50 research outputs found
Evaluation of technology for the biomass incineration
Tato bakalářská práce uvádí přehled metod pro zpracování a využití biomasy. Úvodní část je věnována zdrojům biomasy, dále jsou popsány samotné technologie pro netermické a energetické využití biomasy.This bachelor thesis presents an overview of methods used for processing and utilization of biomass. The introductory part is devoted to sources of biomass, the following part describes the technologies for non-thermal and energy biomass use.
Structural integrity analysis of storage tank using FEM
Tato diplomová práce se zabývá problematikou uskladňovacích nádrží na ropné produkty. V úvodní části práce je uvedeno rozdělení nádrží, související normy a údržba nádrží. Další část práce se zabývá analýzou reálného případu havárie nádrže. Byl vytvořen 3D model havarované nádrže dle naměřených hodnot v nádrži. Dále byl vytvořen skořepinový model nádrže podle výkresové dokumentace a analýza výsledků šetření havárie pomocí metody konečných prvků (MKP) v programu ANSYS. Byl proveden výpočet odolnosti konstrukce na boulení dle ČSN EN 1993-1-6 a jeho porovnání s výsledky výpočtu MKP v programu ANSYS. Cílem práce bylo nalezení kritického stavu konstrukce a stanovení kritického vnitřního podtlaku a přetlaku. Na závěr byla určena opatření pro bezpečný provoz a nastavení ventilačních členů.This diploma thesis deals with the storage tanks for petroleum products. The introductory part is devoted to the distribution of the storage tanks, associated standards and maintenance of tanks. Another part goes about the analysis of real case of a tank collapse. There was created a 3D model of the collapsed tank according to the measured values in the tank. It was created a tank shell model by drawing documentation and analysis of the results of the accident investigation using the finite element method (FEM) by program ANSYS. Calculation was performed on the buckling resistance of the structure according to ČSN EN 1993-1-6 and its comparison with the results of FEM analysis in ANSYS. The aim of the study was to find the critical condition of the structure and determination of the critical internal underpressure and overpressure. At the end there were determined measures for safe operation and settings of the valve members.
The Effects of Climate Change on Variability of the Growing Seasons in the Elbe River Lowland, Czech Republic
This research aimed to identify an approach for adaptation of agriculture to increased climate variability and projected changes, taking into account regional specificity of climate change. Changes in the timing of growing season (GS) parameters for both observation and models data were computed using daily mean temperatures for three thresholds that correspond to the physiological requirements of the vegetable types. This research included a new assessment of the potential impacts of climate change on the GS of vegetables grown in the Elbe River lowland, one of the largest farmed vegetable regions in Central Europe. To accomplish this, a comprehensive analysis was conducted of the spatiotemporal variability of the date of the beginning of the growing season (BGS), the date of the end of the growing season (EGS), and the length of the growing season (GSL) for the period 1961–2011. In addition, an assessment was made of the potential changes in the dates of the BGS, EGS, and GSL for the Elbe River lowland, simulated using the regional climate models. Prospective areas for growing thermophilic vegetables in the study region were also determined
Validity and reliability of drought reporters in estimating soil water content and drought impacts in central Europe
Increasing drought is considered one of the major threats associated with climate change in central Europe. To provide an objective, quantitative tool that represents current drought conditions, the Czech Drought Monitor System (CzechDM) was established in 2012. Like other drought monitoring systems worldwide, the CzechDM uses several approaches to provide drought data. However, the CzechDM is unique internationally due to its utilization of a network of voluntary reporters (farmers) who complete a weekly online questionnaire to provide information about soil water content and the impacts of drought on crop yield. In this study, the results from the questionnaires from individual farms were aggregated by district. Reporters’ data were compared and validated with the outputs of the SoilClim model (a core tool of the CzechDM) and with other drought monitoring tools, such as the water balance model, the soil water index and the evaporative stress index. The soil water content estimated by the reporters was significantly correlated (on average r = 0.8) with the outputs of the SoilClim model. Conversely, the correlation between the drought impacts on yield estimated by the reporters and the SoilClim outputs was lower (on average r = 0.4), suggesting that in situ observations by farmers provide additional insights into the occurrence of drought impacts. Importantly, it was found that farmers reported significant drought impacts on yield earlier in the season than any other methods (models or remote sensing). The main findings of this study are that the drought monitoring provided by reporters is a useful and reliable component of the CzechDM. We conclude that weekly reports by farmers represent a significant enhancement to drought monitoring and have potential for use in developing automated approaches that combine in situ, modeling and remote sensing data within a data fusion or machine learning framework
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The 1921 European drought: impacts, reconstruction and drivers
The European drought of 1921 is assessed in terms of its impacts on society and in terms of its physical characteristics. The development of impacts of the drought are categorized by a systematic survey of newspaper reports from five European newspapers covering the area from England to the Czech Republic and other parts of Europe. This is coupled to a reconstruction of daily temperature and precipitation based on meteorological measurements to quantify the drought severity and extent, and reanalysis data are used to identify its drivers. This analysis shows that the first impacts of the drought started to appear in early spring and lingered on until well into autumn and winter, affecting water supply and agriculture and livestock farming. The dominant impact in western Europe is on agriculture and livestock farming while in central Europe the effects of wildfires were reported on most often. The peak in the number of reports is in late summer. Preceding the first impacts was the dry autumn of 1920 and winter 1920–1921. The area hardest hit by the drought in the following spring and summer was the triangle between Brussels, Paris and Lyon, but a vast stretch of the continent, from Ireland to the Ukraine, was affected. The reported impacts on water supply and water-borne transport in that region were matched by an analysis of the hydrological situation over the Seine catchment. On average, the 1921 summer was not particularly hot, but the heatwave which was observed at the end of July saw temperatures matching those of the heatwaves in modern summers. Similar to modern droughts, an anticyclone was present roughly over the British Isles, maintaining sunny and dry weather in Europe and steering away cyclones to the north. Its persistence makes it exceptional in comparison to modern droughts.
The 1921 drought stands out as the most severe and most widespread drought in Europe since the start of the 20th century. The precipitation deficit in all seasons was large, but in none of the seasons in 1920 and 1921 was the precipitation deficit the largest on record. The severity of the 1921 drought relates to the conservative nature of drought which amplifies the lack of precipitation in autumn and winter into the following spring and summer
DYNAMICS OF WINTER SEVERITY AND ITS EFFECT ON RECREATION
Air temperature in winter months and colder half-year is an important factor for wide range of human activities, including recreation. As a result of current climate change, average air temperatures increase in winter as well. This, however, does not mean that there are no frosts. Each winter season can be assessed using several parameters. In this paper we used the sum of effective air temperatures below 0 degrees C and- 5 degrees C. Absolute minimum air temperature was used as an indicator of the extremity of a particular period. Space-time analysis has been performed for both parameters. Air temperatures in winter months are to a large extent influenced by the continentality of the climate. In general, the temperatures in Bohemia rise faster compared to Moravia and the absolute lowest minimum air temperatures are observed in the Western parts of the country. Based on a multiparametric analysis of climate characteristics, the coldest winter and colder half-year was in 1963, in contrast, the mildest winter was in 2007
Quality control and homogeneity testing of daily time series of eca ECA&D
For any meaningful climate analysis, it is necessary for analysed time series to be homogeneous, which means that their variations are caused solely by variations in weather and climate (Conrad and Pollak 1950). Th us, prior to any analysis, the need to homogenize data and check their quality arises. Unfortunately, most of the climatological series that span over decades, to centuries, contain inhomogeneities caused by station relocations, exchange of observers, changes in the vicinity of the stations (e.g. urbanization), changes in instruments, observing practices (e.g. diff erent formulas for calculating daily means, diff erent observation times), etc. In this work we focused on testing the quality and homogeneity of daily data produced by ECA&D. Th is is a free available dataset of daily meteorological elements from the European Climate Assessment & Dataset (http://eca.knmi.nl/). Th is database was used to create a regular grid of EOBS points, which are oft en used to validate climate models
Financial analysis of Holmes Place Czech Republic, s.r.o.
Cílem této práce je provedení finanční analýzy společnosti Holmes Place Czech Republic, s.r.o. a to v rámci posledních pěti účetních obdobích. Práce je rozdělena do dvou hlavních částí, tedy části teoretické a praktické. V teoretické části je popisován význam finanční analýzy, její uživatelé a její interpertace. Důraz je zde kladen na objasnění dílčích pojmů jako jsou vertikální a horizontální analýza a poměrové ukazatele (rentabilita, zadluženost, solventnost, aktivita a likvidita). V praktické části je nejprve nastíněn profil společnosti, její předmět podnikání a historie. Následuje vlastní finanční analýza podle předlohy a postupů popisovaných v části teoretické. Na závěr je finanční stav společnosti zhodnocen a jsou navrženy postupy správného hospodaření do budoucnosti.The aim of this thesis is to execute a financial analysis of the Holmes Place Czech Republic, s.r.o. using information of the last five financial years. The thesis consists of the two main parts. First part is theoretical, the second one is practical. In the theoretical part, substance of the financial analysis is being explained as well as its users and interpretation. It is also focused on the clarification of the terms like vertical and horizontal analysis and ratio indicators (profitability, liquidity, activity, indebtedness, solvency). The practical part starts with the brief background of the firm and it is followed by the financial analysis itself according to the methodology described in the theoretical part. At the end, there is an evaluation of the firm's financial situation and procedures leading to an economical future are suggested
Physiological equivalent temperature as an indicator of the UHI effect with the city of Prague as an example
Description of an Urban Heat Island (UHI) using the difference in air temperature is one of the world's most studied characteristics. If, however, one wants to express how the temperature is perceived by humans, one must consider the overall effect of air temperature, wind speed, air humidity and radiation flows, which is expressed using temperature bioclimatological indexes. One of them is the socalled physiological equivalent temperature (PET), which is used for quantification of the overall effect of meteorological parameters combined with human energetic balance and which is perceived by humans. The RayMan (MATZARAKIS et al. 2007, 2010) microscale models in the city of Prague were used to simulate biometeorological conditions describing the effect on humans using PET
Determination and Changes in Winter Severity in the Period between 1961 and 2015
Values of the minimum air temperatures during cold periods, especially winter, have often negative impacts on a wide range of human activities. In the past there have been many cases when rapid decrease in air temperature caused damages to machines, halted traffic etc. Every winter or cold half-year can be assessed using several parameters. In this article, three climatological characteristics were used. First was the average air temperature. Second was the sum of effective air temperatures below 0°C and -5°C. Last characteristic, which determines the extremity of that particular period, is the absolute minimum air temperature. Space-time analysis was performed for all the three characteristics. Statistically, the most significant change was found in case of the average air temperature – there is a gradual warming since 1961. Air temperatures during winter are to a large extent affected by the continentality of the climate. In Bohemia, the warming is faster than in Moravia and the western part of the country has the lowest absolute minimum air temperatures. Using multiparametric analysis of climatological characteristics it was found that the coldest winter and coldest half-year from the analyzed years was in 1963. In contrast, mildest winter was in 2007. Current climatological models predict that winter temperatures by the end of 21st century will be higher by 2.4°C to 4.9°C, which would mean a significant change in the current winter conditions.\