1,721,086 research outputs found
An improved device for conversion of mechanical energy from sea waves to electric energy
No full textDevice for converting mechanical energy from sea waves into electric energy including at least a float and two rigid rods. The rods are preferably anchored to the seabed at one end, and to the float at another end. There are also two ballasts that effect their weight towards the sea bed to keep the free ends of the rods constantly in traction and free to rotate around their hinges. The float oscillates up and down along a vertical line due to waves. There are at least two cables that connect the free ends of the rods to a transmission shaft of a generator positioned along the vertical line so that the vertical, horizontal, or rotary oscillatory motion of the float caused by the waves generates an oscillatory motion of the rods which are pivoted on their respective hinges, and thus transfers rotary motion to the transmission shaft of the generator
3D numerical modeling of landslide-generated tsunamis around a conical island
No full textThis paper presents numerical computations of tsunamis generated by landslides falling along the flank of a conical island. The model used is the fully three-dimensional commercial code FLOW-3D, based on the VOF technique for the treatment of the free surface. The model results are compared against available experimental data that allow validation of the model, evaluation of its accuracy, and estimation of the computational costs. The main conclusion of this research is that the model is applicable at reasonable costs for a few accurate simulations that may be used for preparing precomputed inundation maps of coasts prone to the risk of tsunamis inundation
The influence of depth limited water conditions on the rock slope stability
Full text linkThe hydraulic stability of the armour layer of the rubble mound breakwaters have been widely discussed in the literature and
several empirical formulas have been proposed for design purposes. Nevertheless, few studies focused on the armour
stability in case of water depth limited water conditions.Then, the aim of the present research is to provide more
insights into the stability of the armour layer ranging from intermediate till extremely shallow water conditions. To this end, a 2D physical experiments have been carried out at the EUropean Maritime and Environmental Research (EUMER) laboratory of the University of Salento (Lecce), in presence of a 1V:30H foreshore. Tests aimed to investigate both the nearshore hydrodynamics and the hydraulic armour stability under different irregular waves attack. Experimental results are also compared with the damage evaluated from the empirical formulations available in literature, in order to investigate the predicted damage level in the shallowness
range analyzed
Effects of moored boats on the gradually varied free-surface profiles of river flows
No full textThe last mile of rivers often represents an option worth considering for the development of ports. This is particularly true in coastal areas that are densely developed. The simplest form of a port canal, i.e., boats moored along the banks, is an attractive option for the low investment required and the often acceptable residual wave motion. Some of the major rivers have thousands of boats moored along their banks. The effect of these floaters on the river levels during floods must be taken into account. The authors present a methodology based on the computation of the forces on a single boat or an array of boats that yields a quantification of the effect on the river levels. It essentially provides an iterative procedure for computing the value of the resistance coefficient to be used in hydraulic analysis. Theoretical predictions are satisfactorily confirmed by ad hoc experimental investigation
L'effetto dei natanti ormeggiati sui profili di rigurgito delle correnti a superficie libera
No full textLo sviluppo della portualità turistica in zone fortemente antropizzate e di grande valenza paesaggistica, come nel caso dell’Italia, richiede estrema attenzione nella scelta dei siti idonei ad ospitare nuove strutture per l’ormeggio dei natanti. I tratti terminali di alvei fluviali, sia principali che minori, sia naturali che regolarizzati, rappresentano spesso delle alternative di localizzazione in virtù del riparo naturale dal moto ondoso e dalla facilità di accesso dalle sponde. Si propone una metodologia atta a stimare quantitativamente l’azione dei natanti ormeggiati sull’andamento dei profili di rigurgito negli alvei fluviali. Secondo tale metodologia la presenza dei natanti può essere schematizzata come un incremento della scabrezza dell’alveo; in tal modo si possono utilizzare i metodi per il tracciamento dei profili di rigurgito con un coefficiente di resistenza opportunamente variato. I risultati teorici ottenuti sono confermati dall’evidenza sperimentale di un’indagine appositamente realizzata su modello fisico
Feasibility of Tsunami Early Warning Systems for small volcanic islands
No full textThis paper investigates the feasibility of Tsunami Early Warning Systems for small volcanic islands focusing on warning of waves generated by landslides at the coast of the island itself. The critical concern is if there is enough time to spread the alarm once the system has recognized that a tsunami has been generated. We use the results of a large scale physical model experiment in order to estimate the time that tsunamis take to travel around the island inundating the coast. We discuss how and where it is convenient to place instruments for the measurement of the waves
Feasibility of Tsunami Early Warning Systems for small volcanic islands RID A-2242-2009
No full textThis paper investigates the feasibility of Tsunami Early Warning Systems for small volcanic islands focusing on warning of waves generated by landslides at the coast of the island itself. The critical concern is if there is enough time to spread the alarm once the system has recognized that a tsunami has been generated. We use the results of a large scale physical model experiment in order to estimate the time that tsunamis take to travel around the island inundating the coast. We discuss how and where it is convenient to place instruments for the measurement of the waves
A simplified dynamical approach for storm surge prediction in the Adriatic Sea
No full textL'articolo tratta di un nuovo approccio per stimare gli eventi di innalzamento del livello medio marino dovuti alla marea meteorologica in Adriatico. Il fenomeno è noto perché è la causa di inondazione dlla città di Venezia.This paper describes a new simplified approach to estimate the intensity of storm surge events in the Adriatic Sea. The phenomenon at hand is well known because it causes the flooding of Venice. However, it may affect the whole Adriatic coastal zone
- …
