Université Nantes Angers Le Mans

About: Université Nantes Angers Le Mans is a education organization based out in Nantes, France. It is known for research contribution in the topics: Geology & Population. The organization has 434 authors who have published 249 publications receiving 7208 citations. The organization is also known as: PRES Universite Nantes Angers Le Mans.

Wave dynamics analysis at the intake of a turbocharged engine: concept proposal of a new active inlet charge air duct for low-speed tuning and high-speed permeability

Abstract: The unsteady-state gas dynamics at the intake of a turbocharged engine were analyzed. The objective is to tune the intake line to low operating speeds where the exhaust gases lack the enthalpy needed to operate the turbocharger at rated speeds and to provide the boost pressure needed. The proposed methodology compensates for the lack of boost pressure by benefiting from the existing wave action at the intake. Zero-dimensional acoustic modelling is first used to investigate the geometrical parameters which have the most influence on low-end acoustic tuning. Impedance bench and electrically driven engine tests complete the study and compare different intake configurations and two geometries of charge air coolers: an air-to-air charge air cooler and a water-cooled charge air cooler. Optimal intake configurations were found for low-end torque considerations as well as high-speed operation where a reduction in the pressure losses is most important. The findings were validated and established on an engine test bench with torque gain at different rotational speeds of the engine. The study led to the proposal of an active charge air duct which enables a solution to be found for the low-end torque where acoustic tuning is favored and for high-speed operation where the boost pressure is readily available. The acoustic response of this part was compared with the reference solution, and conclusions and possible topics for future work were obtained from the analysis.

Thermal mechanical characterization of copolyester for additive manufacturing using FDM

Abstract: The main purpose of this study is to highlight the thermal and mechanical characterization of printed copolyester-based polymer. The variety of benefits of this material, such as its food contact compliance and important mechanical properties, have proved to be effective in huge field of applications, including medical sector and packaging uses. However, it has not received much attention for 3D printing processes. As the printing temperature is a key parameter of fused deposition modeling (FDM) process, the present study is started by analyzing its effect on the mechanical properties of printed copolyester under tensile loading. Indeed, the determination of temperature optimal values to print this material with FDM process is done based on tensile properties, including tensile strength, Young's modulus, ultimate tensile and yield strength, ductility and fracture toughness. The fracture properties of printed copolyester are also discussed using “scanning electron microscopy” (SEM). The results indicate a strong effect of the extrusion temperature on tensile properties. In addition, the analysis of copolyester sample microstructure reveals several damage mechanisms within the printed parts that reflect different types of wires fracture form subjected to the same tensile loading.

Nature and Specificity of Gestural Disorder in Children with Developmental Coordination Disorder: A Multiple Case Study.

Abstract: Aim: Praxis assessment in children with developmental coordination disorder (DCD) is usually based on tests of adult apraxia, by comparing across types of gestures and input modalities. However, the cognitive models of adult praxis processing are rarely used in a comprehensive and critical interpretation. These models generally involve two systems: a conceptual system and a production system. Heterogeneity of deficits is consistently reported in DCD, involving other cognitive skills such as executive or visual-perceptual and visuospatial functions. Surprisingly, few researches examined the impact of these functions in gestural production. Our study aimed at discussing the nature and specificity of the gestural deficit in DCD using a multiple case study approach. Method: Tasks were selected and adapted from protocols proposed in adult apraxia, in order to enable a comprehensive assessment of gestures. This included conceptual tasks (knowledge about tool functions and actions; recognition of gestures), representational (transitive, intransitive), and non-representational gestures (imitation of meaningless postures). We realised an additional assessment of constructional abilities and other cognitive domains (executive functions, visual-perceptual and visuospatial functions). Data from 27 patients diagnosed with DCD were collected. Neuropsychological profiles were classified using an inferential clinical analysis based on the modified t-test, by comparison with 100 typically developing children divided into five age groups (from 7 to 13 years old). Results: Among the 27 DCD patients, we first classified profiles that are characterised by impairment in tasks assessing perceptual visual or visuospatial skills (n = 8). Patients with a weakness in executive functions (n = 6) were then identified, followed by those with an impaired performance in conceptual knowledge tasks (n = 4). Among the 9 remaining patients, 6 could be classified as having a visual spatial/visual constructional dyspraxia. Gestural production deficits were variable between and within profiles. Discussion: This study confirmed the heterogeneity of gestural production deficit among children with a diagnosis of DCD, at both intra- and inter-individual levels. The contribution of other cognitive deficits in most of the profiles allows discussing the specificity of gestural difficulties. This argues in favour of the necessity to distinguish gestural problems with other deficits made apparent through gesture.