Numerical solution of a piezoelectric contact problem

We consider a mathematical model, which describes a contact problem between a piezoelectric body and a conductive foundation. The linear electro-elastic constitutive law is employed to model the piezoelectric material. The process is static, the contact is frictionless and described with the normal compliance condition and an electric contact condition. Our aim is to present a detailed description of the numerical modelling of the problem. To this end, we introduce a discrete scheme, based on the finite element method to approximate the spatial variable. Then we treat the contact conditions by using a penalized approach and a version of Newton's method.  Finally, we provide numerical simulations in the study of a two-dimensional example and compare the regularized problem with the original one

Social Media Usage and User’s Self-Esteem: The Influence of Instagram’s posts on Millennials

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Marketing IntelligenceIn our digital era, social media has been playing a key role in connecting everyone from all over the world. This phenomenon raised its prevalence given the current pandemic situation, where lockdowns became part of our daily lives, and the internet has been the only escape route. While no one can deny the numerous benefits of such platforms, a less documented dark side of this technology and its effect on the average user’s behavior does exist. This research aims to investigate how social comparison is affecting social media’s consumers’ mental health. More specifically, how Instagram’s posts are affecting the Millennials’ view of their own lives, as well as how being exposed to other people’s lifestyles affect their self-esteem. In extreme cases, high degrees of social comparison might even lead to depression or suicide. To successfully address that, a quantitative and qualitative survey with multiple sections ranging from social media usage to self-esteem evaluation will be conducted, with young Millennials aged between 23 and 38 years old as the main recipient. Results show that an increase usage of Instagram leads to negative views of body image, as well as yielding a high recurrence of upward social comparison, which then have strictly negative effects on life satisfaction, and ultimately selfesteem

Numerical solution of a viscoelastic contact problem with normal compliance and unilateral constraint

A numerical method is presented for a mathematical model which describes the frictional contact between a viscoelastic body and an obstacle. The process is quasistatic and the material’s behavior is described by means of a viscoelastic constitutive law with long memory. The contact is modelled with normal compliance condition restricted by unilateral constraint, and associated to a version of Coulomb's law of dry friction. A solution algorithm is discussed and implemented. Finally, numerical simulation results are reported on a two-dimensional test problem. These simulations show the efficiency of the algorithm and the corresponding mechanical interpretations

Numerical solution of a viscoelastic contact problem with normal compliance and unilateral constraint

A numerical method is presented for a mathematical model which describes the frictional contact between a viscoelastic body and an obstacle. The process is quasistatic and the material’s behavior is described by means of a viscoelastic constitutive law with long memory. The contact is modelled with normal compliance condition restricted by unilateral constraint, and associated to a version of Coulomb's law of dry friction. A solution algorithm is discussed and implemented. Finally, numerical simulation results are reported on a two-dimensional test problem. These simulations show the efficiency of the algorithm and the corresponding mechanical interpretations

Numerical solution of a piezoelectric contact problem

We consider a mathematical model, which describes a contact problem between a piezoelectric body and a conductive foundation. The linear electro-elastic constitutive law is employed to model the piezoelectric material. The process is static, the contact is frictionless and described with the normal compliance condition and an electric contact condition. Our aim is to present a detailed description of the numerical modelling of the problem. To this end, we introduce a discrete scheme, based on the finite element method to approximate the spatial variable. Then we treat the contact conditions by using a penalized approach and a version of Newton's method.  Finally, we provide numerical simulations in the study of a two-dimensional example and compare the regularized problem with the original one

Long-term regional changes in inter-annual precipitation variability in the Campania Region, Southern Italy

Precipitation variability in space and time has been a focus of research over the past decades. The largest body of literature was essentially focused on long-term changes in average climates and in climate extremes. Analyses of the changes in the inter-annual climate variability (the year-to-year variability), which represent an index of climatic risk, received instead very less attention, but it represents an important issue in order to quantitatively measure the socioeconomic impact of climate change impact over water resources. In order to depict a general characterization of the long-term climate variability for the Campania region, located in Southern Italy within the Mediterranean basin, an analysis of the precipitation coefficient of variation, assumed as an index of inter-annual climate variability, was performed over the period 1918-2015 and compared with the annual precipitation regime and the intra-annual precipitation variability of the same region. The Mann-Kendall and the modified Mann-Kendall tests were applied to detect the sign and significance of the temporal changes and Sen's test was applied to quantify the temporal changes in inter-annual variability. The results illustrated a generalized condition (73% of total stations) of statistically significant increase of inter-annual variability distributed almost over the whole analyzed area, even though the detected change appeared rather moderate in magnitude. The relationship between annual precipitation, intra-annual precipitation variability, and inter-annual precipitation variability was not clearly identified for the studied region, likely because of the characteristics of climatic homogeneity for the area under investigation. However, the comparative analyzes clearly showed how, if the variations in the annual precipitation regime and in the intra-annual precipitation variability are poorly significant (respectively for 9% and 11% of total station), changes in inter-annual precipitation variability are strongly marked over the studied region

Spatio-temporal characterization And prediction of drought in Southern italy, case study: campania Region

2020 - 2021Drought is a natural phenomenon that has widespread and significant effects on the global economy, environment, industries, and communities. early drought detection allows for the implementation, mitigation strategies and measures before its occurrence. Therefore, drought assessment is critical in the planning and management of water resource systems, particularly during dry climatic periods. However, assessing droughts is not always simple. This study described and evaluated drought conditions in Campania (southern Italy) using an in-situ measurement database that spans a centennial period from 1918 to 2019. With the assistance of these tools, water managers may more accurately assess droughts and prepare in advance for water management operations during droughts. Since water resource management in our area was crucial, the Campania region in southern Italy was selected as the case study region. To achieve the objectives of this study, an analysis of the precipitation coefficient of variation, assumed as index of inter-annual climate variability, was first performed over the period 1918-2015. Based on the findings of the above analysis and with the aim of reconstructing continuous long-term monthly scale precipitation time series, the in-situ point measurements (observed at the rain gauge locations) for the two datasets were projected on a 10×10 km resolution grid covering the whole region by using a geostatistical interpolation approach. Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) time series were reconstructed for different accumulation timescales (from 3 to 48 months) to explore the full range of drought types. The modified Mann–Kendall and Sen's tests were applied to identify SPI and SPEI changes over time. In addition, the impact of the vegetation stress to better understand causes of the drought phenomenon was evaluated. Drought characteristics (Duration, severity and peak) were furthermore investigated for both moderate (SPI/SPEI ≤ −1) and extremely severe conditions (SPI/SPEI ≤ −2). Spatial autocorrelation was used too, to evaluate whether the different events studied have similar characteristics in terms of spatial aggregation, i.e., if there are areas increasingly affected by drought and how they are affected. The same events in which drought was already assessed with the SPI and SPEI indices were taken into consideration, i.e., the events of 1962, 1989, 2003 and 2017. [edited by Author]XXXIV cicl

Redefining Beauty: A quantitative investigation of the power of body-positive messaging on social media

Masteroppgave(MSc) in Master of Science in Strategic Marketing Management - Handelshøyskolen BI, 2024The portrayal of body image significantly influences user perceptions and interactions. This master’s thesis investigates how body-positive versus aspirational messaging on social media impacts perceived esteem, focusing on the mediating roles of competence, authenticity, warmth, and hubristic pride, alongside the moderating effect of attractiveness. Our study addresses a critical gap in existing research by exploring the nuanced psychological mechanisms behind social media engagement and body image representation. To key studies examined (1) the main effects of body-positive messaging on perceived esteem through an experimental design using Independent Samples T-Test, in which participants were exposed to body-positive or aspirational social media posts. Hayes PROCESS Model 4 was utilized to investigate the mediating effects. Additionally, we (2) extended this investigation by incorporating the moderating role of attractiveness using ANCOVA and Hayes PROCESS Model 8 for moderated mediation analysis. We argue that body-positive messaging significantly enhances perceived esteem, essentially through the mediator of competence. Notably, even when attractiveness was accounted for as a moderator, competency was found to be the most consistent mediator across analyses. This implies that in social media setting, individuals place a high emphasis on perceived skill and ability, which affects overall esteem. Additionally, compared to very attractive individuals, averagely attractive individuals received a greater boost in perceived esteem from body-positive messaging. We revealed a background effect of posting frequency, suggesting that participants' personal social media usage affects their perceptions of the posts of others. We provide theoretical, practical and managerial implications on the basis of this research