Recent development of quasiclassical operator method

Eigenfunction expansions for the equations of crystal optics in a half-space

1. The impulse activity of single nerve fibers supplying the ampullae of Lorenzini in hyoid group of the Black Sea skate, was recorded to study the response of these receptors to various modifications of stimulation with the vertical component of a magnetic field. 2. When the animal was at rest in motionless water an impulse reaction was observed only with changes in magnetic field, a constant field had no effect. The intensity of response was determined by the rate of magnetic field change (dB/dt). 3. The nature of responses to magnetic field changes depended on the orientation of the ampullary canals relative to induced currents in the animal's body and in the surrounding sea water (Figs. 1, 2 and 3). 4. The intensity of response of a single receptor to magnetic field changes decreased with the shortening of the ampullary canal under study (Fig. 4); cutting of the other canals or dissection of the capsule of the ampullary cluster appeared to have no effect. 5. The receptors of the ampullae of Lorenzini were shown to respond to a constant magnetic field when the fish moved in water, or when water was moved with respect to the fish (Figs. 5 and 6). 6. The character of impulse responses to a constant magnetic field depended on the direction of the field and the direction of movement of either the fish or the water. The relationship between the response intensity and magnetic field, or velocity of water flow is roughly linear (Figs. 7 and 8). 7. Symmetrical receptors on the right and left sides of the animal's body responded oppositely to stimulation by either increasing or constant magnetic field (Figs. 1 and 6). 8. Experiments involving compensation for the Earth's magnetic field with Helmholtz coils revealed a statistically significant reaction to the vertical component of the geomagnetic field (0.35 Gs in the region of the Karadag Biological Station, the Crimea). 9. The mechanisms and functional role of the detection of changing and constant magnetic field by the ampullae of Lorenzini are discussed.

For the original article see ibid., vol.MTT-34, no.1, p.161-7 (1986). The commenters cite a previously published work which contains some solutions which are identical to those found in the above-titled work. In replying, the authors agree that the solutions are identical and express appreciation for having the previously published work called to their attention.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

In this work, two-dimensional periodic and quasi-periodic non-diffractive spatial inhomogeneous polarization optical fields are generated, numerically and experimentally, by the superposition of multiple plane waves with different polarizations. For the experimental implementation of the fields, synthetic phase holograms are employed in conjunction with half-wave and quarter-wave retarder films as polarization modulators. The obtained spatially inhomogeneous polarization optical fields show good quality and are in good agreement with numerical results. The proposed method is highly efficient for the generation of these types of optical fields.

In this paper, we derive a quantitative model for the manipulation of superparamagnetic particles by superposition of a homogeneous magnetic field and magnetic field gradients. Our results show that by this combination, the magnitude as well as the sign of the force on a magnetic particle can be controlled. By quantitatively modeling the magnetic force on a representative superparamagnetic particle, we find that for a common lab-on-chip scenario large repulsive forces can be achieved by adding a homogeneous field perpendicular to the plane of the chip. This offers new perspectives for the on-chip manipulation of magnetic particles. As a first example, in-plane positioning of particles with an accuracy of ~1 μm is experimentally demonstrated.

Problem statement. In electric and hybrid transport, passengers sit very close to the electrical system of considerable power, usually for a considerable time. People are concerned about the level of frequency, intensity of electromagnetic radiation, and the time spent in transport. The relatively high currents achieved in these systems and the short distances between power devices and passengers mean that the latter can be exposed to the corresponding magnetic fields. This means that there is a need to assess the electromagnetic environment inside these vehicles before they are put on the market. When designing electric and hybrid vehicles and their components, it is necessary to take into account the hazards of magnetic field exposure to drivers, passengers and the environment. The aim is to study the effect of electromagnetic radiation on people and improve the efficiency of vehicle operation by assessing the electromagnetic safety of electric and hybrid vehicles at the stage of their operation, as well as to improve methods for assessing electromagnetic radiation depending on operating conditions. Methodology. Methods are a systematic approach to research, protection against electromagnetic radiation in transport, conducting measurements of electromagnetic radiation in electric and hybrid transport, finding out the spatially strong inhomogeneity of the magnetic field and building 3D topology using numerous uniformly distributed magnetic field sensors in the vehicle interior, i.e. by a differential phase-gradient method for the study of ultra-low frequency amplifiers from 0.001 - 100 Hz of geomagnetic variations, a method of testing magnetic fields. This method allows using three three-component magnetic sensors arranged in a triangle at a short distance from each other (magnetic gradiometer) to construct a vector of gradients and phase velocities of magnetic variations for any of the three components of magnetic fields. As a result, the phase-gradient method has found its application for measuring magnetic fields in electric and hybrid vehicles, as well as for detecting the topology of magnetic fields, taking into account their extreme spatial heterogeneity, the sensors in the cabin should be located quite densely, i.e., the number of sensors should be at least 10-20 (evenly at a distance of ten centimeters at floor level, at head level of drivers and passengers, etc.). Scientific novelty: the study of electrical equipment in electric and hybrid transport has shown that the source of electromagnetic fields, which have a strong temporal and spatial heterogeneity in the frequency range from 0 to hundreds of megahertz, that they are a superposition of fields from many sources (from electric motors, traction batteries, live elements, various electrical equipment (starting and braking resistance, group switches, rheostat units, electrical circuits for ventilation, lighting, heating, etc.). Practical relevance. The problems of determining the moment of occurrence of electromagnetic hazards in electric and hybrid vehicles are considered. It is established that electronic devices on board are usually higher in frequency than magnetic fields, which is associated with changes in traffic modes. Safety measures against electromagnetic radiation in electric and hybrid modes of transport are presented.

Long wavelength vibrational modes in the ferromagnetic semiconductor Ga_{0.91}Mn_{0.09}As are investigated using time resolved x-ray diffraction. At room temperature, we measure oscillations in the x-ray diffraction intensity corresponding to coherent vibrational modes with well-defined wavelengths. When the correlation of magnetic impurities sets in, we observe the transition of the lattice into a disordered state that does not support coherent modes at large wavelengths. Our measurements point toward a magnetically induced broadening of long wavelength vibrational modes in momentum space and their quasilocalization in the real space. More specifically, long wavelength vibrational modes cannot be assigned to a single wavelength but rather should be represented as a superposition of plane waves with different wavelengths. Our findings have strong implications for the phonon-related processes, especially carrier-phonon and phonon-phonon scattering, which govern the electrical conductivity and thermal management of semiconductor-based devices.

Ultrasonic scattering by a side-drilled hole

A new derivation for the radiation reaction on a point charge is presented. The field of the charge is written as a superposition of plane waves. The plane wave spectrum of the field consists of homogeneous plane waves which propagate away from the charge at the speed of light, and inhomogeneous plane waves which constitute the Coulomb field of the point charge. The radiation field is finite at the orbit of the point charge. The force acting on the charge due to this field is the well known Abraham-Lorentz radiation reaction.

Users data of usage and the number of devices connected to the network are increasing from years to years, simply, the internet usage is growing. Due to this phenomenon, we need a decent channel capacity to keep up with it. One of the channel characteristics that affects to the capacity is channel coefficient. By this relation, we could enlarge the channel capacity by improving its channel coefficient. In this research, we conducted an analysis towards the maximum and minimum values of a channel coefficient, simultaneously defined by upper and lower threshold. The simulation on this research is using superposition of plane wave as the basic model. Previously, this model had been used on pCell technology to enlarge the multiplexing gain. However, on this research, we conducted a different approach by using the model to achieve the maximum and minimum value of the channel coefficient. At the end, we found a relation between the upper and lower threshold formulation and the channel coefficient simulation on some signal paths, with their direction randomized by uniform distribution.

The chiral magnet Cu_{2}OSeO_{3} hosts a Skyrmion lattice that may be equivalently described as a superposition of plane waves or a lattice of particlelike topological objects. A thermal gradient may break up the Skyrmion lattice and induce rotating domains, raising the question of which of these scenarios better describes the violent dynamics at the domain boundaries. Here, we show that in an inhomogeneous temperature gradient caused by illumination in a Lorentz transmission electron microscope different parts of the Skyrmion lattice can be set into motion with different angular velocities. Tracking the time dependence, we show that the constant rearrangement of domain walls is governed by dynamic 5-7 defects arranging into lines. An analysis of the associated defect density is described by Frank's equation and agrees well with classical 2D MonteCarlo simulations. Fluctuations of boundaries show a surgelike rearrangement of Skyrmion clusters driven by defect rearrangement consistent with simulations treating Skyrmions as point particles. Our findings underline the particle character of the Skyrmion.

Summary Seismic waves obey the wave equation, and low-frequency EM waves obey the diffusion equation. Despite this, there is a deep similarity in their properties. Both wave types may be analyzed as a superposition of plane waves which are both dispersive and attenuative; the principal difference is that for seismics, these effects are weak, whereas for EM, they are strong. This means that all seismic processing algorithms which do not assume low dispersion and attenuation may be used to process properly acquired EM data; this is the majority of the seismic toolkit. In particular, EM data may be imaged, seismic-style, rather than mathematically inverted, EM style. With both data-types, the signal from the subsurface is weak, so it is best to detect it without competition from a concurrent source. This means that controlled sources of EM should be impulsive sources (“ISEM”) rather than continuous sources (“CSEM”). At low frequency, the EM phase velocity is a few km/s, comparable to seismic velocities. Hence, seismic-style acquisition, including the measurement of moveout, is feasible for EM data. For seismics, the Quality factor Qseis is a large material property, to be determined from the data; whereas QEM= ½ is a property of the equation.

In the study of E region irregularities the standard procedure is to Fourier analyze the irregularities in both time and space, that is, to describe them as a superposition of plane waves. This introduces difficulties when the amplitude of the plane waves becomes large, thereby adding nonlinear terms to the original equations and forcing all the plane waves to become coupled to one another. In the present work we stay away from Fourier analysis and use the standard fluid description of the instabilities in the limit of perturbed electric fields that are strictly perpendicular to the geomagnetic field. We obtain a nonlinear generalization of the standard results whereby the diffusion‐like operator found in linear theory is now a function of the density itself. Therefore, as the structures grow, the net electric field seen by the ambient plasma inside the structures changes in time: it rotates and its amplitude decreases. Consequently, one possible saturation mechanism for the instabilities is a reduction in the net electric field inside the structures, which brings them to threshold velocity conditions. This being stated, other nonlinear saturation mechanisms remain possible if they require smaller saturation amplitudes than the present work. Either way, our work is consistent with intermittency and implies that the largest amplitude structures in the medium should be rotated away from zero flow angle conditions by a measurable amount. Finally, we show that when compared to an irregularity‐free situation, there should be a measurable reduction in the average Hall current carried by the plasma, while the average Pederseri current should not be affected.

The aim of this study is to engage a basic understanding of the information micro-Raman spectroscopy may yield when this characterization tool is applied to carbon nanotubes. All collective vibrations that occur in crystals can be viewed as the superposition of plane waves, called phonons, that virtually propagate to infinity. The two dominant Raman features are the radial breathing mode at low frequencies, the tangential G band and the D band multi-feature at higher frequencies. Carbon nanotubes (CNT) were formed by double furnace chemical vapor deposition. This method was based on the pyrolysis of liquid aerosols containing hydrocarbons as carbon source (camphor oil), ferrocene as the catalyst source and nitrogen as the carrier gas. The samples were prepared by placing the carbon precursor on the alumina boat into the first furnace which contains the catalyst source at different alumina boat heated at 200 °C and passed through the deposition furnace. The deposition furnace was heated at 500-900°C for 1 hour depositing CNT without annealing treatment. Then, the samples were characterized using micro-Raman spectrometer obtaining the carbon G and D peaks around 1580 cm1 and 1350 cm1 respectively and the image of the CNT produced were obtained from field emission scanning electron microscope and high resolution transmission electron microscope. Keywords: micro-Raman spectroscopy, Carbon nanotubes, Camphor oil

In this paper, a straightforward approach is presented to generate Bessel beam sources in three-dimensional finite-difference time-domain (FDTD) method. Based on the angular spectrum representation (ASR), the incident Bessel beam is described as a superposition of plane waves whose wavevectors covering a conical surface. This decomposition of Bessel beam is then approximated by a finite collection of plane waves, which are injected into FDTD simulation domain using the total-field/scattered-field (TF/ST) method. The present method's correctness and accuracy are verified by comparing the reconstructed field in FDTD with the original field. Far-field scattered diagrams of a dielectric sphere and a spheroid particle illuminated by a zero-order or a higher-order Bessel beam are calculated using FDTD. The results are compared with those calculated using the generalized Lorenz-Mie theory (GLMT) and surface integral equation method (SIEM). Very good agreements have been achieved, which partially indicate the correctness of our method. Internal and near-surface field distributions for a two-layer hemisphere particle, which are illuminated by Bessel beams, are also displayed to show the potentials of this approach in solving scattering problems of complex particles. This approach can also be applied to generate other structured beam sources in FDTD, which provides an access to solve structured beam scattering by complex particles using FDTD.