Giancarlo Raiteri

Analysis of surface circulation structures along a frequently repeated XBT transect crossing the Ligurian and Tyrrhenian Seas

A dataset of XBT (eXpendable BathyThermograph) temperature profiles collected by ships of opportunity along the Genova–Palermo route, since September 1999, is analyzed, together with altimetric observations and model results, with the purpose of identifying and characterizing robust circulation features along the track and investigating their variability. An anticyclone is found in the Ligurian Sea, just north of the Corsica Channel, not present in previous descriptions of the Mediterranean Sea circulation. It appears to be a recurrent feature, better defined and stronger in summer and in the beginning of autumn. In the northern part of the Tyrrhenian Sea, the well-known Bonifacio dipole shows a similar seasonality, in agreement with previous observations. However, the Bonifacio anticyclone also displays a strong interannual variability, not previously recorded, with significant variations in position and shape. In fact, the data suggest the existence of two distinct summer circulation regimes related to the position and shape of the Ligurian anticyclone. When the latter is wider, filling the entire region north of the Corsica Channel, the circulation in the northern Tyrrhenian Sea is isolated from that in the Ligurian Sea, in agreement with the common picture. However, the altimeter maps show that there are several cases in the last two decades in which the Ligurian anticyclone is small and displaced to the west, allowing an inflow through the Corsica Channel into the Tyrrhenian Sea. The two regimes appear to result from a delicate balance between the forcings acting in the two sub-basins and the topographic constraints.

Estimate of compressive strength of an unidirectional composite lamina using cross-ply and angle-ply laminates

In this work has been estimated the compressive strength of a unidirectional lamina of a carbon/epoxy composite material, using the cross-ply and angle-ply laminates. Over the years various methods have been developed to deduce compressive properties of composite materials reinforced with long fibres. Each of these methods is characterized by a specific way of applying load to the specimen. The method chosen to perform the compression tests is the Wyoming Combined Loading Compression (CLC) Test Method, described in ASTM D 6641 / D 6641M-09. This method presents many advantages, especially: the load application on the specimen (end load combined with shear load), the reproducibility of measurements and the experimental equipment quite simplified. Six different laminates were tested in compressive tests. They were realized by the same unidirectional prepreg, but with different stacking sequences: two cross-ply [0/90]ns, two angle-ply [0/90/±45]ns and two unidirectional laminates [0]ns and [90]ns. The estimate of the compressive strength of the unidirectional laminates at 0°, was done by an indirect analytical method, developed from the classical lamination theory, and which uses a multiplicative parameter known as Back-out Factor (BF). The BF is determined by using the experimental values obtained from compression tests.

Assessment of Quality and Reliability of Measurements with XBT Sippican T5 and T5/20

AbstractThe T5 expendable bathythermographs reach the greatest depth within the current XBT family. Since the early 1970s, in several areas they have been providing a significant part of available ...