91 research outputs found
Inclusion agglomeration in electrified molten metal: thermodynamic consideration
The effect of electric current on inclusion agglomeration in molten metal has been investigated. It is found that the agglomeration is dependent on the electric current density, distance between inclusions and orientation of electric field. Electric current retards the agglomeration unless two inclusions are aligned along or closely to the current flow streamlines and the distance between inclusions is less than a critical value. The mechanism is also validated in the computation of cluster agglomeration. The numerical results provide a comprehensive indication for the current-induced inclusion removal and current-induced inclusion elongation. When the inclusions are in long-thin shape, the calculation predicts the current-induced microstructure alignment and current-induced microstructure refinement phenomena
Reaction rate theory with account of the crystal anharmonicity
Reaction rate theory in solids is modified taking into account intrinsic
localized modes or discrete breathers (DBs) that can appear in crystals with
sufficient anharmonicity resulting in violation of Arrhenius law. Large
amplitude oscillations of atoms about their equilibrium positions in the
lattice cause local potentials of alternating sign, which are described in
terms of time-periodic modulations of the potential barriers for chemical
reactions taking place in the vicinity of DBs. The reaction rate averaged over
large macroscopic volumes and times including a lot of DBs is increased by a
factor that depends on the DB statistics. The breather statistics in thermal
equilibrium and in thermal spikes in solids under irradiation with swift
particles is considered, and the corresponding reaction rate amplification
factors are derived.Comment: 17 pages, 12 figure
Atmospheric bistatic communication channels with scattering. Part 2. Field Experiments in 2013
Results of field experiments on the influence of atmospheric conditions and some instrumental characteristics on the quality of information transfer in a bistatic optoelectronic communication system (OECS) operating in the visible wavelengths range are considered. The length of the atmospheric channel reached 17 km. Radiation of a copper bromide vapor laser with a wavelength of 510.6 nm was used as a signal source. It is shown that bistatic or over-the-horizon OECSs can operate both under the conditions of a cloudy and cloud-free atmosphere. Average values and standard deviations of communication errors were estimated under different atmospheric-optical conditions when some characteristics of individual instrumentation units varied
Absorption of Terahertz Radiation in Ge/Si(001) Heterostructures with Quantum Dots
The terahertz spectra of the dynamic conductivity and radiation absorption
coefficient in germanium-silicon heterostructures with arrays of Ge hut
clusters (quantum dots) have been measured for the first time in the frequency
range of 0.3-1.2 THz at room temperature. It has been found that the effective
dynamic conductivity and effective radiation absorption coefficient in the
heterostructure due to the presence of germanium quantum dots in it are much
larger than the respective quantities of both the bulk Ge single crystal and
Ge/Si(001) without arrays of quantum dots. The possible microscopic mechanisms
of the detected increase in the absorption in arrays of quantum dots have been
discussed.Comment: 9 pages, 4 figures; typos correcte
Electro-plastic effect on tensile deformation behaviour and microstructural mechanism of AZ31B alloy
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