ion The technique of abstraction is based on making useful generalisations. The purpose of the generalisations is to understand and articulate the rules that apply to a specific domain of knowledge and even to discover rules that are shared between domains. Many people find it very difficult to think in terms of abstractions and are much more comfortable thinking in terms of specific instances....

The instability modes of the infinitesimally thin self-gravitating disk, which is composed of rotating and non-rotating parts, are investigated. By solving the dispersion relation numerically under various physical situations, two growing modes are found. They are the modified Jeans mode of rotating component or non-rotating one and the Landau mode by wave-particle (non-rotating component) inte...

In this study, two-dimensional electro-mechanical analysis of a composite rotating shaft subjected to non-axisymmetric internal pressure and applied voltage is investigated where hollow piezoelectric shaft reinforced by boron nitride nanotubes (BNNTs). Composite structure is modeled based on piezoelectric fiber reinforced composite (PFRC) theory and a representative volume element has been cons...

In this paper, a semi-analytical solution for magneto-thermo-elastic problem in an axisymmetric functionally graded (FG) hollow rotating disk with constant thickness placed in uniform magnetic and thermal fields with heat convection from disk’s surfaces is presented. Solution for stresses and perturbation of magnetic field vector in a thin FG rotating disk is determined using infinitesimal theo...

Accidents involving rotating equipment in chemical, petrochemical, petroleum, and gas plants can result in damage to other process equipment and catalysts along with lost production. Conversely, process upsets, process instrumentation failure, or failures of other process equipment can result in damage to rotating equipment. An effective rotating equipment loss prevention program will be an int...

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...

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...

abstract porous materials are commonly found in nature and as industrial materials such as wood, carbon, foams, ceramics and bricks. in order to use them effectively, their mechanical properties must be understood in relation to their micro-structures. foam made from non-flammable metal will remain non-flammable and the foam is generally recyclable back to its base material. this research work ...