Conception d'un matériau acoustique à base de fibres naturelles d'asclépiade

Dans un contexte où la pollution, qu'elle soit sonore ou environnementale, continue de s'accroître malgré les efforts déployés, ce projet de recherche propose la conception d'un absorbant acoustique à base de fibres naturelles possédant un fort potentiel acoustique, la soie d'asclépiade. Produite au Québec, cette fibre permet de respecter les grands principes du développement durable. Pour assurer une conception optimale, la démarche proposée passe par l'adaptation d'un modèle acoustique micro-macro de matériaux fibreux afin de relier le comportement acoustique aux paramètres de conception, qui sont l'orientation des fibres, leurs diamètres ainsi que la masse volumique apparente de l'agrégat. En premier lieu, la validité du modèle micro-macro pour le cas des fibres creuses est investiguée. Pour ce faire, une correction de l'expression de la porosité du matériau est proposée afin d'alimenter le modèle micro-macro avec la porosité externe aux fibres uniquement, comme cela aurait été le cas pour des fibres pleines. Cette approche est validée à l'aide de mesures directes et ultrasonores de la porosité, montrant que la porosité « acoustique » est inférieure à la porosité totale mesurée directement. Les résultats du modèle sont ensuite comparés avec des mesures en tube d'impédance d'échantillons de fibres en vrac à différents taux de compaction. On peut observer que le comportement global de la fibre est bien capté par le modèle, qui se compare bien avec le modèle classique de Miki. On y observe aussi que la résistivité mesurée suit bien les prédictions du modèle pour un arrangement de fibres dans le plan perpendiculaire au sens de propagation de l'onde acoustique. C'est aussi cet arrangement qui permet d'obtenir les meilleurs résultats en termes d'absorption acoustique. Ensuite, une modélisation de type double porosité avec une loi des mélanges est proposée afin de capter l'effet acoustique de la fibre creuse. On peut observer que pour ces dimensions de fibres, l'effet n'est pas très marqué car la perméabilité du domaine microporeux est faible. Par contre, la loi des mélanges permet de bien corriger le modèle proposé. En second lieu, des tests de fabrication sont réalisés à partir de mats d'asclépiade. Le mat est un mélange d'asclépiade et de fibres bicomposantes formé d'un empilement thermolié de voiles préalablement cardés. Les mats sont compactés et thermoliés de façon à obtenir un matériau d'épaisseur et de masse volumique apparente déterminées. Les meilleurs résultats ont été obtenus sous presse chauffante. Le matériau résultant est ensuite testé et comparé à la mousse de mélamine, une référence en termes d'absorbant acoustique léger. La démarche suivie dans ces travaux a permis de fabriquer un matériau acoustique exploitant le plein potentiel acoustique de la soie d'asclépiade grâce à une optimisation via le modèle prédictif proposé. Pour des développements futurs, il serait intéressant d'étudier les effets de fibres creuses de plus grandes dimensions, en plus de valider l'applicabilité du procédé de fabrication sur ces fibres

Preliminary development of an active planar upper limb rehabilitation robotic device

This paper presents the development of a low-cost active planar upper limb rehabilitation robotic device, which aims to help in the rehabilitation process of people living with movement disorders. Many people living with conditions such as cerebral palsy, stroke, spinal cord injury or muscular dystrophy experience upper limb impairments (muscle spasticity, lack of selective motor control, muscle weakness or tremors), and require physical and occupational therapy to maintain or gain motor performance. The proposed device is designed to be fixed on a table. Direct current (DC) motors control the two degrees of freedom (DOF) of the mechanism. The user interacts with the device using a handle. The device is designed so that the handle stays in the same orientation all the time. The device offers different levels of assistance to guide planar movements, going from a complete assistance, where the user is guided by the mechanism that performs predefined movements recorded by the therapist, to the addition of resistance during the movement, where the user moves the end effector without the help of the mechanism and the latter adds perturbations

A cable-suspended intelligent crane assist device for the intuitive manipulation of large payloads

This paper presents a cable-suspended crane system to assist operators in moving and lifting large payloads. The main objective of this work is to develop a simple and reliable system to help operators in industry to be more productive while preventing injuries. The system is based on the development of a precise and reliable cable angle sensor and a complete dynamic model of the system. Adaptive horizontal and vertical controllers designed for direct physical human-robot interaction are then proposed. Different techniques are then proposed to estimate the payload acceleration in order to increase the controller performances. Finally, experiments performed on a full-scale industrial system are presented

JACO assistive robotic device : empowering people with disabilities through innovative algorithms

JACO is a commercially available robotic assistive device designed to help people with upper body disabilities gaining more autonomy in their daily life. The device consists of an arm and hand (gripper) mounted on a power wheelchair. This assistance is possible through basic functions such as tri-dimensional displacement of the gripper in space, finger opening and closing and orientation of the wrist. Although these basic functionalities allow the user to perform many tasks, advanced functionalities were required to further empower the users. This paper presents advanced functionalities that were implemented in JACO in order to increase the users’ safety and to enhance their autonomy by increasing the number of achievable tasks and diminishing the time and effort needed to achieve them

An articulated assistive robot for intuitive hands-on-payload manipulation

This paper presents an intelligent assistive robot designed to help operators in lifting and moving large payloads through direct physical contact (hands-on-payload mode). The mechanical design of the robot is first presented. Although its kinematics are similar to that of a cable-suspended system, the proposed mechanism is based on articulated linkages, thereby allowing the payload to be offset from the rail support on which it is suspended. A dynamic model of the robot is then developed. It is shown that a simplified dynamic model can be obtained using geometric assumptions. Based on the simplified dynamic model, a controller is then presented that handles the physical human-robot interaction and that provides the operator with an intuitive direct control of the payload. Experimental validation on a full-scale prototype is presented in order to demonstrate the effectiveness of the proposed robot and controller

Kinova modular robot arms for service robotics applications

This article presents Kinova's modular robotic systems, including the robots JACO2 and MICO2, actuators and grippers. Kinova designs and manufactures robotics platforms and components that are simple, sexy and safe under two business units: Assistive Robotics empowers people living with disabilities to push beyond their current boundaries and limitations while Service Robotics empowers people in industry to interact with their environment more efficiently and safely. Kinova is based in Boisbriand, Québec, Canada. Its technologies are exploited in over 25 countries and are used in many applications, including as service robotics, physical assistance, medical applications, mobile manipulation, rehabilitation, teleoperation and in research in different areas such as computer vision, artificial intelligence, grasping, planning and control interfaces. The article describes Kinova's hardware platforms, their different control modes (position, velocity and torque), control features and possible control interfaces. Integration to other systems and application examples are also presented

Inherited variants in CHD3 show variable expressivity in Snijders Blok-Campeau syndrome

Purpose: Common diagnostic next-generation sequencing strategies are not optimized to identify inherited variants in genes associated with dominant neurodevelopmental disorders as causal when the transmitting parent is clinically unaffected, leaving a significant number of cases with neurodevelopmental disorders undiagnosed. Methods: We characterized 21 families with inherited heterozygous missense or protein-truncating variants in CHD3, a gene in which de novo variants cause Snijders Blok-Campeau syndrome. Results: Computational facial and Human Phenotype Ontology–based comparisons showed that the phenotype of probands with inherited CHD3 variants overlaps with the phenotype previously associated with de novo CHD3 variants, whereas heterozygote parents are mildly or not affected, suggesting variable expressivity. In addition, similarly reduced expression levels of CHD3 protein in cells of an affected proband and of healthy family members with a CHD3 protein-truncating variant suggested that compensation of expression from the wild-type allele is unlikely to be an underlying mechanism. Notably, most inherited CHD3 variants were maternally transmitted. Conclusion: Our results point to a significant role of inherited variation in Snijders Blok-Campeau syndrome, a finding that is critical for correct variant interpretation and genetic counseling and warrants further investigation toward understanding the broader contributions of such variation to the landscape of human disease

Inherited variants in CHD3 show variable expressivity in Snijders Blok-Campeau syndrome

Purpose Common diagnostic next-generation sequencing strategies are not optimized to identify inherited variants in genes associated with dominant neurodevelopmental disorders as causal when the transmitting parent is clinically unaffected, leaving a significant number of cases with neurodevelopmental disorders undiagnosed. Methods We characterized 21 families with inherited heterozygous missense or protein-truncating variants in CHD3, a gene in which de novo variants cause Snijders Blok-Campeau syndrome. Results Computational facial and Human Phenotype Ontology–based comparisons showed that the phenotype of probands with inherited CHD3 variants overlaps with the phenotype previously associated with de novo CHD3 variants, whereas heterozygote parents are mildly or not affected, suggesting variable expressivity. In addition, similarly reduced expression levels of CHD3 protein in cells of an affected proband and of healthy family members with a CHD3 protein-truncating variant suggested that compensation of expression from the wild-type allele is unlikely to be an underlying mechanism. Notably, most inherited CHD3 variants were maternally transmitted. Conclusion Our results point to a significant role of inherited variation in Snijders Blok-Campeau syndrome, a finding that is critical for correct variant interpretation and genetic counseling and warrants further investigation toward understanding the broader contributions of such variation to the landscape of human disease

Increased Levels of Leukocyte-Derived MMP-9 in Patients with Stable Angina Pectoris

Objective: There is a growing interest for matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in plasma as novel biomarkers in coronary artery disease (CAD). We aimed to identify the sources of MMP-8, MMP-9, TIMP-1 and TIMP-2 among peripheral blood cells and further explore whether gene expression or protein release was altered in patients with stable angina pectoris (SA). Methods: In total, plasma MMP-9 was measured in 44 SA patients and 47 healthy controls. From 10 patients and 10 controls, peripheral blood mononuclear cells (PBMC) and neutrophils were isolated and stimulated ex vivo. MMPs, TIMPs and myeloperoxidase were measured in plasma and supernatants by ELISA. The corresponding gene expression was measured by real-time PCR. Results: Neutrophils were the dominant source of MMP-8 and MMP-9. Upon moderate stimulation with IL-8, the neutrophil release of MMP-9 was higher in the SA patients compared with controls (p,0.05). In PBMC, the TIMP-1 and MMP-9 mRNA expression was higher in SA patients compared with controls, p,0.01 and 0.05, respectively. There were no differences in plasma levels between patients and controls except for TIMP-2, which was lower in patients, p,0.01. Conclusion: Measurements of MMPs and TIMPs in plasma may be of limited use. Despite similar plasma levels in SA patients and controls, the leukocyte-derived MMP-9 and TIMP-1 are significantly altered in patients. The findings indicate that th

Corrigendum to “Viewpoint: Rigorous monitoring is necessary to guide food system transformation in the countdown to the 2030 global goals” [Food Policy 104 (2021) 100784]

We regret that the original Fig. 3 was based on a spreadsheet later discovered to have an aggregation error, overestimating the number of food system workers. A corrected Fig. 3 has replaced the erroneous figure. We are deeply grateful to Natalia Piedrahita of FAO for her careful attention and discovery of the error