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Excluded Volumes of Anisotropic Convex Particles in Heterogeneous Media:Theoretical and Numerical Studies

Computers, materials & Continua 2016年第4期52卷 25-40页

作者： Wenxiang Xu Ganquan Yang Peng Lan Huaifa ma State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100048China Institute of Soft matter Mechanics College of Mechanics and MaterialsHohai UniversityNanjing 210098China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China College of Harbour Coastal and Offshore EngineeringHohai University

Understanding the excluded volume of anisotropic particle is of great importance in the evaluation of continuum percolation and random packing behaviors of soft/hard particle systems in heterogeneous disordered *** this work,we obtain the excluded volumes of several anisotropic convex particles including prolate spheroids,oblate spheroids,spherocylinders,and Platonic particles,using theoretical and numerical *** to the second virial coefficient,we first present a theoretical scheme for determining the excluded volumes of anisotropic ***,the mean tangent diameters of anisotropic convex particles are formulated by the quantitative ***,Monte Carlo simulations are demonstrated to numerically evaluate the excluded *** theoretical results of the dimensionless excluded volume are thereafter compared with that of the numerical results to verify the validity of the theoretical *** further investigate the dependence of the dimensionless excluded volume on the geometric characteristics of anisotropic particles based on the proposed theoretical and numerical *** show that the dimensionless excluded volume mainly relies on the shape and surface information of anisotropic *** developed theoretical and numerical schemes can provide theoretical insights into the percolation threshold and packing density of soft/hard anisotropic particle systems in heterogeneous materials,physics,and chemistry fields.

关键词： Excluded volume Convex particle Percolation Random packing Theory Monte carlo simulation

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Theoretical analysis on expansion mechanism in carbon dioxide expander

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Science China(Technological Sciences) 2011年第6期54卷 1469-1474页

作者： TIAN Hua ma YiTai LI MinXia ZHANG MeiLan Thermal Energy Research Institute Tianjin UniversiO Tianjin 300072 China

The expansion mechanism inside carbon dioxide expander is analyzed theoretically in this *** mechanism analysis of metastable equilibrium indicates that there is a potential barrier during phase change *** is to say energy is required to overcome the potential barrier when the new interface is formed from primary *** superheat of liquid is the impetus of phase change and has an exponential decrease with the increase of the saturated temperature of *** analysis also indicates that there is a critical radius during the phase change *** bubble will grow up when its radius is larger than the critical value,otherwise,will *** considering the metastable phase change,calculation of P and V during expansion process indicates that the phase-change will be delayed with the decline of pressure,which is called lag *** phase-change delay time decreases with the increase of initial *** the initial temperature is close to the critical temperature,the delay time is close to *** phase-change delay brings energy losses,which decrease with the increase of initial temperature and its decrease ratio also has a decrease *** the initial pressure is 10 MPa,the energy loss will be 1.06 W with an initial temperature of 10℃ while 0.34 W with that of 20℃.

关键词： expansion mechanism carbon dioxide expander potential barrier superheat degree phase-change delay

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Multi-parameter Triebel-Lizorkin and Besov Spaces Associated with Flag Singular Integrals

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Acta mathematica Sinica,English Series 2010年第4期26卷 603-620页

作者： Yong diNG Guo Zhen LU Bo Lin ma Laboratory of mathematics and Complex Systems ( BNU) Ministry of Education P. R. China School of mathematics Beijing Normal University Beijing 100875 P. R. China Department of mathematics Wayne State University Detroit 48202 USA College of mathematics and Information Engineering Jiaxing University Jiaxing 314001 P. R. China

Though the theory of one-parameter Triebel-Lizorkin and Besov spaces has been very well developed in the past decades, the multi-parameter counterpart of such a theory is still absent. The main purpose of this paper is to develop a theory of multi-parameter Triebel-Lizorkin and Besov spaces using the discrete Littlewood-Paley-Stein analysis in the setting of implicit multi-parameter structure. It is motivated by the recent work of Han and Lu in which they established a satisfactory theory of multi-parameter Littlewood-Paley-Stein analysis and Hardy spaces associated with the flag singular integral operators studied by Muller-Ricci-Stein and Nagel-Ricci-Stein. We also prove the boundedness of flag singular integral operators on Triebel-Lizorkin space and Besov space. Our methods here can be applied to develop easily the theory of multi-parameter Triebel-Lizorkin and Besov spaces in the pure product setting.

关键词： flag singular integrals multiparameter Triebel-Lizorkin spaces discrete Calderdn repro- ducing formulas discrete Littlewood-Paley-Stein analysis

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Atlas Compatibility Transformation:A Normal manifold Learning Algorithm

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International Journal of Automation and computing 2015年第4期12卷 382-392页

作者： Zhong-Hua Hao Shi-Wei ma Fan Zhao School of Mechatronic Engineering and Automation Shanghai Key Laboratory of Power Station Automation TechnologyShanghai University

Over the past few years,nonlinear manifold learning has been widely exploited in data analysis and machine *** paper presents a novel manifold learning algorithm,named atlas compatibility transformation(ACT),It solves two problems which correspond to two key points in the manifold definition:how to chart a given manifold and how to align the patches to a global coordinate space based on *** the first problem,we divide the manifold into maximal linear patch(MLP) based on normal vector field of the *** the second problem,we align patches into an optimal global system by solving a generalized eigenvalue *** with the traditional method,the ACT could deal with noise datasets and fragment ***,the mappings between high dimensional space and low dimensional space are *** on both synthetic data and real-world data indicate the effection of the proposed algorithm.

关键词： Nonlinear dimensionality reduction manifold learning normal vector field maximal linear patch ambient space.

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Optimization of the MUSCL scheme by dispersion and dissipation

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Science China(Physics,Mechanics & Astronomy) 2012年第5期55卷 844-853页

作者： LENG Yan LI XinLiang FU DeXun ma YanWen The State Key Laboratory of High-temperature Gas Dynamics(LHD) Institute of MechanicsChinese Academy of SciencesBeijing 100190China The State Key Laboratory of Nonlinear Mechanics(LNM) Institute of MechanicsChinese Academy of SciencesBeijing 100190China

A second-order optimized monotonicity-preserving MUSCL scheme(OMUSCL2) is developed based on the dispersion and dissipation optimization and monotonicity-preserving *** new scheme(OMUSCL2) is simple in expression and is easy for use in CFD *** with the original second-order or third-order MUSCL scheme,the new scheme shows nearly the same CPU cost and higher resolution to shockwaves and small-scale *** new scheme has been tested through a set of one-dimensional and two-dimensional tests,including the Shu-Osher problem,the Sod problem,the Lax problem,the two-dimensional double mach reflection and the RAE2822 transonic airfoil *** numerical tests show that,compared with the original MUSCL schemes,the new scheme causes fewer dispersion and dissipation errors and produces higher resolution.

关键词： MUSCL scheme monotonicity-preserving resolution dissipation/dispersion error optimization

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Improved MPEG-4 High-Efficiency AAC With Variable-Length Soft-Decision Decoding of the Quantized Spectral Coefficients

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China Communications 2019年第10期16卷 65-82页

作者： Sai Han Hongbing ma Ping Zhang Tim Fingscheidt China United Network Communications Group Company Limited Beijing 100033China Beijing University of Posts and Telecommunications Beijing 100876China Institute for Communications Technology Technische Universitat BraunschweigBraunschweig 38106Germany

MPEG-4 High-Efficiency Advanced Audio Coding (HE-AAC) is designed for low bit rate applications, such as audio streaming in mobile communications. The HE-AAC audio codec offers a better coding efficiency since variable-length codes (VLCs) are adopted. However, HE-AAC has originally been designed for storage and error-free transmission conditions. For the transmission over bit error-prone channels, error propagation is a serious problem for the VLCs. Therefore, a robust HE-AAC decoder is desired, especially for mobile communications. In contrast to traditional hard-decision decoding, utilizing bit-wise channel reliability information, softdecision (SD) decoding has been known to offer better audio quality. In HE-AAC, the global gain parameter is coded with fixedlength codes (FLCs), while the scale factors and quantized spectral coefficients are coded with VLCs. In this work, we apply FL/SD decoding to the global gain parameter, VL/SD decoding to the parameters scale factors and quantized spectral coefficients. Especially, in order to apply VL/SD decoding to the quantized spectral coefficients, a new modified trellis representation in VL/SD decoding is proposed. An improved HE-AAC performance is clearly observed, with the support of both instrumental measurements and a subjective listening test.

关键词： variable-length soft-decision decoding HE-AAC trellis representation quantization spectral coefficients

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Deterioration of dynamic mechanical property of concrete with mineral admixtures under fatigue loading

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Science China(Technological Sciences) 2014年第10期57卷 1909-1916页

作者： ma KunLin XIE YouJun LONG GuangCheng TAN WenYong School of Civil Engineering Central South University National Engineering Laboratory for Construction Technology of High Speed Railway Key Laboratory of Engineering Structure of Heavy Railway Ministry of Education

The dynamic mechanical property of concrete is one of the key parameters,which greatly influences durability of infrastructures subjected to continuous heavy loading,such as girder and track slab of high-speed railway foundation *** paper reports serials of experiments designed to investigate the deterioration of dynamic mechanical properties of different concretes under fatigue loading *** parameters including relative dynamic elastic modulus(RDEM),relative dynamic shear modulus(RDSM),relative compressive strength(RCS)and water absorption(WA)of concrete were evaluated to assess the dynamic properties and microstructures of *** show that the fatigue stress levels and fatigue cycle durations significantly influence the dynamic mechanical properties of concrete including dynamic elastic modulus and dynamic shear *** of proper mineral admixture can improve the dynamic mechanical characteristics of concrete and increase its resistance against the fatigue loading *** the amount of mineral admixture in concrete constant,its dynamic mechanical property with fly ash is lower than that with fly ash and silica *** water absorption in concrete,which is an indirect parameter reflecting capillary porosity,increases evidently after bearing *** is a close correlation between the deterioration of dynamic mechanical property and the increasing of water absorption of *** indicates that the damage of microstructure of concrete subjected to fatigue loading is the indispensable reason for the decay of its dynamic mechanical performance.

关键词： concrete dynamic mechanical property fatigue loading mineral admixtures deterioration

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Population trends, threats, and conservation recommendations for waterbirds in China

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Avian Research 2018年第2期9卷 89-101页

作者： Xiaodan Wang Fenliang Kuang Kun Tan Zhijun ma Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Coastal Ecosystems Research Station of the Yangtze River Estuary Shanghai Institute of Eco-Chongming (SIEC) Fudan University

Background: China is one of the countries with abundant waterbird diversity. Over the past decades, China's waterbirds have suffered increasing threats from direct and indirect human activities. It is important to clarify the population trends of and threats to waterbirds as well as to put forward conservation ***: We collected data of population trends of a total of 260 waterbird species in China from Wetlands International database. We calculated the number of species with increasing, declining, stable, and unknown trends. We collected threatened levels of waterbirds from the Red List of China's Vertebrates(2016), which was compiled according to the IUCN criteria of threatened species. Based on literature review, we refined the major threats to the threatened waterbird species in ***: Of the total 260 waterbird species in China, 84 species(32.3%) exhibited declining, 35 species(13.5%) kept stable, and 16 species(6.2%) showed increasing trends. Population trends were unknown for 125 species(48.1%). There was no significant difference in population trends between the migratory(32.4% decline) and resident(31.8% decline) species or among waterbirds distributed exclusively along coasts(28.6% decline), inland(36.6% decline), and both coasts and inland(32.5% decline). A total of 38 species(15.1% of the total) were listed as threatened species and 27 species(10.8% of the total) Near Threatened species. Habitat loss was the major threat to waterbirds, with 32 of the total 38(84.2%) threatened species being affected. In addition, 73.7%(28 species), 71.1%(27 species), and 57.9%(22 species) of the threatened species were affected by human disturbance, environmental pollution, and illegal hunting, ***: We propose recommendations for waterbird conservation, including(1) strengthening conservation of nature wetlands and restoration of degraded wetlands,(2) enhancing public awareness on waterbird conservation,(3) improving the en

关键词： Conservation Habitats Population trend Threatened species Waterbirds Wetlands China

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Planetary Wave Reflection and Its Impact on Tropospheric Cold Weather over Asia during January 2008

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Advances in Atmospheric Sciences 2014年第4期31卷 851-862页

作者： Debashis NATH CHEN Wen WANG Lin ma Yin Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences

Reflection of stratospheric planetary waves and its impact on tropospheric cold weather over Asia during January 2008 were investigated by applying two dimensional Eliassen-Palm （EP） flux and three-dimensional Plumb wave activity *** planetary wave propagation can clearly be seen in the longitude-height and latitude-height sections of the Plumb wave activity flux and EP flux,respectively,when the stratospheric basic state is partially ***,a wave packet emanating from Baffin Island/coast of Labrador propagated eastward,equatorward and was reflected over Central Eurasia and parts of China,which in turn triggered the advection of cold wind from the northern part of the boreal forest regions and Siberia to the *** wide region of Central Eurasia and China experienced extreme cold weather during the second ten days of January 2008,whereas the extraordinary persistence of the event might have occurred due to an anomalous blocking high in the Urals-Siberia region.

关键词： planetary wave reflection reflective index advection blocking cold weather

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Improved spatio-SNR FGS video coding scheme using motion compensation on enhancement-layer

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Journal of Systems Engineering and Electronics 2006年第1期17卷 37-42页

作者： Jiang Tao Zhang Zhaoyang ma Ran Shi Xuli Dept. of Electronic & Information Engineering School of Communication Shanghai Univ. Shanghai 200072 P. R. China

MPEG-4 fine-granularity-scalable （FGS） technology is an effective solution to resolve the network bandwidth varying because FGS provides very fine granular SNR scalability. However, this scalability is obtained with sacrifice of coding efficiency. An one-loop FGS structure is presented based on motion compensation （MC ＋ FGS） to improve the coding efficiency of base FGS. Then it describes and discusses the hybrid spatial-SNR FGS （FGSS） structure that extends SNR scalability of FGS to spatial scalability （spatio-SNR scalability）. FGSS structure inherent the low coding efficiency of FGS structure. Combining MC ＋ FGS structure with FGSS structure, a structure of MC ＋ FGSS structure is obtained which acquires both structures＇ advantages and counteracts both structures＇ defects. Experimental results prove the MC＋ FGSS structure not only obtains fine granular spatio-SNR scalability, but also achieves high coding efficiency.

关键词： fine-granularity-scalable coding efficiency motion compensation spatial scalability MPEG-4.

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