3,724 research outputs found
Device Free Localisation Techniques in Indoor Environments
The location estimation of a target for a long period was performed only by device based localisation technique which is difficult in applications where target especially human is non-cooperative. A target was detected by equipping a device using global positioning systems, radio frequency systems, ultrasonic frequency systems, etc. Device free localisation (DFL) is an upcoming technology in automated localisation in which target need not equip any device for identifying its position by the user. For achieving this objective, the wireless sensor network is a better choice due to its growing popularity. This paper describes the possible categorisation of recently developed DFL techniques using wireless sensor network. The scope of each category of techniques is analysed by comparing their potential benefits and drawbacks. Finally, future scope and research directions in this field are also summarised
Isotropic inverse-problem approach for two-dimensional phase unwrapping
In this paper, we propose a new technique for two-dimensional phase
unwrapping. The unwrapped phase is found as the solution of an inverse problem
that consists in the minimization of an energy functional. The latter includes
a weighted data-fidelity term that favors sparsity in the error between the
true and wrapped phase differences, as well as a regularizer based on
higher-order total-variation. One desirable feature of our method is its
rotation invariance, which allows it to unwrap a much larger class of images
compared to the state of the art. We demonstrate the effectiveness of our
method through several experiments on simulated and real data obtained through
the tomographic phase microscope. The proposed method can enhance the
applicability and outreach of techniques that rely on quantitative phase
evaluation
Characterising encapsulated nuclear waste using cosmic-ray muon tomography
Tomographic imaging techniques using the Coulomb scattering of cosmic-ray
muons have been shown previously to successfully identify and characterise low-
and high-Z materials within an air matrix using a prototype scintillating-fibre
tracker system. Those studies were performed as the first in a series to assess
the feasibility of this technology and image reconstruction techniques in
characterising the potential high-Z contents of legacy nuclear waste containers
for the UK Nuclear Industry. The present work continues the feasibility study
and presents the first images reconstructed from experimental data collected
using this small-scale prototype system of low- and high-Z materials
encapsulated within a concrete-filled stainless-steel container. Clear
discrimination is observed between the thick steel casing, the concrete matrix
and the sample materials assayed. These reconstructed objects are presented and
discussed in detail alongside the implications for future industrial scenarios.Comment: 6 pages, 4 figure
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