Topic
Fresnel zone
About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.
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20 Feb 2021
TL;DR: In this article, a 2D detector and an off-axis Fresnel zone plate are used to image the sample in one spatial dimension and provide spectroscopic information in the other dimension.
Abstract: Soft x-ray spectroscopy is invaluable for gaining insight into quantum materials. However, it is typically conducted in a spatially averaging way, making it blind to inhomogeneity in samples. Here, we demonstrate how we couple imaging to x-ray absorption spectroscopy and resonant inelastic x-ray scattering. Accordingly, we use a 2D detector and an off-axis Fresnel zone plate that images the sample in one spatial dimension and provides spectroscopic information in the other dimension. With our setup, we envision to enable a more detailed understanding of how the behavior of microscopic domains determines the functionality of quantum materials.
7 citations
TL;DR: In this article, the first step of a Fourier expansion is used to calculate particle velocities induced by disc-shaped transducers which are assumed perfectly damped and excited by a step wise function.
7 citations
01 May 2019
TL;DR: A measurement solution and image reconstruction algorithms using radio-frequency tomography to determine the position of a man in closed rooms using Bluetooth 4.0 Low Energy signals and devices emitting radio signals.
Abstract: The article presents a measurement solution and image reconstruction algorithms using radio-frequency tomography. In this method, the action requires measuring the strength of the radio signal between the transmitter and the receiver. The under pressure of the measurement value of the signal strength changes as a result of the absorption, reflection or dissipation of electromagnetic waves. Radio tomography can determine the position of a man in closed rooms. It can be used for navigation and locating inside buildings. The solution works on the basis of Bluetooth 4.0 Low Energy signals and devices emitting radio signals.
7 citations
TL;DR: In this paper, the results of calculations on the optical properties of zone plates at grazing incidence angles are presented, and the diffraction integrals for the Fresnel zone geometries are shown to be similar at normal and grazing incidence angle.
Abstract: The results of calculations on the optical properties of zone plates at grazing incidence angles are presented. In terms of the diffraction theory, the diffraction integrals for the Fresnel zone geometries are shown to be similar at normal and grazing incidence angles in the Fresnel approximation. One-dimensional and two-dimensional cases are discussed.
7 citations
17 May 2004
TL;DR: In this paper, a coherent reflection component is voluntarily imposed over incoherent components, resulting in a large value of Rician factor, especially under small sea wave height or calm sea conditions.
Abstract: Empirical analyses, based on extensive measurements results, were performed to characterize maritime radio propagation in the GSM1800 frequency band. As the height of sea waves increases, it blocks more of the Fresnel zones below the line-of-sight path. It is of interest, therefore, to examine the overall statistics of the received signal in rough sea surface conditions. The overall statistics of the received signal was found to be properly represented by a mixture of the Rician and log-normal distributions with varying Rician factor and standard deviation. From our observations, a coherent reflection component is voluntarily imposed over incoherent components, resulting in a large value of Rician factor, especially under small sea wave height or calm sea conditions. Fading depth and intensity were also evaluated. The BER performance, corresponding to these sea surface profiles, were analyzed by computer simulation.
7 citations