Modèles d’intégration et pratiques langagières

Usage du français, langues de France, langues de migrants, “langue des banlieues”, enseignement des langues, plurilinguisme… : les questions relatives aux pratiques linguistiques réelles sont nombreuses et soulèvent des débats qui agitent l’actualité. Pour pouvoir y répondre, il est nécessaire de connaître la situation de ces pratiques dans leur ensemble et de s’appuyer sur des données scientifiques

different numerical approaches for the analysis of a single screw expander

Abstract Positive displacement machines (e.g. scroll, twin screw, reciprocating, etc.) are proven to be suitable as expanders for organic Rankine cycle (ORC) applications, especially in the medium to low power range. However, in order to increase their performance, detailed simulation models are required to optimize the design and reduce the internal losses. In recent years, computational fluid dynamics (CFD) has been applied for the design and analysis of positive displacement machines (both compressors and expanders) with numerous challenges due to the dynamics of the expansion (or compression) process and deforming working chambers. The majority of the studies reported in literature focused on scroll, twin screw and reciprocating machines. Furthermore, the limitation of such methodologies to be applied directly to complex multi-rotor machines has been highlighted in literature. In this paper, a single screw expander (SSE) is used as benchmark to evaluate the applicability of different grid generation methodologies (dynamic remeshing and Chimera strategy overlapping grid), in terms of computational resources required, accuracy of the results and limitations. Although, the low-order models have been applied to single screw machines, there is still a lack of CFD analyses due to the particular complexity of the machine geometry and of its working principle. The calculations have been performed with air to reduce the complexity of the problem. to the main results are two folds: (i) the assessment of a numerical strategy with respect to the most critical parameters of a dynamic mesh-based simulation and (ii) the comparison of the pressure field and internal flow features obtained by using different numerical approaches

Computational Models for the Analysis of positive displacement machines: Real Gas and Dynamic Mesh

Abstract In recent years, computational fluid dynamics (CFD) has been applied for the design and analysis of positive displacement machines (both compressors and expanders) with numerous challenges due to the dynamics of the compression (or expansion) process and deforming working chambers. The relative motion and in turn, the variation of the gaps during machine operation implies several obstacles for the implementation of reliable CFD models. The majority of the studies reported in literature focused on scroll, twin screw and reciprocating machines. The limitation of the developed methodologies to be applied directly to positive displacement machines with more complex meshing such as that of single-screw has been highlighted in literature. In this paper, a single screw expander is studied by means of (i) a moving mesh technique (dynamic mesh in the Key Frame Remeshing approach) and (ii) a real gas model of a R134a (Peng-Robinson model) implemented in OpenFOAM ®. On the top of that, all the possible techniques that come with the software are investigated in their application to single screw. An useful review of the state of the art CFD with open-source software (OpenFOAM-v1606+ and foam-extend4.0) is therefore carried out. The reliability of CFD model represents indeed the first step on which the design process and further optimization will be based

CFD Approaches Applied To A Single-Screw Expander

Organic Rankine Cycle (ORC) systems rely on the expander performance to generate power output in an efficient manner. Especially in the low power range (below 100 kWe), positive displacement (PD) expanders (e.g. scroll, twin-screw, reciprocating, vane, spool, etc.) result to be cost-effective. However, commercially available PD expanders are still limited and, in many cases, the existing PD compressors are operated in reversed mode by introducing design modifications to sealing, bearings, port sizes, lubrication requirements to increase both their performance and reliability. Computational fluid dynamics (CFD) as a design and analysis tool of positive displacement machine has been proven to be viable. Challenges arise when CFD is applied to PD machines due to the dynamics of the expansion (or compression) process, presence of internal leakages and heat transfer mechanisms, as well as deforming working chambers. Different grid generation methods and solution schemes have been successfully implemented to scroll, twin-screw and reciprocating machines (Rane et al. 2012, Rane et al. 2013). The limitation of such methodologies to be applied directly to complex multi-rotor machines has been highlighted by Rane et al. (Rane at al. 2012). In this paper, a single-screw expander is used as benchmark to evaluate different grid generation methodologies (dynamic remeshing and Chimera strategy overlapping grid) and commercial software, in terms of computational resources required, accuracy of the results and limitations. The calculations have been performed with air to reduce the complexity of the problem.     REFERENCES Rane S., Kovacevic A., Kethidi M., “CFD Modeling in Screw Compressors with complex multi rotor configurationsâ€(2012), Int. Compressor Engineering Conference at Purdue Univ. Paper 2141. Rane S., Kovacevic A., Stosic N., Kethidi M., “Grid deformation strategies for CFD analysis of screw compressorsâ€, Int. J. Refrigeration, 36(2013), 1883-1893

Networks of low-power CMOS neuromorphic neurons with robust neuromodulation capabilities for intelligent and adaptable neuromorphic systems

3. Good health and well-being9. Industry, innovation and infrastructur

Gut microbiota severely hampers the efficacy of NAD-lowering therapy in leukemia

: Most cancer cells have high need for nicotinamide adenine dinucleotide (NAD+) to sustain their survival. This led to the development of inhibitors of nicotinamide (NAM) phosphoribosyltransferase (NAMPT), the rate-limiting NAD+ biosynthesis enzyme from NAM. Such inhibitors kill cancer cells in preclinical studies but failed in clinical ones. To identify parameters that could negatively affect the therapeutic efficacy of NAMPT inhibitors and propose therapeutic strategies to circumvent such failure, we performed metabolomics analyses in tumor environment and explored the effect of the interaction between microbiota and cancer cells. Here we show that tumor environment enriched in vitamin B3 (NAM) or nicotinic acid (NA) significantly lowers the anti-tumor efficacy of APO866, a prototypic NAMPT inhibitor. Additionally, bacteria (from the gut, or in the medium) can convert NAM into NA and thus fuel an alternative NAD synthesis pathway through NA. This leads to the rescue from NAD depletion, prevents reactive oxygen species production, preserves mitochondrial integrity, blunts ATP depletion, and protects cancer cells from death.Our data in an in vivo preclinical model reveal that antibiotic therapy down-modulating gut microbiota can restore the anti-cancer efficacy of APO866. Alternatively, NAphosphoribosyltransferase inhibition may restore anti-cancer activity of NAMPT inhibitors in the presence of gut microbiota and of NAM in the diet

Elbow Joint Loads during Simulated Activities of Daily Living:Implications for Formulating Recommendations after Total Elbow Arthroplasty.

Background: Overloading of the elbow joint prosthesis following total elbow arthroplasty can lead to implant failure. Joint moments during daily activities are not well-contextualized for a prosthesis' failure limits and the effect of the current postoperative instruction on elbow joint loading is unclear. This study investigates the difference in elbow joint moments between simulated daily tasks and between flexion-extension, pronation-supination, varus-valgus movement directions. Additionally, the effect of the current postoperative instruction on elbow joint load is examined.Methods: Nine healthy participants (age 45.8 ± 17 years, 3 males) performed eight tasks; driving a car, opening a door, rising from chair, lifting, sliding, combing hair, drinking, emptying cup, without and with the instruction "not lifting more than 1 kg". Upper limb kinematics and hand contact forces were measured. Elbow joint angles and net moments were analyzed using inverse dynamic analysis, where the net moments are estimated from movement data and external forces.Results: Peak elbow joint moments differed significantly between tasks (p &lt; 0.01) and movement directions (p &lt; 0.01). The most and least demanding tasks were, rising from a chair (13.4 Nm extension, 5.0 Nm supination, 15.2 Nm valgus) and sliding (4.3 Nm flexion, 1.7 Nm supination, 2.6 Nm varus). Net moments were significantly reduced after instruction only in the chair task (p &lt; 0.01).Conclusion: This study analyzed elbow joint moments in different directions during daily tasks. The outcomes question whether postoperative instruction can lead to decreasing elbow loads. Future research might focus on reducing elbow loads in the flexion-extension and varus-valgus directions.<br/

DexROV: Enabling effective dexterous ROV operations in presence of communication latency

Subsea interventions in the oil & gas industry as well as in other domains such as archaeology or geological surveys are demanding and costly activities for which robotic solutions are often deployed in addition or in substitution to human divers - contributing to risks and costs cutting. The operation of ROVs (Remotely Operated Vehicles) nevertheless requires significant off-shore dedicated manpower to handle and operate the robotic platform and the supporting vessel. In order to reduce the footprint of operations, DexROV proposes to implement and evaluate novel operation paradigms with safer, more cost effective and time efficient ROV operations. As a keystone of the proposed approach, manned support will in a large extent be delocalized within an onshore ROV control center, possibly at a large distance from the actual operations, relying on satellite communications. The proposed scheme also makes provision for advanced dexterous manipulation and semi-autonomous capabilities, leveraging human expertise when deemed useful. The outcomes of the project will be integrated and evaluated in a series of tests and evaluation campaigns, culminating with a realistic deep sea (1,300 meters) trial in the Mediterranean sea

Does 18F-Fluorocholine PET/CT add value to positive parathyroid scintigraphy in the presurgical assessment of primary hyperparathyroidism?

IntroductionTo investigate the value of presurgical 18F-FCH PET/CT in detecting additional hyperfunctioning parathyroids despite a positive 99mTc-sestamibi parathyroid scintigraphy in patients with primary hyperparathyroidism (pHPT).MethodsThis is a retrospective study involving patients with pHPT, positive parathyroid scintigraphy performed before 18F-FCH PET/CT, and parathyroid surgery achieved after PET/CT. Imaging procedures were performed according to the EANM practice guidelines. Images were qualitatively interpreted as positive or negative. The number of pathological findings, their topography, and ectopic location were recorded. Histopathology, Miami criterion, and biological follow-up were considered to ensure effective parathyroidectomy confirming the complete excision of all hyperfunctioning glands. The impact of 18F-FCH PET/CT on therapeutic strategy was recorded.Results64/632 scanned pHPT patients (10%) were included in the analysis. According to a per lesion-based analysis, sensitivity, specificity, positive predictive value, and negative predictive value of 99mTc-sestamibi scintigraphy were 82, 95, 87, and 93%, respectively. The same values for 18F-FCH PET/CT were 93, 99, 99, and 97%, respectively. 18F-FCH PET/CT showed a significantly higher global accuracy than 99mTc-sestamibi scintigraphy: 98% (CI: 95–99) vs. 91% (CI: 87–94%). Youden Index was 0.79 and 0.92 for 99mTc-sestamibi scintigraphy and 18F-FCH PET/CT, respectively. Scintigraphy and PET/CT were discordant in 13/64 (20%) patients (49 glands). 18F-FCH PET/CT identified nine pathologic parathyroids not detected by 99mTc-sestamibi scintigraphy in 8 patients (12.5%). Moreover, 18F-FCH PET/CT allowed the reconsideration of false-positive scintigraphic diagnosis (scinti+/PET-) for 8 parathyroids in 7 patients (11%). The 18F-FCH PET/CT influenced the surgical strategy in 7 cases (11% of the study population).ConclusionIn a preoperative setting, 18F-FCH PET/CT seems more accurate and useful than 99mTc-sestamibi scan in pHPT patients with positive scintigraphic results. Positive parathyroid scintigraphy could be not satisfactory before neck surgery particularly in patients with multiglandular disease, suggesting a need to evolve the practice and define new preoperative imaging algorithms including 18F-FCH PET/CT at the fore-front in pHPT patients

Sex-related differences in risk factors, type of treatment received and outcomes in patients with atrial fibrillation and acute stroke: Results from the RAF-study (Early Recurrence and Cerebral Bleeding in Patients with Acute Ischemic Stroke and Atrial Fibrillation)

Introduction: Atrial fibrillation is an independent risk factor of thromboembolism. Women with atrial fibrillation are at a higher overall risk for stroke compared to men with atrial fibrillation. The aim of this study was to evaluate for sex differences in patients with acute stroke and atrial fibrillation, regarding risk factors, treatments received and outcomes. Methods Data were analyzed from the “Recurrence and Cerebral Bleeding in Patients with Acute Ischemic Stroke and Atrial Fibrillation” (RAF-study), a prospective, multicenter, international study including only patients with acute stroke and atrial fibrillation. Patients were followed up for 90 days. Disability was measured by the modified Rankin Scale (0–2 favorable outcome, 3–6 unfavorable outcome). Results: Of the 1029 patients enrolled, 561 were women (54.5%) (p &lt; 0.001) and younger (p &lt; 0.001) compared to men. In patients with known atrial fibrillation, women were less likely to receive oral anticoagulants before index stroke (p = 0.026) and were less likely to receive anticoagulants after stroke (71.3% versus 78.4%, p = 0.01). There was no observed sex difference regarding the time of starting anticoagulant therapy between the two groups (6.4 ± 11.7 days for men versus 6.5 ± 12.4 days for women, p = 0.902). Men presented with more severe strokes at onset (mean NIHSS 9.2 ± 6.9 versus 8.1 ± 7.5, p &lt; 0.001). Within 90 days, 46 (8.2%) recurrent ischemic events (stroke/TIA/systemic embolism) and 19 (3.4%) symptomatic cerebral bleedings were found in women compared to 30 (6.4%) and 18 (3.8%) in men (p = 0.28 and p = 0.74). At 90 days, 57.7% of women were disabled or deceased, compared to 41.1% of the men (p &lt; 0.001). Multivariate analysis did not confirm this significance. Conclusions: Women with atrial fibrillation were less likely to receive oral anticoagulants prior to and after stroke compared to men with atrial fibrillation, and when stroke occurred, regardless of the fact that in our study women were younger and with less severe stroke, outcomes did not differ between the sexes