Introduction/purpose: Molodtsov introduced the concept of soft sets as a new mathematical tool for dealing with problems containing uncertainties. In the literature, different kinds of operations of soft sets are defined and used in theory and applications. Methods: This study is based on the paper "A New Operation on Soft Sets: Extended Difference of Soft Sets" by Sezgin, Ahmad and Mehmood [Journal of New Theory 27 (2019) 33-42]. Results: In this paper, we define a new operation on soft sets, called extended symmetric difference and investigate its relationship between extended symmetric difference and restricted symmetric difference and some other operations of soft sets. Conclusion: The author believes that the obtained results represent a significant improvement of many known results in the existing literature.

In this paper, tiling a plane with equilateral semi-regular convex polygons is considered, and, that is, tiling with equilateral polygons of the same type. Tiling a plane with semi-regular polygons depends not only on the type of a semi-regular polygon, but also on its interior angles that join at a node. In relation to the interior angles, semi-regular equilateral polygons with the same or different interior angles can be joined in the nodes. Here, we shall first consider tiling a plane with semi-regular equilateral polygons with 2m-sides. The analysis is performed by determining the set of all integer solutions of the corresponding Diophantine equation in the form of , whereare the non-negative integers which are not equal to zero at the same time, and are the interior angles of a semi-regular equilateral polygon from the characteristic angle. It is shown that of all semi-regular equilateral polygons with 2m-sides, a plane can be tiled only with the semi-regular equilateral quadrilaterals and semi-regular equilateral hexagons. Then, the problem of tiling a plane with semi-regular equilateral quadrilaterals is analyzed in detail, and then the one with semi-regular equilateral hexagons. For these semi-regular polygons, all possible solutions of the corresponding Diophantine equations were analyzed and all nodes were determined, and then the problem for different values of characteristic elements was observed. For some of the observed cases of tiling a plane with these semi-regular polygons, some graphical presentations of tiling constructions are also given.

A avaliação de comportamento de tanques acoplados é de grande interesse industrial, por normalmente estarem presentes em várias partes diversos processos, como por exemplo, em empresas petroquímicas, de celulose ou tratamento de água. Este trabalho busca modelar um sistema de tanques em série a partir das medições feitas em uma unidade piloto do curso de engenharia química da UFCG. O projeto é constituído por dois tanques em série, um reservatório de alimentação e uma bomba centrífuga que é responsável pela alimentação do primeiro tanque. Para a modelagem do sistema foram adotadas duas abordagens: a lei de Ohm e a primeira lei da termodinâmica aplicada a sistemas abertos. A partir da análise dos resultados, observa-se a clara aderência dos dados experimentais através de validação estatística.

U višestoljetnom razvoju parlamentarizma i predstavničke demokratije parlamenti su predstavljali ključne institucije borbe za demokratiju i ljudska prava. Uloga parlamenata je posebno značajna u zemljama postsocijalističke tranzicije koje nemaju dugu demokratsku tradiciju. Parlamentarna skupština Bosne i Hercegovine čini centralnu instituciju predstavničke/parlamentarne demokratije u Bosni i Hercegovini. Osobina neposredne povezanosti parlamenta i građana instituciji Parlamentarne skupštine Bosne i Hercegovine daje poseban i veći demokratski značaj od drugih institucija političke vlasti. Iskustva drugih država pokazuju da su za upostavljanje i funkcionisanje demokratskog i uticajnog parlamenta potrebne odgovarajuće društveno-ekonomske, političke i kulturne pretpostavke, kao što su: društvena homogenost u pogledu temeljnih vrijednosti, razvijeno civilno društvo, te odgovarajući stepen konsenzusa i integralnosti unutar paralementarnih stranačkih elita. U kojoj mjeri je Parlamentarna skupština Bosne i Hercegovine učinkovita u ostvarivanju predstavničke i nadzorne funkcije? Kako ostvaruje funkciju legitimnosti i učinkovitosti u donošenju zakona i rješavanju društvenih konflikata? Da li je Parlamentarna skupština Bosne i Hercegovine kao najviši zakonodavni organ stvarni nosilac parlamentarne suverenosti? Kakva su iskustva razvoja parlamentarizma i predstavničke demokratije u postdejtonskom političkom razvoju države Bosne i Hercegovine? To su osnovna pitanja koja su predmet elaboracije u ovom radu. Obzirom da političke institucije oblikuju i političku kulturu, cilj ovog rada je i dopuniti određene prijedloge za izmjenu izbornog zakonodavstva kako bi Parlamentarna skupština Bosne i Hercegovine učinkovitije ostvarivala ustavne nadležnosti i svoju demokratsku funkciju.

The potential re-use of red mud in the building and construction industry has been the subject of research of many scientists. The presented research is a contribution to the potential solution of this environmental issue through the synthesis of potential construction materials based on red mud. A promising way of recycling these secondary raw materials is the synthesis of alkali-activated binders or alkali activated materials. Alkali-activated materials or inorganic binders based on red mud are a new class of materials obtained by activation of inorganic precursors mainly constituted by silica, alumina and low content of calcium oxide. Since red mud contains radioactive elements like 226Ra and 232Th, this may be a problem for its further utilization. The content of naturally occurring radionuclides in manufactured material products with potential application in the building and construction industry is important from the standpoint of radiation protection. Gamma radiation of the primordial radionuclides, 40K and members of the uranium and thorium series, increases the external gamma dose rate. However, more and more precedence is being given to limiting the radiological dose originating from building materials on the population these days. The aim of this research was to investigate the possible influence of alkali activation-polymerization processes on the natural radioactivity of alkali activated materials synthesized by red mud (BOKSIT a. d. Milici, Zvornik, Bosnia and Herzegovina) and their structural properties. This research confirmed that during the polymerization process the natural radioactivity was reduced, and that the process of alkali activation of raw materials has an influence on natural radioactivity of synthesized materials.