Visual saliency guided textured model simplification

Mesh geometry can be used to model both object shape and details. If texture maps are involved, it is common to let mesh geometry mainly model object shapes and let the texture maps model the most object details, optimising data size and complexity of an object. To support efficient object rendering and transmission, model simplification can be applied to reduce the modelling data. However, existing methods do not well consider how object features are jointly represented by mesh geometry and texture maps, having problems in identifying and preserving important features for simplified objects. To address this, we propose a visual saliency detection method for simplifying textured 3D models. We produce good simplification results by jointly processing mesh geometry and texture map to produce a unified saliency map for identifying visually important object features. Results show that our method offers a better object rendering quality than existing methods

Modélisation et optimisation du comportement mécanique vibratoire d'une machine de fatigue de torsion

Il y a encore quelques décennies, le modèle de comportement admis pour les métaux face à la fatigue pouvait être représenté par une courbe de Wöhler, courbe qui tendait, après quelques millions de cycles, vers une asymptote horizontale que l'on définit par limite d'endurance. Aujourd'hui, grâce à l'arrivée de nouvelles machines de fatigue piezo-électriques, qui travaillent en résonance à très hautes fréquences, on montre que les limites d'endurance établies à quelques millions de cycles deviennent obsolètes. Ces machines permettent d'atteindre aisément le milliard de cycles en moins d'une journée et ainsi, caractériser le comportement en fatigue bien au-delà des présupposées limites d'endurance. Ce domaine de la fatigue à très grand nombre de cycles est caractérisé par le terme gigacyclique. Pour des raisons techniques, les travaux en fatigue gigacyclique se sont concentrés jusqu'à maintenant autour des sollicitations en traction-compression. L'objet du présent article est de proposer un système nouveau de fatigue gigacyclique travaillant en cisaillement

The impact of electronic health records (EHR) data continuity on prediction model fairness and racial-ethnic disparities

Electronic health records (EHR) data have considerable variability in data completeness across sites and patients. Lack of "EHR data-continuity" or "EHR data-discontinuity", defined as "having medical information recorded outside the reach of an EHR system" can lead to a substantial amount of information bias. The objective of this study was to comprehensively evaluate (1) how EHR data-discontinuity introduces data bias, (2) case finding algorithms affect downstream prediction models, and (3) how algorithmic fairness is associated with racial-ethnic disparities. We leveraged our EHRs linked with Medicaid and Medicare claims data in the OneFlorida+ network and used a validated measure (i.e., Mean Proportions of Encounters Captured [MPEC]) to estimate patients' EHR data continuity. We developed a machine learning model for predicting type 2 diabetes (T2D) diagnosis as the use case for this work. We found that using cohorts selected by different levels of EHR data-continuity affects utilities in disease prediction tasks. The prediction models trained on high continuity data will have a worse fit on low continuity data. We also found variations in racial and ethnic disparities in model performances and model fairness in models developed using different degrees of data continuity. Our results suggest that careful evaluation of data continuity is critical to improving the validity of real-world evidence generated by EHR data and health equity

Effect of additives on microstructure of coal-based graphite

The Taixi anthracite was used as the raw materials, and mixed with different masses of additives, namely silicon oxide, titanium oxide, and iron oxide, to prepare the coal-based graphite by high temperature graphitization. The microstructure of coal-based graphite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser confocal Raman spectroscopy (Raman) and Specific surface area and porosity analyzer.The results show that the graphitization degree of the coal-based graphite can reach over 89% after high temperature heat treatment at 2800 °C , which significantly improves the microcrystalline structure of anthracite and achieves orderly rearrangement of sp2 hybrid carbon atoms in the coal. Under the same additive mixing level, the graphitization degree and stacking height of coal-based graphite with titanium dioxide as additive are relatively high, the difference between the layer spacing and the ideal graphite layer spacing is the smallest, and the degree of ordering of carbon materials is the highest. The Raman spectroscopy results showed that the order degree of coal -based graphite prepared under different additives was significantly different, and the order degree of TXSC3, TXTC2 and TXIC3 coal-based graphite was the highest among the additives. Under the electron microscope, it is found that under the conditions of three additives, the scales, spherical and two shapes of coal-based graphite can be prepared separately. It can be seen from the specific surface area and pore size distribution data of coal-based graphite that they have similar low-temperature nitrogen adsorption-desorption isotherms

The increased functional connectivity between the locus coeruleus and supramarginal gyrus in insomnia disorder with acupuncture modulation

BackgroundInsomnia disorder (ID) seriously affects the quality of people’s daily life, and acupuncture is an effective therapy for it. As an essential component of the upward activation system, the locus coeruleus (LC) plays a crucial role in sleep–wake regulation, its aberrant functional connectivity (FC) is found to be involved in ID. The purpose of this study was to explore the modulation effect of acupuncture on the resting state FC of LC in ID patients.Methods60 ID patients were recruited and randomly assigned to real acupuncture (RA) or sham acupuncture (SA) treatment. Resting-state functional magnetic resonance imaging (fMRI) data were collected before and after the treatment. With LC as the region of interest, the FC method was adopted to examine acupuncture-related modulation of intrinsic connectivity in ID patients. The Pittsburgh Sleep Quality Index (PSQI), Hyperarousal Scale (HAS), and actigraphy were used to assess sleep quality and cortical hyperarousal states. Associations between clinical outcomes and FC features were calculated using Pearson’s correlation analysis.ResultsThe improvement in sleep quality and hyperarousal in the RA group was greater than that in the SA group. After treatment, the FC between the LC and left inferior frontal gyrus (IFG) decreased in the RA group. The FC between the LC and left insula and supramarginal gyrus (SMG) was higher in the RA group. The change of LC FC values with the SMG was negatively associated with the change in PSQI scores.ConclusionAcupuncture can modulate FC between the LC and IFG, insular gyrus, and SMG. This may imply the potential mechanism of acupuncture treatment for insomnia

Development of a torsional gigacyclic fatigue machine for high-strength metallic materials

Ce travail de recherche donc concerne l'étude du système ultrasonique de fatigue en torsion de type indirect pouvoir étudier le comportement des matériaux métalliques à haute résistance, essentiellement au domaine de fatigue gigacyclique. Il existe actuellement deux types de système ultrasonique de torsion : un système qualifié de "direct" dans lequel le convertisseur délivre une rotation permettant, de manière simple et directe, la mise en vibration de torsion du système ; un système qualifié de "indirect" qui utilise un convertisseur longitudinal et nécessite une transformation en rotation pour créer la vibration en résonance de torsion. Premièrement, la présente d'étude sur le système indirect permet de comprendre son comportement de fatigue et ses propriétés. Cette étude est présentée à partir des calculs analytiques et numériques afin de dimensionner et modéliser ce système. Ensuite, l'optimisation du système à l'aide de la méthode des éléments finis est réalisée et un système plus effectif et plus robuste est obtenu. Des comparaisons entre les résultats numériques et les résultats de calibration sont proposées et une interprétation des écarts constatés est proposée avec les nouvelles simulations numériques. Deuxièmement, une campagne expérimentale à 20 kHz au-delà de 10⁸ cycles est menée en utilisant le système optimisé sur les aciers 16MnCr5 et 50CrV4 du projet FreqTigue. La méthode de l'escalier est utilisé dans les essais afin de décrire la courbe S-N, d'estimer la résistance à la fatigue et d'obtenir la durée de vie en fatigue. Des comparaisons des courbes S-N à différentes fréquences et sollicitations sont présentées. Les surfaces de rupture des éprouvettes sont analysées pour tenter d'identifier les causes de la rupture.This research work concerns the study of the torsional ultrasonic fatigue system of indirect type which is able to study the behavior of high-strength metallic materials, mainly in the domain of gigacyclic fatigue. With the developments of technique, there are currently two types of ultrasonic torsional system: the first one is described as "direct" and its converter delivers a rotation which allows the system vibrate in torsion; the second one is described as "indirect", which uses a longitudinal converter and requires the transformation of a translation into a rotation to create a desired torsional resonant vibration in the specimen. Firstly, the study of the indirect system could understand the fatigue behavior and the properties of this system. This study is presented with the analytical and numerical calculations in order to determine and model the indirect system. Then, the optimization of this system by using the finite element method is performed and a more efficient and robust system is developed. Some comparisons between the numerical results and calibration’s results are proposed and an interpretation of differences is proposed by using new numerical simulations. Secondly, the tests of the 16MnCr5 and 50CrV4 steels of the FreqTigue project are carried out at 20 kHz and beyond 10⁸ cycles by using this optimized system. The staircase method is used in the tests to describe the S-N curve, to estimate the fatigue strength and to obtain the fatigue life. Then, the comparisons of the S-N curves at different vibration frequencies and stresses are presented, and the ruptured surfaces of the specimen are also analyzed to identify the causes of the rupture