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In this paper, two-phase air–water flow was investigated experimentally and simulated numerically using VOF method. The tests are conducted in Multiphase Flow Lab. of Tarbiat Modares University. In order to evaluate the rib effect on flow regimes, experimental investigation was conducted with ribs of different width and pitch where assembled on front and back side walls (side walls) of the duct during different test runs. The rib width and pitch were held constant during each test. The experimental work considered for different regimes of wavy, plug and slug which generated in the ducts with and without rib applying various phase velocities. The effects of using ribs on regime boundaries are presented in the flow diagrams and discussed in details. Compared to the smooth duct, the ribbed duct affects the different regime boundary positions noticeabily. The results showed that in the duct with small sizes ribs, the first slug initiates at longer time and distance in compare to the duct equipped with bigger size ribs. The results show that for normal operational flow velocities, the ribbed duct decreases the slug area on flow diagram map in compare to smooth duct. However, ribs facilitate the slug regime initiation for phase velocities in accordance with slug generation, which is not benefit of operational condition.

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In this research, three dimensional grain burn-back of solid rocket motors is simulated based on level set method and its accuracy is increased according to marching cube algorithm (MCA). To that end and according to requirements of level set method, grain burn-back is simulated during three steps included grid generation, distance function determination, and calculation of burn-back parameters. In this article, with focus on last step, we will compare strengths and weaknesses of grain burn-back analysis for common methods such as captured cell, three dimensional cut cell, sectional, and Heaviside Delta Dirac and in following, we introduce and run MCA. In order to validation, firstly three simple grains such as cylindrical, quad and hexahedron are considered and the performance of capture cell, 3D cut cell and sectional methods are compared with MCA in terms of accuracy and CPU time. Then, to evaluate the new method facing complex and practical grains, burn-back results of conocyle and NAWC N.13 grains is compared with MCA and heaviside/dirac delta methods. The obtained results show that MCA has a better performance at CPU time and accuracy.

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“Tensegrity” refers to a class of discrete structures with two force members (bars and cables) wherein bars only take tensile loads and cables only take compressive loads. The pre stressed members are interconnected so as to form a self equilibrium structure. Compared to a truss supporting the same external loading, a tensegrity structure has fewer members and could weigh less. Determining the stable topology (member connectivities), form (node coordinates) and size (cross sectional areas of members) of a tensegrity structure for weight minimization is a challenging task, as the governing equations are nonlinear and the conventional matrix analysis methods cannot be used. This article addresses the weight minimization of a class one tensegrity structure with a given number of bars and cables, anchored at certain nodes and supporting given load(s) at certain node(s). Member connectivities and their cross sectional areas and force densities are taken as design variables, whereas the members’ strength and buckling requirements and maximum nodal displacements constitute the constraints, along with the coordinates of the floating nodes to make the structure symmetric. Constraints are evaluated through the nonlinear shape design of the self equilibrium structure and the linear analysis of the loaded structure, assuming small displacements. Using a novel approach, optimization is simultaneously performed in multiple promising areas of the solution space, resulting in multiple, optimum solutions. The diversity of the solutions is demonstrated by applying the proposed approach to a number of structural design problem.

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Turkeys, including white meat, have been ranked second in abundance. In this study, were increased the quality, tenderization and sensory properties of turkey fillet by marinade solution. The effect of the addition of marinade solutions (5levels: distilled water (control sample), marinade solution (water + 5% Lactic acid + 3% NaCl), marinade solution and 900 ppm Oliveria decumbens Vent Essential oil, solution and 1400 ppm Ferula assa- foetida Extract) and time (2levels: 24 and 48h) on the texture characteristics of turkey’s meat were investigated based on completely randomized design. The studied traits included tissue shear force, microscopic structure, color evaluation, sensory evaluation, pH, cooking loss and absorption percent. The effect of marinade solution was significant on pH, shear force, Sensory quality and the effect of time was significant on shear force (p<0.05). In addition, salt and acid, in addition to crunching and flavoring the meat, increased yield, reduced cooking time and improved texture. The specimens treated with marinade had a significant difference in the maximum shear force for cutting (p<0.05). L* (lightness) of meat increased after meringue (p<0.05). The simultaneous use of acid, sodium chloride and aromatic herbs was a better option to improve the flavor and odor of meat and to increase its marketability.