We present a simple model for the friction of two solid bodies moving against each other. In a self consistent way we can obtain the dependence of the macroscopic friction force as a function of the driving velocity, the normal force and the ruggedness of the surfaces in contact. Our results are discussed in the context of friction laws used in earthquake models. PACS numbers: 46.30.Pa 81.40.Pa...

The accuracy performance of fringe projection profilometry (FPP) depends on accurate phase-to-height (PTH) mapping and system calibration. The existing PTH mapping is derived based on the condition that the plane formed by axes of camera and projector is perpendicular to the reference plane, and measurement error occurs when the condition is not met. In this paper, a new geometric model for FPP...

A signal machine is an abstract geometrical model for computation, proposed as an extension to the one-dimensional cellular automata, in which discrete time and space of cellular automata is replaced with continuous time and space in signal machine. A signal machine is defined as a set of meta-signals and a set of rules. A signal machine starts from an initial configuration which is a set of mo...

Physics-based simulation of systems such as virtual humans has benefited from recent advances in muscle actuation. However, to be manageable for motion controllers, muscles are usually solely represented by their action line, a polyline that does not include data on the tridimensional geometry of the muscle. This paper focuses on combining, by a controllable enhancement process, a functional an...

in this paper the reflection coefficient of electromagnetic wave incidence on the walls of the buildings and obstacles that occurs in mobile communication path was modified by solving the riccati nonlinear equations. for this purpose, the building walls are assumed inhomogeneous layers where their permittivity changes as function of the wall thickness. using this reflection coefficient, a new p...

we describe a variational problem on a surface under a constraintof geometrical character. necessary and sufficient conditions for the existence ofbifurcation points are provided. in local coordinates the problem corresponds toa quasilinear elliptic boundary value problem. the problem can be consideredas a physical model for several applications referring to continuum medium andmembranes.

With the growth in interest in geometrical ideas it is important to be clear about the nature of geometrical reasoning and how it develops. This paper provides an overview of three theoretical frameworks for the learning of geometrical reasoning: the van Hiele model of thinking in geometry, Fischbein’s theory of figural concepts, and Duval’s cognitive model of geometrical reasoning. Each of the...

In this paper, the causes of the crack initiation in cast iron bullion moulds in Meybod Steel Corporation are investigated and then some new geometrical models are presented to replace the current moulds. Finally, among the new presented models and according to the life assessment, the best model is selected and suggested as the replaced one. For this purpose, the three recommended moulds were ...