Tuesday, November 22, 2022 at 14:00, new large lecture room
Towards development of new equation of state for squalane
Dr. Aleš Blahut, Instute of Thermomechanics of the CAS
Currently, new fundamental equation of state for squalane is being developed at the Chair of Thermodynamics at the Ruhr University Bochum. One of the prerequisites for such development is a reliable database of thermodynamic properties. In case of liquid densities, majority of recent literature data was acquired with vibrating tube method, which however has certain limitations for measurements of viscous fluids such as squalane. Moreover, in order to provide reliable data, vibrating tube densimeters have to be properly calibrated with reference fluids, ideally in the entire temperature and pressure range of measurements.
The presentation introduces a background of equation-of-state development and focuses on new density measurements of squalane, which were carried out during a research stay at the Chair of Thermodynamics in Bochum using unique single-sinker densimeter with magnetic suspension. Experimental method, new results and several correlations representing experimental densities are presented. Because several squalane samples from the same batch were later investigated with vibrating tube densimeter at the Institute of Thermomechanics in Prague, reliability of vibrating tube method for density measurement of viscous fluids is discussed.
A. Blahut gratefully acknowledges funding within "Support for International Mobility of Researchers of the Institute of Thermomechanics, Czech Academy of Sciences, part II", no. CZ.02.2.69/0.0/0.0/18_053/0017555 of the Ministry of Education, Youth and Sports of the Czech Republic funded from the European Structure and Investment Funds (ESIF).
IMPORTANT GDPR NOTICE: By attending this event you consent that we may take photos from the talk (including the audience) and provide it to the Ministry of Education, Youth and Sports (MEYS). MEYS is the funding provider for the project "Support of international mobility of researchers of the Institute of Thermomechanics of the CAS, part II" and the processor of the provided data.
Tuesday, November 8, 2022 at 10:00, new large lecture room
Modelling of Complex Signals in Nerves
Prof. Jüri Engelbrecht in cooperation with Dr. Kert Tamm and Dr.Tanel Peets
Estonian Academy of Sciences and Department of Cybernetics, School of Science, Tallinn University of Technology
The propagation of signals in nerves is a fundamental physical process needed for understanding cognitive processes and mental phenomena. It involves not only electrical signals (action potential, ion currents) but also mechanical disturbances in nerve fibres and temperature changes. The modelling of dynamic processes in continua (leaving aside particle physics, astrophysics, etc. where relativity of motion is of importance) is based on the conservation of momentum which is usually known as Newton’s Second Law. The thermodynamic effects are modelled by Fourier's law (heat flux is related to temperature gradient) and Joule’s law (heat is related to electric current). Traditional models of nerve signals pay more attention to physiology which helps to explain biological phenomena. In order to explain all the phenomena in nerves, a broader view must be elaborated. According to general principles of complex systems, the first step of the bottom-up modelling needs to identify all the basic elements (basic physical processes) and their interactions with each other (couplings) so that many components are united to generate a whole: an ensemble of waves. A possible mathematical model following these ideas is derived. The governing equations for the components of the ensemble correspond either to the modified classical ones for describing the action potentials or are derived from the laws of physics resulting in a consistent system. The interaction of the components of the ensemble is realized by coupling forces. The numerical simulation has shown that the model can grasp the measured effects. The mathematical model generated by authors  is an attempt aiming to couple all the measurable effects of the signal propagation in nerves into a system and demonstrates the importance of basic sciences in developing plausible models. This is an interdisciplinary approach at the interface of physiology, physics, and mathematics but it can be said that physics shapes signals in nerves . The ideas are also supported by philosophical analysis . After establishing the sound backbone of the model, further modification of the modelling involving the influence of the internal structure of a fibre (myelin sheath, the cytoskeleton of the axoplasm, etc.) is possible. An example of the modelling of the myelin sheath demonstrates such a possibility .
 Engelbrecht J., Tamm K., Peets T. (2021) Modelling of Complex Signals in Nerves. Springer, Cham
 J.Engelbrecht, K.Tamm, T.Peets. (2022) Physics shapes signals in nerves. The European Physical Journal Plus, 137, 696
 J.Engelbrecht, K.Tamm, T. Peets. Signals in nerves from the philosophical viewpoint. Proc. Estonian Acad.Sci. (accepted, to appear in 2022)
 K.Tamm, T.Peets, J. Engelbrecht. Mechanical waves in myelinated axons. Biomechanics and Modeling in Mechanobiology - BMMB, 2022 (online available)
Wednesday, October 26, at 14:00, "club"
Velká věda v malém Tibetu (Big science in small Tibet – in Czech)
Dr. Radka Kellnerová
Institute of Thermomechanics, Czech Academy of Sciences
(The lecture will be held in Czech)
Brontosauři v Himálajích pozvali 30 českých vědců do jedné z nejzapadlejších vesnic Malého Tibetu. Měli připravit prázdninovou školu pro děti do 15 let.
Jak to dopadlo? Zvládli vědci takovou výzvu v prostředí, kde stabilní elektřina, signál a pitná voda je pouhý luxus, technické zázemí na míle vzdálené potřebám pro experimenty a kulturní pozadí úplně odlišné od domoviny?
Přijďte si poslechnout povídání Radky Kellnerové o netradičních zážitcích našich výzkumníků v srdci budhismu 3500 metrů vysoko nad mořem.
Tuesday, October 4, at 14:00, new large lecture room
Robocasting: an additive manufacturing technique for fabricating micro-architectured ceramic scaffolds
Dr. Martin Koller
Institute of Thermomechanics, Czech Academy of Sciences
Robocasting is a direct ink writing technique, where the filaments of pseudoplastic ceramic-based dispersions are extruded from a nozzle, following a route prescribed by a CAD model. The ceramic green-body scaffolds are printed layer-by-layer and then sintered to full density. This presentation shows the process of creating the printable inks, i. e. the aqueous dispersion of ceramic powders with highly shear-thinning behavior, based on SiC, Cr2AlC, or Y2O3-stabilized ZrO2 ceramic powders, and the subsequent 3D printing of micro-architectured scaffolds at the Institute of Ceramics and Glass (ICV-CSIC) in Madrid, Spain. The periodic scaffold structure leads to phononic crystal behavior, which has been studied both numerically and experimentally at the Institute of Thermomechanics. The geometry of the scaffolds strongly affects their elastic and acoustic properties; the tetragonal scaffolds have strong elastic anisotropy, which leads to acoustic energy focusing along the direction of the ceramic rods, while the hexagonal scaffolds are in-plane isotropic in the low-frequency limit. At the higher frequencies of several MHz, frequency shear bands are observed, where the acoustic waves do not propagate and their energy is rather dissipated within the scaffold structure. Besides that, novel types of robocast scaffolds, e. g. multi-phase composite scaffolds, or electrically conductive scaffolds reinforced by graphene fillers are shown, highlighting the future prospects in the research of architectured ceramics.
M. Koller gratefully acknowledges funding within "Support for International Mobility of Researchers of the Institute of Thermomechanics, Czech Academy of Sciences, part II", no. CZ.02.2.69/0.0/0.0/18_053/0017555 of the Ministry of Education, Youth and Sports of the Czech Republic funded from the European Structure and Investment Funds (ESIF).
IMPORTANT GDPR NOTICE: By attending this event you consent that we may take photos from the talk (including the audience) and provide it to the Ministry of Education, Youth and Sports (MEYS). MEYS is the funding provider for the project "Support of international mobility of researchers of the Institute of Thermomechanics of the CAS" and the processor of the provided data.
Wednesday, July 27, at 14:00, new large lecture room
Novel Design of a Device for Human Skin Viscoelastic Properties Measurement
Flavie Delouye and Perrine Bégon, students of the Institut National des Sciences Appliquées Centre-Val de Loire, Blois, France,
Supervised by: Zdeněk Převorovský, Daniel Tokar, IT CAS
Human skin has a complex mechanical behavior which can be described as anisotropic and non- linearly viscoelastic. These properties are not well determined but they are of great interest e.g. in cosmetic industry and aesthetic medicine. This talk deals with a novel design of a device which measures the mechanical characteristics of the skin in-vivo, in particular the detailed mechanical design of the prototype device using 3D-printed components. The design of necessary mechanical components deals with a loading base in which are integrated ultrasonic transducers in order to transmit and receive ultrasonic signals propagating in the loaded skin. The loading base is built up with displacement sensor for the purpose of measurement of mechanical loading of the skin. The design of mechanical parts also includes a specific component integrating strain-gauges sensors in order to obtain the stress-strain of the skin tissue. Subsequent to the assembly of the whole device, verification of the mechanical components ensures the coherence of the entire design. The future work will be focused on electrical conception of the device for the motor control, strain-gauges and displacement sensor for stress-strain measurements, and finally the calibration and tests of the device in its complexity.
Wednesday, July 13 at 10:30, new large lecture room
Experimental mechanics and modeling to solve the challenges of manufacturing processes and materials performance
Associate Prof. Víctor Tuninetti, Department of Mechanical Engineering, Universidad de La Frontera, Temuco, Chile
Improving strength, toughness and reducing weight of conventional and new materials are one of the main challenges for today's engineers. We contribute to teaching and new knowledge transfer from experimental mechanics and finite element simulations of part design and manufacturing processes.
Among current developments the talk will include the following topics:
- Design of auxetic materials for ankle implant applications.
- Vibration analysis for industrial processing efficiency in the wood peeling process
- Characterization and modeling of Ti64 plasticity and damage for impact and manufacturing applications.
- Spatially varying filler microstructure in 3D printing fused deposition process based on topology optimization technique.
- Carbon nanotubes for the reinforcement of glass fiber composites.
- Strain rate sensitive behavior prediction of materials using artificial neural networks.
Wednesday, February 9 at 10:30, new large lecture room
From Point-to-Point Connections to Industrial CO2-Transport Networks – Contributions from Thermodynamics
Prof. Dr.-Ing. Roland Span, Chair of Thermodynamics, Faculty of Mechanical Engineering, Ruhr University Bochum, Germany
Concepts for Carbon Capture and Storage or Carbon Capture and Utilization (CCS/CCU) have always considered the transport of CO2 as part of the process chain. However, in many cases transport was considered established technology, or at least little technical problems were seen in the development of transport infrastructure. However, CCS and CCU concepts are no longer restricted to point-to-point connection between large CO2 sources (essentially power plants) and storage sites, but include CO2-transport networks, in which multiple industrial emitters inject CO2. The handling of fluctuating CO2 flows with different origin and separated using different capture technologies results in new challenges for CO2 transport. The talk will present a brief overview of these challenges, focusing on aspects relevant for research in the (wider) field of thermodynamics. With regard to the thermodynamic property basis required for the development of CO2-transport networks, researchers both at Ruhr University and at IT CAS are part of an international network that experimentally and theoretically works on the development of accurate models for both scientific and industrial applications in this context for many years now. An overview of the results of this work will be presented.
- Jäger, V. Vinš, J. Gernert, R. Span, J. Hrubý: Phase equilibria with hydrate formation in H2O + CO2 mixtures modeled with reference equations of state, Fluid Phase Equilib. 338 (2013) 100-113
- Gernert, R. Span: EOS–CG: A Helmholtz energy mixture model for humid gases and CCS mixtures, J. Chem. Thermodynamics 93 (2016) 274-293
- Jäger, V. Vinš, R. Span, J. Hrubý: Model for gas hydrates applied to CCS systems part III. Results and implementation in TREND 2.0, Fluid Phase Equilib. 429 (2016) 55-66
- Jäger, I.H. Bell, C. Breitkopf: A theroretically based departure function for multi-fluid mixture models, Fluid Phase Equilib. 469 (2018) 56-69
- T. Neumann, J. Poplsteinova Jakobsen, M. Thol, R. Span: A new model combining Helmholtz energy equations of state with excess Gibbs energy models to describe reactive mixtures, Chem. Eng. Sci. (2021) in press
Tuesday, January 18, at 13:00, online
Low cycle fatigue behaviour of auxetic cellular structures using the inelastic energy approach
Dr. Branko Nečemer, Faculty of Mechanical Engineering, University of Maribor, Slovenia
Link to the lecture
The talk summarises the research work of low cycle fatigue behaviour of 2D auxetic cellular structures. In the presentation, the development and validation of the computational model based on the inelastic energy approach will be presented. In this study, research was focused on the mechanical characterisation of aluminium alloy 5083-H111, the development and validation of the appropriate computational model and, the numerical and experimental analysis of the given auxetic cellular structures characterised with a negative Poisson’s ratio. The experimental testing of the analysed aluminium alloy included the quasi-static and dynamic testing in the low-cycle fatigue regime. Dynamic tests were performed in a strain control at the strain ratios _ = −1 and _ = 0 at different amplitude strain levels. The experimental results were served as a basis for determining the material constants of the energy approach (c1, c2, c3 and c4) and the material parameters of the constitutive material model, which was then used in the subsequent computational analysis using the Simulia Abaqus software. In the computational model for fatigue life prediction, the algorithm of direct cyclic analysis integrated into the Simulia Abaqus software was used to accelerate the numerical simulation and determination of the fatigue life of the analysed samples. The proposed computational model was first validated based on the comparison of numerical and experimental results of flat and CT samples. Based on the good agreement between the computational and experimental results, the validated computational model was used as a basis for determining the fatigue life of the chiral and re-entrant auxetic structure.
Wednesday, December 15, 2021 at 13:00, new large lecture room
On spatio-temporal analysis of turbulent wake behind a circular cylinder
Prof. Václav Uruba, Institute of Thermomechanics, CAS, v.v.i.
and Faculty of mechanical engineering, University of West Bohemia
The method of spatio-temporal analysis of data is to be presented. The Oscillation Pattern Decomposition (OPD) method is intended for turbulent data analysis containing both random and pseudo-periodical parts. The method is based on approach defined by prof. Hasselmann for meteorological data Principal Oscillation Pattern (POP) employing Fokker-Planck evolution equation. An example of analysis of turbulent wake behind a circular cylinder will be presented. The three modes with corresponding frequencies characterized by Strouhal numbers 0.2, 0.4 and 0.6 respectively representing turbulence harmonic contents are to be shown.
- Hasselmann, K., PIPs and POPs: The Reduction of Complex Dynamical Systems Using Principal Interaction and Oscillation Patterns, J of Geophysical Research, vol. 93, no. D9, pp 11,015-11,021, September 20, 1988.
- Uruba, V., Near wake dynamics around a vibrating airfoil by means of PIV and Oscillation Pattern Decomposition at Reynolds number of 65000, Journal of Fluids and Structures 55 (2015) pp 372–383.
Thursday, November 11, at 13:00, new large lecture room
Technical challenges in the LISA project
and the contribution from the Czech Republic
Prof. Niels Lund, National Space Institute Astrophysics and Atmospheric Physics,
DTU, Copenhagen, Denmark and Institute of Physics of the Czech Academy of Sciences, Prague
The Czech Republic will contribute to ESA’s LISA gravitational wave mission both in the scientific analysis efforts and by delivery of one of the delicate mechanisms on the ultraprecise Optical Benches which are at the heart of the LISA measurement scheme. The Czech instrument contribution is important – but we may hope it will never be used! This may sound strange, but it is like the Fire Brigade; we know it is important – but we hope it will never be user in our neighbourhood!
The LISA project will launch three satellites in a formation flying formation. The technical goal is to measure variations in the inter-satellite distances of 2.5 million km (2.5 109 m) with a precision better than pico-meters (10-12 m), i.e. a relative error of 10-21! Only if we can achieve this level of precision can we detect the small deformation of space caused by the gravitational waves!
In the lecture I shall first briefly describe the very complex measurement scheme of LISA and explain where the Czech contribution comes in.
Wednesday, October 20, at 11:00, new large lecture room
Slow dynamics effects in hysteretic elastic media: physical origin and potentiality for damage detection
Prof. Marco Scalerandi, DISAT, Department of Applied Science and Technology, Politecnico di Torino, Italy
Slow dynamics in hysteretic elastic media consists in the variation over time of the ultrasonic wave velocity when a conditioning strain is applied to the material. The phenomenon consists in three phases: preconditioning, during which velocity is constant (linear velocity); conditioning (i.e. application of a large strain perturbation), during which velocity evolves slowly towards a new equilibrium value; relaxation (when the conditioning strain is set to zero), during which velocity relaxes back slowly to its linear equilibrium value.
This fully reversible effect was shown in materials with a very different microstructure: metal alloys, consolidated granular media (concrete and sandstones), cracked materials and unconsolidated granular media. The presence of contact interfaces between different grains and between crack surfaces seems to be the cause of slow dynamics, but understanding its physical origin (fluids redistribution, dislocations dynamics, sliding and friction …) is still an open issue, mainly because the same physical mechanisms are not taking place in all materials exhibiting elastic hysteresis.
Here, the main experimental observations related to the relaxation process are recalled and the dependence of the effects on some parameters discussed, in view of quantifying the behavior and highlight features, which are universal for all samples, and eventually features, which are not. Finally, some results are presented to discuss how slow dynamics could be used for materials characterization and damage detection. Slow dynamics is indeed a linear measurement (relaxation) of a nonlinear effect, thus it is expected to keep the sensitivity advantages intrinsic in nonlinear ultrasonic NDT while maintaining the simplicity of the experimental set-up typical of linear ultrasonic NDT.
Wednesday, September 29, at 11:00, new large lecture room
Heat conduction in microstructured solids
Dr. Dr. Arkadi Berezovski, Department of Cybernetics, School of Science, Tallinn University of Technology, Estonia / Institute of Thermomechanics, v.v.i., CAS, Prague
The Fourier law is the cornerstone of heat transfer theory and practice. Being well applicable for homogeneous continua, the Fourier law is not sufficient for the description of heat conduction in inhomogeneous solids. Moreover, inner microstructure in a solid can be the source of a hyperbolic character of heat conduction. A variety of phenomenological hyperbolic heat conduction models has been proposed as discussed in [1, 2]. The common feature of the hyperbolic heat conduction models is the extension of the thermodynamic state space by heat flux and/or entropy flux. The most developed approach to the generalization of heat equation is provided by extended irreversible thermodynamics . However, the hyperbolic heat conduction equation is obtained in this framework only under assumption of the independence of internal energy of heat flux. Such an assumption is inconsistent with the main constitutive postulate of the dependence of entropy (and, therefore, internal energy) on temperature and heat flux .
The thermodynamically consistent method of the extension of the state space is provided by the internal variable theory [4, 5]. Internal variables are used for accounting for the influence of inner microstructure on heat conduction. Two variants of the internal variable treatment are compared by means of the numerical simulation of two-dimensional heat conduction in a plate under a localised thermal pulse loading. Computations of the same problem by the different internal variable descriptions produce qualitatively dissimilar results. The single internal variable approach  leads to a diffusional type of the internal variable evolution. In contrast, the dual internal variable technique provides a wave-like evolution of the internal variables, and, as the consequence, the corresponding wave-like heat transfer. The results are obtained in the dimensionless form, and parameters of models are chosen to emphasize the features of each model.
 D. D. Joseph and L. Preziosi, Heat waves, Reviews of Modern Physics, vol. 61, pp. 41–73, 1989.
 B. Straughan, Heat Waves, Springer, New York, 2011.
 D. Jou, J. Casas-Vazquez, G. Lebon, ´ Extended Irreversible Thermodynamics, Springer, New York, 2010.
 B. D. Coleman, M. E. Gurtin, Thermodynamics with internal state variables, The Journal of Chemical Physics, vol. 47, pp. 597–613, 1967.
 G. A. Maugin, W. Muschik, Thermodynamics with internal variables. Part I. General concepts, Journal of Non Equilibrium Thermodynamics, vol. 19, pp. 217–249, 1994.
Wednesday, September 22, at 10:00, new large lecture room
Development of a Solver for Fully Coupled Particle-Laden Flows and Challenges for Model Order Reduction
Dr. Martin Isoz, Institute of Thermomechanics, Czech Acad. Sci.
Particle-laden flows are commonly encountered in numerous aspects of day-to-day life ranging from technical applications such as fluidisation or filtration to medicinal problems, e.g. behavior of clots in blood vessels. However, computational fluid dynamics (CFD) simulations containing freely moving and irregularly shaped bodies are still a challenging topic. More so, if the bodies are densely distributed and large enough to affect the fluid flow. In this work, we present a newly developed finite volume solver for modeling flow-induced movement of arbitrarily-shaped solid particles. The modeling approach is based on a hybrid fictitious domain-immersed boundary method (HFDIB) for inclusion of the solids into the computational domain. The bodies movement and contacts are solved via the discrete element method (DEM). Unfortunately, the coupled HFDIB-DEM model structure causes significant limitations with respect to applications of standard projection-based methods of model order reduction (MOR). In the talk, we give an overview of the new solver implementation an capabilities and comment on the challenges the HFDIB-DEM approach poses for MOR.
Thursday, September 9, 2021 at 13:00, new large lecture room
Surface accretion of a pre-stretched half-plane: Biot’s problem revisited
Prof. Giuseppe Tomassetti, Roma Tre University
Motivated by experiments on dendritic actin networks exhibiting surface growth, we address the problem of its stability. We choose as a simple, reference geometry a biaxially stretched half plane growing at its boundary. Actin is modelled as a neo-Hookean material. A linear kinetic relation is assumed between growth velocity and a stress-dependent driving force for growth. The stability problem is formulated and results discussed for different loading and boundary conditions. Connections are drawn with Biot’s 1963 surface instability threshold.
Thursday, June 24, 2021 at 11:00, online
Fast Fourier Transformation and Finite Element Method
Prof. Miroslav Okrouhlík, Institute of Thermomechanics of the Czech Academy of Sciences, Prague
Link to the lecture
Author intends to show the dispersion phenomenon in general from a historical perspective, also to inform about significant contributions of our forefathers, as Newton, Johan and Daniel Bernoulli’s, Jean Baptiste Joseph Fourier, and first of all to report about the dispersion topic and its role in the computational mechanics. The contemporary Fourier’s tools (as FFT), for the efficient treatment of engineering tasks in Finite Element Method, is reminded as well.
Friday, June 18, 2021 at 11:00, online
Thermomechanics of the Stefan's solid-liquid phase transformation
Prof. Tomáš Roubíček, Institute of Thermomechanics of the Czech Academy of Sciences, Prague
Recorded lecture (passcode: 1*Bnl!V.)
The Stefan problem historically describes melting of ice or freezing (solidification) of water as a mere heat-transfer problem with a latent heat. This solid-liquid phase transition however naturally occurs in a mechanical context: melted liquid can flow while frozen solid exhibits some elasticity or some visco-elasticity and even may undergo some inelastic processes as fracture. This needs also to cope with the fluid-solid (so-called fluid-structure) interaction and calls for a model in Eulerian description. Of course, thermomechanical consistency is an ultimate attribute, too. The concepts of semi-compressible fluids, viscoelastic solids in Jeffreys' rheology, phase-field fracture, and nonsimple materials (known also as multipolar fluids) will be employed. Also superheating/supercooling effects will be involved, as well as a mathematical analysis briefly outlined. Some enhancements of this basic thermomechanical scenario will be mentioned, too.
Wednesday, May 26, 2021 at 10:00, online
Laser Shock Peening (LSP) Laser Explosion and Shear Wave propagation
Prof. František Maršík, Institute of Thermomechanics of the Czech Academy of Sciences, Prague
Link to the lecture record
Although the parameters of the laser pulse are known: the total light energy (5 J), the beam diameter (2.45 mm) and the pulse length (14 ns), the dynamics of the laser explosion itself is unknown. From the point of view of the studied application, the unknown quantities are: the magnitude of the generated pressure in the area of strongly superheated steam (or plasma), the rate of its expansion and its subsequent attenuation. The dynamics of the generated pressure pulse depends on the viscoelastic properties of the irradiated medium (304L austenitic steel) and the absorbing covering medium (water). Physical analysis and numerical simulation show that the magnitude and shape of the residual stress (reinforcement) depends on the choice of material model.
To describe the dynamics of an explosion, the starting point is the balance of the internal energy of the superheated gas (partially ionized water vapor) is needed. The amount of internal energy is given by the absorption of light energy. This energy is then transformed into the required expansion work and is reduced by radiation due to the high temperature.
The consequence of the high pressure magnitude (3-7 GPa) and the high expansion rates (106-109 s-1), shock waves are generated in both water and steel. Due to the existence of these waves, which propagate at a speed greater than the corresponding speed of sound, the pressure reaches extreme values and causes strong defor-mation of the material.
From the point of view of the subsequent strengthening of the material, the dynamics of the shock wave propagation in the steel is decisive. Modeling the consequences of a shock wave is, in addition to the standard elasticity, dependent on the plasticity model of the steel. Both the Ramberg-Osgood hardening model and the Bodner-Parton dislocation movement model are presented in the lecture.
The movement of dislocations can be characterized by the viscosity depending on the rate of deformation. In this way, the material strengthening is explained by overcoming atomic bonds, which coressponds to the hardening work. The movement of dislocations can be modeled by shear waves, which are strongly dispersive. In areas of high viscosity (before the shock wave) they precede the pressure shock wave. The concept of shear waves allows to describe with some accuracy the strengthening of the material due to extremely fast compression.
The presented analysis shows, that to achieve a higher residual stress at the same laser energy, it is more ad-vantageous to use a pulse of shorter length. For greater depth of reinforcement, it is necessary to use a longer pulse. Currently, an experiment is always needed to model LSP. The experimental residual stress data used were provided by the HiLASE Center Institute of Physics CAS. After calibration, the LSP process can also be used to determine the properties of the material under extremely fast loads.
Thursday, April 29, 2021 at 11:00, online
Slow Dynamics as a Multi-Relaxation Phenomenon
Dr. Jan Kober, Department Impact and Waves in Solids, Institute of Thermomechanics of the Czech Academy of Sciences, Prague
Download the lecture
Slow dynamics is a phenomenon associated with elastic hysteresis. When a material is subjected to an external strain excitation, a gradual softening occurs (conditioning phase), once the excitation ends, the material slowly relaxes back to its original state (relaxation phase). This behavior was generally associated with consolidated granular materials such as rocks or concrete, but it was also found in damaged metals, where it manifests in a much more limited extent. The physical origins of slow dynamics are generally attributed to intergrain/interfacial mechanics and friction. As such, it is reasonable to expect, that the relaxation process incorporates some information about the material structure. It was shown, that the relaxation process can be interpreted as a superposition of exponential decays with varying time scales. This multi-relaxation model can be used as a stepping stone to a perhaps more physical model of continuous distribution of decay times. By analyzing relaxation curves of various materials, a link between the distribution peak location and grain size was found. Moreover, when a material damage is on a larger size scale than the microstructure, as is a case for e.g., cracks, bimodal relaxation times distributions were observed. The research of slow dynamics is challenging in various aspects ranging from the experimental management requiring fast and extremely precise velocity measurements, to data post-processing, where a careful parameter optimization is necessary.
By attending this online event you consent that we may take a screenshot of the participants and provide it to the Ministry of Education, Youth and Sports (MEYS). MEYS is the funding provider for project CZ.02.2.69/0.0/0.0/18_053/0017555, "Support of international mobility of researchers of the Institute of Thermomechanics of the CAS" and the processor of the provided data.
Monday, March 8, 2021 at 13:30, online
Laser shock peening, principal, use and related phenomena
Dr. Jan Brajer, HiLASE Centre, Institute of Physics, Czech Acad. Sci., Dolní Břežany
Online meeting links
The laser shock peening (LSP) process using a Q-switched pulsed laser beam for surface modification. The development of the LSP technique and its numerous advantages over the conventional shot peening (SP) such as better surface finish, higher depths of residual stress and uniform distribution of intensity. The generation of shock waves, processing parameters, and characterization of LSP treated specimen is great topic for deeper understanding. Special attention will be given to the influence of LSP process parameters on residual stress profiles, material properties and structures. Based on the studies so far, more fundamental understanding is still needed when selecting optimized LSP processing parameters and substrate conditions. Furthermore, enhancements in the surface micro and nanohardness, elastic modulus, tensile yield strength and refinement of microstructure which translates to increased fatigue life, fretting fatigue life, stress corrosion cracking (SCC) and corrosion resistance will be discused with audience.
Wednesday, January 27, 2021 at 13:30, online
Numerical simulations of flexible multibody systems described by absolute nodal coordinate formulation
Ing. Radek Bulín, Ph.D., Department of Mechanics, Faculty of Applied Sciences, University of West Bohemia
Online meeting links
A large group of real mechanical problems can be modelled and analysed using the approaches of flexible multibody dynamics. The computational models in the form of differential-algebraic equations can be quite complex and therefore it is suitable to develop both efficient and accurate approaches for the dynamic analysis of such model. This talk will be dedicated to the description of various finite elements defined by the absolute nodal coordinate formulation (ANCF), which is suitable for modelling of flexible bodies that undergo large displacements, rotations and deformations. Eligible numerical technics for effective evaluation of the elastic forces as well as suitable integration schemes for multibody systems containing the ANCF elements will be discussed.
Wednesday, January 27, 2021 at 13:00, online
Dynamics of large rotating systems – methods and applications
doc. Ing. Michal Hajžman, Ph.D., Department of Mechanics, Faculty of Applied Sciences, University of West Bohemia
Online meeting links
Thursday, December 10, 2020 at 13:00, online
Experimentally Validated Enhanced Constitutive Model of NiTi-based Shape Memory Polycrystals
RNDr. Miroslav Frost, Ph.D., Institute of Thermomechanics, Czech Acad. Sci.
Online meeting links
Monday, November 2, 2020 at 13:00, online
Design and analysis of membrane structures
Dr. Rostislav Lang, Faculty of Civil Engineering, Brno University of Technology and FEM consulting, s.r.o.
Online meeting links
Wednesday, September 16, 2020, 10:00 CET, lecture room B
Corrosion study in subcritical and supercritical water: An electrochemical approach
Prof. Jan Macák, Department of Power Engineering, Faculty of enviromental technology, University of Chemistry and Technology Prague
Tuesday, May 13, 2020, 1pm CET, online lecture
High-order methods in simulations of fluid dynamics problems
Dr. Jan Pech, Institute of Thermomechanics, Czech Academy of Sciences
Online meeting links
Tuesday, May 6, 2020, 1pm CET, online lecture
Advanced Titanium Alloys for Medical Applications
Dr. Josef Stráský, Faculty of Mathematics and Physics, Charles University
Online meeting links
Tuesday, April 29, 2020, 1pm CET, online lecture
Achievements, agreements and quarrels of forefathers of mechanics
Prof. Miloslav Okrouhlík, Institute of Thermomechanics of the CAS
Online meeting links
Tuesday, April 21, 2020, 1pm CET, online lecture
Application of boundary element type methods in computational aerodynamics
Dr. Chandra Shekhar Prasad, Institute of Thermomechanics of the CAS
Wednesday, April 15, 2020 at 13:00, online
Models of „semi-compressible“ fluids as a compromise between incompressible fluids and compressible gasses
Prof. Tomáš Roubíček, Institute of Thermomechanics of the CAS
Wednesday, March 11, 2020 at 10:00, Lecture Room B
Thermomechanics in optical fibre drawing, splicing, and everyday use
Prof. Pavel Honzátko, Institute of Photonics and Electronics of the Czech Academy of Sciences
Thursday, February 27, 2020 at 14:00, Lecture Room B
Structural Design and Analysis at OHB System AG
Dr. Markus Geiß, Structural and Thermal Development Engineer, OHB System AG, Weßling, Germany
Monday, February 17, 2020 at 10:00, Lecture Room B
Experimental and Numerical Procedures for Calibration of Advanced Phenomenological Models of Metal Plasticity
Dr. Slavomír Parma, Institute of Thermomechanics, Czech Academy of Sciences
Wednesday, January 8, 2020, 10:00, Lecture Room B
First-principles calculations of elastic constants for complex systems
Ing. Martin Zelený, Ph.D., Brno University of Technology
Monday, December 9, 2019, 13:00, Lecture Room B
Application of the method of localized Lagrange multipliers to the partitioned solution of large-scale structural dynamic systems: The AFETI algorithm
Prof. José González, Universidad de Sevilla, Spain
Friday, December 6, 2019, 11:00, Lecture Room Klub
Cavitation and separation during water entry and exit
Alexander Korobkin, Professor in Applied Mathematics
Wednesday, December 4, 2019, 10:00, Lecture Room B
Properties of open thermodynamic systems as the consequence of their stability
Prof. František Maršík, DrSc., Institute of Thermomechanics, The Czech Academy of Sciences, University of West Bohemia, Faculty of Physical Education and Sport, Charles University
Friday, November 15, 2019, 10:00, Lecture Room B
Model reduction for the FEM of solids applied to the Rayleigh-Ritz computation of the free vibration spectrum
Prof. Petr Krysl, University of California, San Diego
Wednesday, November 13, 2019, 13:00, Lecture Room B
Non-coaxiality between two tensors: Application to stress rate decomposition and non-coaxial invariants
Prof. Yannis F. Dafalias, Institute of Thermomechanics of the Czech Academy of Sciences, Prague
Tuesday, November 5, 2019, 10:00, Lecture Room A
Notes on Experimental Research on Transonic Compressor Blade Cascades
Dr. David Šimurda, Institute of Thermomechanics of the Czech Academy of Sciences, Prague
Tuesday, October 22, 2019, 12:00, Lecture Room A
The Energy-Sampling Stabilization of Nodally Integrated Continuum Elements for Dynamic Analyses
Prof. Petr Krysl, University of California, San Diego
Monday, October 21, 2019, 10:00, Lecture Room B
Lessons to be learned from German Attempts to Reduce Atmospheric CO2-Emissions
Prof. Dr-Ing. Roland Span, Ruhr University Bochum, Germany
Wednesday, October 2, 2019, 10:00, Lecture Room B
Digital image correlation: from static tests to X-ray tomography and high strain-rate loading
Prof. Ondřej Jiroušek, Faculty of Transportation Sciences, Czech Technical University in Prague
Wednesday, October 2, 2019, 10:30, Lecture Room B
High Strain-rate Experiments Using Hopkinson Bar: Application on Cellular Metals and Additively Manufactured Auxetic Structures
Ing. Tomáš Fíla, Faculty of Transportation Sciences, Czech Technical University in Prague
Monday, September 23, 2019, 14:00, Lecture Room A
Twin mortar method: A new unbiased mesh tying formulation
Ing. Ján Kopačka, Ph.D., Institute of Thermomechanics, Czech Academy of Sciences
Monday, September 23, 2019, 13:00, Lecture Room A
Recent Advances in Wave Propagation and Large-Step Transient Analysis Procedures
Prof. K. C. Park, Ann & H.J. Smead Aerospace Engineering Sciences, University of Colorado, Boulder, Colorado, USA
Wednesday, September 18, 2019, 10:00, Lecture Room B
Film-based shear stress sensor
Ing. Zuzana Broučková, Ph.D., Institute of Thermomechanics, Czech Academy of Sciences
Wednesday, August 9, 2019, 10:00, Lecture Room B
The Martensitic Transformation in In-Tl Alloys Revisited
Prof. Trevor R. Finlayson, University of Melbourne, Australia
Wednesday, July 31, 2019, 10:00, Lecture Room B
Control of Grid-side Converters under Grid Imbalance
Prof. Yongsug Suh, Ph.D., Chonbuk National University, Jeonju, Korea
Wednesday, June 12, 2019, 10:00, Lecture Room B
Stress waves and people in the Institute of Thermomechanics
Prof. Miloslav Okrouhlík, Institute of Thermomechanics of the Czech Academy of Sciences, Prague
Monday, June 10, 2019, 13:00, Lecture Room B
Shock wave propagation in complex media: an experimental contribution to dynamic behavior of materials at very high strain rates
Prof. Michel Arrigoni, ENSTA Bretagne, Brest, France
Wednesday, April 3 2019, 10:00, Lecture Room B
A parallel multilevel domain decomposition solver and its application to adaptive finite element method
Dr. Jakub Šístek, Institute of Mathematics of the CAS
Thursday, March 21, 2019, 10:00, Lecture Room B
Decomposition of waves, stresses and forces in rotating disks
Prof. Izhak Bucher, Mechanical Engineering, Technion, Haifa, Israel
Thursday, March 21, 2019, 11:00, Lecture Room B
Thermodynamical modeling via GENERIC: from quantum mechanics to semiconductor devices
Prof. Alexander Mielke, Weierstrass Institute for Applied Analysis and Stochastics, and Humboldt University Berlin
Wednesday, March 6, 2019, 10:00, Lecture Room B
Rekonstrukce minulých klimatických změn z měření teploty v hlubokých vrtech
Jan Šafanda, Institute of Geophysics of the CAS
Wednesday, February 13, 2019, 10:00, Lecture Room B
Theoretical and implementation problems of the multi-dimensional Fokker-Planck equation analysis using the Finite Element Method
Dr. Jiří Náprstek, Institute of Theoretical and Applied Mechanics of the CAS
Wednesday, January 9, 2019, 10:00, lecture room B
Dynamical damage and phase-field fracture models
Tomáš Roubíček, Institute of Thermomechanics of the CAS
Tudesday, December 18, 2018, 11:00, Lecture Room B
Active grids as a tool for turbulence and wind energy studies
Jason Hearst, Department of Energy and Process Engineering, Faculty of Engineering, Norwegian University of Science and Technology, Trondheim, Norway
Wednesday, December 5, 2018, 10:00, Lecture Room B
Use of FEM to provide virtual functionality for car body development in ŠKODA AUTO a. s.
Ing. Jan Korouš, Ph.D., ŠKODA AUTO a.s.
Tuesday, November 6, 2018, 14:00, Lecture Room B
Wednesday, November 7, 2018, 14:00, Lecture Room B
Friday, November 9, 2018, 14:00, Lecture Room B
Lecture series on Computational Plasticity
Prof. Nikolaos Aravas, University of Thessaly, Greece
Wednesday, November 7, 2018, 10:00, Lecture Room B
Europe without USA – not just in the energy sector
Václav Bartuška, Special envoy of the Czech Republic for Energy Security, Ministry of Foreign Affairs of the Czech Republic
Wednesday, November 7, 2018, 10:30, Lecture Room B
New role of silicon thin films in advanced photovoltaics
Antonín Fejfar, Institute of Physics of the Czech Academy of Sciences, Prague
Wednesday, October 3, 2018, 10:00, Lecture Room B
The development of Fuel Cell & Energy Storage technologies in ITRI – Status and Prospective
Wen-Sheng Chang, Director, Division of Energy Storage Technology, Green Energy and Environment Research Laboratories, ITRI
Wednesday, October 3, 2018, 10:40, Lecture Room B
Nanoparticle synthesis by spark discharge
Tomáš Němec, Institute of Thermomechanics of the Czech Academy of Sciences, Prague
Thursday, November 7, 2018, 10:00, Lecture Room B
New role of silicon thin films in advanced photovoltaics
Antonín Fejfar, Institute of Physics of the Czech Academy of Sciences, Prague
Thursday, September 6, 2018, 10:00, Lecture Room B
Predicting low and high friction in rotating mechanisms
Juan Carlos Jauregui, Universidad Autonoma de Queretaro, Mexico
Friday, June 22, 2018, 12:00, Lecture Room B
A nonlinear continuum theory of finite deformations of elastoplastic media
Doc. Ing. Ladislav Écsi, PhD., Faculty of Mechanical Engineering, Slovak University of Technology in Bratislava
Wednesday, June 6, 2018, 11:00, Lecture Room B
IMPLEMENTATION AND APPLICATIONS OF A GENERAL MODEL FOR VARIOUS CONTACTS WITH ADHESION AND/OR FRICTION
Doc. Ing. ROMAN VODIČKA, PhD., Faculty of Civil Engineering, Technical University of Kosice
Friday, June 1, 2018, 10:00, Lecture Room B
Developments in Fluid-Structure Interaction Modeling and Analysis
Prof. K. C. Park, Center for Aerospace Structures and Department of Aerospace Engineering Sciences University of Colorado, Boulder
Tuesday, April 10, 2018 at 13:00, Lecture Room B
Behaviour of brittle materials under dynamic loading
Jaroslav Buchar and Jan Trnka, Institute of Thermomechanics, Czech Academy of Sciences
Wednesday, March 28, 2018 at 11:00, Lecture Room B
Finite Fracture Mechanics and its Applications to Composite Materials
Vladislav Mantič, Department of Continuum Mechanics and Structural Analysis, School of Engineering, University of Seville, Spain
Wednesday, March 28, 2018 at 14:00, Lecture Room B
Brief introduction to optimization and topology optimization
Dr. Paulo Salvador Britto Nigro, Software Developer and Researcher of Virtual.PYXIS optimization, São Paulo, Brazil
Wednesday, March 28, 2018 at 10:00, Lecture Room B
Micromechanics of Martensitic Laminates
Doc. Ing. Hanuš SEINER, Ph.D., Institute of Thermomechanics, Czech Academy of Sciences / Visiting Fulbright Scholar at the University of Minnesota, Minneapolis, USA
Wednesday, March 7, 2018 at 10:00, Lecture Room B
Catch the yield surface, experimentally, theoretically, and computationally
Dr. Li-Wei Liu, Department of Civil Engineering, National Taiwan University, Taipei 10617, Taiwan / Institute of Thermomechanics of CAS, v. v. i., Prague
Thursday, February 15, 2018 at 14:00, Lecture Room B
Complementary near field technique for assessment of materials with added value
Dr. Adriana Savin, Head of Nondestructive Testing Department, National Institute of Research and Development for Technical Physics, Iasi, Romania
January 25, 2018, 14:00 Lecture Room B
Evolution and Verification of a Kinematic Hypothesis for Splitting of the Strain Energy
Prof. Herbert A. Mang, Institute for Mechanics of Materials and Structures, Vienna University of Technology
6. 12. 2017, 10:00
Research on synthetic jets
Assoc. Prof. Zdeněk Trávníček, Institute of Thermomechanics, v.v.i., CAS, Prague
15. 11. 2017, 10:00
Modelling of yield surface distortion in the finite strain range
Prof. A.V. Shutov, Lavrentyev Institute of Hydrodynamics, Novosibirsk State University
10. 11. 2017, 10:00
Cellular structures and materials – fabrication, properties characterisation and applications
Zoran Ren, Srečko Glodež, Matej Vesenjak and Nejc Novak, University of Maribor, Faculty of Mechanical Engineering, Maribor, Slovenia
1. 11. 2017, 11:00
On gravitational waves and 2017 Nobel Prize for Physics
Prof. Jiří Chýla, Institute of Physics of the Czech Academy of Sciences
2. 10. 2017, 11:00
Internal Variables associated with Microstructure
Dr. Arkadi Berezovski, Department of Cybernetics, School of Science, Tallinn University of Technology
2. 10. 2017, 10:00
2D Discrete Spectral Analysis – A Tool for Examining of omplicated Wave Structures
Prof. Andrus Salupere, Department of Cybernetics, School of Science, Tallinn University of Technology (in collaboration with Mart Ratas)
17. 8. 2017, 11:00
Recent advances in reciprocal mass matrices
Dr. Anton Tkachuk, Institute for Structural Mechanics, University of Stuttgart, Stuttgart, Germany (in collaboration with Anne Schäuble, Prof. Manfred Bischoff)
17. 8. 2017, 10:00
Multi-Scale Structural Gradients Optimize the Bio-Mechanical Functionality of the Spider Fang
Dr. Benny Bar-On, Laboratory for the Mechanics of Complex Materials, Department of Mechanical Engineering, Ben-Gurion University of the Negev
26. 6. 2017, 10:00
Modelling extreme deformation and dynamic behaviour of materials using mesh-less methods
Dr. Raj Das, Sir Lawrence Wackett Aerospace Research Centre, School of Engineering, RMIT University, Australia
19. 6. 2017, 10:00
Additive Manufacturing of metals: Past, today and tomorrow
Dr. Edson Costa Santos, SENAI Innovation institute in Laser Processing, Joinville, Santa Catarina, Brazil
15. 6. 2017, 10:00
Quasibrittle Failure Probability and Scaling
Prof. Zdeněk P. Bažant, Northwestern University, Evanston, Illinois, USA
30. 5. 2017, 15:00
ISG-Israel Smart Grid consortium and Large-Scale Power System Dynamics
Prof. Yuval Beck, Head of Power Engineering, Faculty of Engineering, Holon Institute of Technology, Israel
Prof. Yoash Levron, Professor of Electrical Engineering, Faculty of Electrical Engineering, Technion – Israel Institute of Technology
3. 5. 2017, 10:00
Non-standard damped oscillators
Prof. Dalibor Pražák, Department of Mathematical Analysis, Faculty of Mathematics and Physics, Charles University in Prague
5. 4. 2017, 10:00
Implosive magnetocumulative generator for effective energy conversion
Dr. Jiří Šonský, Institute of Thermomechanics of the CAS, v. v. i.
1. 3. 2017, 10:00
Atmospheric Boundary Layer: main characteristics and methods of the research in context of continuum mechanics
Prof. Zbyněk Jaňour, Institute of Thermomechanics of the CAS, v. v. i.
14. 2. 2017, 10:00
Modelling of complex processes in nanopowder fabrication using thermal plasma flows
prof. Masaya SHIGETA, Joining and Welding Research Institute, Osaka University, Japan
1. 2. 2017, 10:00
Highlights of plasma spraying in the life of one researcher
Dr. Tomáš Chráska, Institute of Plasma Physics of the CAS, v. v. i.
4.1. 2017, 10:00
Usage of time reversal signal processing in nondestructive diagnostics of materials and structures
Dr. Zdeněk Převorovský, Institute of Thermomechanics of the CAS, v. v. i.
28 December 2016, 11:00
Modelling of lotus-type porous structures: bi- and multi- axial loading
Assoc. prof. dr. Matjaž Šraml, University of Maribor, Slovenia
7 December 2016, 10:00
Iron. Static and „dynamic“ phase diagrams and transformation kinetics
Prof. Eugene B. Zaretsky, Department of Mechanical Engineering, Ben Gurion University, Beer Sheva, Israel
November 9, 2016, 10:00
Regularized Models for Softening Materials
Prof. Milan Jirásek, Czech Technical University in Prague, Faculty of Civil Engineering
5 October 2016, 10:00
Experimental study and simulation on localization of phase transformation in shape memory alloys
Ing. Petr Sedlák, Ph.D., Institute of Thermomechanics of the CAS, v. v. i.
15 September 2016, 10:00
Effects of the nozzle exit boundary layer on hot-jet mixing
Ing. Jan Lepičovský, DrSc., Institute of Thermomechanics of the CAS, v. v. i.
17 August 2016, 10:00
Rotation-free parametrization and isogeometric analysis of shear deformable plates and shells
Prof. Dr.-Ing. habil. Manfred Bischoff, Institut für Baustatik und Baudynamik, Universität Stuttgart
2 June 2016, 10:00
Mathematics of fluids in motion
Prof. Eduard Feireisl, Institute of Mathematics of the CAS, v. v. i.
4 May 2016, 10:00
Development of Human Artificial Vocal Folds
Dr. Jaromír Horáček, Institute of Thermomechanics of the CAS, v. v. i.
6 April 2016, 10:00
Stochastic Self-Organization in Inner Structure of Vehicular Systems
Prof. Milan Krbálek, Faculty of Nuclear Sciences and Physical Engineering, Department of Mathematics, Czech Technical University in Prague
2 March 2016, 13:30
Dr. Rudolf Dvořák, Institute of Thermomechanics of the CAS, v. v. i.
3 February 2016, 10:00
FLUIDIC OSCILLATORS FOR ALGAE CULTIVATION and their role in geopolitic stability
Prof. Ing. Václav Tesař, CSc., Institute of Thermomechanics of the CAS, v. v. i.
6 January 2016, 10:00
Discontinuous Galerkin method for the solution of elasto-dynamic, compressible flow and fluid-structure interaction problems
Prof. Miloslav Feistauer, Department of Numerical Mathematics, Faculty of Mathematics and Physics, Charles University in Prague
2 December 2015, 10:00
Fractography and Failure Analysis
Prof. Jan Siegl, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague
4 November 2015, 10:00
Scalable algorithms for the solution of contact problems with 10e9 unknowns
Prof. Zdeněk Dostál, Faculty of Electrical Engineering and Computer Science, VŠB – Technical University of Ostrava
12 October 2015, 13:30
Aerodynamic Control using Virtual Surface Modification
Prof. Ari Glezer, Woodruff School of Mechanical Engineering, Georgia Institute of Technology
7 October 2015, 10:00
Multi-Phase Electric Machines and Drives
Prof. Miroslav Chomát, Institute of Thermomechanics of the CAS, v. v. i.
3 June 2015, 10:00
Ultrasonic characterization of advanced material
Dr. Michal Landa, Institute of Thermomechanics of the CAS, v. v. i.
6 May 2015, 10:00
Application of contact algorithm in creep analysis of high-pressure casing DSPWR
Dr. Dušan Gabriel, Institute of Thermomechanics of the CAS, v. v. i.
1 April 2015, 10:00
Experimental and theoretical research of friction coupling effect on dynamics of bladed discs
Dr. Luděk Pešek, Institute of Thermomechanics of the CAS, v. v. i.
4 March 2015, 10:00
The Department of Thermodynamics at a glance and research of the homogeneous nucleation of droplets
Dr. Jan Hrubý, Institute of Thermomechanics of the CAS, v. v. i.
4 February 2015, 10:00
Aerodynamic Research on the Tip Sections of Long Rotor Turbine Blades
Dr. Martin Luxa, Institute of Thermomechanics of the CAS, v. v. i.
Wednesday, December 3, 2014, 10:00
Mikrokosmos a makrokosmos: Záhady a souvislosti
Prof. Jiří Chýla, Fyzikální ústav AV ČR, v. v. i., Praha