The thermal expansion of the crystal lattices of germanium, silicon, and the alloys InSb and GaAs has been measured by the hightemperature X-ray diffraction method. The coefficients in the expansion equation αt=α0(1+αt+βt2+γt3+δt4)for the materials investigated were found to be as follows: Germanium (99.9999% purity, in the temperature range 0-900℃): α=5.019×10-6, β=1.230×10-9, γ=5.420×10-12, δ=-4.000×10-15 and α0, the lattice parameter at 0℃, is 5.64573 kX. Silicon (99.9999% purity, 0-900℃): α=3.893×10-6, β=-2.101×10-9, γ=5.125×10-12, δ=-1.833×10-15 and α0=5.41921 kX. InSb (zone-refined, 0-500℃):α=5.724×10-6, β=-0.036×10-9, γ=-0.050×10-12, δ=0.166×10-15 and α0=6.46420 kX. GaAs(zone-refined, 0-750℃): α=6.174×10-6, β=0.140×10-9, γ=-1.425×10-12, δ=2.282×10-15 and α0=5.64037 kX. The lattice parameters at various temperatures calculated with these constants are in excellent agreement with the observed values.
The thermal expansion of the crystal lattices of germanium, silicon, and the alloys InSb and GaAs has been measured by the hightemperature X-ray diffraction method. The coefficients in the expansion equation αt=α0(1+αt+βt2+γt3+δt4)for the materials investigated were found to be as follows: Germanium (99.9999% purity, in the temperature range 0-900℃): α=5.019×10-6, β=1.230×10-9, γ=5.420×10-12, δ=-4.000×10-15 and α0, the lattice parameter at 0℃, is 5.64573 kX. Silicon (99.9999% purity, 0-900℃): α=3.893×10-6, β=-2.101×10-9, γ=5.125×10-12, δ=-1.833×10-15 and α0=5.41921 kX. InSb (zone-refined, 0-500℃):α=5.724×10-6, β=-0.036×10-9, γ=-0.050×10-12, δ=0.166×10-15 and α0=6.46420 kX. GaAs(zone-refined, 0-750℃): α=6.174×10-6, β=0.140×10-9, γ=-1.425×10-12, δ=2.282×10-15 and α0=5.64037 kX. The lattice parameters at various temperatures calculated with these constants are in excellent agreement with the observed values.
The capability of redundancy method for increasing the reliability of circuit elements of both switch- and nonswitch-type is investigated in this paper. The reliability gain of various ways of circuit connections is derived with regard to open circuit and short circuit failures. The change of loading effects of all redundant elements due to the failure of a few elements among them is also considered. The evaluation of the average life of a redundancy elements shows that the redundancy technique is particularly suitable for short period operation or nonreparable systems. Some design considerations for practical applications are discussed in substantial detial with illustrations.
The capability of redundancy method for increasing the reliability of circuit elements of both switch- and nonswitch-type is investigated in this paper. The reliability gain of various ways of circuit connections is derived with regard to open circuit and short circuit failures. The change of loading effects of all redundant elements due to the failure of a few elements among them is also considered. The evaluation of the average life of a redundancy elements shows that the redundancy technique is particularly suitable for short period operation or nonreparable systems. Some design considerations for practical applications are discussed in substantial detial with illustrations.
In this article, the elastic model of lattice vacancy is critically analysed, and a general expression for the interaction energy of vacancy with an arbitrary internal stress system is given. As an example of physical interest, the formula for the elastic interaction energy of prismatic dislocation loop and vacancy is derived, and numerical results on dislocation loop in Al are presented and discussed.
In this article, the elastic model of lattice vacancy is critically analysed, and a general expression for the interaction energy of vacancy with an arbitrary internal stress system is given. As an example of physical interest, the formula for the elastic interaction energy of prismatic dislocation loop and vacancy is derived, and numerical results on dislocation loop in Al are presented and discussed.
The α0 excitation curve of Na23(p,α) reaction has been measured at proton energies in the neighbourhood of 1416 Kev. While only one resonance level was known previously in this region, we have discovered the presence of two levels, one at 1416.8 Kev (this level was known at 1415.1 Kev according to Andersen's determination of Na23(p,γ) levels, but with Ep =992.0 Kev for Al27(p, γ) reaction as standard ofenergy calibration, we have 1415.1×992.0/990.8=1416.8, and another at 1410.4 ± 1.0 Kev.The decay of this latter level is mainly through emission of a particle to the ground level of Ne20.
The α0 excitation curve of Na23(p,α) reaction has been measured at proton energies in the neighbourhood of 1416 Kev. While only one resonance level was known previously in this region, we have discovered the presence of two levels, one at 1416.8 Kev (this level was known at 1415.1 Kev according to Andersen's determination of Na23(p,γ) levels, but with Ep =992.0 Kev for Al27(p, γ) reaction as standard ofenergy calibration, we have 1415.1×992.0/990.8=1416.8, and another at 1410.4 ± 1.0 Kev.The decay of this latter level is mainly through emission of a particle to the ground level of Ne20.
A graphical analysis is developed for the solution of transient response in nonlinear systems. The nonlinear system is first represented by its equivalent circuits with linear and nonlinear R, L, C circiut elements. By applying Kirchhoff's rules of circuit analysis with properly chosen variables, a set of nonlinear differential equations of the desired form is obtained. To solve the equations, integrations are performed on the phase plane with the graphical method proposed in the paper. This method of analysis possesses the following advantages: (1) The nonlinear functions can be obtained directly from exprimentally determined curves. Analytical expressions are not re quired. (2) The calculation is relatively easy and only simple tools are used. (3) Satisfactory accuracy is obtainable. This method of analysis is applied, in particular, to calculate the transient response of basic circuits of tunnel-diodes. Results are in good agreement with the experiments and with those obtained by electronic computer.
A graphical analysis is developed for the solution of transient response in nonlinear systems. The nonlinear system is first represented by its equivalent circuits with linear and nonlinear R, L, C circiut elements. By applying Kirchhoff's rules of circuit analysis with properly chosen variables, a set of nonlinear differential equations of the desired form is obtained. To solve the equations, integrations are performed on the phase plane with the graphical method proposed in the paper. This method of analysis possesses the following advantages: (1) The nonlinear functions can be obtained directly from exprimentally determined curves. Analytical expressions are not re quired. (2) The calculation is relatively easy and only simple tools are used. (3) Satisfactory accuracy is obtainable. This method of analysis is applied, in particular, to calculate the transient response of basic circuits of tunnel-diodes. Results are in good agreement with the experiments and with those obtained by electronic computer.
The radiation behaviour of the molecules in a detuned cavity has been treated with a more rigorous method of quantum mechanics. The experimental finding of Higa, that when the deutuning of the first cavity reaches a critical value, the second cavity suddenly breaks out into oscillations at the centre frequency of the molecules, is interpreted. A formula is obtained for the critical detuning which leads to the sudden oscillation. The experimental curves obtained by Страховский and Татренков about the dependence of the radiation power of the molecules in the second cavity on the frequency detuning is qualitatively interpreted.
The radiation behaviour of the molecules in a detuned cavity has been treated with a more rigorous method of quantum mechanics. The experimental finding of Higa, that when the deutuning of the first cavity reaches a critical value, the second cavity suddenly breaks out into oscillations at the centre frequency of the molecules, is interpreted. A formula is obtained for the critical detuning which leads to the sudden oscillation. The experimental curves obtained by Страховский and Татренков about the dependence of the radiation power of the molecules in the second cavity on the frequency detuning is qualitatively interpreted.
The stability of intense electron beam via the periodic static electric and magnetic fields is discussed. The stability and instability regions of cylindrical electron beam through periodic harmonic electromagnetic field and periodic anharmonic fields in sawtooth, square, and trapezoid forms are given. Compared with the major instability regions of the various fields, the instability region of the saw-tooth form is smaller than others.When space charge effect is appreciable, the electron beam in the stable region is conditionally rather than unconditionally stable. It is dependent on the intensity of the space-charge current and the amplitude of the eletron beam.
The stability of intense electron beam via the periodic static electric and magnetic fields is discussed. The stability and instability regions of cylindrical electron beam through periodic harmonic electromagnetic field and periodic anharmonic fields in sawtooth, square, and trapezoid forms are given. Compared with the major instability regions of the various fields, the instability region of the saw-tooth form is smaller than others.When space charge effect is appreciable, the electron beam in the stable region is conditionally rather than unconditionally stable. It is dependent on the intensity of the space-charge current and the amplitude of the eletron beam.
The broadening of the M?ssbauer line due to the fluctuation of lattice vibration (named thermal broadening) is discussed. The quantitative formula relating this broadening to the structure of localized vibrational modes (with discrete frequencies) round the impurity radiating atom in crystal is obtained, and the thermal broadening in the degenerate case is analysed in some detail.
The broadening of the M?ssbauer line due to the fluctuation of lattice vibration (named thermal broadening) is discussed. The quantitative formula relating this broadening to the structure of localized vibrational modes (with discrete frequencies) round the impurity radiating atom in crystal is obtained, and the thermal broadening in the degenerate case is analysed in some detail.
An expression for the compressibility ▽·ξ of a plasma is obtained from the linearized magnetohydrodynamic equations of motion. This compressibility term, in general, consists of two different parts: the first connects with the longitudinal initial motion of the plasma, and the second with the uniform motion (dilatation and contraction) of the plasma-carrying magnetic tubes. For a plasma column, several cases are considered which permit us to simplify to some extent the solution of the equation of motion including the compressibility term. With the aid of these results, a dispersion relation describing the motion of the plasma column with uniform current distribution is derived and analysed.
An expression for the compressibility ▽·ξ of a plasma is obtained from the linearized magnetohydrodynamic equations of motion. This compressibility term, in general, consists of two different parts: the first connects with the longitudinal initial motion of the plasma, and the second with the uniform motion (dilatation and contraction) of the plasma-carrying magnetic tubes. For a plasma column, several cases are considered which permit us to simplify to some extent the solution of the equation of motion including the compressibility term. With the aid of these results, a dispersion relation describing the motion of the plasma column with uniform current distribution is derived and analysed.
A study has been made on the effects of hydrostatic pressure at room temperature on peak currents Ip, valley currents lv, peak voltages Vp, valley voltages Vv and the exponential excess currents Ix of several narrow GaAs P-N junctions. The pressure ranges from the atmospheric pressure up to 18000 Kg/cm2.The exponential decrease of the peak voltage Vp and the slope S of the exponen-tial excess current (S=(dlnIx)/dV) with the increase of pressure can be explained in termsof the pressure variations of the effective mass of GaAs. It is suggested therefore that pressure dependences of both the energy gap and the effective mass should be taken into account in analyzing the pressure dependent tunneling data of the highly degenerate GaAs P-N junctions. A brief discussion has also been made on the other experimental results.
A study has been made on the effects of hydrostatic pressure at room temperature on peak currents Ip, valley currents lv, peak voltages Vp, valley voltages Vv and the exponential excess currents Ix of several narrow GaAs P-N junctions. The pressure ranges from the atmospheric pressure up to 18000 Kg/cm2.The exponential decrease of the peak voltage Vp and the slope S of the exponen-tial excess current (S=(dlnIx)/dV) with the increase of pressure can be explained in termsof the pressure variations of the effective mass of GaAs. It is suggested therefore that pressure dependences of both the energy gap and the effective mass should be taken into account in analyzing the pressure dependent tunneling data of the highly degenerate GaAs P-N junctions. A brief discussion has also been made on the other experimental results.