|
|
Temperature measurements with thermocouples
Hyrš, Jan ; Kandus, Bohumil (referee) ; Podaný, Kamil (advisor)
The work is aimed at measuring temperature with thermocouples. Brief is made introduction to its basic measurement and distribution. The principle function of the thermocouple is explained, and also describes its basic properties. The paper also described how they integrated into a circuit. Performed an overview of the use of thermocouples in practice, indicating illustrative examples. In conclusion, it is processed and evaluated executed experiment temperature of hotplate´s stove.
|
|
|
AB INITIO STUDY OF SILVER NANOPARTICLES, GRAIN BOUNDARIES AND THEIR \nQUADRUPLE JUNCTIONS
Polsterová, S. ; Všianská, Monika ; Friák, Martin ; Pizúrová, Naděžda ; Sokovnin, S. ; Šob, Mojmír
Motivated by our experimental research related to silver nanoparticles with various morphologies, we have employed quantum-mechanical calculations to provide our experiments with theoretical insight. We have computed properties of a 181-atom decahedral silver nanoparticle and two types of internal extended defects, -5(210) grain boundaries (GBs) and quadruple junctions (QJs) of these GBs. We have employed a supercell approach with periodic boundary conditions. Regarding the thermodynamic stability of the decahedral nanoparticle, its energy is higher than that of a defect-free face-centered cubic (fcc) Ag by 0.34 eV/atom. As far as the -5(210) GB is concerned, its energy amounts to 0.7 J/m2 and we predict that the studied GBs would locally expand the volume of the lattice. Importantly, the system with GBs is found rather close to the limit of mechanical stability. In particular, the computed value of the shear-related elastic constant C66 is as low as 9.4 GPa with the zero/negative value representing a mechanically unstable system. We thus predict that the -5(210) GBs may be prone to failure due to specific shearing deformation modes. The studied GBs have also the value of Poisson’s ratio for some loading directions close to zero. Next, we compare our results related solely to -5(210) GBs with those of a system where multiple intersecting -5(210) GBs form a network of quadruple junctions. The value of the critical elastic constant C66 is higher in this case, 13 GPa, and the mechanical stability is, therefore, better in the system with QJs.
|
|
|
Numerical solution of traffic flow models
Vacek, Lukáš ; Kučera, Václav (advisor)
Our work describes the simulation of traffic flows on networks. These are described by partial differential equations. For the numerical solution of our models, we use the discontinuous Galerkin method in space and a multistep method in time. This combination of the two methods on networks is unique and leads to a robust numerical scheme. We use several different approaches to model the traffic flow. Thus, our program must solve both scalar problems as well as systems of equations described by first and second order partial differential equations. The output of our programs is, among other things, the evolution of traffic density in time and 1D space. Since this is a physical quantity, we introduce limiters which keep the density in an admissible interval. Moreover, limiters prevent spurious oscillations in the numerical solution. All the above is performed on networks. Thus, we must deal with the situation at the junctions, which is not standard. The main task is to ensure that the law of conservation of the total amount of cars passing through the junction is still satisfied. This is achieved by modifying the numerical flux for junctions. The result of this work is the comparison of all the models, the demonstration of the benefits of the discontinuous Galerkin method and the influence of limiters.
|
|
|
Numerical solution of traffic flow models
Vacek, Lukáš ; Kučera, Václav (advisor)
Our work describes the simulation of traffic flows on networks. These are described by partial differential equations. For the numerical solution of our models, we use the discontinuous Galerkin method in space and a multistep method in time. This combination of the two methods on networks is unique and leads to a robust numerical scheme. We use several different approaches to model the traffic flow. Thus, our program must solve both scalar problems as well as systems of equations described by first and second order partial differential equations. The output of our programs is, among other things, the evolution of traffic density in time and 1D space. Since this is a physical quantity, we introduce limiters which keep the density in an admissible interval. Moreover, limiters prevent spurious oscillations in the numerical solution. All the above is performed on networks. Thus, we must deal with the situation at the junctions, which is not standard. The main task is to ensure that the law of conservation of the total amount of cars passing through the junction is still satisfied. This is achieved by modifying the numerical flux for junctions. The result of this work is the comparison of all the models, the demonstration of the benefits of the discontinuous Galerkin method and the influence of limiters.
|
|
|
Temperature measurements with thermocouples
Hyrš, Jan ; Kandus, Bohumil (referee) ; Podaný, Kamil (advisor)
The work is aimed at measuring temperature with thermocouples. Brief is made introduction to its basic measurement and distribution. The principle function of the thermocouple is explained, and also describes its basic properties. The paper also described how they integrated into a circuit. Performed an overview of the use of thermocouples in practice, indicating illustrative examples. In conclusion, it is processed and evaluated executed experiment temperature of hotplate´s stove.
|
guest ::
