5,350 research outputs found
Mission analysis data for inclined geosynchronous orbits, part 1
Data needed for preliminary design of inclined geosynchronous missions are provided. The inertial and Earth fixed coordinate systems are described, as well as orbit parameters and elements. The complete family of geosynchronous orbits is discussed. It is shown that circular inclined geosynchronous orbits comprise only one set in this family. The major orbit perturbation and their separate effects on the geosynchronous orbit are discussed. Detailed information on the orbit perturbation of inclined circular geosynchronous orbits is given, with emphasis on time history data of certain orbital elements. Orbit maintenance delta velocity (V) requirements to counteract the major orbit perturbations are determined in order to provide order of magnitude estimates and to show the effects of orbit inclination on delta V. Some of the considerations in mission design for a multisatellite system, such as a halo orbit constellation, are discussed
The method of averages applied to the KS differential equations
A new approach for the solution of artificial satellite trajectory problems is proposed. The basic idea is to apply an analytical solution method (the method of averages) to an appropriate formulation of the orbital mechanics equations of motion (the KS-element differential equations). The result is a set of transformed equations of motion that are more amenable to numerical solution
Josephson effect in point contacts between ''f-wave'' superconductors
A stationary Josephson effect in point contacts between triplet
superconductors is analyzed theoretically for most probable models of the order
parameter in UPt_{3} and Sr_{2}RuO_{4}. The consequence of misorientation of
crystals in superconducting banks on this effect is considered. We show that
different models for the order parameter lead to quite different current-phase
dependences. For certain angles of misorientation a boundary between
superconductors can generate the parallel to surface spontaneous current. In a
number of cases the state with a zero Josephson current and minimum of the free
energy corresponds to a spontaneous phase difference. This phase difference
depends on the misorientation angle and may possess any value. We conclude that
experimental investigations of the current-phase dependences of small junctions
can be used for determination of the order parameter symmetry in the mentioned
above superconductors.Comment: 11 pages, 8 figure
Quantum response of dephasing open systems
We develop a theory of adiabatic response for open systems governed by
Lindblad evolutions. The theory determines the dependence of the response
coefficients on the dephasing rates and allows for residual dissipation even
when the ground state is protected by a spectral gap. We give quantum response
a geometric interpretation in terms of Hilbert space projections: For a two
level system and, more generally, for systems with suitable functional form of
the dephasing, the dissipative and non-dissipative parts of the response are
linked to a metric and to a symplectic form. The metric is the Fubini-Study
metric and the symplectic form is the adiabatic curvature. When the metric and
symplectic structures are compatible the non-dissipative part of the inverse
matrix of response coefficients turns out to be immune to dephasing. We give
three examples of physical systems whose quantum states induce compatible
metric and symplectic structures on control space: The qubit, coherent states
and a model of the integer quantum Hall effect.Comment: Article rewritten, two appendices added. 16 pages, 2 figure
Atrial Fibrillation-Induced Cardiac Shock: First Manifestation of a Congenitally Corrected Transposition of the Great Arteries in a 45-Year-Old Man
Background. The congenitally corrected transposition of the great arteries (L-TGA) is a very rare congenital heart defect, which often remains undetected for several decades of life. Case Presentation. We report on a 45-year-old man without prior history of heart disease, presenting with cardiac shock related to a first episode of tachycardic atrial fibrillation. The diagnostic work-up identified a L-TGA as the underlying cause for acute heart failure. Discussion. L-TGA is a very rare congenital heart defect, which is characterized by an atrioventricular as well as a ventriculoarterial discordance. By this means, the physiological sequence of pulmonary and systemic circulation is still maintained. On the basis of an ongoing strain of the right ventricle, which has to carry the burden of the systemic blood pressure, after more than four decades without symptoms, acute heart failure was triggered by a tachycardic atrial fibrillation
A constant of quantum motion in two dimensions in crossed magnetic and electric fields
We consider the quantum dynamics of a single particle in the plane under the
influence of a constant perpendicular magnetic and a crossed electric potential
field. For a class of smooth and small potentials we construct a non-trivial
invariant of motion. Do to so we proof that the Hamiltonian is unitarily
equivalent to an effective Hamiltonian which commutes with the observable of
kinetic energy.Comment: 18 pages, 2 figures; the title was changed and several typos
corrected; to appear in J. Phys. A: Math. Theor. 43 (2010
Nonthermal fragmentation of C60
A theoretical study of the subpicosecond fragmentation of C60 clusters in
response to ultrafast laser pulses is presented. We simulate the laser
excitation and the consequent nonequilibrium relaxation dynamics of the
electronic and nuclear degrees of freedom. The first stages of the
nonequilibrium dynamics are dominated by a coherent breathing mode followed by
the cold ejection of single C atoms, in contrast to the dimer emission which
characterizes the thermal relaxation. We also determine the nonequilibrium
damage thresholds as a function of the pulse duration.Comment: 5 pages, 4 figures, submitted to Chem. Phys. Let
Predicting general criminal recidivism in mentally disordered offenders using a random forest approach
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