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Sedimentary microbial fuel cells are promising harvesting systems generating powers as low as 10 μW, which is sufficient for powering underwater environmental sensors. This paper proposes a methodology and modeling to design a flyback converter in discontinuous conduction mode harvesting powers as low as 10th of μWs to maximize the harvested energy and boost its voltage to a minimum value required...
Non-hyperbolic points of slow-fast systems (also known as singularly perturbed ordinary differential equations) are responsible for many interesting behavior such as relaxation oscillations, canards, mixed-mode oscillations, etc. Recently, the authors have proposed a control strategy to stabilize non-hyperbolic points of planar slow-fast systems. Such strategy is based on geometric desingularization,...
The XXI century companies are increasingly interested on in the development of complex processes on bioengineering and health sciences. In this context, it is essential for undergraduate and graduate students to understand the behavior of complex phenomena. However, nowadays, academic programs are limited to the study of linear systems and first-order approximations; while companies use sophisticated...
In this paper, a new model based on piecewise linear (PWL) functions is proposed and analyzed by considering the well known Pernarowski's mathematical model for an isolated beta cell. Contrary to Pernarowski's model, we replace the original cubic functions with PWL functions with multi-segments in order to obtain bursting electrical activity (BEA) of beta cell. The number of segments depends on the...
In magnetic tunnel junctions specifically designed to be super-paramagnetic (S-MTJs), thermal noise induces stochastic switching between the parallel and anti-parallel states (Figure 1) [1]. As a consequence, they behave like stochastic oscillators, oscillating with non-constant period but with a well-defined average frequency. Although such junctions cannot be used for conventional memory applications,...
This paper proposes a memristor SPICE model using tukey window (or tapered cosine window) function. Compared with the proposed tukey window function and the previously boundary function, the proposed method is resistant to numerical errors. From the SPICE simulation result of relaxation oscillator, we find that the proposed model can be reduced the effect of round-off errors.
Pathophysiologic neural synchronization is a sign of several neurological disorders such as parkinson and epilepsy. In addition, based on established neurophysiologic findings, astrocytes (more type of glial cells) regulate dynamically the synaptic transmission and have key roles in stabilizing neural synchronization. Therefore, in the present study, a new model for digital astrocyte-inspired stimulator...
Due to the measurement techniques developed, it is now possible to observe signals at different levels in neural structures. These observations give rise to increasing works dealing with setting up the relation between such signals and cognitive processes, neurodegenerative diseases and neurobehavioral disorders. Computational neuroscience is becoming more influential in investigating the mechanisms...
It is well known that theoretical analysis based on the mathematical predictive models of middle-sized genetic regulatory networks are crucial to understand the life at system level for systems biology. Since there doesn't exist an efficient mathematical model for the middle-sized or large-sized biological systems, it is also a challenge to theoretically investigate these networks. To overcome the...
This work sheds some light into the crucial discussion over which memristor model should be adopted in the design of memristor-based electronic circuits. In a first study, taking the Pickett's model as reference, for a documented circuit and input setting some of the most acknowledged memristor models are fitted to it by means of an optimization procedure. The second study shows how the dynamics of...
Autonomic oscillatory activities exist in almost every living thing and most of them are produced by rhythmic activities of the corresponding neural system. This paper proposes a neural oscillator based on the control of a Schmitt Trigger. The oscillator implements 3 neuron cells and 4 synapse circuits, and integrates them into a compact neural network with a source neuron driving two oscillating...
Computing parametric sensitivities for oscillators has a now well-understood subtlety associated with the indeterminacy of phase. A less universal, but still vexing, subtlety arises when an oscillator is described by a system of differential equations with “hidden” conservation constraints (HCC's); defined as weighted sums of state variables that are time-invariant. If there are HCC's, as is commonly...
The logical formalism is a convenient framework to qualitatively model regulatory networks for which detailed quantitative information is barely available. In this discrete framework, network behaviours are usually represented by means of state transition graphs. However, as network sizes increase, state transition graphs often become too large to be effectively constructed, let alone analysed.
Researchers are now developing synthetic genetic circuits to manipulate the biochemical processes within living cells. In order to model and predict the behavior of these circuits, the designer must account for numerous reactions among many chemical species and genetic components. The analysis of genetic circuits is complicated by the fact that small molecule counts and sporadic gene expression makes...
The multifractional process is introduced as a natural extension of traditional monofractional process. The selling point of multifractional process is that its Hölder regularity is allowed to vary from point to point, such that makes it a promising model for those stochastic processes whose regularity evolves in time. A new wavelet-based algorithm to synthesize a realization of multifractional process...
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