The properties of the transfer-matrix of U(1) lattice gauge theory in the Fourier basis are explored.Among other statements it is shown:(i) the transfer-matrix is block-diagonal,(ii) all consisting vectors of a block ...The properties of the transfer-matrix of U(1) lattice gauge theory in the Fourier basis are explored.Among other statements it is shown:(i) the transfer-matrix is block-diagonal,(ii) all consisting vectors of a block are known based on an arbitrary block vector,(iii) the ground-state belongs to the zero-mode’s block.The emergence of maximum-points in matrix-elements as functions of the gauge coupling is clarified.Based on explicit expressions for the matrix-elements we present numerical results as tests of our statements.展开更多
Surface spin waves in a semi-infinite magnetre super lattice with a single-ion uniaxial anisotropy are investigated through the transfer mafrix method.The dispersion equations of surface spin wavs are obfained.We find...Surface spin waves in a semi-infinite magnetre super lattice with a single-ion uniaxial anisotropy are investigated through the transfer mafrix method.The dispersion equations of surface spin wavs are obfained.We find that not all the magnetic superlattice structures can excite the surface spin waves,and that the anisotropy term need not be favorable to the excitation of surface spin wavs,but surely influences the values of the energy of the excited surface spin waves.展开更多
目的塔里木河流域是我国典型干旱、生态脆弱区,系统研究其生境质量时空演变规律,对揭示干旱区生态机理、促进流域屏障建设及可持续发展具重要科学与实践价值。方法基于土地利用数据,采用土地利用转移矩阵和InVEST(Integrated Valuation ...目的塔里木河流域是我国典型干旱、生态脆弱区,系统研究其生境质量时空演变规律,对揭示干旱区生态机理、促进流域屏障建设及可持续发展具重要科学与实践价值。方法基于土地利用数据,采用土地利用转移矩阵和InVEST(Integrated Valuation of Ecosystem Services and Trade-offs)模型对研究区土地利用和生境质量变化进行分析,并结合地理探测器(Geodetector)定量分析该区域生境质量变化的驱动因素。结果塔里木河流域耕地和建设用地扩张趋势突出,土地利用类型变化主要为草地和未利用地之间的相互转化以及草地向耕地的单向转入;流域整体生境质量偏差,2000~2020年间,生境质量指数由0.386下降为0.366,区域整体平均生境退化度升高;由2000~2020年的单因子探测结果可知,坡度、气温、DEM和降水对生境质量空间分异的解释力强度较大;GDP对该区域的生境质量空间分布解释力较小;由2000~2020年的交互因子探测结果可知,双因子交互作用的解释力均大于单因子作用的解释力。结论研究成果揭示了塔里木河流域生境质量的时空变化过程,阐明了其变化由自然因子主导、并与人文因子交互增强共同驱动的内在机制,可为大尺度流域生态脆弱区的生境质量评估与保护策略制定提供更具针对性的科学依据。展开更多
【目的】为准确高效地分析多轴双环磁力齿轮(Multishaft Double Ring-Plate Magnetic Gears,MDRMGs)的磁力与动力学特性,改善摆线式磁力齿轮(Cycloidal Permanent Magnetic Gear,CPMG)转臂轴承工况并延长使用寿命,将磁力齿轮与机械式环...【目的】为准确高效地分析多轴双环磁力齿轮(Multishaft Double Ring-Plate Magnetic Gears,MDRMGs)的磁力与动力学特性,改善摆线式磁力齿轮(Cycloidal Permanent Magnetic Gear,CPMG)转臂轴承工况并延长使用寿命,将磁力齿轮与机械式环板齿轮相结合,设计了一种多轴双环磁力齿轮传动结构。【方法】提出一种磁场单元归类法,进而建立了高效且计及端部漏磁效应的气隙磁场及静态转矩数理模型;同时,基于Riccati传递矩阵法,建立了MDRMG偏心轴转子系统动力学模型。【结果】将磁场单元归类法与有限元法进行对比,发现二者所得的磁密度及磁力结果高度一致,但磁场单元归类法的计算耗时更短;分析还发现,环板间距的变化会影响磁场单元的归类计算及动力学模型中的集总参数,使得MDRMG的静态磁力转矩随环板间距的增加而增加,偏心轴的临界转速随环板间距的增加而减小。磁场单元归类法能够高效且准确地分析MDRMG的气隙磁场及转矩特性;同时,环板间距对MDRMGs的磁场和动力学性能有一定影响。展开更多
基金Supported by the Research Council of the Alzahra University
文摘The properties of the transfer-matrix of U(1) lattice gauge theory in the Fourier basis are explored.Among other statements it is shown:(i) the transfer-matrix is block-diagonal,(ii) all consisting vectors of a block are known based on an arbitrary block vector,(iii) the ground-state belongs to the zero-mode’s block.The emergence of maximum-points in matrix-elements as functions of the gauge coupling is clarified.Based on explicit expressions for the matrix-elements we present numerical results as tests of our statements.
文摘Surface spin waves in a semi-infinite magnetre super lattice with a single-ion uniaxial anisotropy are investigated through the transfer mafrix method.The dispersion equations of surface spin wavs are obfained.We find that not all the magnetic superlattice structures can excite the surface spin waves,and that the anisotropy term need not be favorable to the excitation of surface spin wavs,but surely influences the values of the energy of the excited surface spin waves.
文摘目的塔里木河流域是我国典型干旱、生态脆弱区,系统研究其生境质量时空演变规律,对揭示干旱区生态机理、促进流域屏障建设及可持续发展具重要科学与实践价值。方法基于土地利用数据,采用土地利用转移矩阵和InVEST(Integrated Valuation of Ecosystem Services and Trade-offs)模型对研究区土地利用和生境质量变化进行分析,并结合地理探测器(Geodetector)定量分析该区域生境质量变化的驱动因素。结果塔里木河流域耕地和建设用地扩张趋势突出,土地利用类型变化主要为草地和未利用地之间的相互转化以及草地向耕地的单向转入;流域整体生境质量偏差,2000~2020年间,生境质量指数由0.386下降为0.366,区域整体平均生境退化度升高;由2000~2020年的单因子探测结果可知,坡度、气温、DEM和降水对生境质量空间分异的解释力强度较大;GDP对该区域的生境质量空间分布解释力较小;由2000~2020年的交互因子探测结果可知,双因子交互作用的解释力均大于单因子作用的解释力。结论研究成果揭示了塔里木河流域生境质量的时空变化过程,阐明了其变化由自然因子主导、并与人文因子交互增强共同驱动的内在机制,可为大尺度流域生态脆弱区的生境质量评估与保护策略制定提供更具针对性的科学依据。
文摘【目的】为准确高效地分析多轴双环磁力齿轮(Multishaft Double Ring-Plate Magnetic Gears,MDRMGs)的磁力与动力学特性,改善摆线式磁力齿轮(Cycloidal Permanent Magnetic Gear,CPMG)转臂轴承工况并延长使用寿命,将磁力齿轮与机械式环板齿轮相结合,设计了一种多轴双环磁力齿轮传动结构。【方法】提出一种磁场单元归类法,进而建立了高效且计及端部漏磁效应的气隙磁场及静态转矩数理模型;同时,基于Riccati传递矩阵法,建立了MDRMG偏心轴转子系统动力学模型。【结果】将磁场单元归类法与有限元法进行对比,发现二者所得的磁密度及磁力结果高度一致,但磁场单元归类法的计算耗时更短;分析还发现,环板间距的变化会影响磁场单元的归类计算及动力学模型中的集总参数,使得MDRMG的静态磁力转矩随环板间距的增加而增加,偏心轴的临界转速随环板间距的增加而减小。磁场单元归类法能够高效且准确地分析MDRMG的气隙磁场及转矩特性;同时,环板间距对MDRMGs的磁场和动力学性能有一定影响。
