1,700 research outputs found

    On the potential of using fractional-order systems to model the respiratory impedance

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    This contribution provides an analysis of the human respiratory system in frequency domain by means of estimating the respiratory impedance. Further on, analysis of several models for human respiratory impedance is done, leading to the conclusion that a fractional model gives a better description of the impedance than the classical theory of integer-order systems. A mathematical analysis follows, starting from the conclusions obtained heuristically. Correlation to the physiological characteristics of the respiratory system is discussed

    Evolutionary Synthesis of Fractional Capacitor Using Simulated Annealing Method

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    Synthesis of fractional capacitor using classical analog circuit synthesis method was described in [6]. The work presented in this paper is focused on synthesis of the same problem by means of evolutionary method simulated annealing. Based on given desired characteristic function as input impedance or transfer function, the proposed method is able to synthesize topology and values of the components of the desired analog circuit. Comparison of the results given in [6] and results obtained by the proposed method will be given and discussed

    Numerical synthesis of filtering antennas

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    Dizertační práce je zaměřena na kompletní metodiku návrhu tří a čtyř prvkových flíčkových anténních řad, které neobsahují žádné filtrující části a přesto se chovají jako filtrující antény (filtény). Návrhová metodika kombinuje přístup pro návrh filtrů s přístupem pro anténní řady a zahrnuje tvarování frekvenčních odezev činitele odrazu a normovaného realizovaného zisku. Směr hlavního laloku přes pracovní pásmo je kontrolován také. S cílem kontrolovat tvary uvedených charakteristik, nové gi koeficienty jsou představeny pro návrh filtrujících anténních řad. Návrhová metodika byla ověřena na tří a čtyř prvkové filtrující anténní řadě přes frekvenční pásmo od 4,8 GHz do 6,8 GHz, pro šířku pásma celé struktury od 7 % do 14 % a pro požadovanou úroveň činitele odrazu od –10 dB do –20 dB. Celá metodika byla podpořena výrobou a měřením šesti testovacích vzorků filtrujících anténních řad s rozdílnými konfiguracemi. Ve všech případech se simulované a naměřené výsledky dobře shodují.The dissertation thesis is focused on a complete design methodology of a three and four-element patch antenna arrays which are without any filtering parts and yet behave like a filtering antenna (filtenna). This design combines filter and antenna approaches and includes shaping the frequency response of the reflection coefficient and the modelling of the frequency response of the normalized realized gain. The frequency response of the main lobe direction is controlled as well. In order to control the shape of these responses, a set of gi coefficients for designing the filtering antenna array are obtained. The design methodology was verified on the three-element and four-element filtennas over the frequency range from 4.8 GHz to 6.8 GHz; for fractional bandwidth from 7 % to 14 % and for level of the reflection coefficient from –10 dB to –20 dB. The whole design methodology was supported by manufacturing and measuring six test cases of the filtering antenna array with different configurations. Simulated and measured results show a good agreement in all cases.

    Filtenna Integration Achieving Ideal Chebyshev Return Losses

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    This paper demonstrates that it is possible to find an ideal filter response (Chebyshew, Butterworth,..) considering the antenna as the last resonator of a filter under certain circumstances related with the antenna performance and the bandwidth of the filtenna device. If these circumstances are not accomplished, we can achieve excellent performance as well, by means of an iterative process the goal of which is defined by either a filter mask or a classical filter function itself. The methodology is based on the conventional coupling matrix technique for filter design and has been validated by fabricating a microstrip prototype using hairpin resonators and a rectangular patch antenna

    Synchronization of Nonlinear Circuits in Dynamic Electrical Networks with General Topologies

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    Sufficient conditions are derived for global asymptotic synchronization in a system of identical nonlinear electrical circuits coupled through linear time-invariant (LTI) electrical networks. In particular, the conditions we derive apply to settings where: i) the nonlinear circuits are composed of a parallel combination of passive LTI circuit elements and a nonlinear voltage-dependent current source with finite gain; and ii) a collection of these circuits are coupled through either uniform or homogeneous LTI electrical networks. Uniform electrical networks have identical per-unit-length impedances. Homogeneous electrical networks are characterized by having the same effective impedance between any two terminals with the others open circuited. Synchronization in these networks is guaranteed by ensuring the stability of an equivalent coordinate-transformed differential system that emphasizes signal differences. The applicability of the synchronization conditions to this broad class of networks follows from leveraging recent results on structural and spectral properties of Kron reduction---a model-reduction procedure that isolates the interactions of the nonlinear circuits in the network. The validity of the analytical results is demonstrated with simulations in networks of coupled Chua's circuits

    Evolutionary Synthesis of Analog Electronic Circuits Using EDA Algorithms

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    Disertační práce je zaměřena na návrh analogových elektronických obvodů pomocí algoritmů s pravěpodobnostními modely (algoritmy EDA). Prezentované metody jsou na základě požadovaných charakteristik cílových obvodů schopny navrhnout jak parametry použitých komponent tak také jejich topologii zapojení. Tři různé metody využití EDA algoritmů jsou navrženy a otestovány na příkladech skutečných problémů z oblasti analogových elektronických obvodů. První metoda je určena pro návrh pasivních analogových obvodů a využívá algoritmus UMDA pro návrh jak topologie zapojení tak také hodnot parametrů použitých komponent. Metoda je použita pro návrh admitanční sítě s požadovanou vstupní impedancí pro účely chaotického oscilátoru. Druhá metoda je také určena pro návrh pasivních analogových obvodů a využívá hybridní přístup - UMDA pro návrh topologie a metodu lokální optimalizace pro návrh parametrů komponent. Třetí metoda umožňuje návrh analogových obvodů obsahujících také tranzistory. Metoda využívá hybridní přístup - EDA algoritmus pro syntézu topologie a metoda lokální optimalizace pro určení parametrů použitých komponent. Informace o topologii je v jednotlivých jedincích populace vyjádřena pomocí grafů a hypergrafů.Dissertation thesis is focused on design of analog electronic circuits using Estimation of Distribution Algorithms (EDA). Based on the desired characteristics of the target circuits the proposed methods are able to design the parameters of the used components and theirs topology of connection as well. Three different methods employing EDA algorithms are proposed and verified on examples of real problems from the area of analog circuits design. The first method is capable to design passive analog circuits. The method employs UMDA algorithm which is used for determination of the parameters of the used components and synthesis of the topology of their connection as well. The method is verified on the problem of design of admittance network with desired input impedance function which is used as a part of chaotic oscillator circuit. The second method is also capable to design passive analog circuits. The method employs hybrid approach - UMDA for synthesis of the topology and local optimization method for determination of the parameters of the components. The third method is capable to design analog circuits which include also ac- tive components such as transistors. Hybrid approach is used. The topology is synthesized using EDA algorithm and the parameters are determined using a local optimization method. In the individuals of the population information about the topology is represented using graphs and hypergraphs.

    Numerical Simulation of Parallel RLC Model Using Different Fractional Derivative Operators

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    In the current study, the theory of fractional calculus is applied to the electric parallel RLC circuit. The aim of this article is to alter the concept of a parallel RLC circuit by applying various fractional derivative operators. A fractional RLC circuit was investigated via Caputo, Caputo-Fabrizio, and Atangana-Baleanu derivatives. The Laplace transform technique was applied to resolve the system of governing differential equations. The results for the various orders are compared to each other. When the fractional order derivative tends to be one, the system\u27s performance is found to be very slow due to a decrease in damping capacity. The results for the various orders are compared to each other. When the fractional order derivative tends to be one, the system\u27s performance is found to be very slow due to a decrease in damping capacity. The results for the various orders are compared to each other. When the fractional order derivative tends to be one, the system\u27s performance is found to be very slow due to a decrease in damping capacity
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