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Engineering Mechanics 2000
Náprstek, Jiří ; Minster, Jiří
The Conference has been focused on general area of Engineering Mechanics: Analysis, modelling and simulation in Mechanics of Solids,, Fluids and Thermodynamics, Problems of non-linear and stochastic dynamics, Diagnostic and identification methods in Mechanics, Interdisciplinary problems in Mechanics,Fracture Mechanics, Complex problems in mechanical systems, Reliability of mechanical systems.
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Dimensional transmutation in quantum theory
Ebr, Jan ; Hořejší, Jiří (advisor) ; Novotný, Jiří (referee)
This work deals with two models - from the quantum eld theory it is the massless scalar electrodynamics (the so-called Coleman-Weinberg model) and from quantum mechanics it is the contact (-function) potential (in two dimensions) - that are apparently invariant under some sort of scale transformations and thus they, in suitably chosen units, contain only dimensionless parameters. It turns out that even in the quantum-mechanical case one has to add an additional procedure to the formal denition of the model and that the use of dierent physical regulators leads to the same results, that furthermore agree with the predictions of the mathematically rigorous method of self-adjoint operator extensions. In this work, we present detailed calculations supporting this result. Contrary to the common literature, we do so in a straightforward manner, which can be followed step by step (with all the necessary elements of functional analysis summarised in the Appendix). In quantum eld theory we apply a similar approach, when we "rediscover" the results of the abstract functional methods in the ordinary perturbation theory. In its framework, we further show how to obtain predictions also for other quantities than particle masses.
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STRAIN ENGINEERING OF THE ELECTRONIC STRUCTURE OF 2D MATERIALS
del Corro, Elena ; Peňa-Alvarez, M. ; Morales-García, A. ; Bouša, Milan ; Řáhová, Jaroslava ; Kavan, Ladislav ; Kalbáč, Martin ; Frank, Otakar
The research on graphene has attracted much attention since its first successful preparation in 2004. It possesses many unique properties, such as an extreme stiffness and strength, high electron mobility, ballistic transport even at room temperature, superior thermal conductivity and many others. The affection for graphene was followed swiftly by a keen interest in other two dimensional materials like transition metal dichalcogenides. As has been predicted and in part proven experimentally, the electronic properties of these materials can be modified by various means. The most common ones include covalent or non-covalent chemistry, electrochemical, gate or atomic doping, or quantum confinement. None of these methods has proven universal enough in terms of the devices' characteristics or scalability. However, another approach is known mechanical strain/stress, but experiments in that direction are scarce, in spite of their high promises.\nThe primary challenge consists in the understanding of the mechanical properties of 2D materials and in the ability to quantify the lattice deformation. Several techniques can be then used to apply strain to the specimens and thus to induce changes in their electronic structure. We will review their basic concepts and some of the examples so far documented experimentally and/or theoretically.
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Laser cooling of the trapped ions for frequency and time metrology
Číp, Ondřej ; Pham, Minh Tuan ; Čížek, Martin ; Lešundák, Adam ; Hucl, Václav ; Hrabina, Jan ; Řeřucha, Šimon ; Jedlička, Petr ; Lazar, Josef
In the laser cooled trapped ions field current research is oriented to yield isolated ions in their basic state of the motion. The detection of the Doppler cooled iont excitation to its quadrupole transition of the electronic structure gives the opportuniny to stabilize highly coherent lasers of the optical frequency of the hundreds of THz. This way a new standart of the time or optical frequencies called „Optical atomic clock“ can be defined. Institute of the Scientific Instruments in Brno in the cooperation with the Department of the Optics of the Palacky University in Olomouc implemented a unique research infrastructure for laser cooling of 40Ca+ ions and subsequent experiments of the quantum mechanics and spectroscopy in a joint laboratory in Brno. Currently 40Ca+ ions are routinely generated and captured. The Doppler cooling of those ions is performed using dipole transition at a wavelength of the 397 nm. Also detection and spectroscopy of the electronic structure of the ion and the presence of his dark resonances is implemented.\n
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Thin Photoresponding Elements with Frequency and Amplitude Modulations
Klusoň, Petr ; Morozová, Magdalena ; Dzik, P. ; Veselý, M.
Nanoscale templated metal oxide thin films undoubtedly appertain to the most extensively studied materials due to their optical and electrochemical properties. Their photo-induced properties arise from the semiconductor nature, especially from the ability of the light quantum absorption followed by the charge carrier generation. In order to produce metal oxide thin layer layers, the liquid sol containing also the templating bodies, and confining nanoparticles, must be coated onto a substrate. Various coating techniques have been used for this purpose, such as dip-, spin- or spraycoating. Recently a new promising deposition technique has appeared. The novel approach is usually termed piezoelectric jet material deposition or shortly material printing. In this case the ink is the specially formulated liquid purposed for transporting functional components onto the substrate surface. This technique brings the possibility of direct patterning, i.e. the fabrication of 2D patterns on the substrate without the need of any mechanical or optical masking. Material printing has been already employed for the deposition of variety functional materials.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22013102415160 - PDF
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Basic measurement techniques of the magnetic resonance
Toufarová, Tereza ; Bartušek, Karel (referee) ; Steinbauer, Miloslav (advisor)
This thesis deals with basic principles of magnetic resonance. It describes this phenomenon from the point of view of quantum mechanics and classic physics. Both approaches differ considerably, however, it is necessary to combine both to describe the phenomenon. The main focus of the thesis is analysis of individual measuring methods and their mutual comparison. The methods described are Spin-Echo Method, Saturation Recovery Technique, Inversion Recovery Technique and Grandient-Echo Method. This document contains a theoretical description of imaging techniques and processing of pictures gained by practical application of the methods.
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