We propose that a significant fraction of the ultracompact H II regions found in massive star-forming clouds are the result of the interaction of the wind and ionizing radiation from a young massive star with the clumpy molecular cloud gas in its neighbourhood. Distributed mass loading in the flow allows the compact nebulae to be long-lived. In this paper, we discuss a particularly simple case,...

The need of polygonal elements to represent the domain is gaining interest among structural engineers. The objective is to perform static analysis and topology optimization of a given continuum domain using the rational fraction type shape functions of six node hexagonal elements. In this paper, the main focus is to perform the topology optimization of two-dimensional plate structures using Evo...

In this paper, nonlinear analytical solution of pressurized thick cylindrical shells with variable thickness made of hyperelastic materials is presented. The governing equilibrium equations for the cylindrical shell with variable thickness under non-uniform internal pressure are derived based on first-order shear deformation theory (FSDT). The shell is assumed to be made of isotropic and homoge...

Local motion detectors can only provide the velocity component perpendicular to a moving line that crosses their receptive field, leading to an ambiguity known as the "aperture problem". This problem is solved exactly for rigid objects translating in the screen plane via the intersection of constraints (IOC). In natural scenes, however, object motions are not restricted to fronto-parallel trans...

The large deflection phenomenon of an initially flat circular membrane under out-of-plane gas pressure loading is usually involved in many technical applications, such as the blister or bulge tests, where a uniform in-plane stress often present before deflection. However, there still lack effective closed-form solution for problem with initial stress. In this study, formulated and solved analyt...

In the current research the maximum deflection of circular plates made of AA5010 and AA1100 alloys under blast load was investigated. Shock waves were produced by exploding a spherical charge in different distances from the center of plates. The ABAQUS software uses conwep equation for blast loading analysis. It was found the results of these simulations have about 30% to 40% inaccuracy in comp...

This thesis focuses on the Fast Multipole Method which hierarchically solves the N-body problem with a linear operation count for any given precision. When considering Laplace equation, we aim at treating efficiently all particle distributions that arise in astrophysics and in molecular dynamics. We first study two different expressions of the main operator (“multipole-to-local”) as well as the...

The notion of theoretical strength, the critical stress at which a perfect crystal under uniform loading becomes structurally unstable, is extended to non-uniform loading. A position-dependent defect nucleation criterion has been derived and applied in molecular dynamics (MD) and finite-element simulations of dislocation emission in single-crystal nanoindentation. The resulting measure has the ...