Bulletin of the Russian Academy of Sciences: Physics最新文献

The author considers three types of resonance of a classical coherent electromagnetic wave with the same carrier frequency as a quantum anharmonic oscillator, based on algebraic perturbation theory. The corresponding effective operators of the dipole moment of the anharmonic oscillator are obtained, allowing the polarization of the excited medium under the considered resonance conditions to be calculated. Some possibilities are established for the creation of nonlinear effects.

A study is performed of the magneto-optical Faraday effect of magnetic fluids based on MFe₂O₄ particles (M = Fe, Ni, Co) in which sodium oleate is used as dense surfactant. This allows Faraday rotation to be obtained at a low volume concentrations of these particles (0.25–0.5%). Rotation depends linearly on the strength of the magnetic field (500–1000 G), which is unsaturated up to 4000 G. The maximum effect is achieved for magnetic fluids based on CoFe₂O₄.

A methodology and a system are developed for complex remote diagnostics of insulation elements of high-voltage equipment of substations and power transmission lines, including suspended and through-pass insulators and supports. The system is based on the principle of simultaneously measuring and subsequently analyzing characteristics of partial discharges with high-frequency (400–800 MHz) and acoustic (30 kHz) sensors. The system is used to examine more than 50 specimens of polymer (LC 70/35) and porcelain (IOS 110/400) insulators in their operating mode. Amplitude-phase diagrams of partial discharge parameters are obtained that can be used to determine the type and degree of influence a defect has on the insulation. Features of defects are studied for 35 and 110 kV electrical networks.

Permalloy rod-shaped anisotropic nanoparticles have been used to study orientational relaxation in a polymethylsiloxane magnetic fluid. A magneto-rheological effect has been observed at different magnitudes and frequencies of the impact of a magnetic field, and the time of structural relaxation after removal of the field has been estimated.

The authors investigate the possibility of controlling the parameters of random number sequences using a continuous wavelet transform. It is shown that changing the energy of the scales of the continuous wavelet transform can increase the probability of passing the NIST LongestRun, FFT, and Runs tests. The possibility of increasing the probability of passing tests is demonstrated for different sizes of the studied experimental sequence of random numbers.

The authors study the effect detuning between the group velocities of two optical harmonics has on the reflection and transmission of radiation in a layered active quadratically nonlinear medium. The reflectance and transmittance at the fundamental and doubled frequencies are determined via numerical modeling. The soliton nature of energy transfer inside a medium is demonstrated.

Experimental results are presented on the formation of ordered structures of latex microparticles with diameters of 3 and 5 μm using arrays of point optothermal traps. The working area of the phase mask is divided into sub-elements to obtain the traps. A specific distribution of the phase delay of the prism (wedge) is specified for each trap.

It is shown that a scanning probe microscope allows precise manipulation of an ensemble of upconversion nanoparticles deposited uncontrollably on the surface of a glass substrate. The possibility of controlled movement of such particles over distances of several tens of micrometers is demonstrated, leaving several upconversion nanoparticles separated from others (or small conglomerates of them) on a surface with an area of ∼10⁴ μm². The system of marks on the substrate makes it easy to find such particles and perform a series of manipulations, including movements over submicrometer distances and rotation at a given angle of a single upconversion nanoparticle. The force of an individual upconversion nanoparticle’s adhesion to the surface of a substrate is estimated.

The authors consider using upconversion fluoride nanoparticles of NaYF₄ doped with Yb³⁺ and Er³⁺ ions as ordered non-invasive hidden labels. At the first stage the synthesized upconversion fluoride nanoparticles have been deposited from the suspension onto the substrate with mechanical scratches used as large-scale markers. The scanning probe microscope is then used to move individual upconversion nanoparticles macroscopically significant distances and deposit them in a controlled manner onto a clean surface, thereby imprinting nanoobjects. The displacement and deposition process has been monitored using a conventional optical microscope. Luminescent signals from regularly placed labels have been recorded in an optical confocal microscope.

Numerical modeling is used to show the possibility of forming (2D + 1) short-period (3‒5 oscillations under the envelope) light bullets in noncentrosymmetric media at the second harmonic generation with phase and group velocity detunings. Only up to certain intensities does cubic nonlinearity prevent the formation of space-time solitons.