Computational design and optimization of wind farms using analytical derivatives

This paper presents a multidisciplinary framework for computational design and optimization of coupled offshore wind farm layout and support structure using analytical derivatives. Gradient-based optimization with exact analytical derivatives scales well with large design problems, and it is the preferred approach over gradient-free techniques. We used the second order Larsen model to simulate the wake in the wind farm. Combined with an energy production model and Weibull wind distribution function, the annual energy production of the wind farm is computed. Timoshenko beam elements model the support structure including the soil-structure interaction. Airy’s wave theory with Wheeler stretching is utilized for modeling the wave kinematics and to obtain the hydrodynamic loads using Morison’s equation. Cost models are used to evaluate the levelized cost of energy as the objective function. The design constraints are the support structure buckling, modal-frequency, and stresses. To evaluate the effectiveness of the proposed approach, we performed an optimization of a feasible baseline design consisting of 6 Vestas V80 wind turbines. Compared to the baseline design, our results show that the coupled layout and support structure approach reduces the levelized cost of energy by 1.4%. This efficient computational framework allows the concurrent design of the wind farm layout and support structure with thousands design variables, and it suitable for detailed design of offshore wind farms. © 2019, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved

Models of innovation: Why models of innovation are models, or what work is being done in calling them models?

Models abound in the literature on innovation. They are continuously being invented and succeed one after the other. At the same time, these models are regularly criticized. This article looks at models of innovation and conducts a conceptual analysis of models. To the producers and users of models of innovation, a model has at least five different meanings: conceptualization, narrative, figure, tool, and perspective. This article suggests that the term ‘model’ has both a scientific and a rhetorical function. A ‘model’ is a symbol of scientificity and travels easily between scholars and between the latter and policy-makers. Calling a conceptualization or narrative or tool ‘model’ facilitates its propagation

Selection without replicators: the origin of genes, and the replicator/interactor distinction in etiobiology

Genes are thought to have evolved from long-lived and multiply-interactive molecules in the early stages of the origins of life. However, at that stage there were no replicators, and the distinction between interactors and replicators did not yet apply. Nevertheless, the process of evolution that proceeded from initial autocatalytic hypercycles to full organisms was a Darwinian process of selection of favourable variants. We distinguish therefore between Neo-Darwinian evolution and the related Weismannian and Central Dogma divisions, on the one hand, and the more generic category of Darwinian evolution on the other. We argue that Hull's and Dawkins' replicator/interactor distinction of entities is a sufficient, but not necessary, condition for Darwinian evolution to take place. We conceive the origin of genes as a separation between different types of molecules in a thermodynamic state space, and employ a notion of reproducers.John S. Wilkins, Clem Stanyon, Ian Musgrav