19,110 research outputs found
Synthesis of calculational methods for the design and analysis of radiation shields for nuclear rocket systems. Volume 5 - TIC-TOC-TOE, a FORTRAN program for the temperature in the coolant tank and other calculations and for the thermal neutron originating energy Final progress report
TIC-TOC-TOE computer program for radiation shielding design and analysis in nuclear rocket system
Discrete Reductive Perturbation Technique
We expand a partial difference equation (PE) on multiple lattices and
obtain the PE which governs its far field behaviour. The
perturbative--reductive approach is here performed on well known nonlinear
PEs, both integrable and non integrable. We study the cases of the
lattice modified Korteweg--de Vries (mKdV) equation, the Hietarinta equation,
the lattice Volterra--Kac--Van Moerbeke (VKVM) equation and a non integrable
lattice KdV equation. Such reductions allow us to obtain many new PEs
of the nonlinear Schr\"odinger (NLS) type.Comment: 18 pages, 1 figure. submitted to Journal of Mathematical Physic
Model for Cumulative Solar Heavy Ion Energy and Linear Energy Transfer Spectra
A probabilistic model of cumulative solar heavy ion energy and LET spectra is developed for spacecraft design applications. Spectra are given as a function of confidence level, mission time period during solar maximum and shielding thickness. It is shown that long-term solar heavy ion fluxes exceed galactic cosmic ray fluxes during solar maximum for shielding levels of interest. Cumulative solar heavy ion fluences should therefore be accounted for in single event effects rate calculations and in the planning of space missions
Fuzzy Topology, Quantization and Gauge Invariance
Dodson-Zeeman fuzzy topology considered as the possible mathematical
framework of quantum geometric formalism. In such formalism the states of
massive particle m correspond to elements of fuzzy manifold called fuzzy
points. Due to their weak (partial) ordering, m space coordinate x acquires
principal uncertainty dx. It's shown that m evolution with minimal number of
additional assumptions obeys to schroedinger and dirac formalisms in
norelativistic and relativistic cases correspondingly. It's argued that
particle's interactions on such fuzzy manifold should be gauge invariant.Comment: 12 pages, Talk given on 'Geometry and Field Theory' conference,
Porto, July 2012. To be published in Int. J. Theor. Phys. (2015
A periodically active pulsar giving insight into magnetospheric physics
PSR B1931+24 (J1933+2421) behaves as an ordinary isolated radio pulsar during
active phases that are 5-10 days long. However, the radio emission switches off
in less than 10 seconds and remains undetectable for the next 25-35 days, then
it switches on again. This pattern repeats quasi-periodically. The origin of
this behaviour is unclear. Even more remarkably, the pulsar rotation slows down
50% faster when it is on than when it is off. This indicates a massive increase
in magnetospheric currents when the pulsar switches on, proving that pulsar
wind plays a substantial role in pulsar spin-down. This allows us, for the
first time, to estimate the currents in a pulsar magnetospheric during the
occurrence of radio emission.Comment: 12 pages, 2 figure
A New Symmetric Expression of Weyl Ordering
For the creation operator \adag and the annihilation operator of a
harmonic oscillator, we consider Weyl ordering expression of (\adag a)^n and
obtain a new symmetric expression of Weyl ordering w.r.t. \adag a \equiv N
and a\adag =N+1 where is the number operator. Moreover, we interpret
intertwining formulas of various orderings in view of the difference theory.
Then we find that the noncommutative parameter corresponds to the increment of
the difference operator w.r.t. variable . Therefore, quantum
(noncommutative) calculations of harmonic oscillators are done by classical
(commutative) ones of the number operator by using the difference theory. As a
by-product, nontrivial relations including the Stirling number of the first
kind are also obtained.Comment: 15 pages, Latex2e, the title before replacement is "Orderings of
Operators in Quantum Physics", new proofs by using a difference operator
added, some references added, to appear in Modern Physics Letters
Synthesis of calculational methods for design and analysis of radiation shields for nuclear rocket systems
Eight computer programs make up a nine volume synthesis containing two design methods for nuclear rocket radiation shields. The first design method is appropriate for parametric and preliminary studies, while the second accomplishes the verification of a final nuclear rocket reactor design
Lorentz transformations that entangle spins and entangle momenta
Simple examples are presented of Lorentz transformations that entangle the
spins and momenta of two particles with positive mass and spin 1/2. They apply
to indistinguishable particles, produce maximal entanglement from finite
Lorentz transformations of states for finite momenta, and describe entanglement
of spins produced together with entanglement of momenta. From the entanglements
considered, no sum of entanglements is found to be unchanged.Comment: 5 Pages, 2 Figures, One new paragraph and reference adde
Realization of an all-optical zero to π cross-phase modulation jump
We report on the experimental demonstration of an all-optical π cross-phase modulation jump. By performing a preselection, an optically induced unitary transformation, and then a postselection on the polarization degree of freedom, the phase of the output beam acquires either a zero or π phase shift (with no other possible values). The postselection results in optical loss in the output beam. An input state may be chosen near the resulting phase singularity, yielding a pi phase shift even for weak interaction strengths. The scheme is experimentally demonstrated using a coherently prepared dark state in a warm atomic cesium vapor
Probing Strong-Field Scalar-Tensor Gravity with Gravitational Wave Asteroseismology
We present an alternative way of tracing the existence of a scalar field
based on the analysis of the gravitational wave spectrum of a vibrating neutron
star. Scalar-tensor theories in strong-field gravity can potentially introduce
much greater differences in the parameters of a neutron star than the
uncertainties introduced by the various equations of state. The detection of
gravitational waves from neutron stars can set constraints on the existence and
the strength of scalar fields. We show that the oscillation spectrum is
dramatically affected by the presence of a scalar field, and can provide unique
confirmation of its existence.Comment: 14 pages, 7 figure
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