26 research outputs found
Grain size reduction strategies on Eurofer
One of the options currently taken into account for the realization of the first DEMO reactor is the "water-cooled blanket". This option implies a minimum irradiation temperature for the blanket material in the range of 280–350 °C. In addition to the DBTT (Ductile to Brittle Transition Temperature) shift due to the DPA (displacement per atom) damage under irradiation, also the issue of the increased embrittlement due to He production must be taken into account. This issue appears even more detrimental and less manageable because the DBBT shift due to the Helium production does not saturate with the dose, as it results from previous works reported in literature. The experimental results and the difference in behaviour between ODS (Oxide Dispersion Strengthened Steels) RAFM (Reduced Activation Ferritic Martensitic) and other FM (Ferritic Martensitic) alloys (EM10, P91) showed that it is possible to improve the resistance to He embrittlement by both intra-granular precipitation of Y-Ti oxides and by decreasing the grain size at the same time. Nevertheless, anyway, the multiplication of the grain boundaries increases the dilution of He on grain surface, delaying the formation of He bubbles on grain boundaries and, therefore, the susceptibility to the He embrittlement. Several grain size reduction strategies have then been investigated on EUROFER both at the austenitization stage, on the PAGS (Prior Austenite Grain Size), and at the tempering stage, on the tempered martensite. The microstructural observations have been carried out by means of SEM (Scanning Electron Microscopy). Also the effect of grain size reduction on the toughness of the material will be taken into account; The DBTTs resulting from impact tests on KLST specimens will be shown. The outcomes of the microstructural observations, as well as the preliminary mechanical characterization (impact tests) will be discussed in this paper. Keywords: EUROFER 97, RAFM steels, Microstructure, Multiple normalization, Asymmetric rolling, Recrystallization, KLS
Stupratore e vittima. Schemi di tipizzazione e variabili socio-culturali in un confronto fra Glasgow e Firenze
A remotely operated FIMEC apparatus for the mechanical characterization of neutron irradiated materials
From Flat-top Cylinder Indenter for Mechanical Characterization (FIMEC) test yield stress and tensile strength can be obtained. Results regarding different materials, most of them of fusion interest, show the general validity of the method. Moreover, indication on the ductile to brittle transition temperature (DBTT) of martensitic steels has been drawn by performing tests at different temperatures. FIMEC offers the possibility to perform several tests on a small volume of material, e.g. it has been estimated that 18 indentations can be made on a single disk (Phi = 25 mm, h = 5 mm), For this reason, its application is of interest to characterize materials irradiated in the future IFMIF or in other sources. with a limited irradiation volume. A remotely operated apparatus has been designed and costructed to work in hot cell on irradiated samples. It employs a WC punch (Phi = 1 mm) and can operate at temperatures in the range between -180 degrees C and +200 degrees C. Details of the apparatus are presented. (C) 1998 Elsevier Science B.V. All rights reserved
Distribution, ecology, and status of the white shark, Carcharodon carcharias, in the Mediterranean Sea
The occurrence of the white shark, Carcharodon carcharias, in the Mediterranean Sea has been reported since the Middle Ages (476–1453). Several studies have documented its presence in various areas of the basin, but no comprehensive review of the distribution and status of this species is available for the area. We compiled a total of 628 white shark records from 476 to 2015. Data suggests that the white shark is more common in the western Mediterranean Sea, especially in the Adriatic Sea and in the Sicilian Channel and is more frequently observed during summer months. However, analysis using night-time satellite imagery showed the existence of an anthropogenic bias in the distribution of white sharks. All size classes have been recorded in the region. However, the highest occurrence of young of the year has been recorded in the Sicilian Channel, in the Adriatic Sea and in the Aegean Sea, in summer, suggesting these areas might serve as nursery grounds. In the Mediterranean Sea, the white shark exhibits a broad diet. The most common prey found include small cetaceans (Tursiops truncatus, Stenella coeruleoalba), tuna (Thunnus spp.), swordfish (Xiphias gladius) and loggerhead sea turtle (Caretta caretta). A total of 53 white shark records refer to interactions between sharks and humans that resulted in a detrimental impact on humans, which include 42 bites and 11 reports of the presence of human remains in the stomach of captured animals. Analysis of the temporal variation in mean total lengths of white sharks found a decreasing trend from 1913 to 2012. The decreasing length of white sharks suggests this species might be declining in the Mediterranean Sea
Co-evolution and financial relationships between the banking system and local industrial community of Prato industrial district (1936-1999) An ecological approach
SIGLEAvailable from British Library Document Supply Centre-DSC:9350.9281(2002-13) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Full scale electrical insulation coating development
A de-mountable mechanical system has been designed by ITER-IT for the attachment and the remote handling of the blanket modules. The modules are attached to the supporting structure by bolting using four flexible radial supports (cartridges) whi
Mechanical characterisation of fusion materials by indentation test
FIMEC is an indentation test, which permits the evaluation of yield and ultimate tensile stress and to draw indication about the ductile to brittle transition temperature. The apparatus has been recently implemented with a feedback system to maintain strictly constant the penetration speed of cylindrical punch during the test. So, experiments performed on several materials, as those :for first wall and blanket, show that the scattering between data from FIMEC and from standard tensile test is reduced within the range +/-0.06; i.e. it is comparable with the scattering obtained in different tensile tests on the same material. A numerical simulation has been carried out to understand the basic mechanism of the process. (C) 2001 Elsevier Science B.V. All rights reserved
Bycatch of large elasmobranchs in the traditional tuna traps (tonnare) of Sardinia from 1990 to 2009
The species composition and extent of large elasmobranch bycatch in the Sardinian tuna trap fisheries have received minimal attention in the primary literature. The Sardinian Large Elasmobranch Database (SLED), a non-governmental project, contains records from direct observations, fishing industry sources and reviews from the literature regarding the extent and composition of large elasmobranch bycatch from the only six tuna traps at six fishing sites (Saline; Capo Testa; Carloforte: Portoscuso; Calasetta; and Portopaglia) from the period of 1990 to 2009. During this time period, 42 bycatch events were documented that were comprised of the incidental capture of 15 Mobulid rays and 27 large sharks representing ten species and seven families (23% of the total elasmobranch species previously reported in Sardinian waters). Even though the low number of collective elasmobranchs captured (n = 42) in this study does not pose a conservation concern several bycatch species considered rare and/or depleted in this region were among the species observed. Mobula mobular was the most abundant elasmobranch species caught, with Alopias vulpinus the most commonly caught shark species. There were differences in the catch per unit effort between the six sites with the highest CPUE occurring in Saline, Carloforte and Porto Paglia. Although the sheer volume and conservation impact of traditional tuna traps on large elasmobranchs is exceeded by other fishing gears in Mediterranean waters, small scale (long term) bycatch monitoring programs are vital when evaluating the presence, biodiversity and conservation of elasmobranchs in previously unstudied areas. (C) 2011 Elsevier B.V. All rights reserved
Distribution, ecology, and status of the white shark, Carcharodon carcharias, in the Mediterranean Sea
The occurrence of the white shark, Carcharodon carcharias, in the Mediterranean Sea has been reported since the Middle Ages (476–1453). Several studies have documented its presence in various areas of the basin, but no comprehensive review of the distribution and status of this species is available for the area. We compiled a total of 628 white shark records from 476 to 2015. Data suggests that the white shark is more common in the western Mediterranean Sea, especially in the Adriatic Sea and in the Sicilian Channel and is more frequently observed during summer months. However, analysis using night-time satellite imagery showed the existence of an anthropogenic bias in the distribution of white sharks. All size classes have been recorded in the region. However, the highest occurrence of young of the year has been recorded in the Sicilian Channel, in the Adriatic Sea and in the Aegean Sea, in summer, suggesting these areas might serve as nursery grounds. In the Mediterranean Sea, the white shark exhibits a broad diet. The most common prey found include small cetaceans (Tursiops truncatus, Stenella coeruleoalba), tuna (Thunnus spp.), swordfish (Xiphias gladius) and loggerhead sea turtle (Caretta caretta). A total of 53 white shark records refer to interactions between sharks and humans that resulted in a detrimental impact on humans, which include 42 bites and 11 reports of the presence of human remains in the stomach of captured animals. Analysis of the temporal variation in mean total lengths of white sharks found a decreasing trend from 1913 to 2012. The decreasing length of white sharks suggests this species might be declining in the Mediterranean Sea