Centrum senzorických, informačních a komunikačních systémů

Browse

Recent Submissions

Now showing 1 - 5 of 33
  • Thumbnail Image
    Item
    Voltammetry as a Tool for Characterization of CdTe Quantum Dots
    (MDPI, 2013-06-27) Adam, Pavlína; Vaculovičová, Markéta; Hubálek, Jaromír; Adam, Vojtěch; Kizek, René
    Electrochemical detection of quantum dots (QDs) has already been used in numerous applications. However, QDs have not been well characterized using voltammetry, with respect to their characterization and quantification. Therefore, the main aim was to characterize CdTe QDs using cyclic and differential pulse voltammetry. The obtained peaks were identified and the detection limit (3 S/N) was estimated down to 100 fg/mL. Based on the convincing results, a new method for how to study stability and quantify the dots was suggested. Thus, the approach was further utilized for the testing of QDs stability
  • Thumbnail Image
    Item
    An electronically tunable current-mode quadrature oscillator using PCAs
    (Taylor & Francis, 2012-04-10) Herencsár, Norbert; Lahiri, Abhirup; Vrba, Kamil; Koton, Jaroslav
    The paper presents a new realization of active RC sinusoidal oscillator with electronically tunable condition and frequency of oscillation. As compared to the class of three resistors, two capacitors (3R-2C) based canonic oscillators, the proposed circuit here uses only two resistors and two capacitors as the passive components and still provides non-interactive tuning laws for the condition of oscillation (CO) and the frequency of oscillation (FO). The proposed circuit employs new bipolar programmable current amplifier (PCA) as the active building block and is capable of simultaneously providing two explicit quadrature current outputs. SPICE simulation results have been included to verify the workability of the circuit as an oscillator and the tuning range of the FO.
  • Thumbnail Image
    Item
    Lagrangian for circuits with higher-order elements
    (MDPI, 2019-10-29) Biolek, Zdeněk; Biolek, Dalibor; Biolková, Viera
    The necessary and sufficient conditions of the validity of Hamilton’s variational principle for circuits consisting of (alpha,beta) elements from Chua’s periodical table are derived. It is shown that the principle holds if and only if all the circuit elements lie on the so-called -diagonal with a constant sum of the indices alpha and beta. In this case, the Lagrangian is the sum of the state functions of elements of the L or +R types minus the sum of the state functions of elements of the C or -R types. The equations of motion generated by this Lagrangian are always of even-order. If all elements are linear, the equations of motion contain only even-order derivatives of the independent variable. Conclusions are illustrated on an example of the synthesis of the Pais-Uhlenbeck oscillator via the elements from Chua’s table.
  • Thumbnail Image
    Item
    Higher-Order Hamiltonian for Circuits with (alpha,beta) Elements
    (MDPI AG, 2020-04-05) Biolek, Zdeněk; Biolek, Dalibor; Biolková, Viera; Kolka, Zdeněk
    The paper studies the construction of the Hamiltonian for circuits built from the (alpha,beta) elements of Chua’s periodic table. It starts from the Lagrange function, whose existence is limited to sigma-circuits, i.e., circuits built exclusively from elements located on a common sigma-diagonal of the table. We show that the Hamiltonian can also be constructed via the generalized Tellegen’s theorem. According to the ideas of predictive modeling, the resulting Hamiltonian is made up exclusively of the constitutive relations of the elements in the circuit. Within the frame of Ostrogradsky’s formalism, the simulation scheme of S-circuits is designed and examined with the example of a nonlinear Pais–Uhlenbeck oscillator.
  • Thumbnail Image
    Item
    Duality of Complex Systems Built from Higher-Order Elements
    (Hindawi, 2018-09-07) Biolek, Dalibor; Biolek, Zdeněk; Biolková, Viera
    The duality of nonlinear systems built from higher-order two-terminal Chua’s elements and independent voltage and current sources is analyzed. Two different approaches are now being generalized for circuits with higher-order elements: the classical duality principle, hitherto restricted to circuits built from R-C-L elements, and Chua’s duality of memristive circuits. The so-called storeyed structure of fundamental elements is used as an integrating platform of both approaches. It is shown that the combination of associated flip-type and shift-type transformations of the circuit elements can generate dual networks with interesting features. The regularities of the duality can be used for modeling, hardware emulation or synthesis of systems built from elements that are not commonly available, such as memristors, via classical dual elements.