High Order Discontinuous Galerkin Method

Standard continuous Galerkin-based finite element methods have poor stability properties when applied to transport-dominated flow problems, so excessive numerical stabilization is needed. In contrast, the Discontinuous Galerkin method is known to have good stability properties when applied to first order hyperbolic problems

Introduction to hyperbolic equations and fluid-structure interaction

In this semester project we deal with hyperbolic partial differential equations and Fluid-Structure Interactio

A posteriori error estimates for the Electric Field Integral Equation on polyhedra

We present a residual-based a posteriori error estimate for the Electric Field Integral Equation (EFIE) on a bounded polyhedron. The EFIE is a variational equation formulated in a negative order Sobolev space on the surface of the polyhedron. We express the estimate in terms of square-integrable and thus computable quantities and derive global lower and upper bounds (up to oscillation terms).Comment: Submitted to Mathematics of Computatio

Comparison of agility in 13–16-year-old volleyball and football players and non-athletes

The aim of the study was to find and compare the agility abilities and anthropometric characteristics of 13–16-year-old volleyball and football players and adolescents not engaged in sports. The following research questions were posed: to find the agility results and anthropometric characteristics of volleyball and football players and non-athletes and to compare the agility results and anthropometric characteristics between athletes and not non-athletes and between different sports in both boys and girls. In total, 63 subjects participated in the study – 45 of them practised sports and 18 did not. Among those who practised sports, there were 19 volleyball and 26 football players. The following agility tests were applied in the study: T-test, four corners test, 5-0-5 run test and Illinois test. For data analysis, the Microsoft Excel program was used. The subjects’ height, weight, fat percentage and fat amount were measured. The means, minimum and maximum values, standard deviations, and body mass indices were calculated. To find correlations within the groups, correlation analysis was used. To establish statistical significance between the groups, Student’s t-test was used. The results revealed that, among both boys and girls, athletes were statistically significantly faster than non-athletes; only in Illinois test, there was no statistically significant difference. In girls, there were statistically significant differences between athletes and non-athletes in weight, fat percentage, fat amount and body mass index. In boys, however, there were no statistically significant differences in the body build characteristics between athletes and non-athletes. Football players were better in agility tests compared to volleyball players. Football boys were statistically significantly taller and older, and, in most tests, they were also statistically significantly faster than volleyball boys. Volleyball girls were statistically significantly taller and weighed more, but, in all tests, football girls were statistically significantly faster than volleyball girls. In all groups, the fat-related indicators, like fat percentage, fat amount and body mass index, were in mutual correlation. According to the body mass index scale, 45 subjects were of normal weight, 6 were overweight, 1 was obese and 11 were underweight. The authors of the paper hold the view that, namely in this age group, the athletes of sports games should practice agility and be tested in it, as, according to literature, the development of agility slows down at the age of 16–17 years, and therefore, can be one of the obstacles for reaching the top in adult athletes

Basic anthropometric measurements and proficiency in the game of adolescent (up to 16-year-old) male volleyballers at Estonian championships in three different years

The article analyses young male volleyballers’ age, body build and performance at Estonian championships for up to 16-year-olds at three tournaments – Tartu 2005, Viljandi 2006 and Rakvere 2008. In all these years, the participants were the eight best teams of Estonia at the moment. A total of 197 boys were studied; 13 body measurements were taken. Proficiency in the game was assessed for both teams in parallel with two computers provided with the program Game.Thirty-one indicators of proficiency in the game were calculated at each tournament. When we compared the tournament of 2005 with the tournament of 2008, we found statistically significant differences in nine indicators. The quality of the games has improved and the teams have become more equally matched. The number of spikes and blocks has increased; the indices of proficiency for all technical elements were higher in 2008 than in 2005. It is interesting that serve has changed from an element of putting the ball into the game into a genuinely attacking element. The number of ace serves has increased statistically significantly; the proficiency index of serves has rose by 2008. Unfortunately, however, the height and weight of the players decreased by 2008. This is a cause for concern, as taller players are more successful in volleyball

An embedded corrector problem to approximate the homogenized coefficients of an elliptic equation

We consider a diffusion equation with highly oscillatory coefficients that admits a homogenized limit. As an alternative to standard corrector problems, we introduce here an embedded corrector problem, written as a diffusion equation in the whole space in which the diffusion matrix is uniform outside some ball of radius $R$. Using that problem, we next introduce three approximations of the homogenized coefficients. These approximations, which are variants of the standard approximations obtained using truncated (supercell) corrector problems, are shown to converge when $R \to \infty$. We also discuss efficient numerical methods to solve the embedded corrector problem

A Process Model of Risk Communication: The Case of Global Climate Change

The authors describe a survey of public media use as it relates to different stages of awareness and concern regarding risk issues