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Présentation du projet NoiseCapture dans le cadre du séminaire Immersion Sciences 2018, organisé conjointement par l’Académiede Rennes, la région Bretagne et le CNRS.

Le principal objectif de cette présente communication est de déterminer les conséquences de phénomènes complexes tel le couplage de la thermo- et photo-oxydation. Pour cette étude, nous nous sommes penchés sur le cas d'une gaine de polyéthylène chargée de noir de carbone et stabilisée avec un mélange classique d'antioxydants synergiques (Irganox 1010 + Irgafos 168), et ce après un vieillissement naturel d'un quart de siècle dans deux conditions d'ensoleillement distinctes: en présence et en l'absence de soleil (endroit sombre). The main objective of the present communication was to determine the consequences of such a complex thermo-photo-oxidation process in a polyethylene-carbon black sheath, stabilised with a classical synergetic antioxidant mixture (Irganox 1010 + Irgafos 168), after natural ageing during a quarter of century in two distinct sunshine conditions: in a presence and absence of sun (dark location).

On-demand Ride-Hailing services (RHs) now play an increasing role within many cities around the world. RHs might increase traffic congestion, vehicle ownership and access inequalities. RHs pose significant challenges for policymakers, and addressing these issues requires detailed information about RHs use. But research on RHs services, especially in African cities, remains scarce. In this respect, this research presents original data on the use and users of RHs in Kenya’s capital, Nairobi, based on the results of an ad hoc survey designed by the author. This paper provides insights into who the users of RHs are, and their motivations for using RHs. Results show that RHs are extensively used in Nairobi (across all socio-economic groups, on a regular basis and way more for work-related trips than in many Western countries). In Nairobi, where only a minority of urban dweller have access to an individual motorized mode of transport, using RHs is gradually becoming necessary to access urban amenities. Nairobi’s inhabitants are facing a growing RHs dependency, which calls in return to public regulation.

_; This proposal adopts a holistic approach to strategic transport investment by discussing the wider economic impacts (WEIs) analysis method in terms of several dominant and emerging methods. The WEIs analysis goes beyond the effects captured in a standard cost-benefit analysis (CBA). A CBA addresses the market for transport services and infrastructure access but neglects the wider impacts on other markets. These wider impacts usually relate to agglomeration, market power, and the behavioral adaptions of firms and households. The high uncertainty in land use changes indicates that WEIs tend to occur in different forms on multiple spatial scales, varying by place and time. Additionally, some activities, such as education, have no direct market value, but may indirectly contribute to the overall economic output and human capital development in cities and regions. Given that the conventional elasticity methods are not goal oriented, it is important to ensure that the WEIs analysis accounts for the stakeholder-specific costs and benefits. Assuming that it is possible to consider all WEIs through theoretical models, major efforts should focus on establishing and maintaining appropriate methodologies and tools. The social and environmental data needed to address biodiversity issues should also be improved and promoted. Complementary to the WEIs, understanding how the behavior of agents changes in response to the new transport options will help clarify the long-term implications of transportation. This will suggest new strategies (territorial appropriation), approaches/ techniques to feasibility, and ?place-based? interrelations, that is, specific interrelations in places. This last aspect is especially important in the current context of the COVID-19 pandemic, which has affected and will likely change transportation behaviors and transport demand in the dynamic future.

Cette étude est basée sur des gaines de polyéthylène chargées de noir de carbone et exposées durant un quart de siècle au vieillissement naturel. Une partie des échantillons a été soumise à des vieillissements thermo- et photo-oxydatifs, alors que l'autre partie a été préservée à l'ombre. Après vieillissement, les gaines ont été analysées à différentes échelles par: spectromètrie IR, analyses élémentaires, mesure du temps d'induction à l'oxydation, rhéologie à l'état fondu et calorimétrie différentielle à balayage. Our study is based on stabilised polyethylene-carbon black sheaths aged during a quarter of century in natural conditions. One part of the specimens was subjected to photo- and thermo-oxidative ageing, while the other part, was protect again sun expositions. After ageing, the main structural changes at different pertinent scales were determined using conventional laboratory techniques: IR spectrophotometry, ultimate analysis and OIT for molecular changes, rheometry in melt state for macromolecular changes and differential calorimetry for micro-structural changes.

The regeneration of inner-city areas is a global challenge. Inner cities in France certainly have their problems, but the nation also has a good record of successful major urban regeneration projects. We have analysed three of these initiatives to understand what factors contribute to good regeneration outcomes. Urban regeneration can be defined as a holistic approach to revitalise under-used areas of the city. It's commonly associated, however, with the related challenges of gentrification, rising property values, and displacement of low-income groups. And these projects do not always achieve a sense of place.

-; On the 17th, 19th and 23rd of July 2007, a series of local thunderstorms induced flash floods in the upper part of the South Tyne river in Northumberland, a rural area located near the border between England and Scotland. These events led to moderate damages in the villages and losses of livestock in local farms. They were shadowed in comparison to the widespread lowland floods that occurred throughout the UK during the same period but were nevertheless extreme events for the region. One of the affected streams, the Thinhope Burn, has been surveyed by the University of Gloucestershire during recent years. It is an active river from a geomorphological point of view. A survey conducted after the 2007 flood revealed that many of the boulders along the banks of the river, which had been deposited 50 to 100 years before, had been displaced, indicating a high return period for the flood (see EGU abstract EGU2008-A-04713). A complementary survey was conducted in July 2008 with the objective of gathering information on the discharges, the rainfall amounts and the active runoff processes. 14 cross-sections were surveyed, pictures were collected enabling a validation of peak discharge estimates, 5 witnesses were interviewed and additional rainfall data and geomorphological evidence were collected. This survey revealed that the peak discharges exceeded 5 m3/s/km2 in the most affected areas. Unfortunately, no rainfall measurements are available that would enable further analysis, including the computation of runoff rates. Nevertheless, witness accounts and field observations give a good insight into the hydrological processes indicating a significant initial storage capacity of the peat layer covering the affected watersheds. Concerning the boulders, the field observations suggest surprising and unexplained transport processes. Blocks of up to one meter diameter were displaced over short distances and deposited on the river banks without any sign of established debris flow, as if short debris pulses occurred along the river course. This work is conducted within the European research project HYDRATE (Contract GOCE 037024).

Workshop on Numerical Methods for High-Dimensional Problems, Ecole des Ponts ParisTech, Marne-la-Vallee, April 14-18

Workshop on Numerical Methods for High-Dimensional Problems, Ecole des Ponts ParisTech, Marne-la-Vallee, April 14-18

Technical Workshop “Imperial College London / Chair ENPC-STIF”, Marne-La-Vallée, France, Dec. 18th 2015.