2,767 research outputs found

    Metodologie innovative per il supporto alla progettazione e all’analisi delle prestazioni di impianti ad energia solare a concentrazione ed eolici off-shore utilizzando immagini satellitari ottiche e SAR

    Get PDF
    In questo lavoro presentiamo delle nuove metodologie, sviluppate nell’ambito del progetto SATENERG (Servizi sATellitari per le ENergie Rinnovabili di nuova Generazione) finanziato dall’Agenzia Spaziale Italiana, sia per il supporto alla progettazione/pianificazione che per il monitoraggio quasi in tempo reale e l’analisi delle prestazioni degli impianti ad energia rinnovabile di nuova generazione (CSP, CPV ed eolici off-shore) utilizzando immagini satellitari. In particolare per quanto riguarda gli impianti solari a concentrazione (CSP e CPV), abbiamo sviluppato un metodo per ricavare l’irradianza solare incidente al suolo (in particolare la sua componente diretta normale rispetto ai raggi solari, fondamentale per questo tipo di impianti) da immagini ottiche satellitari. Ciò, unito ad un modello di funzionamento di tali impianti e degli inverter, ci ha resi in grado di poter sviluppare un servizio di supporto nella progettazione e pianificazione di nuove costruzioni di impianti CSP e CPV (analizzando serie storiche di dati satellitari) ed anche un servizio di monitoraggio e analisi delle prestazioni per quelli già esistenti (usando invece immagini satellitari quasi in tempo reale). In maniera simile, usando immagini SAR (Synthetic Aperture Radar), abbiamo sviluppato un metodo per ricavare l’intensità e la direzione del vento in aree marine da remoto che ci ha permesso, utilizzando anche un modello di impianto eolico off-shore (turbina e inverter), di sviluppare sia un servizio di supporto alla progettazione/pianificazione che un servizio di monitoraggio quasi in tempo reale della produzione di un impianto eolico off-shore. Le prime applicazioni di queste nuove metodologie hanno già portato ad avere ottimi risultati in vari casi di prova sia per quanto concerne il monitoraggio dell’irradianza diretta su piano normale, in cui l’irradianza misurata e quella ricavata da dato satellitare non si sono discostate più del 10%, sia per quanto riguarda il calcolo dell’intensità e direzione del vento da immagini SAR, in cui l’errore rispetto al dato misurato è rimasto al di sotto del 15%, fornendo quindi una buona base per il monitoraggio della energia AC prodotta dagli impianti.In this work we present new methodologies aimed to support both planning and near-real-time monitoring of new generation solar and wind energy plants (CSP, CPV and wind off-shore) using satellite imagery. Such methodologies are currently being developed in the scope of SATENERG, a project funded by ASI (Italian Space Agency). In particular, for what concerns the concentrating solar energy plants (CSP and CPV) we developed a method to calculate solar irradiance at ground (and its direct normal component, that has primary importance in this type of plants) starting from satellite optical images. Then, using also detailed opto-electronic models of the plants and inverters, we are able to calculate the producible energy, which can be used to support either the design of potential plants (using historical series of satellite images) or the monitoring and performance analysis of existing plants (using near-real- time satellite imagery). Producible energy and other interesting parameters, like production efficiency, return on investment etc., are delivered through dedicated web services. In a similar way, we developed also a method to calculate the intensity and the direction of off-shore wind from satellite SAR (Synthetic Aperture Radar) images that permitted us, together with detailed models of wind turbine and inverters, to develop a new service in support to both planning and near-real-time monitoring activities of off-shore wind plants. The first applications of these methods gave successful results in several test cases: we obtained a maximum error of 10% for satellite retrieved direct normal solar irradiance and a maximum error of 15% for wind direction and intensity calculated from SAR images (with respect to in-situ measured data)

    A method for characterizing the stability of light sources

    Get PDF
    We describe a method for measuring small fluctuations in the intensity of a laser source with a resolution of 10⁻⁴. The current signal generated by a PIN diode is passed to a front-end electronics that discriminates the AC from the DC components, which are physically separated and propagated along circuit paths with different gains. The gain long the AC signal path is set one order of magnitude larger than that along the DC signal path in such a way to optimize the measurement dynamic range. We then derive the relative fluctuation signal by normalizing the input-referred AC signal component to its input-referred DC counterpart. In this way the fluctuation of the optical signal waveform relative to the mean power of the laser is obtained. A "Noise-Scattering-Pattern method" and a "Signal-Power-Spectrum method" are then used to analyze the intensity fluctuations from three different solid-state lasers. This is a powerful tool for the characterization of the intensity stability of lasers. Applications are discussed

    Far-field spectral characterization of conical emission and filamentation in Kerr media

    Full text link
    By use of an imaging spectrometer we map the far-field (θλ\theta-\lambda) spectra of 200 fs optical pulses that have undergone beam collapse and filamentation in a Kerr medium. By studying the evolution of the spectra with increasing input power and using a model based on stationary linear asymptotic wave modes, we are able to trace a consistent model of optical beam collapse high-lighting the interplay between conical emission, multiple pulse splitting and other effects such as spatial chirp.Comment: 8 pages, 9 figure

    Agronomic and Environmental Benefits of Cover Crops in Northern Italy

    Get PDF
    Cover crops have a number of benefits (reduction of nitrate leaching and of soil erosion, control of weed seed bank, increase of soil organic matter and increase of cash crop yield), but these were seldom quantified in cropping systems of Northern Italy. This experiment aimed to quantify some of these effects, by comparing cover crop species and their management techniques

    The Diacylglycerol Acyltransferase 3 of Chlamydomonas reinhardtii Is a Disordered Protein Capable of Binding to Lipids Derived from Chloroplasts

    Get PDF
    Understanding triacylglycerol (TAG) metabolism is crucial for developing algae as a source of biodiesel. TAGs are the main reservoir of energy in most eukaryotes. The final, rate-limiting step in the formation of TAGs is catalyzed by 1,2-diacylglycerol acyltransferases (DGATs). In the green alga Chlamydomonas reinhardtii, DGAT3 is phylogenetically related to plant DGAT3 but unrelated to other DGATs from eukaryotes, such as DGAT1 and DGAT2. In this study, we described the conformational preferences and the lipid-binding features of the DGAT3 from C. reinhardtii. To characterize its conformational stability and structural features, we used several biophysical probes, namely, fluorescence, circular dichroism (CD), and differential scanning calorimetry (DSC). Our results showed that the protein was mainly disordered, containing a small population of folded conformations in a narrow pH range (pH 8 to 10). The conformational stability of the folded structure of DGAT3 was very low, as shown by urea or guanidinium denaturations. Thermal denaturation, followed by fluorescence or CD, as well as calorimetric denaturation, followed by DSC, did not yield any transition in the pH range where DGAT3 acquired a “native-like” conformation. Furthermore, we used two approaches to demonstrate the interaction of DGAT3 with lipid membranes at the pH at which it had acquired a “native-like” conformation. The first involved the measurement of anisotropy and fluorescence quenching of the protein. The second approach focused on examining possible modifications of the biophysical properties of lipids due to their interaction with DGAT3, through anisotropy measurements and leakage assays. Both methods produced consistent results, suggesting that DGAT3 preferentially interacted with negatively charged membranes. These results will allow the design of a more efficient and stable DGAT3, as well as an in-depth understanding of how the metabolism of TAGs is accomplished in C. reinhardtii

    Genetic PTX3 deficiency and aspergillosis in stem-cell transplantation

    Get PDF
    BACKGROUND: The soluble pattern-recognition receptor known as long pentraxin 3 (PTX3) has a nonredundant role in antifungal immunity. The contribution of single-nucleotide polymorphisms (SNPs) in PTX3 to the development of invasive aspergillosis is unknown. METHODS: We screened an initial cohort of 268 patients undergoing hematopoietic stem-cell transplantation (HSCT) and their donors for PTX3 SNPs modifying the risk of invasive aspergillosis. The analysis was also performed in a multicenter study involving 107 patients with invasive aspergillosis and 223 matched controls. The functional consequences of PTX3 SNPs were investigated in vitro and in lung specimens from transplant recipients. RESULTS: Receipt of a transplant from a donor with a homozygous haplotype (h2/h2) in PTX3 was associated with an increased risk of infection, in both the discovery study (cumulative incidence, 37% vs. 15%; adjusted hazard ratio, 3.08; P=0.003) and the confirmation study (adjusted odds ratio, 2.78; P=0.03), as well as with defective expression of PTX3. Functionally, PTX3 deficiency in h2/h2 neutrophils, presumably due to messenger RNA instability, led to impaired phagocytosis and clearance of the fungus. CONCLUSIONS: Genetic deficiency of PTX3 affects the antifungal capacity of neutrophils and may contribute to the risk of invasive aspergillosis in patients treated (Funded by the European Society of Clinical Microbiology and Infectious Diseases and others) .with HSCT.Supported by grants from the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) (to Dr. Carvalho); the German Ministry for Education and Science (03Z2JN21, to Dr. Kurzai); the European Commission (FP7-HEALTH-2009-260338, to Dr. Romani; FP7-HEALTH-2011-280873, to Dr. Mantovani), the European Research Council (ERC-2008-AdG-233417, to Dr. Mantovani; ERC-2011-AdG-293714, to Dr. Romani), Associazione Italiana per la Ricerca sul Cancro (99629, to Dr. Mantovani); and Fundacao para a Ciencia e Tecnologia, Portugal (SFRH/BPD/46292/2008, to Dr. Carvalho; SFRH/BD/65962/2009, to Dr. Cunha; and SFRH/BPD/70783/2010, to Dr. Almeida)

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

    Get PDF
    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure
    corecore