394 research outputs found

    A Fourier transform for sheaves on Lagrangian families of real tori

    Full text link
    We systematically develop a transform of the Fourier-Mukai type for sheaves on symplectic manifolds XX of any dimension fibred in Lagrangian tori. One obtains a bijective correspondence between unitary local systems supported on Lagrangian submanifolds of XX and holomorphic vector bundles with compatible unitary connections supported on complex submanifolds of the relative Jacobian of XX (suitable conditions being verified on both sides).Comment: Latex, 30 pages (in a4wide format), no figures. v2: Minor expository changes, typos corrected. v3: Final version to appear in two parts in J. Geom. Phy

    A Quantitative Methodology to Measure Injector Fouling Through Image Analysis

    Get PDF
    Abstract The use of vegetables oils in a compression ignited internal combustion engine presents some critical issues as the large amount of carbon deposits on the tip of injectors, which significantly influence emissions and engine performance. A previous draft methodology was developed by the authors, based on images capture and post-processing. The carbon deposit was correlated with the number of pixels in the gray scale, so it was possible to determine a Fouling Index. First results showed interesting perspectives and some limits: the aim of the present work is the optimization of the test bench and methodology. At first an improvement of image acquisition, increasing sampling frequency and image resolution, is performed, replacing the old camera with a digital microscope and improving both injector and microscope positioning. The test bench prototype has been realized with the aid of 3D printing, obtaining fundamental mechanical components. Also an alternative methodology is proposed to evaluate carbon deposits volume through a Volumetric Index. The new methodology validation was done using images sampled with the previous test bench. The performances of the Fouling index and of the new Volumetric Index were compared and fouling was examined in the real case of a diesel engine, fed with diesel and sunflower oil. Results show a greater reliability of the new Volumetric Index

    A Martini coarse-grained model of the calcein fluorescent dye

    Get PDF
    Calcein leakage assays are a standard experimental set-up for probing the extent of damage induced by external agents on synthetic lipid vesicles. The fluorescence signal associated with calcein release from liposomes is the signature of vesicle disruption, transient pore formation or vesicle fusion. This type of assay is widely used to test the membrane disruptive effect of biological macromolecules, such as proteins, antimicrobial peptides and RNA and is also used on synthetic nanoparticles with a polymer, metal or oxide core. Little is known about the effect that calcein and other fluorescent dyes may have on the properties of lipid bilayers, potentially altering their structure and permeability. Here we develop a coarse-grained model of calcein that is compatible with the Martini force field for lipids. We validate the model by comparing its dimerization free energy, aggregation behavior at different concentrations and interaction with a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membrane to those obtained at atomistic resolution. Our coarse-grained description of calcein makes it suitable for the simulation of large calcein-filled liposomes and of their interactions with external agents, allowing for a direct comparison between simulations and experimental liposome leakage assays

    Fundamental solutions for the super Laplace and Dirac operators and all their natural powers

    Get PDF
    The fundamental solutions of the super Dirac and Laplace operators and their natural powers are determined within the framework of Clifford analysis.Comment: 12 pages, accepted for publication in J. Math. Anal. App

    i rexfo life an innovative business model to reduce food waste

    Get PDF
    Abstract Every year the food produced and wasted consumes a volume of water equal to 250 km3, requires around 30% of the world agricultural land, and it is responsible for the emission of 3,3 billion tons of greenhouse gases. The direct economic consequences of food waste are ranging around 750 billion dollars per year (FAO source). i-REXFO designs an innovative business model with the objective of reducing significantly the amount of landfilled food waste. The actions are economically sustained by public incentives, tax reductions and private revenues from energy valorization of residual food waste. Uptaking the good practices from other EU countries (Denmark) the project will develop a tool to design the integrated model, optimize it from a technical, economic and environmental point of view and transfer it to other EU regions. i-REXFO will increase consumer awareness on food waste reduction in retail malls and HORECA while facilitating the sale and donation to charities and food banks of close to expiration and aesthetically not adequate food; it will also remove the barriers that hamper the use of food residues in biogas plants. The actions are economically sustained from energy valorization of food waste in biogas plant that use the digestate as fertilizer, closing the cycle. I-REXFO will achieve an overall reduction of 17000 tons/year of food waste landfilled during the project duration and in the after life phase. This will correspond to an overall reduction of 41000 tons of CO2 equivalent emissions

    Pyrolysis of Olive Stone for Energy Purposes

    Get PDF
    Abstract Pyrolysis of biomass is a promising technology for the production of distributed and renewable energy on small and micro-scale since it produces a gas with relatively high calorific value, which can be burned in an internal combustion engine or in a microturbine; pyrolysis also generates by products (char and tar) which can be used to provide energy to the process or for cogeneration purposes. This research is aimed at the exploitation of waste from agricultural production processes, in particular olive mill wastes whose management has critical environmental and disposal costs; the yields of pyrogas, tar and char obtained from the pyrolysis of olive stone in a batch reactor was measured. Pyrogas produced is sampled through a line for the sampling of condensable substances in accordance with existing regulations, CEN/TS 15439, and once purified from water vapor and tars is analyzed with micro-GC. The data collected is used to perform mass and energy balances and to determine the content of tars and the Low Heating Value (LHV) of the gas produced

    Hermite and Gegenbauer polynomials in superspace using Clifford analysis

    Full text link
    The Clifford-Hermite and the Clifford-Gegenbauer polynomials of standard Clifford analysis are generalized to the new framework of Clifford analysis in superspace in a merely symbolic way. This means that one does not a priori need an integration theory in superspace. Furthermore a lot of basic properties, such as orthogonality relations, differential equations and recursion formulae are proven. Finally, an interesting physical application of the super Clifford-Hermite polynomials is discussed, thus giving an interpretation to the super-dimension.Comment: 18 pages, accepted for publication in J. Phys.

    Efficiency Enhancement for an S-Band Axial Vircator Using 5-Stage Two-Step Tapered Radiators

    Get PDF
    An S-band multistage axial virtual cathode oscillator with efficiency enhancement for high pulsed power electromagnetic applications is presented. The Particle-in-Cell (PIC) results of the designed 5-stage Vircator, with two-step negative tapering in the reflectors, carried out by CST Studio suite 2021 simulation code show a peak power value of 5.54 GW and an efficiency value of 13.65% at 2.45 GHz, under a beam voltage and current equal to 520 kV and 20 kA, respectively

    Bounded Model Checking for Probabilistic Programs

    Get PDF
    In this paper we investigate the applicability of standard model checking approaches to verifying properties in probabilistic programming. As the operational model for a standard probabilistic program is a potentially infinite parametric Markov decision process, no direct adaption of existing techniques is possible. Therefore, we propose an on-the-fly approach where the operational model is successively created and verified via a step-wise execution of the program. This approach enables to take key features of many probabilistic programs into account: nondeterminism and conditioning. We discuss the restrictions and demonstrate the scalability on several benchmarks

    Clinical usefulness of splanchnic oxygenation in predicting necrotizing enterocolitis in extremely preterm infants:a cohort study

    Get PDF
    Background: Impaired intestinal microcirculation seems to play an important role in the pathogenesis of necrotizing enterocolitis (NEC). A previous study showed that a SrSO2 &lt; 30% is associated with an increased risk of developing of NEC. We aimed to determine the clinical usefulness of the cut off &lt; 30% for SrSO2 in predicting NEC in extremely preterm neonates.Methods: This is a combined cohort observational study. We added a second cohort from another university hospital to the previous cohort of extremely preterm infants. SrSO2 was measured for 1–2 h at days 2–6 after birth. To determine clinical usefulness we assessed sensitivity, specificity, positive and negative predictive values for mean SrSO2 &lt; 30. Odds ratio to develop NEC was assessed with generalized linear model analysis, adjusting for center.Results: We included 86 extremely preterm infants, median gestational age 26.3 weeks (range 23.0-27.9). Seventeen infants developed NEC. A mean SrSO2 &lt; 30% was found in 70.5% of infants who developed NEC compared to 33.3% of those who did not (p = 0.01). Positive and negative predictive values were 0.33 CI (0.24–0.44) and 0.90 CI (0.83–0.96), respectively. The odds of developing NEC were 4.5 (95% CI 1.4–14.3) times higher in infants with SrSO2 &lt; 30% compared to those with SrSO2 ≥ 30%.Conclusions: A mean SrSO2 cut off ≥ 30% in extremely preterm infants between days 2–6 after birth may be useful in identifying infants who will not develop NEC.</p
    corecore