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Table of Content
20 February 2012 Volume 31 Issue 2
著者文摘
New comprehension of the Taylor series expansion ②——Addition formulas and multiplications formulas of special functions
. 2012, 31(2): 1-1.
Abstract
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1186
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(407KB) (
595
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As a new comprehension of the Taylor series expansion, the addition formulas and multiplication formulas are deduced from the Taylor series expansion. About 50 formulas are obtained for the common special functions. Most of them can not be found in the main literatures.
The minimum work for picking out an arbitrary shape object from liquid in a container
. 2012, 31(2): 6-6.
Abstract
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719
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(249KB) (
368
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This article use law of mechanicl energy to bring forward the formula for calculating the minimum work for picking out an arbitrary shape object from liquid in a container.
The strict theory on the rate of change over time of the volume integral that divergence of vector field to a sports region of space
. 2012, 31(2): 8-8.
Abstract
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821
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(418KB) (
407
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Under the circumstances of sport space area being full of medium and sport space area being full of medium and vacuum, we propose two computing methods about the rate of change over time of volume integral that divergence of vector field to a sports region of space. If a special viewpiont look upon the change of integraition space area is used, the two kinds of circumstances could be computed by the use of a unified way. Under the circumstances of sports space region being full of medium and vacuum, if the velocity v is keeped to be the same as the one on the boundary face S of the integration V conform to the truth, but give V a new veloctiy field v（r,t） which rate of change with the space is continuous or block continuous, the computing method of locking volume ele- ment is still applicable.
Scattering particle interactions to He（ e, 3e） fivefold differential cross-section contribution
. 2012, 31(2): 13-13.
Abstract
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606
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(332KB) (
306
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The He（e,3e） fivefold differential cross-section under the equal-energy share of knocked electron geometry arrangement is calculated, in which the incident energies are 5599 eV and 1099 eV, respectively. The contributions of different interactions as well as their interference effect in the He（e, 3e） process make to fivefold differential cross-section are compared. The result indicates that the theoretical calculation is in agreement with the experimental data in the error range, and each kind of interaction as well as the interference effect to fivefold differential cross-section＇ s influence should be not neglected.
Exact solution of arctangent fractional transformation of motion differential equation of single pendulum without damping
. 2012, 31(2): 16-16.
Abstract
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1142
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(233KB) (
402
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The differential equation of motion of single pendulum without damping is a kind of nonlinear ordinary differential equation with the physical background and the study of exact solutions in nonlinear science is an important work. In order to lay the foundation for studying nonlinear behavior of these issues, four kinds of exact solutions are obtained by using the arctangent fractional transformation method of sine function and introducing Riccati auxiliary equation based on the F-expansion method. The arctangent fractional transformation method applied in such equation is a universal conclusion.
A method to calculate the magnetic field of circular current
. 2012, 31(2): 19-19.
Abstract
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936
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690
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The magnetic field of a circular current loop is calculated by using an integral transformation.
The analytical solution of bound states the level of alkali metal atoms and hydrogen-like ions
. 2012, 31(2): 21-21.
Abstract
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777
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(310KB) (
520
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The atomic core model of alkali metal and hydrogen-like atoms is analyzd from physical essence images, polarization and throughout the role of quantitative analysis and experimental data. The semi-experiential internal interaction potential of alkali metal and hydrogen-like atoms is introduced and the stationary Schrodinger equations is established. With perturbation theory obtaining level, the effective main quantum number and effective nuclear change number and its losses are derived further.
Electromagnetic energy loss in medium and its application
. 2012, 31(2): 25-25.
Abstract
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1030
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(333KB) (
952
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The power density of electromagnetic energy loss is deduced from the Maxwell＇s equations, which is dominated by the factors as the imaginary component of relative dielectric constant, of magnetic permeability, external field frequency and the square of field strength. Based on the electromagnetic energy loss, we analyze the principles of microwave heating, and present the thermal energy balance equation in microwave field. This work contributes to improve the understanding of interactions between the electromagnetic field and material, and has some directive meanings to the relative theory research and technological applications.
Revising sampling theorem and experimental research method of cycle phenomenon
. 2012, 31(2): 28-28.
Abstract
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794
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PDF
(481KB) (
337
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The sampling theorem in signal and system theory,demands sample the time zone limitlessly widely, amount of data sampled is many limitlessly. This is a kind of idealized situation. It can only be limited to sample the width of time zone and amount of data sampled actually. Therefore, it is difficult for the sampling theorem to use and explore the law that the physical quantity evolved with time. The need of combining the physics experiment and studying, we propose the revising sampling theorem for utilizing limited sampled data and revising sampling theorem, which can catch the evolution law of cycle physical quantity accurately. The method is, fetch the time in- terval T8 as small as possible, fetch the number of times of observation as large as possible, to observe cycle physi- cal quantity N times. We analyze the sampled data and find out cycle T of the physical quantity, adjust T and N by observing repeatedly,make NT8/T equal to the integer. We calculate spectral Xs（f） which samples the data, utilize the revising sampling theorem and X （f）, and get spectral X （f） of cycle physical quantity fast. According to X（f） , we rebuild law that the cycle physical quantity evolved with time. As an example, large tilt angle simple pendulum as the research object, we show the method and process of cycle phenomenon law.
Instrument for measuring temperature characteristic of high power LED
. 2012, 31(2): 33-33.
Abstract
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647
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(362KB) (
542
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An instrument for measuring the temperature characteristic of a high power LED is developed by using a semiconductor heating/cooling element to make the LED＇s temperature rise or fall, in which a pt100 surface mounted resistor is used as a temperature sensor, and a light sensor with spectral response that emulates the human eye is used as a luminous intensity detector. The temperature characteristics of the photoelectric parameters, such as luminous intensity, luminous efficiency, of the 1 watt white LED supplied by a constant current source or a constant voltage source are investigated, respectively. The experimental results show that this instrument has advantages of fast temperature measurement, high accuracy, low cost and simple operation.
Giant magneto resistance effect and its application in physics experiment
. 2012, 31(2): 37-37.
Abstract
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696
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PDF
(530KB) (
805
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The function of magneto resistance sensor effect is briefly introduced. Relationships between GMR and magnetic field as well as output coming from AA002 series analog sensors and magnetic field are measured by using the AA002 series analog sensors. Based on the experimental results, its characteristics are analyzed. A series of physics experiments using giant magneto resistance sensor is designed.
The spectroscopic experiment of diatomic molecule using a grating spectrometer to measure N2
. 2012, 31(2): 42-42.
Abstract
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1073
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PDF
(290KB) (
925
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A new scheme is proposed for the spectroscopic experiment of diatomic molecule based on nitrogen molecules （N2） in the college course of modern physics experiment. The emission spectrum of the second positive band of N2 can be recorded with a normal grating spectrometer equipped with a photomuhiplier as detector and a glow discharge of low-pressure N2 as the spectral source. According to the basic theory of electronic-vibrational spectrum of diatomic molecule, the harmonic frequencies and anharmonic parameters in the upper and lower electronic states of N2 can be derived from the observed spectrum.
Physics talent training mode in Harvard University
. 2012, 31(2): 45-45.
Abstract
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718
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PDF
(654KB) (
536
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The physics talent training mode in Harvard University is discussed, such as selection method with both flexible and rigorous, education schemes with both depth and width, evaluation system with both loose and and construction of organization with both competition and cooperation.
Development of ethanol gasoline concentration measuring instrument based on ultrasound phase difference method
. 2012, 31(2): 51-51.
Abstract
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818
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PDF
(368KB) (
543
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A new way of ethanol gasoline concentration determination is proposed based on the ultrasound phase difference method. The on-line concentration measuring instrument is also designed by the method. When the temperature is 290K and ethanol gasoline volume concentration is at between 3% and 24% , we use the instrument to establish relationship between ethanol gasoline concentration and phase. The experimental results show that the ultrasound concentration measuring instrument can not only measure ethanol volume concentration in ethanol gasoline solution accurately and real-time, hut also come up a new way for measuring vehicle ethanol gasoline and other binary solution accurately.
Giant magneto resistance effect and its application in physics experiment
. 2012, 31(2): 55-55.
Abstract
(
781
)
PDF
(351KB) (
479
)
Related Articles
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Metrics
The function of magneto resistance sensor effect is briefly introduced. Relationships between GMR and magnetic field as well as output coming from AA002 series analog sensors and magnetic field are measured by using the AA002 series analog sensors. Based on the experimental results, its characteristics are analyzed. A series of physics experiments using giant magneto resistance sensor is designed.
One-dimensional barrier penetration
. 2012, 31(2): 59-59.
Abstract
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1308
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PDF
(245KB) (
1061
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Quantum tunneling is a very important quantum phenomenon in quantum mechanics. The question of one-dimensional barrier penetration is studied in this paper. Three different forms ofthe results, namely,differences of the energy of the particle, E〉Vo, E〈Vo and E= V0, can be unified by employing ＂effective barrier＂. Some physical phenomena about one-dimensional barrier penetration are discussed in the extreme conditions.
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