No abstract

Yam (Dioscorea spp.) is a tuber crop grown for food security, income generation, and traditional medicine. This crop has a high cultural value for some of the groups growing it. Most of the production comes from West Africa where the increased demand has been covered by enlarging cultivated surfaces while the mean yield remained around 10 t tuber ha−1. In West Africa, yam is traditionally cultivated without input as the first crop after a long-term fallow as it is considered to require a high soil fertility. African soils, however, are being more and more degraded. The aims of this review were to show the importance of soil fertility for yam, discuss barriers that might limit the adoption of integrated soil fertility management (ISFM) in yam-based systems in West Africa, present the concept of innovation platforms (IPs) as a tool to foster collaboration between actors for designing innovations in yam-based systems and provide recommendations for future research. This review shows that the development of sustainable, feasible, and acceptable soil management innovations for yam requires research to be conducted in interdisciplinary teams including natural and social sciences and in a transdisciplinary manner involving relevant actors from the problem definition, to the co-design of soil management innovations, the evaluation of research results, their communication and their implementation. Finally, this research should be conducted in diverse biophysical and socio-economic settings to develop generic rules on soil/plant relationships in yam as affected by soil management and on how to adjust the innovation supply to specific contexts.

Third body load carrying capacity noted with different materials under different kinematic conditions have been observed under fretting conditions. Tests run in the same machine with steel on steel, and chalk on glass, have shown similar particle shape and shape changes and similar particle motion. Observations show that third bodies formed with particles govern wear.

A three-dimensional model of axisymmetric moving solids submitted to nonaxisymmetric transient heat flux conditions is presented in this paper. Temperature fields are obtained using a new hybrid FFT-FEM method that combines Fourier transform techniques and finite element method. A fast Fourier form algorithm is used which leads to inexpensive computer time. Validation tests are presented. Efficiency of the method is demonstrated.