Zeitschriftenartikel zum Thema „Visualisation de gradient“
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Ashe, Hilary L. „BMP Signalling: Visualisation of the Sog Protein Gradient“. Current Biology 12, Nr. 8 (April 2002): R273—R275. http://dx.doi.org/10.1016/s0960-9822(02)00798-4.
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Harvey, Steven A., und James C. Smith. „Visualisation and Quantification of Morphogen Gradient Formation in the Zebrafish“. PLoS Biology 7, Nr. 5 (05.05.2009): e1000101. http://dx.doi.org/10.1371/journal.pbio.1000101.
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Wedge, Daniel, Yathunanthan Sivarajah, Eun-Jung Holden, Peter Kovesi, Chris Wijns und Paul Johnston. „Mass anomaly visualisation and depth estimation from full tensor gradient gravity data“. ASEG Extended Abstracts 2013, Nr. 1 (Dezember 2013): 1–5. http://dx.doi.org/10.1071/aseg2013ab152.
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Hyde, Georgia, Andrew Fry, Ashok Raghavan und Elspeth Whitby. „Biometric analysis of the foetal meconium pattern using T1 weighted 2D gradient echo MRI“. BJR|Open 2, Nr. 1 (November 2020): 20200032. http://dx.doi.org/10.1259/bjro.20200032.
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Objectives: Foetal MRI is used to assess abnormalities after ultrasonography. Bowel anomalies are a significant cause of neonatal morbidity, however there are little data concerning its normal appearance on antenatal MRI. This study aims to investigate the pattern of meconium accumulation throughout gestation using its hyperintense appearance on T1 weighted scans and add to the current published data. Methods: This was a retrospective cohort study in a tertiary referral clinical MRI centre. Foetal body MRI scans of varying gestational ages were obtained dating between October 2011 and March 2018. The bowel was visualised on T1 weighted images. The length of the meconium and the width of the meconium at the rectum, sigmoid colon, splenic flexure and hepatic flexure was measured. Presence or absence of meconium in the small bowel was noted. Inter- and intrarater reliability was assessed. Results: 181 foetal body scans were reviewed. 52 were excluded and 129 analysed. Visualisation of the meconium in the large bowel became increasingly proximal with later gestations, and small bowel visualisation was greater at earlier gestations. There was statistically significant strong (r = 0.6–0.8) or very strong (r = 0.8–1.0) positive correlation of length and width with increasing gestation. Interrater reliability was moderate to excellent (r = 0.4–1.0). Conclusion: This study provides new information regarding the pattern of meconium accumulation throughout gestation. With care, the results can be used in clinical practice to aid diagnosis of bowel pathology. Advances in knowledge: The findings of this study provide further information concerning the normal accumulation of foetal meconium on MR imaging, an area where current research is limited.
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Wołosz, Krzysztof J., und Jacek Wernik. „Air Evacuation from the Pressure Accumulator during Work Cycle of the Pneumatic Pulsator“. Applied Mechanics and Materials 797 (November 2015): 327–33. http://dx.doi.org/10.4028/www.scientific.net/amm.797.327.
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Practically Applicable Vessel Evacuation is Presented in the Article. the Pressure Accumulatoris a Vessel which is a Part of the Pneumatic Pulsator which is Used for Unclogging Outlets of Silos. Apseudo-Schlieren Visualisation Method of Density Gradient and Values of Mach Number are Shown.There is Also a Time Variation of Outflow Velocity Analysed. Airflow Fluctuates after Time of 50 Ms.The Main Reason could Be the Inertia of the Air Mass and a Large Outlet Diameter Relative to the Mainvessel Dimensions
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Talele, Virendra, Niranjan Sonawane, Omkar Chavan, Akash Divate, Niraj Badhe, Mirza Adil Ansar Beg und Harshal Patil. „Aerodynamic Flow Visualisation Over Surfaces Using Smoke Separation Method from Ansys Fluent“. International Journal of Innovative Science and Research Technology 5, Nr. 7 (16.07.2020): 32–35. http://dx.doi.org/10.38124/ijisrt20jul108.
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In the present study, three workbench problem for turbulence modeling with high Reynolds number is used to determine the behavior of fluid flow around the surfaces. The cases for simulation is developed using Ansys workbench CFD fluent module. The computational results are obtained using solution sets of high Reynolds number with the LagrangianEulerian (LE) approach of point particle tracking system in Nevers stoke RANS Equation. The effect of flow pattern around the surface and its kinetic behavior of fluid is evaluated in post-process method of results. By observation, it has been tabulated that fluid flow separation is arousal at the corner end of all surfaces which happens due to evoking of a large adverse pressure gradient.
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Medved, M. S., S. D. Rud, G. E. Trufanov und D. S. Lebedev. „The intraoperative visualisation technique during lead implantation into the cardiac conductive system: aspects of computed tomography: prospective study“. Diagnostic radiology and radiotherapy 14, Nr. 3 (05.10.2023): 46–52. http://dx.doi.org/10.22328/2079-5343-2023-14-3-46-52.
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INTRODUCTION: The lead implantation into the cardiac conduction system (CCS) is the most physiological method of pacing nowadays. «The method of intraoperative visualization and control of the lead position for permanent electrocardiostimulation during implantation of the lead in the CCS» has been developed for reduce the number of non-targeted implantations. This method based on the integration into the angiograph system 3D-reconstruction of the heart converted to computed tomography (CT) in the form of a mask against the background of fluoroscopy. CT is an important stage of the intraoperative visualization technique (IVT).OBJECTIVE: The aim of the study was to adapt the protocol of CT examination of the heart with contrast to construct a partially segmented 3D-reconstruction of the heart on an angiographic complex for subsequent use during of the lead implantation in the CCS within the framework of the author’s IVT.MATERIALS AND METHODS: As part of the development of the IVT, 21 CT studies of the heart were selected from own database. The step of the gradient of the density difference of the contrasted blood is about 10 HU, the range of the difference of densitometric parameters of the «left ventricle (LV) — right ventricle (RV)» from 0 HU to 200 HU. As well as selected 11 CT studies of the heart. The step of the gradient of the difference of densitometric indicators the contrasted blood in «the RV cavity — myocardium» is about 10 HU, the range is from 0 HU to 100 HU. All CT scans are alternately loaded into the angiograph, followed by the creation of a 3D model of the heart using basic software.RESULTS: It’s necessary to exceed the degree of contrast of the LV cavity over the RV cavity by at least 80 HU to perform partial segmentation on the left and right chambers of a 3D-model of the heart in an angiographic complex that does not have a specialized segmentation module. A sufficiently large part of the left ventricular cavity (LV) disappears with a smaller gradient when the right ventricular cavity (RV) is suppressed. The minimum gradient of «the ventricular cavity — myocardium» is at least 20 HU. The boundaries of the right ventricular edge of the interventricular septum (IVS) are not visualized with a smaller contrast gradient. It’s important for determining the insertion place of the lead into the IVS.CONCLUSION: It’s necessary to exceed the contrast of the LV cavities above the RV cavity by at least 80 HU, the RV cavity above the myocardium by at least 20 HU to perform partial segmentation on the left and right chambers of a 3D-model of the heart in an angiographic complex that does not have a specialized segmentation module
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Hauenstein, Jacob D., und Timothy S. Newman. „Achieving Better Energy Efficiency in Volume Analysis and Direct Volume Rendering Descriptor Computation“. Computers 13, Nr. 2 (13.02.2024): 51. http://dx.doi.org/10.3390/computers13020051.
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Approaches aimed at achieving improved energy efficiency for determination of descriptors—used in volumetric data analysis and one common mode of scientific visualisation—in one x86-class setting are described and evaluated. These approaches are evaluated against standard approaches for the computational setting. In all, six approaches for improved efficiency are considered. Four of them are computation-based. The other two are memory-based. The descriptors are classic gradient and curvature descriptors. In addition to their use in volume analyses, they are used in the classic ray-casting-based direct volume rendering (DVR), which is a particular application area of interest here. An ideal combination of the described approaches applied to gradient descriptor determination allowed them to to be computed with only 80% of the energy of a standard approach in the computational setting; energy efficiency was improved by a factor of 1.2. For curvature descriptor determination, the ideal combination of described approaches achieved a factor-of-two improvement in energy efficiency.
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D, Nivedhidha, und Dr Sujatha B. „Big Data Visualisation of Heart Disease Prediction Using High Level Ada Boosting Algorithm and Gradient Boosting Algorithm“. International Research Journal of Computer Science 11, Nr. 04 (05.04.2024): 204–11. http://dx.doi.org/10.26562/irjcs.2024.v1104.12.
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Machine learning and artificial intelligence have been found useful in various disciplines during the course of their development, especially in the enormous increasing data in recent years. It can be more reliable for making better and faster decisions for disease predictions. So, machine learning algorithms are increasingly finding their application to predict various diseases. Constructing a model can also help us visualize and analyze diseases to improve reporting consistency and accuracy. This article has investigated how to detect heart disease by applying various machine learning algorithms. The study in this article has shown a two-step process. The heart disease dataset is first prepared into a required format for running through machine learning algorithms. Medical records and other information about patients are gathered from the UCI repository. The heart disease dataset is then used to determine whether or not the patients have heart disease. Secondly, Many valuable results are shown in this article. The accuracy rate of the machine learning algorithms, such as Logistic Regression, Support vector machine, K-Nearest-Neighbours, Adaboost, and Gradient Boosting Classifier, are validated through the confusion matrix. Current findings suggest that the Logistic Regression algorithm gives a high accuracy rate of 95% compared to other algorithms. It also shows high accuracy for f 1-score, recall, and precision than the other four different algorithms. However, increasing the accuracy rates to approximately 97% to 100% of the machine learning algorithms is the future study and challenging part of this research.
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Zhao, H., und Q. Hu. „3D RECONSTRUCTION AND RENDERING VISUALIZATION OF TUNNEL POINT CLOUD“. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVIII-3/W1-2022 (27.10.2022): 93–101. http://dx.doi.org/10.5194/isprs-archives-xlviii-3-w1-2022-93-2022.
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Abstract. This paper presents a method for rapid and automatic visualisation of over-undercutting based on 3D reconstruction and rendering of tunnel point clouds. The method uses model filtering and our improved voxel filtering for point cloud lite to maximise the preservation of the original tunnel point cloud features while streamlining the point cloud. The 3D reconstruction is then completed according to our proposed alpha-shape algorithm with low reconstruction parameters combined with a fast model optimisation model, which achieves high reconstruction accuracy while significantly improving computational efficiency to meet the requirements of the tunneling project. The rendering method is calculated by selecting the RGB values. The darker the colour, the heavier the degree of over-excavation or under-excavation. According to the calculated over-excavation or under-excavation value, the ratio of the point in the over-excavation or under-excavation interval is obtained in turn, and the gradient is rendered by increasing the base colour of each interval proportionally; the kd-tree is then introduced to calculate and visualise the colour information of the reconstructed model. In addition, this paper uses real-world tunnel point cloud data and demonstrates that the method meets expectations through qualitative and quantitative evaluation. Visualisation of the tunnel point cloud is accomplished while maintaining speed, visualising the over-under-excavation situation and providing an outlook for future work.
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Varallyay, Peter, Csanad Varallyay, Andrea Horvath, Laszlo Szidonya, Rochelle Fu, Gerda Toth und Edward A. Neuwelt. „Visualisation of normal and abnormal brain vasculature with different ferumoxytol doses.“ Journal of Clinical Oncology 35, Nr. 15_suppl (20.05.2017): e13517-e13517. http://dx.doi.org/10.1200/jco.2017.35.15_suppl.e13517.
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e13517 Background: Ferumoxytol is an iron oxide nanoparticle, marketed for iron replacement therapy. Off label use as an MRI contrast agent allows visualization of cerebral vasculature in the early blood pool phase without early contrast enhancement obscuring the vessels as seen with small molecular gadolinium. This study tested the optimal ferumoxytol dose for visualization of normal and abnormal cerebral vasculature. Methods: MRI images of 75 subjects enrolled in imaging research protocols were analyzed. Vascular visualization was tested in high resolution gradient echo T2*-weighted images acquired after 1mg/kg, 3mg/kg and 7mg/kg (up to 510mg) ferumoxytol doses. Visualization of normal and abnormal vasculature was separately evaluated as “poor, moderate or clear”. Degree of blooming artifact was graded as “none, mild and marked”. Overall clarity of the image was visually assessed as “poor, moderate and very clear”. The probability of abnormal vasculature visualization being “moderate” or “clear” was tested among the three Fe dosages with a mixed effects model while taking correlation among different dosages into account. Results: Visualization of normal brain vasculature was poor with 1mg/kg, moderate with 3mg/kg and very clear with 7mg/kg in 97% of the cases. However, blooming with 7 mg/kg was already marked for all cases causing confluence of larger veins and even smaller vessels close to each other, while images with 3mg/kg showed only mild blooming in all cases, resulting in altogether a better quality/clarity of the images (very clear in 93.3%) with good contrast between normal vessels and brain parenchyma. Not all subjects had abnormal vasculature due to prior surgery. However, when considering all subjects, visualization of abnormal vasculature was moderately or clearly visible in 23% of subjects when using1mg/kg, significantly less than 3mg/kg (42.7%, P = 0.0012) and 7mg/kg (43.9%, P = 0.0007). Conclusions: 3mg/kg ferumoxytol allows adequate visualization of normal and abnormal vasculature with acceptable degree of blooming artifact. Visualization of tumor vasculature may help targeting the most malignant area for surgery/radiotherapy and may help differentiating tumor progression from pseudoprogression. Clinical trial information: NCT00659776, NCT02359097.
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Suzuki, Hiroki. „Numerical visualisation on the impact of setting convective velocity of outflow boundary on a parallel grid-generated flow“. Journal of Physics: Conference Series 2369, Nr. 1 (01.11.2022): 012021. http://dx.doi.org/10.1088/1742-6596/2369/1/012021.
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This study approaches a widely used convective outflow condition for analysing turbulent flow fields with a freestream to clarify effects of the convection velocity setting. Previous studies have often used a local velocity at the outflow boundary. This study uses the setting of the outflow condition described in the previous Orlanski’s study. In this study, a two-dimensional flow induced by a parallel grid is analysed. The governing equations are spatially discretised by a second-order central difference method and integrated in the time domain using the fourth-order Runge-Kutta method. We can observe wavy profiles near the outflow boundary that vary in the streamwise direction. These wavy profiles are more evident when the local velocity is used as the convective velocity. The effect of the setting outflow velocity on the turbulence structure characterised using the second invariant of the velocity gradient tensor is also investigated.
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Burdett, N. G., D. K. Menon, T. A. Carpenter, J. G. Jones und L. D. Hall. „Visualisation of changes in regional cerebral blood flow (rCBF) produced by ketamine using long TE gradient-echo sequences: Preliminary results“. Magnetic Resonance Imaging 13, Nr. 4 (Januar 1995): 549–53. http://dx.doi.org/10.1016/0730-725x(95)00010-e.
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Barovik, Dmitry V., und Valery B. Taranchuk. „Tools for the analysis and visualisation of distributions and vector fields in surface forest fires modelling“. Journal of the Belarusian State University. Mathematics and Informatics, Nr. 2 (20.07.2022): 82–93. http://dx.doi.org/10.33581/2520-6508-2022-2-82-93.
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The problem of computer modelling of the spread of surface forest fires in a two-dimensional formulation is herein considered. We describe the initial-boundary value problem in the form of a system of partial differential equations in the accepted approximation of the corresponding physical and chemical processes with refinements of the mutually agreed defining functions and the coefficients included in the equations. The Wolfram Mathematica computer algebra system is used as a platform for developing the computer model, performing calculations, and creating a database with the outcomes of computations. The results of numerical experiments investigating possible scenarios of how a fire zone spreads in different directions and its behaviour near the fuelbreaks are presented. Several qualitative features of the structure, the evolution of the temperature front, and the vector fields of the oxygen concentration gradient over the forest area are identified and illustrated with multidimensional graphics in the presence of areas of the low content of combustible materials of various shapes and sizes, including the demonstration of the influence of the equilibrium wind speed in the forest canopy. Possible variants of the fire front movement in the direction of the wind velocity and against it are identified and explained using representative examples.
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Warren, Aaron E. L., Linda J. Dalic, Wesley Thevathasan, Annie Roten, Kristian J. Bulluss und John Archer. „Targeting the centromedian thalamic nucleus for deep brain stimulation“. Journal of Neurology, Neurosurgery & Psychiatry 91, Nr. 4 (24.01.2020): 339–49. http://dx.doi.org/10.1136/jnnp-2019-322030.
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ObjectivesDeep brain stimulation (DBS) of the centromedian thalamic nucleus (CM) is an emerging treatment for multiple brain diseases, including the drug-resistant epilepsy Lennox-Gastaut syndrome (LGS). We aimed to improve neurosurgical targeting of the CM by: (1) developing a structural MRI approach for CM visualisation, (2) identifying the CM’s neurophysiological characteristics using microelectrode recordings (MERs) and (3) mapping connectivity from CM-DBS sites using functional MRI (fMRI).Methods19 patients with LGS (mean age=28 years) underwent presurgical 3T MRI using magnetisation-prepared 2 rapid acquisition gradient-echoes (MP2RAGE) and fMRI sequences; 16 patients proceeded to bilateral CM-DBS implantation and intraoperative thalamic MERs. CM visualisation was achieved by highlighting intrathalamic borders on MP2RAGE using Sobel edge detection. Mixed-effects analysis compared two MER features (spike firing rate and background noise) between ventrolateral, CM and parafasicular nuclei. Resting-state fMRI connectivity was assessed using implanted CM-DBS electrode positions as regions of interest.ResultsThe CM appeared as a hyperintense region bordering the comparatively hypointense pulvinar, mediodorsal and parafasicular nuclei. At the group level, reduced spike firing and background noise distinguished CM from the ventrolateral nucleus; however, these trends were not found in 20%–25% of individual MER trajectories. Areas of fMRI connectivity included basal ganglia, brainstem, cerebellum, sensorimotor/premotor and limbic cortex.ConclusionsIn the largest clinical trial of DBS undertaken in patients with LGS to date, we show that accurate targeting of the CM is achievable using 3T MP2RAGE MRI. Intraoperative MERs may provide additional localising features in some cases; however, their utility is limited by interpatient variability. Therapeutic effects of CM-DBS may be mediated via connectivity with brain networks that support diverse arousal, cognitive and sensorimotor processes.
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Tamadon, Abbas, Dirk J. Pons, Don Clucas und Kamil Sued. „Texture Evolution in AA6082-T6 BFSW Welds: Optical Microscopy and EBSD Characterisation“. Materials 12, Nr. 19 (01.10.2019): 3215. http://dx.doi.org/10.3390/ma12193215.
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One of the difficulties with bobbin friction stir welding (BFSW) has been the visualisation of microstructure, particularly grain boundaries, and this is especially problematic for materials with fine grain structure, such as AA6082-T6 aluminium as here. Welds of this material were examined using optical microscopy (OM) and electron backscatter diffraction (EBSD). Results show that the grain structures that form depend on a complex set of factors. The motion of the pin and shoulder features transports material around the weld, which induces shear. The shear deformation around the pin is non-uniform with a thermal and strain gradient across the weld, and hence the dynamic recrystallisation (DRX) processes are also variable, giving a range of observed polycrystalline and grain boundary structures. Partial DRX was observed at both hourglass boundaries, and full DRX at mid-stirring zone. The grain boundary mapping showed the formation of low-angle grain boundaries (LAGBs) at regions of high shear as a consequence of thermomechanical nature of the process.
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Newling, B., S. J. Gibbs, J. A. Derbyshire, D. Xing, L. D. Hall, D. E. Haycock, W. J. Frith und S. Ablett. „Comparisons of Magnetic Resonance Imaging Velocimetry With Computational Fluid Dynamics“. Journal of Fluids Engineering 119, Nr. 1 (01.03.1997): 103–9. http://dx.doi.org/10.1115/1.2819094.
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The flow of Newtonian liquids through a pipe system comprising of a series of abrupt expansions and contractions has been studied using several magnetic resonance imaging (MRI) techniques, and also by computational fluid dynamics. Agreement between those results validates the assumptions inherent to the computational calculation and gives confidence to extend the work to more complex geometries and more complex fluids, wherein the advantages of MRI (utility in opaque fluids and noninvasiveness) are unique. The fluid in the expansion-contraction system exhibits a broad distribution of velocities and, therefore, presents peculiar challenges to the measurement technique. The MRI protocols employed were a two-dimensional tagging technique, for rapid flow field visualisation, and three-dimensional echo-planar and gradient-echo techniques, for flow field quantification (velocimetry). The Computational work was performed using the FIDAP package to solve the Navier-Stokes equations. The particular choice of parameters for both MRI and computational fluid dynamics, which affect the results and their agreement, have been addressed.
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Liddle, S. C., und N. J. Wood. „Investigation into clustering of synthetic jet actuators for flow separation control applications“. Aeronautical Journal 109, Nr. 1091 (Januar 2005): 35–44. http://dx.doi.org/10.1017/s0001924000000518.
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Abstract An investigation into the behaviour of clustered synthetic jet Actuators for flow-control applications is described. Experiments have been undertaken with two small-scale synthetic jet actuators in a zero-pressure gradient boundary-layer, in order to investigate the effect of configuration yaw angle and relative input signal phase. Oil-flow visualisation and hotwire anemometry techniques were used, demonstrating that changes in the downstream flow structure could be observed. Compared to a streamwise configuration, in which a symmetrical counter-rotating vortex pair was produced by the synthetic jet-boundary-layer interaction, a broader asymmetric interaction was produced in a 15° yaw configuration. Streamwise velocity contour plots, illustrating the development of the interaction downstream, over four phase angles, were presented. Significant differences in the PSD analyses of downstream streamwise velocity time histories were found, suggesting that input signal phase could influence the stability and hence effectiveness of flow structures used in flow-control applications.
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Eshghi, S. h., M. Jafarpour, A. Darvizeh, S. N. Gorb und H. Rajabi. „A simple, high-resolution, non-destructive method for determining the spatial gradient of the elastic modulus of insect cuticle“. Journal of The Royal Society Interface 15, Nr. 145 (August 2018): 20180312. http://dx.doi.org/10.1098/rsif.2018.0312.
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Nature has evolved structures with high load-carrying capacity and long-term durability. The principles underlying the functionality of such structures, if studied systematically, can inspire the design of more efficient engineering systems. An important step in this process is to characterize the material properties of the structure under investigation. However, direct mechanical measurements on small complex-shaped biological samples involve numerous technical challenges. To overcome these challenges, we developed a method for estimation of the elastic modulus of insect cuticle, the second most abundant biological composite in nature, through simple light microscopy. In brief, we established a quantitative link between the autofluorescence of different constituent materials of insect cuticle, and the resulting mechanical properties. This approach was verified using data on cuticular structures of three different insect species. The method presented in this study allows three-dimensional visualisation of the elastic modulus, which is impossible with any other available technique. This is especially important for precise finite-element modelling of cuticle, which is known to have spatially graded properties. Considering the simplicity, ease of implementation and high-resolution of the results, our method is a crucial step towards a better understanding of material–function relationships in insect cuticle, and can potentially be adapted for other graded biological materials.
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Alzubaidi, Laith, Asma Salhi, Mohammed A.Fadhel, Jinshuai Bai, Freek Hollman, Kristine Italia, Roberto Pareyon et al. „Trustworthy deep learning framework for the detection of abnormalities in X-ray shoulder images“. PLOS ONE 19, Nr. 3 (11.03.2024): e0299545. http://dx.doi.org/10.1371/journal.pone.0299545.
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Musculoskeletal conditions affect an estimated 1.7 billion people worldwide, causing intense pain and disability. These conditions lead to 30 million emergency room visits yearly, and the numbers are only increasing. However, diagnosing musculoskeletal issues can be challenging, especially in emergencies where quick decisions are necessary. Deep learning (DL) has shown promise in various medical applications. However, previous methods had poor performance and a lack of transparency in detecting shoulder abnormalities on X-ray images due to a lack of training data and better representation of features. This often resulted in overfitting, poor generalisation, and potential bias in decision-making. To address these issues, a new trustworthy DL framework has been proposed to detect shoulder abnormalities (such as fractures, deformities, and arthritis) using X-ray images. The framework consists of two parts: same-domain transfer learning (TL) to mitigate imageNet mismatch and feature fusion to reduce error rates and improve trust in the final result. Same-domain TL involves training pre-trained models on a large number of labelled X-ray images from various body parts and fine-tuning them on the target dataset of shoulder X-ray images. Feature fusion combines the extracted features with seven DL models to train several ML classifiers. The proposed framework achieved an excellent accuracy rate of 99.2%, F1Score of 99.2%, and Cohen’s kappa of 98.5%. Furthermore, the accuracy of the results was validated using three visualisation tools, including gradient-based class activation heat map (Grad CAM), activation visualisation, and locally interpretable model-independent explanations (LIME). The proposed framework outperformed previous DL methods and three orthopaedic surgeons invited to classify the test set, who obtained an average accuracy of 79.1%. The proposed framework has proven effective and robust, improving generalisation and increasing trust in the final results.
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Culafic, Djordje, Vladimir Djukic und Rada Jesic. „The significance of hepatopulmonary syndrome in liver transplantation“. Acta chirurgica Iugoslavica 51, Nr. 3 (2004): 67–71. http://dx.doi.org/10.2298/aci0403067c.
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The objective of the study is to determine the diagnostic role of pulmonary functional tests and perfusion pulmonary scintigraphy for quantifying the oxygenation and vascular abnormality in patients with liver cirrhosis. The prospective study included 70 patients with liver cirrhosis. Arterial blood gases analysis were performed in both supine and sitting positions while inhaling room air, and 15 minutes after exposure of hyperoxic mixture. Perfusion pulmonary scintigraphy using albumin macroagregate labelled with radioactive technetium (99mTc- MAA) was performed for the visualisation of intrapulmonary vascular dilatation. The diagnosis of hepatopulmonary syndrome was made in 10 (14.3%) patients. The patients with hepatopulmonary syndrome had severe hypoxemia (Pa,O2 7.41 +1.81 kPa), and poor response to 100% oxygen inhalation (Pa,O2 21.07 + 14.41 kPa) and higher alveolo-arterial gradient (5.73 + 2.65 kPa). Radioisotope marker 99mTc-MAA skipped intrapulmonary circulation in all patients with HPS and in no one without pulmonary vascular dilatations. The combined approach of 100% inspired oxygen and perfusion pulmonary scintigraphy may identify early oxygenation disorders and alter the priority for liver transplantation, especially in view of potential syndrome resolution.
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Partovi, Aschwanden, Staub, Rasmus, Zipp, Rengier, Jacobi, Hügli und Bilecen. „Gadofosveset enhanced MR phlebography for detecting pelvic and deep vein leg thrombosis“. Vasa 40, Nr. 4 (01.07.2011): 315–19. http://dx.doi.org/10.1024/0301-1526/a000121.
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Background: Deep venous thrombosis is mainly diagnosed by ultrasound today. In some instances diagnosis is challenging and magnetic resonance angiography could be an attractive alternative. Gadofosveset is a blood pool contrast agent with some favourable properties for this purpose. Patients and methods: We investigated eight patients with proven deep venous thrombosis by Gadofosveset enhanced MR phlebography. We performed a 3D gradient-echo sequence with an overall measurement time of 9 minutes and 6 seconds. One minute after injection of Gadofosveset in a concentration of 0.12 ml/kg body weight images were acquired. Thrombi were visualised by their lack of luminal contrast filling. Results: Thrombi were visualised in all patients. In one patient with extended thrombosis a previously undiagnosed ovarian adenocarcinoma was detected additionally. Conclusions: Deep venous thromboses in lower extremities can be visualised reliably by performing MR phlebography with blood pool contrast agent Gadofosveset. Visualisation of the complete venous system is feasible. This investigation method may be performed in patients difficult to investigate with ultrasound or may be used for planning interventional procedures.
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Suprenand, P. M., D. L. Jones und J. J. Torres. „Distribution of gymnosomatous pteropods in western Antarctic Peninsula shelf waters: influences of Southern Ocean water masses“. Polar Record 51, Nr. 1 (11.11.2013): 58–71. http://dx.doi.org/10.1017/s003224741300065x.
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ABSTRACTDistributions of gymnosomatous pteropods,Spongiobranchaea australisandClione antarctica, were determined at six sites along a latitudinal gradient in western Antarctica Peninsula shelf waters using vertically stratified trawls. Hydrographic data were collected at the same sites with conductivity-temperature-depth casts, and correlations of explanatory variables to gymnosome distributions were determined using statistical analyses performed in Matlab, a high level programming software to conduct numerical computation and visualisation. Explanatory variables included sampling site, latitude, longitude and depth, seawater temperature, salinity and density, Southern Ocean Antarctic Surface Water, Winter Water, Upper Circumpolar Deep Water and warm transitional waters, as well as oceanographic remote sensing data for coloured dissolved organic matter, chlorophyllaconcentration, normalised fluorescence line height, nighttime sea surface temperature, photosynthetically active radiation, particulate inorganic carbon, particulate organic carbon, daytime sea surface temperature and daily sea ice concentration. Hydrographic data revealed that warmer water masses were prevalent along the western Antarctic Peninsula, and the distributions of both gymnosome species were primarily influenced by water masses, temperature, sampling site and latitude. As a consequence, distributional shifts of gymnosomes are predicted in response to the current warming trends.
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M T, Olowokere, Amadou Hassane, Alonge M. A und Adekola E. Ajibade. „Hydrocarbon prospectively determination of “eagle field”, coastal swamp ii Niger delta.“ International Journal of Advanced Geosciences 7, Nr. 1 (11.05.2019): 52. http://dx.doi.org/10.14419/ijag.v7i1.11471.
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Seismic and well log data were collected from onshore depobelt of Nigeria with a total of 1000 seismic lines and 3 wells. The main objective of the study was to determine hydrocarbon prospectivity and reserve estimates of the field. The evaluation centred on seismic interpretation and 3D visualisation (DHI detection) of the “Ejanla Field” 3D in total, Four horizons have been interpreted regionally for correlation purposes and three as prospect specific horizons. Four prospects and some, more speculative leads were identified in the area of which most are conventional three way dip/fault closures and some hanging wall closures. The potential for stratigraphic trapping was also recognized. The study showed that the small closure areas and limited hydrocarbon column lengths affected the number of prospects and at the shallow levels.The main risk to oil prospectivity in the area as revelled by the data interpretation is gas which may have resulted from the observed higher geothermal gradient in the deeper depth. Reservoir development and retention (overpressure) for prospects and leads in the deeper and more distal sedimentological settings form additional risks.
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Juchems, Markus S., Deniz Uyak, Andrea S. Ernst und Hans-Juergen Brambs. „Monitoring Gastric Filling, Satiety and Gastric Emptying in a Patient with Gastric Balloon Using Functional Magnetic Resonance Imaging–-A Feasibility Report“. Clinical Medicine: Case Reports 1 (Januar 2008): CCRep.S781. http://dx.doi.org/10.4137/ccrep.s781.
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Backround Intragastric balloons are used for short term weight loss therapy in obese. It is possible to monitor the ballon with sonography, however this method is sometimes insufficient in obese patients. Therefore MRI seems to be a potential therapy-monitoring option. Purpose In this feasibility report we want to demonstrate the potential use of functional MRI in monitoring gastric filling, patient satiation and gastric emptying in a obese patient who previously received intragastric balloon placement. Material and methods We selected one patient (male, 178 cm, 127 kg, BMI = 40,5 kg/m2) who recently received a gastric balloon and visualized gastric motility in presence of the gastric balloon before and after food intake. Fast cross-sectional images in one breathhold spin echo or gradient echo sequences were aquired. Real-time gastric motion was performed with cine mode. Results MRI offers perfect visualisation of gastric balloons in obese patients. Gastric filling and emptying can be monitored in correlation to patient satiety sensation. MRI can visualize the gastric balloon with degree of filling and possible leakages. Cine mode sequences demonstrate gastric motility and gastric wall peristalsis. Conclusion MR is a valuable imaging alternative for patients with intragastric balloons
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MacKay, J., A. Jucaite, Z. Cselényi, P. Johnström, K. Dahl, M. Schou, P. Stenkrona et al. „P014 First-time-in-human visualisation of CCR9 expression in the gut by positron emission tomography“. Journal of Crohn's and Colitis 18, Supplement_1 (01.01.2024): i263. http://dx.doi.org/10.1093/ecco-jcc/jjad212.0144.
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Abstract Background CCR9/CCL25 is the key axis for recruiting lymphocytes to the small intestine and represents a potential treatment target in Crohn’s disease (CD). AZD7798 is a first-in-class monoclonal antibody for CD that depletes CCR9+ lymphocytes. Monitoring CCR9+ cell depletion and repletion in the blood is straightforward, but difficult in the primary tissues of interest (small bowel, mesenteric lymph nodes) which require invasive procedures to access. For AZD7798, an understanding of pharmacodynamics in gut is crucial to guide further clinical development. To address this need, we have developed a CCR9-specific PET tracer based on the small molecule CCR9 antagonist vercirnon. Methods Specific binding of [3H]vercirnon was assessed in-vitro using autoradiography. Specific binding and dosimetry of [11C]vercirnon was assessed in-vivo in cynomolgus monkeys. Subsequently, a first-time-in-human study (NCT05818514) was performed in healthy volunteers to assess the biodistribution, binding to CCR9 in abdominal regions of interest, and safety of [11C]vercirnon, administered intravenously at microdoses (<10μg). Two PET-CT examinations were performed 14 days apart to assess reproducibility. Results In-vitro specific binding of [3H]vercirnon to CCR9 was confirmed in human thymus sections and CCR9-expressing cell pellets. In-vivo specific binding of [11C]vercirnon to CCR9 was putatively demonstrated in the gut of non-human primates (NHPs) in pre-treatment/displacement studies with excess unlabelled vercirnon (20mg/kg). 8 healthy volunteers (5 male) were enrolled in the FTIH study. Detectable intestinal uptake of [11C]vercirnon was demonstrated in all participants (Figure 1) with mean±SD standardised uptake value ratio (SUVR) 1.4±0.6 (reference abdominal aorta), and a proximal to distal gradient (SUVR jejunum 1.8±0.7/ileum 0.9±0.4/colon 0.6±0.2) consistent with CCR9 gene expression data. Test-retest variability of intestinal uptake was 9.6% (intraclass correlation coefficient 0.96), in line with values for other clinically useful PET tracers. Mean±SD injected radioactivity per PET examination was 351±105 MBq, corresponding to a radiation exposure of 1.4 mSv. This low radiation exposure (c.f. conventional FDG PET ~9 mSv) allows multiple PET examinations per participant. Administration of [11C]vercirnon was well-tolerated with no serious adverse events. Conclusion We have developed a CCR9-specific PET tracer which potentially enables repeatable quantification of CCR9 expression in the gut. Ongoing studies will assess the effects of AZD7798 on CCR9+ cell depletion/repletion in the gut, providing critical data to support the clinical development programme.
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Oehme, Felix, Janick Suhr, Nicholas Balaresque, Daniel Gleichauf, Michael Sorg und Andreas Fischer. „Thermographic Stall Detection by Model-Inspired Evaluation of the Dynamic Temperature Behaviour“. Applied Sciences 11, Nr. 18 (11.09.2021): 8442. http://dx.doi.org/10.3390/app11188442.
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Model-inspired signal processing approaches with an enhanced detectability of flow separation on thermographic images are presented. Flow separation causes performance loss, structural loads and increasing acoustic emissions on wind turbine rotor blades. However, due to the low thermal contrast between turbulent and separated flow regions, the non-invasive thermographic visualisation of flow separation is currently only possible for wind tunnel measurements, which are characterised by a high thermal contrast and a small measuring distance. The state-of-the-art signal processing approaches evaluate the surface temperature fluctuation of thermographic image series. However, understanding of the signal measurement chain with a distinct consideration of the influences on the dynamic surface temperature is incomplete. Therefore, designing model-inspired signal processing approaches which provide a high interpretability and a maximum contrast is an open task. The proposed signal processing approaches evaluate the surface response selectively, by using the amplitude information of the surface temperature response to an oscillating input signal or gradient-based for a transient input signal. The approaches are applied to wind tunnel measurements on a rotor blade profile at a near thermodynamic steady state and a transient thermodynamic behaviour at Reynolds numbers that are representative for operational wind turbines. The gradient-based evaluation shows an improved contrast for the detection of flow separation, but is only applicable to profiles with transient thermodynamic behaviour. The amplitude evaluation provides a high degree of interpretability of the processed images based on flow-dependent features and enables for an unambiguous identification of flow separation by a global amplitude minimum close to the separation point. Additionally, an increased spatial resolution for surface modifications is shown, while the contrast between flow regions is significantly decreased. Hence, the proposed approaches allow for an improved identifiability of flow separation with regard to future applications on wind turbines in operation.
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Huneault, Justin, David Plant und Andrew J. Higgins. „Rotational stabilisation of the Rayleigh–Taylor instability at the inner surface of an imploding liquid shell“. Journal of Fluid Mechanics 873 (25.06.2019): 531–67. http://dx.doi.org/10.1017/jfm.2019.346.
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A number of applications utilise the energy focussing potential of imploding shells to dynamically compress matter or magnetic fields, including magnetised target fusion schemes in which a plasma is compressed by the collapse of a liquid metal surface. This paper examines the effect of fluid rotation on the Rayleigh–Taylor (RT) driven growth of perturbations at the inner surface of an imploding cylindrical liquid shell which compresses a gas-filled cavity. The shell was formed by rotating water such that it was in solid body rotation prior to the piston-driven implosion, which was propelled by a modest external gas pressure. The fast rise in pressure in the gas-filled cavity at the point of maximum convergence results in an RT unstable configuration where the cavity surface accelerates in the direction of the density gradient at the gas–liquid interface. The experimental arrangement allowed for visualisation of the cavity surface during the implosion using high-speed videography, while offering the possibility to provide geometrically similar implosions over a wide range of initial angular velocities such that the effect of rotation on the interface stability could be quantified. A model developed for the growth of perturbations on the inner surface of a rotating shell indicated that the RT instability may be suppressed by rotating the liquid shell at a sufficient angular velocity so that the net surface acceleration remains opposite to the interface density gradient throughout the implosion. Rotational stabilisation of high-mode-number perturbation growth was examined by collapsing nominally smooth cavities and demonstrating the suppression of small spray-like perturbations that otherwise appear on RT unstable cavity surfaces. Experiments observing the evolution of low-mode-number perturbations, prescribed using a mode-6 obstacle plate, showed that the RT-driven growth was suppressed by rotation, while geometric growth remained present along with significant nonlinear distortion of the perturbations near final convergence.
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Lemenkova, Polina. „Variations in the bathymetry and bottom morphology of the Izu-Bonin Trench modelled by GMT“. Bulletin of Geography. Physical Geography Series 18, Nr. 1 (23.06.2020): 41–60. http://dx.doi.org/10.2478/bgeo-2020-0004.
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AbstractCartographic visualisation is a central concept in geoinformatics, and Generic Mapping Tools (GMT) functionality provides a variety of modules for effective mapping. However, due to its specific scripting approach, there is not enough reported experience of GMT mapping, comparing to traditional GIS. This contribution introduces steps that can be taken to perform cartographic mapping and modelling using GMT. Geographically, this paper investigates the Izu-Bonin Trench in the Pacific Ocean. The aim was to compare its geomorphology in two segments, and each was modelled by a series of profiles. The comparative analysis shows that the southern segment is deeper and is a more precisely V-shaped form with a steeper gradient slope. The northern part has an asymmetric slope with submarine terraces to the west and a straight shape to the east. The northern profile is based on 407 samples (13.5%) at depths of −5,600 to −5,800 m, followed by 304 samples at −5,800 to −6,000 m (10%). The southern histogram has a bimodal distribution with two peaks: 523 samples (20%) with depths of −5,800 to −6,000 m. The second peak (10%) is on the Bonin Ridge. The GMT proved to be an effective instrument for marine geological mapping, 3D and 2D modelling, statistical analysis and graphical plotting.
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Drejer, J., H. S. Thomsen und J. Tanttu. „Low-Field MR Imaging of the Spine“. Acta Radiologica 36, Nr. 4-6 (Juli 1995): 505–9. http://dx.doi.org/10.1177/028418519503600438.
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Purpose: To evaluate a new steady-state sequence in the delineation of the various structures in the spine at low-field MR imaging with a very high homogeneity of the main field. Methods: 49 patients underwent 53 examinations with both a traditional T1-weighted gradient-echo (PS) sequence and a new completely balanced steady-state 3-D (CBASS3D) sequence; 20 examinations included the cervical spine, 8 the thoracic spine and 25 the lumbar spine. All 106 examinations were reviewed twice regarding visibility of selected structures in the spinal region and diagnostic usefulness. Results: The CBASS3D sequence delineated the medulla, nerve roots, CSF, the intervertebral discs and the posterior longitudinal ligament significantly better than the PS sequence. Disc hernia was also better visualised (p<0.01). There were significantly more artefacts on images obtained with the CBASS3D sequence, but they were usually outside the region of interest and occurred less frequently over time due to increased experience of the staff. Both reviewers found the diagnostic usefulness of CBASS3D to be superior compared to that of PS and excellent for diagnostic purposes. Conclusion: The CBASS3D sequence is a considerable improvement in the visualisation of degenerative changes of the spine at low-field MR imaging.
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Saravanan, R., S. L. N. Desikan und T. M. Muruganandam. „Effect of back pressure and freestream dynamic pressure on a typical Ramjet engine duct under realistic supersonic inlet condition“. Aeronautical Journal 122, Nr. 1247 (10.11.2017): 83–103. http://dx.doi.org/10.1017/aer.2017.115.
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ABSTRACTThe present study investigates the behaviour of the shock train in a typical Ramjet engine under the influence of shock and expansion waves at the entry of a low aspect ratio (1:0.75) rectangular duct/isolator at supersonic Mach number (M = 1.7). The start/unstart characteristics are investigated through steady/unsteady pressure measurements under different back and dynamic pressures while the shock train dynamics are captured through instantaneous Schlieren flow visualisation. Two parameters, namely pressure recovery and the pressure gradient, is derived to assess the duct/isolator performance. For a given back pressure, with maximum blockage (9% above nominal), the duct/isolator flow is established when the dynamic pressure is increased by 23.5%. The unsteady pressure measurements indicate different scales of eddies above 80 Hz (with and without flap deflection). Under the no flap deflection (no back pressure) condition, the maximum fluctuating pressure component is 0.01% and 0.1% of the stagnation pressure at X/L = 0.03 (close to the entry of the duct) and X/L = 0.53 (middle of the duct), respectively. Once the flap is deflected (δ = 8°), decay in eddies by one order is noticed. Further increase in back pressure (δ ≥ 11°) leads the flow to unstart where eddies are observed to be disappeared.
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Saul, A. J., und D. R. Ellis. „Sediment Deposition in Storage Tanks“. Water Science and Technology 25, Nr. 8 (01.04.1992): 189–98. http://dx.doi.org/10.2166/wst.1992.0193.
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The use of storage tanks in sewerage systems has increased in recent years. The primary functions of such tanks are to attenuate flow and to retain pollutants within the sewer system. The size of the required storage volume is dependent on the purpose for which the tank is to be used but the end product of any design analysis is the definition of fixed volume of storage which has to be included as part of the sewerage system. The main problem is to provide storage and effective separation of gross and suspended solids without incurring poor self cleansing and associated high maintenance costs. The work outlined in this paper involved the development of a laboratory computer controlled monitoring system for the purpose of flow visualisation and for the comparative assessment of the sediment deposition and removal performance of different geometric configurations of storage tank. These systems used sophisticated control procedures and the latter had the facility to generate a flow hydrograph of any shape and duration and to superimpose on this hydrograph a pollutograph of synthetic sediment, in this case crushed olive stone wood flour. Particular attention was focused on the optimum length to breadth ratio for a given storage volume, the configuration of the chamber floor - number, shape and gradient of dry weather flow channels and benching (gradient; the type of roof support and the effect of multiple storms on the redistribution of deposited sediment. The results of the work illustrated that very complex flow patterns were established within the storage tanks as the flow hydrograph was discharged through the system and that these flow patterns governed the sediment settlement, re-entrainment and transport processes in the tank. The velocity distribution within each chamber was a function of tank geometry, the shape, volume, and duration of the inflow hydrograph and the throughflow setting. The paper is concluded by a series of recommendations to aid the design of storage tanks.
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Nham, Benjamin, und Simon Hawke. „034 The susceptibility vessel sign: a clinical-radiological case of propagating left MCA thrombus with resolving neurological deficits“. Journal of Neurology, Neurosurgery & Psychiatry 89, Nr. 6 (24.05.2018): A14.2—A14. http://dx.doi.org/10.1136/jnnp-2018-anzan.33.
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IntroductionThe susceptibility vessel sign (SVS) is a radiological sign on the SWI sequence of MRI that can predict cardioembolic source and increased recanalisation rates in stroke.1 We present a case of an 86 year old female with resolving neurological deficits from a propagating left MCA thrombus with positive SVS on imaging.CaseAn 86 year old female presented with sudden onset right sided weakness and expressive aphasia in the context of new atrial fibrillation. Her NIHSS was 4. Initial CT angiogram showed complete occlusion of the proximal M1 segment of the left middle cerebral artery. She was within the thrombolysis window but her deficits largely resolved (NHISS 0) before thrombolysis could be administered. A repeat CT angiogram one hour after the first scan showed complete resolution of the MCA occlusion. An MRI brain showed curvilinear gradient signal hypointensity in the distal left M2 segment of the MCA (positive SVS) with a small area of infarction and restricted diffusion. She was discharged on apixaban without neurological deficit. This is a unique case of a stroke patient, with proximal large vessel occlusion, presenting with neurological deficits that self-resolved within minutes without thrombolysis or thrombectomy. There was a positive SVS on MRI. This radiological sign allows direct visualisation of the hypointense thrombo-embolus on the SWI sequence. It occurs as there is a higher level of deoxy-haemoglobin content in the thrombo-embolus and is predictive of a cardioembolic source as cardioembolic thrombi are rich in erythrocytes1.ConclusionOur case demonstrated interesting clinical-radiological-pathological correlation in cardioembolic stroke with resolving neurological deficits. The patient’s clinical improvement matched the radiological improvement and corresponded to the pathophysiological course of thrombus from embolization, propagation, occlusion, dissolution and then recanalisation. The SVS is a useful radiological sign to predict cardioembolic sources of stroke and is associated with higher vessel re-canalisation rates.Reference. Cho KH, Kim JS, Kwon SU, et al. Significance of susceptibility vessel sign on T2*-weighted gradient echo imaging for identification of stroke subtypes. Stroke2005;36:2379–2383.
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Maraschini, Alice, Emiliano Ceccarelli, Manuela Giangreco, Lorenzo Monasta, Valerio Manno, Dolores Catelan, Giorgia Stoppa et al. „Development of an Italian National Epidemiological Register on Endometriosis Based on Administrative Data“. Journal of Clinical Medicine 13, Nr. 11 (24.05.2024): 3087. http://dx.doi.org/10.3390/jcm13113087.
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Background/Objectives: Endometriosis is a female chronic inflammatory disease in which endometrial tissue develops outside the uterine cavity. It is a complex pathology, which significantly contributes to morbidity in premenopausal women, leading to chronic pain, infertility, and subfertility negatively impacting physical and emotional well-being and the overall quality of life. The public health burden of endometriosis remains elusive and challenging to determine, and this uncertainty can lead to inadequate healthcare services and treatments. The objective was to estimate the incidence and prevalence of endometriosis in Italy using the hospital discharge records database via a population-based retrospective study, nationwide between 2011 and 2020. Methods: From the National Hospital Discharge Database, we selected all admissions with a diagnosis of endometriosis (ICD-9-CM, codes 617.x), supported by the presence of a procedure code of laparoscopy or any other surgical procedure allowing for direct visualisation of the lesions. The main outcomes measured: incidence and prevalence of endometriosis were estimated for the entire 2011–2020 period and by individual year, analysing the time trend and variability in different geographical areas of Italy. Results: There were a total of 134,667,646 women aged 15–50 years with one or more hospitalisations for endometriosis in all Italian hospitals. The incidence of endometriosis in Italy during this period was 0.839 per 1000 women (CI95% 0.834–0.844), exhibiting a statistically significant decreasing trend over the years. A discernible north–south gradient was observed, with higher rates documented in the northern regions. The prevalence rate stood at 14.0 per 1000 during the same period, and a similar north–south geographical gradient was identifiable in the prevalence rates as well. Conclusions: The utilization of national-level hospital data enables the generation of incidence and prevalence data for endometriosis without variations in methods and definitions, facilitating the evaluation of temporal trends and regional comparisons. Understanding and quantifying this phenomenon is essential for appropriate healthcare planning in various Italian regions.
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Abitbol, Elie, Alexandra Miere, Jean-Baptiste Excoffier, Carl-Joe Mehanna, Francesca Amoroso, Samuel Kerr, Matthieu Ortala und Eric H. Souied. „Deep learning-based classification of retinal vascular diseases using ultra-widefield colour fundus photographs“. BMJ Open Ophthalmology 7, Nr. 1 (Februar 2022): e000924. http://dx.doi.org/10.1136/bmjophth-2021-000924.
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ObjectiveTo assess the ability of a deep learning model to distinguish between diabetic retinopathy (DR), sickle cell retinopathy (SCR), retinal vein occlusions (RVOs) and healthy eyes using ultra-widefield colour fundus photography (UWF-CFP).Methods and AnalysisIn this retrospective study, UWF-CFP images of patients with retinal vascular disease (DR, RVO, and SCR) and healthy controls were included. The images were used to train a multilayer deep convolutional neural network to differentiate on UWF-CFP between different vascular diseases and healthy controls. A total of 224 UWF-CFP images were included, of which 169 images were of retinal vascular diseases and 55 were healthy controls. A cross-validation technique was used to ensure that every image from the dataset was tested once. Established augmentation techniques were applied to enhance performances, along with an Adam optimiser for training. The visualisation method was integrated gradient visualisation.ResultsThe best performance of the model was obtained using 10 epochs, with an overall accuracy of 88.4%. For DR, the area under the receiver operating characteristics (ROC) curve (AUC) was 90.5% and the accuracy was 85.2%. For RVO, the AUC was 91.2% and the accuracy 88.4%. For SCR, the AUC was 96.7% and the accuracy 93.8%. For healthy controls, the ROC was 88.5% with an accuracy that reached 86.2%.ConclusionDeep learning algorithms can classify several retinal vascular diseases on UWF-CPF with good accuracy. This technology may be a useful tool for telemedicine and areas with a shortage of ophthalmic care.
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Thomas, M., R. W. Fitzpatrick und G. S. Heinson. „An expert system to predict intricate saline - sodic subsoil patterns in upland South Australia“. Soil Research 47, Nr. 6 (2009): 602. http://dx.doi.org/10.1071/sr08244.
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Digital soil mapping (DSM) offers apparent benefits over more labour-intensive and costly traditional soil survey. Large cartographic scale (e.g. 1 : 10 000 scale) soil maps are rare in Australia, especially in agricultural areas where they are needed to support detailed land evaluation and targeted land management decisions. We describe a DSM expert system using environmental correlation that applies a priori knowledge from a key area (128 ha) soil–landscape with a regionally repeating toposequence to predict the distribution of saline–sodic subsoil patterns in the surrounding upland farming region (2275 ha) in South Australia. Our predictive framework comprises interrelated and iterative steps, including: (i) consolidating a priori knowledge of the key area soil–landscape; (ii) refining existing mentally held and graphic soil–landscape models; (iii) selecting suitable environmental covariates compatible with geographic information systems (GIS) by interrogation via 3D visualisation using a GIS; (iv) transforming the existing soil–landscape models to a computer model; (v) applying the computer model to the environmental variables using the expert system; (vi) performing the predictive mapping; and (vii) validation. The environmental covariates selected include: digital terrain attributes of slope gradient, topographic wetness index and plan curvature, and airborne gamma-radiometric K%. We apply selected soil profile physiochemical data from a prior soil survey to validate mapping. Results showed that we correctly predicted the saline–sodic subsoils in 10 of 11 reference profiles in the region.
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Alammar, Zaenab, Laith Alzubaidi, Jinglan Zhang, Yuefeng Li, Waail Lafta und Yuantong Gu. „Deep Transfer Learning with Enhanced Feature Fusion for Detection of Abnormalities in X-ray Images“. Cancers 15, Nr. 15 (07.08.2023): 4007. http://dx.doi.org/10.3390/cancers15154007.
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Medical image classification poses significant challenges in real-world scenarios. One major obstacle is the scarcity of labelled training data, which hampers the performance of image-classification algorithms and generalisation. Gathering sufficient labelled data is often difficult and time-consuming in the medical domain, but deep learning (DL) has shown remarkable performance, although it typically requires a large amount of labelled data to achieve optimal results. Transfer learning (TL) has played a pivotal role in reducing the time, cost, and need for a large number of labelled images. This paper presents a novel TL approach that aims to overcome the limitations and disadvantages of TL that are characteristic of an ImageNet dataset, which belongs to a different domain. Our proposed TL approach involves training DL models on numerous medical images that are similar to the target dataset. These models were then fine-tuned using a small set of annotated medical images to leverage the knowledge gained from the pre-training phase. We specifically focused on medical X-ray imaging scenarios that involve the humerus and wrist from the musculoskeletal radiographs (MURA) dataset. Both of these tasks face significant challenges regarding accurate classification. The models trained with the proposed TL were used to extract features and were subsequently fused to train several machine learning (ML) classifiers. We combined these diverse features to represent various relevant characteristics in a comprehensive way. Through extensive evaluation, our proposed TL and feature-fusion approach using ML classifiers achieved remarkable results. For the classification of the humerus, we achieved an accuracy of 87.85%, an F1-score of 87.63%, and a Cohen’s Kappa coefficient of 75.69%. For wrist classification, our approach achieved an accuracy of 85.58%, an F1-score of 82.70%, and a Cohen’s Kappa coefficient of 70.46%. The results demonstrated that the models trained using our proposed TL approach outperformed those trained with ImageNet TL. We employed visualisation techniques to further validate these findings, including a gradient-based class activation heat map (Grad-CAM) and locally interpretable model-independent explanations (LIME). These visualisation tools provided additional evidence to support the superior accuracy of models trained with our proposed TL approach compared to those trained with ImageNet TL. Furthermore, our proposed TL approach exhibited greater robustness in various experiments compared to ImageNet TL. Importantly, the proposed TL approach and the feature-fusion technique are not limited to specific tasks. They can be applied to various medical image applications, thus extending their utility and potential impact. To demonstrate the concept of reusability, a computed tomography (CT) case was adopted. The results obtained from the proposed method showed improvements.
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Al-Dhamari, Ibraheem, Rania Helal, Olesia Morozova, Tougan Abdelaziz, Roland Jacob, Dietrich Paulus und Stephan Waldeck. „Automatic intra-subject registration and fusion of multimodal cochlea 3D clinical images“. PLOS ONE 17, Nr. 3 (02.03.2022): e0264449. http://dx.doi.org/10.1371/journal.pone.0264449.
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Background The postoperative imaging assessment of Cochlear Implant (CI) patients is imperative. The main obstacle is that Magnetic Resonance imaging (MR) is contraindicated or hindered by significant artefacts in most cases with CIs. This study describes an automatic cochlear image registration and fusion method that aims to help radiologists and surgeons to process pre-and postoperative 3D multimodal imaging studies in cochlear implant (CI) patients. Methods and findings We propose a new registration method, Automatic Cochlea Image Registration (ACIR-v3), which uses a stochastic quasi-Newton optimiser with a mutual information metric to find 3D rigid transform parameters for registration of preoperative and postoperative CI imaging. The method was tested against a clinical cochlear imaging dataset that contains 131 multimodal 3D imaging studies of 41 CI patients with preoperative and postoperative images. The preoperative images were MR, Multidetector Computed Tomography (MDCT) or Cone Beam Computed Tomography (CBCT) while the postoperative were CBCT. The average root mean squared error of ACIR-v3 method was 0.41 mm with a standard deviation of 0.39 mm. The results were evaluated quantitatively using the mean squared error of two 3D landmarks located manually by two neuroradiology experts in each image and compared to other previously known registration methods, e.g. Fast Preconditioner Stochastic Gradient Descent, in terms of accuracy and speed. Conclusions Our method, ACIR-v3, produces high resolution images in the postoperative stage and allows for visualisation of the accurate anatomical details of the MRI with the absence of significant metallic artefacts. The method is implemented as an open-source plugin for 3D Slicer tool.
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Li, Daihong, Zhili Tang, Qian Kang, Xiaoyu Zhang und Youhua Li. „Machine Learning-Based Method for Predicting Compressive Strength of Concrete“. Processes 11, Nr. 2 (27.01.2023): 390. http://dx.doi.org/10.3390/pr11020390.
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Accurate prediction of the compressive strength of concrete is of great significance to construction quality and progress. In order to understand the current research status in the concrete compressive strength prediction field, a bibliometric analysis of the relevant literature published in this field in the last decade was conducted first. The 3135 journal articles published from 2012 to 2021 in the Web of Science core database were used as the database, and the knowledge map was drawn with the help of the visualisation software CiteSpace 6.1R2 to analyse the field at the macro level in terms of spatial and temporal distribution, hotspot distribution and evolutionary trends, respectively. Afterwards, we go into the detail and divide concrete compressive strength prediction methods into two categories: traditional and machine-learning methods, and introduce the typical methods of each. In addition, a boosting-based ensemble machine-learning algorithm, namely the gradient boosting regression tree (GBRT) algorithm, is proposed for predicting the compressive strength of concrete. 1030 sets of concrete compressive strength test data were collected as the dataset, of which 60% were used to train the model, 20% to validate the model and 20% to test the trained model. The coefficient of determination (R2) of the GBRT model was 0.92, the mean square error (MSE) was 22.09 MPa, and the root mean square error (RMSE) was 4.7 MPa, which is an excellent prediction accuracy compared to prediction models constructed by other machine-learning algorithms. In addition, a five-fold cross-validation analysis was carried out, and the eight input variables were analyzed for their characteristic importance.
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Pogorelskiy, Sergey, und Imre Kocsis. „BIM and Computational Fluid Dynamics Analysis for Thermal Management Improvement in Data Centres“. Buildings 13, Nr. 10 (19.10.2023): 2636. http://dx.doi.org/10.3390/buildings13102636.
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One of the most energy-intensive facilities requiring a comprehensive and well-optimised cooling system is the data centre. Air containment across the data centre is a key thermal management and energy-saving strategy that enhances the performance of data centres. The majority of modern energy-efficient data centres use some type of air containment. The primary advantage of aisle separation and containment is the decrease in the air temperature at the server inlet by reducing the mixing of hot air with cold air. In order to ascertain the volume of literature relating to corridor insulation, we conducted a literature review. Currently, there have been numerous articles regarding the application of computational fluid dynamics (CFD) analysis, however, publications delineating the integration of building information modelling (BIM) principles for corridor separation are still limited. Research specifically targeting data centre corridor insulation is somewhat limited. As a result of this analysis, the most common methods used to isolate hot or cold aisles within a data centre were identified. To determine the most effective type of corridor insulation, the BIM family was created in Autodesk Revit. The model includes 15 telecom cabinets containing information technology (IT) equipment, eight inter-row air conditioners, and one UPS. The model was used for the CFD analysis of the air temperature in different zones of the room. Visualisation of the results using gradient temperature distributions at different levels provides a complete picture of the microclimate formation in the room and allowed the advantage of the hot aisle isolation scheme to be demonstrated.
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Bindhumol, V. R. „Proportion of Poor Visualisation of Glottis Documented Using CormackLehane Grading During Anaesthesia“. Journal of Medical Science And clinical Research 05, Nr. 06 (30.06.2017): 24005–13. http://dx.doi.org/10.18535/jmscr/v5i6.198.
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Koch, Lukas. „Post-hoc regularisation of unfolded cross-section measurements“. Journal of Instrumentation 17, Nr. 10 (01.10.2022): P10021. http://dx.doi.org/10.1088/1748-0221/17/10/p10021.
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Abstract Neutrino cross-section measurements are often presented as unfolded binned distributions in “true” variables. The ill-posedness of the unfolding problem can lead to results with strong anti-correlations and fluctuations between bins, which make comparisons to theoretical models in plots difficult. To alleviate this problem, one can introduce regularisation terms in the unfolding procedure. These suppress the anti-correlations in the result, at the cost of introducing some bias towards the expected shape of the data. This paper discusses a method using simple linear algebra, which makes it is possible to regularise any result that is presented as a central value and a covariance matrix. This “post-hoc” regularisation is generally much faster than repeating the unfolding method with different regularisation terms. The method also yields a regularisation matrix which connects the regularised to the unregularised result, and can be used to retain the full statistical power of the unregularised result when publishing a nicer looking regularised result. In addition to the regularisation method, this paper also presents some thoughts on the presentation of correlated data in general. When using the proposed method, the bias of the regularisation can be understood as a data visualisation problem rather than a statistical one. The strength of the regularisation can be chosen by minimising the difference between the implicitly uncorrelated distribution shown in the plots and the actual distribution described by the unregularised central value and covariance. Aside from minimising the difference between the shown and the actual result, additional information can be provided by showing the local log-likelihood gradient of the models shown in the plots. This adds more information about where the model is “pulled” by the data than just comparing the bin values to the data's central values.
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Chin, C., J. Philip, J. Klewicki, A. Ooi und I. Marusic. „Reynolds-number-dependent turbulent inertia and onset of log region in pipe flows“. Journal of Fluid Mechanics 757 (26.09.2014): 747–69. http://dx.doi.org/10.1017/jfm.2014.486.
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AbstractA detailed analysis of the ‘turbulent inertia’ (TI) term (the wall-normal gradient of the Reynolds shear stress,$\mathrm{d} \langle -uv\rangle /\mathrm{d} y $), in the axial mean momentum equation is presented for turbulent pipe flows at friction Reynolds numbers$\delta ^{+} \approx 500$, 1000 and 2000 using direct numerical simulation. Two different decompositions for TI are employed to further understand the mean structure of wall turbulence. In the first, the TI term is decomposed into the sum of two velocity–vorticity correlations ($\langle v \omega _z \rangle + \langle - w \omega _y \rangle $) and their co-spectra, which we interpret as an advective transport (vorticity dispersion) contribution and a change-of-scale effect (associated with the mechanism of vorticity stretching and reorientation). In the second decomposition, TI is equivalently represented as the wall-normal gradient of the Reynolds shear stress co-spectra, which serves to clarify the accelerative or decelerative effects associated with turbulent motions at different scales. The results show that the inner-normalised position,$y_m^{+}$, where the TI profile crosses zero, as well as the beginning of the logarithmic region of the wall turbulent flows (where the viscous force is leading order) move outwards in unison with increasing Reynolds number as$y_m^{+} \sim \sqrt{\delta ^{+}}$because the eddies located close to$y_m^{+}$are influenced by large-scale accelerating motions of the type$\langle - w \omega _y \rangle $related to the change-of-scale effect (due to vorticity stretching). These large-scale motions of$O(\delta ^{+})$gain a spectrum of larger length scales with increasing$\delta ^{+}$and are related to the emergence of a secondary peak in the$-uv$co-spectra. With increasing Reynolds number, the influence of the$O(\delta ^{+})$motions promotes viscosity to act over increasingly longer times, thereby increasing the$y^{+}$extent over which the mean viscous force retains leading order. Furthermore, the TI decompositions show that the$\langle v \omega _z \rangle $motions (advective transport and/or dispersion of vorticity) are the dominant mechanism in and above the log region, whereas$\langle - w \omega _y \rangle $motions (vorticity stretching and/or reorientation) are most significant below the log region. The motions associated with$\langle - w \omega _y \rangle $predominantly underlie accelerations, whereas$\langle v \omega _z \rangle $primarily contribute to decelerations. Finally, a description of the structure of wall turbulence deduced from the present analysis and our physical interpretation is presented, and is shown to be consistent with previous flow visualisation studies.
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Xiang, X., und H. Babinsky. „Corner effects for oblique shock wave/turbulent boundary layer interactions in rectangular channels“. Journal of Fluid Mechanics 862 (16.01.2019): 1060–83. http://dx.doi.org/10.1017/jfm.2018.983.
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In a rectangular cross-section wind tunnel, a separated oblique shock reflection is set to interact with the turbulent boundary layer (oblique shock wave/turbulent boundary layer interaction (SBLI)) both on the bottom wall and in the corners formed by the intersection of the floor with the sidewalls. To examine how corner separations can affect the ‘quasi-two-dimensional’ main interaction and by what mechanisms this is achieved, an experimental investigation has been conducted. This examines how modifications to the corner separation affect an $M=2.5$ oblique shock reflection. The nature of the flow field is studied using flow visualisation, pressure-sensitive paint and laser Doppler anemometry. The results show that the size and shape of central separation vary considerably when the onset and magnitude of corner separation changes. The primary mechanism explaining the coupling between these separated regions appears to be the generation of compression waves and expansion fans as a result of the displacement effect of the corner separation. This is shown to modify the three-dimensional shock structure and alter the adverse pressure gradient experienced by the tunnel floor boundary layer. It is suggested that a typical oblique SBLI in rectangular channels features several zones depending on the relative position of the corner waves and the main interaction domain. In particular, it has been shown that the position of the corner ‘shock’ crossing point, found by approximating the corner compression waves by a straight line, is a critical factor determining the main separation size and shape. Thus, corner effects can substantially modify the central separation. This can cause significant growth or contraction of the separation length measured along the symmetry line from the nominally two-dimensional baseline value, giving a fivefold increase from the smallest to the largest observed value. Moreover, the shape and flow topology of the centreline separation bubble is also considerably changed by varying corner effects.
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Shaheed, Kashif, Piotr Szczuko, Qaisar Abbas, Ayyaz Hussain und Mubarak Albathan. „Computer-Aided Diagnosis of COVID-19 from Chest X-ray Images Using Hybrid-Features and Random Forest Classifier“. Healthcare 11, Nr. 6 (13.03.2023): 837. http://dx.doi.org/10.3390/healthcare11060837.
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In recent years, a lot of attention has been paid to using radiology imaging to automatically find COVID-19. (1) Background: There are now a number of computer-aided diagnostic schemes that help radiologists and doctors perform diagnostic COVID-19 tests quickly, accurately, and consistently. (2) Methods: Using chest X-ray images, this study proposed a cutting-edge scheme for the automatic recognition of COVID-19 and pneumonia. First, a pre-processing method based on a Gaussian filter and logarithmic operator is applied to input chest X-ray (CXR) images to improve the poor-quality images by enhancing the contrast, reducing the noise, and smoothing the image. Second, robust features are extracted from each enhanced chest X-ray image using a Convolutional Neural Network (CNNs) transformer and an optimal collection of grey-level co-occurrence matrices (GLCM) that contain features such as contrast, correlation, entropy, and energy. Finally, based on extracted features from input images, a random forest machine learning classifier is used to classify images into three classes, such as COVID-19, pneumonia, or normal. The predicted output from the model is combined with Gradient-weighted Class Activation Mapping (Grad-CAM) visualisation for diagnosis. (3) Results: Our work is evaluated using public datasets with three different train–test splits (70–30%, 80–20%, and 90–10%) and achieved an average accuracy, F1 score, recall, and precision of 97%, 96%, 96%, and 96%, respectively. A comparative study shows that our proposed method outperforms existing and similar work. The proposed approach can be utilised to screen COVID-19-infected patients effectively. (4) Conclusions: A comparative study with the existing methods is also performed. For performance evaluation, metrics such as accuracy, sensitivity, and F1-measure are calculated. The performance of the proposed method is better than that of the existing methodologies, and it can thus be used for the effective diagnosis of the disease.
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Stryczniewicz, Wit. „Quantitative Visualisation of Compressible Flows“. Transactions on Aerospace Research 2018, Nr. 1 (01.03.2018): 137–45. http://dx.doi.org/10.2478/tar-2018-0009.
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Abstract The paper demonstrates the feasibility of quantitative flow visualisation methods for investigation of transonic and supersonic flows. Two methods and their application for retrieving compressible flow field properties has been described: Background Oriented Schlieren (BOS) and Particle Image Velocimetry (PIV). Recently introduced BOS technique extends the capabilities of classical Schlieren technique by use of digital image processing and allow to measure density gradients field. In the presented paper a review of applications of BOS technique has been presented. The PIV is well established technique for whole field velocity measurements. This paper presents application of PIV for determination of the shock wave position above airfoil in transonic flow regime. The study showed that application of quantitative flow visualisation techniques allows to gain new insights on the complex phenomenon of supersonic and transonic flow over airfoils like shock-boundary layer interaction and shock induced flow separation.
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Zhong, S., C. Kittichaikan, H. P. Hodson und P. T. Ireland. „Visualisation of turbulent spots under the influence of adverse pressure gradients“. Experiments in Fluids 28, Nr. 5 (03.05.2000): 385–93. http://dx.doi.org/10.1007/s003480050398.
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Bozic, Bojan, Andre Rios und Sarah Jane Delany. „Comparing tagging suggestion models on discrete corpora“. International Journal of Web Information Systems 16, Nr. 2 (11.05.2020): 201–21. http://dx.doi.org/10.1108/ijwis-08-2019-0035.
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Purpose This paper aims to investigate the methods for the prediction of tags on a textual corpus that describes diverse data sets based on short messages; as an example, the authors demonstrate the usage of methods based on hotel staff inputs in a ticketing system as well as the publicly available StackOverflow corpus. The aim is to improve the tagging process and find the most suitable method for suggesting tags for a new text entry. Design/methodology/approach The paper consists of two parts: exploration of existing sample data, which includes statistical analysis and visualisation of the data to provide an overview, and evaluation of tag prediction approaches. The authors have included different approaches from different research fields to cover a broad spectrum of possible solutions. As a result, the authors have tested a machine learning model for multi-label classification (using gradient boosting), a statistical approach (using frequency heuristics) and three similarity-based classification approaches (nearest centroid, k-nearest neighbours (k-NN) and naive Bayes). The experiment that compares the approaches uses recall to measure the quality of results. Finally, the authors provide a recommendation of the modelling approach that produces the best accuracy in terms of tag prediction on the sample data. Findings The authors have calculated the performance of each method against the test data set by measuring recall. The authors show recall for each method with different features (except for frequency heuristics, which does not provide the option to add additional features) for the dmbook pro and StackOverflow data sets. k-NN clearly provides the best recall. As k-NN turned out to provide the best results, the authors have performed further experiments with values of k from 1–10. This helped us to observe the impact of the number of neighbours used on the performance and to identify the best value for k. Originality/value The value and originality of the paper are given by extensive experiments with several methods from different domains. The authors have used probabilistic methods, such as naive Bayes, statistical methods, such as frequency heuristics, and similarity approaches, such as k-NN. Furthermore, the authors have produced results on an industrial-scale data set that has been provided by a company and used directly in their project, as well as a community-based data set with a large amount of data and dimensionality. The study results can be used to select a model based on diverse corpora for a specific use case, taking into account advantages and disadvantages when applying the model to your data.
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El motassadeq, Ahmed, Hassan Chehouani, Mohamed Waqif und Sauveur Benet. „Simulation et Visualisation de la Couche Limite Thermique au-Dessous d’un Disque Horizontal“. Journal of Renewable Energies 3, Nr. 1 (30.06.2000): 57–69. http://dx.doi.org/10.54966/jreen.v3i1.911.
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Ce travail concerne la simulation numérique et la visualisation de la couche limite thermique au voisinage d’un disque horizontal en convection libre dans l’air. Le modèle que nous avons développé est fondé sur la résolution des équations de Navier-Stokes couplées à l’équation de l’énergie pour décrire l’écoulement et le transfert de chaleur. Nous avons utilisé la technique des volumes finis pour résoudre numériquement les équations. On simule ainsi le champ de température et les lignes de courant dans le milieu. Les résultats mettent en évidence la présence de forts gradients de température entraînant l’établissement d’une mince couche limite thermique localisée près du disque. La visualisation de cette couche a été effectuée par la technique optique d’ombroscopie. Une approche numérique a été suggérée pour expliquer la caustique de la couche limite thermique qui joue le rôle d’une lentille thermique.
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Mohammed-Taifour, A., Q. Schwaab, J. Pioton und J. Weiss. „A new wind tunnel for the study of pressure-induced separating and reattaching flows“. Aeronautical Journal 119, Nr. 1211 (Januar 2015): 91–108. http://dx.doi.org/10.1017/s0001924000010265.
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AbstractThe design, construction, and validation of a new academic wind tunnel is described in detail. The wind tunnel is of a classical, blow-down type and generates a pressure-induced, turbulent separation bubble on a flat test surface by a combination of adverse and favorable pressure gradients. The Reynolds number, based on momentum thickness just upstream of separation, is Reθ≃ 5,000 at a free-stream velocity ofUref= 25ms−1. The length of the separation bubble is estimated at 0°42 ± 0°02m by three different methods. Results of a numerical simulation demonstrate the absence of flow separation in the wind-tunnel contraction. This results in a turbulence level of about 0·05% in the test section. Oil-film visualisation experiments show that the flow near the wall is strongly three-dimensional in the recirculating region and that the topology of the limiting streamlines is consistent with experiments performed on configurations with fixed separation. Finally, spatial variations of the forward-flow fraction have been documented using a thermal-tuft probe and are shown to compare well with the results of the oil-film visualisation.