an active antenna for transmitter application in s frequency band is designed and analyzed using harmonic balance technique which is based on the nonlinear model of active devices. in this active antenna, the amplifier is integrated with the radiator which is a rectangular patch antenna. this patch antenna is analyzed employing full-wave momentum method. by applying nonlinear model of transisto...

In this paper a simple tool for seismic design of steel structures for a selected ductility level is presented. For this purpose, a consistent set of earthquakes is selected and sorted based on the maximum acceleration of ground surface. The selected records are applied as the base motion to a single-degree-of-freedom system with strain hardening and the maximum response acceleration is determi...

In this paper, homotopy perturbation and modified Lindstedt-Poincare methods are employed for nonlinear free vibrational analysis of simply supported and double-clamped beams subjected to axial loads. Mid-plane stretching effect has also been accounted in the model. Galerkin's decomposition technique is implemented to convert the dimensionless equation of the motion to nonlinear ordinary differ...

This paper investigates the applicabilty of an innovative bracing, called Articulated Quadrilateral (AQ) bracing system, which uses shape memory alloys (SMAs), for retroffiting low-rise to high-rise vulnerable SMFRs against strong ground motions. The paper investigates brace fundamental engineering characteristics, design of the system and also configuration of the brace (the proportion of SMA ...

A proper composition of stiffness and ductility parameters is required to obtain a resistant and economic structure. Accordingly, Chevron Knee Braced Frame (CKBF) seems appropriate due to its proper seismic performance. The advantage of this system comes to having the capability of rapid and cheap replacement of chevron knee elements after an earthquake occurs. In this research, response modifi...

and Applied Analysis 3 Here, S t denotes the corresponding semigroup on H, generated by problem 1.1 , and ·, · 2 is the inner product in L2 Ω . The following energy equation holds: E0 E t ∫ t 0 δ‖v τ ‖λdτ, 2.3 where E t ≡ E u t , v t ≡ 1 2 ‖v t ‖2 J u t , 2.4 J u ≡ 1 2 a u 1 2 ( γ 1 )c u − 1 r b u , 2.5 with a u ≡ ‖u‖B, b u ≡ μ‖u‖r , c u ≡ β‖∇u‖ γ 1 2 . 2.6 Here, E0 ≡ E u0, v0 is the initial en...