35,177 research outputs found
Investigation of an axial-excursion transducer for squeeze-film bearings
Resonant frequencies and characteristic bearing cone motion of axial-excursion transducer for squeeze-film gas bearing - drive voltage, preload, bearing mass, and mounting ring effect
Effects of neutrino mass hierarchies on dynamical dark energy models
We investigate how three different possibilities of neutrino mass
hierarchies, namely normal, inverted, and degenerate, can affect the
observational constraints on three well known dynamical dark energy models,
namely the Chevallier-Polarski-Linder, logarithmic, and the
Jassal-Bagla-Padmanabhan parametrizations. In order to impose the observational
constraints on the models, we performed a robust analysis using Planck 2015
temperature and polarization data, Supernovae type Ia from Joint Light curve
analysis, baryon acoustic oscillations distance measurements, redshift space
distortion characterized by data, weak gravitational lensing
data from Canada-France-Hawaii Telescope Lensing Survey, and cosmic
chronometers data plus the local value of the Hubble parameter. We find that
different neutrino mass hierarchies return similar fit on almost all model
parameters and mildly change the dynamical dark energy properties.Comment: 10 pages, 5 captioned figures, 4 tables; Published version in Phys.
Rev.
Microscopic origin of the next generation fractional quantum Hall effect
Most of the fractions observed to date belong to the sequences and , and integers, understood as the familiar
{\em integral} quantum Hall effect of composite fermions. These sequences fail
to accommodate, however, many fractions such as and 5/13, discovered
recently in ultra-high mobility samples at very low temperatures. We show that
these "next generation" fractional quantum Hall states are accurately described
as the {\em fractional} quantum Hall effect of composite fermions
Analysis, design, and prototype development of squeeze-film bearings for AB-5 gyro Final report phase 2, design, fabrication and evaluation of prototypes
Squeeze-film bearing transducers with piezoceramic cylinders for AB-5 gyro - design, fabrication, and testing of cylindrical journal and annular bearing prototype
Reactively sputtered RuO2 diffusion barriers
The thermal stability of reactively sputtered RuO2 films is investigated from the point of view of their application as diffusion barriers in silicon contact metallizations with an Al overlayer. Backscattering spectra of Si/RuO2/Al samples and electrical measurements on shallow junction diodes with Si/TiSi2.3/RuO2/Al contacts both show that RuO2 films are effective diffusion barriers between Al and Si for 30-min annealing at temperatures as high as 600°C
Unique Thermal Properties of Clothing Materials.
Cloth wearing seems so natural that everyone is self-deemed knowledgeable and has some expert opinions about it. However, to clearly explain the physics involved, and hence to make predictions for clothing design or selection, it turns out to be quite challenging even for experts. Cloth is a multiphased, porous, and anisotropic material system and usually in multilayers. The human body acts as an internal heat source in a clothing situation, thus forming a temperature gradient between body and ambient. But unlike ordinary engineering heat transfer problems, the sign of this gradient often changes as the ambient temperature varies. The human body also perspires and the sweat evaporates, an effective body cooling process via phase change. To bring all the variables into analysis quickly escalates into a formidable task. This work attempts to unravel the problem from a physics perspective, focusing on a few rarely noticed yet critically important mechanisms involved so as to offer a clearer and more accurate depiction of the principles in clothing thermal comfort
Listening to the sound of dark sector interactions with gravitational wave standard sirens
We consider two stable Interacting Dark Matter -- Dark Energy models and
confront them against current Cosmic Microwave Background data from the
\textit{Planck} satellite. We then generate luminosity distance measurements
from mock Gravitational Wave events matching the expected
sensitivity of the proposed Einstein Telescope. We use these to forecast how
the addition of Gravitational Wave standard sirens data can improve current
limits on the Dark Matter -- Dark Energy coupling strength (). We find
that the addition of Gravitational Waves data can reduce the current
uncertainty by a factor of . Moreover, if the underlying cosmological model
truly features Dark Matter -- Dark Energy interactions with a value of
within the currently allowed upper limit, the addition of
Gravitational Wave data would help disentangle such an interaction from the
standard case of no interaction at a significance of more than .Comment: 16 pages, 3 tables, 4 figures; version published in JCA
Electron-phonon interaction in quantum-dot/quantum-well semiconductor heterostructures
Polar optical phonons are studied in the framework of the dielectric
continuum approach for a prototypical quantum-dot/quantum-well (QD/QW)
heterostructure, including the derivation of the electron-phonon interaction
Hamiltonian and a discussion of the effects of this interaction on the
electronic energy levels. The particular example of the CdS/HgS QD/QW is
addressed and the system is modelled according to the spherical geometry,
considering a core sphere of material "1" surrounded by a spherically
concentric layer of material "2", while the whole structure is embedded in a
host matrix assumed as an infinite dielectric medium. The strength of the
electron-LO phonon coupling is discussed in details and the polaronic
corrections to both ground state and excited state electron energy levels are
calculated. Interesting results concerning the dependence of polaronic
corrections with the QD/QW structure size are analyzed.Comment: 8 pages, 5 figure
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