Search results for "Electricity"
showing 10 items of 1225 documents
Dielectric and Elastic Parameters of LixNa1-xTa0.1Nb0.9O3 Ferroelectric Solid Solution Ceramics
2011
Results of the studies of electric and elastic parameters as functions of concentration in ferroelectric LiхNa1-хTa0.1Nb0.9O3 (x = 0–0.16) solid solutions and comparative studies of the elastic properties by acoustic and contact probe techniques are reported. The electric and elastic properties of LiхNa1-хTa0.1Nb0.9O3 solid solutions are shown to be rather sensitive to structural distortion at concentration-induced structural phase transitions. The values of elastic modules obtained from acoustic measurements are found to be in good agreement with those obtained by contact probe techniques.
Adaptive Energy Management Strategy for Optimal Power Flow Control of Hybrid DC Microgrid
2020
In this work, an adaptive energy management strategy (AEMS) is proposed to achieve the optimal power flow control of off grid connected hybrid DC Microgrid (MG) against time varying source and load dynamics. The hybrid DC MG considered in this paper is operating with a solar PV array and mini hydro power plant (MHPP) as power dispatching sources. The intermittent input dynamics of solar PV system and time varying load power dynamics results in power fluctuations of hybrid DC MG. The MHPP cannot regulate these power fluctuations instantly due its operating dynamics. Therefore, AEMS has deployed a hybrid energy storage system (HESS) comprising battery and supercapacitor storage devices for co…
A Hybrid Energy Storage Sizing for a Vertical Take-off and Landing Electric Aircraft
2021
The energy storage sizing procedure for an all-electric aircraft, characterised by vertical take-off and landing (VTOL), is presented in the paper. In order to define the energy consumption, the propulsion system model has been developed and simulated, referring to a specific configuration of VOLT obtained by the transformation of a very light twin-propeller aircraft named Tecnam P2012 T. Specifically, a flight mission-oriented to air city taxing has been considered. The simulation results highlight the presence of significant peak power during take-off and landing. At the aim of optimising the weight and the volume of the energy storage systems (ESSs), considered a critical issue in all-el…
Hybrid Energy Storage for Underground Mining EV
2021
One of the main concerns when it comes to contributions to the carbon footprint is the consumption of fuel by vehicles, more specifically that of mining vehicles. One solution to this problem is replacing the combustion engine vehicles with electric vehicles. This also poses the problem of low power density. This paper proposes a solution of using supercapacitors and hybrid capacitors with the aim of investigating how they can affect the performance of electric vehicles. For this purpose, a background of fuel consumption and alternative solutions to the problem are discussed, a prototype was designed and built. It was found that when supercapacitors and hybrid capacitors were used in combin…
A Hybrid Storage Systems for All Electric Aircraft
2021
A hybrid energy storage system specifically designed for a fully electric aircraft is presented in the paper. The analysis of the time evolution of the power demand of the electric propulsion system during a test mission of Maxwell X-57, an all-electric aircraft developed by NASA, has pointed out the presence of significant peak power during take-off and air tack. Considered the issues related to weight and the volume of the energy storage systems (ESSs) in all-electric aircraft, a hybridization of aircraft ESS with a Supercapacitors (SCs) bank, devoted to smooth peak power demand, has been investigated. A comparison between the simulation results of an electrochemical battery and hybrid ES…
Power management of a battery/supercapacitor system for E-mobility applications
2019
Hybrid Energy Storage Systems (HESS) have been very popular in recent years in different applications, from electric vehicles (EVs) to smart grids and renewable energies, due to the growing need to accumulate electricity. The concept of hybridization arises from the requirement of both high energy and specific power. The battery/supercapacitor (SC) system offers great advantages in a DC bus, giving the opportunity to provide high amounts of power to the loads. In this paper, a system composed of two bidirectional DC-DC converters, one connected to a battery pack and one to a stack of supercapacitors, is presented for a DC bus in electrical mobility (E-Mobility) applications. The proposed co…
Thermal, electric and spin transport in superconductor/ferromagnetic-insulator structures
2019
A ferromagnetic insulator (FI) attached to a conventional superconductor (S) changes drastically the properties of the latter. Specifically, the exchange field at the FI/S interface leads to a splitting of the superconducting density of states. If S is a superconducting film, thinner than the superconducting coherence length, the modification of the density of states occurs over the whole sample. The co-existence of the exchange splitting and superconducting correlations in S/FI structures leads to striking transport phenomena that are of interest for applications in thermoelectricity, superconducting spintronics and radiation sensors. Here we review the most recent progress in understandin…
Atomistic Study of Surface Polarization in Superconducting Perovskites
1996
AbstractWe simulated the surface relaxation of the cubic perovskite paraelectric SrTiO3 crystal. The atomic positions in ten near-surface layers placed into the electrostatic field of the remainder of the crystal were calculated. Two-dimensional, periodic slab model was combined with the pair potentials treated in terms of the shell-model. Our calculations show that Ti+4, Sr+2 and O−2 ions shift differently from their crystal sites. This leads to a creation of a dipole moment near the surface which might give the paraelectric crystal the ferroelectric properties.
Impact of non-idealities on the conductance characteristics of superconductor-insulator-normal metal-insulator-superconductor tunnel junctions
2012
We have investigated the effect of asymmetry in tunnelling resistance of individual normal metal-insulator-superconductor (NIS) tunnel junctions that constitute a SINIS pair, both experimentally and theoretically. Ours results clearly demonstrate that any finite asymmetry in the tunnelling resistance gives rise to an excess current, as compared to its symmetric counterpart, both below and around the gap edge. The signature of this excess current is visible almost up to the critical temperature. We find that this apparent broadening of the density of states is purely electrical in origin. Our calculations also show that any finite resistance that is in series with the tunnelling resistance, …
Microrefrigeration by normal-metal/ insulator/superconductor tunnel junctions
1997
Abstract A normal-metal/insulator/superconductor (NIS) tunnel junction can be applied to cool electrons by biasing the junction suitably with external voltage. Because of the symmetry with bias voltage, two NIS junctions in series can form an efficient microrefrigerator. So far our SINIS microrefrigerator has been capable of reaching electronic temperatures of about 100 mK starting from 300 mK. To achieve appreciable refrigeration of the underlying lattice, microrefrigerator must be thermally decoupled from the bulk substrate. We have demonstrated experimentally the reduction of lattice temperature of a few mK at 200 mK by extending the normal electrode on a thin dielectric membrane. Method…