Melting equipment in foundries

Cílem této bakalářské práce je popis vlastností a chod vybraných tavících agregátů ve slévárnách. Stručně byla popsána historie zpracování kovů a vývoj tavících agregátů. Na základě poznatků bylo provedeno rozdělení tavících systémů používaných ve slévárenské praxi a u jednotlivých systémů byly popsány jejich výhody, nevýhody a použití. Na závěr byly tavící agregáty zhodnoceny z technicko - ekonomického hlediska.The aim of this Bachelor thesis is a description of the properties and operation of selected melting equipment in foundries. History of metal processing and development of melting equipment are briefly described. Based on the findings, smeltering systems used in foundry practice were classified and the individual systems were described in terms of their advantages, disadvantages and application. At the end of thesis, melting equipment was assessed from technical-economic point of view.

Parameterized Approximation Schemes for Steiner Trees with Small Number of Steiner Vertices

We study the Steiner Tree problem, in which a set of terminal vertices needs to be connected in the cheapest possible way in an edge-weighted graph. This problem has been extensively studied from the viewpoint of approximation and also parametrization. In particular, on one hand Steiner Tree is known to be APX-hard, and W[2]-hard on the other, if parameterized by the number of non-terminals (Steiner vertices) in the optimum solution. In contrast to this we give an efficient parameterized approximation scheme (EPAS), which circumvents both hardness results. Moreover, our methods imply the existence of a polynomial size approximate kernelization scheme (PSAKS) for the considered parameter. We further study the parameterized approximability of other variants of Steiner Tree, such as Directed Steiner Tree and Steiner Forest. For neither of these an EPAS is likely to exist for the studied parameter: for Steiner Forest an easy observation shows that the problem is APX-hard, even if the input graph contains no Steiner vertices. For Directed Steiner Tree we prove that approximating within any function of the studied parameter is W[1]-hard. Nevertheless, we show that an EPAS exists for Unweighted Directed Steiner Tree, but a PSAKS does not. We also prove that there is an EPAS and a PSAKS for Steiner Forest if in addition to the number of Steiner vertices, the number of connected components of an optimal solution is considered to be a parameter.Comment: 23 pages, 6 figures An extended abstract appeared in proceedings of STACS 201

Influence of location of Al castings in a heat treatment furnace on mechanical properties

Tato diplomová práce se zabývá umístěním hliníkových odlitků v peci tepelného zpracování a jeho vlivem na mechanické vlastnosti. Jako zkušební vzorky se pro experimentální část použily tahové tyčky, které byly odlity z podeutektického siluminu AlSi7Mg0,6. Tyto vzorky se v peci uložily do míst, kde byly teploty kalibrovány dodavatelem pece. Následně se provedly tahové zkoušky k vyhodnocení jejich výsledných mechanických vlastností. Experiment proběhl ve slévárně neželezných kovů MESIT foundry, a.s. v Uherském Hradišti.The present Master thesis deals with location of aluminium castings in the heat treatment furnace and its influence on mechanical properties. As testing samples for the experimental part, tensile bars were used; they were cast from the subeutetic silumin AlSi7Mg0,6. These samples were placed in the furnace in the locations where temperatures were calibrated by the furnace supplier. Then, tensile tests were performed to evaluate the resulting mechanical properties of the samples. The experiment was carried out in the foundry of non-ferrous metals, MESIT foundry Ltd., Uherské Hradiště.

Simplified Algorithmic Metatheorems Beyond MSO: Treewidth and Neighborhood Diversity

This paper settles the computational complexity of model checking of several extensions of the monadic second order (MSO) logic on two classes of graphs: graphs of bounded treewidth and graphs of bounded neighborhood diversity. A classical theorem of Courcelle states that any graph property definable in MSO is decidable in linear time on graphs of bounded treewidth. Algorithmic metatheorems like Courcelle's serve to generalize known positive results on various graph classes. We explore and extend three previously studied MSO extensions: global and local cardinality constraints (CardMSO and MSO-LCC) and optimizing the fair objective function (fairMSO). First, we show how these extensions of MSO relate to each other in their expressive power. Furthermore, we highlight a certain "linearity" of some of the newly introduced extensions which turns out to play an important role. Second, we provide parameterized algorithm for the aforementioned structural parameters. On the side of neighborhood diversity, we show that combining the linear variants of local and global cardinality constraints is possible while keeping the linear (FPT) runtime but removing linearity of either makes this impossible. Moreover, we provide a polynomial time (XP) algorithm for the most powerful of studied extensions, i.e. the combination of global and local constraints. Furthermore, we show a polynomial time (XP) algorithm on graphs of bounded treewidth for the same extension. In addition, we propose a general procedure of deriving XP algorithms on graphs on bounded treewidth via formulation as Constraint Satisfaction Problems (CSP). This shows an alternate approach as compared to standard dynamic programming formulations

Incorporation of Low Concentrations of Gold Nanoparticles: Complex Effects on Radiation Response and Fate of Cancer Cells

(1) Background: In oncology research, a long-standing discussion exists about pros and cons of metal nanoparticle-enhanced radiotherapy and real mechanisms behind the tumor cell response to irradiation (IR) in presence of gold nanoparticles (GNPs). A better understanding of this response is, however, necessary to develop more efficient and safety nanoparticle (NP) types designed to disturb specific processes in tumor cells. (2) Aims and Methods: We combined 3D confocal microscopy and super-resolution single molecule localization microscopy (SMLM) to analyze, at the multiscale, the early and late effects of 10 nm-GNPs on DNA double strand break (DSB) induction and repair in tumor cells exposed to different doses of photonic low-LET (linear energy transfer) radiation. The results were correlated to different aspects of short and long-term cell viability. SkBr3 breast cancer cells (selected for the highest incidence of this cancer type among all cancers in women, and because most breast tumors are treated with IR) were incubated with low concentrations of GNPs and irradiated with Co-60 gamma-rays or 6 MV X-rays. In numerous post-irradiation (PI) times, ranging from 0.5 to 24 h PI, the cells were spatially (3D) fixed and labeled with specific antibodies against gamma H2AX, 53BP1 and H3K9me3. The extent of DSB induction, multi-parametric micro- and nano-morphology of gamma H2AX and 53BP1 repair foci, DSB repair kinetics, persistence of unrepaired DSBs, nanoscale clustering of gamma H2AX and nanoscale (hetero)chromatin re-organization were measured by means of the mentioned microscopy techniques in dependence of radiation dose and GNP concentration. (3) Results: The number of gamma H2AX/53BP1 signals increased after IR and an additional increase was observed in GNP-treated (GNP(+)) cells compared to untreated controls. However, this phenomenon reflected slight expansion of the G2-phase cell subpopulation in irradiated GNP(+) specimens instead of enhanced DNA damage induction by GNPs. This statement is further supported by some micro- and nano-morphological parameters of gamma H2AX/53BP1 foci, which slightly differed for cells irradiated in absence or presence of GNPs. At the nanoscale, Ripley's distance frequency analysis of SMLM signal coordinate matrices also revealed relaxation of heterochromatin (H3K9me3) clusters upon IR. These changes were more prominent in presence of GNPs. The slight expansion of radiosensitive G2 cells correlated with mostly insignificant but systematic decrease in post-irradiation survival of GNP(+) cells. Interestingly, low GNP concentrations accelerated DSB repair kinetics; however, the numbers of persistent gamma H2AX/53BP1 repair foci were slightly increased in GNP(+) cells. (4) Conclusions: Low concentrations of 10-nm GNPs enhanced the G2/M cell cycle arrest and the proportion of radiosensitive G2 cells, but not the extent of DNA damage induction. GNPs also accelerated DSB repair kinetics and slightly increased presence of unrepaired gamma H2AX/53BP1 foci at 24 h PI. GNP-mediated cell effects correlated with slight radiosensitization of GNP(+) specimens, significant only for the highest radiation dose tested (4 Gy)

Tomaszewski's conjecture

In 1986, Boguslaw Tomaszewski asked the following question: Consider n real numbers a1, . . . , an such that the sum of their squares is 1. Of the 2n expressions |ε1a1 + · · · + εnan| with εi = ±1, can there be more with value > 1 than with value ≤ 1? Apart from being of intrinsic interest in probability, an answer to this conjecture would also have applications in quadratic programming. However, even after more than thirty years the conjecture is still unsolved. In this thesis we settle a special case of the conjecture - we prove that the conjecture holds for vectors of the form (α, δ, . . . , δ) of sufficiently large dimension. This generalizes earlier result which showed that the conjecture holds for vectors of the form (δ, . . . , δ).

Pull-out body of towing vehicle for car transport

Diplomová práce obsahuje přehled nástaveb pro odtah osobních automobilů, návrh a koncepce nástaveb. Vytvoření modelu v CAD, výpočtové ověření modelu.Katedra konstruování strojůObhájenoThe diploma´s thesis contains a summary of extensions for towing cars design and concept of extensions, 3D model created in CAD system and computational verification of mode

Algoritmické metavěty pro matroidy

V práci definujeme nový šířkový parametr pro matroidy nazvaný amal- gamační šířka. Tento šířkový parametr vychází z operace amalgamace ma- troidů. Parametr má úzký vztah k větvící šířce (branch width) na matroidech reprezentovatelných nad pevně zvoleným konečným tělesem - reprezento- vatelné matroidy s omezenou větvící šířkou mají omezenou i amalgamační šířku. Přitom jsme stále schopni rozhodovat vlastnosti v monadické log- ice druhého řádu v lineárním čase pro matroidy s omezenou amalgamační šířkou a to i tehdy, když matroid není reprezentovatelný (pokud ovšem máme dekompozici danou). Navíc dokážeme spočíst koeficienty Tutteho polynomu matroidu v polynomiálním čase na třídách matroidů s omezenou amalgamační šířkou.In the thesis we define a new width parameter for matroids called amal- gam width that is based on the operation of matroid amalgamation. The parameter is related to branch width for matroids representable over fixed fi- nite field in the sense that class of representable matroids of bounded branch width has bounded amalgam width. The decomposition allows us to decide monadic second-order properties in linear time on matroids of bounded amal- gam width, even for matroids that are not representable (provided we are given the decomposition). We also prove that the coefficients of the Tutte polynomial can be computed in polynomial time for matroids of bounded amalgam width.Computer Science Institute of Charles UniversityInformatický ústav Univerzity KarlovyMatematicko-fyzikální fakultaFaculty of Mathematics and Physic