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Neutron tomography data collected with MCP detector (soil specimen)
No full textNeutron tomography data collected with MCP detector in July 2016 at the ISIS Neutron Spallation Source, UK as part of the scientific commissioning of the neutron imaging beamline, IMAT. Different projection angles were acquired over an angular range of 180° (first 41 projections with angular step of 3° and the last 14 projections with angular step of 4°).</span
Correlative X-ray and neutron tomography of root systems using cadmium fiducial markers
No full textThe interactions between plant roots and soil are an area of active research, particularly in terms of water and nutrient uptake. Because noninvasive, in vivo studies are required, tomographic imaging appears an obvious method to use, but no one imaging modality is well suited to capture the complete system. X‐ray imaging gives clear insight to soil structure and composition; however, water is comparatively transparent to X‐rays and biological matter also displays poor contrast with respect to the pores between soil particles. Neutron imaging presents a complementary view where water and biological matter are better distinguished but the soil minerals are not imaged as clearly as they would be with X‐rays.This work aims to develop robust methods for complementary X‐ray/neutron tomographic imaging of plant root samples which should lead to new insight into water and nutrient transport in soil. The key challenges of this project are to develop experiments that will meet the requirements of both imaging modalities as well as the biological requirements of the plant samples and to develop ways to register a pair of reconstructed volume images of a sample that will typically have been produced with entirely separate facilities. The use of cadmium fiducial markers for registration has been investigated. Simulations were conducted to investigate the expected registration accuracy as the quantity and distribution of the markers varied. The findings of these simulations were then tested experimentally as plant samples were grown and imaged using neutrons with the IMAT instrument at ISIS Neutron and Muon Source at the STFC Rutherford Appleton Laboratory in Harwell, and with X‐rays at µ‐VIS X‐ray Imaging Centre at the University of Southampton
Data Supporting PhD thesis: Development of correlative neutron and X-ray computed tomography to study fluid dynamics and structural deformation at the micro-scale in plant and soil systems
No full textThe datasets (Raw X-ray and neutron CT data and subsequent processing scripts) relating to the work carried out in the named thesis</span
Correlative neutron and X-ray tomography imaging of pile installation in chalk
No full textNeutron and X-ray tomography (NCT and XCT, respectively) are imaging techniques increasingly being applied in geomechanics research. They are used to non-destructively reveal different microstructural aspects of geomaterials: XCT is often used to observe/quantify differences in density or porosity, while NCT reveals the presence and distribution of hydrogenous materials such as water. The correlated use of NCT and XCT for geomechanics and geotechnics research is in its infancy. To this date, very few experiments have been carried out that combine both techniques, and none have been used to investigate geomaterial-structure interaction. This paper presents the first correlative NCT-XCT imaging study of pile installation. A scaled model pile was installed in an unsaturated intact chalk cylinder and in-situ NCT and ex-situ XCT synchrotron-based imaging was applied consecutively. Chalk was used because the behaviour of displacement piles installed in this material is still subject to considerable uncertainty. Results reveal for the first time the interaction between installation-induced changes in chalk density and water distribution variations, with evidence of water displacement into the densified material in the vicinity of the installed pile. A straightforward method for correlative bulk density-moisture content determination from NCT-XCT images of geomaterials are presented and their limitations discussed
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Combined Neutron Imaging and Diffraction: Instrumentation and Experimentation
Full text linkA combined neutron imaging and diffraction facility, IMAT (Imaging and Materials Science & Engineering) is developed at ISIS (Target Station 2).
One subject of this thesis was focused on the design and optimization of the imaging part of IMAT, using the Monte Carlo calculation software package McStas. Hence, the neutron guide dimensions, the effects of the gaps in the neutron guide on imaging detectors, gravitation effects in the neutron guide and also the influence of the pinhole size on the image were studied. All these investigations were made taking into account the most important design criteria: to maximise the neutron flux, to obtain a good energy resolution whilst retaining a large neutron bandwidth and a long flight path and to minimize the artefacts obtained in the neutron radiographies.
After a compromise between imaging, diffraction and engineering requirements had been reached, the results from simulations specific to the current IMAT design were studied: wavelength distribution, beam profiles at different points along the beamline, beam divergence, neutron intensity distribution and flux depending on the pinhole size and the wavelength bands. Moreover, generation of IMAT imaging data with a sample led to full tomographic simulations and modelling wavelength effects.
Another objective of the thesis was to study the complementarity between neutron imaging and neutron diffraction experiments. For this, a new instrument control concept that exploits tomography data to guide diffraction experiments on samples with complex structures and shapes named “tomography driven diffraction” (henceforth, TDD) was developed. The method has been proved to be viable using combinations of individual tomography and diffraction instruments: NEUTRA (PSI) and ENGIN-X (ISIS) for different samples drawn from the engineering and heritage sciences. On IMAT it will be possible to perform tomography, mark the measurement points and proceed to the diffraction measurements as one continuous process
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Neutron tomography data collected with MCP detector (soil specimen)
No full text<p>Neutron tomography data collected with MCP detector in July 2016 at the ISIS Neutron Spallation Source, UK as part of the scientific commissioning of the neutron imaging beamline, IMAT.</p>
<p>Different projection angles were acquired over an angular range of 180° (first 41 projections with angular step of 3° and the last 14 projections with angular step of 4°).</p>
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