Anomalous Hall effects and electron polarizability

A theory of the anomalous and spin Hall effects, based on the space distribution of the current densities, is presented. Spin-orbit coupling gives rise to a space separation of the mass centers, as well as a current density separation of the quasiparticle states having opposite group velocities. It is shown that this microscopic property is essential for existence of both Hall effects

Electron polarizability of crystalline solids in quantizing magnetic fields and topological gap numbers

A theory of the static electron polarizability of crystals whose energy spectrum is modified by quantizing magnetic fields is presented. It is argued that The polarizability is strongly affected by non-dissipative Hall currents induced by the presence of crossed electric and magnetic fields: these can even change its sign. Results are illustrated in detail for a two dimensional square lattice. The polarizability and the Hall conductivity are respectively linked to the two topological quantum numbers entering the so--called Diophantine equation. These numbers could in principle be detected in actual experiments

Use 8x8 LED Matrix and MEMS Sensor for Promotional Purposes

Hlavním cílem této bakalářská práce je vytvoření ukázkové aplikace pro propagační účely. Jedná se o využití mikrokontroléru ATmega32A, MEMS snímače zrychlení a úhlové rychlosti a 8x8 LED matice s řadičem. Práce je v teoretické části zaměřena na charakteristiku použitých součástek, jejich vlastností a způsobu řízení. Následně se práce zabývá napájením, návrhem a výrobou desky plošných spojů pro mikrokontrolér a v poslední části práce je pozornost věnována softwaru mikrokontroléru a výrobě pouzdra.The main objective of this bachelor thesis is to create exemplary application for promotional purposes. It means using of a microcontroller ATmega32A, a MEMS acceleration and angular velocity sensor and a LED matrix with a driver.. In the theoretical part the thesis is focused on the characteristics of used components, their features and way of control. Subsequently, the thesis deals with a power supply, design and manufacture of a printed circuit board for microcontroller and the last part of the thesis is focused on a microcontroller's software and manufacture of a casing.

Remote Control Submarine Robot

Tato práce se snaží zmapovat a stručně roztřídit rozsáhlý vývoj a využití podvodních robotů. Práce klade důraz především na roztřídění nových směrů vývoje, které se objevily relativně nedávno a dynamicky se rozvíjejí. Dále se zabývá porovnáním jednotlivých koncepcí. V závěru práce je shrnutí směřování budoucího vývoje a doporučení koncepce pro stavbu podvodního robota.This Bechelor thesis is trying to chart and briefly categorize extensive develepment and use of underwater robots. Bachelor thesis gives particular emphasis to classifying new trends which had emerged relatively recently and are developing dynamically. It also deals with comparison of concepts. The conclusion is a summary of the direction of future development and desing recommendations for building an underwater robot.

Inter-layer Hall effect in double quantum wells subject to in-plane magnetic fields

We report on a theoretical study of the transport properties of two coupled two-dimensional electron systems subject to in-plane magnetic fields. The charge redistribution in double wells induced by the Lorenz force in crossed electric and magnetic fields has been studied. We have found that the redistribution of the charge and the related inter-layer Hall effect originate in the chirality of diamagnetic currents and give a substantial contribution to the conductivity.Comment: 7 RevTex pages, 4 figures, appendix added and misprint in Eq. (11) correcte

Plant Integrity – The Important Factor of Adaptability to Stress Conditions

Crop production, research of crop productivity, tolerance to abiotic and biotic stresses, plant disease, and pests all represent the problem of plant integrity. Plants represent an integrated system of units, which are responsible for its resistance to adverse environmental conditions on the basis of the evaluation of characteristics both aboveground and in the roots. This "complete unit" (root and shoot) has an influence on the formation of seeds, the quality of which may affect subsequent growth, development, and stress tolerance of the filial generation. Properties of the roots predominantly influence (especially at drought stress conditions) growth, development, and the metabolic processes in the aboveground part of the plant. The seed traits affect the filial generation root morphology at the beginning of the vegetation period (especially length, surface, depth of root penetration, and also root weight). In the biology of the seeds, roots, yield formation, stress tolerance, etc., attention needs to be paid to plant integrity and adaptability during variable environmental conditions. Every plant, and its traits, is a result of all the plant’s activities. This is important for plant breeding. For example, it is possible to provide selection for cultivar traits at seed germination. Quality of the embryonic traits is important for subsequent growth and development. In the juvenile phase, and in later stages, the same genotype is still active. This is is among the main reasons for studying plant integrity

Longitudinal conductivity and transverse charge redistribution in coupled quantum wells subject to in-plane magnetic fields

In double quantum wells electrons experience a Lorentz force oriented perpendicular to the structure plane when an electric current is driven perpendicular to the direction of an in-plane magnetic field. Consequently, the excess charge is accumulated in one of the wells. The polarization of a bilayer electron system and the corresponding Hall voltage are shown to contribute substantially to the in-plane conductivity.Comment: 3 pages, 2 figure

Hall plateau diagram for the Hofstadter butterfly energy spectrum

We extensively study the localization and the quantum Hall effect in the Hofstadter butterfly, which emerges in a two-dimensional electron system with a weak two-dimensional periodic potential. We numerically calculate the Hall conductivity and the localization length for finite systems with the disorder in general magnetic fields, and estimate the energies of the extended levels in an infinite system. We obtain the Hall plateau diagram on the whole region of the Hofstadter butterfly, and propose a theory for the evolution of the plateau structure with increasing disorder. There we show that a subband with the Hall conductivity $n e^2/h$ has $|n|$ separated bunches of extended levels, at least for an integer $n \leq 2$. We also find that the clusters of the subbands with identical Hall conductivity, which repeatedly appear in the Hofstadter butterfly, have a similar localization property.Comment: 9 pages, 12 figure

Weak-field Hall effect and static polarizability of Bloch electrons

A theory of the weak field Hall effect of Bloch electrons based on the analysis of the forces acting on electrons is presented. It is argued that the electric current is composed of two contributions, that driven by the electric field along current flow and the non-dissipative contribution originated in demagnetization currents. The Hall resistance as a function of the electron concentration for the tight-binding model of a crystal with square lattice and body-centered cubic lattice is described in detail. For comparison the effect of strong magnetic fields is also discussed

Using RPAS for monitoring agricultural fields

Multispektrální data, obzvláště pak z červené a blízké infračervené spektrální oblasti, prokázala svůj význam při detekci vegetace v aplikacích dálkového průzkumu Země. V~současné době je těchto poznatků využíváno v oboru precizního zemědělství. Využívání běžných digitálních kamer a RPAS systémů vede ke vzniku rušivých vlivů v~obraze. Cíl práce je zaměřen na vyhodnocení postupu pořízení a zpracování snímků s využitím sestavy klasického fotoaparátu a infrafotoaparátu. Za tímto účelem bylo s využitím jednoduché RPAS sestavy pořízeno několik testovacích snímků na výzkumném poli. Z pořízených snímků byla vytvořena ortofota a s použitím vegetačního indexu byl otestován vliv na detekci vegetace. Z výsledků testování byly navrhnuty doporučené postupy zpracování.Multispectral data, especially from the red and near-infrared spectral region, have their importance in detecting vegetation in remote sensing applications. At present, this knowledge is used in precision farming. The use of common digital cameras and RPAS systems results in disturbing effects in the image. The aim of this work is to evaluate the procedure of acquisition and processing of images using a classical camera and infrared camera assembly. For this purpose, a number of test images were taken in the research field using several RPAS assemblies. The orthophoto was made from the captured images and the effect on vegetation detection was tested using the vegetation index. From the test results have been suggested recommended practices