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The -Bell numbers
The notion of generalized Bell numbers has appeared in several works but
there is no systematic treatise on this topic. In this paper we fill this gap.
We discuss the most important combinatorial, algebraic and analytic properties
of these numbers which generalize the similar properties of the Bell numbers.
Most of these results seem to be new. It turns out that in a paper of Whitehead
these numbers appeared in a very different context. In addition, we introduce
the so-called -Bell polynomials
Unitary transformations for testing Bell inequalities
It is shown that optical experimental tests of Bell inequality violations can
be described by SU(1,1) transformations of the vacuum state, followed by photon
coincidence detections. The set of all possible tests are described by various
SU(1,1) subgroups of Sp(8,). In addition to establishing a common
formalism for physically distinct Bell inequality tests, the similarities and
differences of post--selected tests of Bell inequality violations are also made
clear. A consequence of this analysis is that Bell inequality tests are
performed on a very general version of SU(1,1) coherent states, and the
theoretical violation of the Bell inequality by coincidence detection is
calculated and discussed. This group theoretical approach to Bell states is
relevant to Bell state measurements, which are performed, for example, in
quantum teleportation.Comment: 3 figure
Bell polynomials in combinatorial Hopf algebras
We introduce partial -Bell polynomials in three combinatorial Hopf
algebras. We prove a factorization formula for the generating functions which
is a consequence of the Zassenhauss formula.Comment: 7 page
Non-linear fe modelling of seismic pounding and damped-mitigating interconnection between a r/c tower and a masonry church
The finite element analysis of pounding represents one of the most critical issues for the assessment of the seismic performance of R/C structures built at poor distance from adjacent buildings. The effects of pounding can be particularly severe in slender R/C heritage structures, including civic or bell towers. An emblematic case study falling in this class of structures, i.e. a monumental R/C bell tower constructed in the early 1960s in Florence, is analyzed in this paper. Pounding collisions are simulated with a multi-link viscoelastic contact model originally implemented in this study. The results of the non-linear dynamic enquiry carried out with this model show that pounding affects the seismic response of the bell tower and the adjacent church as early as an input seismic action scaled at the amplitude of the normative basic design earthquake level. A retrofit hypothesis to prevent pounding is then proposed, which consists in linking the two structures by means of a pair of fluid-viscous dissipaters. Thanks to the supplemental damping action produced by these devices, the impacts are totally annulled, bringing the structural members of the tower to safe levels
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