scholarly journals Radio broad-band visualization of global three-dimensional magnetohydrodynamical simulations of spiral galaxies – II. Faraday depolarization from 100 MHz to 10 GHz

2018 ◽  
Vol 482 (3) ◽  
pp. 3394-3402 ◽  
Author(s):  
M Machida ◽  
T Akahori ◽  
K E Nakamura ◽  
H Nakanishi ◽  
M Haverkorn
Keyword(s):  
Spiral Galaxies ◽  
Broad Band ◽  
Three Dimensional

scholarly journals Differences in Mass Distribution for Field and Cluster Spiral Galaxies

1987 ◽  
Vol 117 ◽  
pp. 66-66 ◽  
Author(s):  
David Burstein ◽  
Vera C. Rubin
Keyword(s):  
Mass Distribution ◽  
Classification Scheme ◽  
Spiral Galaxies ◽  
Three Dimensional ◽  
Rotation Curves ◽  
Mass Distributions ◽  
Distribution Form ◽  
Simple Classification ◽  
Observational Fact

Our group has now obtained rotation curves for 80 spiral galaxies, Hubble types Sa through Sd. As described in Rubin et al. (Ap. J. 289, 81; 1985), the forms of these rotation curves are similar for all Hubble types. Given this observational fact, we have chosen to analyze the mass distributions for these galaxies under the assumption that the mass distributions for all spirals can be described by the same three-dimensional form, here taken to be spherical for simplicity. The mass distribution forms for 71 of these galaxies can be placed into a simple classification scheme based on the curvature of mass distribution form in a log(radius) - log (integral mass) diagram. The three most common mass forms among this continuum are termed Types I, II and III, the forms of which are displayed below (see also the discussion by Rubin elsewhere in this Symposium).

A dynamical study of three-dimensional spiral galaxies

2001 ◽  
Vol 25 (2) ◽  
pp. 159-169
Author(s):  
Luo Xin-Lian ◽  
Long Min ◽  
Peng Qiu-he ◽  
Chou Chi-kang
Keyword(s):  
Spiral Galaxies ◽  
Three Dimensional ◽  
Dynamical Study

scholarly journals Environmental Effects on the Properties of Spiral Galaxies: Isolated Pairs of Spirals

1996 ◽  
Vol 171 ◽  
pp. 410-410
Author(s):  
I. Márquez
Keyword(s):  
Fourier Analysis ◽  
Size Distribution ◽  
Environmental Effects ◽  
Spiral Galaxies ◽  
Narrow Band ◽  
Broad Band ◽  
Hii Regions ◽  
Total Emission ◽  
Rotation Curves ◽  
Simulated Images

We characterized isolated spiral galaxies as a reference for the properties of interacting ones: we selected all the spirals in CfA catalog with mB ≤ 13.0,δ ≥ 0, a≤ 4′ and 73° > i > 32°. The isolated ones were those having no companions in ΔD≤0.5Mpc and ΔV≤500 km/s and no satellites galaxies in their neighborhood (from Nilson catalog and Palomar charts). To select the isolated pairs of spirals we used Karachentsev's catalog applying similar conditions for mB, δ, a, i and the same isolation criteria. We used broad band CCD images (Johnson B,V e I), narrow band CCD images (Hα) and long slit spectra in Ha region. The BVI images analysis consisted on applying sharp-divided methods, obtaining simulated images (from bulge/disk decomposition and galaxy orientation in the sky) and Fourier analysis. From Hα images we determined total emission, size, distribution and flux of HII regions. We also obtained the rotation curves.

A broad-band three-dimensional isotropic left-handed metamaterial

2009 ◽  
Vol 42 (15) ◽  
pp. 155413 ◽  
Author(s):  
Jia Fu Wang ◽  
Shao Bo Qu ◽  
Zhuo Xu ◽  
Zhen Tang Fu ◽  
Hua Ma ◽  
...  
Keyword(s):  
Broad Band ◽  
Three Dimensional ◽  
Left Handed

scholarly journals Dependence of Enstrophy Transport and Mixed Mass on Dimensionality and Initial Conditions in the Richtmyer–Meshkov Instability Induced Flows1

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Ye Zhou ◽  
Michael Groom ◽  
Ben Thornber
Keyword(s):  
Inertial Confinement Fusion ◽  
Initial Conditions ◽  
Broad Band ◽  
Initial Perturbation ◽  
Density Ratio ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Late Time ◽  
Production Term

Abstract This paper presents a comparative study of the enstrophy budget and mixed mass between two- and three-dimensional flows induced by Richtmyer–Meshkov instability (RMI). Specifically, the individual contributions to the enstrophy budget due to the production from baroclinicity and from vortex stretching (which vanishes in two-dimensional (2D) flow) are delineated. This is enabled by a set of two- and three-dimensional computations at Atwood 0.5 having both narrow- and broad-band perturbations. A further three-dimensional (3D) computation is conducted at Atwood 0.9 using an identical narrowband perturbation to the Atwood 0.5 case to examine the sensitivity to density ratio. The mixed mass is also considered with the goal to obtain insight on how faithfully a simplified calculation performed in two dimensions can capture the mixed mass for an inertial confinement fusion (ICF) or other practical application. It is shown that the late time power law decay of variable density enstrophy is substantially different in two and three dimensions for the narrowband initial perturbation. The baroclinic production term is negligible in three dimensions (aside from the initial shock interaction), as vortex stretching is larger by two orders of magnitude. The lack of vortex stretching considerably reduces the decay rate in both narrowband and broadband perturbations in two dimensions. In terms of mixed mass, the lack of vortex stretching reduces the mixed mass in two dimensions compared to three in all cases. In the broadband cases, the spectral bandwidth in the 2D case is wider; hence, there is a longer time period of sustained linear growth which reduces the normalized mixed mass further.

scholarly journals The Ultra-low Frequency and Broad Band Gaps Characteristics of Multilayer Composite Cylindrical Three-dimensional pentamode metamaterials

2021 ◽  
Author(s):  
Chengxin Cai ◽  
Xue Wang ◽  
Qifu Wang ◽  
Mingxing Li ◽  
Guangchen He ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Broad Band ◽  
Three Dimensional ◽  
Engineering Application ◽  
Low Frequency ◽  
Single Mode ◽  
Band Gaps ◽  
Multilayer Composite ◽  
Lattice Constants ◽  
Mode Area

Abstract For three-dimensional pentamode metamaterials, it is of great significance to realize underwater ultra-low frequency acoustic wave control. Therefore, two types multilayer composite cylindrical three-dimensional pentamode metamaterials with ultra-low frequency and broad band gaps are proposed in this paper. By using pentamode metamaterials with lattice constants on the order of centimeters, the phononic band gaps below 60 Hz and the single-mode area below 30Hz can be obtained. Compared with asymmetrical double-cone locally resonant pentamode metamaterials, the lower edge frequency, relative bandwidth and figure of merit of the first phononic band gap can be reduced by up to 61.4%, 10.3% and 40.6%, respectively. It will provide reference and guidance for the engineering application of pentamode metamaterials in controlling the ultra-low frequency broadband acoustic waves, vibration and noise reduction.

On the modulating effect of three-dimensional instabilities in open cavity flows

2014 ◽  
Vol 759 ◽  
pp. 546-578 ◽  
Author(s):  
J. Basley ◽  
L. R. Pastur ◽  
F. Lusseyran ◽  
J. Soria ◽  
N. Delprat
Keyword(s):  
Shear Layer ◽  
Travelling Waves ◽  
Broad Band ◽  
Three Dimensional ◽  
High Energy ◽  
Open Cavity ◽  
Coupling Mechanism ◽  
Cavity Flows ◽  
Low Frequencies ◽  
Sustained Oscillations

AbstractOpen cavity flows are known to select and enhance locked-on modes or tones. High-energy self-sustained oscillations arise within the shear layer, impinging onto the trailing edge of the cavity. These self-sustained oscillations are subject to amplitude modulations (AMs) at multiple low frequencies. However, only a few studies have addressed the identification of the lowest modulating frequencies. The present work brings to light salient AMs of the shear layer waves and identifies their source as three-dimensional dynamics existing inside the cavity. Indeed, the recirculating inner flow gives rise to centrifugal instabilities, which entail broad-band frequencies down two orders of magnitude lower than those of the self-sustained oscillations. Using time-resolved PIV (TRPIV) in two planes, the nonlinearly saturated dynamics is analysed in both space and time by means of proper orthogonal decomposition, global Fourier decomposition and Hilbert–Huang transforms. The inner flow can be decomposed as three-dimensional waves carried by the main recirculation. Bicoherence distributions are computed to highlight the nonlinear interactions between these spanwise-travelling waves inside the cavity and the locked-on modes. The modulated envelope of the shear layer oscillations is extracted and investigated with regards to the inner-flow dynamics. Strong cross-correlations, in time rather than in space, reveal a global coupling mechanism, possibly related to the beating of the spanwise-travelling waves.

Constructing Repairable Meta-Structures of Ultra-Broad-Band Electromagnetic Absorption from Three-Dimensional Printed Patterned Shells

2017 ◽  
Vol 9 (49) ◽  
pp. 43179-43187 ◽  
Author(s):  
Wei-Li Song ◽  
Zhili Zhou ◽  
Li-Chen Wang ◽  
Xiao-Dong Cheng ◽  
Mingji Chen ◽  
...  
Keyword(s):  
Broad Band ◽  
Three Dimensional ◽  
Electromagnetic Absorption

scholarly journals Multiband Photometry of NGC 7479 and NGC 7606

1996 ◽  
Vol 157 ◽  
pp. 123-125
Author(s):  
A. M. Varela ◽  
J. A. L. Aguerri ◽  
M. Prieto ◽  
C. Muñoz-Tuñón
Keyword(s):  
Spiral Galaxies ◽  
Three Dimensional ◽  
Surface Photometry ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Isaac Newton ◽  
La Palma ◽  
Radial Profiles ◽  
Isaac Newton Telescope ◽  
Barred Spiral Galaxies

We present surface photometry in U BV RI passbands of the barred spiral galaxies NGC 7479 and NGC 7606, for which observations were obtained at the Cassegrain focus of the 2.5-m Isaac Newton Telescope at La Palma. Data are presented in the form of images and mean radial profiles from azimuthal fits of ellipses, giving the luminosity, ellipticities and position angles of the isophotes as functions of the galactocentric radii. Images in I-band are shown in Figure 1 of NGC 7479 (left) and NGC 7606 (right). These belong to a sample of galaxies with moderate circumnuclear starbursts. We are analyzing their structure to study the effects of departures from an axisymmetric potential for the dynamics of a galaxy. One objective of this study is to make a three-dimensional model of the bar and bulge using the method of photometric inversion. The sample consists of 27 spiral galaxies with and without a bar.

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