509 research outputs found
Deteriogenic flora of the Phlegraean Fields Archaeological Park: ecological analysis and management guidelines
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
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
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
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 heat currents flowing in different reservoirs. After
introducing the main characteristics of such
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
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
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
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
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
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
This work gives an overview of the PCI-Express board LUP, focusing on
the motivation that led to its development, the technological choices adopted
and its performance. The LUP 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 LUP 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
7-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
12.5Gbps 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 LUP 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
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