results the results showed that the epoxy plates 6 and 2 mm thick had the highest and the lowest averages of shielding effectiveness at 4.48 db and 1.90 db, respectively. however, increasing the thickness was useful up to 4 mm. in addition, in a similar attenuation pattern, x-band frequency was divided into lower, middle, and upper sections. the lower section had the highest shielding effective...

The response of collisionless plasmas to an applied potential can differ from classic Debye shielding, and when the potential is rapidly applied ~‘‘instantaneous shielding’’!, the shielding can differ from when it is slowly applied ~‘‘adiabatic shielding’’!. Experiments demonstrate that when a test potential well is applied to a one-dimensional pure-electron plasma, instantaneous and adiabatic ...

................................................................................................................................... iv 1.0 Introduction ...................................................................................................................... 1 2.0 Basic Concepts in Radiation Protection and Shielding .................................................... 1 2.1 Shieldin...

background: monte carlo simulations play a vital role in the calculation of the necessary shielding both for neutrons and photons. advanced and simple shielding materials against neutron and gamma rays were compared by simulation using the mcnb4b monte carlo code. the simulations were carried out for the three common neutron sources, namely the 252cf, the 241am/be and the dd neutron generator w...

Uncontrolled exposure to X-band frequency leads to health damage. One of the principles of radiation protection is shielding. But, conventional shielding materials have disadvantages. Therefore, studies of novel materials, as an alternative to conventional shielding materials, are required to obtain new electromagnetic shielding material. Therefore, this study investigated the electromagnetic s...

Introduction: Unwanted exposure of ionizing radiation may result in carcinogenesis, cell mutations, and organ failure. High-atomic number elements such as lead, tungsten, bismuth have been traditionally used for radiation protection. Theoretical and practical studies have shown that a variety of shielding materials e.g. polymer composites (PCs) can be used for attenuation of th...

Introduction: Computed tomography is one of the most powerful tools for investigating thorax disease, because it shows progression of lung disease much clearer than chest radiography. Technical advances in CT scanners have led to some abilities for CT scanners such as coverage of larger volume, lower noise and ability for acquiring image in one respiratory phase. However, this will be accompani...

In the present work a three-dimensional model has been developed to study shielding gas flow and heat transfer in a laser welding process using computational fluid dynamics. This investigation was motivated by problems met while using an optical system to track the weld path. The aim of this study was to investigate if the shielding gas flow could disturb the observation area of the optical sys...