the methods which are used to analyze microstrip antennas, are divited into three categories: empirical methods, semi-empirical methods and full-wave analysis. empirical and semi-empirical methods are generally based on some fundamental simplifying assumptions about quality of surface current distribution and substrate thickness. thses simplificatioms cause low accuracy in field evaluation. ful...

Introduction: Lead is a toxic metal that is found in the earth's crust and has been used by humans since 7000 years ago due to its density, malleability, high resistance and low melting point. The wide use of this metal in the industry, in addition to the exposure of workers, has led to widespread environmental pollution and public health problems in many parts of the world. Due to the widespre...

building on previous studies on the effectiveness of different types of written corrective feedback, the present study aimed at investigating whether direct focused corrective feedback and direct unfocused corrective feedback produced any differential effects on the accurate use of english articles by efl learners across two different proficiency levels (low and high). in current study, the par...

Need to high performance and low sensitivity explosives, led to wide spread research throughout the world. for access to modern and safe explosive materials. For this purpose high energy-density materials (HEDM) are good candidate. In this paper, has been reviewed the recent developments in the field of High energy density materials (HEDMs) and investigated their criteria and requirements. Also...

Background and aims: Extremely low frequency magnetic field (ELF) is part of Spectrum of electromagnetic waves with range 30 to 300 Hz. The average magnetic field exposures in the workplace have been found to be higher in “electrical occupations” than in other occupations such as office work. The interaction between magnetic fields produced by power lines and substations with living organisms a...