Development of big and small and medium-sized enterprises in global economy

The objective of this article is to present development of big and small and medium sized enterprises in global economy and to reveal some tendencies and perspectives (for example creation of a global system of big, small and medium-sized enterprises (Global Bigness-SME system – GloBSMEsS). The formation of GloBSMEsS is an objective process, brought about by globalization, transnationalization and international economic integration. It is represented by the transnational corporations and banks. Goods, financial funds, patents, know-how and other economic resources can be tapped on the virtual territory of these international economic complexes. This in turn offers unlimited opportunities to choose from all possible combinations of the entrepreneurial success

Investigation of as-cast light alloys by selected homogenization techniques with microstructure effects

Publisher Copyright: © Springer Nature Switzerland AG 2019.In the present contribution, upgrading the findings of previous works, [1, 2], new models are proposed for evaluation of effective mechanical properties of light alloys regarded as multiphase composites. These models are aimed to improve the mechanical properties predictions of two groups light alloys: die cast Mg alloys AZ and metal foams with closed cells. The presented models are variants of Mean Field Homogenization (MFH) approach and Differential Homogenization Method, (DHM), both accounting for microstructure size effects. They are appropriate for composite structures where the content of non- matrix phases is predominant. The microstructure - properties relationships for AZ Mg alloy with Continuous (C) and Discontinuous (D) intermetallic phase precipitations are investigated applying MFH and DHM approaches. The basic distinction between cases (C) and (D) consists of different arrangement and volume fraction of harder intermetallic phase Mg17Al12. The type of the microstructure observed depends mainly on the applied cooling regime and chemical composition of the alloy. The elastic-plastic properties predictions for both types of microstructure topology are compared and discussed. The elastic behavior of foams with closed pores is simulated applying DHM, where the size sensitive variant of Mori-Tanaka scheme is used as a basic ‘dilute case’ procedure. The method is developed to closed form solutions of corresponding system of differential equations. The results obtained by means of the size-sensitive DHM are compared with experimental data for aluminium and glass foams taken from the literature.Acknowledgements This research is carrying out in the frame of KMM-VIN - European Virtual Institute. The financial support of BG FSI through the grant DH 07/17/2016 ‘New approach for structure and properties design of amorphous and nanostructured metallic foams’ is gratefully acknowledged.Peer reviewe