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Research subject:Well-designed plastic foams, with respect to their cell density and cell size, open-or-close cells, and the cell uniformity, compared to their counterpart unfoamed plastic parts, beside of having the advantages of less material consumption, dimensional stability, better processability, and a higher surface quality, they can have superior mechanical and physical properties, including strength to weight, impact strength, thermal and dielectric properties. The temperature distribution in the different zones of the extruder, the qualities and quantities of the nanoparticle additives and their dispersion in the polymer matrix can have significant effect on the mechanical properties of the produced foams by the extruder.
Research approach: In this study, using an extruder, MA-g-polypropylene microcellular foams, containing 3, 7 and 9 wt% of nano-clay particles, were produced under three temperature arrangements on the extruder and the material and the processing effects on the mechanical properties were investigated.  
Main results: The result of this investigation shows that adding of nanoclay improves the mechanical properties of MA-g-PP.s foams. As an example, the results show that the sample with 7 wt% of surface modified nanoclay, owns about 10% higher impact toughness compared to the samples produced without nanoclay. Also for the same samples a rise of about 5% was recorded in Young's modulus. The microstructural studies of the produced foams by scanning electron microscope (SEM) show that adding of nanoclay can result on more foam uniformity and smaller cell size. In this study, the smallest average cell size (87.5 μm) and the lowest density (0.3 g/cm³) were recorded for a sample with 7wt% nanoclay.

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In this paper, the problem of the navigation error effect for the optimal and constraint Trajectory of the UAVs that are required to fly at low altitude over terrains has been discussed. Due to the increasing deviation problem of inertial navigation systems in terms of time, having a safe flight and collision avoidance with terrain at low altitude is the main point in the trajectory design of this type of the vehicles. On the other hand, some of these vehicles use Terrain Contour Matching (TERCOM) as a navigation aiding system. This system is more efficient in rough terrains, and providing the requirements of this system beside other constraints is a complex task. In this paper is tried to meet these constraints in the trajectory design process. For this purpose, an algorithm based on the layered network flow on the digital terrain maps used in a manner that has a high potential in adoption of various constraints and optimal trajectory is generated. Then, using equations of motion on a terrain digital data in 3D space with the dynamical constraints and different optimality criteria, a complete model of navigation error and also parameters affecting TERCOM has been developed to generate feasible path reducing terrain collision probability to zero.. Numerical results show validity of this issue.