Non-intrusive measurements of wave-induced flow over dikes by means of a combined ultrasound doppler velocimetry and videography

The performance of non-intrusive instruments, such as acoustic profilers and cameras, to describe the wave-induced flow processes over maritime dike crest was investigated in experiments carried out at the University of Bologna. Direct and derived measurements from the acoustic probes deployed along the structure crest were discussed in relation to the observed backscatter rates. Image processing was implemented by means of clustering algorithm, in order to detect the free surface during overtopping events and characterize wave front propagation over the dike crest. UVP data were processed to indirectly derive flow depths and overtopping rates and compare them with the direct measurements in order to assess the measurement reliability and discuss their limits. Individual overtopping volume distribution as obtained by UVP data were estimated and compared with well-consolidated formulations, showing a good agreement. Finally, suggestions for an appropriate use of non-intrusive instruments to characterize a shallow, transient and aerated flow were provided, such as the control of the artificial seeding density, the use of a bi-static UVP configuration and adjustments to light exposure

Coupled wave-2D hydrodynamics modeling at the Reno River mouth (Italy) under climate change scenarios

This work presents the results of the numerical study implemented for the natural area of Lido di Spina, a touristic site along the Italian coast of the North Adriatic Sea, close to the mouth of River Reno. High-resolution simulations of nearshore dynamics are carried out under climate change conditions estimated for the site. The adopted modeling chain is based on the implementation of multiple-nested, open-source numerical models. More specifically, the coupled wave-2D hydrodynamics runs, using the open-source TELEMAC suite, are forced at the offshore boundary by waves resulting from the wave model (SWAN) simulations for the Adriatic Sea, and sea levels computed following a joint probability analysis approach. The system simulates presentday scenarios, as well as conditions reflecting the high IPCC greenhouse concentration trajectory named RCP8.5 under predicted climate changes. Selection of sea storms directed from SE (Sirocco events) and E-NE (Bora events) is performed together with Gumbel analysis, in order to define ordinary and extreme sea conditions. The numerical results are here presented in terms of local parameters such as wave breaking position, alongshore currents intensity and direction and flooded area, aiming to provide insights on how climate changes may impact hydrodynamics at a site scale. Although the wave energy intensity predicted for Sirocco events is expected to increase only slightly, modifications of the wave dynamics, current patterns, and inland flooding induced by climate changes are expected to be significant for extreme conditions, especially during Sirocco winds, with an increase in the maximum alongshore currents and in the inundated area compared to past conditions. \ua9 2018 by the authors

Beach monitoring and morphological response in the presence of coastal defense strategies at riccione (Italy)

The coastal area at Riccione, in the southern Emilia-Romagna littoral region, is exposed to erosive processes, which are expected to be enhanced by climate change. The beach, mostly composed of fine sand, is maintained through various defense strategies, including frequent nourishment interventions for balancing the sediment deficit and other experimental solutions for reducing coastal erosion. Artificial reshaping of the beach and \u201ccommon practices\u201d in the sediment management redefine the beach morphology and the sediment redistribution almost continuously. These activities overlap each other and with the coastal dynamics, and this makes it very difficult to evaluate their effectiveness, as well as the role of natural processes on the beach morphological evolution. Topo-bathymetric and sedimentological monitoring of the beach has been carried out on a regular basis since 2000 by the Regional Agency for Prevention, Environment and Energy of Emilia-Romagna (Arpae). Further monitoring of the emerged and submerged beach has been carried out in 2019\u20132021 in the framework of the research project STIMARE, focusing on innovative strategies for coastal monitoring in relation with erosion risk. The aim of this study is to assess the coastal behavior at the interannual/seasonal scale in the southern coastal stretch of Riccione, where the adopted coastal defense strategies and management actions mostly control the morphological variations in the emerged and submerged beach besides the wave and current regime. The topo-bathymetric variations and erosion/accretion patterns provided by multitemporal monitoring have been related to natural processes and to anthropogenic activities. The morphological variations have been also assessed in volumetric terms in the different subzones of the beach, with the aim of better understanding the onshore/offshore sediment exchange in relation with nourishments and in the presence of protection structures. The effectiveness of the adopted interventions to combat erosion, and to cope with future climate change-related impacts, appears not fully successful in the presence of an overall sediment deficit at the coast. This demonstrates the need for repeated monitoring of the emerged and submerged beach in such a critical setting

Coherent states for exactly solvable potentials

A general algebraic procedure for constructing coherent states of a wide class of exactly solvable potentials e.g., Morse and P{\"o}schl-Teller, is given. The method, {\it a priori}, is potential independent and connects with earlier developed ones, including the oscillator based approaches for coherent states and their generalizations. This approach can be straightforwardly extended to construct more general coherent states for the quantum mechanical potential problems, like the nonlinear coherent states for the oscillators. The time evolution properties of some of these coherent states, show revival and fractional revival, as manifested in the autocorrelation functions, as well as, in the quantum carpet structures.Comment: 11 pages, 4 eps figures, uses graphicx packag

Real-life data on potential drug-drug interactions in patients with chronic hepatitis C viral infection undergoing antiviral therapy with interferon-free DAAs in the PITER Cohort Study

Background There are few real-life data on the potential drug-drug interactions (DDIs) between anti-HCV direct-acting antivirals (DAAs) and the comedications used. Aim To assess the potential DDIs of DAAs in HCV-infected outpatients, according to the severity of liver disease and comedication used in a prospective multicentric study. Methods Data from patients in 15 clinical centers who had started a DAA regimen and were receiving comedications during March 2015 to March 2016 were prospectively evaluated. The DDIs for each regimen and comedication were assigned according to HepC Drug Interactions (www.hep-druginteractions.org). Results Of the 449 patients evaluated, 86 had mild liver disease and 363 had moderate-to-severe disease. The use of a single comedication was more frequent among patients with mild liver disease (p = 0.03), whereas utilization of more than three drugs among those with moderate-to-severe disease (p = 0.05). Of the 142 comedications used in 86 patients with mild disease, 27 (20%) may require dose adjustment/closer monitoring, none was contraindicated. Of the 322 comedications used in 363 patients with moderate-to-severe liver disease, 82 (25%) were classified with potential DDIs that required only monitoring and dose adjustments; 10 (3%) were contraindicated in severe liver disease. In patients with mild liver disease 30% (26/86) used at least one drug with a potential DDI whereas of the 363 patients with moderate-to-severe liver disease, 161 (44%) were at risk for one or more DDI. Conclusions Based on these results, we can estimate that 30-44% of patients undergoing DAA and taking comedications are at risk of a clinically significant DDI. This data indicates the need for increased awareness of potential DDI during DAA therapy, especially in patients with moderate-to-severe liver disease. For several drugs, the recommendation related to the DDI changes from "dose adjustment/closer monitoring" in mild to moderate liver disease, to "the use is contraindicated" in severe liver disease

A numerical study for the stability analysis of articulated concrete mattress for submarine pipeline protection

Submarine pipelines commonly operate along coastlines for wastewater draining or for fluid transportation from platforms at deep waters. Depending on the installation area, they are subject to waves and currents and the common solution to improve the pipe stability is to cover them with bitumen or articulated concrete block mattresses. The aim of the present study is the investigation of wave-induced forces on the articulated concrete block mattress covering a submarine pipe, laid on seabed, by using a RANS numerical model

SIMULAZIONE NUMERICA DI ONDE FRANGENTI CON UN MODELLO BIFASE PER FLUIDI INCOMPRIMIBILI

Viene presentato un modello numerico bifase per fluidi viscosi incomprimibili per la simulazione della propagazione di onde frangenti in acque basse. Il modello, che rappresenta una estensione del codice COBRAS0 (COrnell BReaking wAves and Structures), si basa sulle equazioni di Navier-Stokes, mediate secondo Favre-Reynolds e chiuse dal modello di turbolenza k-ε, ed include il trattamento della miscela acqua-aria. Il metodo Volume Of Fluid (VOF) è utilizzato per il tracciamento della superficie libera: la frazione di fluido contenuta in una cella si propaga secondo l’algoritmo di avvezione Donor-Acceptor mentre il criterio di ricostruzione dell’interfaccia è stato implementato per assicurare con un miglior grado di accuratezza la conservazione della massa. Il modello è stato validato attraverso una simulazione del movimento di una bolla d’aria nell’acqua; attraverso una simulazione di crollo di diga e dal confronto con dati di un test sperimentale condotto da Martin e Moyce (1952) ne è emersa una migliore rappresentazione del processo. I risultati della propagazione di onde frangenti su una spiaggia impermeabile sono stati confrontati con i relativi dati sperimentali (Lin, 1999): l’effetto della movimentazione dell’aria e delle bolle intrappolate nell’acqua ha un contributo non trascurabile sulla dissipazione dell’energia durante il frangimento dell’onda

Free surface boundary conditions for spilling waves: theoretical approach and numerical implementation

The recent advancement of numerical modeling has given valuable insights in the knowledge of wave transformation and interaction with coastal structures. In particular, the twophase flow formulation gives advantages towards a more accurate reproduction of the processes and a deeper understanding of the dynamics developing at wave breaking, where an aerated splashing regime is observed. However, such an approach is found to be computationally expensive, especially in the case of large-scale analyses. Aim of the present paper is to describe a novel single-phase numerical model where the adopted free surface boundary conditions take into account the multiphase mixing layer forming at surface deformation. Preliminary comparisons with available data on hydraulic jumps, stationary counterparts of bores, reveal good performances of the model