Search results for "solar [matter]"
showing 10 items of 1254 documents
Pitch controller modeling for wind turbine power regulation using feed forward control strategies
2015
In this work, pitch controlled power regulation of a horizontal axis wind turbine coupled with a fixed speed asynchronous generator is studied using SimulationX®. Wind turbines need to be operated as per specified power output vs wind speed characteristics of it. If the wind speed is between the cut-in wind speed and the rated wind speed, then the wind turbine needs to be operated constant Cp. If wind speed is between the rated speed and the cut-off wind speed, then the wind turbine needs to be operated for constant rated power. To extract rated power above rated wind speed a proper controller strategy is required. This work provides a simulation model for power regulation of a horizontal a…
A novel solar trigeneration system integrating PVT (photovoltaic/thermal collectors) and SW (seawater) desalination: Dynamic simulation and economic …
2014
Abstract The paper investigates the integration of renewable energy sources and water systems, presenting a novel solar system producing simultaneously: electrical energy, thermal energy, cooling energy and domestic water. Such system is designed for small communities in European Mediterranean countries, rich in renewable sources and poor in fossil fuels and water resources. The polygeneration system under analysis includes PVT (photovoltaic/thermal solar collectors), a MED (multi-effect distillation) system for SW (seawater) desalination, a single-stage LiBr–H2O ACH (absorption chiller) and additional components, such as storage tanks, AHs (auxiliary heaters) and BOP (balance of plant) dev…
Dynamics photovoltaic generators: Technical aspects and economical valuation
2010
The strategy adopted from many European nations and not, to entrust the electric energy production to differently energetic sources has determined an increment of the scientific research for the solar resource exploitation. These scientific community activities follows with attention from the entrepreneurial world have concentrated on the innovative techniques and methodologies of the source conversion, solar concentration and the direction's device optimization. This job focuses its attention on the simple application of solar-track device, based on consolidated technologies. The diffused application of these dispositive, could be, shortly, an important increment of electricity generation …
Low-amplitude variations detected by CoRoT in the B8IIIe star HD 175 869
2009
Context.The origin of the short-term variability in Be stars remains a matter of controversy. Pulsations and rotational modulation are the components of the favored hypothesis.Aims.We present our analysis of CoRoT data of the B8IIIe star HD 175869 observed during the first short run in the center direction (SRC1).Methods.We review both the instrumental effects visible in the CoRoT light curve and the analysis methods used by the CoRoT Be team. We applied these methods to the CoRoT light curve of the star HD 175869. A search for line-profile variations in the spectroscopic data was also performed. We also searched for a magnetic field, by applying the LSD technique to spectropolarimetric dat…
The Application of Different Model of Multi-Layer Perceptrons in the Estimation of Wind Speed
2012
Wind speed forecasting is essential for effective planning of wind energy exploitation projects. The ability to predict short-term wind speed is a prerequisite for all the operators of the wind energy sector. Consequently it is essential to identify an efficient method for forecasts. In this paper, the wind speed in the province of Trapani (Sicily) is modeled by artificial neural network. Several model of neural network were generated and compared through error measures. Simulation results show that the estimated values of wind speed are in good agreement with the values measured by anemometers..
Young, active radio stars in the AB Doradus moving group
2017
Context. Precise determination of stellar masses is necessary to test the validity of pre-main-sequence (PMS) stellar evolutionary models, whose predictions are in disagreement with measurements for masses below 1.2 M. To improve such a test, and based on our previous studies, we selected the AB Doradus moving group (AB Dor-MG) as the best-suited association on which to apply radio-based high-precision astrometric techniques to study binary systems. Aims. We seek to determine precise estimates of the masses of a set of stars belonging to the AB Dor-MG using radio and infrared observations. Methods. We observed in phase-reference mode with the Very Large Array (VLA) at 5 GHz and with the Eur…
Magnetic field dynamos and magnetically triggered flow instabilities
2017
The project A2 of the LIMTECH Alliance aimed at a better understanding of those magnetohydrodynamic instabilities that are relevant for the generation and the action of cosmic magnetic fields. These comprise the hydromagnetic dynamo effect and various magnetically triggered flow instabilities, such as the magnetorotational instability and the Tayler instability. The project was intended to support the experimental capabilities to become available in the framework of the DREsden Sodium facility for DYNamo and thermohydraulic studies (DRESDYN). An associated starting grant was focused on the dimensioning of a liquid metal experiment on the newly found magnetic destabilization of rotating flow…
Probing the physics of the solar atmosphere with the Multi-slit Solar Explorer (MUSE): I. Coronal Heating
2022
The Multi-slit Solar Explorer (MUSE) is a proposed NASA MIDEX mission, currently in Phase A, composed of a multi-slit EUV spectrograph (in three narrow spectral bands centered around 171A, 284A, and 108A) and an EUV context imager (in two narrow passbands around 195A and 304A). MUSE will provide unprecedented spectral and imaging diagnostics of the solar corona at high spatial (<0.5 arcsec), and temporal resolution (down to ~0.5s) thanks to its innovative multi-slit design. By obtaining spectra in 4 bright EUV lines (Fe IX 171A , Fe XV 284A, Fe XIX-Fe XXI 108A) covering a wide range of transition region and coronal temperatures along 37 slits simultaneously, MUSE will for the first time …
Modelling of asymmetric nanojets in coronal loops
2021
Context. Observations of reconnection jets in the solar corona are emerging as a possible diagnostic for studying highly elusive coronal heating. Such jets, and in particular those termed nanojets, can be observed in coronal loops and have been linked to nanoflares. However, while models successfully describe the bilateral post-reconnection magnetic slingshot effect that leads to the jets, observations reveal that nanojets are unidirectional or highly asymmetric, with only the jet travelling inward with respect to the coronal loop’s curvature being clearly observed. Aims. The aim of this work is to address the role of the curvature of the coronal loop in the generation and evolution of asym…
RotNet: Fast and Scalable Estimation of Stellar Rotation Periods Using Convolutional Neural Networks
2020
Magnetic activity in stars manifests as dark spots on their surfaces that modulate the brightness observed by telescopes. These light curves contain important information on stellar rotation. However, the accurate estimation of rotation periods is computationally expensive due to scarce ground truth information, noisy data, and large parameter spaces that lead to degenerate solutions. We harness the power of deep learning and successfully apply Convolutional Neural Networks to regress stellar rotation periods from Kepler light curves. Geometry-preserving time-series to image transformations of the light curves serve as inputs to a ResNet-18 based architecture which is trained through transf…