High-accuracy position monitoring of key components is required for modern synchrotron sources,such as free-electron lasers and diffraction-limited storage rings.Although various position monitoring sensors have been ...High-accuracy position monitoring of key components is required for modern synchrotron sources,such as free-electron lasers and diffraction-limited storage rings.Although various position monitoring sensors have been adopted to monitor the displacement of key components in each direction in real time,these monitoring systems are usually based on their own coordinate system.Data from such systems are meaningful when evaluating and examining the data from each positioning monitoring system in a unified coordinate system.This paper presents the design and construction of a multi-sensor position monitoring system(MPMS).A hydrostatic levelling system,a wire position sensor(WPS) and a tiltmeter are fixed to a stainless steel plate that has been calibrated by a coordinate-measurement machine.Several plates form the MPMS.The system must compensate for the sag of the stretched wires so that the WPSs create a straight line.The method of the coordinate transformation from the sensor coordinate system to the MPMS coordinate system was thoroughly studied.An experimental MPMS that includes five plates was setup in a 20-m tunnel,and a validation study to verify fully the feasibility of the MPMS was performed.展开更多
Using the coordinate transformation method,we study the polynomial solutions of the Schrodinger equationwith position-dependent mass (PDM).The explicit expressions for the potentials,energy eigenvalues,and eigenfuncti...Using the coordinate transformation method,we study the polynomial solutions of the Schrodinger equationwith position-dependent mass (PDM).The explicit expressions for the potentials,energy eigenvalues,and eigenfunctionsof the systems are given.The issues related to normalization of the wavefunctions and Hermiticity of the Hamiltonianare also analyzed.展开更多
By using coordinate transformation method,this paper obtains an useful equation of designing meta-material cloaks embedded in anisotropic medium.This equation is the generalization of what was introduced early by Pend...By using coordinate transformation method,this paper obtains an useful equation of designing meta-material cloaks embedded in anisotropic medium.This equation is the generalization of what was introduced early by Pendry et al(2006 Science 312 1780) and can be more widely used.As an example of its applications,this paper deduces the material parameter equation for cylinder cloaks embedded in anisotropic medium,and then offers the numerical simulation.The results show that such a cylinder cloak has perfect cloaking performance and therefore verifies the method proposed in this paper.展开更多
River ice is a natural phenomenon in cold regions,influenced by meteorology,geomorphology,and hydraulic conditions.River ice processes involve complex interactions between hydrodynamic,mechanical,and thermal processes...River ice is a natural phenomenon in cold regions,influenced by meteorology,geomorphology,and hydraulic conditions.River ice processes involve complex interactions between hydrodynamic,mechanical,and thermal processes,and they are also influenced by weather and hydrologic conditions.Because natural rivers are serpentine,with bends,narrows,and straight reaches,the commonly-used one-dimensional river ice models and two-dimensional models based on the rectangular Cartesian coordinates are incapable of simulating the physical phenomena accurately.In order to accurately simulate the complicated river geometry and overcome the difficulties of numerical simulation resulting from both complex boundaries and differences between length and width scales,a two-dimensional river ice numerical model based on a boundary-fitted coordinate transformation method was developed.The presented model considers the influence of the frazil ice accumulation under ice cover and the shape of the leading edge of ice cover during the freezing process.The model is capable of determining the velocity field,the distribution of water temperature,the concentration distribution of frazil ice,the transport of floating ice,the progression,stability,and thawing of ice cover,and the transport,accumulation,and erosion of ice under ice cover.A MacCormack scheme was used to solve the equations numerically.The model was validated with field observations from the Hequ Reach of the Yellow River.Comparison of simulation results with field data indicates that the model is capable of simulating the river ice process with high accuracy.展开更多
五零能模式材料是一种新型人工超材料,特征为其弹性模量矩阵的6个特征值中5个为零,可用等效体积模量来描述,表现出类似流体的性质,可被应用于声学隐声斗篷的设计中.然而,根据Norris A N[1]提出的理论,设计五零能模式材料时,与应用变换...五零能模式材料是一种新型人工超材料,特征为其弹性模量矩阵的6个特征值中5个为零,可用等效体积模量来描述,表现出类似流体的性质,可被应用于声学隐声斗篷的设计中.然而,根据Norris A N[1]提出的理论,设计五零能模式材料时,与应用变换声学方法设计一般声学人工超材料不同,要求其满足一非线性偏微分方程约束.论文利用非线性有限元的完全拉格朗日方法,推导了这一偏微分方程的弱形式,并给出了相应的非线性有限元计算列式,以及迭代求解的具体算法.最后,给出了五零能摸式材料设计的二维和三维坐标变换数值算例.展开更多
基金supported by the National Natural Science Foundation of China(No.11275192)the upgrade project of Hefei Light Source
文摘High-accuracy position monitoring of key components is required for modern synchrotron sources,such as free-electron lasers and diffraction-limited storage rings.Although various position monitoring sensors have been adopted to monitor the displacement of key components in each direction in real time,these monitoring systems are usually based on their own coordinate system.Data from such systems are meaningful when evaluating and examining the data from each positioning monitoring system in a unified coordinate system.This paper presents the design and construction of a multi-sensor position monitoring system(MPMS).A hydrostatic levelling system,a wire position sensor(WPS) and a tiltmeter are fixed to a stainless steel plate that has been calibrated by a coordinate-measurement machine.Several plates form the MPMS.The system must compensate for the sag of the stretched wires so that the WPSs create a straight line.The method of the coordinate transformation from the sensor coordinate system to the MPMS coordinate system was thoroughly studied.An experimental MPMS that includes five plates was setup in a 20-m tunnel,and a validation study to verify fully the feasibility of the MPMS was performed.
文摘Using the coordinate transformation method,we study the polynomial solutions of the Schrodinger equationwith position-dependent mass (PDM).The explicit expressions for the potentials,energy eigenvalues,and eigenfunctionsof the systems are given.The issues related to normalization of the wavefunctions and Hermiticity of the Hamiltonianare also analyzed.
基金supported by the National Natural Science Foundation of China (Grant Nos 50632030 and 10474077)the 973-Project of the Ministry of Science and Technology of China (Grant No 2002CB613307)The Innovation Funds of the College of Science,Air Force University of Engineering
文摘By using coordinate transformation method,this paper obtains an useful equation of designing meta-material cloaks embedded in anisotropic medium.This equation is the generalization of what was introduced early by Pendry et al(2006 Science 312 1780) and can be more widely used.As an example of its applications,this paper deduces the material parameter equation for cylinder cloaks embedded in anisotropic medium,and then offers the numerical simulation.The results show that such a cylinder cloak has perfect cloaking performance and therefore verifies the method proposed in this paper.
基金supported by the National Natural Science Foundation of China(Grant No.50579030)
文摘River ice is a natural phenomenon in cold regions,influenced by meteorology,geomorphology,and hydraulic conditions.River ice processes involve complex interactions between hydrodynamic,mechanical,and thermal processes,and they are also influenced by weather and hydrologic conditions.Because natural rivers are serpentine,with bends,narrows,and straight reaches,the commonly-used one-dimensional river ice models and two-dimensional models based on the rectangular Cartesian coordinates are incapable of simulating the physical phenomena accurately.In order to accurately simulate the complicated river geometry and overcome the difficulties of numerical simulation resulting from both complex boundaries and differences between length and width scales,a two-dimensional river ice numerical model based on a boundary-fitted coordinate transformation method was developed.The presented model considers the influence of the frazil ice accumulation under ice cover and the shape of the leading edge of ice cover during the freezing process.The model is capable of determining the velocity field,the distribution of water temperature,the concentration distribution of frazil ice,the transport of floating ice,the progression,stability,and thawing of ice cover,and the transport,accumulation,and erosion of ice under ice cover.A MacCormack scheme was used to solve the equations numerically.The model was validated with field observations from the Hequ Reach of the Yellow River.Comparison of simulation results with field data indicates that the model is capable of simulating the river ice process with high accuracy.
文摘五零能模式材料是一种新型人工超材料,特征为其弹性模量矩阵的6个特征值中5个为零,可用等效体积模量来描述,表现出类似流体的性质,可被应用于声学隐声斗篷的设计中.然而,根据Norris A N[1]提出的理论,设计五零能模式材料时,与应用变换声学方法设计一般声学人工超材料不同,要求其满足一非线性偏微分方程约束.论文利用非线性有限元的完全拉格朗日方法,推导了这一偏微分方程的弱形式,并给出了相应的非线性有限元计算列式,以及迭代求解的具体算法.最后,给出了五零能摸式材料设计的二维和三维坐标变换数值算例.
