Search results for "solar [matter]"
showing 10 items of 1254 documents
Direct and inverse spin-orbit torques in antiferromagnetic and ferromagnetic FeRh/W(001)
2021
We use \textit{ab-initio} calculations to investigate spin-orbit torques (SOTs) in FeRh(001) deposited on W(100). Since FeRh undergoes a ferromagnetic-antiferromagnetic phase transition close to room temperature, we consider both phases of FeRh. In the antiferromagnetic case we find that the effective magnetic field of the even torque is staggered and therefore ideal to induce magnetization dynamics or to switch the antiferromagnet (AFM). At the antiferromagnetic resonance the inverse SOT induces a current density, which can be determined from the SOT. In the ferromagnetic case our calculations predict both even and odd components of the SOT, which can also be used to describe the ac and dc…
Anomalous low-temperature magnetoelastic properties of nanogranular (CoFeB)$_{x}$-(SiO$_{2}$)$_{1-x}$
2008
We report magnetostatic measurements for granulated films (CoFeB)$_{x}$-(SiO$_{2}$)$_{1-x}$ with fabrication induced intraplanar anisotropy. The measurements have been performed in the film plane in the wide temperature interval 4.5$��$300 K. They demonstrate that above films have low-temperature anomaly below the percolation threshold for conductivity. The essence of the above peculiarity is that below 100 K the temperature dependence of coercive field for magnetization along easy direction deviates strongly from Neel-Brown law. At temperature lowering, the sharp increase of coercivity is observed, accompanied by the appearance of coercive field for magnetization along hard direction in th…
Can fermion-boson stars reconcile multi-messenger observations of compact stars?
2021
Mixed fermion-boson stars are stable, horizonless, everywhere regular solutions of the coupled Einstein-(complex, massive) Klein-Gordon-Euler system. While isolated neutron stars and boson stars are uniquely determined by their central energy density, mixed configurations conform an extended parameter space that depends on the combination of the number of fermions and (ultra-light) bosons. The wider possibilities offered by fermion-boson stars could help explain the tension in the measurements of neutron star masses and radii reported in recent multi-messenger observations and nuclear-physics experiments. In this work we construct equilibrium configurations of mixed fermion-boson stars with…
Third-Generation Solar Cells: Concept, Materials and Performance - An Overview
2019
The large scarcity of natural fuels in earth crust has triggered to search alternative energy reservoirs for the future generation of human life. Because of large abundancy, solar energy is considered as big hope for the future generation energy utilization for commercial as well as home applications. The scientific revolution achieved in synthesis and processing of semiconductor nanomaterials, organic conducting polymers have led into new dimension in fabrication of future-generation solar cells. Reduction in the dimension of semiconductor nanomaterials significantly influences on their structural and optical properties which is helpful for the excellent photon harvesting. Also, their larg…
Effects of the Italian financial crisis on the photovoltaic dissemination in a southern city
2013
Abstract The aim of this paper is to estimate how the profitability of grid-connected PV (photovoltaic) systems may vary month by month due to the changes in all parameters involved in the economic evaluation (discount rate, PV electricity selling price, inflation rate, price of PV devices etc.). The effects of these variations were investigated for a district of a city in the South Italy (Palermo). The results of the analysis provided the trend of the actual coverage of the district power demand from June 2010 to August 2012. In particular the load match index, which considers the daily energy demand covered by PV systems, ranged from almost 30% to less than 12%, which is less than the val…
Review of potential and actual penetration of solar power in Vietnam
2020
With the average solar radiation reaching up to 5 kWh/m2, Vietnam is considered as a country showing an excellent potential for solar power production. Since the year 2000, there have been a lot of studies about the potential of this source in Vietnam. So far, many applications of solar power have been implemented on small, medium, and large scales. In fact, the total capacity of current grid-connected solar power plants has exceeded the planned capacity by 2020 nearly 6 times. However, the studies of solar potential in Vietnam are still incomplete. The policies and mechanisms for developing solar power projects have received attention from the authorities but have not been really satisfact…
The Recent Change in the Italian Policies for Photovoltaics: Effects on the Energy Demand Coverage of Grid-Connected PV Systems Installed in Urban Co…
2016
In July 2013, the Italian photovoltaic (PV) support policies changed the feed-in tariff (FIT) mechanism and turned to a tax credits program, which is currently in force. The aim of this paper is to investigate how such a radical change has influenced the electricity demand coverage of the PV systems installed in urban contexts. A methodology, which connects the economic assessment to a detailed architectural and energy suitability analysis, was applied to some case studies to analyse the relationships between the physical parameters related to multi-storey buildings (roof shapes, number of floors and area of flats) and the most relevant economic and financial features affecting the viabilit…
Power spectrum of turbulent convection in the solar photosphere
2020
The solar photosphere provides us with a laboratory for understanding turbulence in a layer where the fundamental processes of transport vary rapidly and a strongly superadiabatic region lies very closely to a subadiabatic layer. Our tools for probing the turbulence are high-resolution spectropolarimetric observations such as have recently been obtained with the two balloon-borne SUNRISE missions, and numerical simulations. Our aim is to study photospheric turbulence with the help of Fourier power spectra that we compute from observations and simulations. We also attempt to explain some properties of the photospheric overshooting flow with the help of its governing equations and simulations…
Impact of deep convection in the tropical tropopause layer in West Africa: in-situ observations and mesoscale modelling
2011
Abstract. We present the analysis of the impact of convection on the composition of the tropical tropopause layer region (TTL) in West-Africa during the AMMA-SCOUT campaign. Geophysica M55 aircraft observations of water vapor, ozone, aerosol and CO2 during August 2006 show perturbed values at altitudes ranging from 14 km to 17 km (above the main convective outflow) and satellite data indicates that air detrainment is likely to have originated from convective cloud east of the flights. Simulations of the BOLAM mesoscale model, nudged with infrared radiance temperatures, are used to estimate the convective impact in the upper troposphere and to assess the fraction of air processed by convecti…
Modeling of biomass smoke injection into the lower stratosphere by a large forest fire (Part I): reference simulation
2006
Abstract. Wildland fires in boreal regions have the potential to initiate deep convection, so-called pyro-convection, due to their release of sensible heat. Under favorable atmospheric conditions, large fires can result in pyro-convection that transports the emissions into the upper troposphere and the lower stratosphere. Here, we present three-dimensional model simulations of the injection of fire emissions into the lower stratosphere by pyro-convection. These model simulations are constrained and evaluated with observations obtained from the Chisholm fire in Alberta, Canada, in 2001. The active tracer high resolution atmospheric model (ATHAM) is initialized with observations obtained by r…