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Physics for medical imaging
Published in Ken Holmes, Marcus Elkington, Phil Harris, Clark's Essential Physics in Imaging for Radiographers, 2021
As such it can be measured and classified by its wavelength and frequency. The electromagnetic spectrum includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays (Figure 3.8).
Epilogue
Published in R. Kurt Barnhart, Douglas M. Marshall, Eric J. Shappee, Introduction to Unmanned Aircraft Systems, 2021
The command and control (C2) components comprise the UAS subsystem that enables controllable and autonomous flight. An essential C2 element is human, and the term operator “in the loop” implies direct control of the vehicle through pilot intervention, and operator “on the loop” indicates that the operator is monitoring autonomous flight. Other components most generally comprising the C2 subsystem are the ground control station (GCS) and associated software and electronics, antennae, ground-based and airborne transceivers, the autopilot to enable autonomous flight, air data and GPS systems, MEMS gyros, accelerometers and magnetometers for navigation and vehicle control, the interconnecting circuits and data buses, and onboard intelligences for computing and data processing. Larger UASs may also include auto-takeoff and autolanding systems. Although UAS command and control may occur via other methods (e.g., light transmission or through the umbilical cable of a tethered vehicle), C2 is most commonly accomplished via two-way transmissions that communicate commands to the UAS through an uplink and telemetry from the aircraft to the GS through the downlink. The medium through which this communication is accomplished is the radio frequency (RF) portion of the electromagnetic spectrum.
Introduction—Electricity’s Attributes
Published in Clark W. Gellings, 2 Emissions with Electricity, 2020
Electricity, or more precisely electromagnetic energy, is the only energy form which can provide a “gateway” to the electromagnetic spectrum. The electromagnetic spectrum is the range of all frequencies of electromagnetic radiation.
Investigating the electromagnetic shielding effectiveness of copper/cotton full Milano and 1 × 1 rib weft-knitted fabrics
Published in The Journal of The Textile Institute, 2019
Hamed Mohammadi Mofarah, Saeed Shaikhzadeh Najar, Seyed Mohammad Etrati
The electromagnetic spectrum starts from low-frequency electromagnetic waves, and ends with X-rays, and gamma rays. Figure 1 is a schematic representation of the spectrum of electromagnetic waves. A schematic model for transmission of electromagnetic (EM) waves through a homogeneous object is shown in Figure 2. According to the model, it can be seen that there are three different states that determine how the EM field strength is losing due to its interaction with the object: absorption, reflection and transmission attenuation (Roh, Chi, Kang, & Nam, 2008).