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The paper shows that a Finite Volume method with an HLL Riemann solver may incorrectly reproduce the depth-averaged velocity under uniform flow in a channel with non-rectangular cross section. A specific treatment for evaluating the fluxes at the sides has been proposed and tested.

Legionella isolation was performed by cultural method, but different molecular techniques were implemented to identify Legionella strains in order to undertake the epidemiological investigation and establish the link with the source of infection. Our study was focused on a genotypic approach to evaluate Legionella contamination of a hospital hot water network (HWN) in association with the ISO11731-1998. The phylogenetic relationship between strains permitted to elaborate an environmental risk map. Materials/Methods: From October 2013 to July 2016, 547 hot water samples were analyzed to detect and enumerate Legionella in a HWN treated by a new disinfectant (WTP828) based on hydrogen peroxide (H2O2 ) + silver salts (Ag+ ). Isolates were serotyped using agglutination test and genotyped by mip gene sequencing and Sequence- Based Typing (SBT). Phylogenetic analysis was performed on the Phylogeny.fr platform and the tree was reconstructed by the maximum likelihood method. Results: Culture method permitted to identify 37% of positive samples belonging to L. pneumophila SG1 (60%) and L. species (40%). SBT assigned ST1 and ST104 to 123 samples of L. pneumophila. The mip gene sequencing identified inner L. species, L. anisa and L. rubrilucens in 82 positive samples. Phylogenetic analysis performed on strains of L. rubrilucens 1 / 2 inserimenti and L. anisa confirmed the presence of two separate clusters. The 100% of homology in 7 genes investigated in L. pneumophila strains did not permit to elaborate phylogenetic correlation. Conclusion: The genotypic approach used during environmental monitoring in a HWN under disinfection treatment might support the study of Legionella colonization. The elaboration of a phylogenetic map of isolates can help to correlatestrains in response to the disinfection treatment. These knowledges might support the HealthAuthority to rapidly undertake the epidemiological investigation and preventives measures.

Contamination of industrial cooling towers has been identified as the cause of sporadic cases and outbreaks of legionellosis. The epidemiological data showed as the risk of Legionella infection coming from cooling tower is underestimated. The aim of the study was to assess the effectiveness of different disinfection treatments on Legionella colonization, performed within an industrial Cooling Tower System (CTS) starting from opening to closing season. Materials/Methods: Cold water samples were collected monthly from May to October 2016, during an environmental monitoring of industrial CTS nearby Bologna, Italy. Legionella culture was carried out according to ISO11731-1998. Two disinfection treatments were subsequently performed in relation to microbiological levels found. The first performed for 7 days based on hydrogen peroxide (H2O2 )/silver salts (Ag+) at shock concentration of 100 mg L-1 in synergic association to an antialgal treatment and the second performed by sodium hypochlorite at 50 mg L-1 for 15 days. 1 / 2 inserimenti Results: Ourdata show the presence of L. pneumophila SG8 at a level of 5,06 log10 UFC L -1 after the water CTS filling, that required a shock treatment performed for one week by H2O2 /Ag+ . This treatmentincreases a Legionella contamination level until 6,14 log10 UFC L-1 . These data required a stop of CTS activity, washing of circuit by peracetic acid and two subsequently shock hyperchlorination. After 15 days we observed a decrease of Legionella level to 1,90 log10 UFC L-1. maintained for all tested period. Conclusions: Our data confirm the role of routinely environmental monitoring before and during CTS operating conditions. The introduction of preliminary procedures before the disinfection treatment as anti-scale treatment, washing of CTS, measures of physical-chemicalparameters and control of microbiological contaminants, permit a good performance of CTS, reducing the risk for the stakeholders and public health.

Distributed Synthetic Aperture Radar (DSAR) is defined as a SAR in which the signal emitted by the transmitter and scattered from the area of interest is not collected by a single receiver but by many, conveniently distributed, formation flying, receivers. The concept of distributed aperture can enable new SAR working modes, but more important, thanks to passive operations, can achieve very high performance through a series of very compact, low weight, agile, satellite platforms. Such a distributed space system can be regarded as a system in which the payload functionality is broken apart and distributed among the different elements of the system. While fractionation and formation flying may lead to many advantages, distributed space systems pose a number of technological and operational issues at system and subsystem level. This paper focuses on basic system requirements and formation flying aspects relevant to DSAR. In particular, trajectory design approaches that can fulfil payload requirements while relaxing formation control issues are addressed. Long term stability is also investigated.

In the present paper the mathematical character of the two-phase depth-averaged morphodynamical model proposed by Di Cristo et. al (2014) is discussed. In particular, in this model the bed-load concentration is dynamically evaluated provided that an algebraic expression for bed-load thickness is assumed. To this aim, some adaptations of empirical correlations proposed for uniform equilibrium flow conditions may be considered, modifying the differential structure of the problem. In this paper the model eigenstructure is studied considering thee different expressions of the bed-load thickness, showing that the mathematical character of the model is significantly affected by the adopted relationship. In particular, when relationships accounting for only the bed-load volume for unit bottom area or both the solid phase velocity and the bed-load volume for unit bottom surface are considered the model is hyperbolic. In contrast, a hyperbolicity loss is detected for the expression which accounts for only the liquid velocity. The domains of nonhyperbolicity are individuated in terms of the relevant dimensionless parameters and represented through shaded maps. The results of the analysis aim to guide the users to define the correct number of boundary conditions and to choose the most appropriate numerical solver in simulating fast geomorphic transients.

Fast geomorphic transients may involve complex scenarios of sediment transport, occurring as bed-load (i.e. saltating, sliding and rolling) in the region close to the bottom, or as suspended load in the upper region of the flow. These two modalities of sediment transport may even coexist or alternate each-other during the same event, owing to the variability of the shear stress. The modeling of similar processes is therefore a really challenging task, for which usual representation of the flow as a mixture may result unsatisfactorily. In the present paper, we propose a two-phase depth-averaged model which is able to deal with both bed-load and suspended sediment transport. The mathematical model is derived from the expression of mass and momentum conservation equations, separately for liquid and sediment phase. The equations for the solid phase are written separately for bed-load and suspended load region. The bed-load layer thickness is assumed variable with the actual shear stress, while the solid concentration is described by the differential equations. The entrainment/deposition of sediment from the bed towards the bed-load layer is evaluated by a formula based on a modified van Rijn mobility parameter, while for the suspended sediment a first-order kinetic law is considered. The behavior of the resulting model under uniform conditions of flow complies with some of the proposed empirical formulations for bed-load thickness, average particle velocity and solid discharge. A numerical method based on a finite-volume approach is employed for the simulation of experiments in which both bed load and sediment transport are present. Even without any detailed calibration, simulated and experimental results show reasonable agreement.

https://doi.org/10.1061/(ASCE)HY.1943-7900.0000538

Nel presente contributo si analizza l’effetto della variabilità del coefficiente di resistenza sulla crescita delle roll-waves nella fase iniziale della loro formazione. Lo sviluppo delle roll-waves viene analizzato schematizzando il fenomeno come l’evoluzione di un perturbazione sia istantanea sia pulsante nel tempo con frequenza assegnata. In entrambi i casi l’influenza della variabilità dell’indice di resistenza dalle variabili idrodinamiche risulta essere rilevante. I risultati ottenuti con i due schemi sono poi confrontati con quelli di un modello numerico 1D alle acque basse.

Barcelona, Spain

The thermodynamics of Bi-In-Sn lead-free solder alloys has been studied by two different experimental techniques: torsion-effusion and differential scanning calorimetry. The results show that this ternary system at fixed Bi composition, X-Bi = 0.20, and 565 K behaves as a non-ideal system with exothermic Delta(mix) H-T(0) passing through a minimum at X-In = 0.58 and X-sn = 0.22. In the whole range of the quantity X-Sn/(X-Sn + X-In) T and at 1050 K the average value of the bismuth activity is 0.14 +/- 0.02 which implies an average activity coefficient of Bi equal to 0.70 +/- 0.01. The Bi activity in ternary alloys at 1000 K with variable X-Bi and fixed ratio rho = X-Sn/X-In = 0.85 has been measured. The excess integral free energy change for the mixing, Delta(mix) G(T)(0) (xs), has also been evaluated by making use of both the torsion-effusion experimental and literature data T for Bi-Sn and Bi-In binary systems. Under these conditions, the ternary system is not a regular solution and the entropy contribution to the free energy of mixing is dominating the Gibbs energy.