392 research outputs found
Structural-phase state and mechanical properties of submicrocrystalline titanium alloy Ti-6Al-4V obtained with use of reversible hydrogen alloying
Features of evolution of structural-phase state of titanium alloy Ti-6Al-4V at the process of submicrocrystalline structure formation using reversible hydrogen alloying have been investigated by methods of electron microscopic and X-ray diffraction analyses. Influence of hydrogen alloying on mechanical properties at stretching of submicrocrystalline titanium alloy Ti-6Al-4V in temperature interval of 293...1023 K was studied. Possible reasons of increase in ultimate and yield strength and reduction of deformation to destruction of submicrocrystalline alloy Ti-6Al-4V in temperature interval 873...1023 K at hydrogen alloying in quantity 0,08...0,33 mas. % were discusse
Levitation Simulator: Prototyping Ultrasonic Levitation Interfaces in Virtual Reality
We present the Levitation Simulator, a system that enables researchers and
designers to iteratively develop and prototype levitation interface ideas in
Virtual Reality. This includes user tests and formal experiments. We derive a
model of the movement of a levitating particle in such an interface. Based on
this, we develop an interactive simulation of the levitation interface in VR,
which exhibits the dynamical properties of the real interface. The results of a
Fitts' Law pointing study show that the Levitation Simulator enables
performance, comparable to the real prototype. We developed the first two
interactive games, dedicated for levitation interfaces: LeviShooter and
BeadBounce, in the Levitation Simulator, and then implemented them on the real
interface. Our results indicate that participants experienced similar levels of
user engagement when playing the games, in the two environments. We share our
Levitation Simulator as Open Source, thereby democratizing levitation research,
without the need for a levitation apparatus.Comment: 12 pages, 14 figures, CHI'2
The investigation of hydrogen accumulation in zirconium alloy by thermostimulated gas evolution method
Thermostimulated gas evolution from zirconium alloy saturated by hydrogen E_125 versus deformation degree has been studied. Samples of zirconium were subjected to straining with relative lengthening 2,5; 5,0 and 10,0 %, then they were saturated with hydrogen by electrolyte method at current density 0,5 A/sm2 during 4 hours. Or vice versa, they were first saturated with hydrogen being subjected to deformation afterwards. The deformation of alloy samples results in trap formation with different energies of hydrogen bond. In this case both bond energy and hydrogen quantity caught in traps depends on both deformation size and succession of «deformation-saturation» actions. The values of hydrogen bond energies in traps are estimated. Types of traps are defined
Halo Excitation of He in Inelastic and Charge-Exchange Reactions
Four-body distorted wave theory appropriate for nucleon-nucleus reactions
leading to 3-body continuum excitations of two-neutron Borromean halo nuclei is
developed. The peculiarities of the halo bound state and 3-body continuum are
fully taken into account by using the method of hyperspherical harmonics. The
procedure is applied for A=6 test-bench nuclei; thus we report detailed studies
of inclusive cross sections for inelastic He(p,p')He and
charge-exchange Li(n,p)He reactions at nucleon energy 50 MeV. The
theoretical low-energy spectra exhibit two resonance-like structures. The first
(narrow) is the excitation of the well-known three-body resonance. The
second (broad) bump is a composition of overlapping soft modes of
multipolarities whose relative weights depend on
transferred momentum and reaction type. Inelastic scattering is the most
selective tool for studying the soft dipole excitation mode.Comment: Submitted to Phys. Rev. C., 11 figures using eps
Optical-Model Description of Time-Reversal Violation
A time-reversal-violating spin-correlation coefficient in the total cross
section for polarized neutrons incident on a tensor rank-2 polarized target is
calculated by assuming a time-reversal-noninvariant, parity-conserving
``five-fold" interaction in the neutron-nucleus optical potential. Results are
presented for the system for neutron incident energies
covering the range 1--20 MeV. From existing experimental bounds, a strength of
keV is deduced for the real and imaginary parts of the five-fold
term, which implies an upper bound of order on the relative -odd
strength when compared to the central real optical potential.Comment: 11 pages (Revtex
Gamow-Teller strength in 54Fe and 56Fe
Through a sequence of large scale shell model calculations, total
Gamow-Teller strengths ( and ) in Fe and Fe are
obtained. They reproduce the experimental values once the operator
is quenched by the standard factor of . Comparisons are made with recent
Shell Model Monte Carlo calculations. Results are shown to depend critically on
the interaction. From an analysis of the GT+ and GT strength functions it is
concluded that experimental evidence is consistent with the sum rule.Comment: 6 pages, RevTeX 3.0 using psfig, 7 Postscript figures included using
uufile
The GAPS Programme with HARPS-N@TNG IX. The multi-planet system KELT-6: detection of the planet KELT-6 c and measurement of the Rossiter-McLaughlin effect for KELT-6 b
Aims. For more than 1.5 years we monitored spectroscopically the star KELT-6
(BD+312447), known to host the transiting hot Saturn KELT-6b, because a
previously observed long-term trend in radial velocity time series suggested
the existence of an outer companion. Methods. We collected a total of 93 new
spectra with the HARPS-N and TRES spectrographs. A spectroscopic transit of
KELT-6b was observed with HARPS-N, and simultaneous photometry was obtained
with the IAC-80 telescope. Results. We proved the existence of an outer planet
with a mininum mass Msini=3.710.21 M and a
moderately eccentric orbit () of period P3.5
years. We improved the orbital solution of KELT-6b and obtained the first
measurement of the Rossiter-McLaughlin effect, showing that the planet has a
likely circular, prograde, and slightly misaligned orbit, with a projected
spin-orbit angle =3611 degrees. We improved the KELT-6b
transit ephemeris from photometry, and we provided new measurements of the
stellar parameters. KELT-6 appears as an interesting case to study the
formation and evolution of multi-planet systems.Comment: Letter, 4 figures, accepted for publication in A&A. Some language
editing and numbering of the paper series changed (from X to IX
Do Hadronic Charge Exchange Reactions Measure Electroweak L = 1 Strength?
An eikonal model has been used to assess the relationship between calculated
strengths for first forbidden beta decay and calculated cross sections for
(p,n) charge exchange reactions. It is found that these are proportional for
strong transitions, suggesting that hadronic charge exchange reactions may be
useful in determining the spin-dipole matrix elements for astrophysically
interesting leptonic transitions.Comment: 14 pages, 5 figures, Submitted to Physical Review
Nuclear spin structure in dark matter search: The finite momentum transfer limit
Spin-dependent elastic scattering of weakly interacting massive dark matter
particles (WIMP) off nuclei is reviewed. All available, within different
nuclear models, structure functions S(q) for finite momentum transfer (q>0) are
presented. These functions describe the recoil energy dependence of the
differential event rate due to the spin-dependent WIMP-nucleon interactions.
This paper, together with the previous paper ``Nuclear spin structure in dark
matter search: The zero momentum transfer limit'', completes our review of the
nuclear spin structure calculations involved in the problem of direct dark
matter search.Comment: 39 pages, 12 figures, a review in revtex
Proton Elastic and Inelastic Scattering at Intermediate Energies from Isotopes of Oxygen and 9-Be as Part of a Unified Study of these Nuclei
This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit
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