application of distributed generation (dg) units in distribution networks has increased in recent years. sizing and sitting of dg units are two important factors which should be considered, especially for reduction of power losses in distribution system. this paper presents a new approach for dg placement in distribution systems using the mixed integer nonlinear programming (minlp). this approa...

In this work, thermo – elastic analysis for functionally graded thick – walled cylinder with temperature - dependent material properties at steady condition is carried out. The length of cylinder is infinite and loading is consist of internal hydrostatic pressure and temperature gradient. All of physical and mechanical properties expect the Poisson's ratio are considered as multiplied an expone...

Distributed generation (DG) has been widely used in distribution network to reduce the energy losses, improve voltage profile and system reliability, etc.  The location and capacity of DG units can influence on probability of protection mal-operation in distribution networks. In this paper, a novel model for DG planning is proposed to find the optimum DG location and sizing in radial distr...

This paper presents a new direct matrix inversion-less analysis for radial distribution systems (RDSs). The method can successfully deal with weakly meshed distribution systems. (WMDSs). Being easy to implement, direct methods (DMs) provide an excellent performance. Matrix inversion is the mean reason of divergence and low-efficiency in power flow algorithms. In this paper, the performance of t...

This study investigates the time-dependent long-term creep strain in a composite cylinder made of glass/vinylester with a unidirectional ply. The cylinder is subjected to an internal pressure and the boundary condition is free–free and acts as thermal insulation. The classical lamination theory (CLT) is used to derive the governing equations as a second-order equation to determine the radial, c...

In this paper, exact closed-form solutions for displacement and stress components of thick-walled functionally graded (FG) spherical pressure vessels are presented. To this aim, linear variation of properties, as an important case of the known power-law function model is used to describe the FG material distribution in thickness direction. Unlike the pervious studies, the vessels can have arbit...

In this paper, the problem of calculating the stress intensity factor (SIF) for an orthotropic thick-walled cylinder with a small radial crack subject to internal pressure is considered. The crack is assumed to be an edge crack on the external radius of the cylinder. The stress intensity factor is calculated by superposition of an uncracked cylinder with uniform stress distribution and a cylind...