Experimental investigation on a geocontainer Submerged reef

Geotextile sand containers (GSC) have been used as permanent construction elements in coastal works for more than 20 years,becoming more and more popular as an alternative to the most typical coastal structures. Aim of this work is to analyze the hydrodynamic, stability and morphodynamic response of a GSC submerged reef by means of an experimental campaign. The first investigated aspect concerned the hydrodynamics. The reflection and transmission coefficients for regular and random waves were determined: the reflection coefficient decreases with increasing of kh; the transmission coefficient decreases with the increase of the incident wave. As regards the stability of the structure, it was observed that the strongest waves were able to lift the row of GSC more exposed to the wave action. An instability curve for the GSC as a function of the hydrodynamic characteristics was then found. Flow visualization close to the reef was performed by means of ink, showing that the flow becomes asymmetric in the proximity of the structure. Concerning the morphodynamics, long-term tests were performed to calculate the scour. This reached its maximum value at the end of each test and it is present in all three cases. The scour causes serious problems of instability to the structure

Caratteristiche sismostratigrafiche di strutture sedimentarie diagnostiche dicorrenti di fondo nell\u2019off-shore del Golfo di Taranto.

L\u2019analisi integrata di dati multibeam e sismici ad altissima risoluzione (Chirp Sub-Bottom), acquisiti in un settore del Golfo di Taranto (Mare Ionio), ha permesso di identificare e classificare strutture sedimentarie diagnostiche di correnti di fondo (conturiti), formatesi nel tardo Quaternario. La classificazione proposta \ue8 basata sia su criteri sismo-stratigrafici che sulla comparazione con strutture analoge documentate da precedenti autori nei bacini oceanici [Faugeres et al., 1999 con rif.]. Nell\u2019area in esame sono stati identificati quattro settori (Alto dell\u2019Amendolara, Bacino di Corigliano, Bacino dell\u2019Amendolara ed Alto di Rossano-Cariati) caratterizzati da morfologia, pendenza e profondit\ue0 differente. Le strutture conturitiche sono state riconosciute prevalentemente nei settori NW e SE dell\u2019alto dell\u2019Amendolara, ad una profondit\ue0 compresa tra 130 m e 400 m e le geometrie interne ed esterne mostrano caratteristiche deposizionali ed erosive. Sono state classificate come sheeted drift le strutture sviluppate subparallelamente al profilo batimetrico, infill drift ed elongated drift le strutture caratterizzate da fosse ben sviluppate ed elementi erosivi quali fosse ed abraded surface. Sono stati osservati inoltre osservati sediment waves nel settore SW dell\u2019alto strutturale. Dall\u2019analisi integrata dei nuovi dati con quelli disponibili in letteratura \ue8 possibile ipotizzare che i fattori che hanno maggiormente influenzato tipologia, distribuzione areale e batimetrica dei depositi conturitici e degli elementi erosivi sono: a) morfologia del fondo marino; b) caratteristiche dei sedimenti (es. tessitura); c) variazione della velocit\ue0 della \u201cLevantine Intermediate Water come conseguenza delle d) variazioni eustatiche. Sono stati inoltre applicati in cascata i modelli bidimensionali CMS- Wave [Lin et al, 2006] per la propagazione dello spettro d\u2019onda, e CMS- Flow [Buttolph et al, 2006] per la circolazione interna, prendendo in considerazione i dati meteo marini forniti dall\u2019ECMWF nel punto di coordinate 39,5\ub0N, 17\ub0E, in modo da valutare le condizioni idrodinamiche in prossimit\ue0 del paraggio in esame. L\u2019integrazione dei dati indicati geologici/geofisici e dei risultati del codice di calcolo numerico ha permesso di ipotizzare un modello di circolazione della corrente \u201cLevantine Intermediate Water\u201d e valutare l\u2019influenza delle morfostrutture sulla circolazione delle acque profonde durante l\u2019ultima fase di abbassamento e stazionamento basso del livello del mare. Bibliografia Buttolph, A.,D., Reed, C.W., Kraus N., Wamsley, T.V., Ono, N., Larson, M.,Camenen, B., Hanson, H. Zundel, A.K., (2006). Two-Dimensional Depth-Averaged Circulation Model CMS-M2D: Version 3.0, Report 2, Sediment Transport and Morphology Change. ERDC/CHL TR-06-9 Vicksburg, MS: U.S. Army Engineer Research and Development Center. Lin, L., H. Mase, F. Yamada, and Z. Demirbilek. (2006). Wave-action balance equation diffraction (WABED) model: Tests of wave diffraction and reflection at inlets. Coastal and Hydraulics Engineering Technical Note ERDC/CHL CHETN-III-73. Vicksburg, MS: U.S. Army Engineer Research and Development Center. Faug\ue8res, J.C., Stow, D.A.V., Imbert, P., Viana, A.R. (1999). Seismic feature diagnostic of contourite drifts. Marine Geology 162, pp. 1-38

Coastal boulder production controlled by columnar joints of ignimbrite and extreme waves: insights from the high-energy coast of Pantelleria Island (Sicily Channel, Mediterranean Sea)

We examined the relationship between coastal boulder production and the volcanic rock features on the high-energy rocky coast of Pantelleria Island (Sicily Channel, Mediterranean Sea). We used geological data for 125 boulders and 21 rupture surfaces, integrated with fracture analysis, radiocarbon dating, numerical hydrodynamic analysis, and hindcast numerical model for wave characterization. The boulder field consists of isolated and grouped blocks detected along the shore platform and on the cliff top of Punta Sidere (northwestern coast of Pantelleria). Boulder production occurred through two mechanisms: (1) boulders were quarried from the platform edge of the low coast and cliff top as suggested by the same lithology of boulders and outcropping rocks, and by the similar shape of the boulders and rupture surfaces carved out into the rocky platform; (2) waves eroded the cliff foot, forming a notch, and boulders detached from cliff face and fell down to the shore platform. The morphometric analysis of the characteristics of boulders and outcropping rocks demonstrates that the columnar fractures controlled the boulders' polygonal surfaces and size. Whereas, the thickness of horizontal planes within the ignimbrite controlled the boulders' thickness. The numerical hydrodynamic analysis indicates that the quarrying, transport and deposition of boulders were mainly the result of storm waves up to 8 m high. The storm events occurred at different times, even recently, as suggested by two radiocarbon dating of biogenic encrustations collected from the boulders' surface and the presence of wood and plastic embedded within the boulder deposits

Photoelectric Emission from Interstellar Dust: Grain Charging and Gas Heating

We model the photoelectric emission from and charging of interstellar dust and obtain photoelectric gas heating efficiencies as a function of grain size and the relevant ambient conditions. Using realistic grain size distributions, we evaluate the net gas heating rate for various interstellar environments, and find less heating for dense regions characterized by R_V=5.5 than for diffuse regions with R_V=3.1. We provide fitting functions which reproduce our numerical results for photoelectric heating and recombination cooling for a wide range of interstellar conditions. In a separate paper we will examine the implications of these results for the thermal structure of the interstellar medium. Finally, we investigate the potential importance of photoelectric heating in H II regions, including the warm ionized medium. We find that photoelectric heating could be comparable to or exceed heating due to photoionization of H for high ratios of the radiation intensity to the gas density. We also find that photoelectric heating by dust can account for the observed variation of temperature with distance from the galactic midplane in the warm ionized medium.Comment: 50 pages, including 18 figures; corrected title and abstract field

Two-scale asymptotic homogenization in a MEMS auxetic structure for over etch identification

The development and optimization of Micro electro-mechanical systems (MEMS) devices, due to their small size scale, require testing and precise characterization. As an example, over etch, which is the deviation between the designed masks and the effective dimensions of the suspended parts, strongly influences the performances of MEMS; therefore, to predict the correct functioning of the device its actual value must be carefully identified. In this work, we propose an efficient, time-saving tool to identify fabrication imperfections in MEMS devices. In particular, we replace the complex geometry of a MEMS mechanical filter with an equivalent homogeneous medium, whose linear-elastic effective properties are evaluated employing two-scale asymptotic homogenization and we identify the over etch by minimizing the relative error between experimental data and corresponding predictions obtained for different combinations of over etch

Does Non-Moral Ignorance Exculpate? Situational Awareness and Attributions of Blame and Forgiveness

In this paper, we set out to test empirically an idea that many philosophers find intuitive, namely that non-moral ignorance can exculpate. Many philosophers find it intuitive that moral agents are responsible only if they know the particular facts surrounding their action. Our results show that whether moral agents are aware of the facts surrounding their action does have an effect on people’s attributions of blame, regardless of the consequences or side effects of the agent’s actions. In general, it was more likely that a situationally aware agent will be blamed for failing to perform the obligatory action than a situationally unaware agent. We also tested attributions of forgiveness in addition to attributions of blame. In general, it was less likely that a situationally aware agent will be forgiven for failing to perform the obligatory action than a situationally unaware agent. When the agent is situationally unaware, it is more likely that the agent will be forgiven than blamed. We argue that these results provide some empirical support for the hypothesis that there is something intuitive about the idea that non-moral ignorance can exculpate