1,721,613 research outputs found
Riflessioni sulla risk disclosure. Risultati della ricerca realizzata dal forum governance EY
No full textAn alternative tool for the energy evaluation and the management of thermal networks: The exergy analysis
No full textIn the context of the strategy 'Europe 2020', European Directive 2012/27 identifies the high efficiency cogeneration and the district heating and cooling as instruments to reach the energy efficiency goals. The great potential deriving from these solutions is basically linked to the possible use of Renewable Energy Sources (RES) rarely used in centralized energy production. In literature many energy, economic or environmental indexes for the evaluation of energy networks efficiency are available. Notwithstanding, these indexes, based on primary energy savings, are less reliable when generation system powered by RES are analyzed. The goal of this work is the introduction of exergy as an alternative evaluation tool for the characterization of the thermal energy networks efficiency. In this research a parametric analysis has been carried out based on a Simulink [1] model. This model simulates the dynamic behavior of an energy micro-grid dedicated to three different buildings. The simulations have been run for three cities located in different climatic zones. Results show the positive impact of exergy as a tool to evaluate energy networks powered by traditional and renewable energy sources. © 2016 IEEE
Study and Comparison of Control and Regulation Systems for Solar Thermal Plants
No full textSolar thermal systems are mainly used for the application of small size in the residential market, with the purpose of producing domestic hot water and, in applications that allow, covering part of heating requirements. This technology is increasingly used in other fields of application through the adoption of largest size systems that are more complicated than residential systems and require a detailed and careful design. Among the different phases of design, there is the study of the best system of management and control; this research aims to develop a help for designers during this choice. The first step of this work has been a commercial search in order to determine the current modes of control of solar thermal systems. After, were made some dynamic simulations using some of the control mode previously defined. The simulations were done with Matlab-Simulink simulation software using a stable and calibrated dynamic model. Simulink is a graphical interface that uses different types of elements (blocks) that allow creating models to simulate a dynamic system; that is, a system that can be represented by a model of differential equations or difference where the independent variable is time. Finally, the control modes were tested in a building energy retrofit. © 2016 The Authors
The Simons Observatory: modeling optical systematics in the Large Aperture Telescope
No full textWe present geometrical and physical optics simulation results for the Simons Observatory Large Aperture Telescope. This work was developed as part of the general design process for the telescope; allowing us to evaluate the impact of various design choices on performance metrics and potential systematic effects. The primary goal of the simulations was to evaluate the final design of the reflectors and the cold optics which are now being built. We describe non-sequential ray tracing used to inform the design of the cold optics, including absorbers internal to each optics tube. We discuss ray tracing simulations of the telescope structure that allow us to determine geometries that minimize detector loading and mitigate spurious near-field effects that have not been resolved by the internal baffling. We also describe physical optics simulations, performed over a range of frequencies and field locations, that produce estimates of monochromatic far field beam patterns which in turn are used to gauge general optical performance. Finally, we describe simulations that shed light on beam sidelobes from panel gap diffraction
A measurement of the degree scale CMB B-mode angular power spectrum with POLARBEAR
No full textWe present a measurement of the -mode polarization power spectrum of the cosmic microwave background (CMB) using taken from July 2014 to December 2016 with the POLARBEAR experiment. The CMB power spectra are measured using observations at 150 GHz with an instantaneous array sensitivity of on a 670 square degree patch of sky centered at (RA, Dec)=(). A continuously rotating half-wave plate is used to modulate polarization and to suppress low-frequency noise. We achieve - effective polarization map noise with a knee in sensitivity of , where the inflationary gravitational wave signal is expected to peak. The measured -mode power spectrum is consistent with a CDM lensing and single dust component foreground model over a range of multipoles . The data disfavor zero at using this range of POLARBEAR data alone. We cross-correlate our data with Planck high frequency maps and find the low- -mode power in the combined dataset to be consistent with thermal dust emission. We place an upper limit on the tensor-to-scalar ratio r < 0.90 at 95% confidence level after marginalizing over foregrounds
Development of an advanced simulation model for solar cooling plants
No full textSolar Cooling systems represent an effective solution to increase the use of solar energy in buildings, satisfying cooling demand in a sustainable and efficient way. Although the reference technologies are mature (solar collectors, absorption chillers, adsorption chillers, etc.), these systems often require detailed studies to define control techniques, management integration systems and energy optimization [1,2]. This work has been focused on the development and calibration of a dynamic simulation model of a solar cooling system in order to create an efficient and robust tool to support the phases of planning and management. The model was developed in Matlab-Simulink ambient taking as a reference the system installed at the building F-51 of ENEA Research Center "Casaccia" in Rome. The calibration carried out made the model representative of reality with an average error of 10% and it has allowed us to quantify the benefits obtained by some optimization measures in order to make the maximum primary energy savings in the overall operation of the system. The simulation model can help to increase the commercial deployment of solar cooling systems when used to identify the layout of plant and the associated control strategies that maximize the system's efficiency and profitability of the investment. © 2015 The Authors
Inpainting galactic foreground intensity and polarization maps using convolutional neural network
No full textDeep convolutional neural networks have been a popular tool for image generation and restoration. The performance of these networks is related to the capability of learning realistic features from a large dataset. In this work, we applied the problem of inpainting non-Gaussian signal, in the context of Galactic diffuse emissions at the millimetric and sub-millimetric regimes, specifically Synchrotron and Thermal Dust emission. Both of them are affected by contamination at small angular scales due to extra-galactic radio sources (the former) and to dusty star-forming galaxies (the latter). We consider the performances of a nearest-neighbors inpainting technique and compare it with two novels methodologies relying on generative Neural Networks. We show that the generative network is able to reproduce the statistical properties of the ground truth signal more consistently with high confidence level. The Python Inpainter for Cosmological and AStrophysical SOurces (PICASSO) is a package encoding a suite of inpainting methods described i n this work and has been made publicly available
Survey-based analysis of the electrical energy demand in Italian households
No full textAccording to Eurostat statistics, electrical energy covered 17.5% of the final energy consumptions in Italian households in 2015, and the electrical intensity increase of 8.9% from 2000 to 2015. ISTAT survey on energy consumption of households represents a valuable source of data for an extensive analysis of this topic. In order to evaluate these data, a model has been implemented in Matlab®, which calculates the electrical energy demand for lighting, electrical appliances, cooking appliances, DHW boilers, space heating and cooling. The present paper describes the methodology and the main results obtained with the above ISTAT dataset, consisting of 20,000 records. The numerical model allows allocating the electrical energy consumption for each end-use, in order to obtain a reliable estimation of the households' habits. Furthermore, it provides a useful tool applicable to the next surveys, in order to analyse the evolution of the electrical consumption of Italian households, to evaluate the potential energy savings of specific retrofit measures and to provide recommendations for policy actions supporting the improvement of the energy efficiency in the residential sector. © 2018, Mathematical Modelling of Engineering Problems
A mechanism of transformational plasticity
No full textIn order to understand the phenomenon of reversible plasticity exhibited by shape memoryalloys and other smart materials, we study an elementary prototypical model. Building on anoriginal idea of M ̈uller and Villaggio [17], we consider an inhomogeneous ensemble of bi-stableelements connected in series and loaded in a soft device. To interpret the fine structure of thehysteresis loops observed experimentally, we assume that the dynamics is maximally dissipativeand investigate different evolutionary strategies for a “driven” system with external forcechanging quasi-statically. Our main result is that the inhomogeneity of the elastic propertiesleads to a distinctive hardening with serrations of a Portevin-Le Chatelier type and producesa realistic memory structure characterized by the “congruency” and “return point memory”propertie
A Robust Approach for Crop Misalignment Estimation in Single and Double JPEG Compressed Images
No full textIn forensics investigation, information about the crop performed after a JPEG compression can be useful exploited to reconstruct the manipulation history of the analyzed images and localize forgeries. Statistics computed from AC histograms, obtained performing an additional JPEG compression with a set of constant quantization matrices, are exploited to design a robust and effective algorithm to retrieve information about the employed crop. Finally, the effectiveness of the proposed solution has been demonstrated through a series of tests conducted considering different patch sizes, quantization matrices, and comparisons with a state-of-the-art solution in single and double JPEG compression scenario
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