751 research outputs found
Magneto-hydrodynamic Simulations of a Jet Drilling an HI Cloud: Shock Induced Formation of Molecular Clouds and Jet Breakup
The formation mechanism of the jet-aligned CO clouds found by NANTEN CO
observations is studied by magnetohydrodynamical (MHD) simulations taking into
account the cooling of the interstellar medium. Motivated by the association of
the CO clouds with the enhancement of HI gas density, we carried out MHD
simulations of the propagation of a supersonic jet injected into the dense HI
gas. We found that the HI gas compressed by the bow shock ahead of the jet is
cooled down by growth of the cooling instability triggered by the density
enhancement. As a result, cold dense sheath is formed around the interface
between the jet and the HI gas. The radial speed of the cold, dense gas in the
sheath is a few km/s almost independent of the jet speed. Molecular clouds can
be formed in this region. Since the dense sheath wrapping the jet reflects
waves generated in the cocoon, the jet is strongly perturbed by the vortices of
the warm gas in the cocoon, which breaks up the jet and forms a secondary shock
in the HI-cavity drilled by the jet. The particle acceleration at the shock can
be the origin of radio and X-ray filaments observed near the eastern edge of
W50 nebula surrounding the galactic jet source SS433.Comment: 30 pages, 16 figure
Absolute elastic differential cross sections for electron scattering by C6H5CH3 and C6H5CF3 at 1.5–200 eV: a comparative experimental and theoretical study with C6H6
We present absolute differential cross sections DCS for elastic scattering from two benzene derivatives
C6H5CH3 and C6H5CF3. The crossed-beam method was used in conjunction with the relative flow technique
using helium as the reference gas to obtain absolute values. Measurements were carried out for scattering
angles 15° –130° and impact energies 1.5–200 eV. DCS results for these two molecules were compared to
those of C6H6 from our previous study. We found that 1 these three molecules have DCS with very similar
magnitudes and shapes over the energy range 1.5–200 eV, although DCS for C6H5CF3 increase steeply toward
lower scattering angles due to the dipole moment induced long-range interaction at 1.5 and 4.5 eV, and 2 that
the molecular structure of the benzene ring significantly determines the collision dynamics. From the measured
DCS, elastic integral cross sections have been calculated. Furthermore, by employing a corrected form of the
independent-atom method known as the screen corrected additive rule, DCS calculations have been carried out
without any empirical parameter fittings, i.e., in an ab initio nature. Results show that the calculated DCS are
in excellent agreement with the experimental values at 50, 100, and 200 eV
Extending the linearity range of eddy-current displacement sensor with magnetoplated wire
This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.ArticleIEEE TRANSACTIONS ON MAGNETICS. 43(2): 543-548 (2007)journal articl
Processing and mechanical properties of hollow sphere aluminum foams
Hollow sphere metallic foams are a new class of cellular material that possesses the attractive advantages of uniform cell size distribution and regular cell shape. These result in more predictable physical and mechanical properties than those of cellular materials with a random cell size distribution and irregular cell shapes. In the present study, single aluminum hollow spheres with three kinds of sphere wall thickness as 0.1 mm, 0.3 mm and 0.5 mm were processed by a new pressing method. Hollow sphere aluminum foam samples were prepared by bonding together single hollow spheres with simple cubic packing (SC) and body-centered cubic packing (BCC). Compressive tests were carried out to evaluate the deformation behaviors and mechanical properties of the hollow sphere aluminum foams. Effects of the sphere wall thickness and packing style on the mechanical properties were investigated.<br /
Reduction of eddy current loss in magnetoplated wire
ArticleCOMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING. 28(1):57-66 (2009)journal articl
Reduction of proximity effect in coil using magnetoplated wire
This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.ArticleIEEE TRANSACTIONS ON MAGNETICS. 43(6): 2654-2656 (2007)journal articl
Absolute elastic differential cross sections for electron scattering by C6 H5 CH3 and C6 H5 CF3 at 1.5-200 eV: A comparative experimental and theoretical study with C6 H6
We present absolute differential cross sections (DCS) for elastic scattering from two benzene derivatives C6 H5 CH3 and C6 H5 CF3. The crossed-beam method was used in conjunction with the relative flow technique using helium as the reference gas to obtain absolute values. Measurements were carried out for scattering angles 15°-130° and impact energies 1.5-200 eV. DCS results for these two molecules were compared to those of C6 H6 from our previous study. We found that (1) these three molecules have DCS with very similar magnitudes and shapes over the energy range 1.5-200 eV, although DCS for C6 H5 CF3 increase steeply toward lower scattering angles due to the dipole moment induced long-range interaction at 1.5 and 4.5 eV, and (2) that the molecular structure of the benzene ring significantly determines the collision dynamics. From the measured DCS, elastic integral cross sections have been calculated. Furthermore, by employing a corrected form of the independent-atom method known as the screen corrected additive rule, DCS calculations have been carried out without any empirical parameter fittings, i.e., in an ab initio nature. Results show that the calculated DCS are in excellent agreement with the experimental values at 50, 100, and 200 eV. © 2009 The American Physical Society.F.B. and G.G. were also supported by the Spanish Ministerio de Ciencia e Innovación Project No. FIS0032-00702 and the European Science Foundation EIPAM network and COST Action CM0601.Peer Reviewe
Discovery of possible molecular counterparts to the infrared Double Helix Nebula in the Galactic center
We have discovered two molecular features at radial velocities of -35 km/s
and 0 km/s toward the infrared Double Helix Nebula (DHN) in the Galactic center
with NANTEN2. The two features show good spatial correspondence with the DHN.
We have also found two elongated molecular ridges at these two velocities
distributed vertically to the Galactic plane over 0.8 degree. The two ridges
are linked by broad features in velocity and are likely connected physically
with each other. The ratio between the 12CO J=2-1 and J=1-0 transitions is 0.8
in the ridges which is larger than the average value 0.5 in the foreground gas,
suggesting the two ridges are in the Galactic center. An examination of the K
band extinction reveals a good coincidence with the CO 0 km/s ridge and is
consistent with a distance of 8 +/-2 kpc. We discuss the possibility that the
DHN was created by a magnetic phenomenon incorporating torsional Alfv\'en waves
launched from the circumnuclear disk (Morris, Uchida & Do 2006) and present a
first estimate of the mass and energy involved in the DHN.Comment: 32 pages, 23 figures, Accepted by Ap
Substitution effects in elastic electron collisions with CH3X (X = F, Cl, Br, I) molecules
We report absolute elastic differential, integral, and momentum transfer cross sections for electron interactions with the series of molecules CH3X (X = F, Cl, Br, I). The incident electron energy range is 50–200 eV, while the scattered electron angular range for the differential measurements is 15°–150°. In all cases the absolute scale of the differential cross sections was set using the relative flow method with helium as the reference species. Substitution effects on these cross sections, as we progress along the halomethane series CH3F, CH3Cl, CH3Br, and CH3I, are investigated as a part of this study. In addition, atomic-like behavior in these scattering systems is also considered by comparing these halomethane elastic cross sections to results from other workers for the corresponding noble gases Ne, Ar, Kr, and Xe, respectively. Finally we report results for calculations of elastic differential and integral cross sections for electrons scattering from each of the CH3X species, within an optical potential method and assuming a screened corrected independent atom representation. The level of agreement between these calculations and our measurements was found to be quite remarkable in each case
Substitution effects in elastic electron collisions with CH₃X (X=F, Cl, Br, I) molecules
We report absolute elastic differential, integral, and momentum transfer cross sections for electron interactions with the series of molecules CH₃X (X=F, Cl, Br, I). The incident electron energy range is 50–200 eV, while the scattered electron angular range for the differential measurements is 15°–150°. In all cases the absolute scale of the differential cross sections was set using the relative flow method with helium as the reference species. Substitution effects on these cross sections, as we progress along the halomethane series CH₃F, CH₃Cl, CH3Br, and CH₃I, are investigated as a part of this study. In addition, atomic-like behavior in these scattering systems is also considered by comparing these halomethane elastic cross sections to results from other workers for the corresponding noble gases Ne, Ar, Kr, and Xe, respectively. Finally we report results for calculations of elastic differential and integral cross sections for electrons scattering from each of the CH₃X species, within an optical potential method and assuming a screened corrected independent atom representation. The level of agreement between these calculations and our measurements was found to be quite remarkable in each case.This work was conducted under the support of the Japanese
Ministry of Education, Sport, Culture and Technology
and also by the Ministerio de Educación Ciencia e Innovación
Plan Nacional de Fisica, Project No. FIS2006-
00702, the Consejo de Seguridad Nuclear and the European
Science Foundation COST Action No. CM0601. Additional
support from the Australian Research Council, through its
Centres of Excellence Program, and the Korea Science and
Engineering Foundation Grant No. 2009-0052415 is further
noted. One of us H.K. also acknowledges the Japan Society
for the Promotion of Science JSPS for his fellowships as
grants-in-aid for scientific research and, most recently, to facilitate
his visit to Flinders University and the ANU
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