404 research outputs found
Monitoring and long-term assessment of the Mediterranean Sea physical state through ocean reanalyses62
No full textThe Mediterranean Sea physical reanalysis [MEDREA, Simoncelli et al., 2014, Simoncelli et al., 2016] data set has been produced in the framework of MyOcean Project and distributed thought Copernicus Marine Environment Monitoring Service (CMEMS) catalogue (http://marine.copernicus.eu) since 2014 and yearly extended. It covers the time period 19872018 at 1/16° of spatial resolution forced by ERAInterim atmospheric reanalysis [Dee et al., 2011] and provides daily and monthly fields of temperature, salinity, sea surface height and currents. It assimilates along track sea level anomaly and temperature and salinity profiles. This data set is one of the most used by CMEMS users for many applications and studies among which the study of: the connectivity of Marine Protected Areas [Rossi et al., 2014]; the double diffusion processes [Meccia et al., 2016]; the cause of mass mortality that hit gorgonian forests at Montecristo Island [Turicchia et al., 2018]; the Mediterranean overturning circulation [Pinardi e al., 2019].PublishedRome4A. Oceanografia e clim
P. F. Grendler, The Roman Inquisition and the Venetian Press. 1540-1605, Princeton University Press
No full textExplosion venting in dust collectors: a critical review of standards for reduced pressure and reaction force duration
No full textDust explosions pose a critical risk in industrial settings. A global survey of incidents from 2016 to 2023 shows that dust collectors remain a leading source of dust fires and explosions, accounting for nearly 25% of all reported cases in that span. Although dust explosions in storage silos have been extensively studied, research specific to dust collectors is limited, leaving existing venting standards under-validated and potentially underestimating hazards. This work evaluates the accuracy of these standards by comparing their predictions of reduced pressure (P_red) and reaction force duration (t_r) against results from industrial-scale experiments. The findings reveal that current guidelines can significantly over- or underestimate these key explosion parameters, raising concerns about designs that may be insufficiently robust or overly conservative. The study concludes that revising venting requirements to incorporate updated experimental data can markedly improve predictive accuracy and system safety. By informing engineers, safety specialists, and policymakers, this research aims to advance more reliable, tailored explosion prevention and protection strategies for dust collector systems
Fire Resistance of Steel Rack Frames: Assessment, Reinforcement and Collapse Mitigation Strategies
No full textSteel rack frames are used to suitably store goods and products and are constructed by means the use of thin-walled cold-formed components. Their competitiveness on the market essentially depends on the total weight of the framed system. In fact, these structures allow for the storage of material that is hundreds or even thousands of times more expensive than the rack itself. Despite great efforts made on seismic and static design, limited attention has been given to the problem of fire design and to the robustness of such structures. No specific design rules or design procedures have been developed until now. Nowadays, the only way to protect these frames against fire is the use of active systems like sprinklers or controlled oxygen chambers. Unfortunately, these solutions cannot be always adopted and a suitable strategy that avoids the global structural collapse following a fire is still necessary. In this paper a parametric analysis is proposed to deeply understand the behavior of steel storage pallet racks against fire. In particular, starting from an existing rack configuration with nine bays and five storage levels, different fire scenarios were modeled by changing the fire position along the frame. Moreover, the progressive collapse of the rack is discussed, and a reinforcing strategy is proposed. Finally, an example of the application of a sprinkler system is discussed, showing the advantages and weaknesses of this solution
Telediagnosis of dental caries: possible or impossible? A pilot cross-sectional study
No full textObjectives: The aims of this study were to evaluate the effectiveness of teledentistry (based on a home intraoral imaging protocol) in detecting dental caries and to assess the accuracy of this method compared to clinical examination. Methods: Forty-three patients were recruited for the study. Using a protocol for taking intraoral photographs at home with a smartphone proposed by the Dental School of Verona, a remote diagnosis of dental caries (TD) was performed by an experienced dentist. The same caries sites were also assessed by clinical diagnosis (CD) by a second experienced dentist. Ten photos were taken at home in five different perspectives, with and without flash, and emailed to one of the authors. The best five photos were selected for telediagnosis. The International Caries Detection and Assessment System (ICDAS II) score was used for caries diagnosis. Statistical tests were performed: Sensitivity and specificity of TD, the positive and negative predictive value of TD (PPV-NPV), and Spearman correlation to evaluate the relationship between the scores of TD and CD. Results: A total of 430 photographs were submitted; TD was performed on 215 photographs and 43 patients were visited. A total of 1201 teeth were analyzed. The sensitivity of TD was 74.0, the specificity was 99.1, the PPV of TD was 91.7, and the NPV was 96.4. The Spearman correlation was 0.816, showing a very strong correlation between the values obtained with TD and CD. Conclusions: The study showed good potential for TD, which proved to be a feasible method to combine with routine caries diagnosis in daily preventive dentistry practice
Problemi di tutela di Trapa natans L. nella Riserva Naturale delle Valli del Mincio (MN)
No full textLa Riserva Naturale delle Valli del Mincio, istituita dalla Regione Lombardia nel 1984, è caratterizzata da un denso sistema di canali alimentati dal fiume Mincio, che convergono in specchi d’acqua comunemente detti “giochi”, circondati da canneti e cariceti.
Per contribuire alla conservazione di specie vegetali rare presenti nella Riserva, è stata osservata la distribuzione locale della rizofita annuale Trapa natans L. (Trapaceae), studiandone il dinamismo spazio-temporale nell’arco di 6 anni. La specie, paleotemperata-subtropicale, è tipica d’acque stagnanti con fondo fangoso, generalmente profonde 1-2 m, eutrofiche e con contenuto di carbonati variabile. La sua presenza in Italia è oggi assai rara, limitata alle regioni settentrionali (Piemonte, Lombardia, Emilia, Veneto e Friuli); nelle regioni peninsulari, per le quali esistono segnalazioni più o meno recenti (Toscana, Umbria, Lazio e Puglia), è presumibilmente scomparsa (1). Inclusa nelle Liste Rosse a livello nazionale e regionale (2, 3), T. natans è stata inserita nel recente elenco delle “specie protette a raccolta regolamentata” di cui alla L. R. 10/2008 della Regione Lombardia. La specie forma un’associazione diffusa nell’Europa Centrale e Meridionale (Trapetum natantis Kárpáti 1963) in cui presenta un grado di copertura dal 40 al 100 %, con forte tendenza a creare popolamenti monofitici.
Nel corso di queste indagini sono state osservate, dal 2003 al 2008, 6 stazioni individuate nella Riserva; per 4 di esse è stato possibile effettuare un confronto con dati aggiornati al 2002 (4). In generale, due stazioni hanno manifestato forti contrazioni (riduzione della superficie occupata pari o superiore al 70% nel tempo di tre generazioni), due sono rimaste invariate, due si sono formate recentemente (2007) e poi espanse. La minaccia più evidente è costituita dall’invasione di specie alloctone, come Myocastor coypus Molina, che si ciba dei germogli di T. natans, e Nelumbo nucifera Gaertn., introdotta nella riserva nel 1921. Tutte le stazioni di T. natans sono pertanto riconducibili a un’unica location (Minaccia 8.1, IUCN vers. 3.0). Per converso, fuori della Riserva, era presente al momento dell’ultimo rilievo un’estesissima stazione (circa 10 ha), nel Lago di Mezzo, probabilmente originata dall’apporto di frutti dai bacini a monte. N. nucifera continuava invece ad espandersi, per via vegetativa, unicamente nella Riserva e nel Lago Superiore. Secondo i criteri IUCN 2001 applicati (A e C), includendo anche la stazione di T. natans fuori dalla Riserva la categoria di rischio passa da EN a VU. La valutazione dello stato di conservazione è stata condotta a livello locale, coi conseguenti limiti applicativi nella definizione di assessment e status secondo il protocollo IUCN (5). Questo tipo di analisi ha tuttavia aiutato a valutare l’efficienza della Riserva nella conservazione della specie e i dati raccolti potranno costituire un contributo per indagini su scala più ampia (6).
1) A. Scoppola, C. Blasi (2005) Palombi Editori, Roma.
2) F. Conti, A. Manzi, F. Pedrotti (1992) Tipar, Società Botanica Italiana, Roma.
3) F. Conti, A. Manzi, F. Pedrotti (1997) Società Botanica Italiana, Università di Camerino.
4) M. Tomaselli, M. Gualmini, O. Spettoli (2002) Collana Annali, Facoltà di Scienze Matematiche Fisiche e Naturali, Università degli Studi di Parma.
5) IUCN (2003) Guidelines for Application of IUCN Red List Criteria at regional levels: version 3.0
6) G.Rossi, R.Gentili, T. Abeli, B.Foggi (2008) Inf. Bot. Ital, 40 (suppl.1
Many-body Green's function approach to lattice thermal transport
No full textRecent progress in understanding thermal transport in complex crystals has highlighted the prominent role of heat conduction mediated by interband tunneling processes, which emerge between overlapping phonon bands (i.e., with energy differences smaller than their broadenings). These processes have recently been described in different ways, relying on the Wigner or Green-Kubo formalism, leading to apparently different results, which question the definition of the heat-current operator. Here, we implement a full quantum approach based on the Kubo formula, elucidating analogies and differences with the recently introduced Wigner or Green-Kubo formulations, and extending the description of thermal transport to the overdamped regime of atomic vibrations, where the phonon quasiparticle picture breaks down. We rely on first-principles calculations on complex crystals with ultralow conductivity to compare numerically the thermal conductivity obtained within the aforementioned approaches, showing that at least in the quasiparticle regime the differences are negligible for practical applications
DERRICK CRANE ROBUSTNESS SCENARIOS
No full textThe paper deals with derrick cranes (derricks) that are equipment typically used in the mining industry and focuses on the analysis of few robustness scenarios. Derricks are composed of built-up steel members which are widely and efficiently used in hoisting applications due to their high payloads at relevant outreaches. During the in-service use, local damages might occur and as such, the aim of the paper is to study how such damages influence the overall structural performance. In particular, reference was made to a derrick for which six geometrical configurations and five different damage scenarios have been analysed. Owing it to the extensive use of angles in the built-up compo-nent of each derrick, structural analyses have been carried out by using a commercial refined finite element analysis package (FEAP) offering the warping torsion as an additional degree of freedom for each beam node. Research out-comes allow for a clear identification of the parts of a derrick that should be protected and well-designed to guarantee a robust structure for its entire in-service lif
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