622 research outputs found

    A new approach to transport equations associated to a regular field: trace results and well-posedness

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    We generalize known results on transport equations associated to a Lipschitz field F\mathbf{F} on some subspace of RN\mathbb{R}^N endowed with some general space measure μ\mu. We provide a new definition of both the transport operator and the trace measures over the incoming and outgoing parts of ∂Ω\partial \Omega generalizing known results from the literature. We also prove the well-posedness of some suitable boundary-value transport problems and describe in full generality the generator of the transport semigroup with no-incoming boundary conditions.Comment: 30 page

    Assembly of objects with not fully predefined shapes

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    An assembly problem in a non-deterministic environment, i.e., where parts to be assembled have unknown shape, size and location, is described. The only knowledge used by the robot to perform the assembly operation is given by a connectivity rule and geometrical constraints concerning parts. Once a set of geometrical features of parts has been extracted by a vision system, applying such a rule allows the dtermination of the composition sequence. A suitable sensory apparatus allows the control the whole operation

    Non-autonomous Honesty theory in abstract state spaces with applications to linear kinetic equations

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    We provide a honesty theory of substochastic evolution families in real abstract state space, extending to an non-autonomous setting the result obtained for C0C_0-semigroups in our recent contribution \textit{[On perturbed substochastic semigroups in abstract state spaces, \textit{Z. Anal. Anwend.} \textbf{30}, 457--495, 2011]}. The link with the honesty theory of perturbed substochastic semigroups is established. Several applications to non-autonomous linear kinetic equations (linear Boltzmann equation and fragmentation equation) are provided

    Integral representation of the linear Boltzmann operator for granular gas dynamics with applications

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    We investigate the properties of the collision operator associated to the linear Boltzmann equation for dissipative hard-spheres arising in granular gas dynamics. We establish that, as in the case of non-dissipative interactions, the gain collision operator is an integral operator whose kernel is made explicit. One deduces from this result a complete picture of the spectrum of the collision operator in an Hilbert space setting, generalizing results from T. Carleman to granular gases. In the same way, we obtain from this integral representation of the gain operator that the semigroup in L^1(\R \times \R,\d \x \otimes \d\v) associated to the linear Boltzmann equation for dissipative hard spheres is honest generalizing known results from the first author.Comment: 19 pages, to appear in Journal of Statistical Physic
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