TAKING A SNAPSHOT : Discovering Escalation Prone Countries Through Structural Conditions and QCA

This paper introduces a method of conflict escalation prediction based on long-term structural conditions, drawn from open sources, and QCA (Qualitative Comparative analysis). The combination of the two components offers a model of prediction, which is comparable to other more sophisticated and resourced systems. Moreover, it offers a more sensitive estimation of an escalation.Tento článek představuje metodu předvídání eskalace konfliktů na základě dlouhodobých, strukturálních podmínek z otevřených zdrojů za použití kvalitativní komparativní analýzy (QCA). Kombinací těchto dvou prvků vzniká model a metoda predikce, která je v efektu predikce srovnatelná s dalšími, daleko sofistikovanějšími a lépe financovanými systémy a nabízí citlivější odhad eskalace

Cylinder Deactivation for Internal-combustion Engines

Práce je zaměřená na technologii úspory paliva a snížení emisí spalovacích motorů nazývanou vypínání válců. V první části je uveden historický vývoj této technologie spolu s objasněním podstaty snížení spotřeby paliva. Následuje popis důsledků vypínání válců a uvedení jednotlivých koncepcí používaných u zážehových motorů doplněný o výsledky testů provedených na vznětových motorech, kde se tato technologie doposud nepoužívá. V poslední části práce jsou uvedeny další komponenty motorů s vypínáním válců, zejména pak prostředky k tlumení vibrací, a příklady konkrétních aplikací.This bachelor’s thesis focuses on a technology reducing fuel consumption and emissions called cylinder deactivation. The evolution of the technology is described in the first part of the thesis together with explanation of the nature of fuel savings. The description of consequences associated with usage of the technology and possible design approaches for gasoline engines are written in the following part. The thesis also incorporates the results of test performed on diesel engines, where the technology is not currently in production. The last part includes other components used in engines with cylinder deactivation, especially vibration absorbers, together with some examples of application of this technology.

Cylinder deactivation of a spark-ignition engine

Práce se zabývá technologií vypínání válců, která umožňuje snížení spotřeby paliva a emisí. V první části jsou shrnuty možnosti aplikace vypínání válců a možné výhody plynoucí z kombinace s jinými technologiemi. Dále práce obsahuje konstrukční návrhy ventilových rozvodů dvou systémů vypínání válců pro řadový čtyřválcový motor a výsledky dynamických simulací jeho klikového mechanismu.This thesis focuses on a technology called cylinder deactivation. The technology helps reducing emissions and fuel consumption. The first part summarizes the possibilities of application of the cylinder deactivation technology as well as advantages resulting from combination with other technologies. The thesis also consists of two design options for valvetrain in inline four-cylinder engine and the results of simulations of dynamics of its cranktrain.

Must the best laboratory prepared catalyst also be the best in an operational application?

Three cobalt mixed oxide deN(2)O catalysts, with optimal content of alkali metals (K, Cs), were prepared on a large scale, shaped into tablets, and tested in a pilot plant reactor connected to the bypassed tail gas from the nitric production plant, downstream from the selective catalytic reduction of NOx by ammonia (SCR NOx/NH3) catalyst. High efficiency in N2O removal (N2O conversion of 75-90% at 450 degrees C, VHSV = 11,000 m(3) m(bed)(-3) h(-1)) was achieved. However, a different activity order of the commercially prepared catalyst tablets compared to the laboratory prepared catalyst grains was observed. Catalytic experiments in the kinetic regime using laboratory and commercial prepared catalysts and characterization methods (XRD, TPR-H-2, physisorption, and chemical analysis) were utilized to explain this phenomenon. Experimentally determined internal effectiveness factors and their general dependency on kinetic constants were evaluated to discuss the relationship between the catalyst activity in the kinetic regime and the internal diffusion limitation in catalyst tablets as well as their morphology. The theoretical N2O conversion as a function of the intrinsic kinetic constants and diffusion rate, expressed as effective diffusion coefficients, was evaluated to estimate the final catalyst performance on a large scale and to answer the question of the above article title.Web of Science92art. no. 16

Co-Mn-Al mixed oxides promoted by K for direct NO decomposition: Effect of preparation parameters

Fundamental research on direct NO decomposition is still needed for the design of a sufficiently active, stable and selective catalyst. Co-based mixed oxides promoted by alkali metals are promising catalysts for direct NO decomposition, but which parameters play the key role in NO decomposition over mixed oxide catalysts? How do applied preparation conditions affect the obtained catalyst's properties? Co4MnAlOx mixed oxides promoted by potassium calcined at various conditions were tested for direct NO decomposition with the aim to determine their activity, stability and selectivity. The catalysts were prepared by co-precipitation of the corresponding nitrates and subsequently promoted by KNO3. The catalysts were characterized by atomic absorption spectrometry (AAS)/inductive coupled plasma (ICP), X-ray photoelectron spectrometry (XPS), XRD, N-2 physisorption, temperature programmed desorption of CO2 (TPD-CO2), temperature programmed reduction by hydrogen (TPR-H-2), species-resolved thermal alkali desorption (SR-TAD), work function measurement and STEM. The preparation procedure affects physico-chemical properties of the catalysts, especially those that are associated with the potassium promoter presence. The addition of K is essential for catalytic activity, as it substantially affects the catalyst reducibility and basicity-key properties of a deNO catalyst. However, SR-TAD revealed that potassium migration, redistribution and volatilization are strongly dependent on the catalyst calcination temperature-higher calcination temperature leads to potassium stabilization. It also caused the formation of new phases and thus affected the main properties-S-BET, crystallinity and residual potassium amount.Web of Science97art. no. 59

K-modified Co-Mn-Al mixed oxide-effect of calcination temperature on N2O conversion in the presence of H2O and NOx

The effect of calcination temperature (500-700 degrees C) on physico-chemical properties and catalytic activity of 2 wt. % K/Co-Mn-Al mixed oxide for N2O decomposition was investigated. Catalysts were characterized by inductively coupled plasma spectroscopy (ICP), X-ray powder diffraction (XRD), temperature-programmed reduction by hydrogen (TPR-H-2), temperature-programmed desorption of CO2 (TPD-CO2), temperature-programmed desorption of NO (TPD-NO), X-ray photoelectron spectrometry (XPS) and N-2 physisorption. It was found that the increase in calcination temperature caused gradual crystallization of Co-Mn-Al mixed oxide, which manifested itself in the decrease in Co2+/Co3+ and Mn3+/Mn4+ surface molar ratio, the increase in mean crystallite size leading to lowering of specific surface area and poorer reducibility. Higher surface K content normalized per unit surface led to the increase in surface basicity and adsorbed NO per unit surface. The effect of calcination temperature on catalytic activity was significant mainly in the presence of NOx, as the optimal calcination temperature of 500 degrees C is necessary to ensure sufficient low surface basicity, leading to the highest catalytic activity. Observed NO inhibition was caused by the formation of surface mononitrosyl species bonded to tetrahedral metal sites or nitrite species, which are stable at reaction temperatures up to 450 degrees C and block active sites for N2O decomposition.Web of Science1010art. no. 113

Catalytic oxidation of ammonia over cerium-modified copper aluminium zinc mixed oxides

Copper-containing mixed metal oxides are one of the most promising catalysts of selective catalytic oxidation of ammonia. These materials are characterized by high catalytic efficiency; however, process selectivity to dinitrogen is still an open challenge. The set of Cu-Zn-Al-O and Ce/Cu-Zn-Al-O mixed metal oxides were tested as catalysts of selective catalytic oxidation of ammonia. At the low-temperature range, from 250 & DEG;C up to 350 & DEG;C, materials show high catalytic activity and relatively high selectivity to dinitrogen. Samples with the highest Cu loading 12 and 15 mol.% of total cation content were found to be the most active materials. Additional sample modification by wet impregnation of cerium (8 wt.%) improves catalytic efficiency, especially N-2 selectivity. The comparison of catalytic tests with results of physicochemical characterization allows connecting the catalysts efficiency with the form and distribution of CuO on the samples' surface. The bulk-like well-developed phases were associated with sample activity, while the dispersed CuO phases with dinitrogen selectivity. Material characterization included phase composition analysis (X-ray powder diffraction, UV-Vis diffuse reflectance spectroscopy), determination of textural properties (low-temperature N-2 sorption, scanning electron microscopy) and sample reducibility analysis (H-2 temperature-programmed reduction).Web of Science1421art. no. 658

Cylinder deactivation of a spark-ignition engine

This thesis focuses on a technology called cylinder deactivation. The technology helps reducing emissions and fuel consumption. The first part summarizes the possibilities of application of the cylinder deactivation technology as well as advantages resulting from combination with other technologies. The thesis also consists of two design options for valvetrain in inline four-cylinder engine and the results of simulations of dynamics of its cranktrain

Reaction mechanism of NO direct decomposition over K-promoted Co-Mn-Al mixed oxides – DRIFTS, TPD and transient state studies

The reaction mechanism of direct NO decomposition over Co4MnAlOx mixed oxides prepared by co-precipitation method and promoted by 0-3.1 wt.% of potassium was studied. Temperature programmed desorption of NO and in-situ diffuse reflectance infrared Fourier transform spectroscopy confirmed the presence of several nitrogen species (adsorbed NO, NO-,NO2-, and NO3-) present on the catalyst surface and revealed that O2 desorption occurs at the high temperature region together with the NO desorption as the product of NO2and/or NO3- decomposition. This region corresponds with the temperature of launching NO conversion curve, which together with the results from the transient state experiments proved that O2 desorption is the slowest step while the reaction steps including NOx-formation and those leading to N2 release are fast. The Langmuir-Hinshelwood mechanism was proposed as a plausible way of direct NO decomposition over K/ Co4MnAlOx catalysts and NO2- and NO3- were determine as the main reaction intermediates.Web of Science12026625