249 research outputs found
Recrystallization and investigation of bismuth thin films by means of electron beam in transmission electron microscope
Thin bismuth films obtained by vacuum deposition were recrystallized under electron beam of scanning electron microscope at 5 kV and examined in a transmission electron microscope at 200 kV. In recrystallized films, various microstructures were detected: single-crystal, polycrystalline and amorphous regions, more or less faceted grains, single crystals and untransparent drop-shaped particles. In the crystallized film, a strong internal bending of the crystal lattice is detected, up to 110 deg/μm. © Published under licence by IOP Publishing Ltd.Partial support of project 3.6121.2017/8.9 (The Ministry of Education and Science of the Russian Federation) and Agreement No 02.A03.21.0006 (Act 211 Government of the Russian Federation) is acknowledged
Transitions between "" and "0" states in superconductor -- ferromagnet -- superconductor junctions
Experimental and theoretical study of superconductor (S) -- ferromagnet (F)
-- superconductor junctions showed that in certain range of parameters (e.g.,
the length of the ferromagnet , the exchange field, ) the
ground state of a SFS junction corresponds to superconducting phase difference
or 0. The phase diagram of a SFS junction with the respect to and 0
states is investigated in this letter in space. It is
shown that the phase diagram is very sensitive to the geometry of the system,
in particular, to the amount of disorder.Comment: Minor changes. References adde
Domain wall effects in ferromagnet-superconductor structures
We investigate how domain structure of the ferromagnet in
superconductor-ferromagnet heterostructures may change their transport
properties. We calculate the distribution of current in the superconductor
induced by magnetic field of Bloch domain walls, find the ``lower critical''
magnetization of the ferromagnet that provides vortices in the superconductor
Centers of crystallization in antimony thin films studied by transnission electron microscopy
We performed TEM studies of 7 crystallization centers using specially evaporated Sb thin films in finite areas. Strong internal lattice bending is revealed by use of the bend contour method.Partial support of project 3.6121.2017/8.9 (RF Ministry of Education and Science) and agreement № 02.A03.21.0006 (Act 211 Government of the RF) is acknowledged
On partial derivatives of multivariate Bernstein polynomials
It is shown that Bernstein polynomials for a multivariate function converge to this function along with partial derivatives provided that the latter derivatives exist and are continuous. This result may be useful in some issues of stochastic calculus
On Robustness of Discrete Time Optimal Filters
A new result on stability of an optimal nonlinear filter for a Markov chain with respect to small perturbations on every step is established. An exponential recurrence of the signal is assumed
Microwave-induced pi-junction transition in a superconductor / quantum-dot / superconductor structure
Using the nonequilibrium Green function, we show that microwave irradiation
can reverse the supercurrent flowing through a superconductor / quantum-dot /
superconductor structure. In contrast with the conventional sideband effect in
normal-metal / quantum-dot / normal-metal junctions, the photon-assisted
structures appear near ,
where is the resonant energy level of the quantum dot and is
the frequency of microwave field. Each photon-assisted structure is composed of
a negative and a positive peak, with an abrupt jump from the negative peak to
the positive peak around . The
microwave-induced -junction transition is interpreted in the picture of
photon-assisted Andreev bound states, which are formed due to multiple
photon-assisted Andreev reflection between the two superconductors. Moreover,
the main resonance located at can also be reversed with proper
microwave strength and frequency.Comment: 10 pagres, 3 figure
DETERMINATION OF THE ELECTRIC DRIVE POWER FOR LIGHTLY ARMORED CATERPILLAR AND WHEELED VEHICLES USING SINGLE- OR TWO-STAGE MECHANICAL GEARBOXES
When designing electromechanical transmissions (EMT) for lightly armored caterpillar and wheeled vehicles (LACWV), there is often a problem that the coefficient of adaptability of the traction motor (TM) at the minimum design power is not sufficient to meet the requirements for the power range of the transmission. In the literature, several ways have been worked out to solve this problem, however, there was not found a single algorithm allowing to formalize and step by step pass the process of choosing the most rational structure of the EMT. The purposeof the proposed work is the formation of scientifically based methodology for evaluating the possibility of using single-stage gearboxes in EMT for LACWV and calculation of the required TM power of the selected type for single- or two-stage mechanical gearboxes. Methodology. To carry out the research, the theory of motion of caterpillar and wheeled vehicles was used. Result. A formalized methodology for determining the required mechanical power of the electric drive for the LACWV is proposed, depending on the power capabilities of the motor-generator set, the torque characteristics of the selected TM and the number of stages in the mechanical gearboxes. Scientific novelty. For the first time, a formalized connection has been established between the tactical and technical requirements for LACWV, the characteristics of the selected TM, the structure and parameters of the mechanical gearboxes. Practical value. The toolkit for the engineering and design personnel developing the EMT for the LACWV was obtained. Work with the algorithm is illustrated by the example of power selection and gear ratios of mechanical gearboxes for the multi-purpose lightly armored caterpillar tractor MT-LB
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