共查询到20条相似文献,搜索用时 625 毫秒
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R. A. Vadov 《Acoustical Physics》2005,51(3):265-270
The disagreement between the experimental and calculated positions of the first convergence zone are known from many publications. The most probable cause for such a disagreement, namely, the incorrect specification of the input data for the calculations, is considered. The lack of simultaneity between the hydrological surveys of the region and the acoustic experiments is emphasized. The experimental data obtained by the author in five ocean regions are presented. These data characterize the diurnal variability of the distance from the source to the nearest boundary of the convergence zone. The relations proposed by different researchers for calculating the sound speed from the temperature, salinity, and hydrostatic pressure are analyzed. It is shown that these relations lead to a substantial difference in the estimated depth dependence of the hydrostatic gradient of the sound speed. The position of the first convergence zone is calculated for the propagation conditions determined by vertical temperature and salinity profiles with the subsequent recalculation of these profiles into sound speed profiles by using eight different formulas known from the literature. It is shown that different formulas lead to different values of the distance to the first zone; this difference is substantially greater than that between the calculations and experiment. The necessity of improving the recalculation relations in view of the experimental data on sound propagation in natural oceanic waveguides, including the data on the actual positions of the convergence zones, is emphasized. 相似文献
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Technical Physics - The object of this work is the apokamp—a new type of plasma jet, which is formed from a bright offshoot emerging at the bending point of a channel of a high-voltage... 相似文献
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J. Šlechta 《Czechoslovak Journal of Physics》1968,18(10):1299-1308
On the basis of the classical theory of radiation produced in incomplete Coulomb interaction, a formula is derived for the coefficient of the bremsstrahlung of fully ionized plasma. In the region of rectilinear approximation a comparison is made with the results of the quantum formula derived from the Born approximation. Furthermore, the influence of dispersion upon the emission coefficient is taken into account; some relations for the region of dispersion are given. 相似文献
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L. E. Zhmur 《Radiophysics and Quantum Electronics》1972,15(4):367-371
One-dimensional nonisothermal diffusion in ionospheric plasma (the F-region) is considered in the stationary case. The analysis is carried out for two species of positive ions with allowance for the ionization and recombination processes and the effect of gravity. A system of two coupled equations is derived for the concentrations of the electrons and ions. A transition is made to the case when the ions which determine dissociative recombination are impurity ions. For this case criteria are presented whose fulfilment causes the distribution that has been found to coincide with that obtained by Mange [9] without allowance for photochemical processes. 相似文献
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We propose a procedure for renormalizing the Casimir energy that makes the steps that are used in the standard renormalization procedure, that is, regularization, subtraction, and deregularization, implicit. The proposed procedure is based on the calculation of a set of convergent sums, each of which is related to the initial divergent sum of the non-renormalized Casimir energy. Next, we construct a system of linear equations that relates this set of convergent sums to the renormalized Casimir energy. The unknown renormalized Casimir energy is obtained as a result of solving this system of equations. In this case, both the calculations of the convergent sums and the subsequent solution of the system of linear equations are performed with a certain (generally speaking, arbitrary) ordered accuracy; thus, the result is also approximate. The proposed procedure is, first, more computationally effective than the standard one, and, second, applicable not only to the problems where a transcendental equation for the spectrum can be written, but also to the problems where the spectrum is known only numerically. 相似文献
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A method of calculation is presented for the yield of an electron excitation process by a channelled particle in a single encounter with an atomic row or plane in a crystal. It is shown that, if ψ is the initial angle between the ion trajectory and the row or plane, the number of inner-shell electrons excited is an increasing function of ψ whereas the number of outer electrons excited may decrease with increasing ψ. 相似文献
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Design and analysis of the tunnel connecting the beamcorridor and the spectrum hall of the CSNS 总被引:1,自引:0,他引:1
There is a tunnel connecting the beamcorridor and the target station in the spectrum hall in the CSNS project. The length of the tunnel is about 20 m. The shielding design of the tunnel is very significant for the persons working in the spectrum hall because the tunnel is not covered by soil for shielding. In order to reduce the dose rate at the exit of the cable ducts, we use the ISIS construction, which is designed with four turnings, as a reference for the tunnel design. The thickness of the shielding is obtained by a simulation with the Monte Carlo Code FLUKA. The result is compared with the data obtained with Moyer Mode and the reliability of the simulation is proved. This paper provides the basis for the design of the tunnel. 相似文献
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M. M. El-Nicklawy A. F. Hassan S. M. M. Salman A. Abdel-Aty 《Optics & Laser Technology》2005,37(5):363-368
The bistability behavior of a nonlinear absorbing medium inside a Fabry–Perot resonator driven by an external quasi-monochromatic field is studied. The driving field is considered to be of a Gaussian and Lorentzian spectral line profile. The effect of the spectral half-width on the bistability is discussed. The mathematical treatment is carried out through an interferometric point of view. The dependence of the driving intensity required to initiate bistability on the standing wave established inside the resonator is represented. 相似文献
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Design and analysis of the tunnel connecting the beamcorridor and the spectrum hall of the CSNS 下载免费PDF全文
There is a tunnel connecting the beamcorridor and the target station in the spectrum hall in the CSNS project.The length of the tunnel is about 20 m.The shielding design of the tunnel is very significant for the persons working in the spectrum hall because the tunnel is not covered ed soil for shielding.In order to reduce the dose rate at the exit of the cable ducts,we use the ISIS construction,which is designed with four turnings,as a reference for the tunnel design.The thickness of the shielding is obtained by a simulationwith the Monte Carlo Code FLUKA.The result is compared with the data obtained with Moyer Mode and the reliability of the simulation is proved.This paper provides the basis for the design of the tunnel. 相似文献
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光电探测器对光谱仪器精度的影响 总被引:3,自引:0,他引:3
通过优化光谱探测环节来提高光谱仪器的精度是改进或研制新型光谱仪的重要途径。为此,文章基于对光电成像系统中光学传递函数的研究,建立了光谱图像经探测器积分抽样后重建的数学模型,并在此基础上分析了光电探测器积分抽样特性参数对光谱线频谱的影响,讨论了光谱线半宽度与探测器积分区间宽度、灵敏度及抽样间隔的关系,提出了准确重建光谱线,提高光谱仪器波长精度和光度精度的探测器优化原则。 相似文献
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实际的海洋环境是非常复杂的,存在着海洋自噪声、舰船噪声、生物发声等,阵元接收到的噪声信号存在一定的相关性,此时基于传统阵列信号处理的目标方位估计方法的性能将变差,针对这一问题,提出了一种实部消除方法.首先从阵元接收环境噪声的物理机理出发,将圆环阵接收的噪声场分解为对称噪声场和非对称噪声场,并且研究发现对称噪声场只影响数据协方差矩阵的实部.然后通过消除协方差矩阵实部,达到消除对称噪声场的目的,提高信噪比,但是同时产生了虚假声源.针对虚假声源的问题,提出了基于优化算法重构协方差矩阵实部的方法,消除了虚假声源的影响.仿真分析与海试数据处理结果表明:该方法明显消除了对称噪声,提高了信噪比,改善了阵列信号处理算法的性能.实部消除方法易于实现,有一定的工程应用价值. 相似文献
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James M. Kingsley 《Foundations of Physics》1975,5(2):295-300
The special theory of relativity is based on two postulates: (I) All inertial frames are equivalent for the performance of physical experiments; and (II) the velocity of light is a universal constant. It is shown that if postulate I is true, then postulate II is not true, and if postulate II is true, then postulate I is not true. Further, it is shown that the only possible velocity consistent with postulate I follows the rule that the velocity of light with respect to the observer is equal to the velocity of light with respect to the source plus the velocity of the source with respect to the observer. 相似文献
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A. N. Izotov V. V. Kveder Yu. A. Osip’yan É. A. Steinman R. K. Nikolaev N. S. Sidorov 《Journal of Experimental and Theoretical Physics》1998,87(6):1205-1213
The absorption coefficient of perfect single crystals of the fullerene C60 is measured in the energy range 1.6–2.1 eV at temperatures from 4.2 to 300 K. An absorption fine structure is discovered
in the and is assigned to electronic and vibronic transitions with the production of free excitons and excitons localized
on structural defects. It is shown that in the region of the structural phase transition from a face-centered cubic structure
to a simple cubic structure the absorption coefficient undergoes a jump, which is associated with an energy shift of the free
exciton line toward lower energies. It is discovered that spatial inhomogeneity, which is associated with the growth of the
new phase from a finite number of nuclei, appears in the crystal at the time of this transition.
Zh. éksp. Teor. Fiz. 114, 2211–2224 (December 1998) 相似文献
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R. Brout 《Foundations of Physics》1987,17(6):603-619
Time arises in the theory of gravity through the semiclassical approximation of the gravitational part of the solution of the Wheeler-De Witt equation in the manner shown by Banks (SCAG). We generalize Banks' procedure by grafting a Born-Oppenheimer type approximation onto SCAG. This allows for the feedback of matter onto gravity, wherein the latter is driven by the (quantum) mean energy-momentum tensor of matter. The wave function is nonvanishing in classically forbidden configurations of gravity. In SCAG this is described by the evolution of matter in imaginary time. This is interpreted as an inverse temperature, and the norm of the matter wave function, no longer conserved for these gravitational configurations, is a partition function. A simple cosmological model is worked out to illustrate these ideas. In this model it is shown that the temperature of the matter which emerges into the classically permitted region is the inverse bounce time of the bounce executed by the system in the forbidden region (behind the horizon).Time present and time past are both perhaps present in time future. And time future contained in time past. If all time is eternally present All time is unredeemable.—T. S. Eliot, Burnt Norton,Four Quartets, 1943.In honor of Ilya Prigogine on the occasion of his 70th birthday. 相似文献
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We propose one a variant of calculation of the energy spectrum of bound state systems with relativistic corrections. In the
framework of quantum field theory, an expression that takes into account relativistic corrections to the mass of the bound
state with a known nonrelativistic pair interaction potential is proposed on the basis of calculating the asymptotic behavior
of correlation functions of the corresponding field currents with the necessary quantum numbers. Excluding the time variables
allows one to determine nonperturbative corrections to the interaction potential. The following results have been obtained
in the framework of this approach. The nonperturbative corrections arising due to the relativistic nature of a system to the
interaction Hamiltonian are determined. The dependence of the constituent mass of bound-state forming particles on the free
state mass and on the orbital and radial quantum numbers is analytically derived. The energy level shift of muonic hydrogen
taking into account relativistic corrections is calculated. The energy spectrum of a wide class of potentials that describe
the Coulomb bound state is analytically derived with relativistic corrections. The mass spectrum of the glueballs and the
constituent masses of the gluons are analytically calculated taking into account spin-orbit, spin—spin, and tensor interactions.
Our numerical results have shown very good agreement with the lattice data. Taking into account nonperturbative and nonlocality
characters of interactions, the mass spectrum of the mesons consisting of light-light and light-heavy quarks with orbital
and radial excitations is determined. Our results show that good agreement with the experimental data for the slope and the
intercept of the Regge trajectory can be obtained only taking into account the nonperturbative and the nonlocal characters
of interactions. The dependences of the constituent masses of constituent particles on the masses of a free state are certain.
When quarks are light, then the difference between current and valent masses of quarks is greater than valent masses of quarks,
and when quarks are heavy, then the difference between these masses is insignificant. One of the alternative variants of taking
nonlocality into account has been suggested for the definition of properties of hadrons at large distances. The dependence
of the constituent masses of constituent particles on the radius of confinement is determined. 相似文献