A Fuzzy Decision Tree for Fault Classification

In plant accident management, the control room operators are required to identify the causes of the accident, based on the different patterns of evolution of the monitored process variables thereby developing. This task is often quite challenging, given the large number of process parameters monitored and the intense emotional states under which it is performed. To aid the operators, various techniques of fault classification have been engineered. An important requirement for their practical application is the physical interpretability of the relationships among the process variables underpinning the fault classification. In this view, the present work propounds a fuzzy approach to fault classification, which relies on fuzzy if-then rules inferred from the clustering of available preclassified signal data, which are then organized in a logical and transparent decision tree structure. The advantages offered by the proposed approach are precisely that a transparent fault classification model is mined out of the signal data and that the underlying physical relationships among the process variables are easily interpretable as linguistic if-then rules that can be explicitly visualized in the decision tree structure. The approach is applied to a case study regarding the classification of simulated faults in the feedwater system of a boiling water reactor.     

Bayesian inference for power law processes with applications in repairable systems

Statistical models for recurrent events are of great interest in repairable systems reliability and maintenance. The adopted model under minimal repair maintenance is frequently a nonhomogeneous Poisson process with the power law process (PLP) intensity function. Although inference for the PLP is generally based on maximum likelihood theory, some advantages of the Bayesian approach have been reported in the literature. In this paper it is proposed that the PLP intensity be reparametrized in terms of (β,η), where β is the elasticity of the mean number of events with respect to time and η is the mean number of events for the period in which the system was actually observed. It is shown that β and η are orthogonal and that the likelihood becomes proportional to a product of gamma densities. Therefore, the family of natural conjugate priors is also a product of gammas. The idea is extended to the case that several realizations of the same PLP are observed along overlapping periods of time. Some Monte Carlo simulations are provided to study the frequentist behavior of the Bayesian estimates and to compare them with the maximum likelihood estimates. The results are applied to a real problem concerning the determination of the optimal periodicity of preventive maintenance for a set of power transformers. Prior distributions are elicited for β and η based on their operational interpretation and engineering expertise.     

Disability and work intensity in Italian households

Review of Economics of the Household - The 2030 Agenda of the United Nations clearly sets the inclusion of persons with disabilities in the labour market as a main goal. However, especially in care...     

Social Capital is Associated with Earnings among Foreign‐born Mexican Men but not Women in Los Angeles County

The mechanisms through which social capital is accumulated may influence its relationship with hourly earnings. Because Mexican men and women accumulate social capital differently, for instance, gender may be an important factor for understanding social capital’s association with Mexican migrant earnings. Unlike past research that often fails to differentiate between various social capital metrics (e.g., social network member reciprocity, participation in civic group organizations, neighbourhood trust), this article estimates two of these associations with wages while controlling for individual‐, household‐ and neighbourhood‐level characteristics. Results suggest that foreign‐born Mexican men receive a wage premium from civic participation (bridging social capital) and a wage penalty from reciprocal social network exchange (bonding social capital). We also find that unauthorized legal status (among Mexican men and all migrants) and having children (among women) were negatively associated with hourly wages. We conclude with a discussion of the relative association of human and social capital with Mexican migrant wages.     

Ranking and Prioritization of Emergency Departments Based on Multi-indicator Systems

In this work we discuss how Emergency Departments (EDs) can be ranked on the basis of multiple indicators. This problem is of absolute relevance due to the increasing importance of EDs in regional healthcare systems and it is also complex as the number of indicators that have been proposed in the literature to measure ED performance is very high. Current literature faces this problem using synthetic (or numerically aggregated) indicators of a set of performance measures but, although simple, this solution has a number of drawbacks that make this choice inefficient: a compensation effect among the indicators; a high degree of subjectivism in the indicators weighting; opacity in the decision making; all the EDs are considered to be comparable. Indeed, the situations in which EDs are comparable (i.e. when all the performance of one ED are not lower than the performance indicators of the other) are a minority and incomparability is by itself a source of information that should be used to identify situations for which different policy actions should be designed. In this work we propose to use non compensatory composite indicators and partial ordering theory to rank and compare EDs giving value to the reasons of such an incomparability. These methods are applied on a case study of 19 EDs in an administrative region in Italy.     

RELATIONSHIP LENDING DURING A FINANCIAL CRISIS

This paper studies whether relationship lending mitigates the transmission of the Lehman default shock to the supply of credit in Italy. Exploiting the presence of multiple banking relationships, we control for banks' and firms' unobserved characteristics. Results show that the growth of credit itself is higher and its cost lower the shorter the distance between the bank and the firm, the longer the relationship, and the higher the share of credit held by the bank. Credit growth by relationship lenders is 4.6% higher than that by transactional lenders; the increase in the cost of credit is 50 basis points lower. The positive effect of relationship lending on credit supply increased during the crisis, compared to a pre‐crisis period. The beneficial effect of relationship lending is weaker if the relationship lender is more exposed to the financial crisis, especially when lending to weaker borrowers.     

Asymptotic relative efficiency of score tests in Weibull models with measurement errors

The main object of this paper is to discuss properties of the score statistics for testing the null hypothesis of no association in Weibull model with measurement errors. Three different score statistics are considered. The efficient score statistics, a naive score statistics obtained by replacing the unobserved true covariate with the observed one and a score statistics based on the corrected score statistics. It is shown that corrected and naive score statistics are equivalent and the asymptotic relative efficiency between naive and efficient score statistics is derived.     

The Role of Proactive Coping Strategies,Time Perspective,Perceived Efficacy on Affect Regulation,Divergent Thinking and Family Communication in Promoting Social Well-Being in Emerging Adulthood

The study analyzed the influence of time perspective, proactive coping strategies, perceived self-efficacy in affect regulation, divergent thinking and perceived quality of family communication on social well-being in a sample of 232 emerging adults. Social well-being showed positive correlations with proactive coping strategies, future-oriented time perspective, expression of positive emotions and regulation of negative emotions, divergent thinking, open communication with parents. A problematic family communication and a present-oriented time perspective were negatively correlated with social well-being. A forward Ridge step-wise regression model was conducted, evidencing four significant positive predictors of social well-being: proactive coping, perceived efficacy in affect regulation and open communication with parents; on the contrary, present oriented time perspective contributes significantly but negatively to social well-being.