In the current study, the surface composite sheet of AA2024/al203 has been fabricated using friction stir processing technique. The processing parameters during fabrication process; such as rotation speed, travel speed and number of passes have been investigated. The number of passes has a significant effect on the mechanical properties through tensile test. The results revealed that tensile strength improved with increasing passes number.Copy Right, IJAR, 2016,. All rights reserved. …………………………………………………………………………………………………….... Introduction:-Increasing demand for improving the properties of surfaces in order to meet with design and functional requirements. Friction stir processing (FSP) is one of the techniques for fabricating surface composites and modifying microstructural features, furthermore the improvement of mechanical properties. Process parameters are the key art of Friction Stir Processing. The stirring conditions (rotational and translational speeds) are important issues in FSP to obtain the desired mechanical properties.Many researchers were discussed the relation between the process parameters and the quality of welded or processed metals according to [ 1,2,3,4 ]. The Tensile strength is found to be increased with increasing the rotational speed up to specified limit for AA6351 Al alloys as reported by [ 5 ].The tensile properties and fracture locations have been investigated by many authors [ 6,7,8 ] they are fabricated metal sheets alloy using FSP. The results are revealed that the rotational speed has a significant influence on the tensile strength as a result of improving grain refinement of the material. The mechanisms of particle refinement during FSP of pure Al, and the effect of various processing parameters on the particle refinement have been studied by [ 9 ]. The investigators reported, that amount of heat generation during FSP was increased when rotational speed increase and decrease when transverse speed increase. Fabricating AA1050/SiC surface composite using FSP technique has been investigated by [ 10 ] the author concluded that , the formation of defects are causing at higher tool rotational speeds. The surface composite sheets are investigated by [ 11,12,13,14,15,16 ], they are concluded that tool rotation speed has a major effect on the mechanical properties and microstructure refinement.The effect of multi-pass FSP on the, microstructure, micro hardness and tensile strength on the metal alloy and composites have been studied by [ 17,18,19,20,21,22 ].Multi pass FSP not only improve the mechanical properties , but also get defect-free weld through adjusting the Welding parameters, including tool rotation rate, traverse speed, spindle tilt angle, and target depth [ 23 ] . multi-pass with even step (2, 4 up to 8-pass) FSP with 100% overlap was performed by [ 24 ] The results reported that multi-pass FSP were improved tensile properties of composites including UTS, yield strength (YS) and elongation. The authors were reasoned this improvement because of reduced
It is well documented that sport participation is relatively low among adolescent girls due to various constraints. Though much knowledge exists on these constraints, there is a need to examine if and whether constraints interact to influence sport participation.The purpose of this study was to develop a survey instrument to facilitate the examination of interactions of constraints to sport participation among adolescent girls, and to verify the survey's validity. Two theoretical frameworks were combined to guide the survey development. Newell's model of constraints was used to categorize constraints, into environmental, individual and task constraints.The 40 Developmental Assets Profile was used to index the constraints into broader categories within each constraint type. In total, 51 constraints were sorted into the combined frameworks which developed an 81-question survey. An expert panel was consulted to review for construct and content validity. This study has contributed a new survey instrument to the literature on constraints to sport participation. When used in different locations globally, the survey has the potential to reveal the most salient constraints, as well as build capacity for research to better inform future interventions and promote further discussions regarding sport.
In the present investigation, the tribological performance of epoxy-based nanocomposites filled with multiwall carbon nano-tubes (MWCNTs) and aluminum oxide (Al 2 O 3 ) nanoparticles in different weight percentages was investigated. The coefficient of friction (COF) and wear rate of the Epoxy/MWCNTs and Epoxy/Al 2 O 3 nanocomposites were evaluated using a pin-on-ring apparatus in a dry sliding conditions under different contact pressures and sliding speeds. The results demonstrated that the hardness, COF and wear rate were significantly improved by the dispersion of MWCNTs and Al 2 O 3 nanoparticles into the epoxy resin. Increasing the MWCNTs and Al 2 O 3 nanoparticles weight percent increases the hardness and reduces the COF and wear rate of the nanocomposites. The epoxy/MWCNTs nanocomposites showed lower COF, but higher wear rate when compared with epoxy/Al 2 O 3 nanocomposites.
The main purpose of this study is to investigate the functional significance of transitivity patterns in the American author, Hemingway's The Old Man and the Sea, depending mainly upon systemic-functional grammar originated by Michael Halliday. Transitivity is a set of grammatical choices made by language users to express their experiences (goings-on). These goings-on are realized by the verb type in the clause. The study aims at investigating the process types: material, mental, relational, behavioral, and existential, with a particular focus on the presentation of the protagonist's inner thoughts and his conscious practices. To achieve the aim of the study, the following objectives have been set: To examine the percentage of the frequent pattern of five process types in the novel, To investigate how the role of transitivity model is interpreted in the main character's actions and the complex mental states of the persona. Having conducted the transitivity analysis, data are analyzed qualitatively with using the proportion method to make up the percentage of each process type. The findings reveal that the material process is the most dominant. Second to this is the relational process. The mental process type is also significant, whereas behavioral and existential process types represent a slight portion of the texture of the novel. The dominance of material processes can justify the critics' arguments on the novel's dynamism and the old man's heroism represented in his struggle with the giant marlin. So, the study can be an attempt to explore how the theme of the novel is expressed by the author's linguistic choices.
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