16,677 research outputs found
Continuous Non-Demolition Observation, Quantum Filtering and Optimal Estimation
A quantum stochastic model for an open dynamical system (quantum receiver)
and output multi-channel of observation with an additive nonvacuum quantum
noise is given. A quantum stochastic Master equation for the corresponding
instrument is derived and quantum stochastic filtering equations both for the
Heisenberg operators and the reduced density matrix of the system under the
nondemolition observation are found. Thus the dynamical problem of quantum
filtering is generalized for a noncommutative output process, and a quantum
stochastic model and optimal filtering equation for the dynamical estimation of
an input Markovian process is found. The results are illustrated on an example
of optimal estimation of an input Gaussian diffusion signal, an unknown
gravitational force say in a quantum optical or Weber's antenna for detection
and filtering a gravitational waves.Comment: A revised version of the paper published in the Proceedings of the
1st QCMC conference, Paris 199
Mass Generation in the Supersymmetric Nambu--Jona--Lasinio Model in an External Magnetic Field
The mass generation in the (3+1)-dimensional supersymmetric
Nambu-Jona-Lasinio model in a constant magnetic field is studied. It is shown
that the external magnetic field catalyzes chiral symmetry breaking.Comment: LaTeX file, 6 pages. Talk given at the International Seminar
dedicated to the memory of Dmitrij Volkov "Supersymmetry and Quantum Field
Theory", Kharkov, Ukraine, January 5-7, 199
Some data on the predacious behaviour of tendipidae larvae [Translation from: C. R. Acad. Sci. U.R.S.S. 111, 466-4, 1956]
A study has been made primarily of the food of the chironomid Procladius nigriventris: this includes Alona affinis, Bosmina coregoni, Camptocercus, Eucyclops serrulatus, Paracyclops fimbriatus, Acanthocyclops viridis, Harpacticoida, Diaptomus graciloides, Ostracods, Chironomus sp, Polypedilum sp and Tanytarsus sp. Chironomus larvae usually found in the gut are in their 1st or 2nd instars , though occasional 3rd instars are present. The study summarises other findings on the feeding behaviour of Procladius nigriventris
Variational principle for frozen-in vortex structures interacting with sound waves
General properties of conservative hydrodynamic-type models are treated from
positions of the canonical formalism adopted for liquid continuous media, with
applications to the compressible Eulerian hydrodynamics, special- and
general-relativistic fluid dynamics, and two-fluid plasma model including the
Hall-magnetohydrodynamics. A variational formulation is found for motion and
interaction of frozen-in localized vortex structures and acoustic waves in a
special description where dynamical variables are, besides the Eulerian fields
of the fluid density and the potential component of the canonical momentum,
also the shapes of frozen-in lines of the generalized vorticity. This
variational principle can serve as a basis for approximate dynamical models
with reduced number of degrees of freedom.Comment: 7 pages, revtex4, no figure
-models on the quantum group manifolds , , and infinitesimal trasformations
The differential and variational calculus on the group is
constructed. The spontaneous breaking symmetry in the WZNW model with
quantum group symmetry and in the -models with
, quantum group symmetry is considered.
The Lagrangian formalism over the quantum group manifolds is discussed. The
classical solution of {}-model is obtained.Comment: LaTex, 7 page
Generalized detector as a spectrum sensor in cognitive radio networks
The implementation of the generalized detector (GD) in cognitive radio (CR) systems allows us to improve the spectrum sensing performance in comparison with employment of the conventional detectors. We analyze the spectrum sensing performance for the uncorrelated and spatially correlated receive antenna array elements. Addi¬tionally, we consider a practical case when the noise power at the output of GD linear systems (the preliminary and additional filters) is differed by value. The choice of the optimal GD threshold based on the minimum total error rate criterion is also discussed. Simulation results demonstrate superiority of GD implementation in CR sys¬tem as spectrum sensor in comparison with the energy detector (ED), weighted ED (WED), maximum-minimum eigenvalue (MME) detector, and generalized likelihood ratio test (GLRT) detecto
Refrigerant and Oil Migration and Retention in Air Conditioning and Refrigeration Systems
Air Conditioning and Refrigeration Project 16
Energy flux through the horizon in the black hole-domain wall systems
We study various configurations in which a domain wall (or cosmic string),
described by the Nambu-Goto action, is embedded in a background space-time of a
black hole in and higher dimensional models. We calculate energy fluxes
through the black hole horizon. In the simplest case, when a static domain wall
enters the horizon of a static black hole perperdicularly, the energy flux is
zero. In more complicated situations, where parameters which describe the
domain wall surface are time and position dependent, the flux is non-vanishing
is principle. These results are of importance in various conventional
cosmological models which accommodate the existence of domain walls and strings
and also in brane world scenarios.Comment: references added, accepted for publication in JHE
The hodograph method applicability in the problem of long-scale nonlinear dynamics of a thin vortex filament near a flat boundary
Hamiltonian dynamics of a thin vortex filament in ideal incompressible fluid
near a flat fixed boundary is considered at the conditions that at any point of
the curve determining shape of the filament the angle between tangent vector
and the boundary plane is small, also the distance from a point on the curve to
the plane is small in comparison with the curvature radius. The dynamics is
shown to be effectively described by a nonlinear system of two
(1+1)-dimensional partial differential equations. The hodograph transformation
reduces that system to a single linear differential equation of the second
order with separable variables. Simple solutions of the linear equation are
investigated at real values of spectral parameter when the filament
projection on the boundary plane has shape of a two-branch spiral or a smoothed
angle, depending on the sign of .Comment: 9 pages, revtex4, 6 eps-figure
Thomas Decomposition of Algebraic and Differential Systems
In this paper we consider disjoint decomposition of algebraic and non-linear
partial differential systems of equations and inequations into so-called simple
subsystems. We exploit Thomas decomposition ideas and develop them into a new
algorithm. For algebraic systems simplicity means triangularity, squarefreeness
and non-vanishing initials. For differential systems the algorithm provides not
only algebraic simplicity but also involutivity. The algorithm has been
implemented in Maple
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