Search results for "Electricity"

Efficient Peltier refrigeration by a pair of normal metal/ insulator/superconductor junctions

1995

We suggest and demonstrate in experiment that two normal metal /insulator/ superconductor (NIS) tunnel junctions combined in series to form a symmetric SINIS structure can operate as an efficient Peltier refrigerator. Specifically, it is shown that the SINIS structure with normal-state junction resistances 1.0 and 1.1 k$\Omega$ is capable of reaching a temperature of about 100 mK starting from 300 mK. We estimate the corresponding cooling power to be 1.5 pW per total junction area of 0.8 $\mu$m$^2$ at $T= 300$ mK.

Refrigeration of a dielectric membrane by superconductor/insulator/normalmetal/insulator/superconductor tunneling

1997

We have applied tunneling of electrons between a normal metal and a superconductor to refrigerate a thin dielectric membrane attached to the normal electrode of a superconductor/ insulator/normal-metal/insulator/superconductor (SINIS) structure. Starting from T≈200 mK, a decrease in temperature of several mK was observed, measured by a separate thermometer on the membrane. It should be straightforward to improve the refrigerator performance to the level of the recently demonstrated SINIS electron cooling method, such that the drop in the lattice temperature would be more than an order of magnitude larger.

NIS chip refrigeration

1999

A normal-metal/insulator/superconductor (NIS) tunnel junction can be applied to cool electrons by biasing the junction suitably with external voltage. Two NIS junctions in series can form an efficient microrefrigerator because of the symmetry with bias voltage. 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, the microrefrigerator must be thermally decoupled from the bulk substrate. We have demonstrated experimentally the reduction of lattice temperature by 23 mK at 180 mK by extending the normal electrode on a thin dielectric membrane with four suspended bri…

Optical Symmetry of Ferroelectric Liquid Crystal Cells

1990

We observe an exact optical symmetry in Surface Stabilized Ferroelectric Liquid Crystal (SSFLC) cells in polarized transmission optical microscopy and spectroscopy. A theoretical argument based on the intrinsic time reversibility of Maxwell's equations and energy conservation is developed to explain this symmetry. The results support the model of Clark and Rieker for zig-zag wall structure and illustrate the necessity of including the orientational binding of the director at the chevron interface.

Surface Relaxation in Ferroelectric Perovskites: An Atomistic Study

1996

ABSTRACTThe effect of the [001] surface relaxation on the polarization of the paraelectric BaTiO3 is simulated in the framework of the shell model. Our atomistic simulations show a large polarization of ions in the first several layers nearby the surface and confirm the possibility of co-existence of Ti-and Ba-terminated [001] BaTiO3 surfaces which have very close surface energies.

New frontiers in sustainable energy production and storage

2015

Evidently, one of the most effective ways to reduce CO2 emissions consists in the deployment of renewable energies, with the advantage of securing and expanding the energy supplies of a given country. The main problem that arises is due to the intermittent temporary character of many renewable resources like solar and wind. For this reason, it has been recently concluded that in case of high integration of renewables into the distribution grid (more than about 30% of the electricity mix), the implementation of energy storage systems together with smart grids is necessary. Therefore, renewable energies for large scale power production in country would usually require the availability of a su…

Sustainable and cost-efficient energy supply and utilisation through innovative concepts and technologies at regional, urban and single-user scales

2019

Abstract The environmental impact of the energy sector and the security and economics of energy supply and utilisation have been raising increasing concerns, stimulating the search for innovative solutions for a sustainable use of resources. This article provides an overview of published research in this area, with a focus on papers contributed in special issues of leading journals dedicated to the series of Conferences on Sustainable Development of Energy, Water and Environment Systems (SDEWES), including the articles in the current special issue. Based on this review, research trends are identified and achievements supporting the energy transition are highlighted. The studies that focused…

Fast electroclinic switching in a ferroelectric LC-polysiloxane

1992

Reversible effect of MR and ELF magnetic fields (0.5 T and 0.5 mT) on human lymphocyte activation patterns.

2006

Purpose: The aim of this study was to investigate the effects of magnetic fields (MF) of different intensity generated by a magnetic resonance (MR) unit (0.5 Tesla) and a double cylindrical coil (0.5 mTesla) on human CD4+ T cell lines. Materials and methods: CD4+ T cells were exposed for two hours under isothermal conditions (37 ± 0.5°C) to the above mentioned MF; a control group was provided for each exposed sample. After exposure, the samples were analysed in the laboratory for the following endpoints: Release of cytokines, expression of surface markers, cell proliferation and levels of cytosolic free-calcium. Results: Exposure to MF for 2 h and subsequent in vitro stimulation in the pres…

Observation of intrinsically bright terrestrial gamma ray flashes from the Mediterranean basin

2015

Abstract  We present three terrestrial gamma ray flashes (TGFs) observed over the Mediterranean basin by the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) satellite. Since the occurrence of these events in the Mediterranean region is quite rare, the characterization of the events was optimized by combining different approaches in order to better define the cloud of origin. The TGFs on 7 November 2004 and 16 October 2006 came from clouds with cloud top higher than 10–12 km where often a strong penetration into the stratosphere is found. This kind of cloud is usually associated with heavy precipitation and intense lightning activity. Nevertheless, the analysis of the cloud type…