China
Africa
Explore chapters and articles related to this topic
Further Studies of Electromagnetic Waves in Cylindricals Geometries
Published in Guillermo Gonzalez, Advanced Electromagnetic Wave Propagation Methods, 2021
The physical interpretation of (9.1.31) is shown in Fig. 9.2. The figure shows two rays incident on the surface at π/2 and −π/2, respectively. Details of the upper ray as it travels to the observation point are shown. The ray travels a distance a[π/2−ϕ−cos−1(a/ρ)] along the surface of the cylinder, and then a distance ρ2−a2, after leaving the surface, to the observation point P. A similar analysis applies to the lower ray. These waves that travel along the cylinder surface and produce the field in the shadow region are known as “creeping waves.” The imaginary part of the roots νp account for the attenuation of these waves.
Optimized design and performance analysis of wearable antenna sensors for wireless body area network applications
Published in Journal of Information and Telecommunication, 2023
Abdelaziz Hamdi, Amina Nahali, Mokhtar Harrabi, Rafik Brahem
Investigating the electromagnetic radiation effect on the human body surface is an essential issue specifically for the medical applications because of possible short and long-term health consequences and for risk factor associated constraints. Based on simulation results, this is a huge challenge because the wavelength of signal λs is much smaller than the normal size of the human body, leading to the requirement of infinitesimal discretization of complex geometrical structures and then the need of computational resources due to the long execution times. For these reasons, in our numerical study, the Finite Integration Technique (FIT) technique associated with CST-MWS simulator is employed for the methodology. It consists of studying the feasibility of creeping-wave simulation of field absorption at Industrial, Scientific, and Medical (ISM) frequencies, for numerical methods applied to the electromagnetic domain and geometries in the order of a human body with a specific size.
Simulation and experimental study on planar remote field eddy current detection of hidden defects in aircraft multilayer structure
Published in Nondestructive Testing and Evaluation, 2023
Kai Song, Shaodong Fu, Ning Ning, Junling Fan, Ximing Cui
At present, extensive research has been carried out on the non-destructive testing of aircraft multi-layer flat structures. Zhi WQ [6] used the ultrasonic creeping wave detection technology to detect and image the open crack defect on the surface of the cylindrical through hole of the fastening assembly under the condition of non-disassembly. However, the ultrasonic creeping wave has a low sensitivity to the detection of closed cracks, and the imaging effect of the crack defect shape needs to be improved. Tian YF [7] applied infrared detection technology to the detection of aircraft skin overlapping structure, and identified the internal defects of overlapping components by abnormal temperature field, but strong excitation heat source was needed. Stott CA [8] combined the pulsed eddy current detection technology and the improved principal component analysis algorithm to analyse the corresponding signals of the defects and realise the crack detection and quantitative evaluation of the fasteners. However, due to the skin effect, the detection depth is limited. Although scholars have carried out relevant experimental studies, due to the complex structure of the multi-layer plate, there are many problems in the conventional detection method, and it is difficult to detect the complex defects inside the multi-layer plate.
Geometry based parameter extraction and creeping wave evaluation for triangulated convex surfaces
Published in Waves in Random and Complex Media, 2022
Studies on extraction of some geometry based parameters exist in the literature [12–17]. An algorithm was proposed for fast approximation of geodesic distance or path length from a meshed surface consisting of polygons [12], but it is not sufficiently accurate for UTD applications. Existing curvature and torsion extraction studies are limited to planar and spatial curves [13], or are directed to smoothing of triangulated surfaces [14]. A comprehensive survey of the studies on extraction of quadric surfaces from triangulated surfaces was presented [15]. However, the algorithms proposed in this survey for extracting principal directions and curvatures are based on predicting surface normal vectors at vertices of triangular facets, and these studies target shape recovery applications. Another study focuses on extraction of principal directions from triangulated surfaces using a different quadratic surface representation [16]. A graphical processing unit (GPU) based real-time curvature extraction was also proposed [17], but it only estimates curvature tensor at vertices of triangular facets. These studies [12–17] target computer graphics applications such as shape recovery and surface smoothing. They are not suitable for UTD applications without significant modifications or improvements since they do not extract these parameters for a specific direction at a point on a meshed surface. In addition, they either use a different quadratic surface representation or do not use such a representation at all. There are also studies on application of UTD creeping wave solutions to discretized surfaces [18–22]. However, these studies do not involve extraction of geometry based parameters, and evaluation of surface fields for source and field points on a convex surface. Therefore, there is a gap in the literature in terms of availability of approaches for accurate and efficient extraction of geometry based parameters from meshed convex surfaces based on quadratic surface mapping in barycentric coordinates as well as application of the UTD solution for mutual coupling [1–3] to these surfaces using the extracted parameters.