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Petroleum Seismological Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Additionally the ‘attenuation coefficient’ may be defined as a measure of the ratio of the decrease in the intensity of a wave during propagation to the incident energy. It is the fraction of incident wave energy absorbed per unit mass or thickness of the medium. Reflection coefficient is the ratio of amplitude of the incident wave to the amplitude of the reflected wave.
PLC cabling, data transmission, and networking
Published in Raymond F. Gardner, Introduction to Plant Automation and Controls, 2020
Modbus technology was developed during the first generations of PLCs and is so robust and reliable that it is still very commonly used in plant controls, even after more than five decades of technology advancements. Modbus is a versatile, easy-to-use, and hearty means of transmitting data over long or short distances. Modbus RS485 uses a serial data link, where the RS485-device cables are daisy-chained from one controller to the next (Figure 18.12). Failure of any device in the string does not interrupt the daisy chain wiring circuit, and all remaining devices continue to communicate. For relatively long runs, the signal conductors at each end of the RS485 daisy chain are connected through terminating resistors, in order to match the cable impedance to the impedance required by the hardware (Figure 18.13). Impedance matching is necessary to avoid signal reflections that would be very problematic at high data-transmission rates. Signal reflections can also distort the original signal, reducing reliability.
Waves and electromagnetic radiation
Published in Andrew Norton, Dynamic Fields and Waves, 2019
The law of reflection states that when a wave strikes a reflecting surface, the incident and reflected rays and the normal to the surface all lie in the same plane, and the angle of incidence equals the angle of reflection.
Automated variance modeling for three-dimensional point cloud data via Bayesian neural networks
Published in IISE Transactions, 2023
Zhaohui Geng, Arman Sabbaghi, Bopaya Bidanda
The variance of each point on an object is strongly affected by the object’s geometric descriptors and its interactions with the light source and/or ambient light. Although parts can range across an infinite variety of designs in principle, the nature of non-contact scanners implies that only local geometric information affects the variance of a point on a part. In the specific case of a laser scanner, the shape of the local area in which the laser is projected significantly impacts the variability of the extracted point coordinates. This corresponds to the basic mechanism of a general laser scanner for inferring the coordinates of a point on the object surface by receiving the reflection of the laser strip projected on the camera receiver (Figure 3). The Law of Reflection states that the angle of incidence θi should equal the angle of reflection θr (Pedrotti et al., 2017). Therefore, if the incident laser is nearly orthogonal to the normal direction for a point, then it becomes difficult to capture its reflection by the camera, which may increase the measurement variance. Furthermore, it is difficult to accurately measure high-curvature points via the laser stripe. This is because high-curvature points are generally located in small regions that are difficult to capture by the laser stripes, and also because the tangent planes and normals of these points are relatively more sensitive to noise, due to the high curvature.
Soil-Structure-Interaction using Cone Model in Time Domain for Horizontal and Vertical Motions in Layered Half Space
Published in Journal of Earthquake Engineering, 2020
Mehran Khakpour, Masoud Hajialilue Bonab
In the multilayered semi-infinite mode, wave propagation mechanism in the initial cone in the interface between layers will be influenced. When the propagated wave in the initial cone encounters with the interface between two layers, a reflected wave with upward propagation and a refracted wave with downward propagation are generated (Figure (2)). Each of these waves propagates inside its own cone as a new incident wave, which will face the discontinuity of the materials in the next step. The parameters of these secondary cones are determined with respect to the characteristics of the soil layer materials, which the wave will propagate inside them. The interface between two layers can be considered as a new source of disturbance, and modeled with an imaginary disk. Reflected and refracted waves amplitude can be determined by the coefficient of reflection as a function of incident wave amplitude. Reflection coefficient is denoted as the ratio of reflected wave to incident wave. Concerning the compatibility of displacement and equilibrium of the interface between two layers, cumulative amplitude of the incident and reflected waves tallies with amplitude of the refracted wave in the second material, which leads to the subsequent equation (Wolf and Deeks, 2004):
Morphological Box Classification Framework for supporting 3D scanner selection
Published in Virtual and Physical Prototyping, 2018
W. L. K. Nguyen, A. Aprilia, A. Khairyanto, W. C. Pang, G. G. L. Seet, S. B. Tor
When an optical wave reflects off any surface, there are two forms of reflection, which are specular and diffuse reflection. Specular reflection is the mirror-like reflection of waves, where the incident ray and reflected ray have the same angle to the surface normal. Diffuse reflection is the reflection of waves in many directions, or angles, due to the scattering of the waves. When scanning a typical surface, the receiver usually captures a reflected wave reflected by diffuse reflection, as the receiver is seldom at the same angle away from the surface normal as the optical source. However, in the case of a reflective surface, the specular reflection is the dominant form of reflection, with little diffuse reflection (Figure 1(e)). This leads to little or no reflected energy captured by the receiver, and cause the same problem as black or dark-coloured surfaces.