The aim of this article is to provide an empirical test of the model of non-economic transfers by migrants such as values, attitudes, behaviours, lifestyles, transnational social networks, know-how, skills and knowledge. The first part of the article discusses the current state of Polish society, identifies the direc-tion of social change in Poland since 1989 and analyses the mutual dependency between social change and migration. The second section offers the analytical model and describes how existing empirical data from official statistics and research reports as well as the author’s own research projects have been analysed. The crucial element of the model is the notion of ‘closure’, defined as any factor that makes the migrants’ non-economic transfers difficult or impossible. Within each of the three categories of closure – socio-economic, cultural and psycho-social – more specific barriers to non-economic trans-fers are tested, e.g., lack of cohesive policy towards return migrants, social narratives on migration or ‘homecomer syndrome’. The analysis leads to the conclusion that, however difficult the measurement of the impact of return migration on social change at this stage, return migrants’ transfers are accelerating the process of social change in Poland towards the model of well-developed, post-modern Western societies, whereas closures impede this process.

This study was conducted under the 4R-UAV project. The project is funded by the Latvian Council of Science with the goal of creating an innovative, aerodynamically improved, environmentally friendly, zero waste, and zero emission UAV. For the Circular Aviation 4R (Reduce, Recycle, Reuse, Redesign) concept, this paper covers two Rs (Reduce and Redesign) aspects of the 4R-UAV project. Topology optimization of structures has gained enormous potential with the advances in additive manufacturing techniques. However, it is still challenging when it comes to conventional manufacturing. Aircraft/UAV wings are conventionally hollow structures and leave almost little or no space for further material removal. It becomes even more complicated when conventional manufacturing limitations are further imposed. Nevertheless, topology optimization is indeed an excellent way of reducing the mass of the structures by keeping the mechanical strength intact. This computational study attempts to implement topology optimization on a small-scale aircraft aluminum alloy wing as well as on a carbon composite UAV wing. In order to ensure the feasibility of not only additive manufacturing but also conventional manufacturing, controlled/limited topology optimization was applied only to the ribs of the wings. It was found that topology optimized wing ribs (aluminum and carbon composite) demonstrated a 20% mass reduction while up to 10% overall mass reduction of the wings was achieved. Moreover, after the topology optimization, the wings demonstrated improved mechanical characteristics and factor of safety. The knowledge learned from this study will be implemented for the topology optimization of the future small-scale 4R-UAV wings which will be mainly manufactured using additive manufacturing.

The aim of the article is to analyse the spread and diffusion of socio-economic development in Poland in 2004-2016, while considering spatial aspects. Using the linear ordering method in the non-pattern version, a synthetic development measure for all municipalities in Poland was built based on a set of 77 features illustrating various socio-economic aspects, reduced to 25 features. For the measure constructed in this way, the convergence of the beta and sigma type has been examined, divided into 3 groups of municipalities (rural, urban and urban-rural), as well as in regional division. Using the methods of spatial econometrics, the occurrence of spatial effects was examined, in particular the attention was paid to the relationship between the processes of spreading development and spatial forms of diffusion of development. The analysis also allowed to determine the strength of local impacts of spatial connections between individual municipalities.