957 research outputs found
Air blast parameters close to a liquid propellant explosion
Equations for determining air blast parameters close to liquid propellant explosions, and estimated peak overpressure in close fiel
Nonlinear acoustics
Derivation of equations describing nonlinear acoustics with emphasis on effect of first, second and bulk viscosity coefficient
Air shock parameters and design criteria for rocket explosions
Rocket explosion air blast parameters and design in relation to structural load calculation
Coupling of Transport and Chemical Processes in Catalytic Combustion
Catalytic combustors have demonstrated the ability to operate efficiently over a much wider range of fuel air ratios than are imposed by the flammability limits of conventional combustors. Extensive commercial use however needs the following: (1) the design of a catalyst with low ignition temperature and high temperature stability, (2) reducing fatigue due to thermal stresses during transient operation, and (3) the development of mathematical models that can be used as design optimization tools to isolate promising operating ranges for the numerous operating parameters. The current program of research involves the development of a two dimensional transient catalytic combustion model and the development of a new catalyst with low temperature light-off and high temperature stablity characteristics
Giant-dipole Resonance and the Deformation of Hot, Rotating Nuclei
The development of nuclear shapes under the extreme conditions of high spin
and/or temperature is examined. Scaling properties are used to demonstrate
universal properties of both thermal expectation values of nuclear shapes as
well as the minima of the free energy, which can be used to understand the
Jacobi transition. A universal correlation between the width of the giant
dipole resonance and quadrupole deformation is found, providing a novel probe
to measure the nuclear deformation in hot nuclei.Comment: 6 pages including 6 figures. To appear in Phys. Rev. Lett. Revtex
Magnetic field morphology in nearby molecular clouds as revealed by starlight and submillimetre polarization
Within four nearby (d < 160 pc) molecular clouds, we statistically evaluate
the structure of the interstellar magnetic field, projected on the plane of the
sky and integrated along the line of sight, as inferred from the polarized
thermal emission of Galactic dust observed by Planck at 353 GHz and from the
optical and NIR polarization of background starlight. We compare the dispersion
of the field orientation directly in vicinities with an area equivalent to that
subtended by the Planck effective beam at 353 GHz (10') and using the
second-order structure functions of the field orientation angles. We find that
the average dispersion of the starlight-inferred field orientations within
10'-diameter vicinities is less than 20 deg, and that at these scales the mean
field orientation is on average within 5 deg of that inferred from the
submillimetre polarization observations in the considered regions. We also find
that the dispersion of starlight polarization orientations and the polarization
fractions within these vicinities are well reproduced by a Gaussian model of
the turbulent structure of the magnetic field, in agreement with the findings
reported by the Planck collaboration at scales greater than 10' and for
comparable column densities. At scales greater than 10', we find differences of
up to 14.7 deg between the second-order structure functions obtained from
starlight and submillimetre polarization observations in the same positions in
the plane of the sky, but comparison with a Gaussian model of the turbulent
structure of the magnetic field indicates that these differences are small and
are consistent with the difference in angular resolution between both
techniques.Comment: 15 pages, 10 figures, submitted to A&
Interfering Doorway States and Giant Resonances. II: Transition Strengths
The mixing of the doorway components of a giant resonance (GR) due to the
interaction via common decay channels influences significantly the distribution
of the multipole strength and the energy spectrum of the decay products of the
GR. The concept of the partial widths of a GR becomes ambiguous when the mixing
is strong. In this case, the partial widths determined in terms of the - and
-matrices must be distinguished. The photoemission turns out to be most
sensitive to the overlapping of the doorway states. At high excitation
energies, the interference between the doorway states leads to a restructuring
towards lower energies and apparent quenching of the dipole strength.Comment: 17 pages, LaTeX, 5 figures as JPEG, to appear in PRC (July 1997
Data-driven nonlinear model reduction by moment-matching for the ISWEC system
Given the relevance of control-oriented models in optimal control design for wave energy converters (WECs), this paper presents a data-driven approach to nonlinear model reduction by moment-matching for the ISWEC device, a device originally developed at the Politecnico di Torino. The presented model reduction technique is capable of providing simple WEC models, which inherently preserve steady-state response characteristics from the target nonlinear system, by merely using information on the system outputs, defined for a specific class of operating conditions. We demonstrate that the proposed model reduction by moment-matching procedure is well-posed for the ISWEC, and illustrate the efficacy of this reduction technique under a variety of sea conditions
Combustion instability research Summary report, 1970
Combustion instability in liquid rocket engine
Ecological structure and mapping of Posidonia oceanica meadows in the island of Pantelleria (South Tyrrhenian): a selected site to detect sea wave energy
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