This paper develops a nonlinear transient three-dimensional heat transfer finite element model and a rate independent three-dimensional deformation model, developed for the CO2 laser welding simulations in Al-6061-T6 alloy. Simulations are performed using an indirect coupled thermal-structural method for the process of welding. Temperature-dependent thermal properties of Al-6061-T6, effect of latent heat of fusion, and the convective and radiative boundary conditions are included in the model. The heat input to the model is assumed to be a Gaussian heat source. The finite element code ANSYS12, along with a few FORTRAN subroutines, are employed to obtain the numerical results. The benefit of the proposed methodology is that it offers the capability of optimizing laser welding process, and also provides a reliable estimation of the developed temperatures, as well as the thermal stress (residual stress) and strain fields reducing the experimental effort.
Pre-breakdown phenomenon was investigated within the two, non-mixed dielectric liquids; transformation oil and cresol. Finite element technique was used to follow the initiation and growth of plasma channels (streamer discharge) within pin-plane configuration. That was done for different spacing between the pin-electrode and the liquid-liquid interface. Streamer growth model assumed that, the streamer initiation occurs at the region of the highest value of electric field. Our study shows that the streamer initiates at the tip of the pin and growths toward the other electrode. The study shows, too, that the streamer path controlled by the difference of permittivity of the two liquids and spacing distance of the liquid-liquid interface fro
... Show MoreThis paper aims at analyzing Terry Bisson’s short story Bears Discover Fire stylistically by following both Gerard Genette’s theory of narratology (1980) and Short and Leech (1981) strategy for analyzing fictional works. Also trying to examine to what extent these models are applicable in analyzing the selected story. Stylistic analysis procedures help the readers/researchers to identify specific linguistic features in order to support literary interpretation and appreciation of literary texts. Style in fiction concentrates not on what is written, but on how a text is written. Each writer has his own style and techniques which distinguish him from other writers
ZnS nanoparticles were prepared by a simple microwave irradiation method under mild condition. The starting materials for the synthesis of ZnS quantum dots were zinc acetate (R & M Chemical) as zinc source, thioacetamide as a sulfur source and ethylene glycol as a solvent. All chemicals were analytical grade products and used without further purification. The quantum dots of ZnS with cubic structure were characterized by X-ray powder diffraction (XRD), the morphology of the film is seen by scanning electron microscopy (SEM). The particle size is determined by field effect scanning electron microscopy (FESEM), UV-Visible absorption spectroscopy and XRD. UV-Visible absorption spectroscopy analysis shows that the absorption peak of the as-prep
... Show MoreThis study aimed to identify the degree of use computers in administrative functions (planning, organization, controlling, and evaluation) among school leaders and assistants in public education schools in Sharoorah governorate ، as well as to identify obstacles of use computers in administrative functions from the perspective of school leaders and assistants male and female in public schools during the academic year 1439-1440, the study sample (66) school leaders and assistants, males (58), a and females (44), , and to answer the questions of the study, the researchers developed a questionnaire consisting of (60) items, has been verified sincerity and persistence, and data analysis was used frequencies, percentages an
... Show MoreIn this paper, photometric analysis of two short period group of the eclipsing binaries (RS CVn); RT And and BH Vir is presented. New physical and geometric parameters were obtained by performing two computer modeling. The first model is software package PHOEBE based on the Wilson–Devinney method, and the second is Binary Maker 3 (BM3).Our results are in good agreement with those obtained using the same modeling.
The study was performed to analyze the oropharynx airway and examine the influence of age and gender on the oropharynx volume configuration using cone beam computed tomography.
This study examined the cone beam computed tomographic images of 51 patients 25 male and 26 females, group matched for age and gender. The oropharynx airway volume and area between the posterior nasal spine and top of the epiglottis were measured and compared.
Background: This study designed to shade light on the important role of CBCT in accurate localization of the impacted maxillary canines. Materials and method: Fifty two unilateral and bilateral impacted maxillary canines from 30 patients (24 females and 6 males) were evaluated by a volumetric 3D images obtained from cone beam CT. All samples attended to the specialist health center of dentistry in Al-Sadder City referred to CBCT by oral surgeons or orthodontists to detect the exact position of impacted upper canine in cases when there was no bulging buccally or palatally which aids to detect the exact position. Results: Mesio-palatal angulations had the highest rate (63.5%) followed by mesio-labial (19.2%), vertical (labial) (9.6%), disto-p
... Show MoreThe designer must find the optimum match between the object's technical and economic needs and the performance and production requirements of the various material options when choosing material for an engineering application. This study proposes an integrated (hybrid) strategy for selecting the optimal material for an engineering design depending on design requirements. The primary objective is to determine the best candidate material for the drone wings based on Ashby's performance indices and then rank the result using a grey relational technique with the entropy weight method. Aluminum alloys, titanium alloys, composites, and wood have been suggested as suitable materials for manufacturing drone wings. The requirement
... Show MoreIn this paper, the effect size measures was discussed, which are useful in many estimation processes for direct effect and its relation with indirect and total effects. In addition, an algorithm to calculate the suggested measure of effect size was suggested that represent the ratio of direct effect to the effect of the estimated parameter using the Regression equation of the dependent variable on the mediator variable without using the independent variable in the model. Where this an algorithm clear the possibility to use this regression equation in Mediation Analysis, where usually used the Mediator and independent variable together when the dependent variable regresses on them. Also this an algorithm to show how effect of the
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