Ralf L. M. Peeters

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This paper deals with the problem of computing a best rational L 2 approximation of specified order to a given multivariable transfer function. The problem is equivalently formulated as a minimization problem over the manifold of lossless transfer functions of fixed order. To describe this manifold, we use some Schur parameters which allows for a(More)
— This paper presents an analog implementation of the complex wavelet transform using both the complex first order system (CFOS) and the Padé approximation. The complex wavelet filter design is based on the combination of the real and the imaginary state-space descriptions that implement the respective transfer functions. In other words, a complex filter is(More)
The problem of finding the global minimum of a so-called Minkowski-norm dominated polynomial can be approached by the matrix method of Stetter-Möller, which reformulates it as a large eigenvalue problem. A drawback of this approach is that the matrix involved is usually very large. However, all that is needed for modern iterative eigenproblem solvers (such(More)
Beat-to-beat variability of repolarization duration (BVR) is an intrinsic characteristic of cardiac function and a better marker of proarrhythmia than repolarization prolongation alone. The ionic mechanisms underlying baseline BVR in physiological conditions, its rate dependence, and the factors contributing to increased BVR in pathologies remain(More)
In this paper, the connections are investigated between two diierent approaches towards the parametrization of multivariable stable all-pass systems in discrete-time. The rst approach involves the tangential Schur algorithm, which employs linear fractional transformations. It stems from the theory of reproducing kernel Hilbert spaces and enables the direct(More)
—Signal processing by means of analog circuits offers advantages from a power consumption viewpoint. A method is described to implement wavelets in analog circuits by fitting the impulse response of a linear system to the time-reversed wavelet function. The fitting is performed using local search involving an 2 criterion, starting from a deterministic(More)
Noninvasive imaging of electrical activity of the heart has increasingly gained attention last decades. Heart-surface potentials are reconstructed from a torso-heart geometry and body-surface potentials recorded from tens to hundreds of body-surface electrodes. However, it remains an open question how many electrodes are needed to accurately reconstruct(More)
The objective of the inverse problem of electrocardiography is to noninvasively reconstruct information about electrical activity at the heart surface (epicardium), from electrical measurements on the body surface and a patient-specific torso-heart geometry. This is complicated by the ill-posedness of the inverse problem. Previously, we have shown that a(More)