Comparison of alternative approaches to neural network PID autotuning

In this paper, a scheme for the automatic tuning of PID controllers on-line, with the assistance of trained neural networks, is proposed. The alternative approaches are presented and compared.

“Should we all be on Marx’s side?” Contributions of post-marxist discourse theory to the historiography of communism

Drawing on post-marxist discourse theory inspired by the writings of Ernesto Laclau and Chantal Mouffe, this article puts the case for a literature on communism situated at the crossroads of critical theory, cultural studies and historiography. Specific illustration is provided by the author's own research on British communism and the Spanish Civil War. However, the scope of the article is much broader and it is intended as a contribution to the theoretical discussion of future possibilities for communist history-writing. The article concludes that discourse should be regarded neither as a flat surface of tightly knit signifiers nor as an impenetrable monolith of meaning systems. Rather, it should be seen as an inherently dynamic phenomenon, with its own condensations and dispersions along the historical continuum. In this lies its significance for historians of communism.

Methodological aspects of a mathematical programming model to evaluate soil tillage technologies in a risky environment

In this work we develop a methodology for the economic evaluation of soil tillage technologies, in a risky environment, and to capture the influence of farmer behaviour on his technology choice. The model has short-term activities, that change with the type of year, and long-term activities, in which sets of traction investment activities are included. Although these activities do not change with the type of year, they lead to different availability of resources for each type of year, since the same tractor has different available fieldwork days under different weather conditions. We prove that the model is sensitive to the greater income variability resulting from the use of alternative technologies and to the balance between income and risk, accounting for the probability of occurrence of each state of nature and giving an investment solution that considers the best production plan for each type of year. (c) 2005 Elsevier B.V. All rights reserved.