Energy harvesting from earthquake for vibration-powered wireless sensors

Wireless sensor networks can facilitate the acquisition of useful data for the assessment and retrofitting of existing structures and infrastructures. In this perspective, recent studies have presented numerical and experimental results about self-powered wireless nodes for structural monitoring applications in the event of earthquake, wherein the energy is scavenged from seismic accelerations. A general computational approach for the analysis and design of energy harvesters under seismic loading, however, has not yet been presented. Therefore, this paper proposes a rational method that relies on the random vibrations theory for the electromechanical analysis of piezoelectric energy harvesters under seismic ground motion. In doing so, the ground acceleration is simulated by means of the Clough-Penzien filter. The considered piezoelectric harvester is a cantilever bimorph modeled as Euler-Bernoulli beam with concentrated mass at the free-end, and its global behavior is approximated by the dynamic response of the fundamental vibration mode only (which is tuned with the dominant frequency of the site soil). Once the Lyapunov equation of the coupled electromechanical problem has been formulated, mean and standard deviation of the generated electric energy are calculated. Numerical results for a cantilever bimorph which piezoelectric layers made of electrospun PVDF nanofibers are discussed in order to understand issues and perspectives about the use of wireless sensor nodes powered by earthquakes. A smart monitoring strategy for the experimental assessment of structures in areas struck by seismic events is finally illustrated

The Relationship Between the Civic Engagement of Parents and Children : a Cross-National Analysis of 18 European Countries

Although previous research has suggested the existence of a positive association between the political activities of parents and children, little is known about other forms of civic engagement. In particular, the literature lacks an international comparative study on the intergenerational transmission of civic involvement. Using Bayesian multilevel models on data from the European Union Statistics on Income and Living Conditions (EU-SILC) 2006 special module on social participation, this article tests hypotheses on the patterns of civic engagement of parents and children in 18 European countries with different political legacies. Our results show a positive association between the participation in associational activities of parents and children in all the considered countries, above and beyond individual and contextual characteristics. In particular, we do not find an evident East\u2013West gap in the socialization process, suggesting that the Communist past of Eastern and Central European countries has little influence on what can be considered a basic mechanism of civic learning

The Best Is Yet to Come? Attitudes towards gender roles among adolescents in 36 countries

In the present article, we look at attitudes toward gender roles among young women and men in 36 countries with different levels of societal gender inequality. By applying multilevel models to data from the International Civic and Citizenship Education Study 2009, the study contributes to our understanding of gender inequality by showing that (a) both young women and young men (in 8th grade; Mage = 14.39 years) display more gender-egalitarian attitudes in countries with higher levels of societal gender equality; (b) young women in all countries have more egalitarian attitudes toward gender roles than young men do, but (c) the gender gap in attitudes is more evident in more egalitarian contexts; and (d) a higher level of maternal education is associated with more gender-egalitarian attitudes among young women. In contrast, no statistically significant association emerges between maternal employment and young men\u2019s attitudes. Overall, the findings suggest that adolescents in different contexts are influenced by the dominant societal discourse on gender inequality, which they interiorize and display through their own attitudes toward gender roles. However, the findings also indicate that young women are more responsive to external cues than young men are. This result, coupled with the fact that young men in egalitarian contexts have not adopted gender-egalitarian attitudes to the same extent as young women, is concerning because it suggests a slowdown in the achievement of societal gender equality that is still far from being reache