8,809 research outputs found
Strategic planning optimisation of "Napoli Est" water distribution system
The District Meter Areas (DMA) design is an innovative methodology of water networks management, based on the pressure patterns control and on the water flows monitoring, in order to reduce water losses and to optimize the water systems management. A District Meter Area is an area supplied from few water inputs, into which discharges can be easily measured to determine leaks. So, the DMA design represents an alternative to the traditional approach based on heavy looped distribution network. In the present paper the DMA design of the âNapoli Estâ water distribution system (approximately 65.000Ă·70.000 customers), performed with the support of the Water Agency ARIN S.p.A., is discussed.
After analysis of authorized consumption, by means of a monitoring campaign of water flows over the area, the system water balance was performed, showing significant water losses, as a consequence of high pressure patterns. This situation was confirmed by the high number of maintenance operations performed in the area during the year 2005. In order to characterize the piezometric heads on the network, ARIN S.p.A. supplied to the installation of six pressure transducers in the most vulnerable areas. The water level in the supply reservoir was also measured in order to estimate its influence on the network pressure heads.
Hydraulic simulations were carried out with the EPANET software version 2.0 applied to a network layout resulted from the system âskeletonizationâ, achieved by eliminating out of order pipes, integrating pipelines of same diameter and roughness, replacing dead-end branches and small networks supplied by a single junction with an equivalent discharge.
After the skeletonizated network was calibrated, several hypothesis of designing and implementing DMA to reduce physical losses were performed, providing adequate operating pressure of the system. Many numerical simulations were performed to guarantee adequate head pressure especially for peak hours demand, break of transmission mains and fire hydrant service. A chlorine residuals analysis was also effected, by simulating the transport and decay of chlorine through the network.
District Meter Areas, therefore, were designed, and the corresponding hydraulic and water quality investigations and simulations were carried out. Six District Meter Areas were planned, assembling 14 intercepting valves and 9 pressure reducing valves to prevent the downstream pressure head from exceeding the set value, achieving a remarkable water saving, approximately equal to 34% of the physical losses, corresponding to 16% of system input volume
Constraints on the active tectonics of the Friuli/NW Slovenia area from CGPS measurements and three-dimensional kinematic modeling
We use site velocities from continuous GPS (CGPS) observations and kinematic
modeling to investigate the active tectonics of the Friuli/NW Slovenia area. Data from 42
CGPS stations around the Adriatic indicate an oblique collision, with southern Friuli
moving NNW toward northern Friuli at the relative speed of 1.6 to 2.2 mm/a. We
investigate the active tectonics using 3DMove, a three-dimensional kinematic model tool.
The model consists of one indenter-shaped fault plane that approximates the Adriatic
plate boundary. Using the ââfault-parallel flowââ deformation algorithm, we move the
hanging wall along the fault plane in the direction indicated by the GPS velocities. The
resulting strain field is used for structural interpretation. We identify a pattern of
coincident strain maxima and high vorticity that correlates well with groups of
hypocenters of major earthquakes (including their aftershocks) and indicates the
orientation of secondary, active faults. The pattern reveals structures both parallel and
perpendicular to the strike of the primary fault. In the eastern sector, which shows more
complex tectonics, these two sets of faults probably form an interacting strike-slip
system
Multiscale fluid--particle thermal interaction in isotropic turbulence
We use direct numerical simulations to investigate the interaction between
the temperature field of a fluid and the temperature of small particles
suspended in the flow, employing both one and two-way thermal coupling, in a
statistically stationary, isotropic turbulent flow. Using statistical analysis,
we investigate this variegated interaction at the different scales of the flow.
We find that the variance of the fluid temperature gradients decreases as the
thermal response time of the suspended particles is increased. The probability
density function (PDF) of the fluid temperature gradients scales with its
variance, while the PDF of the rate of change of the particle temperature,
whose variance is associated with the thermal dissipation due to the particles,
does not scale in such a self-similar way. The modification of the fluid
temperature field due to the particles is examined by computing the particle
concentration and particle heat fluxes conditioned on the magnitude of the
local fluid temperature gradient. These statistics highlight that the particles
cluster on the fluid temperature fronts, and the important role played by the
alignments of the particle velocity and the local fluid temperature gradient.
The temperature structure functions, which characterize the temperature
fluctuations across the scales of the flow, clearly show that the fluctuations
of the fluid temperature increments are monotonically suppressed in the two-way
coupled regime as the particle thermal response time is increased. Thermal
caustics dominate the particle temperature increments at small scales, that is,
particles that come into contact are likely to have very large differences in
their temperature. This is caused by the nonlocal thermal dynamics of the
particles..
Converting NAD83 GPS heights into NAVD88 elevations with LVGEOID, a hybrid geoid height model for the Long Valley volcanic region, California
A GPS survey of leveling benchmarks done in Long
Valley Caldera in 1999 showed that the application of the
National Geodetic Survey (NGS) geoid model GEOID99 to
tie GPS heights to historical leveling measurements would
significantly underestimate the caldera ground deformation (known from other geodetic measurements). The NGS
geoid model was able to correctly reproduce the shape of the
deformation, but required a local adjustment to give a realistic estimate of the magnitude of the uplift. In summer 2006,
the U.S. Geological Survey conducted a new leveling survey
along two major routes crossing the Long Valley region from
north to south (Hwy 395) and from east to west (Hwy 203 â
Benton Crossing). At the same time, 25 leveling bench marks
were occupied with dual frequency GPS receivers to provide a
measurement of the ellipsoid heights. Using the heights from
these two surveys, we were able to compute a precise geoid
height model (LVGEOID) for the Long Valley volcanic region.
Our results show that although the LVGEOID and the latest
NGS GEOID03 model practically coincide in areas outside
the caldera, there is a difference of up to 0.2 m between the
two models within the caldera. Accounting for this difference
is critical when using the geoid height model to estimate the
ground deformation due to magmatic or tectonic activity in the
calder
Dual-PEEC Modeling of a Two-Port TEM Cell for VHF Applications
Two-port TEM cells with rectangular cross section are commonly used to produce plane electromagnetic waves with high electric field. The non-uniform structure makes the use of numerical methods extremely useful in the design phase in order to achieve a very good behavior of the TEM cell over a wide frequency range of operation. In this paper an extended version of PEEC is used to study a real device and results are compared with experimental ones
Low-energy quantum string cosmology
We introduce a Wheeler-De Witt approach to quantum cosmology based on the
low-energy string effective action, with an effective dilaton potential
included to account for non-perturbative effects and, possibly, higher-order
corrections. We classify, in particular, four different classes of scattering
processes in minisuperspace, and discuss their relevance for the solution of
the graceful exit problem.Comment: Extended version to appear in the Review section of Int. J. Theor.
Phys. A 13 (1998). The new permanent address is added. An updated collection
of papers on the pre-big bang scenario is available at
http://www.to.infn.it/~gasperi
Homogeneous and inhomogeneous contributions to the luminescence linewidth of point defects in amorphous solids: Quantitative assessment based on time-resolved emission spectroscopy
The article describes an experimental method that allows to estimate the
inhomogeneous and homogeneous linewidths of the photoluminescence band of a
point defect in an amorphous solid. We performed low temperature time-resolved
luminescence measurements on two defects chosen as model systems for our
analysis: extrinsic Oxygen Deficient Centers (ODC(II)) in amorphous silica and
F+ 3 centers in crystalline Lithium Fluoride. Measurements evidence that only
defects embedded in the amorphous matrix feature a dependence of the radiative
decay lifetime on the emission energy and a time dependence of the first moment
of the emission band. A theoretical model is developed to link these properties
to the structural disorder typical of amorphous solids. Specifically, the
observations on ODC(II) are interpreted by introducing a gaussian statistical
distribution of the zero phonon line energy position. Comparison with the
results obtained on F+ 3 crystalline defects strongly confirms the validity of
the model. By analyzing experimental data within this frame, we obtain separate
estimations of the homogenous and inhomogeneous contributions to the measured
total linewidth of ODC(II), which results to be mostly inhomogeneous.Comment: 8 pages, 4 figure
Keeping watch over Colombiaâs slumbering volcanoes
The Volcanological and Seismological Observatories of Manizales, Pasto and Popayan (Colombian Geological Survey) monitor and study the active volcanoes of Colombia using seismological, geodetic, geochemical and other techniques. Since 2009, permanent GNSS stations have been installed to complement classical geodetic measurements (e.g., tilt, EDM). At the moment, there are a total of 20 GNSS stations installed at Nevado del Ruiz, Cerro MachĂn, PuracĂ© and Galeras volcanoes.
Nevado del Ruiz has remained the most dynamic of the active Colombian volcanoes since its tragic eruption of 13 November 1985. The most significant deformation occurred between 2007 and 2012, when inflation, associated with magma migration and several small to moderate explosive eruptions in 2012 (VEI less or equal to 3), was observed.
Galeras has experienced more than 25 moderate Vulcanian eruptions (VEI less or equal to 3) since 1989. In particular, the deformation network detected significant signals associated with magma migration and the extrusion of lava domes in 1991, 2005, 2008 and 2012.
Puracé volcano has been the site of more than 10 minor eruptive episodes (VEI=2) in the past century, most recently in 1977. Monitoring of this volcano started in 1994. Unrest at Puracé since that time has been characterized by significant increases in seismic activity but with little or no deformation.
We employ GAMIT/GLOBK to process GPS data from the monitoring network with support from the Volcano Disaster Assistance Program (U.S. Geological Survey). Additionally, differential processing is carried out using the commercial package Trimble 4D Control. Preliminary results for 2012 show no significant deformation at Puracé and Galeras volcanoes. On the other hand, the time series from Nevado del Ruiz shows a minor inflation (2-4 cm/yr) associated with the eruptive activity of 2012
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