We describe recent experiments in sonic infrared (IR) crack detection in an F‐110 fan disk. This technique uses a single short pulse of sound to cause cracks to heat up and become visible in the infrared. A low frequ...
We describe recent experiments in sonic infrared (IR) crack detection in an F‐110 fan disk. This technique uses a single short pulse of sound to cause cracks to heat up and become visible in the infrared. A low frequency (15 to 40 kHz) ultrasonic transducer fills the sample with sound that causes frictional heating at crack interfaces. We show that the technique can be applied to quite large and irregularly shaped objects like an aircraft engine disk without exciting acoustic mode patterns which might hide cracks in nodal regions.
In this study, a flow control strategy is presented for manipulating coherent shear-flow structures. As a benchmark problem, the transitional flow around a backward-facing step with local acoustic actuation at the upp...
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This paper considers the H ∞ control problem for 2D discrete linear systems with state delays. In particular, a sufficient condition for the existence of an H ∞ state feedback controller for examples described by th...
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This paper considers the H ∞ control problem for 2D discrete linear systems with state delays. In particular, a sufficient condition for the existence of an H ∞ state feedback controller for examples described by the Fornasini-Marchesini and the Roesser state space models with delays is developed in a linear matrix inequality (LMI) setting. Numerical examples are given to illustrate the application of the results developed.
The P-GRADE job execution mode will be demonstrated on a small Grid containing 3 clusters from Budapest and London. The first demonstration illustrates the Grid execution of a parallel meteorology application. The par...
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A model-based flow control strategy is proposed for the suppression of vortex shedding behind a circular cylinder. The control design is based on a hierarchy of low-dimensional Galerkin models of the cylinder wake. Th...
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We investigate necessary and sufficient conditions under which a nonlinear affine control system with outputs can be written as a gradient control system corresponding to some pseudo-Riemannian metric defined on the s...
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We investigate necessary and sufficient conditions under which a nonlinear affine control system with outputs can be written as a gradient control system corresponding to some pseudo-Riemannian metric defined on the state space. The results rely on a suitable notion of compatibility of the system with respect to a given affine connection, and on the input-output behavior of the prolonged system and the gradient extension. The symmetric product associated with an affine connection plays a key role in the discussion
Bit errors and impulses introduced into cardiographic image sequences prohibit to process and evaluate the heart dynamics correctly. Thus, biomedical imaging such as vascular imaging and quantification of heart dynami...
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Bit errors and impulses introduced into cardiographic image sequences prohibit to process and evaluate the heart dynamics correctly. Thus, biomedical imaging such as vascular imaging and quantification of heart dynamics is closely related to digital filtering. We provide three-dimensional impulse detection based adaptive median filters designed to perform the optimal filtering situation, where the robust median filter affects only noisy samples, whereas the desired image features remains unchanged. The proposed method holds excellent preserving characteristics and takes the advantage of the superposition property despite the nonlinearity of the median filtering.
Tremor denotes an involuntary, approximately rhythmic, and roughly sinusoidal movement of parts of the body. Pathological tremors result from disorders of the central nervous system and peripheral nervous system. In t...
Tremor denotes an involuntary, approximately rhythmic, and roughly sinusoidal movement of parts of the body. Pathological tremors result from disorders of the central nervous system and peripheral nervous system. In this paper we study the two most common pathological tremors, essential and Parkinsonian, using dynamical systems theory. We show that pathological tremors can be characterized as diffusional processes. The time scale range for the diffusional scaling law to be valid starts from about one to several tens of the mean oscillation period. This time scale range contrasts sharply with the predictable time scale for deterministic chaos, which is usually only a small fraction of the mean oscillation period. The mechanism for pathological tremors is also discussed, based on fractal and bifurcation theory.
Repetitive processes are a distinct class of 2D linear systems with applications in areas ranging from long-wall coal cutting and metal rolling operations through to iterative learning control schemes. The main featur...
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