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Rare Metals 2006年第z2期25卷 184-188页

作者： PARK Sook Hee KANG chan Hyoung Department of Advanced Materials Engineering Korea Polytechnic University Shihung Kyonggi-do 429-793 Korea

Employing Li2CO3, NiO, Co3O4, and MnCO3 powders as starting materials, Li[Ni1/3Co1/3Mn1/3]O2 was synthesized by solid-state reaction method. Various grinding aids were applied during milling in order to optimize the synthesis process. After successive heat treatments at 650 and 950 ℃, the prepared powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy, and transmission electron microscopy. The powders prepared by adding salt (NaCl) as grinding aid exhibit a clear R3m layer structure. The powders by other grinding aids like heptane show some impurity peaks in the XRD pattern. The former powders show a uniform particle size distribution of less than 1 μm average size while the latter shows a wide distribution ranging from 1 to 10 μm. Energy dispersive X-ray (EDX) analysiss show that the ratio of Ni, Co, and Mn content in the powder is approximately 1/3, 1/3, and 1/3, respecively. The EDX data indicate no incorporation of sodium or chlorine into the powders. Charge-discharge tests gave an initial discharge capacity of 160 mAh·g-1 for the powders with NaCl addition while 70 mAh·g-1 for the powders with heptane.

关键词： lithium ion battery cathode materials layered structure solid-state method discharge density

Numerical simulation of particle formation and evolution in a vehicle exhaust plume using the bimodal Taylor expansion method of moments

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Particuology 2019年第2期17卷 46-55页

作者： Shuyuan Liu Tat Leung chan Huijie Liu Department of Mechanical Engineering The Hong Kong Polytechnic University Kowloon Hong Kong China

The bimodal Taylor expa nsion method of moments (B-TEMOM) model scheme was developed to simulate the formation and evolution of vehicle exhaust particles. Two independent types of log-normal particle size distributions were selected in the B-TEMOM model scheme, comprising large and small particles to represent background (i.e., the surrounding environment) and vehicle exhaust particles, respectively. Concentration distributions of exhaust and background particles derived using this model scheme were verified against results from a moving secti onal method and the bimodal quadrature method of moments, showing excellent agreement. The effects of vehicle tailpipe ex 让 cond 让 ions (e.g., exhaust particle concentrations and velocity), sulfurcontent, and relative humidity on the evoluti on of particles were investigated numerically. Both two-dimensional and three-dimensional numerical simulations showed that tailpipe exit velocity and relative humid让y did not greatly affect the steady-state concentrations or the diameters of particles in urban atmospheres. Although an increase in sulfur content had little effect on the particle concentration, it led to background particles with larger geometric average diameter entering the environment. This coupled CFD-B-TEMOM numerical model provides a simple but accurate and efficient method for studying bimodal aerosol dynamics.

关键词： Vehicle exhaust particles Bimodal Taylor expansi on method of moments Homogeneous nucleation Coagulation Tailpipe exit velocity Sulfur content and ambient relative humidity

The Distance Matching Extension in K_(1,k)-free Graphs with High Local Connectedness

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Acta Mathematicae Applicatae Sinica 2022年第1期38卷 37-43页

作者： Wei-chan LIU Gui-ying YAN Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

A matching is extendable in a graph G if G has a perfect matching containing it.A distance q matching is a matching such that the distance between any two distinct matching edges is at least *** this paper,we prove that any distance 2k-3 matching is extendable in a connected and locally(k-1)-connected K1,k-free graph of even ***,we also prove that any distance q matching M in an r-connected and locally(k-1)-connected K1,k-free graph of even order is extendable provided that|M|is bounded by a function on r,k and *** results improve some results in[*** Theory 93(2020),5–20].

关键词： distance matching extension perfect matching K1,k-free graph local connectedness

Multi-temporal analysis of past and future land cover change in the highly urbanized state of Selangor,Malaysia

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Ecological Processes 2022年第1期11卷 93-107页

作者： Majid Azari Lawal Billa Andy chan Department of Civil Engineering University of Nottingham MalaysiaJalan Broga43500 SemenyihSelangorMalaysia School of Environmental and Geographical Sciences University of Nottingham MalaysiaJalan BrogaSelangor 43500 SemenyihMalaysia

Background:This study analysed the multi-temporal trend in land cover,and modelled a future scenario of land cover for the year 2030 in the highly urbanized state of Selangor,*** study used a Decision Forest-Markov chain model in the land change modeller(LCM)tool of TerrSet *** cover maps of 1999,2006 and 2017 were classified into 5 classes,namely water,natural vegetation,agriculture,built-up land and cleared land.A simulated land cover map of 2017 was validated against the actual land cover map *** Area Under the Curve(AUC)value of 0.84 of Total Operating Characteristics(TOC)and higher percentage of components of agreement(Hits+Correct rejection)compared to components of disagreement(Misses+False alarm+Wrong hits)indicated successful validation of the ***:The results showed between the years 1999 to 2017 there was an increase in built-up land cover of 608.8 km^(2)(7.5%),and agricultural land 285.5 km^(2)(3.5%),whereas natural vegetation decreased by 831.8 km^(2)(10.2%).The simulated land cover map of 2030 showed a continuation of this trend,where built-up area is estimated to increase by 723 km^(2)(8.9%),and agricultural land is estimated to increase by 57.2 km^(2)(0.7%),leading to a decrease of natural vegetation by 663.9 km^(2)(8.1%)for the period 2017 to *** spatial trend of land cover change shows built-up areas mostly located in central Selangor where the highly urbanized and populated cities of Kuala Lumpur and Putrajaya and the Klang valley are ***:The future land cover modelling indicates that built-up expansion mostly takes place at edges of existing urban *** results of this study can be used by policy makers,urban planners and other stakeholders for future decision making and city planning.

关键词： Land cover modelling Land use and land cover Land change modeller Markov chain model Selangor Malaysia

Learning from a carbon dioxide capture system dataset: Application of the piecewise neural network algorithm

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Petroleum 2017年第1期3卷 56-67页

作者： Veronica chan Christine chan Energy Informatics Laboratory Faculty of Engineering and Applied ScienceUniversity of ReginaReginaSK S4S0A2Canada

This paper presents the application of a neural network rule extraction algorithm,called the piecewise linear artificial neural network or PWL-ANN algorithm,on a carbon capture process system *** objective of the application is to enhance understanding of the intricate relationships among the key process *** algorithm extracts rules in the form of multiple linear regression equations by approximating the sigmoid activation functions of the hidden neurons in an artificial neural network(ANN).The PWL-ANN algorithm overcomes the weaknesses of the statistical regression approach,in which accuracies of the generated predictive models are often not satisfactory,and the opaqueness of the ANN *** results show that the generated PWL-ANN models have accuracies that are as high as the originally trained ANN models of the four datasets of the carbon capture process *** analysis of the extracted rules and the magnitude of the coefficients in the equations revealed that the three most significant parameters of the CO_(2) production rate are the steam flow rate through reboiler,reboiler pressure,and the CO_(2) concentration in the flue gas.

关键词： Carbon dioxide capture process system Artificial neural network Rule extractions Non-linear modeling Linear regression

On the Small Time Asymptotics of the Dynamical Φ_(1)^(4)Model

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Acta Mathematica Sinica,English Series 2021年第3期37卷 436-446页

作者： Bing Guang CHEN Xiang chan ZHU Academy of Mathematics and Systems Science Chinese Academy of ScienceBeijing 100190P.R.China Department of Mathematics University of BielefeldD-33615 BielefeldGermany

In this paper,we establish a small time large deviation principle(small time asymptotics)for the dynamicalΦ_(1)^(4)model,which not only involves study of the space-time white noise with intensity√ε,but also the inv... 详细信息

关键词： Φ_(1)^(4)model space-time white noise small time asymptotics large deviation

Dirac-like cone-based electromagnetic zero-index metamaterials

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Light(Science & Applications) 2021年第11期10卷 2048-2066页

作者： Yang Li C.T.chan Eric Mazur State Key Laboratory of Precision Measurement Technology and Instrument Department of Precision InstrumentTsinghua UniversityBeijingChina Department of Physics Hong Kong University of Science and TechnologyKowloonHong KongChina John A.Paulson School of Engineering and Applied Sciences Harvard UniversityCambridgeMAUSA

Metamaterials with a Dirac-like cone dispersion at the center of the Brillouin zone behave like an isotropic and impedance-matched zero refractive index material at the Dirac-point *** metamaterials can be realized in the form of either bulk metamaterials with efficient coupling to free-space light or on-chip metamaterials that are efficiently coupled to integrated photonic *** materials enable the interactions of a spatially uniform electromagnetic mode with matter over a large area in arbitrary *** unique optical property paves the way for many applications,including arbitrarily shaped high-transmission waveguides,nonlinear enhancement,and phase mismatch-free nonlinear signal generation,and collective emission of many *** review summarizes the Dirac-like cone-based zero-index metamaterials’fundamental physics,design,experimental realizations,and potential applications.

关键词： index collective realization

Investigation on static routing and resource assignment of elastic all-optical switched intra-datacenter networks

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Science China(Information Sciences) 2016年第10期59卷 60-75页

作者： Limei PENG Kiejin PARK chan-Hyun YOUN Department of Industrial Engineering Ajou University Department of Integrative Systems Engineering Ajou University Department of Electrical Engineering Korea Advanced Institute of Science and Technology

In this paper, we explore the issue of static routing and spectrum/IT resource assignment(RSIA)of elastic all-optical switched intra-datacenter networks(intra-DCNs) by proposing anycast- and manycastbased integer linear programming(ILP) models. The objective is to jointly optimize the DCN resources, i.e.,network transmission bandwidth and IT resources, under different situations. First, for given service-request matrices with unknown network transmission bandwidth and IT resources, we propose anycast and manycast ILP models to minimize the maximum numbers of required network and IT resources to accommodate all the service requests. For anycast RSIA issue, we proposed two different ILP models that are based on node-arc and link-path methods, respectively. Node-arc based manycast ILP model is also proposed for the first time to our knowledge. Second, for given network transmission bandwidth and IT resources and known servicerequest matrices, we propose node-arc based anycast ILP models to maximize the total number of successfully served service requests. To evaluate the efficiency of anycast and manycast models, all proposed ILP models are evaluated and compared with unicast ILP models. Simulation results show that anycast and manycast ILP models perform much better in efficiently using DCN resources and successfully accommodating more service requests when compared to unicast ILP models under the same network conditions.

关键词： datacenter networks(DCNs) intra-DCN RSIA ILP models anycast manycast

Phenolic constituents and anticancer properties of Morus alba(white mulberry) leaves

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Journal of Integrative Medicine 2020年第3期18卷 189-195页

作者： Eric Wei Chiang chan Siu Kuin Wong Joseph Tangah Tomomi Inoue Hung Tuck chan Faculty of Applied Sciences UCSI University56000 CherasKuala LumpurMalaysia School of Foundation Studies Xiamen University Malaysia43900 SepangSelangorMalaysia Forest Research Centre Sabah Forestry Department90009 SandakanSabahMalaysia Centre for Environmental Biology and Ecosystem Studies National Institute for Environmental Studies(NIES)OnogawaTsukuba 305-0053Japan Secretariat of International Society for Mangrove Ecosystems(ISME) Faculty of AgricultureUniversity of the RyukyusOkinawa 903-0129Japan

Flavonoids are by far the most dominant class of phenolic compounds isolated from Morus alba leaves(MAL). Other classes of compounds are benzofurans, phenolic acids, alkaloids, coumarins, chalcones and stilbenes. Major flavonoids are kuwanons, moracinflavans, moragrols and morkotins. Other major compounds include moracins(benzofurans), caffeoylquinic acids(phenolic acids) and morachalcones(chalcones). Research on the anticancer properties of MAL entailed in vitro and in vivo cytotoxicity of extracts or isolated compounds. Flavonoids, benzofurans, chalcones and alkaloids are classes of compounds from MAL that have been found to be cytotoxic towards human cancer cell lines. Further studies on the phytochemistry and anticancer of MAL are suggested. Sources of information were Pub Med,Pub Med Central, Science Direct, Google, Google Scholar, J-Stage, Pub Chem and China National Knowledge Infrastructure.

关键词： Flavonoids Benzofurans Cytotoxic Moracins Morachalcones Chalcomoracin

Comparison of debris collision fluxes for the international space station

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Journal of Beijing Institute of Technology 2016年第S2期25卷 41-49页

作者：周威萍 KEN chan National Astronomical Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences

The calculation of the debris fluxes experienced by the international space station(ISS)traversing through a cloud of orbiting debris is *** cases of modeling the orbits of the debris within a thin spherical shell straddling the ISS orbit are considerded as follows:the debris objects have " almost" circular orbits;all actual elliptical debris orbits are *** accounts for the actual debris population with various inclined orbits,thus resulting in a variation of debris density with *** number of debris objects per year is compared to that obtained by the NASA ORDEM 3.0 Model.

关键词： collision probability number of collision space orbits space debris