At Fraunhofer IWES a Modelica Library including all major components needed for load calculations of current offshore wind turbines is developed. The library additionally includes models for external conditions, like wind, soil and waves, and their respective influence on the structures. The library constitutes a large effort in the creation of a highly coupled multiphysics model with Modelica for an industrial project. The results obtained with this library are compared to the results from the IEA Wind Task 23 project OC3 1 (Offshore code comparison collaboration). The OC3 project is an international effort to define a set of loadcases and a reference wind turbine that are used to verify simulation systems on a code-to-code basis. In this paper the status and the implemented theories of the individual models at IWES are explained and verification results are presented and discussed.

The OneWind R Modelica Library 1 [15] for coupled wind turbine loads calculation developed at Fraunhofer IWES uses a structural element based on a modal reduction method to model the motion and deformation of flexible wind turbine rotor blades and tower. The degrees of freedom (DOF) are rigid body motions and modal DOF. The ModalElement model allows the simulation of coupling effects like bend-twist coupling in wind turbine rotor blades and the structural behavior is dependent on the selected eigenmodes. This paper gives an overview about the Modelica implementation of the theory of modal elements, the advantages over other methods (finite-elements), how the ModalElement model is included into the OneWind R Modelica Library, and how it is used for load calculation.

With the rapid increase in the number of e-book readers, researchers have become more and more interested in the factors that impact digital reading, because these factors are not only useful for marketing segmentation, but also important for optimizing marketing campaigns of an e-reader device company and the entire digitalpublishing industry. In this paper, we perform stepwise linear regressions and independent sample t-tests (for differences in means) to determine the key factors in ebook reading behavior, and analyze how these factors affect e-book reading. KEY WORDS: e-books, digital reading, survey data, stepwise linear regression, independent sample t-test LITERATURE REVIEW There has been a variety of research on the topic of digital reading and e-book readership. Perrin (2016) did a descriptive analysis and calculated the sample proportions of e-book readers with different education levels. The analysis of his results shows that college graduates are roughly four times as likely to read e-books compared with those who have not graduated from high school. Huang, Liang & Chiu (2013) considered gender differences in e-book reading. They focused on elementary school students and found that the attitudes toward e-books between boys and girls are not significantly different. Zhang & Ma (2011) studied the correlation between a user's education level and mobile reading behavior in China. They concentrated on a specific user group, college students, and concluded that those with a high

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Permanent magnet machine adopting Halbach array has more sinusoidal air-gap flux density distribution and higher air-gap flux density magnitude. Compared with the equal segmented Halbach array, the fundamental magnitude of air gap flux density can be higher and distortion rate can be lower by reasonably designing each segment width in unequal segmented Halbach array. Thus, in this paper, the permanent magnet machine adopting unequal segmented Halbach array is researched. Firstly, an analytical model is established for PM machine adopting Halbach array to improve the calculation efficiency. This analytical model can be applied to the Halbach array having arbitrary pole pair number, arbitrary number of segments per pole, arbitrary segment width and arbitrary gap width between segments. Further, the calculation results for air gap flux density between analytical model and finite element method are compared to verify the analytical model. In addition, the method to determine each segment width in the unequal segmented Halbach array is proposed firstly in this paper. On this basis, effects of the gap width between segments and each segment width under one pole on air gap flux density are researched. The research conclusions will provide guidance for the design and fabrication of unequal segmented Halbach array.