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EM behavior when the wavelength is about the same size as the object
Published in James R. Nagel, Cynthia M. Furse, Douglas A. Christensen, Carl H. Durney, Basic Introduction to Bioelectromagnetics, 2018
James R. Nagel, Cynthia M. Furse, Douglas A. Christensen, Carl H. Durney
The skin depth in other good conductors is similarly very small at high frequencies. At lower frequencies, the skin depth is correspondingly greater, as given by Eq. (3.8). One of the important impacts of the skin effect is seen in coated conductors. If a copper wire is coated with tin in order to make it easier to solder, for instance, the currents can be contained in the tin rather than the copper at high frequencies due to the skin effect. Tin is much more lossy than copper, and therefore whatever system is created with this wire is not as efficient as it would have been with copper alone; the coated system requires more power and creates more heat than with copper alone. Skin depth is an important concept in medical devices. If the skin depth is low, an imaging system will see only the surface of the body. This is used in airport scanners, for instance, where the waves can propagate through (dry, nearly lossless) clothing to see the surface of the body and any metallic objects (such as weapons). Penetration into the body is minimal (skin depth is low), so this imaging is limited to the surface only.
Thermal Incineration
Published in Paul N. Cheremisinoff, Air Pollution Control and Design for Industry, 2018
We might properly apply the term afterburner to a fume or waste gas incinerator which is being used to destroy gases coming from a combustion operation where the combustion is not complete. For example, waste copper wire is often reclaimed by burning off insulation in some type of furnace or retort. It is usually impossible to get enough air through the bundle of waste copper wire to achieve complete combustion of the insulation. Therefore, the stack from this furnace will contain combustible materials which should not be released to the atmosphere. By placing an auxiliary burner in the stack to reheat the waste gases to a higher temperature, and by adding additional air or oxygen, an afterburning is achieved which gives acceptable products of combustion. What has been done, in this instance, is to take a poor combustion operation and give it a second chance by the addition of air to complete what really should have been done in the first place.
Network Technology and Methodology
Published in Fred Huffman, Practical IP and Telecom for Broadcast Engineering and Operations, 2013
Transmission is the act of propagating energy or moving information from point A to point B. In the context of communications networking, the term includes sending and receiving. If the heart of the network is the clocking system, transmission is analogous to the arteries and capillaries carrying oxygen from the lungs to the brain and other important organs. Modern communications network transmission seems to have started when someone figured out that a direct current voltage applied to one end of a pair of wires could be detected at the other end as long as the conductive characteristics of the path are intact. Without the underlying transmission facilities, today’s IP would be of no more value than Samuel B. Morse’s telegraph code without a baseband electrical signal transmission facility. Successful transmission requires a viable medium. Electrical transmission works well on copper wire. Radio transmission moves easily through free space, where electrical current doesn’t travel well. Light waves move through transparent glass, but opaque objects block them.
Induction assisted friction stir welding: a review
Published in Australian Journal of Mechanical Engineering, 2020
All metals show electric resistance while conducting electricity. The resistance to this flow of current causes losses in power that result in the formation of heat. Some metals, such as silver and copper, have very low resistance and, as a result they are very good conductors. Copper wires are used to carry electricity through power lines because of the low heat losses during transmission. Other metals, such as steel, have high resistance to an electric current, so that when an electric current is passed through steel, substantial heat is produced (Bhadeshia and DebRoy 2009). The steel heating coil on top of an electric stove is an example of heating due to the resistance to the flow of the household, 60 Hz electric current. In a similar manner, the heat produced in a part in an induction coil is due to the electrical current circulating in the part (Robson, Kamp, and Sullivan 2007).