A guideline for modelling relations of embodiment and function in agile development

Abstract In current product development, the increased usage of agile approaches from software development is observable. With these approaches, improved responsiveness of developer teams to the dynamics of today's markets is desired. However, the gain of technical knowledge in these approaches has so far received little support, leading to difficulties in implementation in engineering design projects that deal with physical product aspects. This contribution aims to provide a guideline to gain technical knowledge about physical products in agile processes through the usage of qualitative modelling of embodiment function relations. This guideline is developed by integrating and adapting the Contact and Channel approach into the agile approach Agile Systems Design. It aims at aiding the evolutionary and iterative development in rapid cycles through fractal modelling of qualitative technical knowledge. The guideline is applied in two development projects. It shows potential to support developer teams by providing different aspects of the Contact and Channel approach in different phases of agile projects, depending on the tackled task

Development of a model predictive controller for floating offshore wind turbines

In this work, an Economic Model Predictive Controller for a floating offshore wind turbine is presented. The classical Model Predictive Control for floating offshore wind turbines provides promising results. In addition, research on onshore wind turbines revealed the potential of the economic control method, which can improve the closed-loop behavior and simplify the control design in comparison to the classical version of this control method. The aim of this work is, to develop a novel Economic Model Predictive Controller for a floating offshore wind turbine based on these two research results. A simplified low order model of a floating offshore wind turbine serves as a basis for the controller design. Including the disturbance preview and constraints, the controller computes optimal trajectories for the blade pitch and the generator torque. To apply the control technique to a floating offshore wind turbine two things have to be done: Firstly, the cost function is designed, to fulfill the main objectives of, maximizing the generated power and alleviating the structural fatigues. Secondly, the constraints are integrated into the control problem. After selecting a suitable solver, the controller is discretized and scaled, thus a proper implementation and smooth operation is possible. Afterwards, the successful functioning of the algorithm, a multi-objective optimization is done, to find appropriate weights to adjust the cost function for the required objectives. Finally, the developed controller is tested with realistic wind and wave disturbances. A significant reduction of the standard deviation of the generated power can be shown, while maintaining real time capability. Furthermore, the structural fatigues of the tower and the platform are decreased

Simple Fabrication of an Organic Laser by Microcontact Molding of a Distributed Feedback Grating

Lasing from an organic polymer is demonstrated in a device utilizing a distributed feedback (DFB) grating, manufactured by microcontact molding of CdSe nanocrystals (NCs) directly on top of the emitter layer. Besides the simpler fabrication in comparison with a reference device based on a photolithographically prepared DFB grating in a bottom dielectric layer, a much higher DFB strength for NC-gratings is observed, resulting in reduced lasing threshold and a fourfold differential lasing efficiency