From Decadence to Teurgy

The article focuses on comparative analysis of aesthetic philosophical concepts of Czech and Russian symbolism at the end of 19th and the beginning of 20th century. The attention is predominantly paid to interpretation of selected theoretical studies and essayistic work by Czech and Russian followers of dec­adent-symbolist and symbolist aesthetics. In this article we are showing inner connections in genesis of aesthetic-philosophical system, which, in context of East and West-Slavonic literatures, represents gradual heading from decadent-symbolic aesthetics to broader trans-cultural syntheses.В статье на основе сравнительного анализа рассматриваются эстетическо-философские концепции русского и чешского символизмов конца 19 - начала 20 столетия

Comparison of particle placement schemes for discrete element models

The estimation of uncertainties in probabilistic structural analysis may improve if the spatial variability concept is roperly introduced. The presented paper addresses various discrete particle placement choices and schemes for discrete particle models such that the governing realization of random fields for spatially variable material properties is correlated to a particular structural discretization (i.e. radius and placement of particles) in a discrete framework. Although some discrete element models already mimic microstructural effects of concrete very well, when compared to the continuum framework, there are still reasons for introducing higher order spatial variability, such as the statistical size effect that cannot be captured numerically without introducing spatial variability in the material property fields with an appropriately chosen auto-correlation length. By introducing the newly developed spatial variability package, classical experiments for concrete may be more realistically reproduced and associated statistical features discussed, also in terms of particular particle placement schemes, observed scattering and physical reference

DFAs and PFAs with Long Shortest Synchronizing Word Length

It was conjectured by \v{C}ern\'y in 1964, that a synchronizing DFA on $n$ states always has a shortest synchronizing word of length at most $(n-1)^2$, and he gave a sequence of DFAs for which this bound is reached. Until now a full analysis of all DFAs reaching this bound was only given for $n \leq 4$, and with bounds on the number of symbols for $n \leq 10$. Here we give the full analysis for $n \leq 6$, without bounds on the number of symbols. For PFAs the bound is much higher. For $n \leq 6$ we do a similar analysis as for DFAs and find the maximal shortest synchronizing word lengths, exceeding $(n-1)^2$ for $n =4,5,6$. For arbitrary n we give a construction of a PFA on three symbols with exponential shortest synchronizing word length, giving significantly better bounds than earlier exponential constructions. We give a transformation of this PFA to a PFA on two symbols keeping exponential shortest synchronizing word length, yielding a better bound than applying a similar known transformation.Comment: 16 pages, 2 figures source code adde

Tertiary creep in concrete

Time dependent concrete fracture is simulated using a rate type creep model coupled with a discrete concrete model. The numerical study uses experimental data, of various tests, three point bending, relaxation, tensile, performed on concrete. This contribution demonstrates the capability of the model to capture the time dependent fracture behavior of concrete, and predicts the critical time of failure

Calibration and comparison of concrete models with respect to experimental data

At the beginning of the 21st century, civil engineers more than ever face the often-contradictory demands for designing larger, safer and more durable structures at a lower cost and in shorter time. Concrete has been used for many centuries as a safe and durable building material. Two of the main advantages of concrete are its high compressive strength and that it can be cast on the construction site into a variety of shapes and sizes. Many different constitutive models have been developed to fulfill the above mentioned requirements and describe/predict the behavior and failure of concrete. The never ending challenge for engineers is to choose and set up the appropriate material model for the modeling of structures or structural elements. Therefore, the primary objective of the present research is to calibrate, validate and compare different constitutive models with respect to an extensive set of experimental data. Depending on the application and availability of data, the expected prediction quality of the available models may vary significantly. The studied material models include the microplane models M4 and M7, the damage plasticity models available in commercial (ATENA) or open source (OOFEM) finite element codes, e.g. the Grassl-Jirasek material model. Moreover, the Lattice-Discrete-Particle- Model (LDPM), implemented in the solver MARS, is utilized. We present a comparison of these models with regard to the number of input parameters, their physical meaning, the ease of calibration and their predictive capabilities by utilizing a large set of experimental data derived from specimens, cast from the same batch. All models are calibrated using three mean value nominal stress-strain curves obtained from a notched three-point bending, uniaxial compression and compression under passive confinement test. The calibrated numerical models are then used to predict the results of the remaining experiments, i.e. 3-point bending tests of 4 sizes with various notch depths, splitting tests of 5 sizes, direct tensions tests and torsion tests. These data then serve to assess the prediction quality of the models