8,690 research outputs found
Interpretation of satellite images of the Republic of Niger
Interpretations of LANDSAT pictures were carried out for an area located in the west of the Niger Republic in the geological, hydrogeological and pedological sectors. Checking of the extent of vegetation and use of the soils and effects of desertification for the purpose of yearly map making was carried out. The proposed control of land use may be optimized by the direct reception of LANDSAT data by the receiving station planned for Ouagadougou. Since that station will not be operating before 1983, the establishment of a mobile reception station in the Republic of Niger to enable the installation of the required control system is advised
Guidance, flight mechanics and trajectory optimization. Volume 12 - Relative motion, guidance equations for terminal rendezvous
Equations of relative motion and guidance for orbital transfer and docking maneuvers in spacecraft rendezvou
Harmonic oscillator well with a screened Coulombic core is quasi-exactly solvable
In the quantization scheme which weakens the hermiticity of a Hamiltonian to
its mere PT invariance the superposition V(x) = x^2+ Ze^2/x of the harmonic and
Coulomb potentials is defined at the purely imaginary effective charges
(Ze^2=if) and regularized by a purely imaginary shift of x. This model is
quasi-exactly solvable: We show that at each excited, (N+1)-st
harmonic-oscillator energy E=2N+3 there exists not only the well known harmonic
oscillator bound state (at the vanishing charge f=0) but also a normalizable
(N+1)-plet of the further elementary Sturmian eigenstates \psi_n(x) at
eigencharges f=f_n > 0, n = 0, 1, ..., N. Beyond the first few smallest
multiplicities N we recommend their perturbative construction.Comment: 13 pages, Latex file, to appear in J. Phys. A: Math. Ge
A survey of possible missions to the periodic comets in the interval 1974 - 2010
Catalogs are developed to survey the mission possibilities for the short period comets. In the first the physical and pertinent orbital characteristics are given for 65 short period comets. The second catalog is one containing the predicted perihelia for each of the 65 comets between 1974 and 2010. Geometry is included to indicate feasibility of Earth-based observation and sighting within 100 days of perihelion. The comets are divided on the basis of size and activity into three groups from the data in the first catalog: primary, secondary and low interest. The perihelia are separated into two groups: satisfactory and not satisfactory on the basis of earth-comet distance
Complex Extension of Quantum Mechanics
It is shown that the standard formulation of quantum mechanics in terms of
Hermitian Hamiltonians is overly restrictive. A consistent physical theory of
quantum mechanics can be built on a complex Hamiltonian that is not Hermitian
but satisfies the less restrictive and more physical condition of space-time
reflection symmetry (PT symmetry). Thus, there are infinitely many new
Hamiltonians that one can construct to explain experimental data. One might
expect that a quantum theory based on a non-Hermitian Hamiltonian would violate
unitarity. However, if PT symmetry is not spontaneously broken, it is possible
to construct a previously unnoticed physical symmetry C of the Hamiltonian.
Using C, an inner product is constructed whose associated norm is positive
definite. This construction is completely general and works for any
PT-symmetric Hamiltonian. Observables exhibit CPT symmetry, and the dynamics is
governed by unitary time evolution. This work is not in conflict with
conventional quantum mechanics but is rather a complex generalisation of it.Comment: 4 Pages, Version to appear in PR
Density distributions of superheavy nuclei
We employed the Skyrme-Hartree-Fock model to investigate the density
distributions and their dependence on nuclear shapes and isospins in the
superheavy mass region. Different Skyrme forces were used for the calculations
with a special comparison to the experimental data in Pb. The
ground-state deformations, nuclear radii, neutron skin thicknesses and
-decay energies were also calculated. Density distributions were
discussed with the calculations of single-particle wavefunctions and shell
fillings. Calculations show that deformations have considerable effects on the
density distributions, with a detailed discussion on the 120 nucleus.
Earlier predictions of remarkably low central density are not supported when
deformation is allowed for.Comment: 7 pages, 10 figure
Deconfined quantum criticality and generalised exclusion statistics in a non-hermitian BCS model
We present a pairing Hamiltonian of the Bardeen-Cooper-Schrieffer form which
exhibits two quantum critical lines of deconfined excitations. This conclusion
is drawn using the exact Bethe ansatz equations of the model which admit a
class of simple, analytic solutions. The deconfined excitations obey
generalised exclusion statistics. A notable property of the Hamiltonian is that
it is non-hermitian. Although it does not have a real spectrum for all choices
of coupling parameters, we provide a rigorous argument to establish that real
spectra occur on the critical lines. The critical lines are found to be
invariant under a renormalisation group map.Comment: 7 pages, 1 figure. Stylistic changes, results unchange
Entangled Quantum State Discrimination using Pseudo-Hermitian System
We demonstrate how to discriminate two non-orthogonal, entangled quantum
state which are slightly different from each other by using pseudo-Hermitian
system. The positive definite metric operator which makes the pseudo-Hermitian
systems fully consistent quantum theory is used for such a state
discrimination. We further show that non-orthogonal states can evolve through a
suitably constructed pseudo-Hermitian Hamiltonian to orthogonal states. Such
evolution ceases at exceptional points of the pseudo-Hermitian system.Comment: Latex, 9 pages, 1 figur
Interactions of Hermitian and non-Hermitian Hamiltonians
The coupling of non-Hermitian PT-symmetric Hamiltonians to standard Hermitian
Hamiltonians, each of which individually has a real energy spectrum, is
explored by means of a number of soluble models. It is found that in all cases
the energy remains real for small values of the coupling constant, but becomes
complex if the coupling becomes stronger than some critical value. For a
quadratic non-Hermitian PT-symmetric Hamiltonian coupled to an arbitrary real
Hermitian PT-symmetric Hamiltonian, the reality of the ground-state energy for
small enough coupling constant is established up to second order in
perturbation theory.Comment: 9 pages, 0 figure
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