Nonlinear Mathematical Models of Metamaterials Defined as “Mass-in-Mass” and “Damper-in-Mass” Chains

To describe dynamic processes in an acoustic (mechanical) metamaterial, there are proposed models that are a one-dimensional chain containing the same masses connected by linearly elastic (or nonlinearly elastic) elements (springs) with the same stiffness. In this case, it is assumed that each mass contains inside itself a series connection of another mass and an elastic element or viscous element (damper).

Destressing MOSFETs by Series Connection in Low Gain Buck Converters

<p>Low-gain buck converters will enable low voltage loads to access high voltage DC sources by a single stage converter at very low duty cycles. SiC MOSFETs are still limited to 1.7kV commercially and by seriesing them with adequate gate driving strategy, high voltages can be switched. This paper proposes a driving circuit for series SiC MOSFETs to block higher voltages. The driving circuit provides negative off-state voltage and turn on/off transitions in less than 100ns. The low-gain buck converter performance is assessed when using a single IGBT switch and series SiC MOSFETs. A simulation is implemented and shows the superiority of the proposed driven series SiC MOSFETs with distributed voltage and thermal stresses.</p>

Destressing MOSFETs by Series Connection in Low Gain Buck Converters

<p>Low-gain buck converters will enable low voltage loads to access high voltage DC sources by a single stage converter at very low duty cycles. SiC MOSFETs are still limited to 1.7kV commercially and by seriesing them with adequate gate driving strategy, high voltages can be switched. This paper proposes a driving circuit for series SiC MOSFETs to block higher voltages. The driving circuit provides negative off-state voltage and turn on/off transitions in less than 100ns. The low-gain buck converter performance is assessed when using a single IGBT switch and series SiC MOSFETs. A simulation is implemented and shows the superiority of the proposed driven series SiC MOSFETs with distributed voltage and thermal stresses.</p>

Analysis of the Transformation of Random Signals and Noise Using Poly-Gaussian Models

Analysis performed transformation of random signals and noise in linear and nonlinear systems based on the use of poly-Gaussian models and multidimensional PDF of the output paths of information-measuring and radio systems. The classification of elements of these systems, as well as expressions describing the input action and output response of the system are given. It is shown that the analysis of information-measuring and systems can be carried out using poly-Gaussian models. The analysis is carried out with a series connection of a linear system and a nonlinear element, a series connection of a nonlinear element and a linear system, as well as with a parallel connection of the named links. The output response in all cases will be a mixture of a poly-Gaussian distribution with a number of components. An example of the analysis of signal transmission through an intermediate frequency amplifier and a linear detector against a background of non-Gaussian noise is given. The resulting probability density distribution of the sum of the signal and non-Gaussian noise at the output of the detector will be poly-Rice. The multidimensional probability distribution density of the output processes of the nonlinear signal envelope detector is also obtained. The results of modeling the found distribution densities are presented. It is shown that the use of the poly-Gaussian representation of signals and noise, as well as the impulse response of the system, makes it possible to effectively analyze inertial systems in the time domain.

Wireless Power Transfer Systems Optimization Using Multiple Magnetic Couplings

Multiple magnetic couplings used to increase the link distance in wireless power transfer systems (WPTSs) are not new. An efficient power transfer in conditions of an extended link distance requires a series connection of the intermediate coils. However, all four connections of the emitter and receiver coils are equally possible. This present paper conducts an extensive analysis of WPTSs utilizing three magnetic couplings. The type of connection of the emitter and receiver coils represented the criterion utilized for the WPTS optimization assessment. The first step requires the determination of the schematic of the sinusoidal equivalent circuit. Then, one synthesizes the functions describing the system performances (e.g., the amount of delivered active power or efficiency) by applying the entirely symbolic and or the hybrid symbolic-numerical formalism. The output of such functions consists of appropriate representation in the frequency domain, based upon Laplace state variable equations (SVE) or complex or Laplace modified nodal equations (MNE). The dependency of the WPTS performance on the number of magnetic couplings and their parameters included a study on resistive loss minimization. The minimization applies to the intermediate coils, whereas the outcomes are the active delivered power and the power transfer efficiency—the first study case aimed at a comparison between two distinct WPTSs: three magnetic couplings versus two. The second case of the study compared the WPTSs having a series connection of three magnetic couplings with those built with the emitter-receiver resonators in parallel. One determined the normalized sensitivities as frequency functions, which depend on circuit resistances, load resistance and the coupling factor between the second and the third coil. The optimization algorithms are suitable for computing optimal parameters of the given circuit to ensure maximum and minimum values of the performance value. Good simulation examples followed the proposed optimization techniques.

RESEARCH OF METHODS FOR DECREASE OF THE CAPACITANCE RATIO IN THE STW-RESONATORS

This paper presents the research of methods for decrease of the capacitance ratio in the STW-resonators without significant degradation of the quality factor by use of the external inductors and topology change: IDT division on parts and their series connection. The calculated and experimental data are presented for 416 MHz and 766 MHz STW-resonators with quality factors Q = 7000–7978. The capacitance ratio has been reduced from 1200 to 301.

Development of Foot Step Power Generation using Piezo Electric Sensors

This project was developed to need for a system that generates non conventional energy. Energy crisis is one of the major issues worldwide. This paper proposes maximum utilization of human locomotion energy for power generation using Piezo electric sensors. The basic principle was, any vibration or pressure that generate between surface and footsteps while walking, is converted into electric energy using Piezo electric transducers. A series connection of Piezo electric transducers are mounted on the tile and this tile is placed in the crowded area for the generation of electric energy. This paper explores the power generated by footsteps and used for mobile charging.