|
| |
|
|
Studium elektromagnetických emisí pozorovaných družicí DEMETER
Píša, David ; Santolík, Ondřej (advisor) ; Shklyar, David R. (referee) ; Souček, Jan (referee)
David PÍŠA Study of electromagnetic emissions recorded by the DEMETER satellite Abstract : This thesis presents results based on wave measurements performed by the DEMETER space- craft. This French spacecraft was operating between 2004 and 2010 at the altitude of ∼660 km. We focus on measurements of the electromagnetic waves and plasma density in the vicinity of imminent earthquakes. In the first part, we present a study of plasma density variations in the vicinity of a very powerful earthquake in Chile (Mw 8.8) which occurred on February 27, 2010. Data recorded before the main shock along orbits close to the future epicenter showed increasing plasma den- sities. A statistical analysis using 4 years of data to monitor density variations under similar conditions has been performed. This study shows that a large increase of the plasma density is very uncommon at this location. In the second part, a statistical study (∼6.5 years) of variations of VLF wave intensity is shown. We have analyzed all available data measured close (in time and space) to large earth- quakes (M≥5). Data related to more than 12000 earthquakes have been compared with an unperturbed background distribution. We confirm the previously reported results of a statis- tically significant decrease of the wave intensity at frequencies of about...
|
|
|
Modeling of Signal Propagation in Wireless LTE and WiFi Networks in Indoor Deployment
Olbert, Jaroslav ; Mašek, Pavel (referee) ; Hošek, Jiří (advisor)
Masters thessis deals with the problematics of wireless signal propagation modeling inside buildings. The theoretical part of this thessis describes principles and methods of electromagnetic waves spreading in open areas and in indoor deployment. There are also described methods used for calculating the path of signal propagation ray-launching and ray-tracing. This part also includes description of an algorithm and equations used for simulating 5GHz WiFi signal propagation inside the Department of telecommunications corridors. Second part of this thessis includes a description of a NS-3 module mmWave, which was used for simulations of IEEE 802.11ad (WiGig) standard. There are also results of these simulations and their detailed description. At the end of this thessis comparison of these results with values gained by real environment measurements can be found.
|
|
|
A Brief Design of Optical Resonators
Hubík, Daniel ; Nešpor, Dušan (referee) ; Kadlec, Radim (advisor)
This bachelor thesis is focused on analysis of split-ring resonators in THz region. Simulations were made by finite elements method and by finite-difference time-domain method. At first we created a resonating structure that works in GHz region. Then we were observing a dependence of movement of resonant frequency on the size of resonator. In the final chapter we assigned frequency dependent values of permitivity to such structure. As the result we simulated working resonator at frequency 500THz. All simulations have been made in program HFSS ANSYS and Lumerical FDTD Solutions.
|
|
|
Vectorial Kerr magnetometry
Flajšman, Lukáš ; Veis,, Martin (referee) ; Urbánek, Michal (advisor)
Increased complexity of novel magnetic materials in the last decade has placed high demands on the manufacturing process as well as on the characterization. One of the possibilities for characterization of magnetic samples is to exploit the magneto-optical effects. The presented work uses the magneto-optical Kerr effect as a major characterization technique to probe the magnetic properties of samples. We have developed a mathematical model describing the effect of the magnetization on the polarized light and present an apparatus capable of measuring the response given by the light-matter interaction. The experimental results show the performance of the apparatus on the various magnetic systems including meta-stable iron layers, Stoner-Wohlfarth particles and magnetic vortices. The scanning vectorial Kerr magnetometer allowed us to probe the vector of magnetization with diffraction limited resolution below 500 nm.
|
|
|
Accuracy of non-contacting Temperature Measurement
Horák, Ladislav ; Janečka, Jan (referee) ; Vdoleček, František (advisor)
This master’s thesis is specialized on the influence of correct parameters of emissivity, which depends on the temperature, wavelength and ambient environment. The investigation the parameter was taken infrared non-contact thermometer MI3 from company Raytek. To improve the quality of measurement was designed and programmed measuring utility program. The program was developed in the LabView 8.5 programming environment. To obtain the true value of the measured temperature of the target was designed and constructed the touch thermometer with the resistance dependent sensor. The thermometer is connected to the communication box of infrared thermometer and contain the same program. Nowadays are the most advanced IR thermometer with fixed parameters emissivity, which is applicable just to the real body in the vicinity of the parameter emissivity 0,95. For those IR thermometers were designed correction function, which would have temperature measured at a fixed emissivity parameter 0,95 set close to the actual value of the object.
|
guest ::
