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An Inequality for the Perron Pair of an Irreducible and Symmetric Nonnegative Tensor with Application

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Journal of the Operations Research Society of China 2017年第1期5卷 65-82页

作者： Mao-Lin che yi-Min Wei School of Mathematical Sciences Fudan UniversityShanghai 200433China School of Mathematical Sciences and Shanghai Key Laboratory of Contemporary Applied Mathematics Fudan UniversityShanghai 200433China

The main purpose of this paper is to consider the Perron pair of an irreducible and symmetric nonnegative tensor and the smallest eigenvalue of an irreducible and symmetric nonsingular *** analyze the analytical property of an algebraic simple eigenvalue of symmetric *** also derive an inequality about the Perron pair of nonnegative tensors based on plane stochastic *** finally consider the perturbation of the smallest eigenvalue of nonsingular M-tensors and design a strategy to compute its smallest *** verify our results via random numerical examples.

关键词： Nonnegative tensor Symmetric tensor Irreducible tensor M-Tensor H-Eigenpair An algebraic simple eigenvalue The Perron pair The smallest eigenvalue Perturbation

Discrete element modeling of sand behavior in a biaxial shear test

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第9期9卷 1176-1183页

作者： Zhi-yi HUANG Zhong-xuan YANG Zhen-yu WANG Department of Civil Engineering Zhejiang University Hangzhou 310027 China MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310027 China Department of Civil Engineering The University of Hong Kong Hong Kong China

The mechanical behavior of sand is very complex, and depends on factors including confining pressure, density, and drainage condition. A soil mass can be contractive or dilative when subjected to shear loading, and eventually reaches an ultimate state, referred to as the critical state in soil mechanics. Conventional approach to explore the mechanical behavior of sand mainly relies on the experimental tests in laboratory. This paper gives an alternative view to this subject using discrete element method (DEM), which has attracted much attention in recent years. The implementation of the DEM is carried out by a series of numerical tests on granular assemblies with varying initial densities and confining pressures, under different test configurations. The results demonstrate that such numerical simulations can produce correct responses of the sand behavior in general, including the critical state response, as compared to experimental observations. In addition, the DEM can further provide details of the microstructure evolutions during shearing processes, and the resulting induced anisotropy can be fully captured and quantified in the particle scale.

关键词： Granular soil behavior Critical state Microstructure Discrete element method (DEM)

Total-factor energy efficiency of ten major global energy-consuming countries

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Journal of Environmental Sciences 2024年第3期137卷 41-52页

作者： xuan Wang Yonglong Lu Chunci chen Xiaojie yi Haotian Cui State Key Laboratory of Urban and Regional Ecology Research Centre for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China State Key Laboratory of Marine Environmental Science and Key Laboratory of the Ministry of Education for Coastal Wetland Ecosystems College of the Environment and EcologyXiamen UniversityFujian 361102China University of Chinese Academy of Sciences Beijing 100049China

Improving energy efficiency is regarded as a key path to tackling global warming and achieving the Sustainable Development Goals(SDGs).In 2020,the energy consumption of the world's ten major energy-consuming countries accounted for 66.8%of the global *** paper applied data envelopment analysis(DEA)to calculate these ten major energyconsuming countries'total-factor energy efficiency(TFEE)at national and sectoral levels from 2001-2020,and explored the infuencing factors of total-factor energy efficiency with the Tobit regression *** results showed significant difference in the ten countries'energy *** United States and Germany topped the list for total-factor energy efficiency,while China and India were at the ***,the energy efficiency of the industrial subsector has increased significantly over the past two decades,while that of the other subsectors has been relatively *** industrial structure upgrading,per capita GDP,energy consumption structure,and foreign direct investment had significant impacts on energy efficiency with national *** consumption structure and GDP per capita were determinative factors of energy efficiency.

关键词： Total-factor energy efficiency SBM-UN model Major energy-consuming country Carbon emission reduction

Dual-phase change composites with temperature control and low infrared emissivity properties fabricated by electrospinning for infrared stealth and thermal camouflage

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Science China Technological Sciences 2024年第12期67卷 3755-3765页

作者： LI ChuanChang che PanPan XIE BaoShan ZENG XiaoLiang LONG yi Key Laboratory of Renewable Energy Electric-Technology of Hunan Province School of Energy and Power EngineeringChangsha University of Science and Technology State Key Laboratory of Disaster Prevention & Reduction for Power Grid Changsha University of Science & Technology Shenzhen Institute of Advanced Electronic Materials Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Department of Electronic Engineering The Chinese University of Hong Kong

Infrared stealth technology allows targets to evade detection by thermal infrared detection and plays an important role in the defense industry and military. However, current research and development of infrared stealth materials focuses only on reducing infrared emissivity or controlling the surface temperature of an object, and few studies combine the two. Therefore, in this paper,vanadium dioxide/polyethylene glycol/polyacrylonitrile（VO2/PEG/PAN） composite nanofibrous films were fabricated using the electrospinning technique with PAN as the matrix, PEG as the temperature-regulated material and VO2as the infrared emissivity material. The composite nanofibrous films not only possessed excellent thermal stability and mechanical properties but also had good thermal regulation and adjustable infrared emissivity. The latent heat value of the first phase change was 40.42 J g-1and the latent heat value of the second phase change was 4.27 J g-1when the content of VO2was 40wt%; more importantly, the infrared emissivity was 0.16 at 90°C. Therefore, the composite nanofibrous films could help achieve good infrared stealth and thermal camouflage performance for high-temperature targets through effective thermal buffering and infrared emissivity modulation capabilities. With the characteristics of ultra-lightweight, flexibility, foldability, adjustable shape, strong thermal stability,excellent mechanical properties, thermal self-regulation, and adjustable infrared emissivity, the prepared VO2/PEG/PAN composite nanofibrous films present great potential for application in infrared stealth and thermal camouflage of new military equipment.

关键词： phase change thermal camouflage electrospinning vanadium dioxide infrared stealth

Experiments on Channel Evolution due to Dam Removal in Taiwan

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Journal of Mountain Science 2014年第6期11卷 1396-1405页

作者： WANG Hsiao-Wen cheNG ying-che LIN Chung-yi Department of Hydraulic and Ocean Engineering National Cheng Kung University

Due to safety concerns and habitat restoration for landlocked salmon,a 13-m high check dam on Chijiawan Creek was removed in late May 2011 in *** conducted experiments to understand channel evolution of different *** further compared our experimental results of riverbed elevation changes with the analytical solutions derived from the diffusion equation and field dynamics as well after the creek experienced the first flood *** results indicated that magnitude of discharges and notch size are dominant factors in resulting channel *** the largest differences between grain size distribution are associated with discharge,the largest differences in net change in upstream volume are associated with notch *** the theoretical equation could help understand the channel change after dam removal,it only explained the evolution closer to the *** physical experiments,on the other hand,provided insights especially with regard to comparing alternative proposed management *** discrepancies between predicted and actual outcome highlight more needed inputs for future dam-removal assessments.

关键词： Dam removal Physical Experiments Channel Evolution Grain size distribution Riverbed elevation

Feasibility Study on Fabrication of Geopolymer Bricks by Wasted Grinding Wheel at Room Temperature

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Journal of Renewable Materials 2020年第12期8卷 1657-1670页

作者： yi-che Hsieh Ta-Wui cheng Chia-Ho Wu Department of Materials and Mineral Resources Engineering National Taipei University of TechnologyTaipei10608Taiwan Institute of Mineral Resources Engineering National Taipei University of TechnologyTaipei10608Taiwan

In this study,the feasibility of producing eco-friendly bricks by using geopolymer technology and a waste grinding wheel(WGW)from the grinding wheel industries was ***,in order to meet industrial needs,for instance,in Taiwan,approximately 500,000 grinding wheels are used *** is,a large number of“waste”grinding wheels are ***,few studies have been conducted on the use of WGWs as raw materials in geopolymer *** use of geopolymer technology to form bricks can avoid the utilization of clay and cement and even prevent the use of a high-temperature process in ***,it can decrease CO_(2) emission and energy consumption and thus,protect the *** this study,the following three major factors were considered:press-forming pressure(70 and 100 kgf/cm2),NaOH molar concentration(2 and 4M),and the ratio of binder fineaggregate(1:3,1:4,and 1:5).Under these conditions,the specimens were tested using the compressive strength test,water absorption test,microstructure analysis,a freezing–thawing test and toxicity characteristic leaching procedure *** optimal formulation was composed of 1:4 binder fine-aggregate ratio,4M NaOH concentration,and 100-kgf/cm2 ***,we used a WGW and achieved a compressive strength of 50.6 MPa after 28 days,which was greater than 32 MPa and conformed to the Grade A brick standard of National Standards of the Republic of China(13295).In conclusion,this brick fabrication method based on geopolymer technology was not only beneficial to the environment but also improved the efficiency of reutilizing WGW.

关键词： Geopolymer waste grinding wheel geopolymer bricks

Adsorption desulfurization and weak competitive behavior from 1-hexene over cesium-exchanged Y zeolites(CsY)

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Journal of Energy chemistry 2018年第1期27卷 271-277页

作者： Xiaojuan Liu Dezhi yi Yuanyuan Cui Li Shi xuan Meng Research Center of Petroleum Processing East China University of Science and Technology

The systematic research about the adsorption desulfurization and competitive behavior from 1-hexene over cesium-exchanged Y zeolites has been investigated. The structural properties of the adsorbents were characterized by X-ray diffraction（XRD）, N_2 sorption（BET） and thermal analysis（TGA）. The effects of calcination temperature, calcination atmosphere, and adsorption temperature were studied by the dynamic and static tests. The competitive adsorption mechanisms between thiophene and 1-hexene were studied by in-situ Fourier transform infrared spectroscopy（in-situ FTIR） and temperature-programmed desorption（TPD）. CsY adsorbents exhibited high selectivity for thiophene even when a large amount of olefins ***-situ FTIR spectra of thiophene and 1-hexene adsorption indicated that both thiophene and 1-hexene were mainly adsorbed on CsY via π-complexation. The higher desorption activated energy and higher adsorption heat of thiophene than 1-hexene obtained by thiophene-TPD and hexene-TPD has revealed that thiophene is adsorbed more strongly in CsY adsorbents than 1-hexene.

关键词： 1-hexeneCsY Adsorption desulfurization Thiophene Mechanism

Response of fine particulate matter to reductions in anthropogenic emissions in Beijing during the 2014 Asia–Pacific Economic Cooperation summit

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Atmospheric and Oceanic Science Letters 2016年第6期9卷 411-419页

作者： GU yi-xuan LIAO Hong State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric chemistry Institute of Atmospheric PhysicsChinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences School of Environmental Science and Engineering Nanjing University of Information Science &Technology

The nested-grid capability of the global chemical transport model GEOS-chem, with a horizontal resolution of 1/4°× 5/16° （latitude x longitude）, was used to identify the chemical species whose reductions made the largest contributions to decreases in PM2.s concentrations （fine particulate matter, diameter 〈 2.5μm, defined in this study as the sum of sulfate, nitrate, ammonium, black carbon, and organic carbon aerosols） in Beijing during the 2014 Asia-Pacific Economic Cooperation （APEC） summit. A number of numerical experiments were carried out for the period 15 October-29 November 2014. The model reproduced the observed daily variations of concentrations of PM2.s and gas-phase species （carbon monoxide, nitrogen dioxide, and sulfur dioxide）. Simulated PM2.s concentrations decreased by 55.9%-58.5% during the APEC period, compared to other periods in October and November 2014, which agreed closely with measurements. Sensitivity results showed that emissions control measures regarding nitrogen oxides and organic carbon over North China led to the largest reductions in PM2.s concentrations in Beijing during the APEC summit, which led to overall reductions in the PM2.5 concentration of Beijing by 5.7% and 4.6%, respectively. The control of ammonia emissions was found to be able to greatly reduce PM2.5 concentrations in the whole of North China during the APEC meeting.

关键词： Fine particulate matter emissions reduction Asia-Pacifc EconomicCooperation Beijing GEOS-chem

Luminescence properties of nitrogen-rich Ca-SiAlON:Eu2+ phosphors prepared by freeze-drying assisted combustion synthesis

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International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 687-692页

作者： Zhang-lin chen Kai Liu xuan-yi Yuan Ke-xin chen Beijing Key Laboratory of Optoelectronic Functional Materials&Micro-nano Devices Department of PhysicsRenmin University of ChinaBeijing 100872China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100872China

Nitrogen-rich Eu2+-doped Ca-α-SiAlON phosphors(Cam/2-xSi12-m-nAlm+nOnN16-n:xEu) were synthesized by a freeze-drying assisted combustion synthesis(CS) route. Fast-synthesized products with high purity and uniform particle morphology were confirmed by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The analysis of lattice parameters by comparison with empirical equations showed that the as-prepared phosphors had low oxygen content. A series of samples were prepared according to the stoichiometry of Cam/2-0.08Si12-mAlmN16:0.08 Eu for further research. The influences of m value on the luminescence properties were investigated in detail. As m increased, a redshift phenomenon was observed in both the excitation and emission spectra. First-principle electronic structure calculations showed that the 3d energy level of Ca played an important role in the occurrence of the redshift phenomenon.

关键词： freeze-drying combustion synthesis phosphors powder fluorescence spectra first-principle calculation