36,432 research outputs found
Radiation-reaction-induced evolution of circular orbits of particles around Kerr Black Holes
It is demonstrated that, in the adiabatic approximation, non-Equatorial
circular orbits of particles in the Kerr metric (i.e. orbits of constant
Boyer-Lindquist radius) remain circular under the influence of gravitational
radiation reaction. A brief discussion is given of conditions for breakdown of
adiabaticity and of whether slightly non-circular orbits are stable against the
growth of eccentricity.Comment: 23 pages. Revtex 3.0. Inquiries to [email protected]
Optomechanical cooling in a continuous system
Radiation-pressure-induced optomechanical coupling permits exquisite control
of micro- and mesoscopic mechanical oscillators. This ability to manipulate and
even damp mechanical motion with light---a process known as dynamical
backaction cooling---has become the basis for a range of novel phenomena within
the burgeoning field of cavity optomechanics, spanning from dissipation
engineering to quantum state preparation. As this field moves toward more
complex systems and dynamics, there has been growing interest in the prospect
of cooling traveling-wave phonons in continuous optomechanical waveguides.
Here, we demonstrate optomechanical cooling in a continuous system for the
first time. By leveraging the dispersive symmetry breaking produced by
inter-modal Brillouin scattering, we achieve continuous mode optomechanical
cooling in an extended 2.3-cm silicon waveguide, reducing the temperature of a
band of traveling-wave phonons by more than 30 K from room temperature. This
work reveals that optomechanical cooling is possible in macroscopic linear
waveguide systems without an optical cavity or discrete acoustic modes.
Moreover, through an intriguing type of wavevector-resolved phonon
spectroscopy, we show that this system permits optomechanical control over
continuously accessible groups of phonons and produces a new form of
nonreciprocal reservoir engineering. Beyond this study, this work represents a
first step towards a range of novel classical and quantum traveling-wave
operations in continuous optomechanical systems.Comment: Manuscript with supplementary information. 17 pages, 4 Figures. Minor
correction in Fig.
System analysis approach to deriving design criteria (loads) for Space Shuttle and its payloads. Volume 1: General statement of approach
Space shuttle, the most complex transportation system designed to date, illustrates the requirement for an analysis approach that considers all major disciplines simultaneously. Its unique cross coupling and high sensitivity to aerodynamic uncertainties and high performance requirements dictated a less conservative approach than those taken in programs. Analyses performed for the space shuttle and certain payloads, Space Telescope and Spacelab, are used a examples. These illustrate the requirements for system analysis approaches and criteria, including dynamic modeling requirements, test requirements control requirements and the resulting design verification approaches. A survey of the problem, potential approaches available as solutions, implications for future systems, and projected technology development areas are addressed
System analysis approach to deriving design criteria (Loads) for Space Shuttle and its payloads. Volume 2: Typical examples
The achievement of an optimized design from the system standpoint under the low cost, high risk constraints of the present day environment was analyzed. Space Shuttle illustrates the requirement for an analysis approach that considers all major disciplines (coupling between structures control, propulsion, thermal, aeroelastic, and performance), simultaneously. The Space Shuttle and certain payloads, Space Telescope and Spacelab, are examined. The requirements for system analysis approaches and criteria, including dynamic modeling requirements, test requirements, control requirements, and the resulting design verification approaches are illustrated. A survey of the problem, potential approaches available as solutions, implications for future systems, and projected technology development areas are addressed
Templates for stellar mass black holes falling into supermassive black holes
The spin modulated gravitational wave signals, which we shall call smirches,
emitted by stellar mass black holes tumbling and inspiralling into massive
black holes have extremely complicated shapes. Tracking these signals with the
aid of pattern matching techniques, such as Wiener filtering, is likely to be
computationally an impossible exercise. In this article we propose using a
mixture of optimal and non-optimal methods to create a search hierarchy to ease
the computational burden. Furthermore, by employing the method of principal
components (also known as singular value decomposition) we explicitly
demonstrate that the effective dimensionality of the search parameter space of
smirches is likely to be just three or four, much smaller than what has
hitherto been thought to be about nine or ten. This result, based on a limited
study of the parameter space, should be confirmed by a more exhaustive study
over the parameter space as well as Monte-Carlo simulations to test the
predictions made in this paper.Comment: 12 pages, 4 Tables, 4th LISA symposium, submitted to CQ
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