Many wearing processes are a result of the oblique impacts. Knowing the effective impact parameters on the wear mechanism would be helpful to have the more reliable designs. The H-DD (Hertz-Di Maio Di Renzo) nonlinear model of impact followed by the time increment procedure is used to simulate the impact process of a ball on a flat plate. Restitution parameters are extracted and compared with t...

To facilitate the manufacturing of a ball-end mill, this paper presents an algorithm for ball-end mills gashing by using a five-axis computer numerical control (CNC) grinding machine. In this study, the normal helix models are proposed. Then, based on the cutting edge geometric model and the machining mode of the five-axis computer numerical control (CNC) grinding machine, the coordinate of the...

qasim‘ali qayinis manaz?ir wa maraya, that has written in 11th century a.h./18th a.d., is one of the last works in muslim’s tradition of optical writings. in this work, qayini? has defined the scope of ‘ilm-i- manaz?ir and has referred some predecessor like euclid and kindi. moreover he proceeds popular topics in optical works like reflection and refraction of light, burning tools, rainbow, the...

It is well known that a three dimensional (closed, connected and compact) manifold is obtained by identifying boundary faces from a stellar ball a ⋆ S. The study of S/ ∼, two dimensional stellar sphere S with 2-simplexes identified in pairs leads us to the following conclusion: either a three dimensional manifold is homeomorphic to a sphere or to a stellar ball a⋆S with its boundary 2-simplexes...

In this paper, we propose a method for locating 3D position of a soccer ball from monocular image sequence of soccer games. Toward this goal, we adopted ground-model-to-image transformation together with physics-based approach that a ball follows the parabolic trajectory in the air. By using the transformation the heights of a ball can be easily calculated using simple triangular geometric rela...