The current study performs an explicit nonlinear finite element simulation to predict temperature distribution and consequent stresses during the friction stir welding (FSW) of AA 7075-T651 alloy. The ABAQUS® finite element software was used to model and analyze the process steps that involve plunging, dwelling, and traverse stages. Techniques such as Arbitrary Lagrangian–Eulerian (ALE) formulation, adaptive meshing, and computational feature of mass scaling were utilized to simulate sequence events during the friction stir welding process. The contact between the welding tool and workpiece was modelled through applying Coulomb’s friction model with a nonlinear friction coefficient value. Also, the model considered the effect of nonlinear material properties as well as heat transfer conditions such as heat losses due to convection and thermal contact conductance between the workpiece and the backing plate interface on the thermal history. To validate the computational model results, an experimental procedure was carried out to measure temperature history on both sides of the specimen as well as the plunging force throughout the whole process time. The results obtained showed that symmetrical temperature distribution throughout the workpiece width was distinguished, implying that the tool rotation has a minor effect on the final temperature distribution. In addition, asymptotic V shape with high gradient temperature value in the weld nugget region after the full plunging was distinguished. Mechanical stresses and related plastic deformations generated, while achieving the FSW samples were evaluated in addition to the tool reaction force and heat generated to protect against tool failure.
In the hybrid coolingsolar systems , a solar collectoris used to convertsolar energy intoheat sourcein order to super heat therefrigerant leave thecompressor,andthisprocess helpsin the transformation ofrefrigerant state from gaseous statetothe liquid statein upper two-thirdsof thecondenserinstead of the lower two-thirdssuchas in thetraditional air-conditioning systems and this willreduce theenergyneeded torun the process ofcooling.In this research two hybrid air-conditioning system with an evacuated tube solar collector were used, therefrigerant was R22 and the capacity was 2 tons each.The tilt angle of the evacuated tube solar collector was changed and the solar collector fluid was replaced into oil instead of water.A comparison wasi
... Show MoreIn this research, the X-ray diffraction pattern was used, which was obtained experimentally after preparation of barium oxide powder. A program was used to analyze the X-ray diffraction lines of barium oxide nanoparticles, and then the particle size was calculated by using the Williamson-Hall method, where it was found that the value of the particle size is 25.356 nm. Also, the dislocation density was calculated, which is equal to1.555 x1015 (lines/nm2), and the value of the unit cell number was also calculated, as it is equal to 23831.
Dysregulation of matrix metalloproteinases-9 (MMP-9) and tissue inhibitors of
matrix metalloproteinases-1 (TIMP-1) may contribute to the development of
cardiovascular diseases in type 2 diabetes mellitus (T2DM) patients. The aim of this
study was to determine the effects of chronic hyperglycemia on serum
concentrations of MMP-9 and TIMP-1of T2DM patients without dyslipidemia (one
of atherosclerosis risk factors) and with duration less than 5 years in comparison
with T2DM patients with dyslipidemia and with duration more than 10 years and
controls. Also to investigate if serum levels of MMP-9 and TIMP-1 could be
potential markers for early detection of the development of cardiovascular
complications in T2DM pati
Through this descriptive study of the image of the Islamic Republic of Iran in the independent Iraqi press, the researcher relies on surveys, content analysis, and observation tools. The research community selected was the Iraqi independent press, represented by the Al-Zaman, Al-Dustour, and Al-Mada newspapers. The researcher adopts the comprehensive inventory method for newspaper issues produced between October 2019 and January 2020.
The results of this study show that Iran's interference in Iraq's internal affairs was one of the most prominent components of the picture that independent Iraqi newspapers seek to paint about the Islamic Republic of Iran.
Background: Multiple sclerosis is a chronic autoimmune inflammatory demyelinating disease of the central nervous system of unknown etiology. Different techniques and magnetic resonance image sequences are widely used and compared to each other to improve the detection of multiple sclerosis lesions in the spinal cord. Objective: To evaluate the ability of MRI short tau inversion recovery sequences in improvementof multiple sclerosis spinal cord lesion detection when compared to T2 weighted image sequences. Type of the study: A retrospective study. Methods: this study conducted from 15thAugust 2013 to 30thJune 2014 at Baghdad teaching hospital. 22 clinically definite MS patients with clinical features suggestive of spinal cord involvement,
... Show MoreThis research aimed to examine the correlation and influence of leader-member exchange in the organizational citizenship behavior in the existence of organizational trust as mediator variable among workers in ministry of migration and displaced, has been collecting data and information relating to research by designing questionnaire was distributed to the stratified random sample included (56) member of the workers in the ministry mentioned, and through the use of several statistical method were the main findings of research was the existence of a correlation relationship and influence between leader- member exchange and organizational trust, while the results confirmed no correlation and influen
... Show MoreThe organizations, represented by its Management, are working hard in various ways to identify the environmental disturbances that occur in their environment and to investigate and follow up the movement of these disturbances and to respond to them through the decisions they make in an attempt to keep pace with the work and sustainability of their activities, including those decisions, marketing decisions taken by the environmental disturbulence in the market of the organization, the inability of these organizations to read the indicators of these disturbulence correctly displays their marketing effectiveness to vibration and decline in the negative.The current research is based on a fundamental problem that envi
... Show MoreThe research aims to show the dimensions of organizational trust represented by (administrative policies opportunities for innovation and self innovation and self- realization,availability of information,prevailing organizational values) and its reiationship to achieving the strategic position of banks represented by formation of expectations,buiiding networks,learning operations As the research was applied in each of the banks (middle east)Iraqi investment,Al-Ahly Iraqi, Business Bay, Al- Mansour investment bank),the qusestionnaire was adopted as a tool to collect data and information from the sample number (138)who are in the site (department director, division ,M.division director ,division officer, unit officer)the statistica
... Show MoreStrategy Descrtibes How an Organization Matches its own Capabilites With Opportunities in Environment , in Order to Accomplish its Overall Objectives , So That The Organization is Considering Responding to Challenges by Adopting one or More of Strategies, Like Differentioning its Product, or Achieving Cost Leadership.
The Key Role of Management Accountant is to Evlaute The Successful it Has Been in Implementing Organization Strategy.
This Research Target to Explain The Key Role of Management Accountant in Evaluate of Organization Strategy. by Strategic Analysis of Operating Income From Specific Sources Such as Cost Savings and Growth in Stead of Emphasizing Only The Aggrega
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