50,343 research outputs found
The reliability of the All-Up concept Special technical report no. 13
Implementation approaches for conducting Saturn V launch vehicle program without dummy stage
The stability of solitons in biomembranes and nerves
We examine the stability of a class of solitons, obtained from a
generalization of the Boussinesq equation, which have been proposed to be
relevant for pulse propagation in biomembranes and nerves. These solitons are
found to be stable with respect to small amplitude fluctuations. They emerge
naturally from non-solitonic initial excitations and are robust in the presence
of dissipation.Comment: 7 pages, 5 figure
Stability of a non-orthogonal stagnation flow to three dimensional disturbances
A similarity solution for a low Mach number nonorthogonal flow impinging on a hot or cold plate is presented. For the constant density case, it is known that the stagnation point shifts in the direction of the incoming flow and that this shift increases as the angle of attack decreases. When the effects of density variations are included, a critical plate temperature exists; above this temperature the stagnation point shifts away from the incoming stream as the angle is decreased. This flow field is believed to have application to the reattachment zone of certain separated flows or to a lifting body at a high angle of attack. Finally, the stability of this nonorthogonal flow to self similar, 3-D disturbances is examined. Stability properties of the flow are given as a function of the parameters of this study; ratio of the plate temperature to that of the outer potential flow and angle of attack. In particular, it is shown that the angle of attack can be scaled out by a suitable definition of an equivalent wavenumber and temporal growth rate, and the stability problem for the nonorthogonal case is identical to the stability problem for the orthogonal case
Cerenkov's Effect and Neutrino Oscillations in Loop Quantum Gravity
Bounds on the scale parameter {\cal L} arising in loop quantum gravity theory
are derived in the framework of Cerenkov's effect and neutrino oscillations.
Assuming that {\cal L} is an universal constant, we infer {\cal L}>
10^{-18}eV^{-1}, a bound compatible with ones inferred in different physical
context.Comment: 6 pages, no figures, in print on MPL
Comment on `About the magnetic field of a finite wire'
A flaw is pointed out in the justification given by Charitat and Graner [2003
Eur. J. Phys. vol. 24, 267] for the use of the Biot--Savart law in the
calculation of the magnetic field due to a straight current-carrying wire of
finite length.Comment: REVTeX, 3 pages. A slightly expanded version that has been accepted
for publication by Eur. J. Phy
Spectra of Magnetic Fields Injected during Baryogenesis
Helical magnetic fields are injected into the cosmic medium during
cosmological baryogenesis and can potentially provide a useful probe of the
early universe. We construct a model to study the injection process during a
first order phase transition and to determine the power spectra of the injected
magnetic field. By Monte Carlo simulations we evaluate the Fourier space
symmetric and helical power spectra of the magnetic field at the time the phase
transition completes. The spectra are peaked at the scale given by the inverse
size of bubbles at percolation and with a comparable width. These injected
magnetic fields set the initial conditions for further cosmological
magneto-hydrodynamical evolution.Comment: 8 pages, 9 figures; revised discussion and added new references;
version accepted for publication in PR
Curved cap corrugated sheet
The report describes a structure for a strong, lightweight corrugated sheet. The sheet is planar or curved and includes a plurality of corrugation segments, each segment being comprised of a generally U-shaped corrugation with a part-cylindrical crown and cap strip, and straight side walls and with secondary corrugations oriented at right angles to said side walls. The cap strip is bonded to the crown and the longitudinal edge of said cap strip extends beyond edge at the intersection between said crown and said side walls. The high strength relative to weight of the structure makes it desirable for use in aircraft or spacecraft
Finding the Pion in the Chiral Random Matrix Vacuum
The existence of a Goldstone boson is demonstrated in chiral random matrix
theory. After determining the effective coupling and calculating the scalar and
pseudoscalar propagators, a random phase approximation summation reveals the
massless pion and massive sigma modes expected whenever chiral symmetry is
spontaneously broken.Comment: 3 pages, 1 figure, revte
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