Kronecker Product Correlation Model and Limited Feedback Codebook Design in a 3D Channel Model

A 2D antenna array introduces a new level of control and additional degrees of freedom in multiple-input-multiple-output (MIMO) systems particularly for the so-called "massive MIMO" systems. To accurately assess the performance gains of these large arrays, existing azimuth-only channel models have been extended to handle 3D channels by modeling both the elevation and azimuth dimensions. In this paper, we study the channel correlation matrix of a generic ray-based 3D channel model, and our analysis and simulation results demonstrate that the 3D correlation matrix can be well approximated by a Kronecker production of azimuth and elevation correlations. This finding lays the theoretical support for the usage of a product codebook for reduced complexity feedback from the receiver to the transmitter. We also present the design of a product codebook based on Grassmannian line packing.Comment: 6 pages, 5 figures, to appear at IEEE ICC 201

Náhodné mozaiky a jejich statistická analýza

Štatistickým aspektom náhodných mozaík nebolo v doterajšom výskume venované dostatočné množ- stvo pozornosti. Táto práca sa zaoberá odvodením odhadov a štatistických testov v modeli trojrozmer- ných Poissonových-Voronoiových mozaík. V prvej kapitole je zhromaždená základná teória bodových procesov, náhodných uzavretých množín a procesov častíc. Tie sa v druhej kapitole použijú na odvode- nie geometrických vlastností náhodných mozaík. Tretia kapitola približuje samotný štatistický výskum, odhady a testy modelu. Na korekciu štatistík napočítaných na zmenšenom výbere je zavedený Horvitzov- Thompsonov odhad. Vlastné výsledky sú overené počítačovou simuláciou aj porovnané s existujúcim výskumom v poslednej kapitole. Sledujeme prioritne kvalitu odhadov a silu navrhnutých testov. 1Statistical aspects of random mosaics have not been heretofore given enough attention. This thesis deals with the derivation of estimators and statistical tests in a three-dimensional Poisson-Voronoi mosaic model. The first chapter compiles elementary results in the fields of point processes, random closed sets and particle processes. These are used in a second chapter to deduce geometric properties of random mosaics. The third chapter introduces the statistical research itself, estimators and model tests. Horvitz- Thompson estimator is introduced in order to correct statistics calculated on a reduced sample. Own results are tried in a computer simulation and compared to existing research in the last chapter. Mainly, the quality of estimators and the power of proposed tests is observed. 1Department of Probability and Mathematical StatisticsKatedra pravděpodobnosti a matematické statistikyMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Statistické testy ve stratifikovaných čtyřpolních tabulkách

This paper deals with statistical tests in stratified fourfold tables. Several tests of conditional indepen- dence are derived in it. A test of homogeneous association is also described. At first, contingency tables with arbitrary dimensions and multinomial distribution are defined. Then we continue with a description of fourfold tables and their binomial representation. In the next section we deal with an odds ratio and its asymptotic distribution. Formal definition of stratification and relevant terms follows afterwards. In the next chapter a derivation of test statistics for conditional independence tests including the well-known Cochran-Mantel-Haenszel test based on a hypergeometric distribution can be found. This chapter also includes a description of Breslow-Day test of homogeneous association. A numerical simulation of chosen tests is performed eventually. 1Táto práca sa zaoberá štatistickými testami v stratifikovaných štvorpoľných tabuľkách. Je v nej od- vodených viacero testov podmienenej nezávislosti. Opísaný je aj test homogénnej asociácie. Najprv sú zavedené kontingenčné tabuľky ľubovoľných rozmerov a multinomické rozdelenie. Ďalej pokračujeme opi- som štvorpoľných tabuliek a ich binomickou reprezentáciou. V ďalšej časti sa zaoberáme pomerom šancí a jeho asymptotickým rozdelením. Potom nasleduje formálne zavedenie stratifikácie a súvisiacich pojmov. V ďalšej kapitole sa nachádza odvodenie testových štatistík pre testy podmienenej nezávislosti vrátane známeho Cochran-Mantel-Haenszelovho testu založeného na hypergeometrickom rozdelení. Kapitola tiež obsahuje popis Breslowovho-Dayovho testu homogénnej asociácie. Na záver je prevedená numerická si- mulácia vybraných testov. 1Katedra pravděpodobnosti a matematické statistikyDepartment of Probability and Mathematical StatisticsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

The Dependence of Work Function on Thickness in Epitaxial Cu-Pd Systems

Changes in work function have been measured with a Kelvin probe for the initial stages of epitaxial growth of (111) Cu on (111) Pd and (111) Pd on (111) Cu and for CO adsorption on selected bilayers at room temperature. The results of this study show that, at low metal coverages, the overlayers have properties which differ significantly from those of bulk crystals. One of the most interesting observations was that a quarter monolayer of Cu on Pd (111) increases the saturation work function change upon CO adsorption by more than a factor of three as compared to a thick Pd (111) film

Misfit dislocations in (111) Pd/(111) Cu bilayers

Misfit dislocations in the early stage of epitaxial growth of Pd on Cu at 25/sup 0/C were studied. Three different kinds of misfits dislocations were observed and their Burgers vector were determined. (FS

Análisis estructural y modal de las placas adaptación para martillos hidráulicos y minicargadores en condiciones reales de operación

En Perú, la necesidad de proyectos de servicios como la instalación de redes de gas para los residentes, ha incrementado la demanda del uso de martillos hidráulicos (HH) con cargadores compactos debido a la baja inversión en comparación con otros equipos de maquinaria y la versatilidad. La facilidad para intercambiar martillos hidráulicos con cucharones para completar las etapas de demolición y limpieza ofrecen para los contratistas una alta productividad en comparación con una operación manual. Por esa razón, el software de diseño virtual Inventor Professional fue usado para diseñar una placa de adaptación con la resistencia y durabilidad adecuadas, lo cual tiene un impacto directo sobre la estructura del martillo hidráulico y el brazo hidráulico del cargador compacto. Simultáneamente, se desarrolló una animación básica para explicar el efecto del estilo de operación sobre los martillos hidráulicos y las placas de adaptación. Finalmente, para este desarrollo, se consideró la construcción de la placa de adaptación como un fusible en el sistema, en caso de que los operadores excedan la capacidad de resistencia de la estructura del martillo hidráulico.//In Perú the need for utility projects such as gas network installation for residents has increased the demand for the use of Hydraulic Hammers (HH) with mini-loaders, due to the low investment required compared to other machinery equipment and to the versatility. The easiness to interchange hydraulic hammers with buckets to complete the demolition and cleaning stages offers for contractors a higher productivity than manual operations. For that reason, the virtual design software Inventor Professional was used to design a suitable adapter plate with adequate resistance and durability, which has a direct impact on the structure of the hydraulic hammer and the hydraulic arm of the skid steers. Simultaneously, a basic animation was developed to explain the effect of the operation style over the hydraulic hammers and the adapter plates. Finally, for this development, it was considered the construction of an adapter plate as a fuse in the system, in case operators exceed the resistance capacity of the hydraulic hammer structure

Análisis estructural y modal de las placas adaptación para martillos hidráulicos y minicargadores en condiciones reales de operación

In Perú the necessity of facility projects such as gas line installation for residents has increased the demand for use of Hydraulic Hammers (HH) with Skid Steers due to the lower amount of investment needed in comparison to other packs of machinery and the versatility. The ability to interchange hydraulic hammers and buckets to complete the demolition and cleaning stages offers higher productivity than manual operations for contractors. For that reason, the virtual design software Inventor Professional was used to design a suitable adapter plate with adequate resistance and durability which has a direct impact on the structure of the hydraulic hammer and the hydraulic arm of the skid steers. Simultaneously, a basic animation was developed to explain the effect of the operation style over the hydraulic hammer and the adapter plate. Finally, for this development, the construction of an adapter plate as a fuse in the system was considered in case operators exceed the resistance capacity of the hydraulic hammer structure.En Perú la necesidad de proyectos de servicios como la instalación de redes de gas para los residentes ha incrementado la demanda del uso de martillos hidráulicos (HH) con minicargadores debido a la baja inversión en comparación con otros equipos de maquinaria y la versatilidad. La facilidad para intercambiar martillos hidráulicos con cucharones para completar las etapas de demolición y limpieza ofrecen una alta productividad en comparación con una operación manual para los contratistas. Por esa razón, el software de diseño virtual Inventor Professional fue usado para diseñar una placa de adaptación con la resistencia y durabilidad adecuadas lo cual tiene un impacto directo sobre la estructura del martillo hidráulico y el brazo hidráulico del minicargador. Simultáneamente, se desarrolló una animación básica para explicar el efecto del estilo de operación sobre los martillos hidráulicos y las placas de adaptación. Finalmente, para este desarrollo, se consideró la construcción de la placa de adaptación como un fusible en el sistema en caso de que los operadores excedan la capacidad de resistencia de la estructura del martillo hidráulico

Electromigration-Induced Flow of Islands and Voids on the Cu(001) Surface

Electromigration-induced flow of islands and voids on the Cu(001) surface is studied at the atomic scale. The basic drift mechanisms are identified using a complete set of energy barriers for adatom hopping on the Cu(001) surface, combined with kinetic Monte Carlo simulations. The energy barriers are calculated by the embedded atom method, and parameterized using a simple model. The dependence of the flow on the temperature, the size of the clusters, and the strength of the applied field is obtained. For both islands and voids it is found that edge diffusion is the dominant mass-transport mechanism. The rate limiting steps are identified. For both islands and voids they involve detachment of atoms from corners into the adjacent edge. The energy barriers for these moves are found to be in good agreement with the activation energy for island/void drift obtained from Arrhenius analysis of the simulation results. The relevance of the results to other FCC(001) metal surfaces and their experimental implications are discussed.Comment: 9 pages, 13 ps figure

An in situ transmission electron microscopy study of the ion irradiation induced amorphisation of silicon by He and Xe

Transmission electron microscopy with in situ ion irradiation has been used to examine the ionbeam-induced amorphisation of crystalline silicon under irradiation with light (He) and heavy (Xe) ions at room temperature. Analysis of the electron diffraction data reveal the heterogeneous amorphisation mechanism to be dominant in both cases. The differences in the amorphisation curves are discussed in terms of intra-cascade dynamic recovery, and the role of electronic and nuclear loss mechanisms