Showing 2 results for M. Bahrami
M. Bahrami and S. H. Sadati,
Volume 20, Issue 1 (7-2001)
Abstract
In this paper, some results are provided for minimum time roll about velocity vector maneuvering with thrust-vectoring and aerodynamic control in effect. The mathematical model for attitude motions of the aircraft is developed. First order necessary conditions for optimality using Pontryagen principle is applied, and the existence of an extreme family of solutions for the maneuver is shown. Multiple shooting method is used to obtain the numerical results. An estimate of maneuver time reduction resulting from thrust-vectoring is obtained.
Keywords: Multiple Shooting Method Minimum time Thrust-Vectoring Maneuverability Aerodynamics
M. Bahrami, M.h. Fathi, M. Ahmadian,
Volume 32, Issue 1 (Jun 2013)
Abstract
Short life of current total hip replacement metallic implants is generally dependent on the aseptic loosening of the implant, which occurs due to mismatch of elastic modulus between bone and metallic implant materials. Decreasing in elasticmodulus of implant could be successful. Forsterite is biocompatible and bioactive ceramic which has suitable mechanical properties. In presented research the composite materials based on Co-Cr-Mo alloy with 10, 15 and 20wt% of forsteritenanopowder as reinforcement were fabricated and mechanical behavior of the composites were evaluated. Composites were fabricated by ball milling, cold pressing and sintering. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for characterization and evaluation phase composition and microstructure of the composites. Density, microhardness, compressive strength and elastic modulus of fabricated composites were evaluated. Obtained results showed elastic modulus of composite materials based on Co-Cr-Mo alloy reinforced with 10, 15 and 20wt% of forsteritenanopowder decreased significantly. Results also showed that the compressive strength of Co-base alloy composites reinforced with 10, 15 and 20 wt% forsterite were lower than cast Co-Cr-Mo alloy. With increasing in the content of reinforcement, compressive strength of the composites were decreased. Microhardness of prepared composites were higher than cast Co-Cr-Mo alloy. With increasing in content of bioceramic reinforcement, microhardness of the composites were increased.
