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Mismatch in early life traits between settlers and recruits in a Mediterranean fish: clue of the relevance of the settlement tail?

100%

Di Franco A. , Gianni F. , Guidetti P.

Acta Ichthyologica et Piscatoria

2015

tom 45

nr 2

Background. Life stage transitions (e.g., settlement and recruitment), characterized by high mortality rates, act as selective bottlenecks for fishes with a bipartite life cycle. Mortality at these stages is usually selective and potentially affected by larval history. This process is reflected in an inconsistency in larval traits’ distribution between subsequent life stages (e.g., settlers and recruits) originating from the same reproductive season. Despite the importance of this issue only very scarce information is available about this aspect of Mediterranean fishes life histories. Materials and Methods. Here we described settlement and investigated the match/mismatch of larval traits between settlers and recruits coming from the same reproductive season, using the white seabream, Diplodus sargus sargus (Linnaeus, 1758), as a model species along ~ 200 km of the Apulian Adriatic coast (south-western Adriatic Sea, Italy). Both microstructure and chemistry analyses were carried out on otoliths of settlers (n = 140) and recruits (n = 113). Results. We highlighted a mismatch in two life traits, i.e., PLD (pelagic larval duration) and natal origin, between settlers and recruits. Recruits showed PLD longer than the maximum recorded for settlers, and a higher number of natal sources compared to settlers. Mismatch in PLD could suggest selective juvenile mortality related to PLD, and recruits with higher PLD potentially originated from the settlement tail (i.e., settled after the settlement peak). Conclusion. Our findings can support hypotheses suggesting that 1) a fraction of juveniles are selectively eliminated; 2) settlement tail could play a relevant role in replenishing local populations of white seabream.

Synergic computational and experimental development of a cast iron crankshaft for high performance automotive diesel engine

75%

Peirano R. , Barbato S. , Ceronetti G. , Di Franco A. , Golisano R. , Vassallo A.

Silniki Spalinowe

2007

tom R. 46, nr SC1

98-110

In order to achieve consistent cost reduction, an extensive and simultaneous experimental and computational activity has been performed within GM Powertrain Europe (GMPT-E) with the aim of substituting a steel crankshaft with a cast iron one in a high performance automotive diesel engine, as described in this paper. By means of a preliminary simulation analysis the most critical sections of the crankshaft have been identified andsubsequently strain-gauges have been installed in such locations on a prototype crankshaft. This latter has been then installed on a firing engine in order to provide bending and torsion stresses on the selected points, so to correlate the crankshaft mathematical model outputs with actual results. The following step has been to run a more detailed simulation, by using the calibrated finite element model of the crankshaft, in the framework of a multi-body analysis, with the aim of assessing the crankshaft fatigue behaviour. A key feature of the above described approach is the ability to set-up a reliable mathematical model to be extensively applied for Virtual Validation, by means of DOE (Design Of Experiment), FLP (Fatigue Life Prediction) and DFSS (Design For Six Sigma) approaches, aimed at assuring a final robust design of the crankshaft. The activities described above, together with GM standard components reliability verification, demonstrated the feasibility of this cost reduction initiative and provided a powerful design and validation technique in the framework of the ongoing migration from "road to rig to math".