8,657 research outputs found
Alfv\'en wave-driven wind from RGB and AGB stars
We develop a magnetohydrodynamical model of Alfv\'en wave-driven wind in open
magnetic flux tubes piercing the stellar surface of Red Giant Branch (RGB) and
Asymptotic Giant Branch (AGB) stars, and investigate the physical properties of
the winds. The model simulations are carried out along the evolutionary tracks
of stars with initial mass in the range of 1.5 to 3.0 and initial
metallicity =0.02. The surface magnetic field strength being set
to be 1G, we find that the wind during the evolution of star can be classified
into the following four types; the first is the wind with the velocity higher
than 80 km s in the RGB and early AGB (E-AGB) phases; the second is the
wind with outflow velocity less than 10 km s seen around the tip of RGB
or in the E-AGB phase; the third is the unstable wind in the E-AGB and
thermally pulsing AGB (TP-AGB) phases; the fourth is the stable massive and
slow wind with the mass-loss rate higher than 10 yr and
the outflow velocity lower than 20 km s in the TP-AGB phase. The
mass-loss rates in the first and second types of wind are two or three orders
of magnitude lower than the values evaluated by an empirical formula. The
presence of massive and slow wind of the fourth type suggests the possibility
that the massive outflow observed in TP-AGB stars could be attributed to the
Alfv\'en wave-driven wind.Comment: 17 pages, 15 figures, accepted for publication in Ap
Preparation And Characterization Of Composite Hollow Fiber Reverse Osmosis Membranes By Plasma Polymerization. 2. Reproducibility Of The Plasma Polymerization Process And Durability Of The Resulting Coated Membrane
The reproducibility of the plasma polymerization process was examined in a semicontinuous coating of hollow fibers, 6 fibers in lengths of approximately 12-15 m, by evaluating the performance of reverse osmosis membranes. The uniformity of the coating along the length of hollow fibers, as well as the reproducibility of the process, was found to be satisfactory when electrodes were conditioned in the actual conditions of plasma polymerization to be employed and plasma polymerization conditions were carefully controlled. The durability of the coated hollow fibers was then investigated in the following test media: hot water, low pH, high pH, and 0.1% NaOCl solutions. A threshold value of glow discharge parameter W/FM was found to be crucial In the performance of the reverse osmosis membrane and durability of the coated hollow fibers. Plasma polymerized composite membranes showed remarkable durability. © 1984, American Chemical Society. All rights reserved
Evaluation Of Plasma Polymers Of Silanes As Adhesion Promoters For Organic Paint
Plasma-polymerized coatings were prepared in a bell-jar-type reactor equipped with a magnetron system behind parallel aluminum electrodes using an a.c. source of frequency 10 kHz. Tetramethoxysilane, dimethyldimethoxysilane and hexamethyldisilane were used as monomers. Alkyd paint was coated on titanium plates onto which plasma polymer films had been deposited, to investigate the characteristics of the plasma-deposited films as adhesion promoters. The relationship between the adhesion strength for the paint and the conditions for the plasma polymerization was studied. The properties of the plasma polymers are dependent on the conditions of plasma polymerization manifested by two domains, namely the energy-deficient and the monomer-deficient regions. In the energy-deficient region, the differences due to the monomer structure can be clearly observed; however, in this region the adhesion of the plasma polymer film to the substrate metal is poor, and the plasma polymer does not serve as a good primer for the paint. In the monomer-deficient region (for this study a power input per unit mass of starting material of W/FM ≥ 1.7 x 109 J kg-1) improved adhesion of the paint is obtained; however, in this region the difference due to the monomer structure is found to be minimal. © 1984
Line nodes in the superconducting gap function of noncentrosymmetric CePt_3Si
The superconducting gap structure of recently discovered heavy fermion
CePt_3Si without spatial inversion symmetry was investigated by thermal
transport measurements down to 40 mK. In zero field a residual T-linear term
was clearly resolved as T-> 0, with a magnitude in good agreement with the
value expected for a residual normal fluid with a nodal gap structure, together
with a T^2-dependence at high temperatures. With an applied magnetic fields,
the thermal conductivity grows rapidly, in dramatic contrast to fully gapped
superconductors, and exhibits one-parameter scaling with T/sqrt{H}. These
results place an important constraint on the order parameter symmetry, that is
CePt_3Si is most likely to have line nodes.Comment: 5pages, 3figures, accpted for publication in Phys. Rev. Let
Spontaneous alloying in binary metal microclusters - A molecular dynamics study -
Microcanonical molecular dynamics study of the spontaneous alloying(SA),
which is a manifestation of fast atomic diffusion in a nano-sized metal
cluster, is done in terms of a simple two dimensional binary Morse model.
Important features observed by Yasuda and Mori are well reproduced in our
simulation. The temperature dependence and size dependence of the SA phenomena
are extensively explored by examining long time dynamics. The dominant role of
negative heat of solution in completing the SA is also discussed. We point out
that a presence of melting surface induces the diffusion of core atoms even if
they are solid-like. In other words, the {\it surface melting} at substantially
low temperature plays a key role in attaining the SA.Comment: 15 pages, 12 fgures, Submitted to Phys.Rev.
Systematic limits on sin^2{2theta_{13}} in neutrino oscillation experiments with multi-reactors
Sensitivities to sin^2{2theta_{13}} without statistical errors (``systematic
limit'') are investigated in neutrino oscillation experiments with multiple
reactors. Using an analytical approach, we show that the systematic limit on
sin^2{2theta_{13}} is dominated by the uncorrelated systematic error sigma_u of
the detector. Even in an experiment with multi-detectors and multi-reactors, it
turns out that most of the systematic errors including the one due to the
nature of multiple sources is canceled as in the case with a single reactor
plus two detectors, if the near detectors are placed suitably. The case of the
KASKA plan (7 reactors and 3 detectors) is investigated in detail, and it is
explicitly shown that it does not suffer from the extra uncertainty due to
multiple reactors.Comment: 26 pages, 10 eps-files, revtex
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