By the analysis for the vectors of a wave field in the cylindrical coordinate and Sommerfeld＇s identity as well as Green＇s functions of Stokes＇ solution pertaining the conventional elastic dynamic equation, the res...By the analysis for the vectors of a wave field in the cylindrical coordinate and Sommerfeld＇s identity as well as Green＇s functions of Stokes＇ solution pertaining the conventional elastic dynamic equation, the results of Green＇s function in an infinite space of an axisymmetric coordinate are shown in this paper. After employing a supplementary influence field and the boundary conditions in the free surface of a senti-space, the authors obtain the solutions of Green＇s function for Lamb＇s dynamic problem. Besides, the vertical displacement uzz and the radial displacement urz can match Lamb＇s previous results, and the solutions of the linear expansion source u^r and the linear torsional source uee are also given in the paper. The authors reveal that Green＇s function of Stokes＇ solution in the semi-space is a comprehensive form of solution expressing the dynamic Lamb＇s problem for various situations. It may benefit the investigation of deepening and development of Lamb＇s problems and solution for pertinent dynamic problems conveniently.展开更多
ZTE Corporation showcased a comprehensive range of its latest product portfolio at GSMA Mobile Asia Congress 2008 held November 18-20, 2008 in Macau, P. R. China.
Birefringence production of light by natural birefringent crystal has long been studied and well understood.Here,we develop a simple and comprehensive rigorous electromagnetic theory that allows one to build up the co...Birefringence production of light by natural birefringent crystal has long been studied and well understood.Here,we develop a simple and comprehensive rigorous electromagnetic theory that allows one to build up the complete picture about the optics of crystals in a friendly way.This theory not only yields the well-known refraction angle and index of ellipse for birefringence crystal,but also discloses many relevant physical and optical quantities that are rarely studied and less understood.We obtain the reflection and transmission coefficient for amplitude and intensity of light at the crystal surface under a given incident angle and show the electromagnetic field distribution within the crystal.We derive the wavefront and energy flux refraction angle of light and the corresponding phase and ray refractive index.We find big difference between them,where the phase refractive index satisfies the classical index of ellipse and Snell’s law,while the ray refractive index does not.Moreover,we disclose the explicit expressions for the zero-reflection Brewster angle and the critical angle for total internal reflection.For better concept demonstration,we take a weak birefringent crystal of lithium niobate and a strong birefringent crystal tellurium as examples and perform simple theoretical calculations.In addition,we perform experimental measurement upon z-cut lithium niobate plate and find excellent agreement between theory and experiment in regard to the Brewster angle.Our theoretical and experimental results can help to construct a clear and complete picture about light transport characteristics in birefringent crystals,and may greatly facilitate people to find rigorous solution to many light-matter interaction processes happening within birefringent crystals,e.g.,nonlinear optical interactions,with electromagnetic theory.展开更多
At present,there are still many problems in language teaching in rural primary schools,which will affect the quality of teaching if we don't pay much attention to them.This article focuses on the existing flaws in...At present,there are still many problems in language teaching in rural primary schools,which will affect the quality of teaching if we don't pay much attention to them.This article focuses on the existing flaws in current language teaching and provides some solutions.展开更多
Based on 20 students' self-report, this study presents the sources of listening comprehension anxiety:characteristics of listening comprehension, characteristics of listening materials and listening tasks, the soc...Based on 20 students' self-report, this study presents the sources of listening comprehension anxiety:characteristics of listening comprehension, characteristics of listening materials and listening tasks, the social/instructional factors and foreign language proficiency and listening level. Ways to alleviate anxiety are correspondingly involved.展开更多
基金supported by the National Natural Science Foundation of China(No.11172268)
文摘By the analysis for the vectors of a wave field in the cylindrical coordinate and Sommerfeld＇s identity as well as Green＇s functions of Stokes＇ solution pertaining the conventional elastic dynamic equation, the results of Green＇s function in an infinite space of an axisymmetric coordinate are shown in this paper. After employing a supplementary influence field and the boundary conditions in the free surface of a senti-space, the authors obtain the solutions of Green＇s function for Lamb＇s dynamic problem. Besides, the vertical displacement uzz and the radial displacement urz can match Lamb＇s previous results, and the solutions of the linear expansion source u^r and the linear torsional source uee are also given in the paper. The authors reveal that Green＇s function of Stokes＇ solution in the semi-space is a comprehensive form of solution expressing the dynamic Lamb＇s problem for various situations. It may benefit the investigation of deepening and development of Lamb＇s problems and solution for pertinent dynamic problems conveniently.
文摘ZTE Corporation showcased a comprehensive range of its latest product portfolio at GSMA Mobile Asia Congress 2008 held November 18-20, 2008 in Macau, P. R. China.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFA 0306200)the National Natural Science Foundation of China(Grant No.11974119)+1 种基金the Science and Technology Project of Guangdong Province,China(Grant No.2020B010190001)the Guangdong Innovative and Entrepreneurial Research Team Program(Grant No.2016ZT06C594)。
文摘Birefringence production of light by natural birefringent crystal has long been studied and well understood.Here,we develop a simple and comprehensive rigorous electromagnetic theory that allows one to build up the complete picture about the optics of crystals in a friendly way.This theory not only yields the well-known refraction angle and index of ellipse for birefringence crystal,but also discloses many relevant physical and optical quantities that are rarely studied and less understood.We obtain the reflection and transmission coefficient for amplitude and intensity of light at the crystal surface under a given incident angle and show the electromagnetic field distribution within the crystal.We derive the wavefront and energy flux refraction angle of light and the corresponding phase and ray refractive index.We find big difference between them,where the phase refractive index satisfies the classical index of ellipse and Snell’s law,while the ray refractive index does not.Moreover,we disclose the explicit expressions for the zero-reflection Brewster angle and the critical angle for total internal reflection.For better concept demonstration,we take a weak birefringent crystal of lithium niobate and a strong birefringent crystal tellurium as examples and perform simple theoretical calculations.In addition,we perform experimental measurement upon z-cut lithium niobate plate and find excellent agreement between theory and experiment in regard to the Brewster angle.Our theoretical and experimental results can help to construct a clear and complete picture about light transport characteristics in birefringent crystals,and may greatly facilitate people to find rigorous solution to many light-matter interaction processes happening within birefringent crystals,e.g.,nonlinear optical interactions,with electromagnetic theory.
文摘At present,there are still many problems in language teaching in rural primary schools,which will affect the quality of teaching if we don't pay much attention to them.This article focuses on the existing flaws in current language teaching and provides some solutions.
文摘Based on 20 students' self-report, this study presents the sources of listening comprehension anxiety:characteristics of listening comprehension, characteristics of listening materials and listening tasks, the social/instructional factors and foreign language proficiency and listening level. Ways to alleviate anxiety are correspondingly involved.
