692 research outputs found
Novel Design of a Model Reference Adaptive Controller for Soft Tissue Operations
Model Reference Adaptive Controllers
(MRAC) have
dual functionality: besides guaranteeing precise trajectory track-
ing of the controlled system, they have to provide an “external
control loop” with the illusion that it controls a physical system of
prescribed dynamic properties, i.e., the “reference system”. The
MRACs are designed traditionally by
Lyapunov’s 2
nd
method
that
is mathematically complicated, requiring strong skills from the
designer. Adaptive controllers alternatively designed by the use
of
Robust Fixed Point Transformations
(RFPT) operate according
to
Banach’s Fixed Point Theorem
, and are normally simple
iterative constructions that also have a standard variant for
MRAC design. This controller assumes a single actuator that
is driven adaptively.
Master–Slave Systems
form a distinct class
of practical applications, in which two arms—the master and the
slave—operate simultaneously. The movement of the master must
be tracked precisely by the slave in spite of the quite different
forces exerted by them. In the present paper, a soft tissue-cutting
operation by a master–slave structure is simulated. The master
arm has a simple torque–reference friction model, and is driven
by the surgeon. The obtained master arm trajectory has to be
precisely tracked by the electric DC motor driven slave system,
which is in dynamic interaction with the actual tissue under
operation. It is shown via simulations that the RFPT-based design
can efficiently solve such tasks without considerable mathematical
complexity
Compilation of isomeric ratios of light particle induced nuclear reactions
Experimental isomeric ratios of light (A4) particle-induced nuclear
reactions were compiled for the product nuclides having metastable states with
half-lives longer than 0.1 sec. The experimental isomeric ratio data were taken
from the EXFOR library and reviewed. When an experiment reports isomer
production cross sections instead of isomeric ratios, the cross sections taken
from the EXFOR library were converted to the isomeric ratios by us. During
compilation, questionable data (e.g.,preliminary data compiled in EXFOR in
parallel with their final data, sum of isomer production cross sections larger
than the total production cross sections) were excluded. As an application of
the new compilation, goodness-of-fit was studied for the isomeric ratios
predicted by the reaction model code TALYS-1.96
Asymptotic scattering and duality in the one-dimensional three-state quantum Potts model on a lattice
We determine numerically the single-particle and the two-
particle spectrum of the three-state quantum Potts model on a
lattice by using the density matrix renormalization group
method, and extract information on the asymptotic (small
momentum) S-matrix of the quasiparticles. The low energy part of
the finite size spectrum can be understood in terms of a simple
effective model introduced in a previous work, and is consistent
with an asymptotic S-matrix of an exchange form below a momentum
scale p*. This scale appears to vanish faster than the Compton
scale, mc, as one approaches the critical point, suggesting that
a dangerously irrelevant operator may be responsible for the
behaviour observed on the lattice
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