elastic solutions applicable to single underground openings usually suffer from geometry related simplification. most tunnel shapes possess two axes of symmetry while a wide range of geometries used in tunneling practice involve only one symmetry axis. d-shape or horse-shoe shape tunnels and others with arched roof and floor are examples of the later category (one symmetry axis). in the present...

among various practical measures used for restriction of the ground surface settlement in such tunnels driven in soft ground, selection of an appropriate excavation method plays a significant role. in this paper, employing suggested diagram by yu & chern, corresponding values of niayesh tunnel has been inserted into the diagram. later, two excavation methods namely: central diaphragm and si...

In this paper, a new method for radar cross section reduction of a monopole antenna is proposed. In this method, a plasma helix like fluorescent bulbs is placed around the antenna element. The selected plasma parameter for this medium acts as an absorber without disturbing the antenna performance. The simulations show that radar cross section of simulated antenna is reduced in a wide frequency ...

This paper studies in an overlapping generations forest economy the conditions under which money and/or timber bequests occur across generations, assuming the usual case of one-sided altruism. We assume nonindustrial landowners have preferences for consumption and for amenities from unharvested forest stock. Within this framework, we examine conditions under which landowners choose to leave tim...

In this paper a method is presented for torsional analysis of non-homogeneous tubes with arbitrarily shaped cross-sections. A previously presented method based on Bredt’s theory is extended to achieve formulas for torsional analysis. Shear modulus varies through the thickness according to a power law distribution. To validate the accuracy of the presented formulas for angle of twist and shear s...