509 research outputs found

    Deteriogenic flora of the Phlegraean Fields Archaeological Park: ecological analysis and management guidelines

    Get PDF
    Biodeterioration, the alteration caused by living organisms, on historical buildings and stone monuments is a well-known problem affecting two-thirds of the world’s cultural heritage. The study of the flora growing on wall surface is of particular importance for the assessment of the risk of biodeterioration of stone artifacts by vascular plants, and for maintenance planning. In this study, we investigate how rock type, exposure and inclination of the wall affect the biodeteriogenic flora at 13 sites of the Archaeological Park of the Phlegraean Fields located in the province of Naples, in southern Italy. For each site, we analysed randomly selected square areas with 2 × 2 m size, representing the different vegetation types in terms of vascular plant species cover. The total num - ber of plant species recorded was 129, belonging to 43 families. Erigeron sumatrensis, Sonchus tenerrimus and Parietaria judaica are the most commonly reported species, while Capparis orientalis is the species with the highest average coverage. Substrate type, exposure and surface inclination affect the floristic composition, with the average plant cover significantly higher on vertical surfaces and at western and southern expo - sure. All the main biodeteriogenic vascular plant species grow on more or less porous lythotype like yellow tufa, conglomerate and bricks. Finally, woody plants eradications methods are proposed by the tree cutting and local application of herbicides, to avoid stump and root sprouting and to minimize the dispersion of chemicals in the sur- rounding environment

    Thermoelectric efficiency of three-terminal quantum thermal machines

    Get PDF
    The efficiency of a thermal engine working in linear response regime in a multi-terminals configuration is discussed. For the generic three-terminal case, we provide a general definition of local and non-local transport coefficients: electrical and thermal conductances, and thermoelectric powers. Within the Onsager formalism, we derive analytical expressions for the efficiency at maximum power, which can be written in terms of generalized figures of merit. Also, using two examples, we investigate numerically how a third terminal could improve the performance of a quantum system, and under which conditions non-local thermoelectric effects can be observed.Comment: 21 pages, 10 figures. Final versio

    Energy helps accuracy: electroweak precision tests at hadron colliders

    Get PDF
    We show that high energy measurements of Drell-Yan at the LHC can serve as electroweak precision tests. Dimension-6 operators, from the Standard Model Effective Field Theory, modify the high energy behavior of electroweak gauge boson propagators. Existing measurements of the dilepton invariant mass spectrum, from neutral current Drell-Yan at 8 TeV, have comparable sensitivity to LEP. We propose measuring the transverse mass spectrum of charged current Drell-Yan, which can surpass LEP already with 8 TeV data. The 13 TeV LHC will elevate electroweak tests to a new precision frontier.Comment: 8 pages, 5 figures, 2 tables. Added: CEPC reach, projected reach on heavy vector triplet

    Separation of heat and charge currents for boosted thermoelectric conversion

    Full text link
    In a multi-terminal device the (electronic) heat and charge currents can follow different paths. In this paper we introduce and analyse a class of multi-terminal devices where this property is pushed to its extreme limits, with charge andand heat currents flowing in different reservoirs. After introducing the main characteristics of such heatchargeheat-charge currentcurrent separationseparation regime we show how to realise it in a multi-terminal device with normal and superconducting leads. We demonstrate that this regime allows to control independently heat and charge flows and to greatly enhance thermoelectric performances at low temperatures. We analyse in details a three-terminal setup involving a superconducting lead, a normal lead and a voltage probe. For a generic scattering region we show that in the regime of heat-charge current separation both the power factor and the figure of merit ZTZT are highly increased with respect to a standard two-terminal system. These results are confirmed for the specific case of a system consisting of three coupled quantum dots.Comment: 12 pages, 8 figure

    Chaotic ratchet dynamics with cold atoms in a pair of pulsed optical lattices

    Get PDF
    We present a very simple model for realizing directed transport with cold atoms in a pair of periodically flashed optical lattices. The origin of this ratchet effect is explained and its robustness demonstrated under imperfections typical of cold atom experiments. We conclude that our model offers a clear-cut way to implement directed transport in an atom optical experiment.Comment: 7 pages, 7 figure

    On the wave equation on moving domains: regularity, energy balance and application to dynamic debonding

    Full text link
    We revisit some issues about existence and regularity for the wave equation in noncylindrical domains. Using a method of diffeomorphisms, we show how, through increasing regularity assumptions, the existence of weak solutions, their improved regularity and an energy balance can be derived. As an application, we give a rigorous definition of dynamic energy release rate density for some problems of debonding, and we formulate a proper notion of solution for such problems. We discuss the consistence of such formulation with previous ones, given in literature for particular cases.Comment: 36 page

    Fish population

    Get PDF
    Le strutture sommerese , che possono essere di diversa tipologia (blocchi di roccia, elementi in calcestruzzo, relitti e rottami metallici ecc.), svolgono diversi tipi di funzione e l’ambiente spesso si adatta ad esse integrandole e sfruttandone le caratteristiche. Le strutture infatti vengono costruite con l’intento di proteggere il fondale dagli effetti dell’attività di pesca a strascico e fornire una zona di protezione e riproduzione per gli organismi bentonici che qui trovano rifugio (effetto “tigmotropico”). Proprio per quest’ultima ragione, le strutture e la loro posizione è ben nota ai pescatori che qui trovano abbondanza di organismi. Scopo del presente studio è quello di valutare l’incremento della biomassa ittica presso la zona del Dosso di Santa Croce (Golfo di Trieste – Alto Adriatico) in seguito alla sistemazione e maturazione delle strutture sommerse. Lo studio è stato condotto mediante pescate sperimentali effettuate a giugno 2003, maggio e agosto 2004, luglio 2005 e mediante osservazioni raccolte durante immersioni subacquee.Il presente studio è stato finalizzato alla caratterizzazione del Dosso di Santa Croce (Golfo di Trieste – Alto Adriatico) in termini di morfobatimetria e di distribuzione dei banchi di pesce presenti in questa zona. A tal fine è stato utilizzato un “echosounder” che permette, tramite riflessione degli impulsi acustici inviati, di individuare banchi di pecse o plankon, valutandone la relativa taglia, stimare abbondanza e densità dei medesimi organismi, studiarne il comportamento e le dinamiche migratorie e mappare il fondale. Lo strumento ha permesso, nel presente lavoro, di valutare in maniera semplice la densità e l’abbondanza relative dei banchi di pesce, ma la conversione in valori assoluti è stata resa difficoltosa dall’impossibilità di prelevare specie nell’area, sottoposta a protezione. Pertanto uno strumento utile da utilizzare in abbinamento all’echosounder sembrerebbe poter essere il “visual census” (campionamento visivo) per valutare le specie presenti nei banchi

    SPH simulation of periodic wave breaking in the surf zone. A detailed fluid dynamic validation

    Get PDF
    The estimation of wave breaking and run-up on sloped beaches is a relevant issue in different coastal engineering applications. The present study stresses on the capabilities of a Smoothed Particle Hydrodynamics (SPH) solver, with optimal numerical and physical parameters, to accurately simulate the complex flow field in the surf zone and run-up region. Numerical results are compared with high quality experimental measurements of the local flow field in terms of instantaneous and phase averaged values. The selected test case regards the propagation and breaking of regular non-linear waves on a smooth impermeable plane slope. The comparison is based on a complete set of 128 consecutive non-linear regular waves. The level of accuracy of the numerical results and the ability of the model to reproduce the periodic flow in the surf-zone is provided. Current limitations and uncertainty sources are identified and discussed to guide future developments

    General purpose readout board {\pi} LUP: overview and results

    Full text link
    This work gives an overview of the PCI-Express board π\piLUP, focusing on the motivation that led to its development, the technological choices adopted and its performance. The π\piLUP card was designed by INFN and University of Bologna as a readout interface candidate to be used after the Phase-II upgrade of the Pixel Detector of the ATLAS and CMS experiments at LHC. The same team in Bologna is also responsible for the design and commissioning of the ReadOut Driver (ROD) board - currently implemented in all the four layers of the ATLAS Pixel Detector (Insertable B-Layer, B-Layer, Layer-1 and Layer-2) - and acquired in the past years expertise on the ATLAS readout chain and the problematics arising in such experiments. Although the π\piLUP was designed to fulfill a specific task, it is highly versatile and might fit a wide variety of applications, some of which will be discussed in this work. Two 7th^{th}-generation Xilinx FPGAs are mounted on the board: a Zynq-7 with an embedded dual core ARM Processor and a Kintex-7. The latter features sixteen 12.5\,Gbps transceivers, allowing the board to interface easily to any other electronic board, either electrically and/or optically, at the current bandwidth of the experiments for LHC. Many data-transmission protocols have been tested at different speeds, results will be discussed later in this work. Two batches of π\piLUP boards have been fabricated and tested, two boards in the first batch (version 1.0) and four boards in the second batch (version 1.1), encapsulating all the patches and improvements required by the first version.Comment: 6 pages, 10 figures, 21th Real Time Conference, winner of "2018 NPSS Student Paper Award Second Prize
    corecore