Search results for "Capacitor"
showing 10 items of 164 documents
Dielectric properties and partial discharge endurance of polypropylene-silica nanocomposite
2010
This paper presents the results of the dielectric properties and partial discharge endurance measurements conducted on polypropylene (PP)-silica nanocomposite. The material compounds were analyzed with micro-Raman spectroscopy, X-ray tomography and transmission electron microscopy (TEM). ac and dc breakdown strength of the materials was measured. Dielectric response, capacitance and loss factor of the film samples were measured as a function of temperature and frequency. Partial discharge (PD) endurance of the reference PP and PP Silica nanocomposite was studied as a function of ac voltage. Material surfaces were analyzed after PD stress with optical microscopy. All dielectric measurements …
Electrical analogous in viscoelasticity
2014
In this paper, electrical analogous models of fractional hereditary materials are introduced. Based on recent works by the authors, mechanical models of materials viscoelasticity behavior are firstly approached by using fractional mathematical operators. Viscoelastic models have elastic and viscous components which are obtained by combining springs and dashpots. Various arrangements of these elements can be used, and all of these viscoelastic models can be equivalently modeled as electrical circuits, where the spring and dashpot are analogous to the capacitance and resistance, respectively. The proposed models are validated by using modal analysis. Moreover, a comparison with numerical expe…
A simple approach towards one-dimensional mesoporous carbon with superior electrochemical capacitive activity.
2009
One-dimensional (1D) mesoporous carbons with highly ordered 3D interconnected pore structure and large-diameter pore size (10–20 nm) have been synthesized by a simple precursor-controlled thermolysis approach; such unique carbonaceous frameworks show superior capacitive behavior in electrochemical double-layer capacitors.
A hybrid storage system for wireless sensor nodes powered with energy harvesting
2019
With the recent development of Internet of Things (IoT) and Wireless Sensor Networks (WSN), research and industry have been increasingly focusing on the opportumty of collecting the energy arising from the environment. The Energy Harvesting provides the possibility to supply devices which are placed out of reach or in hazardous spots, e.g. the Wireless Sensor Nodes. Among the different parts belonging to an Energy Harvesting system, the power management network represents a challenging topic. In this paper a Hybrid Energy Storage System (HESS) usable for a WSN powered with Energy Harvesting, based on a battery-capacitor integration, is presented. The experimental results concerning the asse…
Power dispatching techniques as a finite state machine for a standalone photovoltaic system with a hybrid energy storage
2020
Standalone photovoltaic system (SPVS) is usually embedded with an energy storage unit to overcome the intermittency of photovoltaic (PV) generation as well as to address load variations in off-grid operation. In SPVS energy systems, batteries can serve as the long term energy storage and contributing to the large portion of the energy demand but to overcome the load intermittency, it necessitates a fast response energy storage embedded with the battery as a hybrid energy storage (HES) for dynamic loads (e.g., Electric Vehicle loads, emergency power management). In this work, Lead-Acid (LA) battery and supper capacitor (SC) array are used as the HES. HES helps not only in increasing more uti…
Design of a Battery/Ultracapacitor Energy Storage System for Electric Vehicle Applications
2018
The battery/ultracapacitors (UCs) integration is able to provide notable advantages in the power management of an electric vehicle (EV), in terms of capability of both high energy storage and readiness to deal with fast load variations. In order to manage the charge (or discharge) of the UCs from (or towards) a DC voltage bus, a proper bi-directional converter is required. In this paper, a bi-directional DC-DC converter in connection with a stack of UCs is described and some power simulation results are provided. The proposed converter is a B2R (buck-boost regulator) type. The load is represented by a 40kW peak power, kept for a time window of 3s, as required by the Worldwide harmonized Lig…
Modeling Information Processing Using Nonidentical Coulomb Blockade Nanostructures
2017
In recent years, molecular-protected metallic nanoparticles (NPs) have attracted a great deal of attention. Because of their reduced size, they behave like tiny capacitors so that there is an energy penalty when adding an electron to the NP which suppresses the electric current at a potential lower than a threshold value. This phenomenon is known as Coulomb blockade (CB) and allows the transport of electrons to be modulated through an external gate provided that the energy penalty is higher than the thermal energy. Together with the possibility of tailoring their properties, molecular protected NPs are potential candidates as future components of high density, low consumption electronics. H…
Note: Direct sensor resistance-to-frequency conversion with generalized impedance converter.
2010
In this note a squared output signal is generated from an astable circuit. Its frequency has a linear dependence on the resistance value of a resistive temperature sensor. The main circuit to obtain this direct relationship is the generalized impedance converter configured as a capacitor controlled by a sensor resistance. The proposed measurement method allows a direct analog-to-digital interface of information involved in resistive sensors. The converter finds applications in portable low voltage and low power design of instrumentation electronic systems.
CFRP STRUCTURAL CAPACITORS: EFFECT OF DAMAGE AND MECHANICAL LOAD ON CAPACITANCE
2013
Aim of this work is to study the effect of mechanical load and damages, on the performance of structural capacitors, made by CFRP composite laminates with a PET dielectric film (treated with sodium hydroxide) inserted at the laminate middle-plane. Such capacitors have been characterized by ILSS and tensile tests and the properties so estimated were compared to those of the simple CFRP. By measuring the capacitance before mechanical loading, under loading and after unloading, it has been observed that, due to the damage of the CFRP layers, proved also by proper fractographic analysis, at high strain level the capacitance decreases although it exhibits a complete recovery after unloading. Suc…
The Effect of Anodizing Bath Composition on the Electronic Properties of Anodic Ta-Nb Mixed Oxides
2022
Anodic oxides were grown to 50 V on Ta-Nb sputtering deposited alloys, with high Nb content, in acetate ions containing an aqueous solution to study the effect of the anodizing bath composition on anodic layers’ dielectric properties. Photoelectrochemical measurements proved the presence of a photocurrent in the band gap of photon energy lower than oxides, due to optical transitions involving localized electronic states as a consequence of acetate ions incorporation. Flat band potential value estimates assessed the insulating nature of the anodic oxides grown in the acetate buffer solution. Differential capacitance measurements showed that the highest capacitance value was measured for the …