Dynamic image analysis for three-dimensional particle shape characterisation

Particulate matter is ubiquitous in numerous industries, from energy storage to medicine, with many industrial processes being increasingly dependent on understanding particulate matter on a finer scale. As real particles have such a large variation in morphology, it is crucial to characterise them at scale, accurately, and in real-time. Current industrial standards are limited to 2D analysis of dynamic particulates or 3D analysis of static particulates, using technologies such as digital microscopy or X-ray CT scanner, respectively. The combination of several 2D images projected from different perspectives allows for 3D reconstruction and 3D characterisation of particle morphology. A real-time shape analysis is performed to classify particles with a higher degree of accuracy. Via use of these projections, several camera orientations have been set up in order to find the orientation of perspectives that provides the highest degree of accuracy with the lowest cost in creating 3D avatars of particles. In order to show the benefits of 3D analysis over 2D analysis, irregular particles of dolomite, silica sand, and waste glass beads are tested and compared with X-ray CT images. This study allows for a broad range of different morphological indices to be investigated and for the level of characterisation error to be quantified

How Do Roots Interact with Layered Soils?

Vegetation alters soil fabric by providing biological reinforcement and enhancing the overall mechanical behaviour of slopes, thereby controlling shallow mass movement. To predict the behaviour of vegetated slopes, parameters representing the root system structure, such as root distribution, length, orientation and diameter, should be considered in slope stability models. This study quantifies the relationship between soil physical characteristics and root growth, giving special emphasis on (1) how roots influence the physical architecture of the surrounding soil structure and (2) how soil structure influences the root growth. A systematic experimental study is carried out using high-resolution X-ray micro-computed tomography (\ub5CT) to observe the root behaviour in layered soil. In total, 2 samples are scanned over 15 days, enabling the acquisition of 10 sets of images. A machine learning algorithm for image segmentation is trained to act at 3 different training percentages, resulting in the processing of 30 sets of images, with the outcomes prompting a discussion on the size of the training data set. An automated in-house image processing algorithm is employed to quantify the void ratio and root volume ratio. This script enables post processing and image analysis of all 30 cases within few hours. This work investigates the effect of stratigraphy on root growth, along with the effect of image-segmentation parameters on soil constitutive properties

A Python implementation of CLUMP, the Code Library to generate Universal Multi-sphere Particles

Multi-spheres are widely employed to model non-spherical particles in the Discrete Element Method. For the past three years, the CLUMP code has provided the means to compare different multi-sphere particle generation methods in a quantitative manner, via the implementation of different particle generation methods within a single software package. This paper reports on the evolution of the software, underpinned by the following recent developments: (1) a Python implementation of CLUMP, which is maintained alongside the original MATLAB code, and (2) the extension of the Euclidean transform method proposed in the original CLUMP paper to bonded and crushable particles. The new Python implementation and feature development enhance the accessibility of the software to a wider user base and generalize its applicability to a more diverse set of problems

Controlling fragment size distribution for modelling the breakage of multi-sphere particles

Voro-Pack, an open-source code is introduced to reconstruct real particles into multi-sphere clusters consisting of fragments with controlled size distributions, enabling experiment-informed fragment size distributions (FSD). Two types of silica sand are employed to evaluate the performance of the code, where FSD data are obtained through laser diffraction and sieving, and particle shape information is obtained through micro computed tomography. The results show that the particle sizes and shapes of the multi-sphere clusters generated by the code are in good agreement with those of real particles. It is found that the fragment sizes in the multi-sphere clusters aligned more closely with the real FSD data when laser diffraction data were used as input, compared to sieving. The volume ratio of the multi-sphere clusters to the actual particles is a key factor influencing the size distribution of fragments, with better matching to the actual FSD data when the volume ratio exceeds 0.5 and approaches 1.0. Additionally, the particle shape characteristics do not significantly affect the FSD data in the code-generated clusters. These findings suggest that the Voro-Pack code is an effective tool in reconstructing multi-sphere clusters for particles of various morphologies, providing valuable insights into modelling the breakage of granular materials

Search for flavour-changing neutral currents in processes with one top quark and a photon using 81 fb−1 of pp collisions at s=13TeV with the ATLAS experiment

A search for flavour-changing neutral current (FCNC) events via the coupling of a top quark, a photon, and an up or charm quark is presented using 81 fb−1 of proton–proton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Events with a photon, an electron or muon, a b-tagged jet, and missing transverse momentum are selected. A neural network based on kinematic variables differentiates between events from signal and background processes. The data are consistent with the background-only hypothesis, and limits are set on the strength of the tqγ coupling in an effective field theory. These are also interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tuγ coupling of 36 fb (78 fb) and on the branching ratio for t→γu of 2.8×10−5 (6.1×10−5). In addition, they are interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tcγ coupling of 40 fb (33 fb) and on the branching ratio for t→γc of 22×10−5 (18×10−5)

Measurement of W± boson production in Pb+Pb collisions at √sNN=5.02Te with the ATLAS detector

A measurement of W± boson production in Pb+Pb collisions at sNN=5.02Te is reported using data recorded by the ATLAS experiment at the LHC in 2015, corresponding to a total integrated luminosity of 0.49nb-1. The W± bosons are reconstructed in the electron or muon leptonic decay channels. Production yields of leptonically decaying W± bosons, normalised by the total number of minimum-bias events and the nuclear thickness function, are measured within a fiducial region defined by the detector acceptance and the main kinematic requirements. These normalised yields are measured separately for W+ and W- bosons, and are presented as a function of the absolute value of pseudorapidity of the charged lepton and of the collision centrality. The lepton charge asymmetry is also measured as a function of the absolute value of lepton pseudorapidity. In addition, nuclear modification factors are calculated using the W± boson production cross-sections measured in pp collisions. The results are compared with predictions based on next-to-leading-order calculations with CT14 parton distribution functions as well as with predictions obtained with the EPPS16 and nCTEQ15 nuclear parton distribution functions. No dependence of normalised production yields on centrality and a good agreement with predictions are observed for mid-central and central collisions. For peripheral collisions, the data agree with predictions within 1.7 (0.9) standard deviations for W- (W+) bosons

Z boson production in Pb+Pb collisions at √Snn = 5.02 TeV measured by the ATLAS experiment

The production yield of Z bosons is measured in the electron and muon decay channels in Pb+Pb collisions at √S = 5.02 TeV with the ATLAS detector. Data from the 2015 LHC run corresponding to an integrated luminosity of 0.49 nb are used for the analysis. The Z boson yield, normalised by the total number of minimum-bias events and the mean nuclear thickness function, is measured as a function of dilepton rapidity and event centrality. The measurements in Pb+Pb collisions are compared with similar measurements made in proton-proton collisions at the same centre-of-mass energy. The nuclear modification factor is found to be consistent with unity for all centrality intervals. The results are compared with theoretical predictions obtained at next-to-leading order using nucleon and nuclear parton distribution functions. The normalised Z boson yields in Pb+Pb collisions lie 1-3σ above the predictions. The nuclear modification factor measured as a function of rapidity agrees with unity and is consistent with a next-to-leading-order QCD calculation including the isospin effect. nn -

Combination of searches for Higgs boson pairs in pp collisions at s=13TeV with the ATLAS detector

This letter presents a combination of searches for Higgs boson pair production using up to 36.1 fb−1 of proton–proton collision data at a centre-of-mass energy s=13 TeV recorded with the ATLAS detector at the LHC. The combination is performed using six analyses searching for Higgs boson pairs decaying into the bb¯bb¯, bb¯W+W−, bb¯τ+τ−, W+W−W+W−, bb¯γγ and W+W−γγ final states. Results are presented for non-resonant and resonant Higgs boson pair production modes. No statistically significant excess in data above the Standard Model predictions is found. The combined observed (expected) limit at 95% confidence level on the non-resonant Higgs boson pair production cross-section is 6.9 (10) times the predicted Standard Model cross-section. Limits are also set on the ratio (κλ) of the Higgs boson self-coupling to its Standard Model value. This ratio is constrained at 95% confidence level in observation (expectation) to −5.0<κλ<12.0 (−5.8<κλ<12.0). In addition, limits are set on the production of narrow scalar resonances and spin-2 Kaluza–Klein Randall–Sundrum gravitons. Exclusion regions are also provided in the parameter space of the habemus Minimal Supersymmetric Standard Model and the Electroweak Singlet Model