Optimal Output Regulation for Square, Over-Actuated and Under-Actuated Linear Systems

This paper considers two different problems in trajectory tracking control for linear systems. First, if the control is not unique which is most input energy efficient. Second, if exact tracking is infeasible which control performs most accurately. These are typical challenges for over-actuated systems and for under-actuated systems, respectively. We formulate both goals as optimal output regulation problems. Then we contribute two new sets of regulator equations to output regulation theory that provide the desired solutions. A thorough study indicates solvability and uniqueness under weak assumptions. E.g., we can always determine the solution of the classical regulator equations that is most input energy efficient. This is of great value if there are infinitely many solutions. We derive our results by a linear quadratic tracking approach and establish a useful link to output regulation theory.Comment: 8 pages, 0 figures, final version to appear in IEEE Transactions on Automatic Contro

Technical efficiency in the Chilean agribusiness sector

The reform-process towards a higher world-market orientation has a long tradition in Chile, with all its strengths and weaknesses. The food processing industry is highly competitive on the worldmarket. The following paper investigates the technical efficiency of the Chilean food processing industry between 2001 and 2007. We used a data-set from the 5,941 of firms in food processing industry. The observations are taken of the 'Annual National Industrial Survey'. The method of stochastic frontier analysis is applied; the heteroscedasticity-model is used in order to analyze the determinants of technical efficiency. We included variables capturing different effects before and after the introduction of a liberalization policy in 2004. Raw materials and labor have to largest impact on the output. We could show that technical efficiency is different in the periods before and after 2004. The region with the highest level of efficiency is the metropolitan region around Santiago de Chile. --Technical Efficiency,Food Processing Industry,Chile

Reduced Order Modelling for the Simulation of Quenches in Superconducting Magnets

This contributions discusses the simulation of magnetothermal effects in superconducting magnets as used in particle accelerators. An iterative coupling scheme using reduced order models between a magnetothermal partial differential model and an electrical lumped-element circuit is demonstrated. The multiphysics, multirate and multiscale problem requires a consistent formulation and framework to tackle the challenging transient effects occurring at both system and device level

Determinants of Economic Growth in Organic Farming: The Case of Bavaria and Baden-Wuerttemberg

The organic sector in Germany has experienced a substantial growth since the beginning of the 1990s until today. During this process of expansion, most organic farms have grown in terms of factor endowment, while others have disappeared or reconverted to conventional agriculture. This paper investigates the potential determinants of farms growth in the organic sector. This paper models potential factors that might have an impact on the economic growth of 332 organic farms in Bavaria and Baden-Wuerttemberg. The econometric model was developed based on ‘Gibrat’s Law’, using a fixed effect method (FE). The results suggest that direct marketing and livestock intensity significantly influence farm growth. In addition, less efficient farms grew faster than more efficient ones. This outcome can be explained by the economic pressure on inefficient firms for adaptation during the growth and survival process.farm-growth, Gibrat’s law, technical efficiency, direct marketing, Farm Management,