National Repository of Grey Literature 58 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Spectral collocation methods in solid mechanics
Trnka, Ladislav ; Průša, Vít (advisor) ; Zeman, Jan (referee)
Spectral collocation methods are advertised as a powerful tool for a numerical so- lution of boundary value problems for ordinary as well as partial differential equations. The methods are based on a polynomial approximation, typically using Chebyshev poly- nomials. In one-dimensional setting, the properties of the methods are well known, and there exist several software packages implementing the methods. Our goal is to assess the applicability of spectral collocation methods in solving two-dimensional boundary value problems. We solve a classical problem in linearised two-dimensional elasticity, namely the deflection of a semi-infinite elastic medium subject to a surface load. The numerical results are compared to the analytical solution, which allows us to evaluate the performance of the given numerical method in solving boundary value problems in linearised elasticity. 1
Matematické modelování magnetosriktních látek
Vermach, Lukáš ; Kružík, Martin (advisor) ; Zeman, Jan (referee)
4 Title: Mathematical modeling of magnetostrictive materials Author: Lukáš Vermach Department: Mathematical Institute of Charles University Advisor: Priv.-Doz. Dr. habil. RNDr. Martin Kružík Ph.D., Institute of Information Theory and Automation, Academy of Sciences of the Czech Republic Advisor's e-mail address: kruzik@utia.cas.cz Abstract In the present work we introduce an isotermic mathematical model of ferromagnetic shape memory alloys (FSMAs). FSMAs are a special class of magnetostrictive materials, i.e. materials which deform their shape on account of external magnetic field or which change magnetization as a consequence of strain. This property originates from phase transformations that occur within the material when being exposed to external loading. First, the stationary model of FSMA is formulated. The thermodynamical potential is composed (Helmholz free energy) and its non-quasiconvexity is discussed. The quasicon- vexification is performed via the relaxation theory, i.e. quasiconvex envelope construction. For such a model the existence theory is built. Then, taking advantage of the stationary case the evolutionary model is developed. The attention is drawn to hysteresis, which arises from energy dissipation. The time discretization leads to a sequence of hysteresis-modified stationary problems (the...
Goal-oriented a posteriori error estimates and adaptivity for the numerical solution of partial differential equations
Roskovec, Filip ; Dolejší, Vít (advisor) ; Kanschat, Guido (referee) ; Zeman, Jan (referee)
A posteriori error estimation is an inseparable component of any reliable numerical method for solving partial differential equations. The aim of the goal-oriented a posteriori error estimates is to control the computational error directly with respect to some quantity of interest, which makes the method very convenient for many engineering applications. The resulting error estimates may be employed for mesh adaptation which enables to find a numerical approximation of the quantity of interest under some given tolerance in a very efficient manner. In this thesis, the goal-oriented error estimates are derived for discontinuous Galerkin discretizations of the linear scalar model problems, as well as of the Euler equations describing inviscid compressible flows. It focuses on several aspects of the goal-oriented error estimation method, in particular, higher order reconstructions, adjoint consistency of the discretizations, control of the algebraic errors arising from iterative solutions of both algebraic systems, and linking the estimates with the hp-anisotropic mesh adaptation. The computational performance is demonstrated by numerical experiments.
Variational Methods in Thermomechanics of Solids
Pelech, Petr ; Kružík, Martin (advisor) ; Dondl, Patrick (referee) ; Zeman, Jan (referee)
The thesis is devoted to study of continuum mechanics and thermodynamics and the related mathematical analysis. It consists of four self-contained chapters dealing with different aspects. The first chapter focuses on peridynamics, a non-local theory of continuum mechanics, and its relation to conventional local theory of Cauchy-Green elasticity. Similar compar- isons has been used for proving consistency and for determining some of the material coefficients in peridynamics, provided the material parameters in the local theory are known. In this chapter the formula for the non-local force-flux is computed in terms of the peridynamic interaction, relating the fundamental concepts of these two theories and establishing hence a new connection, not present in the previous works. The second and third chapters are both devoted to Rate-Independent Systems (RIS) and their applications to continuum mechanics. RIS represents a suitable approximation when the internal, viscous, and thermal effects can be neglected. RIS has been proven to be useful in modeling hysteresis, phase transitions in solids, elastoplasticity, damage, or fracture in both small and large strain regimes. In the second chapter the existence of solutions to an evolutionary rate-independ- ent model of Shape Memory Alloys (SMAs) is proven. The model...
Relaxace v mechanice kontinua tuhé fáze
Pathó, Gabriel ; Kružík, Martin (advisor) ; Zeman, Jan (referee)
This work deals with the modelling of shape-memory alloys, in particular with the steady-state model of martensitic thin films. After the introductory motivation the crystallographic structure of the materials is described followed by the introduction of the link between the lattice and continuum model. The next parts of the work focus on the possible solutions of the given 3D variational problem (quasiconvexification, Young measures) and on derivation of thin film theories with the aid of different tools (regularization,-convergence). The last part takes over an approximation of an obtained model and sketches numerical experiments on a Ni-Mn-Ga alloy.
Biological effects of shock waves generated by multichannel discharge
Zeman, Jan ; Beneš, Jiří (advisor) ; Šunka, Pavel (referee)
Shock waves are generally characterized by a sharp change of the pressure, which causes subsequent changes in properties of the surrounding in which it spreads. In medical applications, it is an acoustic shock wave which is used for the treatment of concrements for more than 25 years. This success naturally led to considerations about the possibility of using shock waves in other areas of medicine. One of the main directions of the research is the possibility of the damage to tumor tissue. In contrast to concrements the tumor tissue is not different from surrounding tissues by its acoustic attributes, so the normal lithotryptor is not appropriate for this application. Therefore, there has been developed a new source of shock waves, which is based on the principle of multichannel discharge on the composite anode. The experiments demonstrated the effect of the new source on the acoustically homogeneous tissue of the thigh muscle at a depth of rabbit in vivo. Then there was observed the damage to tumor tissue in vivo in rats. Finally, there was observed the damage to tumor tissue in vivo in rats in the combination with cisplatin and Photosan. It was found that the new source of shock waves can cause the damage to the acoustically homogeneous tissue in vivo in depth. It also can damage the tumor...
Creating the learning programme for facilitating the higher education school choice and verifying its benefits
Zeman, Jan ; Valenta, Josef (advisor) ; Valášková Vincejová, Eva (referee)
The thesis aims at improving the process of choosing a university by designing an experimental educational course composed of activities focused on self-knowledge and working with information. The theoretical part includes an overview of the existing research about higher education school choice. To create suitable activities, it was necessary to know the importance of choice factors, prospective students' needs and the facts about current sources of information. The thesis also presents the current state of career consulting and courses focused on a similar subject. The empirical part describes the content of the online educational workshop and its implementation including students' evaluation. The verification of the course's benefits was secured by interviews with the students and by evaluation of their learning outcomes from the activities. Furthermore, the thesis contains a description of the research limits caused by the Covid-19 pandemic and a recommendation for future improvements and methodical use. Key words: Higher education choice, career consulting, prospective student, decision-making, designing methodology
Use of regenerative procedures by students of UK FTVS
Zeman, Jan ; Majorová, Simona (advisor) ; Nováková, Pavlína (referee)
Title of the bachelor thesis: Use of regenerative procedures by students of UK FTVS Department: Department of Health Physical Education and Sport Medicine Supervisor: MUDr. Simona Majorová Goals: The main aim of the thesis was to find out which regeneration procedures UK FTVS students use the most, identify the main reason for use and the factors determining the selection of the regenerations procedure. The secondary objective was to summarize and characterize regeneration forms and resources on the basis of porfessional literature dealing with regeneration in sport. Than on the basis of the survey results with regards of professional literature make regeneration recommendation for students in practice. Metohods: The necessary informations was collected by using a non - invasive method of online survey. A total of 60 UK FTVS students from domain TVS participated in the research, across all grades regardless of gender. Results: On the basis of online survey was found that the most used thermal regeneration procedure among students is sauna, water procedure is swimming pool - swimming, the most used type of massage is sports massage and light procedures are not used by the vast majority of students. For electroprocedures, we chose only a questions about the experience with them, because of the need...
Possibilities of clinical use single and tandem shock waves.
Zeman, Jan ; Beneš, Jiří (advisor) ; Kneppo, Peter (referee) ; Bolek, Lukáš (referee)
Shock waves have been used in medicine for more than 30 year. At the beginning was mainly use for lithotripsy, but today is also applied in other fields of medicine, such as orthopedics, rheumatology and others. Single shock wave is one shock that usually is repeated every 1-1.5 seconds. By contrast tandem shock waves are two shocks consecutively (ideal interval between shocks is from 8 to 15 microseconds), that are repeated. In this work we investigated the clinical use of single and tandem shock waves that are generated entirely new source. It is based on the principle of multichannel discharge. It was found that a single shock wave can destroy the union between bone and bone cement, this effect could be used in orthopedics. Single and tandem shock wave can damage the tumor in vivo, but the principle damage is different. Tandem shockwave is able to cause damage in a depth of acoustically homogeneous medium and enhances the effect of chemotherapy. It would therefore be possible to used single and tandem shock waves in oncology either alone, or their combination with other chemicals. Functional sample of clinically usable applicator of shock waves with a new source was made for these applications. Powered by TCPDF (www.tcpdf.org)

National Repository of Grey Literature : 58 records found   1 - 10nextend  jump to record:
See also: similar author names
36 ZEMAN, Jan
16 ZEMAN, Jaroslav
2 Zeman, J.
16 Zeman, Jakub
16 Zeman, Jaroslav
18 Zeman, Jiří
3 Zeman, Josef
2 Zeman, Juraj
Interested in being notified about new results for this query?
Subscribe to the RSS feed.