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Background: Walking while performing a secondary task (dual-task (DT) walking) increases cognitive workload in young adults. To date, few studies have used neurophysiological measures in combination to subjective measures to assess cognitive workload during a walking task. This combined approach can provide more insights into the amount of cognitive resources in relation with the perceived mental effort involving in a walking task. Research Question: The objective was to examine cognitive workload in young adults during walking conditions varying in complexity. Methods: Twenty-five young adults (mean = 24.4 ± 5.4) performed four conditions: (1) usual walking, (2) simple DT walking, (3) complex DT walking and (4) standing while subtracting. During the walking task, mean speed, cadence, stride time, stride length, and their respective coefficient of variation (CV) were recorded. Cognitive workload will be measured through changes in oxy- and deoxy-hemoglobin (ΔHbO2 and ΔHbR) during walking in the dorsolateral prefrontal cortex (DLPFC) and perceived mental demand score from NASA-TLX questionnaire. Results: In young adults, ΔHbO2 in the DLPFC increased from usual walking to both DT walking conditions and standing while subtracting condition. ΔHbO2 did not differ between the simple and complex DT and between the complex DT and standing while subtracting condition. Perceived mental demand gradually increased with walking task complexity. As expected, all mean values of gait parameters were altered according to task complexity. CV of speed, cadence and stride time were significantly higher during DT walking conditions than during usual walking whereas CV of stride length was only higher during complex DT walking than during usual walking. Significance: Young adults had greater cognitive workload in the two DT walking conditions compared to usual walking. However, only the mental demand score from NASA-TLX questionnaire discriminated simple from complex DT walking. Subjective measure provides complementary information to objective one on changes in cognitive workload during challenging walking tasks in young adults. These results may be useful to improve our understanding of cognitive workload during walking.

11th World Congress for Neurorehabilitation , LYON, FRANCE, 07-/10/2020 - 10/10/2020; Question: Non-pharmacologic treatment such as physical exercise has been proven to have beneficial effects on gait disorders in Parkinson's disease (PD). In Lyon (France), Sirroco rehabilitation program is a novel, collective, multidisciplinary program focused on intensive, high amplitude movements, and loudness of speech for patients with PD. However, the effects of physical exercise on dorsolateral prefrontal cortex (DLPFC) activity in patients with PD is still elusive. The main aim of this pilot study was to assess the effects of the Sirocco program in patients with PD on DLPFC activity on single task (ST) and dual-task (DT) walking. Methods: Fourteen PD patients (mean: 66.9 y.o ± 8.1) completed Sirocco sessions for 5 weeks. Changes in oxyhemoglobin concentration (?HbO2) in the DLPFC were measured using functional Near Infrared Spectroscopy during three walking tasks conditions: (1) ST walking, (2) DT walking while counting forward and (3) DT walking while subtracting. Participants were assessed three times: five weeks before the program (T0); few days before (T1) and one week after the program (T2). Walking performance (mean stride time and cadence) was also recorded using foot-sensors. The gain in performance was calculated by subtracting values at T0 and T1 or at T2 and at T1. Results: Significant differences were observed in ?HbO2 between the three times only for the ST walking: ?HbO2 were significantly higher at T1 than at T0 whereas ?HbO2 was lower in T2 than in T1 (p

WCNR, 11th World Congress for Neurorehabilitation, Lyon, FRANCE, 07-/10/2020 - 11/10/2020; 1.Question: Patients with Parkinson disease (PD) report difficulties walking while performing another task. Dual-task (DT) walking may therefore increase the risk of falls. To date, the effect of DT walking on brain activity is not well understood. The objective of this pilot study was to examine dorsolateral prefrontal cortex activity (DLPFC) during single-task (ST) and DT walking conditions in PD patients. 2.Methods: Thirteen patients with PD (mean age: 66 ± 7 years, 8 men, UPDRS motor score (/108): 23 ± 11, Montreal Cognitive Assessment (MoCA) score: 27 ± 2) and 13 healthy older adults (mean age: 64 ± 7 years, 8 men, MoCA score: 28 ± 3) performed three walking tasks: [1] ST walking, [2] DT walking while counting forward (+1) and [3] DT walking while subtracting (-7). Cortical activity in DLPFC, assessed by changes in oxy-haemoglobin (?HbO2) was measured using functional near infrared spectroscopy (NIRSport). Gait performance (speed, cadence and stride length) was recorded simultaneously using wearables sensors (Gait-Up sensors). 3. Results: In ST walking and DT walking while subtracting conditions, ?HbO2 was higher in patients than in controls (p < 0.05). No significant differences in ?HbO2 were found between ST and the two DT-walking conditions in patients whereas ?HbO2 was significantly higher in DT-walking conditions than in ST walking in controls. As expected, patients had reduced walking speed, cadence and stride length compared to controls, regardless of conditions (p < 0.05). Variability of their cadence increased as the walking task difficulty increased, which is not the case for controls. 4. Conclusion This pilot study suggests that dorsolateral prefrontal cortex plays a major role already during ST walking condition in patients in relatively early stages of PD. This may suggest that patients recruit additional cognitive resources, as a measure of cognitive compensation to perform the ST walking. These findings may have implications for rehabilitation of gait in patients with PD, improving automaticity in simple tasks. Another ongoing study will show the effect of an exercise-based intervention program (SIROCCO program) on DLPFC activity while walking in the same group of patients with PD.

12th World Congress of the International Society of Physical and Rehabilitation Medicine. Paris. 8-12 July 2018, PARIS, FRANCE, 08-/07/2018 - 12/07/2018; Introduction/Background Evidence suggests that gait in complex situation is influenced by executive function in normal ageing. But to our knowledge, no study revealed what measurement is the most appropriate to assess impaired walking in older adults. The objective is to (1) test the feasibility of our protocol and (2) to explore the cognitive load during a simple vs. dual walking task in younger and older adults. Material and method To date, 6 young adults (mean=26.7 years old; SD=4.1) were included in this study. Fifteen young adults and 25 older adults will be included by May 2018. Participants are asked to achieve a walking task including four conditions: (1) normal pace walking, (2) subtracting while standing, (3) walking while subtracting and (4) walking while counting forward. Cognitive load is measured by changes in oxygenated and deoxygenated hemoglobin in dorsolateral prefrontal cortex (fNIRS device) and the NASA-TLX questionnaire completed after each condition. Results fNIRS analyses are in progress. Preliminary results showed that younger adults felt higher cognitive effort in both conditions 2 and 3 compared to condition 1 (NASAscorescondition2 (mean (SD)): 66 (18.7) vs NASAscorecondtion1: 9.5 (6.3), W=?2.2, P=0.03; NASAscorecondition3: 78 (14.6) vs NASAscorecondition1, W=?2.2, P=0.03). No significant differences in speed, cadence and stride length were found between conditions 1, 3 and 4 (P>0.05). No significant differences in subtraction performances were observed between conditions 2 and 3 (P>0.05). Conclusion Higher cognitive load in condition 3 in younger adults confirm that our dual task walking is the most cognitively demanding condition. We expect that our fNIRS results in younger adults will be similar to those observed with NASA-TLX questionnaire. However, discrepancies between those two measures are expected in older adults.

ELECTRIMACS 2017, TOULOUSE, FRANCE, 04-/07/2017 - 06/07/2017; Commercial river ship presents good alternative to road transportation in terms of carbon dioxide emissions but not obviously concerning other pollutants. A solution to reduce fuel consumption and respect future pollutant norms can be to use a combined serial-parallel hybrid architecture. Engines dedicated to road transportation with their depollution systems can be used if high downsizing is performed. This paper investigated this possibility focusing on the management of a such hybrid architecture. A parametric studies is then presented to evaluate the fuel economy of such solution.

Etude hybridation d'un automoteur

Etude de l'hybridation de bateaux fluviaux

Transport Research Arena (TRA) 5th Conference: Transport Solutions from Research to Deployment, PARIS, FRANCE, 14-/04/2014 - 17/04/2014; This paper presents a methodology to optimally design the drivetrain of an Extended Range Electric Vehicle (EREV) according to the use specifications from European mobility surveys. At first the analysis of car uses is carried out, and a process aiming to classify the car use profiles into different clusters is proposed. Clusters that could fit typical EREV use are selected and applied in a sizing methodology to design the battery and the Range Extender (RE). Using a validated simulation software, the proposed method takes into account the range requirements of the car use profile, its energy consumption, realistic driving cycles from European database and battery aging. Combined with a simple Total Cost of Ownership (TCO) model, the most cost effective solution is determined, depending on the performance required. The results show that EREVs might be an interesting solution to consider, as they could lead to a significant TCO reduction (-17%) while offering twice as much range as currently available Battery-only Electric Vehicles (BEVs).

EEVC 2014, European Battery, Hybrid and Fuel Cell Electric Vehicle Congress, BRUXELLE, BELGIQUE, 03-/12/2014 - 05/12/2014; Li-ion based Electric Vehicles (EVs) are able to achieve good dynamic performance with enhanced autonomy range compared to last EVs generations. However, the announced range is often subject to important fluctuations according to the vehicle use and to the weather conditions. In order to improve the vehicle autonomy and ensure a better stability of the performance the vehicle use could be optimized. An advanced optimization requires a deep knowledge of the vehicle behavior and of the consumption influent parameters. This paper describes how a relatively simple model could fulfill these requirements and could present a good starting point for optimization actions such as eco-driving, green routing and auxiliaries' management. The presented model includes in particular an electric circuit based battery model that takes into account the diffusion phenomenon. The global vehicle model is validated using the results of a 60-drivers experiment performed with the EV on a predefined route. The variability of the energy consumption, partly due to the driver behavior, is relatively well predicted by the model and the comparison results allow us to plan favorable perspectives to use the developed model for the optimization purpose.

Définition des cycles de conduites pour les Îhicules aixam.