A new approach for evaluation of risk priorities of failure modes in FMEA

This paper presents a method for carrying out the calculus of the risk priority of failures in Failure Mode and Effect Analysis (FMEA). The novelty of the method consists of new management of data provided by the design team, normally given on qualitative scales, without necessitating an arbitrary and artificial numerical conversion. The practical effects of these issues are shown in an application example

Composition laws for learning curves of industrial manufacturingprocesses

The theory of learning curves is widely investigated in many fields related to production planning, quality improvement and cost analysis. Many different approaches to describe the learning mechanism of a process are reported in the academic literature. The aim is to analyse the behaviour of complex systems composed of a network of elementary processes whose learning curve is known. Composition laws of two basic aggregation structures, series and parallel, are discussed and analysed. The effects of these composition laws are shown in a series of practical examples

Qualitative ordinal scales: the concept of ordinal range

Many practical problems of quality control involve the use of ordinal scales. Questionnaires planned to collect judgments on qualitative or linguistic scales, whose levels are terms such as "good," "bad," "medium," etc., are extensively used both in evaluating service quality and in visual controls for manufacturing industry. In an ordinal environment, the concept of distance between two generic levels of the same scale is not defined. Therefore, a population (universe) of judgments cannot be described using "traditional" statistical distributions since they are based on the notion of distance. The concept of "distribution shape" cannot be defined as well. In this article, we introduce a new statistical entity, the so-called ordinal distribution, to describe a population of judgments expressed on an ordinal scale. We also discuss which of the traditional location and dispersion measures can be used in this context and we briefly analyze some of their properties. A new dispersion measure, the ordinal range, as an extension of the cardinal range to ordinal scales, is then proposed. A practical application in the field of quality is developed throughout the articl

A New Forecasting Model for the Diffusion of ISO 9000 Standard Certifications in European Countries

ISO 9000 standards for quality system management are involving a higher and higher number of enterprises and organizations. This paper presents a detailed analysis of certification diffusion in Italy and in some European countries with similar economic structures. Benchmarking and evolution forecasts are based on the "logistic model", traditionally used for studying biological growth phenomena. The presentation is supported by many empirical data, which show that, in many countries, the phenomenon is going to be close to saturation. Finally, some considerations about new developments, after the present "certification era", are proposed

Cumulative individual seed production in the polycarpic Caesalpinia gilliesii (Fabaceae): effects of temporal variability in floral display, plant density and pollination

In polycarpic species, floral display size and density of conspecific neighbours are time variable as well as their effects on pollination and fecundity. Here, we address how individual pollinator-dependent seed production responds to changes in floral display size and the density of flowering conspecific neighbours. Using path analysis, we disentangle the partial effects of floral display size, the density of flowering neighbours and pollination intensity on the total seed output of the partially self-compatible shrub Caesalpinia gilliesii during three consecutive reproductive seasons. We also modelled the effects of temporal variability in floral offer and pollination intensity (as the coefficient of variation) on cumulative seed production over the study period. Floral display size had either positive or negative effects on pollination intensity in different reproductive seasons, but conspecific density had no significant effect within each season. However, cumulative seed production increased under lower temporal variability in conspecific density. Our results suggest that, because of the dynamic nature of floral offer in a polycarpic species, the temporal changes in floral display size and density may counteract each other reducing the risk of successive pollination failures and increasing seed production over time.Fil: Calviño, Ana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Ashworth, Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Galetto, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin