共查询到20条相似文献,搜索用时 15 毫秒
1.
Power of an electromagnetic field in a plane is derived exactly as a function of the angular spectrum of only electric field components at another plane based on Maxwell equations and Poynting vector. Then, this quantity is acquired as a function of the electric field components. In this calculation, a function appears that is general and does not depend on the electromagnetic field function. 相似文献
2.
A power analysis of the lossy negative refractive index or left-handed slab lens is described. The presence of vortices in the image plane is revealed with small loss or gain, and these are attributed to the influence of field growth in the evanescent spectrum. 相似文献
3.
以装备电磁兼容性量化需求出发,根据电磁兼容试验数据的特点,将试验结果分为EMI类和EMS两种类型进行分析,提出了EMI和EMS两类试验结果量化表征方法并构建了数学模型。针对EMI类试验数据特点,通过超标数据占比和超标特征两个维度完成了EMI数据的量化表征模型构建;针对EMS类试验结果仅为定性描述这一特点,结合试验过程中的敏感现象,从干扰源及敏感频段两个维度进行量化表征模型构建,通过软件实现了相关量化模型,并通过试验结果量化算例予以验证。以试验结果开展的量化表征研究工作,获得了试验项目的数学量化模型,实现了基于国军标试验标准的电磁兼容试验结果量化表征。 相似文献
4.
5.
M. V. Davidovich 《Technical Physics》2010,55(5):630-635
The simplest dispersion relation determined by dissipation due to conduction is considered; the electromagnetic energy density
in a plane monochromatic wave and its (phase and group) velocity are determined, as well as the energy and momentum transfer
rates. It is shown that the energy density at low frequencies in this case has the form of the electrostatic density, in which
the permittivity is replaced by its real part, and the energy transfer rate in a plane electromagnetic wave is equal to the
phase velocity. The group velocity may exceed the speed of light. 相似文献
6.
This paper is devoted to study the effects of electromagnetic field on the energy density inhomogeneity in the relativistic self-gravitating fluids for spherically symmetric spacetime. Two important equations of the Weyl tensor are formulated which help to analyze the energy density inhomogeneity in this scenario. We investigate two types of fluids, i.e., non-dissipative and dissipative. The non-dissipative fluid further includes dust, locally isotropic, and locally anisotropic charged fluids. We explore the effects of different factors on energy density inhomogeneity in all these cases, in particular, the effect of charge. 相似文献
7.
《Physics letters. A》1987,121(1):19-24
The structure of the energy density of the virtual electromagnetic field surrounding a ground-state hydrogen atom is discussed in the framework of nonrelativistic QED. Both the electric and the magnetic part of this energy density are analysed in terms of a shell structure, similar to that previously proposed for the coarse grained energy density W(r). The physical meaning of this shell structure is discussed. It is suggested that, differently from W(r), the energy density investigated here can be measured experimentally, and it is shown that it is rich of detailed information about the dynamical structure of the source atom. 相似文献
8.
9.
Dongliang Gao Andrey Novitsky Tianhang Zhang Fook Chiong Cheong Lei Gao Chwee Teck Lim Boris Luk'yanchuk Cheng‐Wei Qiu 《Laser \u0026amp; Photonics Reviews》2015,9(1):75-82
This paper investigates the singular optics of nonparaxial light beams in the near field when the light behaves as a tractor beam. New insights into the optical pulling force, which is usually represented by integrating the stress tensor at a black box enclosing the object, are interpreted by the optical singularity of the Poynting vector. The negative nonconservative pulling force originates from the transfer of the azimuthal Poynting vector to the longitudinal component partly owing to the presence of a scatterer. The separatrice pattern and singularity shifts of the Poynting vector unanimously exhibit a differentiable near‐field distribution in the presence of optical pulling force. A new method is established to calculate the near‐field optical force using the differential Poynting vector in the far field. The results obtained provide a clear physical interpretation of the light–matter interaction and manifest the significance of singular optics in manipulating objects.
10.
A. Salam 《Molecular physics》2013,111(8):797-800
The van der Waals dispersion interaction between a molecule that is electrically polarizable and one that is magnetically susceptible, is recalculated within the framework of non-relativistic quantum electrodynamics. The energy shift is obtained in a simple way by calculating the response of a test polarizable body to the electromagnetic energy density due to a second source molecule. It is confirmed that the near-zone asymptote of the potential between an electric dipole polarizable molecule and a paramagnetic one varies as R ? 4. Inclusion of the often neglected diamagnetic coupling term, however, results in an R ?5 dependent short-range behaviour, which is seen to dominate over the paramagnetic contribution in the near-zone. For larger intermolecular distances, the expected R ?7 dependence on separation is found for both paramagnetic and diamagnetic susceptible molecules interacting with an electric dipole polarizable one. 相似文献
11.
Deparis O 《Optics letters》2011,36(20):3960-3962
In spite of the fact that solutions to Maxwell's equations in stratified isotropic optical media are well known, it appears that an explicit expression of the Poynting vector flux spatial evolution inside such a medium has not been derived so far. Based on exact electromagnetic field solutions in the transfer-matrix formalism, I derive such an expression and show that, due to the presence of counterpropagating waves in the medium, an additional contribution to the flux appears that exists only in optically absorbing layers and arises from the interference between these waves. Based on this theory, the concept of incremental absorption is introduced for the calculation of the light absorption profile along the stratification direction. As an illustration of this concept, absorption profiles in a Si-based thin-film tandem solar cell are predicted at typical wavelengths. 相似文献
12.
13.
Conclusions When the parameter is relatively large (case b), thus allowing an oscillating type of distribution of the field amplitude on the aperture , the deep field minimum at point Q is attained by interference of creeping waves of large amplitude.For small values the excitation intensity of higher creeping-wave modes drops off (as a result of reduction of the field amplitude on the boundaries of ) and minimization of the field at Q involves reduction of the amplitude of the first creeping wave, as well as interference, which leads to less deep compensation in this case.We should note that in antennas of large dimension (ka>50), interference of creeping waves manifests itself only in the penumbral region.When the requirements on the stability of the field minimum are stringent, it is necessary to introduce additional conditions into the optimization problem, e.g., to carry out a search for the minimum in the region.In concluding, the authors wish to thank I. M. Polishchuk and V. S. Cherenkov for useful discussions.Odessa Electrotechnical Institute of Communications. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 23, No. 10, pp. 1250–1255, October, 1980. 相似文献
14.
《Comptes Rendus Physique》2009,10(1):4-12
This article deals with the electromagnetic environment management problem within the context of high speed digital transmissions deployed in wired telecommunication networks.Traditionally, Electromagnetic Compatibility (EMC) is assured by filtering for better electromagnetic immunity, and by cable shielding for emission limitation.However, like cognitive radio, we can also, for high speed wired transmissions, treat the EMC as an intelligent and autonomous system capable of perceiving its environment, interpreting it, making suited decisions, and reacting according to the constraints related to the electromagnetic environment.In this context, some application examples are here given in order to illustrate this evolution towards a cognitive EMC in wired networks. To cite this article: A. Zeddam et al., C. R. Physique 10 (2009). 相似文献
15.
16.
Computational and experimental methods for determining the effective surface energy density under the dynamic loading conditions are proposed. The results are presented for two grades of steel and titanium alloy VT-6S in the submicrosecond range of the loading pulse duration. The resultant values of the effective surface energy density are compared with the results obtained by other authors. 相似文献
17.
18.
《Nuclear Physics A》1999,650(2):227-244
We study Pb + Pb collisions at 158 A GeV/c using hydrodynamical approach. We test different equations of state (EoSs) and different initial conditions and show that there are more than one initial state for each EoS which reproduce the observed hadronic spectra. We also find that different equations of state favor different freeze-out temperature. Simultaneously we calculate the thermal dilepton and photon spectra for each EoS and initial state. We compare the dilepton mass spectrum to data measured by the CERES collaboration and find that the differences in spectra obtained using different EoSs and initial states are not resolvable within the current experimental resolution. However, at invariant masses over 2 GeV the difference in the yield due to various initial states is close to an order of magnitude. We also study the rapidity distribution of lepton pairs and find that for masses around 800 MeV the shape of the distribution depends strongly on the EoS. 相似文献
19.
C. Hartmann J. C. Latorre G. Ciccotti 《The European physical journal. Special topics》2011,200(1):73-89
The aim of this mini-review article is to clarify the relation between two distinct formulations of the thermodynamic free
energy for collective variables which can be found in the molecular dynamics literature. In doing so, we discuss the different
ensemble concepts underlying the two definitions and reveal their relation to strong confinement (restraints) and molecular
constraints. The latter analysis is based on a variant of Federer’s coarea formula which can be regarded as a generalization
of Fubini’s theorem for iterated integrals to curvilinear coordinates and which implies the famous “blue moon” ensemble identity
for computing conditional expectations using constrained simulations. For illustration we will present a few paradigmatic
examples. 相似文献
20.
A. Van Proeyen 《Nuclear Physics B》1980,174(1):189-206
In a search for the explanation of the finite quantum gravity corrections to anomalous moments we examined a spontaneous broken O(3) model with Yang-Mills particles and Higgs scalars coupled to gravitons. We found several new cancellations which prove that the coupling of all these particles together does not produce new counterterms apart from these which are known to exist in the subsystems and the cosmological term. The finiteness of the anomalous magnetic moment of a massive spin-1 particle is necessary for this to be valid. The finiteness of the anomalous quadrupole moment is a consequence of a known cancellation in the Einstein-Yang-Mills system. We also checked infrared finiteness and showed how to treat logarithmically divergent massless integrals in dimensional regularization. 相似文献