Development of Visual Extension Material for a Striga Control Programme in Northern Ghana through Action Research.
Abstract In the last two decades, research has developed techniques to control the parasitic weed Striga sp. (Scrophulariaceae), one of the worst pests in the West African Sahel. Yet, some of the control measures are economically not viable, at least not in the short-run, others cure part of the problem only, while some require changes of the entire farming system. The complexity of the problem demands an integrated control approach with solutions that are flexible enough to match the diversity and variability of the farming systems. A better understanding of the parasite's biology by farmers will encourage them to appreciate the current complex and time-consuming Striga control measures. Such an approach calls for close collaboration between researchers, extensionists and farmers. Through action research, a picture supported group extension programme was developed, which was characterised by a shift from a teaching-centred to a learner-centred extension approach in Northern Ghana. The cost for developing...
Putting it into practise
Emphasis has been made on various control options and their combination in an integrated approach in the previous chapter. In this section, the aspect of how to make use of research findings and on how to assist farmers in reducing the threat by parasitic weeds on their livelihood will be the main emphasis.
Robust solutions of inverse problems in electromagnetic non-destructive evaluation
Non-destructive testing (NDT) is the application of physical measurement technology based on energy interaction with the material and its nonconformities. The material's response is sensed by transducers and sensors which?in most cases?scan the component and document the results in inspection images. However, NDT measures a physically defined quantity or even an intrinsic property. The difference between non-destructive evaluation (NDE) and NDT is in the interpretation of the inspection data. NDE has to discuss the inspection results in terms of quality elements and characteristics which are relevant to describe the fitness of the material for use. In the case of macroscopic defects these are the kind of defect (cracklike, globular) and its size and orientation to the main stress directions; in the case of material property determination the parameters are mainly mechanical properties. Therefore, in NDE one has to solve inverse problems. The solution of inverse problems based on mathematical procedures such as integral equations is a strong developing discipline and most of the articles prepared for this special issue of the journal have the objective of discussing the latest state of the art in that field. However, practical NDE needs robust and quick solutions which are to be applied mainly online. Therefore, we present here inversion procedures based on multiple linear regression algorithms applied to inspection data. We describe the calibration procedure to fit the free parameters of the model functions and give examples of practical applications in industry.