131,523 research outputs found
Modena: un “dissesto” di lungo periodo. Nuovi dati sull’alluvionamento solido della città. Modena: a long duration “disarrangement”. New data concerning the natural sedimentation onto the city.
No full textVengono presentati nuovi dati stratigrafici e cronologici relativi alle dinamiche di alluvionamento solido del territorio negli ultimi 2500 anni rilevati nell’ambito urbano e suburbano della città di Modena nel corso di interventi di archeologia preventiva operati negli ultimi anni dalla Soprintendenza per i Beni Archeologici dell’Emilia-Romagna. Si sottolinea la distinzione tra episodio alluvionale ordinariamente inteso e relativa registrazione sedimentaria, ricordando il differente valore delle subfacies che caratterizzano l’ambiente alluvionale. Si evidenzia la differenza esistente nelle registrazioni sedimentarie tra gli ambiti suburbani orientale ed occidentale della città antica.
Si sottolinea come il tasso di sedimentazione naturale valutato anche sul medio periodo (decine di migliaia di anni) risulti doppio rispetto al tasso di subsidenza naturale.
Si caldeggiano future osservazioni sedimentologiche di estremo dettaglio per l’individuazione di eventuali fenomenologie naturali di tipo particolare riferibili non soltanto alle dinamiche fluviali.
New stratigraphic and radiochronometric data concerning the solid flooding of the ancient city of Modena and its surroundings during the last 2500 years are illustrated and discussed. These data were recorded during preventive archaeological essays performed by Soprintendenza per i Beni Archeologici dell’Emilia-Romagna during the last years. The difference between alluvial episode and its related sedimentary record as well as the interpretative value of the different alluvial environment subfacies are highlighted . The differences existing in the sedimentary record characterizing western and eastern surroundings of the ancient city are illustrated. The natural sedimentation rate evaluated through more thousand years appears to be double with respect to the natural subsidence rate. New detailed geoarchaeological surveys will have to inspect and recognize if other kinds of natural phenomena than the fluvial one happened and were stratigraphically recorded in Modena territory
The volume electric field integral equation for dielectric cloaking at any frequency regime
No full textAnalytical manipulations on the Volume Electric Field Integral Equation (VEFIE) are performed for cloaking dielectric volumes (with maximum dimension D) from incoming fields (with wavelength λ). Three main mathematical conditions are derived for any frequency regime (D/λ). The first confirms plasmonic cloaking in quasi-static regime; the second demonstrates plasmonic cloaking beyond the subwavelength limit; the third ensures cloaking with all-natural dielectric materials beyond the quasi-static frequency band
The late-Antiquity environmental crisis in Emilia Region (Po river plain, Northern Italy): geoarchaeological evidence and paleoclimatic considerations
No full textFor about four decades in Italy local, scientific literature has occasionally dealt with fluvial avulsions, suggesting they should be considered as genetically linked to a peculiar climatic worsening that occurred in the late-6th century AD (the so-called “Paul the Deacon Deluge”). Research performed by the Soprintendenza per i Beni Archeologici dell’Emilia-Romagna over the last few years has allowed us to better define the timing of a more articulated alluvial history, mainly concerning the Roman Imperial age and Late-Antiquity (1st-6th century AD). The main stratigraphic details of fourteen selected archaeological excavation sites (eleven recently surveyed and three reviewed from the literature) performed in the cities of Modena, Bologna and related surroundings have been summarized. Eleven 14C datings, ranging between the years 130 AD and 810 AD, allowed us to chronologically delimit a first frame for the riverbed network behaviour during ancient times in the central part of the region. The alluvial process appeared to be continuous throughout the time span examined. The fan trench was the most sensitive reach of the river system. It started to aggrade during the 4th century AD, during the 5th century AD and probably after the end of the 6th century AD, a number of avulsions occurred. This indicates that the fluvial system was in a metastable equilibrium whose behavioural threshold was finally overcome. Hence, the importance of the supposed year 589 AD crisis (the “Deluge”) appears to be less than that previously supposed. The riverbed aggradation became evident immediately after the Roman empire’s economic and demographic crisis of the 3rd century AD, and it was probably due to the loss of the land preservation systems once created in the mountain catchment areas. The long duration of the aggradation phase suggests that more than one human settlement phase in the minor catchment areas and/or a minor climatic worsening pulse probably occurred during the 5th century AD. The starting of the aggradation also coincided with the end of the Petit Maclu 1 high level phase of the European lakes. Notwithstanding this, the climate’s role as a forcing co-factor can still be hard to evaluate positively due to the lack of local climatic proxy data
Limidi. Fondo Magnavacca e Ca' Bisi
No full textLa realizzazione di prospezioni sul terreno, anche con l'uso di carotaggi, ha consentito di verificare l'estensione e la consistenza di una terramara "sepolta". I materiali disponibili datano il contesto al Bronzo recente
Carpi, Savana.
No full textIl contributo illustra i dati noti relativi ad una delle terramare più note e meglio conservate. Le informazioni derivate da prospezioni sistematiche sul terreno hanno consentito di verificare e precisare i dati relative alle strutture perimetrali (argine e fossato) e alla cronologia che vede una massiccia occupazione del sito durante la fase avanzata del Bronzo medio e nel Bronzo recente
A Comparison of Fractal Dimension and Spectrum Coefficient Characterization of 1/fα Noise
No full textA command governor approach to plasma shape control
No full textThe paper deals with the application of the socalled Command Governor (CG) approach to the shape control of plasmas in thermonuclear fusion reactors. A primal internal loop controlling the plasma-wall gaps is designed first and a CG device is then tuned to modify, whenever necessary, the reference to the primal loop, taking into account constraints due to voltages saturations on the converters, currents limitations in the active coils, force limits on the mechanical structures, minimum clearance between the plasma and the vacuum chamber wall, maximum induced forces on coils. The reference signal modification is accomplished through an online optimization procedure which embodies plasma model forecasts computed along a finite time virtual receding horizon as usual in model predictive paradigms. The ITER (International Thermonuclear Experimental Reactor) tokamak is assumed as a case study. Numerical simulations are carried out on a numerical nonlinear model taking into account almost a hundred of constraints. ©2009 IEEE
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