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Point source

About: Point source is a research topic. Over the lifetime, 5077 publications have been published within this topic receiving 94091 citations.


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TL;DR: In this article, the identification of a time-dependent point source occurring in the right-hand side of a one-dimensional evolution linear advection-dispersion-reaction equation is investigated.
Abstract: This paper deals with the identification of a time-dependent point source occurring in the right-hand side of a one-dimensional evolution linear advection–dispersion–reaction equation. The originality of this study consists in considering the general case of transport equations with spatially varying dispersion, velocity and reaction coefficients which enables to extend the applicability of the obtained results to various areas of science and engineering. We derive a main condition on the involved spatially varying coefficients that yields identifiability of the sought source, provided its time-dependent intensity function vanishes before reaching the final monitoring time, from recording the generated state at two observation points framing the source region. Then, we establish an identification method that uses those records to determine the elements defining the sought source. Some numerical experiments on a variant of the surface water pollution model are presented.

27 citations

Journal ArticleDOI
TL;DR: In this paper, the surface charge distribution (SCD) method was proposed to solve the quasi-static limit of a modeling method for radio frequency (RF) electrical sensors of any shape, including their real environment, in isotropic and uniform plasma.
Abstract: This paper presents the general theory in the quasi-static limit of a modeling method for radio frequency (RF) electrical sensors of any shape, including their real environment, in isotropic and uniform plasma. This is particularly applicable to plasma probes and antennas installed on board spacecraft for purposes such as natural wave investigations and thermal plasma diagnostics. We propose to use the surface-charge distribution (SCD) method, which involves the assumption that all boundary surfaces under consideration, including spacecraft structures and ion sheath interfaces, are submitted to the RF electrostatic equilibrium imposed by the kinetic plasma. The resulting real and fictitious charges are assumed to be distributed among infinitesimal surface elements, so that each of them can be considered as a single pulsating point source. The well-known difficulties with the conventional induced electromotive force (emf) method when the current distribution is not trivial are skirted here since the Green function is solved once and for all in the case of single point source. The problem amounts to solving a set of linear equations resulting from boundary conditions imposed by surface potentials, external fields, and network interconnections. In a companion paper, we present an application of the SCD numerical method to an actual space experiment.

27 citations

Journal ArticleDOI
TL;DR: In this paper, two methods of improving the quality of three-dimensional beamforming with phased microphone arrays were examined and compared for the detection of aerodynamic noise sources on wind turbines.

27 citations

Journal ArticleDOI
01 Jan 1995-Micron
TL;DR: In this article, the setup of the LEEPS (low energy electron point source) microscope is described and images of carbon fibres and nanotubes are shown and compared to simulated images.

27 citations

Journal ArticleDOI
TL;DR: The accuracy and computational efficiency of the developed scheme make this algorithm a suitable candidate for its deployment in real-time localization of radioactive sources, and the error in source localization was primarily due to detection uncertainties.
Abstract: Radioactive source localization plays an important role in tracking radiation threats in homeland security tasks. Its real-time application requires computationally efficient and reasonably accurate algorithms even with limited data to support detection with minimum uncertainty. This paper describes a statistic-based grid-refinement method for backtracing the position of a gamma-ray source in a three-dimensional domain in real-time. The developed algorithm used measurements from various known detector positions to localize the source. This algorithm is based on an inverse-square relationship between source intensity at a detector and the distance from the source to the detector. The domain discretization was developed and implemented in MATLAB. The algorithm was tested and verified from simulation results of an ideal case of a point source in non-attenuating medium. Subsequently, an experimental validation of the algorithm was performed to determine the suitability of deploying this scheme in real-time scenarios. Using the measurements from five known detector positions and for a measurement time of 3 min, the source position was estimated with an accuracy of approximately 53 cm. The accuracy improved and stabilized to approximately 25 cm for higher measurement times. It was concluded that the error in source localization was primarily due to detection uncertainties. In verification and experimental validation of the algorithm, the distance between 137 Cs source and any detector position was between 0.84 m and 1.77 m. The results were also compared with the least squares method. Since the discretization algorithm was validated with a weak source, it is expected that it can localize the source of higher activity in real-time. It is believed that for the same physical placement of source and detectors, a source of approximate activity 0.61–0.92 mCi can be localized in real-time with 1 s of measurement time and same accuracy. The accuracy and computational efficiency of the developed scheme make this algorithm a suitable candidate for its deployment in real-time localization of radioactive sources.

27 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202350
2022133
2021103
2020135
2019123
2018133