Results of the test of a pair of 20 kA HTS currents leads

A new series connected 25 T hybrid magnet system is being set up by the Helmholtz Zentrum Berlin (HZB) for neutron scattering experiments. CRPP has designed and manufactured a pair of 20 kA current leads for the powering of the outer superconducting coils of the hybrid magnet system. In connection with the test of joints for JT60SA, the current leads were tested at ENEA at low voltage up to a current of 18 kA. The mass flow rates required to cool the current leads at different currents measured in the test are in line with the design calculations. For the sum of the resistances of the warm and cold end copper contacts of the HTS module values of 13 (Lead A) and 11 n Omega (Lead B) were measured. In addition, the helium flow through the heat exchanger part was stopped at 10 and 12 kA to study the behaviour of the current leads in case of a loss of flow. The time elapsed between stopping of the helium mass flow and the initiation of a quench was found to be 117 s (Lead A) and 125 s (Lead B) compared to a calculated value of 86 s. The lower value obtained by the calculation can be attributed to the lower initial temperatures in the experiment

Analysis of macrobenthic communities in the river basins of Central Italy

The macrobenthic communities of many river basins of Central Italy were sampled and analysed with the Extended Biotic Index, modified for Italian rivers (I.B.E.); 101 watercourses of various typologies were sampled and the total number of taxa detected was 130, among which 117 were useful for the determination of the I.B.E. A preliminary analysis was performed in order to determine the correlation between the frequencies of the different Systematic Units (S.U.) and the I.B.E. values. The data were processed in order to develop an index, the Survey Frequency Index (S.F.I.), which computes the presence of a single S.U. at a given I.B.E. score, in relation to the number of sampling sites showing the same score (I = Ay/nBy). The presence of a faunal group - Index of Group Presence (I.G.P.) - and of taxon - Index of Taxon Presence (I.T.P.) - was evaluated estimating the average of the mean families and the taxon presence respectively. The comparison between the autoecology of a given taxon and its relative I.B.E. and Quality Class (Q.C.) index value provides a preliminary interpretation of a reference community structure within a watershed. The analysis of the macrobenthic community has revealed abnormal distributions of some taxa in relation to the water quality in all of the considered river bio-typologies. In particular, some taxa (i.e. Isoperla, Hydropsychidae, Rhyacophilidae and Ephemerella) have showed higher adaptation levels than expected by the I.B.E. scores. This first contribution has underlined the importance of the disposal of basic elements on the autoecology of single indicative taxa for a critical approach on the composition of the reference communities and the ecotypes identification.Las comunidades macrobentónicas de varias cuencas de Italia Central fueron analizadas mediante el método del Índice Biológico Extendido modificado para los rios italianos (I.B.E.). Fueron realizados muestreos en 101 cursos de agua de diferente tipología y el número total de taxones identificados fue 130, de los cuales 117 fueron utilizados para calcular el índice I.B.E. Un análisis fue realizado para determinar la correlación entre las frecuencias de las Unidades Sistemáticas (U.S.) y los valores de I.B.E. Los datos fueron procesados para desarrollar un índice, el Survey Frequency Index (S.F.I.) que considera la presencia de cada U.S. en cada valor de I.B.E. y con relación al número de estaciones de muestreo que presentan la misma puntuación (I=Ay/nBy). Las presencias de grupo faunístico -Índice de grupo (I.G.P.)- y de taxón -Índice de Presencia de Taxón (I.T.P.)- han sido evaluadas calculando las presencias medias de las familias y de los taxones respectivamente. La comparación entre la autoecología de cada taxón y los valores de I.B.E. y las respectivas Clases de Calidad ofrece una interpretación preliminar de la estructura de la comunidad de referencia dentro de la cuenca. El análisis de las comunidades macrobentónicas ha mostrado distribuciones anormales de varios taxones con relación a la calidad del agua en todas las bio-tipologías consideradas. En particular, algunos taxones (por ejemplo Isoperla, Hydropsichidae, Rhyacophilidae y Ephemerella) evidencian niveles de adaptación más elevados de lo que se esperaba según los valores obtenidos de I.B.E. Este trabajo demuestra la importancia de utilizar los elementos de autoecología de los taxones para establecer las comunidades de referencia y la identificación de los ecotipos

Biological quality of running waters in protected areas: the influence of size and land use

There are still substantial questions about whether protected areas affect the quality and biodiversity of surface waters within their borders. In this study, the size and land use of 19 protected areas of Latium Region (central Italy) were related to the biological quality of 32 streams running inside them. Additionally, the biological quality of 18 out of the 32 streams was compared with the quality recorded on the same streams outside the boundaries of the protected areas. The biological quality was assessed using the Extended Biotic Index, which indicates the macroinvertebrate community health. The quality of 32 study streams running through the protected areas was not related to the size of these areas, but it did reflect land use. On average, the 18 study sites inside protected areas had biological quality similar to external control sites. In the protected areas, the biological quality of streams was higher than for the same streams in the surrounding territory provided that anthropogenic changes were fewer. These data indicate that the creation of protected areas per se does not increase freshwater biodiversity and that land use has a major impact on the biological quality of the stream in a protected area. As a consequence, a higher number of reserves or landscape designations specifically created for aquatic conservation is necessary and recovery programs aimed at restoring physical habitats and reducing sources of impact to aquatic life have to be pursued. Also, where the anthropogenic impact is high (e.g., as in the case of strongly urbanised areas), the creation of effective protected areas might improve the biological quality of water courses

Acque correnti in ambiente urbano: il parco regionale dell'Appia Antica di Roma

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Freshwater quality in urban areas: a case study from Rome, Italy

Water quality in streams running in urban areas can be strongly altered by the impact of human activities. Different kinds of water quality degradation were investigated in the streams running in the 'Appia Antica' Regional Park, placed in the southern suburbs of Rome. Water quality was assessed in 21 sampling points located in eight streams by the analysis of chemical [chemical oxygen demand (COD), nitrates, ammonia, total phosphorus], biological (IBE index), microbial (total coliforms, faecal coliforms, Escherichia coli, faecal streptococci, sulphite-reducing clostridia) ecosystemic (IFF index), and hydrological (flow) parameters. On the whole the results indicate an in depth degradation of water quality. However, IBE and IFF showed local condition of water stress that were not individuated by chemical parameters. A multidisciplinary approach is necessary to highlight the different pressures on water quality of urban freshwaters. The presence of buffer zones in urban green areas does not avoid the impact arising from the surrounding urban area, (C) 2004 Elsevier B.V. All rights reserved

Electromechanical Characterization of Advanced Internal-Tin Nb3Sn Strands for the DTT Magnet System

This paper presents a practical parameterization of the critical surface of the 0.82-mm diameter Nb 3 Sn strands used for the Toroidal Field coils of the Italian Divertor Tokamak Test Facility. The critical current has been measured by means of a Walters Spring device as a function of uniaxial applied strain (±0.5% intrinsic strain) at different field (up to 14 T) and in the temperature range comprised between 4.5 K and 10 K. The experimental results have been analyzed in the framework of the ITER-2008 parameterization and the Extrapolative Scaling Expression, by using a multi-step approach for the data fitting. The accuracy of the scaling laws provides an accurate parameterization of the critical surface in terms of field, temperature and strain, to be used for the characterization and production follow-up of the DTT qualification samples and coils

Results of the test of a pair of 20 kA HTS current leads

A new series connected 25 T hybrid magnet system is being set up by the Helmholtz Zentrum Berlin (HZB) for neutron scattering experiments. CRPP has designed and manufactured a pair of 20 kA current leads for the powering of the outer superconducting coils of the hybrid magnet system. In connection with the test of joints for JT60SA, the current leads were tested at ENEA at low voltage up to a current of 18 kA. The mass flow rates required to cool the current leads at different currents measured in the test are in line with the design calculations. For the sum of the resistances of the warm and cold end copper contacts of the HTS module values of 13 (Lead A) and 11 nOhm (Lead B) were measured. In addition, the helium flow through the heat exchanger part was stopped at 10 and 12 kA to study the behaviour of the current leads in case of a loss of flow. The time elapsed between stopping of the helium mass flow and the initiation of a quench was found to be 117 s (Lead A) and 125 s (Lead B) compared to a calculated value of 86 s. The lower value obtained by the calculation can be attributed to the lower initial temperatures in the experiment