Your search for "A V Ognev" returned 178 results

We have studied the crystal structure, surface morphology, magnetic anisotropy, domain structure and tunnel magnetoresistance of spin-valves with a single and double MgO barrier layers. We have demonstrated the domain structure for soft and hard magnetic layers and observed significant changes after low temperature annealing. We have carried out magnetoresistance measurements using current-in-plane (CIP) four-probe technique and discovered a substantial difference in the values of TMR ratio for single and double MTJ spin-valves. It is shown that domain structure and magnetization reversal are the same for both systems, but otherwise the behavior of tunnel magnetoresistance is different, because of second MgO barrier effects on the system conductivity. The ability to manipulate the magnetization direction in MTJ systems using temperature annealing is demonstrated. It makes these structures possible for new applications in nanoelectronics as magnetic recording media and high sensitive sensors.

The outcomes of assessing the possibility of reducing the technogenic impact on the soil during field operations in crop production are presented by increasing the stability of the transport movement and technological means in agricultural fields. An increase in the number of passes, a distortion of the tramline shape, an increase in slippage, wobbling and sliding of technical equipment on the field lead to a significant deterioration in the topography and structure of the soil layer, which causes soil destruction and a decrease in its productivity. Transport work performed on agricultural fields leads to a significant negative technogenic impact on the soil due to the numerous passes, large transported weight, and the application of trailers. The impact on the stability of the road trains movement is considered in the paper. Characteristics of damped oscillations are used to evaluate the efficiency of impacts on stability. The method of changing the inclination angle of the turntable kingpin of the road train trailer is chosen by the method of influencing the movement stability. It is established that changing the inclination angle of the turntable kingpin of the road train trailer allows reducing the average amplitude of oscillations of the trailer front side by 26.5–28%, increasing the period of oscillations by 33.3%, and also slightly changing the decrement of oscillations by 0.5–2.5%. Therefore, structural changes in the towing device of vehicles, by providing better directional stability, will reduce the technogenic load on the soil: decrease compaction and destruction of the soil layer.

We report our experimental results on the structural and magnetic characteristics of nickel films electrodeposited on n-type (111) silicon substrates. Using scanning electron microscopy (SEM), magnetic force microscopy (MFM) and magnetic hysteresis loops, we indeed find a nominal thickness for transition from island to continuous film before which the magnetization of nanoparticles of Ni is represented by vortex states. The evidence of non-uniform ground states in Ni granules has been proofed by micromagnetic simulations. After the formation of a continuous film, stripe magnetic domains are formed with spontaneous in plane magnetization.

This paper is dedicated to a study of magnetic properties (magnetic anisotropy, coercive force and remanent magnetization) of spatially ordered high-density Ni nanowire arrays. The magnetic nanowires were prepared by electrodeposition of nickel from simple sulfate solutions into anodic aluminum oxide (AAO) nanoporous templates (with diameter of d = 20 and 40 nm) fabricated by potentiostatic anodization. We show that Ni nanowires have strong out-of-plane axial magnetic anisotropy (normal to the substrate plane) along with an in-plane anisotropy caused by hexagonal spatial distribution of nanowires in an array. An existence of the six-fold in-plane anisotropy proofs the long-range hexagonal order of nanowires. High quality of nanowire arrays makes possible of its usage as high-density (up to 2Tb/in²) magnetic recording media.

The approach based on synchrotron X-ray diffraction was applied in this research to investigate the dislocation and phase structures of severely deformed disk of Ti13Nb13Zr alloy. It was found, that the final structure of the material is inhomogeneous along the disk diameter. The local area of highest dislocation density of α'-phase matches with the zone of passed deformation-induced phase transformations.

Magnetoplasmonic crystals consisted of the combination of noble and ferromagnetic thin films deposited on diffraction gratings represent a special class of nanostructures that can utilize the magneto-optical Kerr effect enhanced by surface plasmon-polaritons excitation for the probing of an external DC magnetic field. Optical and magneto-optical properties of a magnetoplasmonic crystal are formed by magnetic behavior. This article represents ways to manipulate optical, magneto-optical and magnetic properties of nickel-based magnetoplasmonic crystals by the variation of the substrate parameters, the composition of magnetoplasmonic crystals as well as the compressive mechanical stresses on the surface of a ferromagnetic layer.

The paper considers one of the approaches to solving the problems of managing educational institutions of secondary vocational education, associated with the use of a digital platform. The capabilities of the digital platform in the implementation of the full cycle of educational process management are characterized. The features of five interrelated subsystems of the platform are presented: performance monitoring, methodological support, management of personalized educational trajectories, record of the academic achievements and employment promotion, virtual laboratory educational and research complexes. The principles of using the platform at two levels of management are described-the level of the educational organization and the level of the regional system of vocational education.

External and internal challenges facing the domestic system of vocational education today require structural and managerial changes in professional educational organizations that facilitate the adoption of effective timely management decisions and, at the same time, create conditions for the emergence of initiatives focused on the sustainable development of an educational organization including those related to the professional activities of teachers. The article deals with the management system of the educational process of vocational education from the classical theory of automatic control point of view. The structure of combined management, allowing to implement the management process of the educational organization of vocational secondary education, based on the process management model of the "Deming cycle" principle is proposed. The input and output parameters, control and setting actions are concretized. The implementation of control systems based on subsystems for monitoring the effectiveness of educational and methodological support activities and management, integrated into the digital educational platform of secondary vocational education, is proposed.

In the conditions of spring unheated greenhouses in the Rostov region on improved natural soils, the influence of the methods of tying tomato plants of various types of growth on the processes of crop formation and its quality indicators was assessed. The issues of the influence of methods of tying plants on the crop, its marketability, the share of early harvest and the average weight of the fruit are considered. It has been established that, on average, indeterminate hybrids, although they do not have a high total yield and the share of early production, however, have maximum marketability and average fruit weight. In determinant hybrids, the optimal combination of yield and quality was obtained from the Primadonna F₁ hybrid, for semi-determinant hybrids, for the Rozovyy nosik F₁ hybrid tied to twine, and for indeterminate hybrids, for the Makhitos F₁ hybrid, also tied to twine with a garter gun with a red ribbon for partial mechanization of the process.

In this paper, we conduct a mathematical analysis of the model of ensuring the road trains movement stability by changing the design of coupling devices to determine the critical characteristic parameters of the road trains, which result in the loss of en-route directional stability under external action. The concept of the model was to separate the process of yawing of the road trains and its elements (due to external perturbing action) on the highway into several typical stages. The main parameters of the stages (the displacement amplitude and rotation angle of the road trains elements in relation to the driving direction) were determined based on the initial conditions of the road trains movement, the force and duration of the external action. The most dangerous areas of external action application to the road trains were determined in this paper. The maximum permissible exposure limit should not exceed 0.5–1.0% of the road trains trailer momentum, with duration having the greater effect than the amount of impact. The results obtained can be used in mechanical engineering to improve the road trains performance.