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The purpose of this study is to understand more of online anonymity in the global file sharing community in the context of social norms and copyright law. The study describes the respondents in terms of use of VPN or similar service related to age, gender, geographical location, as well as analysing the correlation with file sharing frequencies.

This study is to a large extent descriptively collecting data through a web‐based survey. This was carried out in collaboration with the BitTorrent tracker The Pirate Bay (TPB), allowing the authors to link the survey from the main logo of their site. In 72 hours the authors received over 75,000 responses, which gives the opportunity to compare use of anonymity services with factors of age, geographical region, file sharing frequency, etc.

Overall, 17.8 per cent of the respondents use a VPN or similar service (free or paid). A core of high frequency uploaders is more inclined to use VPN or similar services than the average file sharer. Online anonymity practices in the file sharing community are depending on how legal and social norms correlate (more enforcement means more anonymity).

The web‐based survey was in English and mainly attracted visitors on The Pirate Bays' web page. This means that it is likely that those who do not have the language skills necessary were excluded from the survey.

This study adds to the knowledge of anonymity practices online in terms of traceability and identification. This means that it shows some of the conditions for legal enforcement in a digital environment.

This study adds to the knowledge of how the Internet is changing in terms of a polarization between stronger means of legally enforced identification and a growing awareness of how to be more untraceable.

The scale of the survey, with over 75,000 respondents from most parts of the world, has likely not been seen before on this topic. The descriptive study of anonymity practices in the global file sharing community is therefore likely unique.

The purpose of this paper is to evaluate the efficiency of the fast multipole boundary element method (FMBEM) in the analysis of stress and effective properties of 3D linear elastic structures with cavities. In particular, a comparison between the FMBEM and the finite element method (FEM) is performed in terms of accuracy, model size and computation time.

The developed FMBEM uses eight-node Serendipity boundary elements with numerical integration based on the adaptive subdivision of elements. Multipole and local expansions and translations involve solid harmonics. The proposed model is used to analyse a solid body with two interacting spherical cavities, and to predict the homogenized response of a porous material under linear displacement boundary condition. The FEM results are generated in commercial codes Ansys and MSC Patran/Nastran, and the results are compared in terms of accuracy, model size and execution time. Analytical solutions available in the literature are also considered.

FMBEM and FEM approximate the geometry with similar accuracy and provide similar results. However, FMBEM requires a model size that is smaller by an order of magnitude in terms of the number of degrees of freedom. The problems under consideration can be solved by using FMBEM within the time comparable to the FEM with an iterative solver.

The present results are limited to linear elasticity.

This work is a step towards a comprehensive efficiency evaluation of the FMBEM applied to selected problems of micromechanics, by comparison with the commercial FEM codes.