this study is focused on investigating the parameters of laser percussion drilling process of nickel-base super alloy inconel 718 with thickness of 1 mm. fiber laser with the power of 500 watts was used as the laser source. laser pulse frequency, duty cycle, laser power, focal point position, were assumed as the laser drilling process variables. the hole geometry features, i.e. entrance hole di...

one of the most important challenges in the development of urban railways network is the effects of railway vibrations on human and adjacent structures. although various investigations into the sources of railway vibrations have been conducted, very few research works have been reported on the influences of track geometry parameters on the level of vibrations. this is addressed in this research...

Alfred Tarski’s influence on computer science was indirect but significant in a number of directions and was in certain respects fundamental. Here surveyed is Tarski’s work on the decision procedure for algebra and geometry, the method of elimination of quantifiers, the semantics of formal languages, model-theoretic preservation theorems, and algebraic logic; various connections of each with co...

The concept of convexity plays an important role in the classical geometry of normed spaces and it is frequently used in several branches of nonlinear analysis. In recent years some papers that contain generalizations of the concept of convexity with the help of the measures of noncompactness have appeared. The Tauberian operators were introduced by Kalton and Wilansky (1976) and they appear in...

We find the combinations of momentum and domain-wall charges corresponding to BPS states preserving 1/4, 1/2 or 3/4 of D=4 N=1 supersymmetry, and we show how the supersymmetry algebra implies their stability. These states form the boundary of the convex cone associated with the Jordan algebra of 4 × 4 real symmetric matrices, and we explore some implications of the associated geometry. For the ...

When computing an average of positive definite (PD) matrices, the preservation of additional matrix structure is desirable for interpretations in applications. An interesting and widely present structure is that of PD Toeplitz matrices, which we endow with a geometry originating in signal processing theory. As an averaging operation, we consider the barycenter, or minimizer of the sum of square...

In computer graphics, methods for mesh simplification are common. However, most of them focus on static meshes, only few works have been proposed for simplifying deforming surfaces. In this paper, we propose a new method for the multiresolution representation of time-varying meshes based on deformation area and feature preservation. Our method uses the famous QEM (quadric error metric) as our b...

A method for lossy compression of genus-0 surfaces is presented. Geometry, texture and other surface attributes are incorporated in a unified manner. The input surfaces are represented by surfels (surface elements), i.e., by a set of disks with attributes. Each surfel, with its attribute vector, is optimally mapped onto a sphere in the sense of geodesic distance preservation. The resulting sphe...