583 research outputs found
Development of a Technique and Method of Testing Aircraft Models with Turboprop Engine Simulators in a Small-scale Wind Tunnel - Results of Tests
This report presents the results of experimental investigations into the interaction between the propellers (Ps) and the airframe of a twin-engine, twin-boom light transport aircraft with a Ξ -shaped tail. An analysis was performed of the forces and moments acting on the aircraft with rotating Ps. The main features of the methodology for windtunnel testing of an aircraft model with running Ps in TsAGIβs T-102 wind tunnel are outlined.The effect of 6-blade Ps slipstreams on the longitudinal and lateral aerodynamic characteristics as well as the effectiveness of the control surfaces was studied on the aircraft model in cruise and takeoff/landing configurations. The tests were conducted at flow velocities of Vβ = 20 to 50 m/s in the ranges of angles of attack Ξ± =Β -6 to 20 deg, sideslip angles of Ξ² = -16 to 16 deg and blade loading coefficient of B 0 to 2.8. For the aircraft of unusual layout studied, an increase in blowing intensity is shown to result in decreasing longitudinal static stability and significant asymmetry of the directional stability characteristics associated with the interaction between the Ps slipstreams of the same (left-hand) rotation and the empennage
Multifragmentation in Collisions of 4.4gev-Deuterons with Gold Target
The relative velocity correlation function of pairs of intermediate mass
fragments has been studied for d+Au collitions at 4.4 GeV. Experimental
correlation functions are compared to that obtained by multibody Coulomb
trajectory calculations under the assumption of various decay timees of the
fragmenting system. The combined approach with the empirically modified
intranuclear cascade code followed by the statistical multifragmentation model
was used to generate the starting conditions for these calculations. The
fragment emossion time is found to be less than 40 fm/c.Comment: Accepted for publication in Bulletin of the Russian Academy of
Sciences. Physic
Spin waves in diluted magnetic quantum wells
We study collective spin excitations in two-dimensional diluted magnetic
semiconductors, placed into external magnetic field. Two coupled modes of the
spin waves (the electron and ion modes) are found to exist in the system along
with a number of the ion spin excitations decoupled from the electron system.
We calculate analytically the spectrum of the waves taking into account the
exchange interaction of itinerant electrons both with each other and with
electrons localized on the magnetic ions. The interplay of these interactions
leads to a number of intriguing phenomena including tunable anticrossing of the
modes and a field-induced change in a sign of the group velocity of the ion
mode
High-temperature Aharonov-Bohm-Casher interferometer
We study theoretically the combined effect of the spin-orbit and Zeeman
interactions on the tunneling electron transport through a single-channel
quantum ring threaded by magnetic flux. We focus on the high temperature case
(temperature is much higher than the level spacing in the ring) and demonstrate
that spin-interference effects are not suppressed by thermal averaging. In the
absence of the Zeeman coupling the high-temperature tunneling conductance of
the ring exhibits two types of oscillations: Aharonov-Bohm oscillations with
magnetic flux and Aharonov-Casher oscillations with the strength of the
spin-orbit interaction. For weak tunneling coupling both oscillations have the
form of sharp periodic antiresonances. In the vicinity of the antiresonances
the tunneling electrons acquire spin polarization, so that the ring serves as a
spin polarizer. We also demonstrate that the Zeeman coupling leads to
appearance of two additional peaks both in the tunneling conductance and in the
spin polarization
In situ X-ray diffraction investigation of nitride coatings at high-temperature oxidation
Structural and phase researches of the multicomponent nanocrystalline coatings synthesized by plasma-assisted vacuum arc method at high-temperature influence by method of X-ray diffraction with the use of synchrotron radiation in situ have been carried out. The main features of these coatings are the superhardness (39 - 45 GPa) and nanocrystalline structure (5 - 20 nm). The analysis of results of structural and phase researches, physical and mechanical characteristics after oxidation of multicomponent nitride coatings at high-temperature heating in open air is presented
ΠΠΎΡΡΠΎΠ»ΠΎΠ³ΠΈΡ ΡΠΏΠΎΡ Parahemionitis arifolia (Cheilanthoideae, Pteridaceae)
A study of spores of the single species of the genus Parahemionitis Panigrahi was performed using the method of scanning electronic microscopy (SEM). Spores of Parahemionitis arifolia (Burm. f.) Panigrahi are tetrahedral trilete, roundish-triangular in polar position, with micro-wrinkled exospore and sculptured perispore. Sculpture of perispore is cristate-reticulate, cristae are quite regularly distributed and form reticulum with small mostly closed polygonal luminae of different shape. Laesura arms are often obscured by numerous cristae. Size of spores is 53β63 Γ 40β42 ΞΌm. Spores of P. arifolia are similar in perispore sculpture with those of species of some cheilanthoid ferns
ΠΠΎΠ½ΡΠΏΠ΅ΠΊΡ ΡΠΎΠ΄Π° Anopteris (Pteridophyta, Pteridaceae)
In the article a synopsis of the genus Anopteris (Prantl) Diels is given. The synopsis of Anopteris includes three species. For each species, the Latin name, basionym, nomenclatural citation, synonyms, information on locus classicus, type, habitat, and distribution are given. AnΒ original key for identification of the species of Anopteris is also prepared. The localities of occurrence of each species are precisely given.Β ΠΡΠΈΠ²Π΅Π΄Π΅Π½ ΠΊΠΎΠ½ΡΠΏΠ΅ΠΊΡ ΡΠΎΠ΄Π° Anopteris (Prantl) Diels. ΠΠΎΠ½ΡΠΏΠ΅ΠΊΡ Π²ΠΊΠ»ΡΡΠ°Π΅Ρ ΡΡΠΈ Π²ΠΈΠ΄Π°. ΠΠ»Ρ ΠΊΠ°ΠΆΠ΄ΠΎΠ³ΠΎ ΠΈΠ· Π½ΠΈΡ
ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡΡΡ Π»Π°ΡΠΈΠ½ΡΠΊΠΎΠ΅ Π½Π°Π·Π²Π°Π½ΠΈΠ΅, Π±Π°Π·ΠΈΠΎΠ½ΠΈΠΌ, Π½ΠΎΠΌΠ΅Π½ΠΊΠ»Π°ΡΡΡΠ½Π°Ρ ΡΠΈΡΠ°ΡΠ°, ΡΠΈΠ½ΠΎΠ½ΠΈΠΌΡ, ΠΎΡΠΊΡΠ΄Π° ΠΎΠΏΠΈΡΠ°Π½, ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΡ ΠΎ ΡΠΈΠΏΠ΅, Π΄Π°Π½Π½ΡΠ΅ ΠΎ ΠΌΠ΅ΡΡΠΎΠΎΠ±ΠΈΡΠ°Π½ΠΈΠΈ, ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½ΠΈΠ΅ ΠΏΠΎ ΡΡΡΠ°Π½Π°ΠΌ Ρ ΡΠΈΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΌΠ΅ΡΡ ΡΠ±ΠΎΡΠ° ΠΈ ΠΎΠ±ΡΠ΅Π΅ ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½ΠΈΠ΅. ΠΠ»Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ Π²ΡΠ΅Ρ
Π²ΠΈΠ΄ΠΎΠ² ΡΠΎΠ΄Π° Anopteris ΡΠΎΡΡΠ°Π²Π»Π΅Π½ ΠΎΡΠΈΠ³ΠΈΠ½Π°Π»ΡΠ½ΡΠΉ ΠΊΠ»ΡΡ, ΡΠΊΠ°Π·Π°Π½Ρ ΠΏΠΎΠ΄ΡΠΎΠ±Π½ΡΠ΅ ΠΌΠ΅ΡΡΠ° ΠΏΡΠΎΠΈΠ·ΡΠ°ΡΡΠ°Π½ΠΈΡ.Β ΠΡΠΈΠ²Π΅Π΄Π΅Π½ ΠΊΠΎΠ½ΡΠΏΠ΅ΠΊΡ ΡΠΎΠ΄Π° Anopteris (Prantl) Diels. ΠΠΎΠ½ΡΠΏΠ΅ΠΊΡ Π²ΠΊΠ»ΡΡΠ°Π΅Ρ ΡΡΠΈ Π²ΠΈΠ΄Π°. ΠΠ»Ρ ΠΊΠ°ΠΆΠ΄ΠΎΠ³ΠΎ ΠΈΠ· Π½ΠΈΡ
ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡΡΡ Π»Π°ΡΠΈΠ½ΡΠΊΠΎΠ΅ Π½Π°Π·Π²Π°Π½ΠΈΠ΅, Π±Π°Π·ΠΈΠΎΠ½ΠΈΠΌ, Π½ΠΎΠΌΠ΅Π½ΠΊΠ»Π°ΡΡΡΠ½Π°Ρ ΡΠΈΡΠ°ΡΠ°, ΡΠΈΠ½ΠΎΠ½ΠΈΠΌΡ, ΠΎΡΠΊΡΠ΄Π° ΠΎΠΏΠΈΡΠ°Π½, ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΡ ΠΎ ΡΠΈΠΏΠ΅, Π΄Π°Π½Π½ΡΠ΅ ΠΎ ΠΌΠ΅ΡΡΠΎΠΎΠ±ΠΈΡΠ°Π½ΠΈΠΈ, ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½ΠΈΠ΅ ΠΏΠΎ ΡΡΡΠ°Π½Π°ΠΌ Ρ ΡΠΈΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΌΠ΅ΡΡ ΡΠ±ΠΎΡΠ° ΠΈ ΠΎΠ±ΡΠ΅Π΅ ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½ΠΈΠ΅. ΠΠ»Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ Π²ΡΠ΅Ρ
Π²ΠΈΠ΄ΠΎΠ² ΡΠΎΠ΄Π° Anopteris ΡΠΎΡΡΠ°Π²Π»Π΅Π½ ΠΎΡΠΈΠ³ΠΈΠ½Π°Π»ΡΠ½ΡΠΉ ΠΊΠ»ΡΡ, ΡΠΊΠ°Π·Π°Π½Ρ ΠΏΠΎΠ΄ΡΠΎΠ±Π½ΡΠ΅ ΠΌΠ΅ΡΡΠ° ΠΏΡΠΎΠΈΠ·ΡΠ°ΡΡΠ°Π½ΠΈΡ.
Use of superplastic deformation and diffusion welding to form a tee designed with a complex set of internal stiffening elements
Role of magnetic degrees of freedom in a scenario of phase transformations in steel
The diversity of mesostructures formed in steel at cooling from a
high-temperature austenite ("gamma") phase is determined by the interplay of
shear reconstructions of crystal lattice and diffusion of carbon. Combining
first-principles calculations with large-scale phase-field simulations we
demonstrate a decisive role of magnetic degrees of freedom in the formation of
energy relief along the Bain path of "gamma"-"alpha" transformation and, thus,
in this interplay. We show that there is the main factor, namely, the magnetic
state of iron and its evolution with temperature which controls the change in
character of the transformation. Based on the computational results we propose
a simple model which reproduces, in good agreement with experiment, the most
important curves of the phase transformation in Fe-C, namely, the lines
relevant to a start of ferrite, bainite, and martensite transformations.
Phase-field simulations within the model describe qualitatively typical
patterns at these transformations
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