Publications

24/05/2024

Thermomechanical shape memory testing of 4D printed novel material rhombus-shape structure

Authors : AKBAR, Ijaz EL HADROUZ, Mourad EL MANSORI, Mohamed TARFAOUI, Mostapha
Publisher : Elsevier BV
4D printing of functional energy generation/absorption structures by material extrusion technique can capitalize on the exciting applications in intelligent damping devices and patterns to deform spontaneously. This paper investigated the capitalization of this acquired knowledge by studying the shape memory effects of a functional rhombus shape structure. Initially, the shape memory characteristics of energy absorption and dissipation capacity were analyzed using dynamic mechanical testing to develop databases to gather thermophysical data before expressing the material behavior and recovery performances of printed shape memory structures. Then a complete thermomechanical cycle (shape programming and recovery) on 4D printed amorphous and semi-crystalline shape memory polymers exhibited deep insights into shape memory performance. The performance factors (i.e., recovery and fixity ratios) are influenced by variable printing parameters (i.e., layer height, printing temperature, and speed) and stimuli-based testing conditions. Results reveal both materials have significant shape memory effects with a maximum recovery ratio of up to 92.30 ± 0.32% from the programmed configuration. The amorphous polymer was extremely affected by printing temperature, whilst the semi-crystalline was influenced heavily by the interaction of all three parameters. Finally, shape memory effects predicted by a high-order design model and compared with experimental results showed negligible error. The analyses and assessments presented in this paper are adequate to understand the shape memory behavior under process control parameters to establish a data-driven model of a 4D printed semi-crystalline and amorphous polymer reactive to thermal stimuli.
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24/05/2024

Global Sagittal Angle and T9-tilt seem to be the most clinically and functionally relevant global alignment parameters in patients with Adult Spinal Deformity

Authors : NASSIM, Nabil MEKHAEL, Elio RACHKIDI, Rami El SAADE, Maria AYOUB, Elma RTEIL, Ali JABER, Elena CHAAYA, Celine REHAYEM, Rami ABI NAHED, Julien KARAM, Mohamad GHANEM, Ismat MASSAAD, Abir ASSI, Ayman
Publisher : Elsevier BV
Introduction Radiographic analysis is necessary for the assessment and the surgical planning in adults with spinal deformity (ASD). Restoration of global alignment is key to improving patient's quality of life. However, the large number of existing global alignment parameters can be confusing for surgeons. Research question To determine the most clinically and functionally relevant global alignment parameters in ASD. Material and methods ASD and controls underwent full body biplanar X-ray to calculate global alignment parameters: odontoid to hip axis angle (OD-HA), global sagittal angle (GSA), global tilt (GT), SVA, center of auditory meatus to hip axis (CAM-HA), SSA, T1-tilt and T9-tilt. All subjects filled HRQoL questionnaires: ODI, SF-36, VAS for pain and BDI (Beck's Depression Inventory). 3D gait analysis was performed to calculate kinematic and spatio-temporal parameters. A machine learning model predicted gait parameters and HRQoL scores from global alignment parameters. Results 124 primary ASD and 47 controls were enrolled. T9 tilt predicted the most BDI (31%), hip flexion/extension during gait (36%), and double support time (39%). GSA predicted the most ODI (26%), thorax flexion/extension during gait (33%), and cadence (36%). Discussion and conclusion Among all global alignment parameters, GSA, evaluating both trunk shift and knee flexion, and T9 tilt, evaluating the shift of the center of mass, were the best predictors for most of HRQoL scores and gait kinematics. Therefore, we recommend using GSA and T9 tilt in clinical practice when evaluating ASD because they represent the most quality of life and functional kinematic of these patients.
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16/05/2024

DRGAT: Dual-relational graph attention networks for aspect-based sentiment classification

Authors : YOU, Lan PENG, Jiaheng JIN, Hong CLARAMUNT, Christophe ZENG, Haoqiu ZHANG, Zhen
Publisher : Elsevier BV
Aspect-based sentiment classification has become a popular topic in natural language processing. Exploiting dependency syntactic information with graph neural networks has recently become a popular trend. Despite their success, methods that rely heavily on a dependency tree face major challenges. This concerns the alignment of aspects and their word sentiments due to the richness of the language and the fact that a dependency tree might produce noisy signals from unrelated associations. This paper introduces a Dual-Relational Graph Attention Network (DRGAT) that fully exploits syntactic structural information and then the sentiment-aware context (e.g., phrase segmentation and hierarchical structure) of the constituent tree of a sentence. Additional constituency and dependency attention mechanisms provide comprehensive syntactic information across words, thereby enabling an accurate connection between aspect words and corresponding sentiment words. Considering that the original parsed constituency tree may have a large depth, this could lead to words being far apart increasing the computational overhead. The constituency tree of each sentence is dynamically reconstructed by determining the importance of each relational node. Extensive experimental results on six English datasets demonstrated that fully exploiting syntactic information can achieve excellent sentiment classification results.
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16/05/2024

A Quantitative and Qualitative Experimental Framework for the Evaluation of Urban Soundscapes: Application to the City of Sidi Bou Saïd

Authors : HAMMAMI, Mohamed Amin CLARAMUNT, Christophe
Publisher : MDPI AG
This research introduces an experimental framework based on 3D acoustic and psycho-acoustic sensors supplemented with ambisonics and sound morphological analysis, whose objective is to study urban soundscapes. A questionnaire that highlights the differences between what has been measured and what has been perceiveSd by humans complements the quantitative approach with a qualitative evaluation. The comparison of the measurements with the questionnaire provides a global vision of the perception of these soundscapes, as well as differences and similarities. The approach is experimented within the historical center of the Tunisian city of Sidi Bou Saïd, demonstrating that from a range of complementary protocols, a soundscape environment can be qualified. This framework provides an additional dimension to urban planning studies.
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15/05/2024

Do urban renewal programs make suburbs safer? A fine-grained GIS and space syntax study of an urban renewal project in the city of Toulouse

Authors : LAOUAR, Dounia MOKRANE, Youcef CLARAMUNT, Christophe
Publisher : Informa UK Limited - Taylor & Francis
This paper evaluates the impact of urban renewal programs (PRU) on creating a safe environment. People’s perceptions of PRU and its impact on security were collected through questionnaires and sketch maps. This study applies a space syntax approach to analyse the spatial and structural properties of successive urban space evolutions and compare them with people’s perceptions of security. The findings reveal a strong correlation between areas with high levels of social housing concentration, poverty rates and insecurity. Surprisingly, visually controlled areas are vulnerable and attractive locations for drug trafficking. Density indicators have a minor influence on the perception of insecurity.
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15/05/2024

Jumeaux numériques : le projet JENII cherche à innover dans la formation aux procédés de fabrication

Authors : BAUDOUIN, Cyrille URIBE, David FLEURY, Sylvain
Publisher : Fédération Forge Fonderie
Le concept de jumeau numérique offre une multitude d'applications et d'utilisations dans divers domaines. Tout d'abord, il permet de simuler et de tester des scénarios virtuels avant de les implémenter dans le monde réel. Cela peut être particulièrement utile dans le domaine de la conception et du prototypage, où les ingénieurs peuvent explorer différentes configurations et identifier les problèmes potentiels avant même de commencer la production physique. De plus, les jumeaux numériques sont largement utilisés dans la fabrication prédictive. En utilisant des modèles avancés alimentés par des données en temps réel, ils peuvent prédire les performances futures des équipements industriels, anticiper les pannes et optimiser les paramètres de fonctionnement pour améliorer l'efficacité opérationnelle. Le projet JENII (Jumeaux d’Enseignement Numériques Immersifs et Interactifs), mené par l’ENSAM en collaboration avec le CESI, le CNAM et le CEA, et financé par l’ANR, vise à développer des jumeaux numériques pour la formation, particulièrement pour les procédés comme la forge et la fonderie, entre autres. JENII vise à révolutionner l’éducation, en créant une suite de jumeaux numériques pour des cas d’applications d’ingénierie. En intégrant des environnements virtuels avec des interactions en temps réel, ce projet offre aux apprenants une expérience d'apprentissage innovante qui complète les méthodes traditionnelles d'enseignement.
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15/05/2024

A location-based model using GIS with machine learning, and a human-based approach for demining a post-war region

Authors : SALIBA, Adib TOUT, Kifah ZAKI, Chamseddine CLARAMUNT, Christophe
Publisher : Informa UK Limited - Taylors & Francis
Locating and removing landmines and other ERW (Explosive Remnants of War) is dangerous, hazardous, and time-consuming. It requires implementing multilevel on-site surveys: general non-technical surveys to mark the areas affected and technical surveys to determine the perimeter of related minefields. This paper introduces a landmine location-based prediction model, combining military experience with machine-learning techniques and spatiotemporal data, by introducing a new approach for area selection and adding military-based features for context modelling and model training. Besides predicting landmine’s location areas, this model classifies the affected regions by priority and difficulty of clearance, in such a way as to minimise the long time needed by surveys and reduce the danger related to that task, thus providing the clearance organisations with a good resource allocation for their operations. We applied several machine learning techniques that combine Support Vector Machine (SVM), Random Forest (RF), and Extreme Gradient Boosting (XGBOOST), taking into consideration the imbalanced data problem and tweaking for the best performance and accuracy. The experimental results show that the model has the potential to provide reliable predictions and valuable services for demining operations on the field.
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15/05/2024

Enhancing metal-forming predictions with VR-infused digital twin models

Authors : URIBE, David BAUDOUIN, Cyrille LOCARD, Yoan DURAND, Camille BIGOT, Regis
Publisher : Materials Research Forum LLC
This article presents a two-step method to enhance metal-forming predictions by integrating Virtual Reality (VR) into Digital Twin models, focusing on single-blow cold copper upsetting operations. The process begins with developing a real-time predictive surrogate model that considers actual process parameters, acting as a crucial link between conventional numerical simulations and immediate decision-making. Subsequently, the surrogate model is integrated into a realistic VR environment, aligned with the experimental forging setup. The study underscores the need and potential advantages of real-time digital twins in the forging field, emphasizing the bridging capability between numerical simulations and instant decision-making through predictive modeling and immersive virtual environments.
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14/05/2024

Kinetic, Products and Shrinkage for the Pyrolysis of Flax Fibers

Authors : DHAHAK, Asma CÉZARD, Laurent BAUMBERGER, Stéphanie PEIXINHO, Jorge
Publisher :
Biomass pyrolysis is a thermochemical process used for renewable products and energies. However, there are still issues that need to be addressed for process modeling and optimization. This study focuses on the relationship between heating rate, shrinkage, and products from flax fibers using thermogravimetric analysis (TGA), microscopic observation, and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). TGA confirms sequential evaporation of water then decomposition of hemicellulose, cellulose, and lignin. Observations from the micro-reactor show that flax fibers undergo shrinkage within the temperature range of 335 to 370 °C, depending on the heating rate. Pyrolysis products were analyzed using Py-GC/MS at four different final temperatures from 350 to 500 °C, revealing the presence of anhydrosugars, furans, ketones, phenols, esters, alcohols, aldehydes, and acids. The results indicate a correlation between temperature and the increase in furans and ketones. The analysis suggests that furans and ketones are associated with shrinkage.
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14/05/2024

Non destructive control of permanent magnet rotors in a perspective of electric motor circularity

Authors : SAGNA, Alph MANSOUR, G. CLENET, Stephane PERRY, Nicolas
Publisher : Elsevier BV
This work presents an innovative non destructive control process in order to guide for the end of life (re-use or recycling) of permanents magnets (PM) rotors of electric motors. The process is based on the measurement of the external field produced by the PM rotors. A Finite Element model of the rotor and its environment has been used to simulate a process of classification of the geometry of PM rotors, crucial information for the disassembling of the PM. Firstly, using a finite element model, we were able to investigate the field distribution outside the rotor of the magnetic flux density for different PM rotors designs. From this information, we can set up a classification methodology, based on the Central Voronoi Tessellation (CVT) method, which can help to identify how the PM are inserted within the rotor. This information can be very useful to choose PM disassembling process that should be applied.
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