National Repository of Grey Literature 19 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
Modeling of nanofibers interaction with the environment
Klicmanová, I. ; Sveshnikov, Alexey
Nanomaterials change our life. Every day they find applications in new branches of technology. At the same time, some branches of technology, like civil engineering, are rather conservative and do not accept new approaches lightly. Nanotextiles exhibit a number of qualities that make them a promising material for civil engineering applications. They can potentially play a role of filters, protective layers, armature and others. Properties of the nanotextiles can be significantly influenced by parameters of technological process. Pure experimental search of the optimal technological parameters to achieve the desired properties of the final material can be very tedious. Thus, a theoretical dependence of the properties of the nanotextile on parameters of the technological process must be established. Two independent tasks must be solved for this: the dependence of nanotextile structure on technological parameters, and determination of physical, chemical or biological properties of a nanotextile of a given structure. In this paper we discuss steps necessary for the solution of the second task.
Initial study of structure of nanofiber textiles and the creation of its model
Havrlík, M. ; Sveshnikov, Alexey
In this research, the structure of the fabrics was analyzed using an electron scanning microscope Tescan Maia 3. Two sets of the experiments have been carried out. In the first experiment the surface structure of the samples was studied. Photos created by SEM were analyzed using program Atlas and image editor GIMP. In this set of the experiments the initial parameters for the creation of a digital 2D model of a single layer have been determined (fiber size distribution, pore size and curvature of the fibers). In the second set of the experiments cross sections of nanofiber textiles were made in order to study the inner structure of the fabric. This information allows evaluation of the total number of 2D layers in the model and, thus, is very important for future creation of a 3D model of the fabric.
General methodology for high temperature processes of semiconductor technology by the finite element methods
Jirásek, Vít ; Potocký, Štěpán ; Sveshnikov, Alexey
A general methodology for modeling of high-temperature reactors produced by SVCS Process Innovation, Ltd., using the finite element, resp. finite volume method, was developed. The methodology covers basics principles of working with SW packages for CFD modeling with the emphasis on the strongly coupled processes of chemically reacting fluid flow, mass and heat transport. An important part is devoted to the model-experiment relationship, verification and validation of models and comparison with experiments.
Kinetics of formation of crystalline nuclei on active centers
Kožíšek, Zdeněk ; Demo, Pavel ; Sveshnikov, Alexey
Nucleation on active centers is studied. We suggested new model: depletion of active centers is taken into account through boundary condition and thus no additional equation is needed in contrary to standard model. Our model describes corectly not only the total number of nuclei, but also nucleation rate and the size distribution of nuclei.
Equilibrium shape of a liquid nucleus on a highly curved surface of a nanofiber
Sveshnikov, Alexey ; Demo, Pavel ; Kožíšek, Zdeněk
Approximate equilibrium shape of a liquid nucleus on a nanofiber was determined by minimalization of its free energy under condition of the constant volume of the nucleus. The nucleus is stretched in the direction parallel to the nanofiber axis. The deviation of the shape from a sphere is larger for well-wetting cases.
Volumic dependence of nucleation barrier at critical supersaturation
Kožíšek, Zdeněk ; Demo, Pavel ; Sveshnikov, Alexey
Kinetic equations of nucleation are solved numerically to found conditions, under which first nuclei are formed. Critical supercooling is determined from the size distribution of nuclei. It is shown that nucleation barrier at critical supercooling depends logarithmically on droplet volume.
Thermal properties and crystallization kinetics of Er:LiY(PO.sub.3./sub.).sub.4./sub. glass
Rodová, Miroslava ; Cihlář, Antonín ; Král, Robert ; Sveshnikov, Alexey ; Nitsch, Karel
This contribution deals with study on thermal properties of phosphate glass with a nominal composition of Er:LiY(PO3)4 when searching new scintillation glasses.
Kinetics of polymer nucleation on active centers
Kožíšek, Zdeněk ; Demo, Pavel ; Sveshnikov, Alexey ; Tichá, Petra
We have numerically solved kinetic equations describing formation of nuclei on active centers to determine the total number of nuclei, nucleation rate and the number densities of nuclei near critical size. Results of our model were compared with experimental data for polymer crystal nucleation of polyethylene on nucleation agent. Our model predicts are in good coincidence with experimental data.
Analysis of crystallization kinetics of Li-Y phosphate glass under non-isothermal conditions
Nitsch, Karel ; Rodová, Miroslava ; Sveshnikov, Alexey
Crystallization kinetics of erbium doped LiY(PO3)4 glass was studied experimentally using DSC under non-isothermal conditions. Based on the experimental data the applicability of Johnson-Mehl-Avrami model was tested for description of crystallization kinetics of above mentioned glass.
Kritická přesycení v malých objemech
Kožíšek, Zdeněk ; Demo, Pavel ; Sveshnikov, Alexey
Critical supersaturation is derived from the size distribution of nuclei as a function of volume of mother phase.

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