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Mathematical Modeling of Electromagnetic Interactions with Biological Systems
Published in Andrew A. Marino, Modern Bioelectricity, 2020
The wave amplitude decreases to about 40% of initial value after traversing the penetration depth (skin depth) which is: δ=2/ωgμo1/2. The penetration depth decreases with increasing frequency and conductivity. Values of o at various frequencies are presented by Johnson and Guy (δ) for tissues with high and low water content. Beyond about 10 GHz (1 GHz = 109 Hz) plane waves do not penetrate very deeply into tissue.
Addition of Carbon Nanofibers to Cement Pastes for Electromagnetic Interference Shielding in Construction Applications
Published in Antonella D’Alessandro, Annibale Luigi Materazzi, Filippo Ubertini, Nanotechnology in Cement-Based Construction, 2020
E. Zornoza, O. Galao, F. J. Baeza, P. Garcés
The penetration depth of the wave, or skin depth [1, 11], is defined as the distance needed to observe a decrease of the EM wave amplitude by a factor e (2.718), that is, the depth that the wave has to penetrate in the material to observe an amplitude equal to 1/e times its initial value. The intensity of the electrical field diminishes exponentially inside the conductor. On the other hand, skin depth decreases when frequency, magnetic permeability, or conductivity increase, as can be appreciated in Eq. 15.3: () δ=1π·f·μ·σ,
Experimental Radio and Microwave Dosimetry
Published in Charles Polk, Elliot Postow, CRC Handbook of Biological Effects of Electromagnetic Fields, 2019
Maria A. Studhly, Stanislaw S. Stuchly
The optical properties of the materia! on which temperature profile is being measured with a thermographic camera affect the measurement accuracy. These are the emittance, reflectance, transmittance, and penetration depth.81 The reflectance and emittance are interrelated, and for opaque objects their sum is = 1. The transmittance and penetration depth are similarly related. The penetration depth is defined as the depth in the medium from which 1/e of the radiation emitted by an elemental volume in the medium escapes to the surface. The penetration depth is of importance for materials with nonuniform temperature distribution "in depth". A nonuniformly heated transparent material which is hotter inside than near the surface appears wanner than a similarly heated opaque material. Tissue phantom materials developed for bioelectromagnetics studies were tested,81 and for thicknesses > 0.4 mm no differences within the noise of 0.2°C were found (it is interesting to note that the muscle equivalent material 0.4 mm thick was visually, but not thermally, translucent). On the other hand, the transmittance of 0.05-mm thick polyethylene is 0.9, but its effect on determining the temperature distribution of the material underneath is negligible.8l
Recent developments in the application of microwave energy in process metallurgy at KUST
Published in Mineral Processing and Extractive Metallurgy Review, 2018
Ju Shaohua, Pritam Singh, Peng Jinhui, Aleksandar N. Nikoloski, Liu Chao, Guo Shenghui, R.P. Das, Zhang Libo
Microwaves interact with a material as they pass through it, losing energy to the material through a range of processes. The characteristics of this energy loss are dependent on the complex permittivity of the material, which is typically dependent on material temperature, and microwave wavelength. When designing microwave applications, it is necessary to take into account the penetration depth () of the microwaves into the material. The incident microwave can penetrate this distance into the material before its electric field intensity is diminished to 37% of its value at the surface. It determines what volume of the material gains energy from the microwaves. The penetration depth is inversely proportional to the frequency (Mingos and Baghurst 1991, 1999), and is a function of the properties of the material.
Measurement and modelling of organic matter’s altering effect on dielectric behavior of soil in the region of 200 MHz to 14 GHz
Published in Journal of Microwave Power and Electromagnetic Energy, 2023
Prachi Palta, Prabhdeep Kaur, K. S. Mann
In the field of remote sensing and agriculture, accurate and reliable determination of penetration depth holds great importance. Penetration depth is the measure of depth inside the material at which the power density of electromagnetic signal falls to 36.8% of its original value (at the surface) when EM waves fall normally on the surface of the material (Von Hippel 1954). It is given by the formula; where c is the speed of light, and are dielectric constant and dielectric loss factor, respectively, and is the frequency of incident EM signal.
Comparative energy-exergy and economic-environmental analyses of recently advanced solar photovoltaic and photovoltaic thermal hybrid dryers: a review
Published in Drying Technology, 2023
Saeid Mirzaei, Mehran Ameri, Hamid Mortezapour
The use of infrared radiation in the drying process is becoming more common today. Infrared drying has a more significant heat transfer coefficient, a shorter heating time, reduced energy usage, and more precise process control than the convection method.[97] Many researchers have emphasized the method’s convenience, variety of works, ease of installation on diverse equipment, and low setup cost compared to other approaches. The distance or depth at which the intensity of electromagnetic radiation reaches 37% of its original amount hitting the material’s surface is defined by a concept called penetration depth. The penetration depth is determined by the material’s composition and the impact radiation’s wavelength.[98] The infrared radiation drying method is ideal for materials with low thickness and high surfaces.[99] Drying by infrared radiation is used in conjunction with other procedures to improve the drying quality and reduce the drying time of the product. Infrared radiation can be combined in various ways, including hot air, microwave radiation, and vacuum. In recent years, solar energy has been employed to generate electrical power and aid the drying process due to the high consumption of electrical energy required to produce infrared radiation. Ziafouroghi and Abolfazli Esfahani[100] constructed an infrared solar dryer equipped with a photovoltaic panel and worked with the natural flow in 50, 60, and 70 (°C) material center temperature modes (Figure 17). Compared to the solar dryer, drying time was reduced by 75–83%, and drying time was reduced by 25–52% compared to the infrared dryer.