values of mσ,fσand fπin GCM,the isoscalarππS-wave amplitude is calculated without any free *** T-matrix pole for f0(400-1200)is found to be 1011-i 284MeV,which is very close to the Particle Data Group value(400-1200)-i(300-500)MeV.

关键词： parameter. symmetry meson

Effects of in-plane stiffness and charge transfer on thermal expansion of monolayer transition metal dichalcogenide

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Chinese physics B 2015年第2期24卷 343-349页

作者：王占雨周艳丽王雪青王飞孙强郭正晓贾瑜 International Joint Research Laboratory for Quantum Functional Materials of Henan Zhengzhou University School of physics and Engineering Zhengzhou University department of Mechanical and Electrical Engineering Henan Industry and Trade Vocational College department of Chemistry University College London

The temperature dependence of lattice constants is studied by using first-principles calculations to determine the effects of in-plane stiffness and charge transfer on the thermal expansions of monolayer semiconducting transition metal *** the corresponding bulk material,our simulations show that monolayer MX2（M = Mo and W;X = S,Se,and Te） exhibits a negative thermal expansion at low temperatures,induced by the bending *** transition from contraction to expansion at higher temperatures is ***,the thermal expansion can be tailored regularly by alteration of the M or X *** analysis shows that the positive thermal expansion coefficient is determined mainly by the in-plane stiffness,which can be expressed by a simple *** the regularity of this change can be attributed to the difference in charge transfer between the different *** findings should be applicable to other two-dimensional systems.

关键词： transition metal dichalcogenide thermal expansion phonon