Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"Piotr ZEGARMISTRZ"

Analityczne algorytmy rekonstrukcji konduktancji w prostokątnych siatkach rezystorów

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W pracy przedstawiono wyniki analizy algorytmów rekonstrukcji konduktancji prostokątnych siatek rezystorów na podstawie pomiarów brzegowych. Zbadano stabilność numeryczną algorytmu zaproponowanego przez Curtisa i Morrowa. Przetestowano działanie algorytmu w przypadku istnienia błędów pomiarowych. Wykazano, że błędy pomiarów znacząco wpływają na poprawność rekonstrukcji nawet dla siatek o niewielkich rozmiarach oraz że algorytm jest niestabilny numerycznie dla siatek o większych rozmiarach. Zaproponowano szereg modyfikacji algorytmu rekonstrukcji oraz porównano efekty działania wersji z usprawnieniami oraz oryginalnej. Abstract. In this work the problem of reconstruction of conductances in rectangular resistor grids from boundary measurements is investigated. The algorithm proposed by Curtis and Morrow is studied in terms of numerical stability. Algorithm’s performance in the presence of measurement errors is tested. It is shown that measurement errors can deteriorate the performance of the algorithm even for small grid sizes and that the algorithm is numerically unstable for larger grids. Several methods for improving the algorithm are proposed. The performance of the modified versions are tested. (Analytic Algorithms for Reconstruction of Conductances in Rectangular Resistive Grids). Słowa kluczowe: siatka rezystorów, algorytmy rekonstrukcji, tomografia rezystancyjna. Keywords: resistive grid, reconstruction algorithm, resistance tomography. Wstęp W pracy rozważany jest problem rekonstrukcji konduktancji siatek rezystorów na podstawie pomiarów brzegowych [1, 2, 3]. Istotą problemu rekonstrukcji jest wyznaczenie wartości konduktancji elementów łączących węzły siatki przy założeniu, że istnieje dostęp tylko do węzłów brzegowych. Rozważany problem ma praktyczne zastosowania w sytuacjach, gdy siatka elementów rezystancyjnych jest wykorzystywana do wyznaczenia rozkładu ciężaru, temperatury lub innych parametrów fizycznych danej pow[...]

Memristive Devices In Three-Phase Systems DOI:10.15199/48.2020.01.03

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Theoretical definition of memristor was stated by L.O. Chua in 1971 [1][2]. It was defined as an element in which the actual value of resistance depends on the flux or charge through the element. It is capable of switching between two resistance states upon application of an appropriate voltage or current signal that can be sensed by applying a relatively much smaller sensing signal [3]. It was announced as the missing fourth fundamental passive circuit element. In 2008 HP Laboratories reported the discovery of the element, which exhibits electrically controllable statedependent resistance [3][4]. It was a turning point in research on memristive devices. This topic became a priority for many R&D units and academic researchers. The most crucial property of memristor is the fact, that it can take two significantly different values of resistance in a stable way. This explains, why after 2008 this topic became so popular for scientists specializing in electronics, in particular memories, logic circuits and neuromorphic systems [5]. However, the applications of memrsitive devices focuses on microelectronics, that is not the one and only correct direction. In recent years the concept of so-called ’power memristor’ grows. The idea is to use memristive elements in lightning protection systems, i.e. instead of traditional varistors. In [6] author proposes a combined over-voltage protecting device consisting of a memristor connected in series with a spark gap. The memristor is applied for dissipating lightning surge energy and for breaking the short circuit current. This simple example shows, that analyzing the usage of memristive device in three-phase systems is noteworthy and can deliver a basis for further research. A characteristic pinched hystersis loop (so-called bowtie curve) in v-i relation when applying a sinusoidal voltage to the element is also a special mark for memristors. This v-i histeresis loop always pass[...]

Study of Forming Process in Memristive Devices using Rectangular DOI:10.15199/48.2020.01.04

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Theoretical definition of memristor was formulated in [1, 2]. The memristor is defined as an element in which the resistance depends on the history of flux or charge of the element. Memristors are capable of changing the resistance after application of an appropriate voltage or current signal. The value of the resistance can be measured by applying a relatively much smaller sensing signal [3]. The discovery of the element, which exhibits electrically controllable state-dependent resistance was reported in [3, 4]. It was a turning point in research on memristive devices. The most crucial property of memristor is the fact, that it can take two significantly different values of resistance in a stable way. This explains, why this topic became very popular for scientists specializing in electronics, memories, logic circuits and neuromorphic systems [5]. When a sinusoidal voltage is applied to the element a characteristic pinched hysteresis loop (also called the bow-tie curve) in v-i relation is observed (see Fig. 1). This v-i hysteresis loop always passes through the origin for any bipolar periodic input voltage. The pinched hysteresis loop narrows down when the frequency f is increased and the area of the loop converges to zero when f grows to infinity [6]. The main aim of this work is the study of memristors during the procedure of forming the element, i.e. setting the proper resistance level and consequently testing the stability of that resistance level. The process of memristor forming using rectangular waves as input signals is considered. The influence of the amplitude, the polarization, the width, and the number of input pulses on the behavior of memristors is investigated. In particular, the effects of applying specific rectangular waveforms on the resistance of memristors is studied. Existing literature on memristor forming focuses on physical phenomena inside memristive elements during resistance switching process [8[...]

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