Search results for "Radiance"
showing 10 items of 284 documents
Modelling spatial and spectral systematic noise patterns on CHRIS/PROBA hyperspectral data
2006
In addition to typical random noise, remote sensing hyperspectral images are generally affected by non-periodic partially deterministic disturbance patterns due to the image formation process and characterized by a high degree of spatial and spectral coherence. This paper presents a new technique that faces the problem of removing the spatial coherent noise known as vertical stripping (VS) usually found in images acquired by push-broom sensors, in particular for the Compact High Resolution Imaging Spectrometer (CHRIS). The correction is based on the hypothesis that the vertical disturbance presents higher spatial frequencies than the surface radiance. The proposed method introduces a way to…
Effect of the relative optical air mass and the clearness index on solar erythemal UV irradiance
2014
This paper analyses the effects of the clearness index (Kt) and the relative optical air mass (mr) on erythemal UV irradiance (UVER). The UVER measurements were made in Valencia (Spain) from 6:00 am to 6:00 pm between June 2003 and December 2012 and (140,000 data points). Firstly, two models were used to calculate values for the erythemal ultraviolet irradiance clearness index (KtUVER) as a function of the global irradiance clearness index (Kt). Secondly, a potential regression model to measure the KtUVER as a function of the relative optical air mass was studied. The coefficients of this regression were evaluated for clear and cloudy days, as well as for days with high and low ozone levels…
A Morphological Clustering Method for daily solar radiation curves
2011
Abstract We present a new method based on Mathematical Morphology techniques for the classification of solar radiation curves that we call MfCM. The main advantage of using MfCM as opposed to daily clearness index distributions is that it allows us to keep the dynamics of the solar radiance curves in the analysis: both cloud transitions and variability in direct radiation are simultaneously taken into account. To illustrate our proposal, we use a set of real radiation data collected in a location sited in southern Spain.
Analysis of spectral irradiance distribution for PV applications at high latitude
2020
The spectral distribution of global tilted irradiance measured in Grimstad, Norway, is analyzed in terms of the average photon energy ( $APE$ ) blue fraction ( $BF$ ) and useful fraction ( $UF$ ). The results based on eight months of recorded data show a general shift of the $APE,\ BF$ , and $UF$ values to higher values than reference AM1.5G spectrum, with 1.63 eV, 0.45, and 0.88 being the average indices, respectively. The statistical coefficient of variation ( $CV$ ) is used to determine the variation of indices. The $CV$ for $APE,\ BF$ , and $UF$ are calculated to be 20.1%, 26.1%, and 25.7%, respectively confirming the earlier findings on $APE$ being a more accurate index for the quantif…
Machine Learning-Based View Synthesis in Fourier Lightfield Microscopy
2022
Current interest in Fourier lightfield microscopy is increasing, due to its ability to acquire 3D images of thick dynamic samples. This technique is based on simultaneously capturing, in a single shot, and with a monocular setup, a number of orthographic perspective views of 3D microscopic samples. An essential feature of Fourier lightfield microscopy is that the number of acquired views is low, due to the trade-off relationship existing between the number of views and their corresponding lateral resolution. Therefore, it is important to have a tool for the generation of a high number of synthesized view images, without compromising their lateral resolution. In this context we investigate h…
Test of the European Joint Research Centre performance model for c-Si PV modules
2012
The performance of ten c-Si PV modules is studied at different levels of illumination and module temperatures and is modeled in terms of relative efficiency with respect to Standard Testing Conditions (STC). A recently proposed model is tested in Nordic conditions for generic mono- and mc-Si devices with screen-printed cells as well as for some high-efficiency cell designs. Two of the modules are field aged. Averaged model coefficients are derived and compared to values found in the literature. Irradiance and module temperatures measured in 2011 are then used to estimate the expected annual energy yields. The measured yields equal the predicted ones within 1.6% (mean bias error −1.0%) which…
A physical model for interpreting the land surface temperature obtained by remote sensors over incomplete canopies
1992
Abstract At the present moment, land surface temperature cannot be obtained in a routine way from satellite data due, in part, to the nonexistence of a complete theoretical model that permits us to know the physical significance of land surface temperature obtained by remote sensors. In this article a relationship between the effective temperature of the radiative system vegetation-ground and the temperatures of each part of the system (top, sunny and shaded wall of vegetation, and sunny and shaded soil) has been derived. It depends on the proportions of each component observed by the sensor, on the ground and vegetation emissivities, and on the crop structure (mean height, width, and spaci…
Growth and survival of European whitefish larvae under enhanced UV-B irradiance
2004
Two laboratory rearing experiments with newly hatched European whitefish Coregonus lavaretus larvae were performed to study the effects of UV-B (280–315 nm) radiation on their survival and growth. The results indicate that under normal circumstances in Finnish lakes, enhanced UV irradiance will not be a threat to the survival of newly hatched European whitefish larvae.
Experimental characterization of Ruthenium-based Dye Sensitized Solar Cells and study of light-soaking effect impact on performance
2016
In this paper, we present an experimental investigation on the performance of Ruthenium-based Dye Sensitized Solar Cells (DSSCs) at different irradiance levels, incident wavelengths and hours of illumination. In particular, the measurements have been aimed at studying the performance variation due to light soaking effect since this phenomenon has noteworthy practical implications, such as stability tests of DSSCs. Our results show that the short circuit current density, the open circuit voltage and the conversion efficiency η increase with the hours of light soaking. Finally, the observed phenomenon is reversible, and thus the performance decreases again when the cell is kept in the dark.
Characterization of laser ablation of copper in the irradiance regime of laser-induced breakdown spectroscopy analysis
2014
Abstract The LIBS signal depends both on the ablated mass and on the plasma excitation temperature. These fundamental parameters depend in a complex manner on laser ablation and on laser–plasma coupling. As several works in the literature suggest that laser ablation processes play a predominant role compared to plasma heating phenomena in the LIBS signal variations, this paper focuses on the study of laser ablation. The objective was to determine an interaction regime enabling to maximally control the laser ablation. Nanosecond laser ablation of copper at 266 nm was characterized by scanning electron microscopy and optical profilometry analysis, in air at 1 bar and in the vacuum. The laser …