‘Reindeer Botanist’ and the Onset of Canadian Arctic Ecology (In memory of the 40th anniversary of A. E. Porsild’s passing)

Alf Erling Porsild, a field naturalist by birth and life-long practice was a pioneer, greater than life Canadian Arctic eco-botanist. And that before the term ‘ecology’ became a household name among the Canadian field biologists

Feasibility studies on future phycological research in polar regions

Cyanobacteria and algal communities are essential in the process of initial primary succession following landscape deglaciation. Near the glacial front, a shallow wetland zone is maintained by melting ice. Here, algal mats and crusts quickly develop. The ground in all of these wet habitats is cold due to the close presence of the glacial front and permafrost. Cyanobacteria and algal populations which survive and expand in such extreme cold and unstable environments display special ecological and physiological acclimatization-adaptation characteristics, which enable them to succeed during the initial colonization phase. In this text, it is proposed to use these young microbial ecosystems as feasibility studies for developing the necessary methodology to assess the algal response to climate change. Cyanobacteria and algal communities are the most appropriate model microorganisms for such study because of their global universality, environmental sensitivity, fast reproductive potential and relatively easy experimental manipulation. We propose the microbial studies on three different mutually complementary levels : ・Study of diversity, structure and life strategies of Cyanobacteria and algae participating in the initiation of primary succession. ・Study of primary production, nitrogen fixation and nutrient utilization in natural and nutritionally-manipulated experimental set-ups. ・Study of physiological response of Cyanobacteria and algae to temperature change. The processes of primary succession have been widely studied by Japanese, as well as Czech, scientists in polar regions during recent times. In this paper, we review phycological studies which have been carried out in the Antarctic and the Arctic, and sounded on feasibility studies in this field

Research and implementation of motorcycle simulator controls

The paper is focused on research in the field of motorcycle simulator controls from the rider’s point of view, with a focus on the longitudinal and lateral dynamics of vehicle. The subject of the research is the design and testing of a suitable composition of input signals controlled by the rider and their integration into the virtual scene. The design and testing of the communication interface between the HW simulator and the physical model of the motorcycle is mentioned in the paper as well. Furthermore, the work describes the suitable HMI elements of the motorcycle and their integration options into the simulator system. In conclusion of the article, various variants, and approaches for controlling the developed motorcycle simulator are discussed, including the possibilities of validating the achieved results

Geometrie Poisson-Lieovy T-duality

V této práci se zabýváme geometrií Poisson-Lieovy T-duality. Nejprve zavedeme Lieovy a Courantovy algebroidy a zobecněné metriky na nich. Poté použijeme Diracovy struktury a zobecněné izometrie k formulaci obecné verze Poisson-Lieovy T-duality, neabelovské verze T- duality, známé z teorie strun.In this thesis we study geometry of Poisson-Lie T-duality. We develop the language of Lie and Courant algebroids and study generalized metrics on them. Then we use Dirac structures and generalized isometries to formulate a general version of Poisson-Lie T-duality, a non-abelian version of T-duality, known from string theory.Matematický ústav UKMathematical Institute of Charles UniversityMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Numerical simulation of crack propagation in ceramic composites in 3D

Pevnost materiálů jako je sklo a keramika může být ovlivněná prostředím (koroze pod napětím). Při namáhání mohou poruchy (trhliny) růst subkriticky pod lomovou houževnatostí K_Ic. Cílem této práce bylo vyvinout tři-dimenzionální konečnoprvkový model pro analýzu chování podkritického růstu trhlin v částicových kompozitech na bázi keramiky. K predikci směru růstu trhliny v rámci lineární elastické lomové mechaniky bylo použito kritérium maximálního tangenciálního napětí. Modelovaným materiálem byla nízkoteplotně vypalovaná keramika (LTCC), obsahující částice oxidu hlinitého uložené ve skleněné matrici. Hlavním cílem práce bylo vyvinout 3D model popisující růst trhliny. Závěry z této práce mohou přispět k lepšímu porozumění podkritického šíření trhlin v částicových kompozitech.The strength of materials such as glass and ceramics can be influenced by the environment (stress corrosion). Under applied stress defects (cracks) can grow sub-critically below fracture toughness K_Ic. The aim of this work was to develop a three-dimensional finite-element model to analyze the subcritical crack growth behavior of ceramic-based particulate composites. The maximum tangential stress criterion (MTS) was used to predict the direction of the crack propagation in the framework of linear elastic fracture mechanics. The modeled material was a Low Temperature Co-fired Ceramics (LTCC), containing alumina particles embedded in a glass matrix. The main aim of this work was to develop a 3D model describing the crack growth. Conclusions from this work can contribute to a better understanding of subcritical crack propagation in particle composites.