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Multi-scale model for coupled piezoelectric-inelastic behavior
Moreno-Navarro, Pablo,Ibrahimbegovic, Adnan,Damjanovic, Dragan Techno-Press 2021 Coupled systems mechanics Vol.10 No.6
In this work, we present the development of a 3D lattice-type model at microscale based upon the Voronoi-cell representation of material microstructure. This model can capture the coupling between mechanic and electric fields with non-linear constitutive behavior for both. More precisely, for electric part we consider the ferroelectric constitutive behavior with the possibility of domain switching polarization, which can be handled in the same fashion as deformation theory of plasticity. For mechanics part, we introduce the constitutive model of plasticity with the Armstrong-Frederick kinematic hardening. This model is used to simulate a complete coupling of the chosen electric and mechanics behavior with a multiscale approach implemented within the same computational architecture.
QUIESCENT COMPACT GALAXIES AT INTERMEDIATE REDSHIFT IN THE COSMOS FIELD. THE NUMBER DENSITY
Damjanov, Ivana,Geller, Margaret J.,Zahid, H. Jabran,Hwang, Ho Seong IOP Publishing 2015 The Astrophysical journal Vol.806 No.2
<P>We investigate the evolution of compact galaxy number density over the redshift range 0.2 < z < 0.8. Our sample consists of galaxies with secure spectroscopic redshifts observed in the COSMOS field. With the large uncertainties, the compact galaxy number density trend with redshift is consistent with a constant value over the interval 0.2 < z < 0.8. Our number density estimates are similar to the estimates at z > 1 for equivalently selected compact samples. Small variations in the abundance of the COSMOS compact sources as a function of redshift correspond to known structures in the field. The constancy of the compact galaxy number density is robust and insensitive to the compactness threshold or the stellar mass range (for M-* > 10(10) M-circle dot). To maintain constant number density any size growth of high-redshift compact systems with decreasing redshift must be balanced by a formation of quiescent compact systems at z < 1.</P>
hCOSMOS: A Dense Spectroscopic Survey of <i>r</i> ≤ 21.3 Galaxies in the COSMOS field
Damjanov, Ivana,Zahid, H. Jabran,Geller, Margaret J.,Fabricant, Daniel G.,Hwang, Ho Seong American Astronomical Society 2018 The Astrophysical journal Supplement series Vol.234 No.2
<P>We describe the hCOSMOS redshift survey of the COSMOS field conducted with the Hectospec spectrograph on the MMT. In the central 1. deg(2), the hCOS20.6 subset of the survey is > 90% complete to a limiting magnitude r = 20.6. The hCOSMOS survey includes 1701 new redshifts in the COSMOS field. We also use the total of 4362 new and remeasured objects to derive the age-sensitive D(n)4000 index over the entire redshift interval 0.001 less than or similar to z less than or similar to 0.6. For 85% of the quiescent galaxies in hCOS20.6, we measure the central line-of-sight velocity dispersion. To explore potential uses of this survey, we combine previously measured galaxy sizes, profiles, and stellar masses with the spectroscopy. The comparison reveals the known relations among structural, kinematic, and stellar population properties. We also compare redshift and Dn4000 distributions of hCOS20.6 galaxies with SHELS; a complete spectroscopic survey of 4 deg(2) observed to the same depth. The redshift distributions in the two fields are very different, but the Dn4000 distribution is remarkably similar. The relation between velocity dispersion and stellar mass for massive hCOS20.6 galaxies is consistent with the local relation from the Sloan Digital Sky Survey. Using measured velocity dispersions, we test a photometric proxy calibrated to galaxies in the local universe. The systematic differences between the measured and photometric proxy velocity dispersions are correlated with galaxy dynamical and stellar population properties highlighting the importance of direct spectroscopic measurements.</P>
THE STELLAR MASS FUNDAMENTAL PLANE AND COMPACT QUIESCENT GALAXIES AT<i>z</i>< 0.6
Zahid, H. Jabran,Damjanov, Ivana,Geller, Margaret J.,Hwang, Ho Seong,Fabricant, Daniel G. American Astronomical Society 2016 The Astrophysical Journal Vol.821 No.2
<P>We examine the evolution of the relation between stellar mass surface density, velocity dispersion, and half-light radius-the stellar mass fundamental plane (MFP)-for quiescent galaxies at z < 0.6. We measure the local relation from galaxies in the Sloan Digital Sky Survey and the intermediate redshift relation from similar to 500 quiescent galaxies with stellar masses 10 less than or similar to log(M*/M-circle dot) less than or similar to 11.5. Nearly half of the quiescent galaxies in our intermediate redshift sample are compact. After accounting for important selection and systematic effects, the velocity dispersion distribution of galaxies at intermediate redshifts is similar to that of galaxies in the local universe. Galaxies at z < 0.6 appear to be smaller (less than or similar to 0.1 dex) than galaxies in the local sample. The orientation of the stellar MFP is independent of redshift for massive quiescent galaxies at z < 0.6 and the zero-point evolves by similar to 0.04 dex. Compact quiescent galaxies fall on the same relation as the extended objects. We confirm that compact quiescent galaxies are the tail of the size and mass distribution of the normal quiescent galaxy population.</P>