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Bartłomiej Garda - IEEE Xplore Author Profile

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In this work the problem of designing the optimal coil for the homogeneous magnetic field excitation is considered. Such coils are used for example in the magnetic resonance imaging systems. The studied problem formulation belongs to the class of the box-constrained non-linear optimization problem. This kind of optimization problem requires calling the objective function many times and in conseque...Show More
The problem of memristors modeling is investigated. The elements under study are self-directed-channel memristors with a tungsten dopant fabricated by the Knowm Inc. Memristors are exited using a sinusoidal waveform. Three memristor models are considered: the asymmetric Strukov model, the Strukov model with the Biolek window, and the VTEAM model. Parameters of the models are fitted to experimental...Show More
In this work, the problem of memristors modeling is investigated. The elements under study are self-directed-channel memristors with a tungsten dopant fabricated by the Knowm Inc. Memristors are exited using a sinusoidal waveform. Three existing memristor models are considered: the Strukov model, the Biolek model, and the VTEAM model. Additionally, an asymmetric Strukov model is considered. Parame...Show More
We present results of time-domain laboratory measurements of memristive devices. We study the dynamics of the process of memristor forming and investigate switching mechanisms in memristors. Measurement results are compared with a standard model of oxide-based memristor. We confirm that endurance may be a problem for this type of memristors.Show More
Construction of memristive memories requires usage of stable and reliable individual memory devices. So far several technologies were tested to implement the memristive RRAM elements. Many of these use the metal-oxide/metal junctions. In this paper we look into dynamic phenomena encountered in real memristors realised as solid state devices in the Pt/HfO2/Ti/Pt technology. We test the forming beha...Show More
In this paper the problem of existence of parasitic components in a real memristor has been analysed. These unwanted components have some impacts on behaviour of the memristors causing discrepancies in the observed dynamic characteristics. To model this kind of behaviour additional L and C elements have to be introduced in the memristor model. Simulation tests have been carried out to uncover the ...Show More
A systematic method to find all low-period windows for the logistic map fa(x) = ax(1 - x) is proposed. The method is used to obtain very good approximations of positions of periodic windows with periods p ≤ 20. For each window using the forward shooting based interval Newton operator we confirm its existence by proving the existence of a sink for several parameter values inside the window and comp...Show More
In the design of coils for magnetic resonance imaging devices the radial field component is usually neglected, and in the optimization procedure the currents and positions of simple coils are found to minimize the error between the axial component and the required magnetic field in the region of interest. In this work, we consider two cases of the required magnetic field both of which are needed i...Show More
The problem to find the shape of the coil to obtain the required magnetic field in a given area is studied. It is assumed that the coil has cylindrical symmetry, and that the current density in the coil is fixed. Two cases of the shape of the target area are considered. When the target area is located on the coil axis, the problem can be simplified by using analytical formula for the magnetic fiel...Show More
In this work, the problem of constrained coil design is studied. Two approaches to this problem, namely the non-negative least squares method (NNLSQ) and the Tikhonov regularization technique, are compared. Several one-dimensional and two-dimensional examples are considered. It is shown that the constrained LSQ method outperforms the Tikhonov regularization based approach both in terms of the qual...Show More