– Construction of large power plants for use of renewable energy sources in Czech Republic

Cílem této bakalářské práce je zpracování rešerše o možnostech výstavby velkých obnovitelných zdrojů energie v ČR. Zejména fotovoltaických elektráren, větrných elektráren, vodních elektráren a elektráren a tepláren na biomasu a zhodnocení vlivu obnovitelných zdrojů energie na stabilitu přenosové soustavy. Je zde dále pojednáváno o problematice spojené s dlouhodobou energetickou koncepcí České republiky a Evropské unie. Hlavní část práce se však zaměřuje na aktuální problematiku využití obnovitelných zdrojů a jejich potenciálního využití v podmínkách České republiky. Dále je práce zaměřena na vliv obnovitelných zdrojů na stabilitu přenosové soustavy a možnosti pro zvýšení její stabilizace.The main goal of this thesis is researching possibilities of implementation of large renewable power sources in the Czech Republic. In concentrates especially on photovoltaic power plants, wind power plants, water power plants, and heating plants and power plants using biomass and assessment of the impact of renewable power sources on the stability of transmission systems. Among others it deals with long-term conception of power industry in the Czech Republic and the European Union. Nevertheless, the main part of the thesis focuses on an actual issue of exploatation of renewable sources under specific conditions of the Czech Republic. The problematic of the influence of renewable power sources on the stability of transmission grids and possibilities of strengthening that stability is reflected too.

Proposal for the new concept of assembling water ventilation systems of thermoregulation of a motor at an assembly line

Cílem této diplomové práce je zpracování návrhu konceptu montážní linky pro montáž vodních ventilů systému termoregulace motoru. Návrh se skládá z určení taktu linky, počtu potřebných pracovníků a vytvoření tří možných variant řešení montážní linky, z nichž bude na základě více kriteriálního hodnocení vybrána finální varianta.The aim of this diploma thesis is processing of the design of the assembly line for assembling of water ventilation systems of thermoregulation of an engine. The proposal is comprised of determination of the line cycle time, required number of workers and a creation of three possible options of assembly line solution. The final variant will be chosen by using a multi-criterion evaluation.

A novel method for detection and classification of covered conductor faults

Medium-Voltage (MV) overhead lines with Covered Conductors (CCs) are increasingly being used around the world primarily in forested or dissected terrain areas or in urban areas where it is not possible to utilize MV cable lines. The CC is specific in high operational reliability provided by the conductor core insulation compared to Aluminium-Conductor Steel-Reinforced (ACSR) overhead lines. The only disadvantage of the CC is rather the problematic detection of faults compared to the ACSR. In this work, we consider the following faults: the contact of a tree branch with a CC and the fall of a conductor on the ground. The standard protection relays are unable to detect the faults and so the faults pose a risk for individuals in the vicinity of the conductor as well as it compromises the overall safety and reliability of the MV distribution system. In this article, we continue with our previous work aimed at the method enabling detection of the faults and we introduce a method enabling a classification of the fault type. Such a classification is especially important for an operator of an MV distribution system to plan the optimal maintenance or repair the faulty conductors since the fall of a tree branch can be solved later whereas the breakdown of a conductor means an immediate action of the operator

Lab-scale Technology for Biogas Production from Lignocellulose Wastes

Currently-operating biogas plants are based on the treatment of lignocellulose biomass, which is included in materials such as agriculture and forestry wastes, municipal solid wastes, waste paper, wood and herbaceous energy crops. Lab-scale biogas technology was specially developed for evaluating the anaerobic biodegrability and the specific methane yields of solid organic substrates. This technology falls into two main categories – pretreatment equipments, and fermentation equipments. Pretreatment units use physical principles based on mechanical comminution (ball mills, macerator) orhydrothermal treatment (liquid hot water pretreatment technology). The biochemical methane potential test is used to evaluate the specific methane yields of treated or non-treated organic substrates. This test can be performed both by lab testing units and by lab fermenter

Effect of membrane separation process conditions on the recovery of syngas components

The presented study focuses on inspecting the dependency between process conditions, especially permeate and retentate pressure and component recovery of H2, CO, and CO2 during a membrane separation of model syngas. Experiments with both pure components and a model mixture were performed using a laboratory membrane unit Ralex GSU-LAB-200 with a polyimide hollow fibre module with 3000 hollow fibres. Permeability values were established at 1380 Barrer for H2, 23 Barrer for CO, and 343 Barrer for CO2. The measured selectivities differ from the ideal ones: the ideal H2/CO2 selectivity is 3.21, while the experimental values range from over 4 to as low as 1.2 (this implies that an interaction between the components occurs). Then, the model syngas, comprised of 16% H2, 34% CO, and 50% CO2, was tested. The recovery of each component decreases with an increasing permeate pressure. At a pressure difference of 2 bar, the recovery rate for H2, for a permeate pressure of 1.2 bar, is around 68%, for 2.5 bar, the values drop to 51%, and for 4 bar, the values reach 40% only. A similar trend was observed for CO2, with recovery values of 59%, 47% and 37% for permeate pressures of 1.2 bar, 2.5 bar and 4 bar, respectively

The effect of rotor geometry on particle size characteristics for knife-milled wheat straw

The paper aimed to experimentally identify the effect of rotor blade geometry on particle size characteristics for the knife-milled wheat straw of 12.5 wt % moisture content. Biomass was systematically reduced in size using two-blade rotor geometries (linear and screw), varying the following conditions: rotor speeds of 10.2 - 20.4 m s - 1 and screen sieve sizes of 0.75 - 10 mm. It was identified that rotor blade geometry affected particle size. The higher the rotational rotor speed and the screen sieve size, the higher the difference in particle size characteristics. The original empiric model was derived and calibrated by studying the mutual relationships among process variables. The model allows predicting characteristic particle size D50 for individual rotor blade geometries, knowing rotor speed and screen sieve size. The accuracies of R2=0.94 for linear- and R2=0.92 for screw-blade rotor geometry were reached for particle size estimation using the derived model.This research was supported by the Ministry of Education, Youth and Sports of the Czech Republic under OP RDE grant number CZ.02.1.01/0.0/0.0/16_019/0000753 "Research centre for low-carbon energy technologies

Cost-based holistic twig joins

An evaluation of XML queries such as XQuery or XPath expressions represents a challenging task due to its complexity. Many algorithms have been introduced to cope with this problem. Some of them, called binary joins, evaluate separated parts of a query and subsequently merge intermediate results, while the others, called holistic twig joins, evaluate a query as a whole. Moreover, these algorithms also differ in what index data structure they use to handle XML data. There exist cost-based approaches utilizing binary joins and various index data structures; however, they share a limitation. The limitation is that they cannot perform a join between query nodes not having a direct XPath relationship. Such a join can be advantageous especially if their joint selectivity is high. Since holistic joins work with all query nodes they overcome this limitation. In this article, we introduce such a holistic twig join called CostTwigJoin. To the best of our knowledge, CostTwigJoin is the first holistic join capable of combining various index data structures during an evaluation of an XML query. Usage of the holistic join has yet another advantage for cost-based approaches: an optimizer does not have to resolve the order of binary joins; therefore, the search space is reduced. In this article, we perform thorough experiments on hundreds of queries to evaluate our approach and demonstrate its advantages.Web of Science52332