− div ( |∇up|p−2∇up ) = f in Ω up = 0 on ∂Ω, where p > 1 and Ω is a bounded open set of R (N ≥ 2) with Lipschitz boundary. We analyze the case where Ω is a ball and the datum f is a non-negative radially decreasing function belonging to the Lorentz space LN,∞(Ω) and the case where the datum f belongs to the dual space W−1,∞(Ω). We are interested in finding the pointwise limit of up as p goes to...

The size of sports fields considerably varies from a few meters for table tennis to hundreds of meters for golf. We first show that this size is mainly fixed by the range of the projectile, that is, by the aerodynamic properties of the ball (mass, surface, drag coefficient) and its maximal velocity in the game. This allows us to propose general classifications for sports played with a ball.

Graphical Abstract “When I was a kid wanted to be an adult. Be careful what you wish for! … The most important thing have learned from my students is that ideas are not necessarily the best ones …” Find out more about Liam Ball in his Introducing Profile.

A deeper understanding of the milling operation of ball mills helps mineral processing engineers to control and optimize them, and therefore, reduce their consuming power. In this work, the milling operation of ball mills is investigated using two methods, i.e. DEM and combined DEM-SPH. First, a pilot scale ball mill with no lifter is simulated by both methods. Then another pilot scale ball mil...

Ball valve is one of valves that have many applications in industry especially in gas delivery systems. This kind of valve is categorized in the on- off flow control valve. This study aims to investigate unusual application of ball valve to control fluid flow in the oil and gas industry and its destructive effect including erosion of ball and body of valve. Simulation of industrial ball valve i...

An instantaneous rigid force model for prediction of cutting forces in ball-end milling of  sculptured surfaces is presented in this paper. A commercially available geometric engine is used to represent the cutting edge, cutter and updated part geometries. The cutter used in this work is an insert type ball-end mill. Intersecting an inclined plane with the cutter ball nose generates the cutting...

The production of ordinary Portland cement (OPC) as the most expensive constituent of concrete is associated with destructive environmental effects and significant energy consumption. Thus, the use of supplementary cementitious materials such as Natural or synthetic pozzolans is a fundamental solution that affects the kinetics of hydration of cementitious materials. In this article, to evaluate...

Goalkeeper robot in the league of humanoid robots has a key role so that its wrong decision and incorrect jump can cause changes in the result of a competition. This paper presents a method to detect the ball on the ground during the match, determine the coordinates of the ball with respect to the robot, calculating the speed and direction of the ball and eventually the time and place that the ...