KEYWORDS: Principal component analysis, Visualization, Data modeling, Statistical modeling, Temperature metrology, Structural health monitoring, Sensors, Statistical analysis, Environmental sensing, Aluminum
This paper explores the use of Principal Component Analysis (PCA), an extended form of PCA and, the T2-statistic and Q-statistic; distances that detect and distinguish damages in structures under varying operational
and environmental conditions. The work involves an experiment in which two piezoelectric transducers are
bonded on an aluminium plate. The plate is subjected to several damages and exposed to different levels of
temperature. A series of tests have been performed for each condition. The approach is able to determine
whether the structure has damage or not, and besides, gives qualitative information about its size, isolating
effects of the temperature.
This paper presents a new form of the Bouc-Wen model called the normalized one. This form appears as a result of the analytical description of the limit cycle. The parameters that appear in this new form are the ones that influence in a direct way the shape of the hysteresis loop. This paper explores the relationship between these parameters and the behavior of the limit cycle.
This paper addresses the problem of formulating a feedback control
law for the semiactive control of a class of two-span bridge,
which is equipped with controllable friction devices at the joints
between the columns and the deck. A finite element model is
available to represent the essential dynamical features of the
bridge. Based on this model, a Lyapunov-based robust semiactive
control law is designed, which uses feedback from the nodes where
the devices are located. Two sources of uncertainties are
considered in the design: a first order actuator dynamics and a
seismic excitation at the column supports. After the formulation
of the control law, numerical tests are performed to assess the
efficiency of the control scheme to reduce the response of the
bridge.
A backstepping-based adaptive control is designed for a class of
one degree of freedom hysteretic system. The true hysteretic
behavior does not need to be known for the controller design. A
polynomial description is assumed with uncertain coefficients and
an uncertain residual function. These uncertainties are bounded
and lump the discrepancies between the adopted description and the
real hysteretic behavior. The adaptive controller is able to
handle these uncertainties and make the closed loop globally
uniformly ultimately bounded when the system is subject to an
unknown excitation from which a bound is known. The efficiency of
the approach is tested by numerical simulations on a hysteretic
system under a seismic excitation. This system is mathematically
described by the differential Bouc-Wen model, which is widely used
in structural dynamics.
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