7,714 research outputs found
Some results on the use of the LANDSAT-1 multispectral images
There are no author-identified significant results in this report
Brazil's remote sensing activities in the Eighties
Most of the remote sensing activities in Brazil have been conducted by the Institute for Space Research (INPE). This report describes briefly INPE's activities in remote sensing in the last years. INPE has been engaged in research (e.g., radiance studies), development (e.g., CCD-scanners, image processing devices) and applications (e.g., crop survey, land use, mineral resources, etc.) of remote sensing. INPE is also responsible for the operation (data reception and processing) of the LANDSATs and meteorological satellites. Data acquisition activities include the development of CCD-Camera to be deployed on board the space shuttle and the construction of a remote sensing satellite
Persistence of periodic solutions for higher order perturbed differential systems via Lyapunov-Schmidt reduction
In this work we first provide sufficient conditions to assure the persistence
of some zeros of functions having the form
for sufficiently
small. Here , for , are
smooth functions being an open bounded set.
Then we use this result to compute the bifurcation functions which controls the
periodic solutions of the following -periodic smooth differential system It is assumed that the
unperturbed differential system has a sub-manifold of periodic solutions
, . We also study the case when
the bifurcation functions have a continuum of zeros. Finally we provide the
explicit expressions of the bifurcation functions up to order 5
Fermion Helicity Flip in Weak Gravitational Fields
The helicity flip of a spin- Dirac particle
interacting gravitationally with a scalar field is analyzed in the context of
linearized quantum gravity. It is shown that massive fermions may have their
helicity flipped by gravity, in opposition to massless fermions which preserve
their helicity.Comment: RevTeX 3.0, 8 pages, 3 figures (available upon request), Preprint
IFT-P.013/9
Melnikov analysis in nonsmooth differential systems with nonlinear switching manifold
We study the family of piecewise linear differential systems in the plane
with two pieces separated by a cubic curve. Our main result is that 7 is a
lower bound for the Hilbert number of this family. In order to get our main
result, we develop the Melnikov functions for a class of nonsmooth differential
systems, which generalizes, up to order 2, some previous results in the
literature. Whereas the first order Melnikov function for the nonsmooth case
remains the same as for the smooth one (i.e. the first order averaged function)
the second order Melnikov function for the nonsmooth case is different from the
smooth one (i.e. the second order averaged function). We show that, in this
case, a new term depending on the jump of discontinuity and on the geometry of
the switching manifold is added to the second order averaged function
Three Jet Events and New Strong Couplings at LEP and NLC
We study the effects of new dimension--6 operators, resulting from a general
invariant effective Lagrangian, on
three jet production at LEP and at the Next Linear Collider. Contributions to
the total event rate and to some event shape variables are analysed in order to
establish bounds on these operators.Comment: 5 pages, LaTeX, 1 Figur
Regularization of hidden dynamics in piecewise smooth flows
This paper studies the equivalence between differentiable and
non-differentiable dynamics in Rn. Filippov's theory of discontinuous
differential equations allows us to find flow solutions of dynamical systems
whose vector fields undergo switches at thresholds in phase space. The
canonical convex combination at the discontinuity is only the linear part of a
nonlinear combination that more fully explores Filippov's most general problem:
the differential inclusion. Here we show how recent work relating discontinuous
systems to singular limits of continuous (or regularized) systems extends to
nonlinear combinations. We show that if sliding occurs in a discontinuous
systems, there exists a differentiable slow-fast system with equivalent slow
invariant dynamics. We also show the corresponding result for the pinching
method, a converse to regularization which approximates a smooth system by a
discontinuous one
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