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The activation propagation characteristics obtained when using homogeneous monodomain model (MM) of the cardiac ventricles and the model based on cellular automaton (CA) are compared in this study. The MM comprises the reaction — diffusion equation of the propagation and the modified FitzHugh-Nagumo equations of the electrical excitation of cardiac cells. This model was simulated in Comsol Multiphysics...
In this paper we introduce an extension of the self-temperature-sensing of stress compensated (SC) quartz resonator based on simultaneous excitation of two overtones (3rd and 5th overtone) - the slow thickness-shear modes (i.e. the c modes) in dual-mode crystal oscillator (DMXO). The extension is based on implementation of a self-identification of the differences between aging rates (long-term frequency...
Heart rate variability (HRV) analysis provides noninvasive way for assessment of neural activity that control cardiovascular system. Contributions of sympathetic and parasympathetic autonomous nervous system that modulate instantaneous heart rate are studied by means of spectral analysis. The objective is to recover modulating signal spectrum from beat occurrence times. In this paper, properties of...
In this paper, the dependence of radio-frequency (RF) field absorption on human body dimensions is investigated. The resonance properties of an ellipsoidal homogeneous human model have been investigated in frequency range from 10 MHz to 500 MHz with assistance of CST Microwave Studio program environment. In the article, the simulation of RF field absorption in the ellipsoidal body model has been performed...
This paper deals with evaluation of self-temperature-sensing of stress compensated (SC) quartz resonator with simultaneous excitation of two higher overtones - the slow thickness-shear modes (i.e. the c-modes) in dual-mode crystal oscillator (DMXO). Two different combinations of overtones simultaneously excited in the standard 10-MHz 3rd overtone SC-cut resonator are compared here: - the 5th overtone...
This article is devoted to an investigation of electrophysical parameters of biological tissue influence on its absorption of microwave energy. The specific absorption rate (SAR) is the dosimetric quantity for evaluation of microwave energy absorbed in biological tissue. Many parameters have effect on the SAR value, such as geometry of the part of the body, which is exposed to microwave energy, electrical...
The influence of radio-frequency (RF) field orientation on specific absorption rate (SAR) in a human body is investigated in this paper. Three basic field orientations have been simulated: electric field vector, magnetic field vector and Poynting vector parallel to the longitudinal axis of a human body. The influence has been investigated in frequency range from 10 MHz to 2450 MHz with assistance...
The paper deals with a crystal oscillator with differential amplifier based on bipolar junction transistors. The main attention is devoted to the influence of loss resistance of the used piezoelectric resonator to the gain at the corresponding open feedback loop. The derived relation for this gain corresponds with relevant results obtained by means of computer simulations.
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