202,048 research outputs found

### The relativistic continuum Hartree-Bogoliubov description of charge-changing cross section for C,N,O and F isotopes

The ground state properties including radii, density distribution and one
neutron separation energy for C, N, O and F isotopes up to the neutron drip
line are systematically studied by the fully self-consistent microscopic
Relativistic Continuum Hartree-Bogoliubov (RCHB) theory. With the proton
density distribution thus obtained, the charge-changing cross sections for C,
N, O and F isotopes are calculated using the Glauber model. Good agreement with
the data has been achieved. The charge changing cross sections change only
slightly with the neutron number except for proton-rich nuclei. Similar trends
of variations of proton radii and of charge changing cross sections for each
isotope chain is observed which implies that the proton density plays important
role in determining the charge-changing cross sections.Comment: 10 pages, 4 figure

### The surface diffuseness and the spin-orbital splitting in relativistic continuum Hartree-Bogoliubov theory

The Relativistic Continuum Hartree Bogoliubov theory (RCHB), which is the
extension of the Relativistic Mean Field and the Bogoliubov transformation in
the coordinate representation, has been used to study tin isotopes. The pairing
correlation is taken into account by a density-dependent force of zero range.
RCHB is used to describe the even-even tin isotopes all the way from the proton
drip line to the neutron drip line. The contribution of the continuum which is
important for nuclei near the drip-line has been taken into account. The
theoretical $S_{2n}$ as well as the neutron, proton, and matter $rms$ radii are
presented and compared with the experimental values where they exist. The
change of the potential surface with the neutron number has been investigated.
The diffuseness of the potentials in tin isotopes is analyzed through the
spin-orbital splitting in order to provide new way to understand the halo
phenomena in exotic nuclei. The systematic of the isospin and energy dependence
of these results are extracted and analyzed.Comment: 11 figure

### Lorentz Group and Oriented MICZ-Kepler Orbits

The MICZ-Kepler orbits are the non-colliding orbits of the MICZ Kepler
problems (the magnetized versions of the Kepler problem). The oriented
MICZ-Kepler orbits can be parametrized by the canonical angular momentum
$\mathbf L$ and the Lenz vector $\mathbf A$, with the parameter space
consisting of the pairs of 3D vectors $(\mathbf A, \mathbf L)$ with ${\mathbf
L}\cdot {\mathbf L} > (\mathbf L\cdot \mathbf A)^2$. The recent 4D perspective
of the Kepler problem yields a new parametrization, with the parameter space
consisting of the pairs of Minkowski vectors $(a,l)$ with $l\cdot l =-1$,
$a\cdot l =0$, $a_0>0$.
This new parametrization of orbits implies that the MICZ-Kepler orbits of
different magnetic charges are related to each other by symmetries:
\emph{${\mathrm {SO}}^+(1,3)\times {\mathbb R}_+$ acts transitively on both the
set of oriented elliptic MICZ-Kepler orbits and the set of oriented parabolic
MICZ-Kepler orbits}. This action extends to ${\mathrm {O}}^+(1,3)\times
{\mathbb R}_+$, the \emph{structure group} for the rank-two Euclidean Jordan
algebra whose underlying Lorentz space is the Minkowski space.Comment: 7 page

### On pluricanonical maps for threefolds of general type, II

This note mainly studies the generic finiteness of \phi_m of a complex
projective 3-fold of general type. A new result on the classification to
bicanonical pencil for Gorenstein 3-folds is attached in the last section.Comment: 16 pages, Amstex, The final version, Accepted for publication in
Osaka Journal of Mathematic

### The Stability of the Steady State and Bistable Response of a Flexible Rotor Supported on Squeeze Film Dampers

The stability of the steady state response, the bistable response, and the jumping characteristics are analyzed for the case when a system accelerates or decelerates through the bistable region of a flexible rotor-centralized squeeze film damper system. It was found that the system steady state responses have two unstable regions. The larger the unbalance parameter and the smaller the bearing parameter and the external damping ratio, the easier it is for the system to lose stability. The larger the mass ratio and the smaller the stiffness ratio, the lower the threshold rotating speed of instability. The instability of the system steady-state response determined here is due to the system nonsynchronous response in many cases

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