228,270 research outputs found
Convergence of the largest eigenvalue of normalized sample covariance matrices when p and n both tend to infinity with their ratio converging to zero
Let
where 's are independent and identically distributed (i.i.d.) random
variables with and . It is showed
that the largest eigenvalue of the random matrix
tends to 1 almost surely as with
.Comment: Published in at http://dx.doi.org/10.3150/11-BEJ381 the Bernoulli
(http://isi.cbs.nl/bernoulli/) by the International Statistical
Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm
Analysis of elastically tailored viscoelastic damping member
For more than two decades, viscoelastic materials have been commonly used as a passive damping source in a variety of structures because of their high material loss factors. In most of the applications, viscoelastic materials are used either in series with or parallel to the structural load path. The latter is also known as the constrained-layer damping treatment. The advantage of the constrained-layer damping treatment is that it can be incorporated without loss in structural integrity, namely, stiffness and strength. However, the disadvantages are that: (1) it is not the most effective use of the viscoelastic material when compared with the series-type application, and (2) weight penalty from the stiff constraining layer requirement can be excessive. To overcome the disadvantages of the constrained-layer damping treatment, a new approach for using viscoelastic material in axial-type structural components, e.g., truss members, was studied in this investigation
Temperature variation of the resistivity of metallic strain gauge materials Final report
Temperature effects on electrical resistivity of metallic strain gage material
Behavior of the collective rotor in wobbling motion
The behavior of the collective rotor in wobbling motion is investigated
within the particle-rotor model for the nucleus Pr by transforming the
wave functions from the -representation to the -representation. After
reproducing the experimental energy spectra and wobbling frequencies, the
evolution of the wobbling mode in Pr, from transverse at low spins to
longitudinal at high spins, is illustrated by the distributions of the total
angular momentum in the intrinsic reference frame (azimuthal plot). Finally,
the coupling schemes of the angular momenta of the rotor and the high-
particle for transverse and longitudinal wobbling are obtained from the
analysis of the probability distributions of the rotor angular momentum
(-plots) and their projections onto the three principal axes (-plots).Comment: 21 pages, 9 page
Effective field theory for triaxially deformed nuclei
Effective field theory (EFT) is generalized to investigate the rotational
motion of triaxially deformed even-even nuclei. A Hamiltonian, called the
triaxial rotor model (TRM), is obtained up to next-to-leading order (NLO)
within the EFT formalism. Its applicability is examined by comparing with a
five-dimensional collective Hamiltonian (5DCH) for the description of the
energy spectra of the ground state and band in Ru isotopes. It is
found that by taking into account the NLO corrections, the ground state band in
the whole spin region and the band in the low spin region are well
described. The results presented here indicate that it should be possible to
further generalize the EFT to triaxial nuclei with odd mass number.Comment: 21 pages, 9 figure
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Superconducting Bearing Design for Outer Rotor Flywheel Using Lumped Parameter Techniques
This paper describes the application of lumped parameter modeling techniques to designing high temperature superconducting bearings for outer-rotor flywheel energy storage systems. The lumped parameter models decrease computational time by 99% compared to Finite Element Analysis (FEM) without compromising fidelity needed to capture the non-linear and hysteretic force-displacement behavior between a levitated permanent magnet and bulk superconductor. The techniques formulated can be used to quickly evaluate lifting capacity and translational stiffness for a superconducting bearing design. The validity of the modeling approach has been verified by comparing results from FEM studies and experimental tests.Center for Electromechanic
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