4,298 research outputs found
Relation between the autocorrelation and Wigner functions
We show a simple mechanism to measure the Wigner function of a harmonic
oscillator. For this system we also show that autocorrelation and Wigner
functions are equivalent.Comment: Modified title and slightly modified version from the one publishe
Fracture toughness testing data: A technology survey and bibliography
Announced survey includes reports covering fracture toughness testing for various structural materials including information on plane strain and developing areas of mixed mode and plane strain test conditions. Bibliography references cite work and conclusions in fracture toughness testing and application of fracture toughness test data, and in fracture mechanics analysis
Propagation and perfect transmission in three-waveguide axially varying couplers
We study a class of three-waveguide axially varying structures whose dynamics
are described by the su(3) algebra. Their analytic propagator can be found
based on the corresponding Lie group generators. In particular, we show that
the field propagator corresponding to three-waveguide structures that have
arbitrarily varying coupling coefficients and identical refractive indices is
associated with the orbital angular momentum algebra. The conditions necessary
to achieve perfect transmission from the first to the last waveguide element
are obtained and particular cases are elucidated analytically.Comment: 5 pages, 4 figure
Life prediction of materials exposed to monotonic and cyclic loading: A technology survey and bibliography
Announced survey directs attention toward low cycle fatigue and thermal fatigue experienced at elevated temperatures equivalent to those found in hot end of gas turbine engine. Majority of bibliographic references are on life prediction for materials exposed to monotonic and cyclic loading in high temperature environments
A squeeze-like operator approach to position-dependent mass in quantum mechanics
We provide a squeeze-like transformation that allows one to remove a position
dependent mass from the Hamiltonian. Methods to solve the Schr\"{o}dinger
equation may then be applied to find the respective eigenvalues and
eigenfunctions. As an example, we consider a position-dependent-mass that leads
to the integrable Morse potential and therefore to well-known solutions
Fracture toughness testing data. A bibliography
This bibliography is comprised of approximately 800 reference citations related to the mechanics of failure in aerospace structures. Most of the references are for documents that include fracture toughness testing data and its application or documents on the availability and usefulness of fracture mechanics analysis methodology. The bibliography represents a search of the literature published in the period April 1962 through April 1974 and is largely limited to documents published in the United States
Temperature dependence of the volume and surface contributions to the nuclear symmetry energy within the coherent density fluctuation model
The temperature dependence of the volume and surface components of the
nuclear symmetry energy (NSE) and their ratio is investigated in the framework
of the local density approximation (LDA). The results of these quantities for
finite nuclei are obtained within the coherent density fluctuation model
(CDFM). The CDFM weight function is obtained using the temperature-dependent
proton and neutron densities calculated through the HFBTHO code that solves the
nuclear Skyrme-Hartree-Fock-Bogoliubov problem by using the cylindrical
transformed deformed harmonic-oscillator basis. We present and discuss the
values of the volume and surface contributions to the NSE and their ratio
obtained for the Ni, Sn, and Pb isotopic chains around double-magic Ni,
Sn, and Pb nuclei. The results for the -dependence of the
considered quantities are compared with estimations made previously for zero
temperature showing the behavior of the NSE components and their ratio, as well
as with the available experimental data. The sensitivity of the results on
various forms of the density dependence of the symmetry energy is studied. We
confirm the existence of `kinks' of these quantities as functions of the mass
number at MeV for the double closed-shell nuclei Ni and Sn
and the lack of `kinks' for the Pb isotopes, as well as the disappearance of
these kinks as the temperature increases.Comment: 14 pages, 12 figures, 1 table, accepted for publication in Physical
Review
Life prediction of materials exposed to monotonic and cyclic loading: Bibliography
This bibliography is comprised of approximately 1200 reference citations related to the mechanics of failure in aerospace structures. Most of the references are for information on life prediction for materials exposed to monotonic and cyclic loading in elevated temperature environments such as that in the hot end of a gas turbine engine. Additional citations listed are for documents on the thermal and mechanical effects on solar cells in the cryogenic vacuum environment; radiation effects on high temperature mechanical properties; and high cycle fatigue technology as applicable to gas turbine engine bearings. The bibliography represents a search of the literature published in the period April 1962 through April 1974 and is largely limited to documents published in the United States. It is a companion volume to NASA CR-134750, Life Prediction of Materials Exposed to Monotonic and cyclic Loading - A Technology Survey
Ground-state properties and symmetry energy of neutron-rich and neutron-deficient Mg isotopes
A comprehensive study of various ground-state properties of neutron-rich and
neutron-deficient Mg isotopes with =20-36 is performed in the framework of
the self-consistent deformed Skyrme-Hartree-Fock plus BCS method. The
correlation between the skin thickness and the characteristics related with the
density dependence of the nuclear symmetry energy is investigated for this
isotopic chain following the theoretical approach based on the coherent density
fluctuation model and using the Brueckner energy-density functional. The
results of the calculations show that the behavior of the nuclear charge radii
and the nuclear symmetry energy in the Mg isotopic chain is closely related to
the nuclear deformation. We also study, within our theoretical scheme, the
emergence of an "island of inversion" at neutron-rich Mg nucleus, that
was recently proposed from the analyses of spectroscopic measurements of
Mg low-lying energy spectrum and the charge rms radii of all magnesium
isotopes in the shell.Comment: 13 pages, 13 figures, to be published in Physical Review
Ermakov-Lewis symmetry in photonic lattices
We present a class of waveguide arrays that is the classical analog of a
quantum harmonic oscillator where the mass and frequency depend on the
propagation distance. In these photonic lattices refractive indices and second
neighbor couplings define the mass and frequency of the analog quantum
oscillator, while first neighbor couplings are a free parameter to adjust the
model. The quantum model conserves the Ermakov-Lewis invariant, thus the
photonic crystal also posses this symmetry.Comment: 8 pages, 3 figure
- …