1,300 research outputs found
A model proposal for the electric energy valorization in a pv power plant equipped with CAES system
In this article, an analytical method is evaluated and implemented; to assess the possible electricity sales strate-gies produced by a 3 MW photovoltaic power plant, connected to a 250 kW CAES (Compressed Air Energy Storage) system, with a storage capacity of 750 kWh. The presented model combines a different numbers of parameters and variables, relevant for the system optimization. Several simulations of various system configu-rations have been carried out, to explore and evaluate the economic and technical feasibility of the plant, spe-cifically it has been valued tow case of study: CASE 1 the system is not incentive; CASE 2 the system is incen-tive. In the end of paper it has been rated the Leveled Cost of Energy (LCOE) and specified how the investment could become affordable in the foreseeable future
Green practices and financial performance: A global outlook
Companies around the world adopt green practices with the aim to reduce their environmental impacts and improve their financial performance. The present study theorizes about and empirically examines the impacts of corporate green practices on financial performance. Indexes of pollution prevention, green supply management, green product development and ISO 14001 adoption are obtained for each firm in a panel of 3490 publicly-traded companies from 58 countries over 13 years. Results show that internal green practices (pollution prevention and green supply chain management) are the major environmental drivers of financial performance, while external green practices (green product development) play a secondary role in determining financial performance. The adoption of ISO 14001 appears to have a negative impact on financial performance. This study provides empirical support for policy-makers promoting environmental practices that may lead to sustainable economic growth
Solar radiation forecasting, accounting for daily variability
Radiation forecast accounting for daily and instantaneous variability was pursued by means of a new bi-parametric statistical model that builds on a model previously proposed by the same authors. The statistical model is developed with direct reference to the Liu-Jordan clear sky theoretical expression but is not bound by a specific clear sky model; it accounts separately for the mean daily variability and for the variation of solar irradiance during the day by means of two corrective parameters. This new proposal allows for a better understanding of the physical phenomena and improves the effectiveness of statistical characterization and subsequent simulation of the introduced parameters to generate a synthetic solar irradiance time series. Furthermore, the analysis of the experimental distributions of the two parameters’ data was developed, obtaining opportune fittings by means of parametric analytical distributions or mixtures of more than one distribution. Finally, the model was further improved toward the inclusion of weather prediction information in the solar irradiance forecasting stage, from the perspective of overcoming the limitations of purely statistical approaches and implementing a new tool in the frame of solar irradiance prediction accounting for weather predictions over different time horizons
On the use of asymmetric PSF on NIR images of crowded stellar fields
We present data collected using the camera PISCES coupled with the Firt Light
Adaptive Optics (FLAO) mounted at the Large Binocular Telescope (LBT). The
images were collected using two natural guide stars with an apparent magnitude
of R<13 mag. During these observations the seeing was on average ~0.9". The AO
performed very well: the images display a mean FWHM of 0.05 arcsec and of 0.06
arcsec in the J- and in the Ks-band, respectively. The Strehl ratio on the
quoted images reaches 13-30% (J) and 50-65% (Ks), in the off and in the central
pointings respectively. On the basis of this sample we have reached a J-band
limiting magnitude of ~22.5 mag and the deepest Ks-band limiting magnitude ever
obtained in a crowded stellar field: Ks~23 mag.
J-band images display a complex change in the shape of the PSF when moving at
larger radial distances from the natural guide star. In particular, the stellar
images become more elongated in approaching the corners of the J-band images
whereas the Ks-band images are more uniform. We discuss in detail the strategy
used to perform accurate and deep photometry in these very challenging images.
In particular we will focus our attention on the use of an updated version of
ROMAFOT based on asymmetric and analytical Point Spread Functions.
The quality of the photometry allowed us to properly identify a feature that
clearly shows up in NIR bands: the main sequence knee (MSK). The MSK is
independent of the evolutionary age, therefore the difference in magnitude with
the canonical clock to constrain the cluster age, the main sequence turn off
(MSTO), provides an estimate of the absolute age of the cluster. The key
advantage of this new approach is that the error decreases by a factor of two
when compared with the classical one. Combining ground-based Ks with space
F606W photometry, we estimate the absolute age of M15 to be 13.70+-0.80 Gyr.Comment: 15 pages, 7 figures, presented at the SPIE conference 201
The Italian Validation of the Gender Minority Stress and Resilience Measure
Transgender and gender nonconforming (TGNC) people experience high levels of minority stress and associated risk for negative mental health outcomes. Notwithstanding, TGNC people may resist the negative effects of minority stress on health through the resilience factors. As no comprehensive measures of gender minority stress and resilience exist in Italy, this study evaluated the psychometric characteristics of an Italian language version of the Gender and Minority Stress and Resilience Measure (GMSR) in an Italian sample of 203 TGNC individuals ranged from 18 to 66 years of age (M = 30.70, SD = 10.79). The GMSR, developed in the United States in 2015, assesses distal stressors (discrimination, rejection, victimization, and nonaffirmation), proximal stressors (internalized transphobia, negative expectations, and nondisclosure), and resilience factors (pride and community connectedness). Confirmatory factor analysis showed that the original 9-factor model had adequate fit to the data obtained from the Italian sample. Criterion validity was partially confirmed, as the stress scales positively correlated with anxiety and depression, and pride negatively correlated with depression, but not anxiety. On the contrary, community connectedness did not correlate with any of the mental health measures. Instead, both convergent and discriminant validity were confirmed as both distal and proximal stressors positively correlated with perceived stress, community connectedness was positively associated with perceived support from friends, and all correlations were below .60. This study offers evidence of the reliability and validity of the GMSR in the Italian context, providing Italian clinicians and researchers with a comprehensive tool to assess gender minority stress in TGNC individuals
Major discrepancies between what clinical trial registries record and paediatric randomised controlled trials publish
Background: Whether information from clinical trial registries (CTRs) and published randomised controlled trial (RCTs) differs remains unknown. Knowing more about discrepancies should alert those who rely on RCTs for medical decision-making to possible dissemination or reporting bias. To provide help in critically appraising research relevant for clinical practice we sought possible discrepancies between what CTRs record and paediatric RCTs actually publish. For this purpose, after identifying six reporting domains including funding, design, and outcomes, we collected data from 20 consecutive RCTs published in a widely read peer-reviewed paediatric journal and cross-checked reported features with those in the corresponding CTRs. Methods: We collected data for 20 unselected, consecutive paediatric RCTs published in a widely read peer-reviewed journal from July to November 2013. To assess discrepancies, two reviewers identified and scored six reporting domains: funding and conflict of interests; sample size, inclusion and exclusion criteria or crossover; primary and secondary outcomes, early study completion, and main outcome reporting. After applying the Critical Appraisal Skills Programme (CASP) checklist, five reviewer pairs cross-checked CTRs and matching RCTs, then mapped and coded the reporting domains and scored combined discrepancy as low, medium and high. Results: The 20 RCTs were registered in five different CTRs. Even though the 20 RCTs fulfilled the CASP general criteria for assessing internal validity, 19 clinical trials had medium or high combined discrepancy scores for what the 20 RCTs reported and the matched five CTRs stated. All 20 RCTs selectively reported or failed to report main outcomes, 9 had discrepancies in declaring sponsorship, 8 discrepancies in the sample size, 9 failed to respect inclusion or exclusion criteria, 11 downgraded or modified primary outcome or upgraded secondary outcomes, and 13 completed early without justification. The CTRs for seven trials failed to index automatically the URL address or the RCT reference, and for 12 recorded RCT details, but the authors failed to report the results. Conclusions: Major discrepancies between what CTRs record and paediatric RCTs publish raise concern about what clinical trials conclude. Our findings should make clinicians, who rely on RCT results for medical decision-making, aware of dissemination or reporting bias. Trialists need to bring CTR data and reported protocols into line with published data
Ultra-deep Large Binocular Camera U-band Imaging of the GOODS-North Field: Depth vs. Resolution
We present a study of the trade-off between depth and resolution using a
large number of U-band imaging observations in the GOODS-North field
(Giavalisco et al. 2004) from the Large Binocular Camera (LBC) on the Large
Binocular Telescope (LBT). Having acquired over 30 hours of data (315 images
with 5-6 mins exposures), we generated multiple image mosaics, starting with
the best atmospheric seeing images (FWHM 0.8"), which constitute
10% of the total data set. For subsequent mosaics, we added in data with
larger seeing values until the final, deepest mosaic included all images with
FWHM 1.8" (94% of the total data set). From the mosaics, we
made object catalogs to compare the optimal-resolution, yet shallower image to
the lower-resolution but deeper image. We show that the number counts for both
images are 90% complete to . Fainter than
27, the object counts from the optimal-resolution image start to
drop-off dramatically (90% between = 27 and 28 mag), while the deepest
image with better surface-brightness sensitivity ( 32
mag arcsec) show a more gradual drop (10% between 27
and 28 mag). For the brightest galaxies within the GOODS-N field, structure and
clumpy features within the galaxies are more prominent in the
optimal-resolution image compared to the deeper mosaics. Finally, we find - for
220 brighter galaxies with 24 mag - only marginal
differences in total flux between the optimal-resolution and lower-resolution
light-profiles to 32 mag arcsec. In only 10% of
the cases are the total-flux differences larger than 0.5 mag. This helps
constrain how much flux can be missed from galaxy outskirts, which is important
for studies of the Extragalactic Background Light.Comment: 24 pages, 14 figures, submitted to PASP, comments welcom
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