Search results for "Armour"
showing 8 items of 8 documents
Eco-geomorphological connectivity and coupling interactions at hillslope scale in drylands: Concepts and critical examples
2020
The diagnosis of land degradation requires a deep understanding of ecosystem functioning and evolution. In dryland systems, in particular, research efforts must address the redistribution of scarce resources for vegetation, in a context of high spatial heterogeneity and non-linear response. This fact explains the prevalence of eco-hydrological perspectives interested in runoff processes and, the more recent, focused on connectivity as an indicator of system resource optimisation. From a geomorphological perspective and reviewing the concepts of eco-hydro-geomorphological interactions operating in ecosystems, this paper explores the effects of erosion on vegetation configuration through two …
Andalusian hauberk identifiers. A new example
2019
El trabajo está dedicado a una nueva pequeña chapa circular de metal con inscripción incisa en árabe. Aporta la lectura y traducción de su texto y sitúa el objeto en un grupo especial dentro de la metalística medieval islámica. Es el quinto ejemplo que se conoce. Eran piezas que iban sujetas a cotas de malla del ejército cordobés con la función de identificarlas para reintegrarlas al arsenal después de que fueran usadas. Es de la época del califato de Hišām II. The article deals with a new small metal disk with an Arabic inscription incised on it. The study gives the reading and translation of its text and places the object in the Islamic medieval metalwork group it belongs to. It is the fi…
Evidencias de un recubrimiento de magnetita artificial en el armamento íbero
2011
A metallographic study of two pre-roman Iberian arms, affected by a cremation process, revealed the presence of an outer magnetite layer, providing highly protective properties. This layer is extraordinarily tenacious and of very homogeneous thickness, indicating an intentional manufacturing process rather than an accidental formation during the severe heating/cooling cycles the artefact suffered. Up to date, the intentional production of these types of layers has been attributed to a welding process of three different metallic sheets, here an alternative model is proposed, allowing, as could be simulated in the laboratory, the virtually exclusive formation of a magnetite coating.<br>…
Predicting the equilibrium bed slope in natural streams using a stochastic model for incipient sediment motion
2011
In this paper, a method to predict the equilibrium bed slope in natural streams based on the incipient motion criterion is proposed. The method is based on the criterion suggested by Gessler to simulate the grain size distribution of the armour coat using the concept of critical shear stress of a sediment mixture. In particular, a different expression of the probability for a single particle size to be part of the armour coat is firstly proposed; then, a simple two-steps criterion is suggested to estimate the safety factor required by the proposed approach. The method is applied in three different Italian regions (Calabria, Basilicata, and Tuscany) and required several field campaigns invol…
Shoreline Evolution and Environmental Changes at the NW Area of the Gulf of Gela (Sicily, Italy)
2021
Coastal areas are among the most biologically productive, dynamic and valued ecosystems on Earth. They are subject to changes that greatly vary in scale, time and duration and to additional pressures resulting from anthropogenic activities. The aim of this work was to investigate the shoreline evolution and the main environmental changes of the coastal stretch between the towns of Licata and Gela (in the Gulf of Gela, Sicily, Italy). The methodology used in this work included the analysis of: (i) shoreline changes over the long- and medium-term periods (1955–2019 and 1989–2019, respectively), (ii) dune system fragmentation and (iii) the impact of coastal structures (harbours and breakwaters…
A Model for the Study of Sheath Currents in Medium Voltage Cables for Industrial Application
2020
In this paper, the implementation of a simulation model for studying the effect of cross-bonding of metallic sheaths and/or non-magnetic armor of single-core medium voltage cables in the same circuit is discussed. With the use of single-core cables, the resistive losses due to the induced circulating currents in cable sheaths or armors causes an increase of cable temperature that reduces its ampacity. In addition, the risk of electric shock due to induced voltages may be present if a person is exposed to the armor/sheath at the unbounded end. For this reason, special bonding techniques are used to significantly reduce these currents. The authors have implemented a model that could be used t…
Decadal evolution of coastline armouring along the Mediterranean Andalusia littoral (South of Spain)
2016
Abstract Emplacement of hard coastal defence structures, such as seawalls, revetments, groins and breakwaters, or even ports, harbours and marinas, is commonly known as coastline armouring. This paper deals with coastal armouring evolution along the 546 km Mediterranean coast of Andalusia (Spain). It is based on photo interpretation and GIS tools, which have been employed to map coastal structure emplacement and evolution by analysis of 1956, 1977, 2001 and 2010 aerial photos. Additionally the coefficient of infrastructural impact K , which represented the relation between the total length of maritime structures and the length of the study coastal section, was obtained - i.e. minimal at 0.0…
The mediterranean coast of Andalusia (sw spain): the impacts of human coastal structures
2015
Spanish coasts, especially the Andalusia Mediterranean one, were affected over time by progressive urbanization and associated construction of defense structures. Such structures protected small coastal sectors but at places triggered processes of coastal erosion and associated degradation of habitats and ecosystems. A correct management of coastal areas must be based on the monitoring of coastal evolution and human pressure. A useful tool to evaluate the level of human anthropization is the estimation of the "Coastal Armouring", e.g. the quantification of coastal defense structures, infrastructures, ports, etc. In this study, available aerial photographs and satellite images from 1956 to 2…