5,396 research outputs found
Extension Of Bertrand's Theorem And Factorization Of The Radial Schr\"odinger Equation
The Bertrand's theorem is extended, i.e. closed orbits still may exist for
other central potentials than the power law Coulomb potential and isotropic
harmonic oscillator. It is shown that for the combined potential
(), when (and only when) is the Coulomb
potential or isotropic harmonic oscillator, closed orbits still exist for
suitable angular momentum. The correspondence between the closeness of
classical orbits and the existence of raising and lowering operators derived
from the factorization of the radial Schr\"odinger equation is investigated.Comment: 4 pages, 1 figug
Environmental performance of off-site constructed facilities: A critical review
During the recent decades, off-site construction (OSC) has gained a rapid growth worldwide. It has been reported that OSC, as an alternative construction method, has a variety of benefits. However, there is lack of critical review of the building performance (e.g. energy consumption and carbon emissions) of off-site built facilities
Lamellar phase separation and dynamic competition in La0.23Ca0.77MnO3
We report the coexistence of lamellar charge-ordered (CO) and
charge-disordered (CD) domains, and their dynamical behavior, in
La0.23Ca0.77MnO3. Using high resolution transmission electron microscopy (TEM),
we show that below Tcd~170K a CD-monoclinic phase forms within the established
CO-orthorhombic matrix. The CD phase has a sheet-like morphology, perpendicular
to the q vector of the CO superlattice (a axis of the Pnma structure). For
temperatures between 64K and 130K, both the TEM and resistivity experiments
show a dynamic competition between the two phases: at constant T, the CD phase
slowly advances over the CO one. This slow dynamics appears to be linked to the
magnetic transitions occurring in this compound, suggesting important
magnetoelastic effects.Comment: 4 pages, 4 figure
Su(3) Algebraic Structure of the Cuprate Superconductors Model based on the Analogy with Atomic Nuclei
A cuprate superconductor model based on the analogy with atomic nuclei was
shown by Iachello to have an structure. The mean-field approximation
Hamiltonian can be written as a linear function of the generators of
algebra. Using algebraic method, we derive the eigenvalues of the reduced
Hamiltonian beyond the subalgebras and of
algebra. In particular, by considering the coherence between s- and d-wave
pairs as perturbation, the effects of coherent term upon the energy spectrum
are investigated
Optimal moral-hazard-free reinsurance under extended distortion premium principles
We study an optimal reinsurance problem under a diffusion risk model for an
insurer who aims to minimize the probability of lifetime ruin. To rule out
moral hazard issues, we only consider moral-hazard-free reinsurance contracts
by imposing the incentive compatibility constraint on indemnity functions. The
reinsurance premium is calculated under an extended distortion premium
principle, in which the distortion function is not necessarily concave. We
first show that an optimal reinsurance contract always exists and then derive
two sufficient and necessary conditions to characterize it. Due to the presence
of the incentive compatibility constraint and the nonconcavity of the
distortion, the optimal contract is obtained as a solution to a double obstacle
problem. At last, we apply the general result to study three examples and
obtain the optimal contract in (semi)closed form
- …