504 research outputs found
Implementation of pressure reduction valves in a dynamic water distribution numerical model to control the inequality in water supply
The analysis of water distribution networks has to take into account the variability of users’ water
demand and the variability of network boundary conditions. In complex systems, e.g. those
characterized by the presence of local private tanks and intermittent distribution, this variability
suggests the use of dynamic models that are able to evaluate the rapid variability of pressures and
flows in the network. The dynamic behavior of the network also affects the performance of valves
that are used for controlling the network. Pressure Reduction Valves (PRVs) are used for controlling
pressure and reducing leakages. Highly variable demands can produce significant fluctuation of the
PRV set point, causing related transient phenomena that propagate through the network and may
result in water quality problems, unequal distribution of resources among users, and premature wear
of the pipe infrastructure. A model was developed in previous studies and an additional module for
pressure control was implemented able to analyze PRVs in a fully dynamic numerical framework. The
model was demonstrated to be robust and reliable in the implementation of pressure management
areas in the network. The model was applied to a district of the Palermo network (Italy). The district
was monitored and pressure as well as flow data were available for model calibration
UN MODELLO NUMERICO NON STAZIONARIO PER LO STUDIO DEI FENOMENI TRANSITORI DURANTE IL RIEMPIMENTO DELLE RETI DI DISTRIBUZIONE IDRICA: ANALISI DELLA RESISTENZA IN MOTO NON UNIFORME
Enhanced RF Behavior Multi-Layer Thermal Insulation
Abstract This paper shows that it is possible to exploit the modulated metasurface concept to control the unwanted coupling between antennas that are installed on the same satellite. The metasurface is combined with a Multi-Layer thermal Insulation blanket to reduce its specular reflection by spreading the energy incoherently in the surrounding space. In the design, sub-wavelength radiating elements printed on thin substrate have been used to make the metasurface response azimuthally independent, and to keep the weight of blanket down. The comparison between simulations and measurements confirms the validity of the idea
Energy, water and environmental balance of a complex water supply system
The present paper describes the analysis of water and energy balance in a complex
urban water supply system. The analysis was carried out employing Life Cycle
Analysis (LCA) methodologies. The LCA approach was integrated with the
analysis of the system energy and water balance. For a real size water supply
system, based on the results of the individual LCAs, the current baseline was
constructed highlighting the water, energy and environmental (in terms of CO2eq
emissions in the atmosphere) costs of supplied water. Then, three different
mitigation measures have been evaluated: the first is based on energy production
by installation of photovoltaic systems; the second is based on energy recovery by
means of hydraulic turbines, exploiting the available pressure potential to produce
energy; the third based on energy optimization of pumping stations by installing
inverter systems, replacement of rotors with optimized blade profiles and
installation of automation systems and self-control. Also the possibility of
substituting some of the pipes of the water supply system was considered in the
recovery scenario in order to reduce leakages and recovery the energy needed for
leakages transport and treatment. The analysis of the results shown that energy
recovery scenario is the most reliable solution even without any pipe substitution.
Thanks to the recovery of energy and limiting the environmental impact of the
system, the CO2eq production per cubic meter of supplied water was reduced from
0.41 to 0.07 kg CO2eq/m3 of supplied water
Three-dimensional numerical simulations on wind- and tide-induced currents: The case of Augusta Harbour (Italy)
The hydrodynamic circulation in the coastal area of the Augusta Bay (Italy), located in the eastern part of Sicily, is analysed. Due to the heavy contamination generated by the several chemical and petrochemical industries active in the zone, the harbour was declared a Contaminated Site of National Interest. To mitigate the risks connected with the industrial activities located near the harbour, it is important to analyse the hydrodynamic circulation in the coastal area. To perform such analysis, a parallel 3D numerical model is used to solve the Reynolds-averaged momentum and mass balance, employing the k-? turbulence model for the Reynolds stresses. The numerical model is parallelized using the programing technology - Message Passing Interface (MPI) and applying the domain decomposition procedure.The Augusta Bay circulation is mainly due to the relative contribution of the wind force acting over the free surface and the tidal motion through the mouths. Due to the geometric complexity of the domain and the presence of several piers along the coast, a curvilinear boundary-fitted computational grid was used, where cells corresponding to land areas or to wharfs were excluded from the computation. Comparisons between numerical results and field measurements were performed. Three different simulations were performed to selectively isolate the effect of each force, wind and tide, acting in the considered domain. The current in the basin was successfully estimated on the basis of the numerical results, demonstrating the specific role of wind and tidal oscillation in the hydrodynamic circulation inside the harbour
Bayesian inference analysis of the uncertainty linked to the evaluation of potential flood damage in urban areas.
Flood damage in urbanized watersheds may be assessed by combining the flood depth–damage curves and the outputs of urban flood models. The complexity of the physical processes that must be simulated and the limited amount of data available for model calibration may lead to high uncertainty in the model results and consequently in damage estimation. Moreover depth–damage functions are usually affected by significant uncertainty related to the collected data and to the simplified structure of the regression law that is used. The present paper carries out the analysis of the uncertainty connected to the flood damage estimate obtained combining the use of hydraulic models and depth–damage curves. A Bayesian inference analysis was proposed along with a probabilistic approach for the parameters estimating. The analysis demonstrated that the Bayesian approach is very effective considering that the available databases are usually short
Atomistic subsemirings of the lattice of subspaces of an algebra
Let A be an associative algebra with identity over a field k. An atomistic
subsemiring R of the lattice of subspaces of A, endowed with the natural
product, is a subsemiring which is a closed atomistic sublattice. When R has no
zero divisors, the set of atoms of R is endowed with a multivalued product. We
introduce an equivalence relation on the set of atoms such that the quotient
set with the induced product is a monoid, called the condensation monoid. Under
suitable hypotheses on R, we show that this monoid is a group and the class of
k1_A is the set of atoms of a subalgebra of A called the focal subalgebra. This
construction can be iterated to obtain higher condensation groups and focal
subalgebras. We apply these results to G-algebras for G a group; in particular,
we use them to define new invariants for finite-dimensional irreducible
projective representations.Comment: 14 page
Insights into the effect of chitosan upon biofilm formation of several oral pathogenic microorganisms
Modified BMIA/CAG method for the electromagnetic analysis of large-scale problems of random rough surface scattering
An efficient technique based on two-dimensional Fast Fourier Transform (FFT) and linear interpolation is presented for the evaluation of the scattering by a rough terrain surface which is of interest in remote-sensing applications characterized by a very large correlation length. Such technique, where introduced in a BMIA/CAG method, can reduce the computation time appreciably
- …