Incidence of Pitting Corrosion Wastage on the Hull Girder Ultimate Strength

AbstractThe paper focuses on the assessment of the hull girder ultimate strength, combined with random pitting corrosion wastage, by the incremental-iterative method. After a brief review about the state of art, the local ultimate strength of pitted platings under uniaxial compression is preliminarily outlined and subsequently a closed-form design formula is endorsed in the Rule incremental-iterative method, to account for pitting corrosion wastage in the hull girder ultimate strength check. The ISSC bulk carrier is assumed as reference ship in a benchmark study, devoted to test the effectiveness of the incremental-iterative method, by a comparative analysis with a set of FE simulations, performed by Ansys Mechanical APDL. Four reference cases, with different locations of pitting corrosion wastage, are investigated focusing on nine combinations of pitting and corrosion intensity degrees. Finally, a comparative analysis between the hull girder ultimate strength, combined with pitting corrosion wastage, and the relevant values, complying with the Rule net scantling approach, is performed. Based on current results, the modified incremental-iterative method allows efficiently assessing the hull girder ultimate strength, combined with pitting corrosion wastage, so revealing useful both in the design process of new vessels and in the structural health monitoring of aged ships

Comparative analysis among deterministic and stochastic collision damage models for oil tanker and bulk carrier reliability

Abstract The incidence of collision damage models on oil tanker and bulk carrier reliability is investigated considering the IACS deterministic model against GOALDS/IMO database statistics for collision events, substantiating the probabilistic model. Statistical properties of hull girder residual strength are determined by Monte Carlo simulation, based on random generation of damage dimensions and a modified form of incremental-iterative method, to account for neutral axis rotation and equilibrium of horizontal bending moment, due to cross-section asymmetry after collision events. Reliability analysis is performed, to investigate the incidence of collision penetration depth and height statistical properties on hull girder sagging/hogging failure probabilities. Besides, the incidence of corrosion on hull girder residual strength and reliability is also discussed, focussing on gross, hull girder net and local net scantlings, respectively. The ISSC double hull oil tanker and single side bulk carrier, assumed as test cases in the ISSC 2012 report, are taken as reference ships

Influence of High-Productivity Process Parameters on the Surface Quality and Residual Stress State of AISI 316L Components Produced by Directed Energy Deposition

The production of large components is one of the most powerful applications of laser powder-directed energy deposition (LP-DED) processes. High productivity could be achieved, when focusing on industrial applications, by selecting the proper process parameters. However, it is of crucial importance to understand the strategies that are necessary to increase productivity while maintaining the overall part quality and minimizing the need for post-processing. In this paper, an analysis of the dimensional deviations, surface roughness and subsurface residual stresses of samples produced by LP-DED is described as a function of the applied energy input. The aim of this work is to analyze the effects of high-productivity process parameters on the surface quality and the mechanical characteristics of the samples. The obtained results show that the analyzed process parameters affect the dimensional deviations and the residual stresses, but have a very little influence on surface roughness, which is instead dominated by the presence of unmelted particles

On the quality of unsupported overhangs produced by laser powder bed fusion

One of the main design constraints for additive manufacturing is the definition of downward-facing surfaces, which can lead to problems, like part failing or warping, during construction and poor surface quality. In this paper, a specific index has been defined to represent the surface quality of the downward-facing surfaces induced by the laser powder bed fusion (L-PBF) process. In order to validate the quality index, a design of experiment (DoE) that considers geometric parameters of the overhangs has been defined and carried out, and the quality of resulting surfaces has been evaluated using an optical scanning system. The statistical analysis (ANOVA) has allowed identifying the relationships between significant geometrical parameters and the quality index here proposed

Predicting sense of community and participation by applying machine learning to open government data

Community capacity is used to monitor socio-economic development. It is composed of a number of dimensions, which can be measured to understand the possible issues in the implementation of a policy or the outcome of a project targeting a community. Measuring community capacity dimensions is usually expensive and time consuming, requiring locally organised surveys. Therefore, we investigate a technique to estimate them by applying the Random Forests algorithm on secondary open government data. Our research focuses on the prediction of measures for two dimensions: sense of community and participation. The most important variables for this prediction were determined. The variables included in the datasets used to train the predictive models complied with two criteria: nationwide availability; sufficiently fine-grained geographic breakdown, i.e. neighbourhood level. The models explained 77% of the sense of community measures and 63% of participation. Due to the low geographic detail of the outcome measures available, further research is required to apply the predictive models to a neighbourhood level. The variables that were found to be more determinant for prediction were only partially in agreement with the factors that, according to the social science literature consulted, are the most influential for sense of community and participation. This finding should be further investigated from a social science perspective, in order to be understood in depth

Characterization of four typical calabrian cured meat products: Spicy sausage, soppressata, ’nduja and capocollo

Typical Calabrian cured meat products, produced with meat of local and commercial pig breeds were evaluated and characterized for their quality and homogeneity. Sensory, microbiological and physicochemical analyses were carried out at the end of cured meat products ripening. A wide statistical variability was observed in these commercial products due to both company and different productions. The mineral composition was similar to that observed by other authors in similar cured meat products; the statistical analysis revealed only a difference among the samples for magnesium (P<0.01) and for calcium (P<0.05) contents. According to the performed sensory analysis, the meat products were acceptable with some differences due to both production and company variables. About microbial populations, the most abundant were lactic acid bacteria and total aerobic bacteria, while enterobacteria were less represented

QUARE: 1st Workshop on Measuring the Quality of Explanations in Recommender Systems

QUARE - measuring the QUality of explAnations in REcommender systems - is the first workshop that aims to promote discussion upon future research and practice directions around evaluation methodologies for explanations in recommender systems. To that end, we bring together researchers and practitioners from academia and industry to facilitate discussions about the main issues and best practices in the respective areas, identify possible synergies, and outline priorities regarding future research directions. Additionally, we want to stimulate reflections around methods to systematically and holistically assess explanation approaches, impact, and goals, at the interplay between organisational and human values. The homepage of the workshop is available at: https: //sites.google.com/view/quare-2022/

Biological Responses to Cadmium Stress in Liverwort Conocephalum conicum (Marchantiales)

Oxidative damage (production and localization of reactive oxygen species) and related response mechanisms (activity of antioxidant enzymes), and induction of Heat Shock Protein 70 expression, have been studied in the toxi-tolerant liverwort Conocephalum conicum (Marchantiales) in response to cadmium stress using two concentrations (36 and 360 µM CdCl2). Cadmium dose-dependent production of reactive oxygen species (ROS) and related activity of antioxidant enzymes was observed. The expression level of heat shock protein (Hsp)70, instead, was higher at 36 µM CdCl2 in comparison with the value obtained after exposure to 360 µM CdCl2, suggesting a possible inhibition of the expression of this stress gene at higher cadmium exposure doses. Biological responses were related to cadmium bioaccumulation. Since C. conicum was able to respond to cadmium stress by modifying biological parameters, we discuss the data considering the possibility of using these biological changes as biomarkers of cadmium pollution