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Vol 61, No 4 (2016)
- Year: 2016
- Articles: 12
- URL: https://journals.rcsi.science/1028-3358/issue/view/11993
Physics
Investigation of frequency-selective devices based on a microstrip 2D photonic crystal
Abstract
The frequency-selective properties of structures based on a 2D microstrip photonic crystal have been investigated theoretically and experimentally. It is shown that various microwave devices, including diplexers, bandpass filters, and double bandpass filters, can be designed based on these structures.
155-159
Sensitivity of the optical absorption method based on instrumental selection of Fourier components of the absorption spectrum
Abstract
A new analytical method of optical absorption analysis, based on selection of a Fourier component of the absorption spectrum (characteristic of the material under study) by a polarization interference filter, has been proposed and tested experimentally.
160-163
Coherent and non-coherent components of two-photon Rydberg excitation of ultracold Li7 atoms
Abstract
A study of the optical spectra of ultracold highly excited Li7 atoms has revealed coherent and non-coherent components of two-photon excitation. The high sensitivity of the method makes it possible to record pure coherent resonances at a detuning of 803.5 MHz from the intermediate 2P3/2 resonance.
164-167
Multifunctional phenomena in sublimed dysprosium in high magnetic fields: The magnetocaloric effect and magnetostriction
Abstract
With the use of sublimed dysprosium having a controllable impurity composition, two physical functional phenomena induced by a magnetic field are studied: magnetostriction and the magnetocaloric effect, which is estimated by independent direct and indirect methods. A giant magnetostriction value at the “order–order” magnetic phase transition and a large magnetocaloric effect in high magnetic fields at the “order–disorder” transition are shown. Both phenomena are discussed in relation to the complex field and temperature behavior of metallic-dysprosium magnetization, the measurement of which is carried out in wide intervals of temperature and magnetic fields (to 14 T).
168-171
Anisotropic spectra of ultrasonic attenuation in aqueous dispersions with oriented carbon nanotubes
Abstract
The method of acoustic spectroscopy is used for the first time for investigating the spectra of ultrasonic attenuation in the range of 3–100 MHz on oriented carbon nanotubes in the stabilized aqueous dispersion. The anisotropy of attenuation of ultrasound manifests itself in a significant distinction between the attenuation spectra for preferential perpendicular and parallel orientation of carbon nanotubes with respect to the wave-propagation direction. A qualitative agreement of the measured-spectra shape with that of the attenuation spectra calculated from the theoretical model is obtained.
172-174
The duality principle and inversion of Laplace–Stielties transforms
Abstract
The fundamental relation between the Laplace transform, the Stielties transform, and the generalized integral equation of refraction is revealed, and a duality principle is formulated for the solution of inverse problems of radio physics. New formulas of the Laplace-transform inversion satisfying the duality principle are obtained. There is no necessity of contour integration in a complex plane for the relations found, which considerably simplifies the reconstruction of originals and makes it possible to control systematic errors in the experimental data.
175-178
Technical Physics
Statistical synthesis of multiantenna ultrawideband radiometric complexes
Abstract
An optimum signal processing algorithm of radiometric imaging has been synthesized for the first time using multiantenna ultrawideband (UWB) radiometric complexes (RMCs). Radiometric images (RMI) are interpreted physically as intensity depending on the angular coordinates or the spectral radio brightness averaged in the operation frequency band. In accordance with the synthesized algorithm, a structural scheme of ultrawideband radiometric complexes has been developed. An analytical expression for the ambiguity function of radiometric complexes has been obtained. The ambiguity function is modeled in the case of processing narrowband and ultrawideband radiometric signals. As follows from the analysis of the results, new elements of the theory of optimum processing of UWB radiometric signals with the involvement of multielement antenna systems are an important tool in creating highly accurate, biologically and ecologically safe complexes for studying various media and objects.
179-183
Mechanics
184-187
Properties of “started” earthquakes
Abstract
The properties of earthquakes called “started” in [1] are studied. The problems associated with the method of revealing them, the expected behavior of the event, and the determination of its place, time, and intensity are discussed. Certain characteristic properties of real earthquakes are compared with the modeled ones. It is emphasized that there are no data on earthquakes of a similar type in scientific publications. The method of using high-efficiency calculations is proposed by imbedding the investigations in topological spaces having a wider spectrum of properties than the functional ones.
188-191
Direct pore-scale flow simulation using quasi-hydrodynamic equations
Abstract
The use of the set of quasi-hydrodynamic equations for mathematical simulation of flows of a viscous heat-conducting compressible fluid in digital samples of rocks is considered. On the basis of a computation experiment, the permeability coefficient is determined.
192-194
Deformation of a water shell during free fall in air
Abstract
The basic regularities of the change in the shape and sizes (the initial volume is 0.05–0.5 L) of a water shell are singled out in its deformation during free fall in air from a height of 3 m. The 3D recording of the basic stages of deformation (flattening of the shell, nucleation, growth, and destruction of bubbles, formation of the droplet cloud) is carried out using high-speed (up to 105 frames per second) Phantom V411 and Phantom Miro M310 video cameras and the program complex Tema Automotive (with the function of continuous tracking). The physical model of destruction of large water bodies is formulated at free fall with the formation of the droplet cloud.
195-200
201-205