Investigation of 2-D electromagnetic transients in a circular cylinder with time discontinuity in permittivity via the resolvent method

The resolvent method approach is proposed for analytically solving the time domain Volterra integral equation (TDVIE) which describes the electromagnetic fields in 2-D cylindrical structures with time changes in the permittivity. It is shown that the approach allows investigation of the electromagnetic field transformation due to an abrupt time change in dielectric permittivity inside a circular cylinder as well as the construction of the Green’s function for an initial-boundary value problem. Key mechanisms of electromagnetic field transformation are investigated and a qualitative distinction of the processes is shown that depends on an initial field configuration.     

Effective and flexible analysis for propagation in time varying waveguides

The equivalence between the propagation of dispersive modal fields in two-dimensional waveguides, and plane waves in a one-dimensional plasma is presented. Exploitation of this equivalence allows a time domain variant of the effective index approach to be used to model dispersive waveguides problems very efficiently. A time domain integral equation is developed for this important practical case and the stability of a computer algorithm based upon it is improved by means of both a semi-implicit formulation and the use of a modified space–time mesh.     

Accurate modelling of pulse transformation by adjustable-in-time medium parameters

A possibility of a strong change of an electromagnetic signal by a short sequence of time cycles of pulses that modulate the medium parameters is shown. The backward wave is demonstrated to be an inevitable result of the medium time change. Dependence of the relation between backward and forward waves on the parameters of the medium modulation is investigated. The finite statistical complexity of the electromagnetic signal transformed by a finite sequence of modulating cycles is calculated. Increase of the complexity with the number of cycles is shown.     

Transient Transformation of Whispering Gallery Resonator Modes Due to Time Variations in Dielectric Permittivity

This paper considers the switching effects on whispering gallery modes in circular dielectric resonators when their material is subject to abrupt time changes in permittivity. Both the transient response and the new steady-state regime are described in detail by means of an analytical approach.     

Identification of metastable states in peptide's dynamics

A recently developed spectral method for identifying metastable states in Markov chains is used to analyze the conformational dynamics of a four-residue peptide valine-proline-alanine-leucine. We compare our results to empirically defined conformational states and show that the found metastable states correctly reproduce the conformational dynamics of the system.     

Effect of pulsed excitation of a bounded medium on a plane electromagnetic wave

An analysis is made of the transformation of a plane monochromatic electromagnetic wave in response to a temporal change in the permittivity and conductivity of a semibounded medium. The change in the parameters of the medium takes the form of a rectangular pulse of arbitrary duration and amplitude. The detailed structure of the electric field and its evolutional redistribution are determined. The asymptotic formation of a backward wave is demonstrated, whose amplitude may exceed that of the primary wave for parameters typical of a semiconductor. Zh. Tekh. Fiz. 69, 84–92 (August 1999)     

Frequency change of partial spherical waves induced by time change of medium permittivity

The transformation of a plane harmonic wave caused by a time jump of the permittivity inside a dielectric sphere is investigated. The exact expressions for the transformed field are obtained as a solution of an initial and boundary value electromagnetic problem for the Maxwell’s equations based on the longitudinal and the transverse spherical vector functions.     

Molecular phase space transport in water: Non-stationary random walk model

Molecular transport in phase space is crucial for chemical reactions because it defines how pre-reactive molecular configurations are found during the time evolution of the system. Using Molecular Dynamics (MD) simulated atomistic trajectories we test the assumption of the normal diffusion in the phase space for bulk water at ambient conditions by checking the equivalence of the transport to the random walk model. Contrary to common expectations we have found that some statistical features of the transport in the phase space differ from those of the normal diffusion models. This implies a non-random character of the path search process by the reacting complexes in water solutions. Our further numerical experiments show that a significant long period of non-stationarity in the transition probabilities of the segments of molecular trajectories can account for the observed non-uniform filling of the phase space. Surprisingly, the characteristic periods in the model non-stationarity constitute hundreds of nanoseconds, that is much longer time scales compared to typical lifetime of known liquid water molecular structures (several picoseconds).