Agricultural holdings: hindsight and foresight

In France, the concept of the agricultural holding is a result of a lengthy social construction in which the stages in classification and statistical work have proceeded in tune with the major political struggles and social debates of the 19th and 20th centuries. Some people argue that the “ agricultural holding ” is now just a term revived from the past for the modern “ agricultural enterprise ”. Sociologists and economists therefore need to reconsider the significance and relevance of this concept. The diversity of the ways of practising agricultural activities encountered in French households shows that the economic and social realities referred to in this concept are far too varied for its use in defining a productive sector having an institutional existence. Neither can it be used to demark the social groups that will be entitled to benefit from the support measures of agricul-tural and rural development policies. As a basic statistical unit, however the concept of the agricultural holding can provide a com-mon basic unit for measuring agricultural activity, and the land used for this activity, thereby permitting the integration of results concerning the different functions of agricultural activity (production, natural resource management, land use, socio-economic cohesion, etc.). From this angle, the statistical notion of the agricultural holding as presently defined is of increasing interest for the management of new agricultural and rural policies and for social sciences research.Knowledge, agricultural statistics,agricultural holding,history of concepts, multifunctionality

Existence result for stationary compressible fluids and asymptotic behavior in thin films

In this paper, we are first interested in the compressible Navier-Stokes equations with densitydependent viscosities in bounded domains with on-homogeneous Dirichlet conditions. We study the wellposedness of such models with non-constant coefficients in non-stationary and stationary cases. We apply the last result in thin domains context, justifying the compressible Reynolds equations

A simple model for the dynamics of contact lines freezing on a cold substrate

International audienceStarting from de Gennes model of contact line dynamics, we develop a simple, analytical, description of a four phase contact line, at which a liquid advances on a cold substrate (of infinite therml conductivity) and at the same time freezes on the solid. The key idea consists in a subtle balance between thermical and hydrodynamical divergences at contact line, heat produced by dissipation in the liquid phase limitating the solid growth. We calculate the apparent liquid contact angle and its equivalent for the solid phase as a function of the contact line velocity U and the other parameters involved, in the limit of small angles. We show that the arrest condition (U=0) implies a divergence of these angles, that are presumably reaching 90°, while the liquid film thickness vanishes, which is reminiscent of previous works of Sonin et al in the 90's. Remarkably, at low contact line velocity, we show that a stick-slip behaviour is to be expected, which has been recently observed experimentally. The temperature dependance of the critical velocity differs from what is found in recent experiments, but this model is to our opinion a necessary first step to understand these complex behaviours

Experimental study of locally loaded timber in compression perpendicular to the grain

Since the test method for compression strength perpendicular to the grain was changed from a partial area to a full area loading test, strength values for softwood in EN 338 were significantly reduced. Consequently, a change in Eurocode 5 was necessary to ensure an equivalent resistance level in compression perpendicular to the grain. Experimental results are presented with wood in compression perpendicular to the grain. A numerical model is also presented. This model was used to establish a rule of calculation proposed at the P21A-Committee of the technical and construction equipment standardization office (BNTEC)

Thermomechanical fatigue of stainless steels for automotive exhaust systems

National audienceStainless steel grades are now widely used for automotive exhaust systems, in order to increase their durability. Indeed, the exhaust systems are subjected to ever more severe conditions and they include high technology components such as manifolds, catalytic converters and particle filters. This evolution is a direct consequence of the worldwide effort to decrease automotive pollutant emissions in accordance with the new environmental regulations. This paper deals with the thermomechanical fatigue (TMF) of stainless steels at high temperature, specially behaviour and damage models, and with the recent progress in the development TMF fatigue design tools using FEA related to the design of stainless steel exhaust manifolds. A numerical method is proposed for the design and the lifetime prediction of stainless steel exhaust manifold under a thermal fatigue load. It includes the modeling of manifolds submitted to the thermal cycle reproduced from motor bench tests. The identification of the constitutive law, in particular the elasto-viscoplastic model, for a wide range of temperatures, provides the most realistic stress-strain response of the structure. Finally, a dedicated damage criterion is proposed on the basis of the maximal temperature and plastic strain amplitude reached during a thermal cycle (modified-Taira model). Identification of a more general damage model on the basis of TMF tests is also discussed

La transdisciplinarite comme approche innovante de recherche action; le cas du projet syprobio

L’agriculture biologique et le commerce équitable en Afrique de l’Ouest centrés autour du coton, introduits depuis 1999, ont démontré un vrai potentiel d’augmenter les revenus et d'améliorer la sécurité alimentaire des petits productrices et producteurs. Actuellement, plus de 16'000 producteurs produisent le coton et d’autres cultures vivrières dans leurs systèmes de production en bio dans la sous-région. La diversification de ces cultures biologiques dans la rotation ou la combinaison de ces cultures avec celles d'arbres (agroforesterie) et de l’élevage visent à protéger la productivité en dépit des changements anticipés des conditions climatiques. A travers l'amélioration de la fertilité des sols et la diversification des systèmes de production, l'agriculture biologique a également un potentiel reconnu de contribuer à l'adaptation au changement climatique

An Empirical Assessment of Bellon's Clone Benchmark

Context: Clone benchmarks are essential to the assessment and improvement of clone detection tools and algorithms. Among existing benchmarks, Bellon’s benchmark is widely used by the research community. However, a serious threat to the validity of this benchmark is that reference clones it contains have been manually validated by Bellon alone. Other persons may disagree with Bellon’s judgment. Ob-jective: In this paper, we perform an empirical assessment of Bellon’s benchmark. Method: We seek the opinion of eighteen participants on a subset of Bellon’s benchmark to determine if researchers should trust the reference clones it contains. Results: Our experiment shows that a significant amount of the reference clones are debatable, and this phe-nomenon can introduce noise in results obtained using this benchmark

SYPROBIO: Driving farmer-led innovation platforms to address food security, poverty alleviation and resilience to climate change in West African cotton communities

The social problem of food insecurity and the challenge for farmers in adapting successfully to climate change in West African societies build the framework and scope of our research for development (R4D). It is addressed through a project called Syprobio, operating in Mali, Burkina Faso and Benin. Elected farmers, representing 2000–3000 organic farmers, are conducting on-farm research and cooperating with 40–50 researchers and technicians in testing 27 innovative practices by forming innovation platforms. Soil fertility, seed improvement, pest management, agronomy and socio-economics are the main themes. The innovations being tested are meant to improve food security and climate change adaptation. The main R4D methods used are transdisciplinarity, actor-network theory (Latour 2005), focus-group discussions and decentralised action-research hubs. The innovation, the testing farmers and the researcher build an actor network. After two years, all ten circles of concerted actors (CAC) are productive and, in 2013, they started the second round of testing their selected innovations. The main concern of the farmers is the low soil fertility. Both farmers and researchers learn mutually, as well as the technicians from the farmer organisations. The creativity, determination and curiosity of the self-organised farmer groups, embedded in a supportive research network and exciting value chains, allow fast and effective identification of innovations to be tested and implemented. It is recommended to further invest in better alignment at national level of farmer needs, research methods of national agricultural research institutes and universities, and policies in order to create functional institutions