Real-time Simulation of 3 Parallel PWM Rectifiers

This paper describes the development of areal-time model up to 3 parallel PWM rectifiers and itsimplementation on FPGA using LabVIEW developmentenvironment. The main benefit of this real-time model is thefact that there is no need for a real device or a test stand fordebugging of traction drive control SW. The Hardware-inthe-Loop testing with similar RT model of an inductionmachine has already brought large financial and timesavings. Moreover, destructive states or states difficult toevoke can be tested using such a real-time model

Preparation of binary intermetallic material by melting of powder mixture by electron beam

Tato bakalářská práce se zabývá systémem Fe-Al. Práce je rozdělena do dvou částí. Teoretická část obsahuje stručnou charakteristiku intermetalických materiálů, ze kterých se podrobněji věnuje aluminidům železa. Dále práce obsahuje stručný popis procesů práškové metalurgie. V experimentální části byly z prášků hliníku a železa vyrobeny vzorky o různém složení, které byly přetaveny elektronovým paprskem. Na vzorcích byl proveden metalografický rozbor.The bachelor thesis deals with system Fe-Al. Thesis is divided into two parts. Literature analysis contains a brief characterization of intermetallic materials, especially is focused on iron aluminides. Thesis also contains a brief description of processes of powder metallurgy. In experimental part metal powders of aluminium and iron were used to create samples with different composition, which were melted by electron beam. Samples was studied by metallographic analysis.

The evaluation of the education programme Centre of the Environmental Education Divizna - Sick Planet

katedra: KPP; přílohy: CD; rozsah: 40This Bachelor thesis deals with the evaluation of the education programme Sick Planet which is designed for children on eighth and ninth grade of elementary school as well as for children in first and second year at high school. The aim was to evaluate program effectiveness. The program focuses on acquiring knowledge about current global issues.Information for research were obtained through questionnaires and interviews with participants. Data were obtained from participants aged from 14 to 15 years. It can be said that the efficiency of the Sick Planet is not optimal. The program affects the partial knowledge of global issues but at the same time it has no significant influence on the attitudes of pupils.Based on the research are discussed possible measures to modify the program.Bakalářská práce se zabývá evaluací výukového programu Nemocná planeta, jenž je určen pro žáky osmých až devátých tříd základní školy a prvního a druhého ročníku střední školy. Jejím cílem bylo zhodnotit efektivitu programu. Program se zaměřuje na získávání znalostí o současných globálních problémech.Informace pro výzkum byly získány pomocí dotazníků a rozhovorů s účastníky, data jsou od účastníků ve věku 14 až 15 let.Lze konstatovat, že efektivita programu Nemocná planeta není optimální. Program ovlivňuje dílčí znalosti o globálních problémech, nemá však podstatný vliv na postoje žáků.Na základě provedeného výzkumu je možno diskutovat o možných opatřeních vedoucích k modifikacím programu

determination of kinetic parameter of reactions using DSC

Tato diplomová práce se zabývá DSC měřením a výpočtem kinetických parametrů. V teoretické části je nejprve stručně popsána alotropie železa a poté popis samotné DSC analýzy. Práce také obsahuje rozdělení a odvození isokonverzních metod pro výpočet aktivační energie. V experimentální části je provedena série měření čistého železa připraveného metodou Cold Spray. V práci je zkoumán vliv deformace na Curieho teplotu magnetické přeměny v -Fe a transformace > v Fe. Pro transformaci > je vypočtena aktivační energie pro různé stupně deformace. Stupeň deformace je sledován kanálovacím kontrastem.The master thesis deals with DSC measurments a calculation of kinetic parameters. In the theoretical part, iron alotropy is briefly described, followed by a description of the DSC analysis itself. The thesis also includes division and derivation of isoconversional methods for calculating the activation energy. In the experimental part, a series of measurments is perfomed on pure iron prepared by Cold Spray method. In the paper the influence of deformation on the Curie temperature of the magnetic transformation in -Fe and transformation > is investigated. The activation energy is calculated for transformation > for different degrees of deformation. The degree of deformation is monitored by channeling contrast.

Control circuits of railway lift

Diplomová práce se zabývá mechanickým a elektrickým návrhem pohonu šikmého kolejového stavebního výtahu. Je provedena teoretická rešerše ohledně bezdrátových modulů a řídících jednotek. V návrhu jsou vybrány jednotlivé komponenty a je navrženo celkové zapojení systému vysílače, přijímače a výtahu. Dále je naprogramována logika výtahu v programu Arduino IDE, která umožňuje dálkové ovládání motoru pomocí frekvenčního měniče.This master thesis deals with the mechanical and electrical design of the drive of the inclined construction lift. Individual components are selected in the design. Furthermore, a theoretical research is carried out regarding wireless modules and logic controllers. The selection of sensors is made and the method of retrieving signals from sensors and converting them into iputs the control circuits is also outlined. A program is written in Arduino IDE that wirelessly controls the motion of a motor via variable frequency drive.

Experimental investigations of wooden beam ends in masonry with internal insulation: results contrasting three years of the experiment

This paper deals with hygro-thermal performance of wooden beam ends embedded in masonry walls with lime-cement plaster applied on the external side. Three different insulation systems are attached on the internal side of masonry. The real scale experiment has been monitored for three consecutive years. Microclimatic conditions in joist pockets were assessed by VTT mold growth index. The paper shows the influence of two changes of boundary conditions on the microclimate in joist pockets. First, moisture load on the internal side of building enclosure was increased (24 °C, 60 % in winter 2016/2017 instead 20 °C, 50 % in winter 2015/2016). Then, the artificial short-time rain event brought liquid water onto the external surface of building enclosure in July 2017. The rain intensity was chosen so as to mimic the intensive summer thunderstorm. The increase of water vapor concentration in the air on the internal side led to suitable conditions for mold growth in unsealed joist pockets of a vapor open insulation system. On contrary, microclimate in sealed joist pockets in both vapor open and vapor closed insulation systems stayed in acceptable levels with no mold growth. The artificial rain event significantly changed the hygro-thermal performance of joist pockets. Drying season was shortened and the relative humidity in joist pockets overtook the time profile of external relative humidity

Life Cycle Assessment Method – Tool for Evaluation of Greenhouse Gases Emissions from Agriculture and Food Processing

The chapter focuses on the use of the Life Cycle Assessment method to monitor the emission load of foods from different systems of farming production. The products of the conventional and organic farming production intended for public catering are compared within the SUKI and UMBESA international projects. Conventional farming is mainly characterized by high inputs of mineral fertilizers, chemical pesticides, the use of hormones and stimulants in animal husbandry. It is a system based on the highest possible yields without respecting the natural principles of nature. Conversely, organic farming is a system of production established by the legislation that respects fundamental natural cycles, such as crop rotation, ensures welfare of animals, prohibits the use of fertilizers, pesticides, and other substances of synthetic origin. However, lower yields are a big disadvantage. In the Czech Republic, only about one tenth of the agricultural fund is currently used for organic farming. Arable land constitutes only about 10% of the total area of agricultural land, other areas are mainly grasslands and orchards. The work primarily aims to answer to the question whether the selection of foods may contribute to decrease in greenhouse gas emissions, which is a part of the objectives of many policies. Besides the comparison of agricultural production, processed and unprocessed foods, local and imported foods and fresh and stored foods were compared as well. The Life Cycle Assessment (LCA), which is used to assess environmental impacts of products and services throughout their entire life cycle, was used to quantify the emission load. This method may be briefly characterized as a gathering of all inputs and outputs that take place during the production in the interaction with the environment. These inputs and outputs then also determine the impact on the environment. The LCA consists of four successive and iterative phases: This concerns the definition of objectives and scope, inventory analysis, impact assessment and interpretation of the results. The LCA was originally developed for the assessment of impacts of especially industrial products. Certain methodological problems and deficiency, which bring a level of uncertainty of the results, have been caused by its adaptation to agricultural product assessment, but this method is still recommended for comprehensive assessment of environmental impacts of agricultural production and the comparison of different agricultural products. In this study, a Cradle-to-Gate assessment was performed, which means that the impacts of products (in this case the emission formation) were evaluated only to the delivery of foods to public facilities, further treatment and waste management was not assessed. About 20 most frequently used foods for school catering facilities were compared. The results of the project confirm the general assumption about the less emission load of unprocessed, fresh and local products. It may not clearly state that products from organic farming produce less emissions when comparing agricultural systems. It always depends on the particular crop. The absence of synthetic substances such as fertilizers and pesticides reduces the emission load of organic farming, on the other hand, a higher number of mechanical operations and especially the lower income clearly increase the emission burden, therefore, in several cases, lower emission loads of crops were achieved using the conventional farming system. However, less emission may be achieved within the organic farming system. Among 11 evaluated agricultural products, 8 organic products and only 3 conventional ones go better. The situation is different regarding the following phases of food production, processing and transport. The transport phase significantly worsens the environmental profile of organic foods, because transport distances are too far due to insufficient processing capacity and underdeveloped market networks, and often exceed the emission savings from the agricultural phase. On the contrary, conventional foods are carried within relatively short distances, therefore the final emission load of conventional foods is in many cases fewer than the load of organic foods. This fact is also confirmed by the result of the study, because among 22 evaluated foods, organic food goes better in 11 cases and conventional food in 11 cases as well

Characterization of the Graphite Pile as a Source of Thermal Neutrons

The absorption cross sections of low energy neutrons obey 1/v law for most materials. Therefore, the detection efficiency of a particular detector increase with decreasing neutron energy. Consequently, most of neutron measuring instruments consist of the detector of thermal neutrons which is located inside of the polyethylene moderator. Development of such instruments requires testing and response calibrations in the field of thermal neutrons. Availability of thermal neutron beams on nuclear reactors is limited and access to them is rather complicated, so it is more convenient to moderate neutrons from the radionuclide neutron sources. Since radionuclide neutron sources are producing fast neutrons it is necessary to use an appropriate moderator material like heavy water or graphite to thermalize neutrons from the source and to avoid thermal neutron capture in the same time.The absorption cross sections of low energy neutrons obey 1/v law for most materials. Therefore, the detection efficiency of a particular detector increase with decreasing neutron energy. Consequently, most of neutron measuring instruments consist of the detector of thermal neutrons which is located inside of the polyethylene moderator. Development of such instruments requires testing and response calibrations in the field of thermal neutrons. Availability of thermal neutron beams on nuclear reactors is limited and access to them is rather complicated, so it is more convenient to moderate neutrons from the radionuclide neutron sources. Since radionuclide neutron sources are producing fast neutrons it is necessary to use an appropriate moderator material like heavy water or graphite to thermalize neutrons from the source and to avoid thermal neutron capture in the same time

Detection of mixed fields of neutron and photon radiation using 3He and new scintillation materials

The poster includes experimental measurements with 3He and the latest scintillation materials EJ-299-33 in fields of neutron and photon radiation using modern electronics which we designed. Electronic part of the measuring system is built on recently developed AD converter with very high sampling frequency (1 GHz). In the theoretical part, the Monte Carlo simulations of response characteristics of the measured scintillation materials are presented.Poster obsahuje experimentální měření za požití He-3 a nejnovějšího scintilačního materiálu EJ-299-33 v polích neutronů a fotonů. Elektronická část je postavena na základě velmi rychlých AD převodnků (1 GHz). V teoretické části je popsána Monte Carlo simulace odezvové matice použitých detektorů.The poster includes experimental measurements with 3He and the latest scintillation materials EJ-299-33 in fields of neutron and photon radiation using modern electronics which we designed. Electronic part of the measuring system is built on recently developed AD converter with very high sampling frequency (1 GHz). In the theoretical part, the Monte Carlo simulations of response characteristics of the measured scintillation materials are presented