National Repository of Grey Literature 111 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Powder Metallurgy of Hybrid Materials for Advanced Applications
Kozlík, Jiří ; Stráský, Josef (advisor) ; Kim, Hyoung Seop (referee) ; Novák, Pavel (referee)
Powder Metallurgy of Hybrid Materials for Advanced Applications The field-assisted sintering technology (FAST) is a versatile powder consolidation method, which uses electrical current for rapid heating of the sintered material. It is routinely used for sintering of various metallic materials, but mostly with preal- loyed powders as a feedstock. The aim of the thesis is to explore the capabilities of FAST for sintering of composite materials and for using blended elemental powders as a raw material in following areas: 1. Manufacturing of architectured composites 2. Consolidation and ageing in a single processing run (in-situ ageing) 3. Rapid alloy prototyping using blended elemental powders 4. High-throughput experimental investigations of multicomponent phase dia- grams Al6061 + Ti-6Al-4V architectured composite was produced, but issues with the pow- der penetration into the lattice have arisen due to the small lattice dimensions. Me- chanical properties could have been assessed by a three-point bending only. The composite has shown improved strength over the plain, unannealed Al6061 matrix, but a premature fracture when the Al matrix was aged properly. Using FAST was found to be inconvenient for architectured composite manufacturing. A long, fully dense rod was manufactured from the Ti-5Al-5V-5Mo-3Cr...
GRAIL and LOLA Satellite Data Resolve the Long-Lasting Convergence/Divergence Problem for the Analytical Downward Continuation of the External Spherical Harmonic Expansions
Šprlák, Michal ; Han, Shin-Chan ; Pitoňák, Martin ; Novák, Pavel
Spherical harmonic expansions are routinely used to represent the gravitational potential and its higherorder spatial derivatives in global geodetic, geophysical, and planetary science applications. The convergence domain of external spherical harmonic expansions is the space outside the minimum Brillouin sphere (the smallest sphere containing all masses of the planetary body). Nevertheless, these expansions are commonly employed inside this bounding surface without any corrections. Justification of this procedure has been debated for several decades, but conclusions among scholars are indefinite and even contradictory. In this contribution, we examine the use of external spherical harmonic expansions for the gravitational field modelling inside the minimum Brillouin sphere. We employ the most recent lunar topographic LOLA (Lunar Orbiter Laser Altimeter) products and the measurements of the lunar gravitational field by the GRAIL (Gravity Recovery and Interior Laboratory) satellite mission. We analyse selected 39 quantities calculated from the most recent GRAIL-derived gravitational field models and forwardmodelled (topography-inferred) quantities synthesised by internal/external spherical harmonic expansions. The comparison is performed in the spectral domain (in terms of degree variances depending on the spherical harmonic degree) and in the spatial domain (in terms of spatial maps). To our knowledge, GRAIL is the first gravitational sensor ever, which helped to resolve the long-lasting convergence/divergence problem for the analytical downward continuation of the external spherical harmonic expansions, see [1].
Validation of Satellite Gravitational Gradients Grids by Spectral Combination Method and GNSS/Levelling Data Over Norway, Czechia and Slovakia
Pitoňák, Martin ; Šprlák, Michal ; Ophaugh, Vegard ; Omang, Ove C. D. ; Novák, Pavel
The launch of gravity-dedicated satellite missions at the beginning of the new millennium led to an accuracy improvement of global Earth gravity field models (GGMs). One of these missions was the Gravity field and steady-state Ocean Circulation Explorer (GOCE) launched in 2009. As the first ESA's Earth Explorer Mission, the satellite carried a novel instrument, a 3-D gradiometer, which allowed to measure of second-order directional derivatives of the gravitational potential (gravitational gradients) 37 with uniform quality and near-global coverage. The main mission goal was to determine the static Earth's gravity field with the ambitious precision of 1-2 cm in terms of geoid heights and 1 mGal in terms of gravity anomalies for a spatial resolution of 100 km (half wavelength at the equator). More than three years of outstanding measurements resulted in three levels of data products (Level 0, Level 1b and Level 2), six releases of GGMs, and several global grids of gravitational gradients. The grids, which represent a step between gravitational gradients measured directly along the GOCE orbit and those represented by GGMs, were used mainly in geophysical applications. In this contribution, we validate the official Level 2 product GRD SPW 2 using height anomalies over two test areas in central and northern Europe (Czechia/Slovakia and Norway). A mathematical model based on the least-squares spectral weighting is employed with corresponding spectral weights estimated to validate gravitational gradient grids. This model continues gravitational gradients from the mean orbital altitude of GOCE down to the irregular Earth's surface (not to a sphere) and transforms them to height anomalies in one computational step. Analytical downward continuation errors of the model are estimated using a closed-loop test. Before comparing, height anomalies estimated from gravitational gradients with their reference values derived from GNSS/levelling over the two test areas, the gravitational gradients and reference data are corrected for all systematic effects, such as the tide system conversion. Moreover, the high-frequency part of the gravitational signal is estimated and subtracted from reference data as it is attenuated in the gravitational gradients measured by GOCE. A relative improvement between the release 6 and release 2 gradient grids reaches 48% in terms of height anomalies in Czechia/Slovakia. The relative improvement in Norway is even more significant and reaches 55%. Release 6 of the official Level 2 product GRD SPW 2 gained absolute accuracy with the standard deviation of 9.1 cm over Czechia/Slovakia and 9.6 cm over Norway.
Far Zone Effects for Integral Transformations: Theory and Implementation
Trnka, Petr ; Belinger, Jiří ; Šprlák, Michal ; Pitoňák, Martin ; Novák, Pavel
Integral transformations are a useful mathematical apparatus for modelling the gravitational field and require the formulation of integral estimates including error propagation. For classical integral transformations, this issue has already been studied, but the formulation for all available gravitational observables has not been studied yet. The assumption of integral transformations is global data coverage. In practice, however, data availability is limited, so we divide the global integration into the effects of the near and far zones. The computation of distant zones is a non-negligible systematic effect requiring an accurate calculation. The theory is implemented in the form of a precise software. In this paper, we present the basic theory for the evaluation of the far zones. We also investigate properties of integral kernels and truncation error coefficients. In the numerical experiments, we compare calculation of the far zones by numerical integration with truncated spherical harmonic series. One of the outputs of this contribution is a software library for computation of the far zones for integral transformations mutually relating all quantities up to the third derivatives of the gravitational potential.
The private Business in Czechoslovakia in the second half of the eighties
Novák, Pavel ; Štemberk, Jan (advisor) ; Šalanda, Bohuslav (referee)
The diploma thesis "Private business in Czechoslovakia in the second half of the eighties" focuses on the period of "perestrojka" in the conditions of socialist Czechoslovakia in the second half of the eighties. The aim of the thesis is to describe and especially evaluate the beginnings of private business in socialist Czechoslovakia at the end of the eighties. The research question then is whether this economic form of production and trade had any hope of greater development given the given political order. Derived questions are to what extent private business was successful, what and how big a response it evoked among the population and especially how it was accepted and evaluated by the ruling elite. The thesis traces the change in the attitude of the Communist Party of Czechoslovakia towards private business after Mikhail Gorbachev took over as General Secretary of the Central Committee of the Communist Party of the Soviet Union and the reconstruction of the economic mechanism announced by him both in the Soviet Union and in its satellites. The primary method will be work with archival materials from the National Archives of the Czech Republic, the Archive of the Security Forces and other state organizations, as well as work with information from the contemporary press. The secondary source...
Detection of Malicious Network Traffic Behavior Using JA3 Fingerprints
Novák, Pavel ; Oujezský, Václav
This paper presents a novel approach for classifying spoof network traffic based on JA3 fingerprint clustering. In particular, it concerns the detection of so-called zero-day malware. The proposed method does not work with known JA3 hashes. However, it compares the JA3 fingerprint of captured traffic with JA3 fingerprints of traffic with predefined criteria, such as the use of current cipher suites or protocol, for classification.
University Students' Experience with Postcoital Contraception
Novák, Pavel ; Hanušová, Jaroslava (advisor) ; Váchová, Alena (referee)
The subject of this Bachelor's thesis is the topic of postcoital contraception with a focus on experience of female students of a university with usage of postcoital contraception. The theoretical part contains a description of female anatomy, describes the properties of the female hormonal system and individual physiological processes in the female body. Furthermore, a summary of possible contraceptive methods is created, which results in the key chapter of this work, ie. a decription of individual postcoital contraceptive methods with a focus on hormonal substances which are available in the Czech Republic. The practical part of bachelor's thesis consists of two questionnaire surveys. The first section of the practical part consists of a questionnaire focused on female students of the Faculty of Education, Charles University. It aims to obtain information of these women with different methods of planned parenthood. Furthermore, the emphasis is on postcoital contraception and the experience of the respondees with this emergency method. The data obtained show that 40 % of these women have experience with postcoital contraception and in the vast majority have experienced at least one side effect. The second section of the practical part is focused on pharmacies in the Czech Republic. This...
Forward and Inverse Modeling of Planetary Gravity and Topography
Pauer, Martin ; Čadek, Ondřej (advisor) ; Martinec, Zdeněk (referee) ; Novák, Pavel (referee)
Title: Forward and Inverse Modeling of Planetary Gravity and Topography Author: Martin Pauer Department/Institute: Department of Geophysics MFF UK Supervisor of the doctoral thesis: Doc. RNDr. Ondřej Čadek, CSc., Department of Geophysics MFF UK Abstract: The aim of this work was to investigate various mechanisms compensating the observed planetary topography - crustal isostasy, elastic support and dynamic support caused by mantle flow. The investigated models were applied to three different planetary problems. Firstly we applied dynamic compensation model to explain today large-scale gravity and topography fields of Venus and investigate its mantle viscosity structure. The results seem to support not only models with constant viscosity structure but also a model with a stiff lithosphere and a gradual increase of viscosity toward a core. In the second paper several crust compensation models were employed to estimate the density of the Martian southern highlands crust. Since the used methods depends differently on crustal density changes, we were able to provide some constraints on the maximum density of the studied region. In the third application, the strength of a possible ocean floor gravity signal of Jupiter's moon Europa was studied. It turned out that if the long wavelength topography reaches height at...
The Beuron School and Liturgy
Novák, Pavel ; Kotas, Jan (advisor) ; Opatrný, Aleš (referee)
Subject of my work is the Beuronese art and its relation to the liturgy. The first part concerns generally the beuronese confederation, its foundation, historical development and expansion. The piece draws the creation and the basic solutions of the confederation, coming of the Beuron Art School as an individual style, and presents the most important beuronese performers. The study also surveys the main works of the Beuron Art School and evaluates the School's influence on the main art streams of the period. The work then tries to describe and clarify the relationship between the beuronese conception of sacral art and liturgy using examples of the two most important Prague beuronese monasteries. For this purpose it analyses so called beuronese "Gesamtkunstwerk", using knowledge of the Christian iconography.
Study of Cobaltites and Manganites by NMR and EXAFS
Procházka, Vít ; Štěpánková, Helena (advisor) ; Novák, Pavel (referee) ; Figiel, Henryk (referee)
This Thesis is devoted to a study of physical properties of manganites and cobaltites with perovskite structure. Combination of macroscopic (magnetization measurements and X-ray powder diraction) and microscopic (NMR and EXAFS) methods was applied in order to get a complex and detailed view on the charge and magnetic ordering of transition metals ions in the LaMn1xCoxO3 solid solutions. The Thesis presents new results which were published in international journals. The main result is the determination of details of Mn and Co local environments and the spin arrangement of their individual oxidation states in the ferrimagnetic structure of the compounds studied.

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See also: similar author names
76 NOVÁK, Pavel
101 NOVÁK, Petr
12 Novák, P.
3 Novák, Patrik
76 Novák, Pavel
101 Novák, Petr
3 Novák, Přemek
2 Novák, Přemysl
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