1,721,333 research outputs found
Thirteen facts that you need to know on multiple populations in globular clusters
No full textI review the methods, mostly developed in the last decade, that are commonly used to identify and characterize multiple populations (MPs) in Globular Clusters (GCs) based on photometry. I summarize the results from the recent surveys of MPs with the Hubble Space Telescope (HST) and ground-based facilities and provide a list of the main properties of MPs as inferred from these studies
A Simplified Approach for the Corrosion Fatigue Assessment of Steel Structures in Aggressive Environments
No full text: Fatigue performance is often a key aspect when dealing with existing steel structures such as steel bridges or offshore constructions. This issue proves to be more critical as these structures are usually located in aggressive environments and are thus exposed to progressive degradation. Indeed, disruptive phenomena such as corrosion can severely worsen the fatigue performance of the steel components. Currently, the normative standards do not provide a codified procedure for the fatigue checks of steel structures subjected to ongoing corrosion. Within this framework, in this paper a simplified approach for the life-cycle assessment of corroded steel structures is proposed. For this purpose, the concept of "critical corrosion degree" is introduced, allowing the expression of corrosion fatigue checks in a more direct "demand vs. capacity" form with respect to the currently available methods. A first validation of such methodology is reported for the corrosion fatigue tests drawn from the literature. The predicted levels of critical corrosion are in good agreement with the values of artificially induced corrosion (i.e., 4, 8, and 12% of mass loss, respectively), with a maximum relative error of ≈9.3% for the most corroded specimen. Finally, parametrical analyses are performed, highlighting the influence of the model parameters on the corrosion fatigue performance of the steel elements
“Aspetti tecnico economici nell’utilizzo di sorgenti artificiali miste negli impianti di illuminazione per interni”
No full textAdvanced Fatigue Assessment of Riveted Railway Bridges on Existing Masonry Abutments: An Italian Case Study
No full textInfluence of camming imperfections on the resistance of lap shear riveted connections
No full textTo investigate its influence on the resistance of lap shear hot-driven riveted connections, a parametric study has been carried out by means of Finite Element (FE) simulations. The examined parameters are the number and the diameter of rivets, the number of shear surfaces, the dimensions of connected plates and the magnitude and orientation of the camming defect. The dimensions of the connections have been selected to be representative of the common details of existing riveted constructions and the FE models have been calibrated against previous experimental tests. The obtained results allowed characterizing in which terms the magnitude and the orientation of the camming defect affect the resistance and failure mode of the connections. In addition, an empirical formula has been derived to predict the resistance of lap shear riveted connections with camming imperfection and its accuracy has been statistically assessed in accordance with EN1990
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