A nonlinear piezoelectric shunt absorber with 2:1 internal resonance: experimental proof of concept

An experimental proof of concept of a new semi-passive nonlinear piezoelectric shunt absorber, introduced theoretically in a companion article, is presented in this work. This absorber is obtained by connecting, through a piezoelectric transducer, an elastic structure to a resonant circuit that includes a quadratic nonlinearity. This nonlinearity is obtained by including in the circuit a voltage source proportional to the square of the voltage across the piezoelectric transducer, thanks to an analog multiplier circuit. Then, by tuning the electric resonance of the circuit to half the value of one of the resonances of the elastic structure, a two-to-one internal resonance is at hand. As a result, a strong energy transfer occurs from the mechanical mode to be attenuated to the electrical mode of the shunt, leading to two essential features: a nonlinear antiresonance in place of the mechanical resonance and an amplitude saturation. Namely, the amplitude of the elastic structure oscillations at the antiresonance becomes, above a given threshold, independent of the forcing level, contrary to a classical linear resonant shunt. This paper presents the experimental setup, the designed nonlinear shunt circuit and the main experimental results.

Recent Advances in Perylene Diimide-Based Active Materials in Electrical Mode Gas Sensing

This review provides an update on advances in the area of electrical mode sensors using organic small molecule n-type semiconductors based on perylene. Among small organic molecules, perylene diimides (PDIs) are an important class of materials due to their outstanding thermal, chemical, electronic, and optical properties, all of which make them promising candidates for a wide range of organic electronic devices including sensors, organic solar cells, organic field-effect transistors, and organic light-emitting diodes. This is mainly due to their electron-withdrawing nature and significant charge transfer properties. Perylene-based sensors of this type show high sensing performance towards various analytes, particularly reducing gases like ammonia and hydrazine, but there are several issues that need to be addressed including the selectivity towards a specific gas, the effect of relative humidity, and operating temperature. In this review, we focus on the strategies and design principles applied to the gas-sensing performance of PDI-based devices, including resistive sensors, amperometric sensors, and operating at room temperature. The device properties and sensing mechanisms for different analytes, focusing on hydrazine and ammonia, are studied in detail, and some future research perspectives are discussed for this promising field. We hope the discussed results and examples inspire new forms of molecular engineering and begin to open opportunities for other rylene diimide classes to be applied as active materials.

The Comparative Analysis of Modern Electric Modes Control Systems in Electric Arc and Ladle Furnaces

The research presents the comparative analysis of the most common electrical mode control systems for electric arc furnaces (EAF) and ladle furnaces (LF) produced by the leading foreign companies, i.e. Siemens VAI (Primetals Technologies), Danieli, Amec Spie , AMI, Ferrotron. The comparative analysis criteria are the functionality requirements for the electric mode control systems, which ensure optimal operation of the furnace units at minimum production costs. Such analysis allows solving various tasks related to the electric steel-making production planning, as well as to basic technological equipment supplier selection. The results of the comparative analysis are of significant practical importance, since in a number of cases, the studies into the furnace units’ operation optimization show no technical possibility to achieve the required energy and time levels due to the limitations posed by the architecture of the electrical mode and the electrode motion control system.

Spectrometer-Free Graphene Plasmonics Based Refractive Index Sensor

We propose a spectrometer-free refractive index sensor based on a graphene plasmonic structure. The spectrometer-free feature of the device is realized thanks to the dynamic tunability of graphene’s chemical potential, through electrostatic biasing. The proposed sensor exhibits a 1566 nm/RIU sensitivity, a 250.6 RIU−1 figure of merit in the optical mode of operation and a 713.2 meV/RIU sensitivity, a 246.8 RIU−1 figure of merit in the electrical mode of operation. This performance outlines the optimized operation of this spectrometer-free sensor that simplifies its design and can bring terahertz sensing one step closer to its practical realization, with promising applications in biosensing and/or gas sensing.

Simulating of charge build-up in irradiated MOS/SOI transistors

The charge build-up in the interface of silicon / buried oxide in n-channel MOS/SOI transistors depending on their geometric parameters and electrical modes during ionizing irradiation is calculated with the use of the software Silvaco. It is shown that the electrical mode is most “harsh”, when during irradiation the voltage of +5 V is applied to drain and source electrodes and 0 V is applied to substrate, gate and channel feeding. The amount of the built-up charge can be substantially reduced by applying a negative bias to the substrate and by decreasing the thickness of the buried oxide layer.