Considering light-matter interactions in Friedmann equations

The Friedmann equations valid for the transparent universe are modified for the universe with opacity caused by absorption of light by ambient cosmic dust in intergalactic space. The modified equations lead to a cosmological model, in which cosmic opacity produces radiation pressure that counterbalances gravitational forces. The proposed model predicts a cyclic expansion/contraction evolution of the Universe within a limited range of scale factors with no initial singularity. The maximum redshift, at which the contraction of the Universe stops, is ~14-15. The model avoids dark energy and removes some other tensions of the standard cosmological model.Comment: 10 pages, 3 figures. arXiv admin note: substantial text overlap with arXiv:1902.1052

Celulární automat a CML systémy

The main aim of this thesis is the study of cellular automata and discrete dynamical systems on a lattice. Both tools, cellular automata as well as dynamical systems on a lattice are introduced and elementary properties described. The relation between cellular automata and dynamical system on lattice is derived. The main goal of the thesis is also the use of the cellular automata as that mathematical tool of evolution visualization of discrete dynamical systems. The theory of cellular automata is applied to the discrete dynamical systems on a lattice Laplacian type and implemented in Java language.Hlavním cílem práce je studium vztahu celulárních automatů a diskrétních dynamických systémů na mřížce. Oba nástroje, jak celulární automat tak dynamický systém na mřížce, jsou zavedeny a jejich základní vlastnosti popsány. Vztah mezi celulárními automaty a dynamickými systémy na mřížce je podrobně popsán. Hlavním cílem práce je dále použití nástroje celulárního automatu jako matematického vizualizačního prostředku evoluce diskrétních dynamických systémů. Teorie celulárních automatů je použita na dynamické systémy na mřížce Lamplaceova typu a implementována v prostředí Java.470 - Katedra aplikované matematikyvelmi dobř

Izdelava poroznih kovinskih ulitkov

The article deals with the foundry methods of manufacturing porous metal; it is focused on the materials with a regular arrangement of internal cells. Currently. there are many fields dealing with the problem of porous metals by either optimizing the already known technologies, developing new ones or using porous metals. The production of a porous metal with a regular structure of cells and the possibility of its functional usage are the main subjects of this article. Due to their shapes, sizes and distribution of internal pores, cast porous metals exhibit various properties including reduced weight, sufficient strength, an ability to absorb impact energy, a possibility to conduct heat, etc., that allow a wide range of applications in the areas such as construction. transport or power engineering.Članek opisuje livarske metode izdelave poroznih kovin. Osredotoča se na materiale s pravilno urejenostjo notranjih celic. Trenutno se na mnogih področjih ukvarjajo s problemi poroznih kovin, bodisi z optimizacijo že znanih tehnologij, razvojem novih, ali njihovo uporabo. Glavni predmet članka je izdelava poroznih kovin s pravilno strukturo celic in možnostjo njihove uporabe. Porozni ulitki imajo zaradi svoje značilne oblike, velikosti in porazdelitve por različne specifične lastnosti, vključno z manjšo maso, zadovoljivo trdnostjo, sposobnostjo absorpcije udarne energije, prevajanja toplote itd. Vse to omogoča njihovo uporabo na različnih področjih, kot so konstrukcije, transport, inženiring prenosa energije in moči.Web of Science53114113