Designing a tuned-shunt electrodynamic metamaterial in the presence of uncertainties

Resonant structural vibrations are a common source of disruptive noise, and suppressing these vibrations is often the most direct way to reduce the noise levels. Elastic metamaterials (EMMs) consist of distributed resonant substructures, at a scale which is small compared to the wavelength of vibration. This allows these materials to be used in applications where space is limited, and more traditional vibration suppression techniques would be impractical. Tuned resonators can be designed through selection of geometry or material properties, but an alternative approach, which requires significantly less prototyping, is through the use of shunted electrodynamic inertial actuators. In this paper, a novel electrodynamic metamaterial (EDMM) is proposed consisting of an array of mass-produced inertial actuators, each connected to a tuned shunt impedance. It is considered impractical to measure the dynamic and electrical parameters of a large number of actuators, and so the effect of uncertainties in the actuators is investigated on both the performance and the stability of the EDMM.

Design and Simulation of Extended Interaction Cavities for a Ka band Multi beam Klystron

This article reports about the design approach, electromagnetic simulation and analysis results of high-frequency ladder-type input, output, and intermediate RF cavaties for Ka-band multi-beam extended interaction klystron. Several parameters of the cavity, such as quality factor, shunt impedance, etc., have been investigated by the assistance of electromagnetic software CST microwave studio.

Guidelines for the layout and tuning of piezoelectric resonant shunt with negative capacitances in terms of dynamic compliance, mobility and accelerance

This paper addresses the vibration attenuation provided by the resonant piezoelectric shunt enhanced by means of negative capacitances. The shunt impedance is composed by one or two negative capacitances, a resistance and an inductance. It is shown that closed analytical formulations, common to all the possible connections of the negative capacitances, can be derived for the tuning of the circuit components and for the prediction of the attenuation in terms of dynamic compliance, mobility and accelerance. The paper also compares the attenuation performance provided by the two possible layouts for the electrical link between the resistance and the inductance, that are series and parallel. Furthermore, this work evidences which shunt configurations offer advantages in terms of practical implementation and the benefits provided by the use of negative capacitances in the shunt circuit. In the last part of the paper, guidelines for the use of resonant shunt are given to the reader and, finally, the theoretical results are validated by means of an experimental campaign showing that it is possible to cancel the resonance on which the resonant shunt is targeted.

AC characteristics of low-ohmic foil shunts influenced by eddy currents in the mounting body

The requirements for precision current-sensing shunts are getting more sophisticated due to further development of fast switch-mode converters and other high-frequency applications. Good AC characteristics are important both for industrial applications and for calibration standard purposes. Low-ohmic foil shunts show excellent DC behavior, but the AC characteristics could be improved. The optimization of foil shunts towards better temperature independency and load stability in the range of a few parts per million per kelvin can lead to significant weaker AC performance. In this work, eddy currents in the mounting body are identified as a cause of the increasing real part of the shunt impedance at higher frequencies by means of a numerical field simulation.

Voltage Slump Compensation using Facts Controllers on Power System

This article dispense the different FACTS controllers integrated circuits using a simulation program that emphasis with PSPICE. The FACTS controller controls series impedance, shunt impedance, voltage, current and phase angle. In this paper, a simplified circuit model of Series Compensator and Unified Power Quality conditioner has been analyzed and the simulation results coincides with the theoretical results..

Piezoelectric resonant shunt enhancement by negative capacitances: Optimisation, performance and resonance cancellation

This article addresses piezoelectric shunt damping through a resonant shunt associated with negative capacitances. The main objective of this article is to provide guidelines for choosing the best electrical circuit layout in terms of control performance and possible stability issues. This article proposes general analytical formulations for the tuning/optimisation of the electrical shunt impedance and for the prediction of the attenuation performance. These formulations are demonstrated to be valid for all the possible configurations of the negative capacitances. It is demonstrated that the behaviour of the different shunt circuits can indeed be described by a common mathematical treatment. Moreover, the use of two negative capacitances together is shown to provide benefits compared to traditional layouts based on a single negative capacitance. The mentioned advantages relate to both stability and attenuation performance. The use of a resonant shunt with the addition of negative capacitances is finally proven to provide enough attenuation to even cancel eigenfrequency peaks in some cases. This article also analyses the main issues arising from the practical implementation of the negative capacitances. Finally, the theoretical results are validated through experiments conducted on a cantilever beam coupled to two piezoelectric patches.