Given a set S of n points in the plane, a quadrangulation of S is a planar subdivision whose vertices are the points of S, whose outer face is the convex hull of S, and every face of the subdivision (except possibly the outer face) is a quadrilateral. We show that S admits a quadrangulation if and only if S does not have an odd number of extreme points. If S admits a quadrangulation, we present...

We have developed a new numerical code to study the evolution of distorted, rotating black holes. We discuss the numerical methods and gauge conditions we developed to evolve such spacetimes. The code has been put through a series of tests, and we report on (a) results of comparisons with codes designed to evolve non-rotating holes, (b) evolution of Kerr spacetimes for which analytic properties...

Recently friction stir welding for manufacturing of welded tubes has been developed. Friction stir welding is a continuous solid state welding process in which a non-consumable rotating tool using severe plastic deformation Can join materials can be join materials. Commonly, a portion of a specially shaped rotating tool is plunged between metalsjoint cross section and adjacent faces of the join...

in recent years, the hydroforming due to reduction in weight and increase in strength of automotive parts has attracted attention of the automotive industry. thus, the knowledge of the process to produce parts with desired quality and accuracy has been growing. one of the effective methods in improving the formability in the hydroforming is known as pulsating hydroforming. however, the reason o...

in this paper, the deep drawing process of tailor welded blanks is simulated using the finite element modelling and verified using the experimental results available in the literature. then the effect of die and material properties on the welding line movement is investigated. it is seen that the most effective material parameters on weld line movement are different between sheet metal thicknes...

surge and rotating stall phenomena are two dynamic instabilities that occur in both axial and centrifugal compressors. surge is the stream instability phenomenon in compressor that imposes severe damages to the compressors. nowadays, suppressing surge phenomenon is one of the most important issues in oil and gas industries, especially when flow reduction or gas reflux is considered. this resear...

in industry, flow instabilities are important in journal bearings at high rotational speeds. for inviscid flows between two rotating coaxial cylinders, an instability criterion was introduced by taylor-couette. however, viscosity may play as stabilizer or destabilize in such flows. in this work, stability theories were reviewed for two coaxial rotating cylinders. then, flow instability patterns...

James White lehnte 1846 die Lehre von der Dreieinigkeit als „das alte unbiblische trinitarische Dogma“ ab. Ein Jahrhundert später stimmte die Gemeinde, die er neben anderen gegründet hatte, für eine offizielle Erklärung von „Glaubenspunkten“, die den Glauben an eine Dreieinigkeit einschloss. Das eine große theologische Veränderung stattfand, ist kein Diskussionspunkt mehr. Das die meisten der f...

Statement of the Problem: Understanding about impression materials, their properties, uses and manipulation can guide operators towards having more successful restorations. Purpose: The aim of this in vitro study was to compare the accuracy of a condensation silicone impression material, Optosil, and an addition poly siloxane impression material, Elite-HD. Materials and Method: A laboratory mod...