Simulating scratch behavior of polymers with mesoscopic molecular dynamics

Part replacement and repair is needed in structures with moving parts because of scratchability and wear. In spite of some accumulation of experimental evidence, scratch resistance is still not well understood. We have applied molecular dynamics to study scratch resistance of amorphous polymeric materials through computer simulations. As a first approach, a coarse grain model was created for high density polyethylene at the mesoscale. We have also extended the traditional approach and used real units rather than reduced units (to our knowledge, for the first time), which enable an improved quantification of simulation results. The obtained results include analysis of penetration depth, residual depth and recovery percentage related to indenter force and size. Our results show there is a clear effect from these parameters on the tribological properties. We also discuss a "crooked smile" effect on the scratched surface and the reasons for its appearance.

The effects of place of residence on tourist motivations: a revised case of the Urban Quadrangle of Minho

This study seeks to capture the underlying reasons for the travel decisions of residents of the Urban Quadrangle of Minho (composed of the municipalities of Barcelos, Braga, Guimarães, and Vila Nova de Famalicão). The aim of the research is three-fold. Firstly, the study identifies the push and pull motivational factors of residents of the Urban Quadrangle of Minho. Secondly, the study examines whether there are differences between the tourist motivations of residents of the four different municipalities of the Urban Quadrangle. Finally, the study investigates if there are any differences in the motivations of those who choose national and international destinations. The methodology comprises quantitative research based on questionnaires administered in 2012 to residents of the Urban Quadrangle of Minho. A principal component factor analysis is employed to identify six push and seven pull factors. The comparison of the mean scores of these factors across municipalities and across residents that choose national and international destinations reveals that the most valued and least valued factors are common to all four municipalities and both groups of residents (that choose national and international destinations).

Tourist motivation of the residents of the Urban Quadrilátero of Minho: a gender analysis

Women are increasingly active in the participation and consumption of tourism, representing a strong and unique market segment. Knowledge of the needs and preferences of female tourists represents a key success factor in the tourism industry. This preliminary study seeks to capture the underlying reasons for the travel decisions of the residents of the Urban Quadrilátero of Minho, investigating their tourist motivations from a gendered perspective. Insight on tourism motivation may be an important policy tool for tourism planners and managers in the development of products and marketing strategies. The empirical analysis is undertaken based on questionnaires administered in 2012 to residents of the Urban Quadrilátero of Minho. Preliminary results do not reveal significant gender differences in the importance that the local residents place on various tourism motivation factors.

Use of performance information by local politicians: a field study in the Portuguese context.

This paper seeks to investigate the use of performance information by politicians and whether the institutional reforms on performance management (PM) have been operationalized by local politicians. Differences on the policy field and the organizational context have been analyzed. Our goal is contribute to knowledge on PM in the political sphere and understand the different responses of politicians to government change initiatives (mainly coercive pressures). Our findings show that local politicians support the notion that greater attention should be devoted to the use of performance information on the evaluation process. Nevertheless they are very skeptic in relation to effective execution of government reforms. There is an internal culture where agencies are embedded, strongly influenced by the high degree of politicisation among senior managers, that lead politicians to be more concerned about personal opinions and informal performance information rather than to use more sophisticated information (output and outcome measures). The institutional approach helps us to identify political responses to institutional pressures and understand the reasons for a reduced use in the Portuguese context.