Saravanan Umakanthan

In this paper, a methodology to control the surface error on a Doppler antenna using the concept of a variable geometry truss structure is proposed. A genetic algorithm is used to find the optimal location and number of actuators with the objective to minimize the construction and runtime costs. The optimization also takes into account the limitations in actuation. A piezoceramic-based actuator is used to demonstrate the effectiveness of the methodology. A simple illustration of 2D trusses, which could form a part of a Doppler antenna structure, is used to show the efficacy of the method. An analysis of the effectiveness of such a design is presented. The influence of the variables in the problem is examined and observations made. This study concludes that the smart antenna concept is a viable, feasible and effective option in design.

Here we investigate whether the deformation observed in an experiment in which the porcine circumflex coronary artery is subjected to inflation at constant length included in the class, r-r (R), θ=Θ z= ΛZ. We find that this is not the case and discuss its implications in the study of the mechanics of this artery. Moreover, we identify and quantify the uncertainty in the value of the invariants of the left Cauchy - Green tensor inferred from the 2D motion of markers affixed to the surface of the test specimen, and suggest that 3D tracking of markers is needed due to inherent bending and twisting induced by pressurization in vitro. © Society for Experimental Mechanics 2006.

There are several problems wherein it would be convenient to have representations for the stress from a stressed configuration as reference. We assume that the body undergoes finite elastic deformations (i.e., non-dissipative processes) from a stressed reference configuration but it is possible that a dissipative (inelastic) process could be the cause for the origin of the stresses in the reference configuration. We restrict ourselves to determining the representation for the stress in a body, from a stressed reference configuration, whose symmetry group in the stress free configuration (that is accessible from the stressed reference configuration) coincides with the full orthogonal group. We also find restrictions on the constitutive relation so that we have a model that exhibits physically acceptable response characteristics. © 2008 Elsevier Ltd. All rights reserved.