Social Desktop

Tato bakalářská práce se zabývá tématem sociálních sítí a jejich vlivem na každodenní používaní osobního počítače. Představuje projekt KDE Silk, který se snaží webové služby do prostředí pracovní plochy integrovat a práci nejen se sociálními sítěmi zjednodušit. V rámci vlastní práce je představen doplněk pro KDE Plasmu - Geoweb, který je implementován jako součást projektu KDE Silk. Geoweb slouží na správu aktuální polohy uživatele s přidanými informacemi relevantními k této poloze. Druhy informací které Geoweb poskytuje, sou dostupné ve formě rozšíření.This Bachelor thesis describes problem of social networking and its influence to everyday usage of personal computers. It introduces project KDE Silk, which is integrating web services into workspace of desktop environment and making daily work not only with social networks easier and more pleasant. As practical part of this thesis is presented addon for KDE Plasma - Geoweb implemented as part of KDE Silk. Geoweb is used for managing actual user location with additional information relevant to the given position. Various types of information are provided as plugins for Geoweb.

PARSEC: A Parametrized Simulation Engine for Ultra-High Energy Cosmic Ray Protons

We present a new simulation engine for fast generation of ultra-high energy cosmic ray data based on parametrizations of common assumptions of UHECR origin and propagation. Implemented are deflections in unstructured turbulent extragalactic fields, energy losses for protons due to photo-pion production and electron-pair production, as well as effects from the expansion of the universe. Additionally, a simple model to estimate propagation effects from iron nuclei is included. Deflections in galactic magnetic fields are included using a matrix approach with precalculated lenses generated from backtracked cosmic rays. The PARSEC program is based on object oriented programming paradigms enabling users to extend the implemented models and is steerable with a graphical user interface.Comment: 10 pages, 6 figures, accepted for publication in Astroparticle Physic

A Method of Measuring Cosmic Magnetic Fields with Ultra High Energy Cosmic Ray Data

We present a method to measure cosmic magnetic fields with ultra high energy cosmic rays (UHECRs). We apply an advanced autocorrelation method to simulated UHECRs which includes their directional as well as energy information. Without explicit knowledge of the UHECR sources, such measurements are sensitive to the number of sources and to the magnetic field strength subjected to the UHECRs. Using a UHECR Monte Carlo model including sources, random walk propagation and a coherent deflection, we explain the procedure of reconstructing the allowed phase space of the model parameters from a simulated autocorrelation measurement.Comment: accepted at Astroparticle Physic

Colloquium: Artificial spin ice: Designing and imaging magnetic frustration

Frustration in the presence of competing interactions is ubiquitous in the physical sciences and is a source of degeneracy and disorder, giving rise to new and interesting physical phenomena. Perhaps nowhere does it occur more simply than in correlated spin systems, where it has been studied in the most detail. In the past few years, a new perspective has opened in the study of frustration through the creation of artificial frustrated magnetic systems. These materials consist of arrays of lithographically fabricated single-domain ferromagnetic nanostructures that behave like giant Ising spins. The nanostructures' interactions can be controlled through appropriate choices of their geometric properties and arrangement on a (frustrated) lattice. The degrees of freedom of the material can not only be directly tuned, but also individually observed. Experimental studies have unearthed intriguing connections to the out-of-equilibrium physics of disordered systems and non-thermal granular materials, while revealing strong analogies to (spin) ice materials and their fractionalized magnetic monopole excitations, lending the enterprise a distinctly interdisciplinary flavor. The experimental results have also been closely coupled to theoretical and computational analyses, facilitated by connections to classic models of frustrated magnetism, whose hitherto unobserved aspects have here found an experimental realization. We review the considerable experimental and theoretical progress in this field, including connections to other frustrated phenomena, and we outline future vistas for progress in this rapidly expanding field.Comment: Review Article, 36 Pages, 14 Figures. To appear in Rev. Mod. Phy

Magnetization states and switching in narrow-gapped ferromagnetic nanorings

We study permalloy nanorings that are lithographically fabricated with narrow gaps that break the rotational symmetry of the ring while retaining the vortex ground state, using both micromagnetic simulations and magnetic force microscopy (MFM). The vortex chirality in these structures can be readily set with an in-plane magnetic field and easily probed by MFM due to the field associated with the gap, suggesting such rings for possible applications in storage technologies. We find that the gapped ring edge characteristics (i.e., edge profile and gap shape) are critical in determining the magnetization switching field, thus elucidating an essential parameter in the controls of devices that might incorporate such structures

Aerodynamic Inner Workings of Circumferential Grooves in a Transonic Axial Compressor

The current paper reports on investigations of the fundamental flow mechanisms of circumferential grooves applied to a transonic axial compressor. Experimental results show that the compressor stall margin is significantly improved with the current set of circumferential grooves. The primary focus of the current investigation is to advance understanding of basic flow mechanics behind the observed improvement of stall margin. Experimental data and numerical simulations of a circumferential groove were analyzed in detail to unlock the inner workings of the circumferential grooves in the current transonic compressor rotor. A short length scale stall inception occurs when a large flow blockage is built on the pressure side of the blade near the leading edge and incoming flow spills over to the adjacent blade passage due to this blockage. The current study reveals that a large portion of this blockage is created by the tip clearance flow originating from 20% to 50% chord of the blade from the leading edge. Tip clearance flows originating from the leading edge up to 20% chord form a tip clearance core vortex and this tip clearance core vortex travels radially inward. The tip clearance flows originating from 20% to 50% chord travels over this tip clearance core vortex and reaches to the pressure side. This part of tip clearance flow is of low momentum as it is coming from the casing boundary layer and the blade suction surface boundary layer. The circumferential grooves disturb this part of the tip clearance flow close to the casing. Consequently the buildup of the induced vortex and the blockage near the pressure side of the passage is reduced. This is the main mechanism of the circumferential grooves that delays the formation of blockage near the pressure side of the passage and delays the onset of short length scale stall inception. The primary effect of the circumferential grooves is preventing local blockage near the pressure side of the blade leading edge that directly determines flow spillage around the leading edge. The circumferential grooves do not necessarily reduce the over all blockage built up at the rotor tip section

An Automatic Configuration of Services of Operating System

Tato diplomová práce se zabývá konfigurací operačních systémů, jejich možnostmi a způsoby nastavení. Představuje rozdíly v konfiguraci operačních systémů podle jejich zaměření a pokročilé možnosti konfigurace operačních systémů pomocí aplikací třetích stran. Praktická část diplomové práce se zabývá návrhem nového počítačového jazyka zaměřeného na popis konfigurace operačního systému a jeho služeb. Tento popis konfigurace sloužící na automatickou konfiguraci systémových služeb se překládá na sekvenci konfiguračních příkazů. Výhoda jazyka spočívá v jeho dobré čitelnosti pro člověka, ale podobnost s přirozeným jazykem přináší určitou úroveň nejednoznačnosti. Navrhovaná metoda automatického generování příkazů řeší nejednoznačnost vyhledáváním co nejméně destruktivního řešení v podobě kombinaci konfiguračních příkazů.This Master thesis describes the configuration of operating systems and their capabilities. It introduces differences between configuration of different operating systems according to their specialization, and it introduces advanced configuration of operating systems with third-party applications. The practical part of the thesis is a design of a new computer language aimed at describing a configuration of an operating system and its services. Such a description is used to automatically configure system services by translating it to a sequence of configuration commands. An advantage of the language is its readability by a human, but its similarity with natural languages introduces a certain level of ambiguity. The proposed method of automatic generation of commands deals with the ambiguity by searching and selecting as least as possible destructive commands.