Sharif Digital Repository

The paper presents a computational model and the corresponding algorithm for estimating the arc energy distribution to conductive, convective and radiative heat transfer in an electric arc furnace (EAF). The proposed algorithm uses channel arc model (CAM) in order to compute the distribution of the arc energy through empirical equations (to approximate arc radius), ideal gas law (to approximate arc density) and results of magneto-hydro-dynamic (MHD) models (to approximate arc pressure, temperature and velocity). Results obtained using the proposed algorithm are comparable with other similar studies; however, in contrast to other arc-energy distribution models, this model requires only two... 

In this paper, an analysis of kinematics of the isotropic elastic Cosserat continuum is presented in infinitesimal and finite deformations. Emphasis is given on the applicability of corotational stress rates for hypoelasticity in micro-polar continua. A non-linear finite element analysis is performed with an explicit formulation of tangent stiffness matrices in the case of Truesdell stress and couple stress rates. A comprehensive path-dependent procedure is employed based on the arc-length method to calculate the stability points and handle the snap-back problem. Finally, the accuracy and efficiency of method are illustrated by numerical examples  

An adaptive extended Kalman filter is designed to estimate the arc length in a gas metal arc welding system. The simulation results show that the estimated variables track the true variables of the non-linear model with negligible error and are robust against parameters uncertainties. The proposed estimator also operates adequately in a highly noisy welding environment. Because of the low computational requirements and little lag produced in the process dynamic, use of the proposed estimator would be valuable in the design of a controller for the gas metal arc welding system  

Keratoconus (KC) is a progressive corneal disease. It is mostly characterized by corneal thinning and irregular steepening as well as formation of cone-shaped regions on the cornea. Amongst treatment modalities, implantation of Intrastromal Corneal Ring Segments (ICRSs) could decrease corneal surface irregularities. However, controversy exists over the selection of proper ICRSs. Here, the aim was to compare the effects of two sets of ICRSs. The ICRSs were identical both in cross-section and total arc length. The results showed that under normal physiological range of intraocular pressures (IOPs), the two selected ICRSs caused slightly different deformations in the same in-silico keratoconic... 

The effects of real and Gleeble simulated double pass thermal cycles on the properties of the intercritically reheated coarse grained heat affected zones in X80 microalloyed pipeline steel has been investigated. The Gleeble simulated process involved heating the X80 steel specimens to the first peak temperature of 1400°C and then reheating to the second peak temperature of 800°C, with different cooling rates. The size and area fraction of martensite/austenite (M/A) constituents were obtained by a combination of field emission scanning electron microscopes and image analysis software. In addition, misorientation was characterized by electron back-scatter diffraction analysis. It is clear that... 

The objective of this investigation was to provide a detailed evaluation of the heat affected zone properties of a high-strength pipeline steel. The X80 high-strength low-alloy microalloyed steel was supplied as a hot rolled plate with accelerated cooling. The four-wire tandem submerged arc welding process with different heat input was used to generate welded joints. The microstructure of the heat affected zone depended on heat input values. M/A constituent appeared in the microstructure of HAZ region for all of the specimens along the prior-austenite grain boundaries and between bainitic ferrite laths. Charpy impact specimens were notched in four locations: FL (fusion line), FL+1mm, FL+2mm... 

The influence of thermal cycles on the properties of the coarse grained heat affected zone in X80 microalloyed steel has been investigated. The thermal simulated involved heating the X80 steel specimens to the peak temperature of 1400 °C, with different cooling rates. The four-wire tandem submerged arc welding process, with different heat input values, was used to generate a welded microstructure. The martensite/austenite constituent appeared in the microstructure of the heat affected zone region for all the specimens along the prior-austenite grain boundaries and between the bainitic ferrite laths. The blocky-like and stringer martensite/austenite morphology were observed in the heat...