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Table of Content

    20 July 2011 Volume 30 Issue 7
      
    第一段
    Questions and answers in the course of "methods of mathematical physics"
    . 2011, 30(7):  1-1. 
    Abstract ( 688 )   PDF (434KB) ( 377 )  
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    A series of questions,which are frequently emerged in the teaching of course of "methods of mathematical physics" but were rarely discussed in the textbooks,are listed.The answers or explanations are given in some detail.
    著者文摘
    Simplified method of calculating matrix elements of operators for harmonic oscillator
    . 2011, 30(7):  5-5. 
    Abstract ( 943 )   PDF (425KB) ( 342 )  
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    The problems of simply and directly computing the matrix elements of coordinate operator for the harmonic oscillator in both the number states and the coherent states representations are studied in detail,the explicit procedures are given and some issues related to the methods and procedures in the literatures are commented.
    Exact solution for a time-dependent magnetic resonance system and its quantum adiabatic approximation
    . 2011, 30(7):  9-9. 
    Abstract ( 760 )   PDF (281KB) ( 346 )  
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    By taking instantaneous eigenstates as complete base vectors,a traditional time-dependent magnetic Schrodinger equation is transformed into a second-order differential equation with constant coefficient which can be solved exactly.The difference between accurate solution and adiabatic solution of the magnetic resonance system is studied,our results show that the tunneling rate can not be always ignored.When the rotating magnetic field adjustable parameter θ is equal to 0.304 3π,the tunneling rate can be increased to the maximum value of 0.111 1.
    The magnetic field of a linear current and a wedge-shaped ferromagnetic material
    . 2011, 30(7):  12-12. 
    Abstract ( 729 )   PDF (346KB) ( 243 )  
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    The magnetic field of a linear current and a wedge-shaped ferromagnetic material is calculated by using the conformal mapping on the complex coordinate system of the complex number,and its magnetic vector distribution is obtained.The magnetic induction line maps are plotted by using the software MATLAB.
    Equivalent permittivity of core-shell structured ellipsoids
    . 2011, 30(7):  16-16. 
    Abstract ( 699 )   PDF (251KB) ( 472 )  
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    Based on the ellipsoidal coordinate,the spacial distribution of electric potential of a coated ellipsoid in a matrix is investigated by solving the Laplace equations under the boundary conditions.Furthermore,the equivalent permittivity of a coated ellipsoid is obtained.
    The kinematics equations of a free particle in the Schwarzschild space-time
    . 2011, 30(7):  19-19. 
    Abstract ( 1083 )   PDF (326KB) ( 406 )  
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    The usual form kinematics equations of a free particle are obtained via directly solving the geodesics equations in the Schwarzschild space time.Comparing with the method in some text books,where the kinematics equations are given by the spherical symmetry of space-time and normalized four-velocity,the results are completely same.However,the geodesics method is more physical,and it is useful and meaningful to understand geodesics equations in a curved space-time.
    Investigation on quasi-phase-matching in second harmonic generation
    . 2011, 30(7):  23-23. 
    Abstract ( 1097 )   PDF (285KB) ( 823 )  
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    We propose a new way to obtain so-called quasi-phase-matching(QPM) condition in the second harmonic generation(SHG) in the real space.The QPM-SHG can be deduced by solving the coupled wave equation.The mismatched angle as a function of x is discussed.We find that a phase shift of 180° can be obtained from the reversion of ferroelectric domain,this restores the phase relation between the interacting waves,thus the SHG conversion efficiency grows continuously.
    The error correction in the measurement of impedance and power factor
    . 2011, 30(7):  26-26. 
    Abstract ( 768 )   PDF (248KB) ( 280 )  
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    The error correction method in the measurement of impedance and power factor is introduced.Both the primary correction method and the accurate correction method are discussed mainly and the modified formula for calculating the impedance and power factor is obtained.An example for measuring the impedance and power factor of the fluorescent lamp circuits is shown.It is seen from the results that there is a large difference between the results of the accurate amendment and the uncorrected case,so a more accurate measurement is required,then the measurement results should be corrected.
    Discussion on experiment of white light interference measured transparent medium refractive index
    . 2011, 30(7):  28-28. 
    Abstract ( 803 )   PDF (457KB) ( 490 )  
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    Double-beam interference phenomenon of white light source is discussed in the case of dispersion medium in optical path.This conclusion can be used to explain the abnormal phenomenon of the experiment of that Michelson interferometer measured transparent medium refractive index,we obtain the results coinciding with the experimental ones and correct the mistake in the correlative reports.
    The discovery of quasicrystal
    . 2011, 30(7):  33-33. 
    Abstract ( 934 )   PDF (430KB) ( 995 )  
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    Quasicrytals discovered during 1980s are new materials.They have lots of potential applications.The experimental discovery led to exploration of an entirely new area of physics,material science as well as mathematics,and resulted in a revolution in the understanding of solid,especially in the understanding of crystal.The historical process on the discovery of quasicrytal is described,and the impact of the discovery on the study of solid is revealed.Professor Dan Shechtman,a material scientist who made the discovery,is also introduced.
    Exploration of "Thermal" elaborate course construction in local comprehensive university
    . 2011, 30(7):  37-37. 
    Abstract ( 722 )   PDF (470KB) ( 382 )  
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    Elaborate course construction in collage is an important measure to improve the quality of teaching.Elaborate course construction in local comprehensive university should rely on local advantages and outstand local characteristics.Exploration and research of "thermal" elaborate course construction in local comprehensive university are done from talents training target,teaching material construction,teaching staff,teaching methods and means.
    The specific charge distribution on the conductive sphere in the electric field of a charged line
    . 2011, 30(7):  41-41. 
    Abstract ( 826 )   PDF (268KB) ( 293 )  
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    This paper investigates the charge distribution on the charged conductive sphere in the electric field of a charged line.The special charge densities in two kinds of situations are calculated.
    Experimental design of measuring physical parameters of CD
    . 2011, 30(7):  44-44. 
    Abstract ( 667 )   PDF (311KB) ( 635 )  
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    A comprehensive experiment is developed for measuring physical parameters of CD.The experiment is rich,interesting and advanced.It has a greater role in promoting the experimental interest and creative ability for students.Meanwhile,the designed experiment is very suitable for physics experiment teaching.
    Points of zero electric potential between two point charges and their field strength generated in a vacuum
    . 2011, 30(7):  47-47. 
    Abstract ( 748 )   PDF (309KB) ( 264 )  
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    For a system with two point charges,the trajectory when the electric potential equal to zero is deduced in the whole space.Also,we discuss the values and directions of field strength under rectangular coordinate systems in the spots of zero electric potential.Numerical simulation with MATLAB is presented to verify the theoretical conclusion.The general approach for solving the problem of electric potential and field strength is summarized.
    A simulation platform for amplitude modulation atomic force microscope
    . 2011, 30(7):  51-51. 
    Abstract ( 925 )   PDF (502KB) ( 795 )  
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    The model of amplitude modulation atomic force microscope(AM-AFM) probe dynamic process is obtained by the Euler-Bernoulli equation.Based on AM-AFM's negative feedback control system with a PID controller,a simulation platform for AM-AFM is established.The simulation results show that the platform can accurately reflect the dynamic characteristic when the probe approaches and scans the sample.In consequence,for students doing the AM-AFM experiment,the platform can be used as an effective tool,which helps the students to have a deeper understanding on the AM-AFM,as well as a tentative experience before practice.