78 research outputs found
Monitoring and modelling interactions between the montagna dei fiori aquifer and the castellano stream (Central Apennines, Italy)
Groundwater is the most used water resource around the world, but due to population growth and climate change the alluvial lowland aquifers are often polluted and over-exploited. Thus, more and more frequently water managers need to shift their attention to mountain regions to identify groundwater resources for drinking purposes. This study presents a monitoring and modelling approach that allowed to quantify the inflow from the "Montagna dei Fiori" fractured aquifer to the Castellano stream. Continuous monitoring of flow discharge and temperature during an entire hydrological year (2018-2019) at two monitoring stations along the stream allowed to discriminate between the baseflow (on average, 0.891 m3/s) and the run-off (on average, 0.148 m3/s) components. A hydrogeological basin-wide numerical flow model (using MODFLOW-2005) was set up using information from hydrogeological and geomechanical surveys. The model was calibrated using the daily baseflow observations made in the Castellano stream (R2 = 0.75). The calibrated model allowed to quantify groundwater/surface water interactions. After an automated sensitivity analysis (using MODFLOW-2000), the recharge was found to be the most uncertain parameter, followed by the hydraulic conductivity zonation. This methodology could be applied in other mountain regions where groundwater monitoring networks are usually lacking to improve water resources management
Correction: Groundwater circulation and earthquake-related changes in hydrogeological karst environments: a case study of the Sibillini Mountains (central Italy) involving artificial tracers
The original version of this article was revised due to a retrospective Open Access order
Interplay between shape and roughness in early-stage microcapillary imbibition.
Flows in microcapillaries and associated imbibition phenomena play a major role across a wide spectrum of practical applications, from oil recovery to inkjet printing and from absorption in porous materials and water transport in trees to biofluidic phenomena in biomedical devices. Early investigations of spontaneous imbibition in capillaries led to the observation of a universal scaling behavior, known as the Lucas-Washburn (LW) law. The LW allows abstraction of many real-life effects, such as the inertia of the fluid, irregularities in the wall geometry, and the finite density of the vacuum phase (gas or vapor) within the channel. Such simplifying assumptions set a constraint on the design of modern microfluidic devices, operating at ever-decreasing space and time scales, where the aforementioned simplifications go under serious question. Here, through a combined use of leading-edge experimental and simulation techniques, we unravel a novel interplay between global shape and nanoscopic roughness. This interplay significantly affects the early-stage energy budget, controlling front propagation in corrugated microchannels. We find that such a budget is governed by a two-scale phenomenon: The global geometry sets the conditions for small-scale structures to develop and propagate ahead of the main front. These small-scale structures probe the fine-scale details of the wall geometry (nanocorrugations), and the additional friction they experience slows the entire front. We speculate that such a two-scale mechanism may provide a fairly general scenario to account for extra dissipative phenomena occurring in capillary flows with nanocorrugated walls
Localization from quantum interference in one-dimensional disordered potentials
We show that the tails of the asymptotic density distribution of a quantum
wave packet that localizes in the the presence of random or quasiperiodic
disorder can be described by the diagonal term of the projection over the
eingenstates of the disordered potential. This is equivalent of assuming a
phase randomization of the off-diagonal/interference terms. We demonstrate
these results through numerical calculations of the dynamics of ultracold atoms
in the one-dimensional speckle and quasiperiodic potentials used in the recent
experiments that lead to the observation of Anderson localization for matter
waves [Billy et al., Nature 453, 891 (2008); Roati et al., Nature 453, 895
(2008)]. For the quasiperiodic case, we also discuss the implications of using
continuos or discrete models.Comment: 5 pages, 3 figures; minor changes, references update
Numerical validation of the quantum lattice Boltzmann scheme in two and three dimensions
Scelta del tracciante ideale per indagini idrogeologiche: risultati preliminari da test in laboratorio
Tracers techniques are a good tool to investigate groundwater
dynamics; they are essential to perform measurement of hydrogeological
parameters of aquifers. This study was aimed at characterizing
adsorption, effective porosity and pore water velocity in soil
samples collected in a hydrographic basin of Marche Region (Italy).
This basin has the typical geologic and hydrogeological features of
many basins in Central Italy. Therefore. the principal aim is to
evaluate the best tracer to be used for hydrogeological purpose (i.e.
groundwater tracer test and aquifer parameter estimation). Adsorption
has been investigated by means of laboratory batch tests using
different tracers and involving different soils. In literature some application
of tracers both to laboratory scale and to field scale can be
found. Column tests have been performed also to test the effectiveness
of different test equipment and to investigate the influence of some
test parameters on the calculation of effective porosity and pore water
velocity. These considerations and test results are very useful to advise
the choice of the best tracer to be used in tracer field tests
Insights into Bending Stiffness Modeling of Elementary Flexure Hinges
Flexure hinges are widely used in mechanical devices, especially for micro- or even nano-scale applications, where conventional joints based on conjugate surfaces prove unsuitable. However, to achieve accurate motion of devices whose joints are flexure hinges, knowledge of stiffness models that correlate applied forces or bending moments with the resulting displacements is required. Nonlinear bending models are typically too complex and difficult to implement. Therefore, it is preferred to use linear models, which admit analytical solutions. The purpose of this paper is to show what is lost in terms of accuracy in reducing a nonlinear bending stiffness model associated with a flexure hinge when simplifications are made to obtain an analytical solution. An analysis of the simplification process leading to a linear stiffness model and its analytical solution is presented. From this study arises an increased awareness of flexure joints in terms of the accuracy obtained with their stiffness models, suggesting important information to the user in choosing the level of complexity required to model them in a specific application. A comparison between analytical and numerical results is provided in the form of maps and tables so as to make that choice as clear as possible
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