Assessment of digital image correlation measurement errors: methodology and results

Optical full-field measurement methods such as Digital Image Correlation (DIC) are increasingly used in the field of experimental mechanics, but they still suffer from a lack of information about their metrological performances. To assess the performance of DIC techniques and give some practical rules for users, a collaborative work has been carried out by the Workgroup “Metrology” of the French CNRS research network 2519 “MCIMS (Mesures de Champs et Identification en Mécanique des Solides / Full-field measurement and identification in solid mechanics, http://www.ifma.fr/lami/gdr2519)”. A methodology is proposed to assess the metrological performances of the image processing algorithms that constitute their main component, the knowledge of which being required for a global assessment of the whole measurement system. The study is based on displacement error assessment from synthetic speckle images. Series of synthetic reference and deformed images with random patterns have been generated, assuming a sinusoidal displacement field with various frequencies and amplitudes. Displacements are evaluated by several DIC packages based on various formulations and used in the French community. Evaluated displacements are compared with the exact imposed values and errors are statistically analyzed. Results show general trends rather independent of the implementations but strongly correlated with the assumptions of the underlying algorithms. Various error regimes are identified, for which the dependence of the uncertainty with the parameters of the algorithms, such as subset size, gray level interpolation or shape functions, is discussed

Fathers' and Mothers' Involvement in Parental Tasks : An Unequal Division

This chapter looks at the division of parental tasks by focusing on the gender relations at play both in the parents' generation, as they tie in with other social relations approached through demographic and socioeconomic characteristics (age differences between partners, educational level, occupation, income, work time, etc.), and between parents and children. The aim is to verify whether, in addition to gender relations in the parental couple, family composition - number, age and especially gender of the children - an influence on fathers' and mothers' day-to-day involvement in childcare. Less involved in routine daily tasks, fathers still appear to be secondary players in the education and care of their children. Paternal investment varies according to the types of task involved, however (dressing the children, putting them to bed, taking them places, leisure activities and homework), and according to the characteristics of the couple and the children. Questions of identity and gender relations within the family thus explain the persistently wide gender gap in parental involvement