Auxiliary power sources in electric traction

Účelem této práce je návrh pomocných měničů v systémech elektrické trakce. Konkrétně se zde zabýváme dvěma různými měniči (tyto měniče byly použity pro přímou aplikaci v trakčních vozidlech vyvíjených na UVEE FEKT VUT Brno). První měnič byl použit pro napájení pomocných pohonů elektrické lokomotivy. Druhý měnič byl použit k napájení palubních spotřebičů elektromobilu s palivovým článkem.The purpose of this thesis is proposal of auxiliary power sources in electric traction. Specifically we deal with two converters. Both of them were used in traction vehicle's applications, which are developed by the Department of Power Electrical and Electronic Engineering, Brno University of Technology. First converter was used as a power supply in secondary traction mechanism of electric locomotive. Second one to power supply of dash board in automobile with fuel cells.

Panoramatic View Reconstruction

Tato práce se zabývá krok za krokem procesem sestavování panoramatického obrazu z několika dílčích snímků scény pořízených perspektivní kamerou otáčenou kolem jejího optického středu. Jsou zde popsány algoritmy detekce významných bodů v obraze, možnosti výpočtu matice homografie a metody odstranění nežádoucích ostrých přechodů mezi zdrojovými snímky ve výsledném panoramatickém obraze. Součástí práce je i samostatná aplikace, v níž jsou implementovány některé algoritmy popsané v této práci.This paper deals step by step with process of stitching images taken by perspective camera rotated by its optical center into the panoramic image. There are described keypoint searching algorhytms, possibilities of calculating homography matrix and methods of eliminating unwanted seams between source images in final panoramic image. A part of this paper is also standalone application in which are implemented some algorhytms described in the work.

Oligodendroglial alpha-synucleinopathy and MSA-like cardiovascular autonomic failure: Experimental evidence

AbstractMultiple system atrophy (MSA) is a fatal, rapidly progressive neurodegenerative disease with limited symptomatic treatment options. Discrimination of MSA from other degenerative disorders crucially depends on the presence of early and severe cardiovascular autonomic failure (CAF). We have previously shown that neuropathologic lesions in the central autonomic nuclei similar to the human disease are present in transgenic MSA mice generated by targeted oligodendroglial overexpression of α-syn using the PLP promoter. We here explore whether such lesions result in abnormalities of heart rate variability (HRV) and circadian rhythmicity which are typically impaired in MSA patients.HRV analysis was performed in five month old transgenic PLP-α-syn (tg) MSA mice and age-matched wild type controls. Decreased HRV and alterations in the circadian rhythmicity were detected in the tg MSA group. The number of choline-acetyltransferase-immunoreactive neurons in the nucleus ambiguus was significantly decreased in the tg group, whereas the levels of arginine-vasopressin neurons in the suprachiasmatic and paraventricular nucleus were not affected. Our finding of impaired HRV and circadian rhythmicity in tg MSA mice associated with degeneration of the nucleus ambiguus suggests that a cardinal non-motor feature of human MSA can be reproduced in the mouse model strengthening its role as a valuable testbed for studying selective vulnerability and assessing translational therapies

Integrating climate adaptation, water governance and conflict management policies in lake riparian zones: insights from African drylands

As river basin authorities and national governments develop policies to achieve sustainable development outcomes, conflicting signals between existing policies are undermining cross-thematic integrative modes of policy planning. This raises fundamental questions over how coherent portfolios of policy interventions across vital themes can best be advanced and managed. Taking the Lake Chad Basin (LCB) as an empirical example, we analyse transboundary policies and intervention documents relating to climate adaptation, water governance and conflict management to ascertain the interdependencies at the adaptation-water-peace nexus. Using a Qualitative Document Analysis (QDA) approach and a set of subjective integration scoring criteria, we assess whether and how integration is planned, setting out ways forward for mutually beneficial integration actions.Despite recent progress in addressing lake drying and recognising cross-thematic challenges, most LCB intervention plans continue to adopt standalone basin-scale agendas and seldom consider action plan preparedness based on local-level assessments. Analysis of a few (existing) cross-thematic, well-integrated initiatives indicates that the timings of societal challenges and funding arrangements appear to play a key role in shaping policy strategies, the manner in which climate adaptation, water or security are treated and the level of integration attained. Based on the notion that integration is inherently desirable, we suggest a new ‘policy integration thinking’ that embraces a development landscape logic and balances short-term and long-term development priorities

New Conceptions of Power Pulse Converters Using Extremely Fast Switching Semiconductors Based on SiC

Tato práce se zabývá problematikou pulzních měničů velkého výkonu (desítky kW) při použití nových polovodičů z karbidu křemíků (SiC). Nejprve je analyzován současný stav dané problematiky. Dále navazuje vlastní výzkum v konkrétní oblasti výkonových propustných měničů s pulzním transformátorem. Zde byl kladen velký důraz na minimalizaci rozměrů a hmotnosti. Při volbě detailů koncepce byly důležitými vodítky spolehlivost a robustnost. Aby bylo dosaženo definovaných cílů, bylo nutné použít nejnovější dostupné spínací tranzistory a diody a neobvykle velkou spínací frekvenci měniče (100 kHz při výkonu cca 16 kW). Díky tak vysoké spínací frekvenci bylo dosaženo malých rozměrů jak pulzních transformátorů, tak výstupních tlumivek. Dílčí samostatnou teoretickou oblastí práce byla optimalizace vysokofrekvenčního impulzního transformátoru s ohledem na minimální objem a hmotnost jádra a vinutí. Zde bylo provedeno několik analytických řešení optimalizačních úloh, jejichž výsledky by mohly mít přesah do realizační praxe v oblasti spínaných zdrojů. Kombinace velkého spínacího kmitočtu, rychlých polovodičů a velkého výkonu přináší nárůst různých parazitních jevů v silových obvodech měniče. V práci jsou tyto jevy detailně analyzovány. Řešení vedoucí k jejich minimalizaci případně úplnému odstranění byla teoreticky navržena a v experimentální části práce úspěšně realizována, ověřena a dále dopracována. Detailní popis realizace funkčního vzorku a série ověřovacích měření jsou uvedeny v závěrečné části práce.This work deals with high power pulse converters (tens of kW) using new semiconductor devices of silicon carbide (SiC). Firstly the current state of the issue is analyzed. A research in a specific area of high power buck converters with pulse transformer follows. There was a strong emphasis on minimizing size and weight. The design process was focused also on reliability and robustness. To achieve the defined objectives, it was necessary to use the latest available switching transistors and diodes, and an unusually high switching frequency (100 kHz at a power of about 16 kW). Due to the high switching frequency, we achieved small size of pulse transformers and output chokes. An optimization of high-frequency pulse transformer with demand on minimum volume and weight of core and windings represents a separate theoretical part of the thesis. There have been proposed several analytical solutions of optimization problems, the results of which could overlap with the implementation in practice of switching power supplies. The combination of high switching frequency, fast semiconductors and the high power brings various parasitic effects to the power circuit. In the thesis, these parasitic effects are analyzed. Solutions which minimize or completely remove those effects were theoretically designed and successfully implemented, tested and finalized in experimental part of the work. Detailed description of the implementation of functional sample and series of validation measurements are included in the final part.

Předpověď výnosu pšenice pomocí regresního přístupu

Tato bakalářská práce zkoumá použitelnost lineárních a stromových regresních modelů při predikci skutečného výnosu pšenice v Jihomoravském a Ústeckém kraji v České republice. Práce páruje družicové snímky Sentinel-2 s daty o výnosu po sklizni v jedné sezóně do mřížky 10x10m. Data o výnosech jsou rozdělena na percentilové a manuálně filtrované soubory dat. Ze satelitních snímků jsou extrahovány dva vegetační indexy, NDVI a EVI, které jsou použity jako primární nezávislé proměnné při trénování modelu. Některé modely používají jako nezávislé proměnné další proměnné po sklizni. K předpovědi skutečného výnosu se provádí jednoduchá a vícenásobná lineární regrese a stromová regrese s baggingem. Všechny modely ve všech souborech dat jsou porovnány pomocí standardních statistik R^2 Modely založené na silně filtrovaných souborech dat dosahují hodnot R^2 v horním rozmezí 0,92. Modely založené na méně filtrovaných souborech dat dosahují hodnot R^2 0,65. Průmyslová použitelnost zkonstruovaných modelů však vyžaduje další diskusi vzhledem k možným problémům (např. nadměrný fitting). Modely založené na stromech vykazovaly lepší výkonnost než lineární regresní modely. Ačkoli byly vnímány slibně, stromové modely se na daných datech neukázaly jako efektivní.This bachelor thesis explores the applicability of linear and tree regression models in predicting the true yield of wheat crops in the South Moravian and Ústí nad Labem regions in the Czech Republic. Thesis pairs Sentinel-2 satellite imagery with single-season post-harvest yield data into a 10x10m grid. Yield data are split into percentile and manually filtered datasets. Two vegetation indices, NDVI and EVI, are extracted from satellite imagery and used as the primary independent variables in model training. Some models use additional post-harvest variables as independent variables. Simple and multiple linear regression and tree regression with bagging are done to predict the true yield. All models across all datasets are compared using standard R2 and MSE statistics. Models based on heavily filtered datasets achieve R2 values in the upper range of 0.92. Models based on less filtered datasets achieve R2 values of 0.65. However, the industrial applicability of constructed models requires further discussion due to potential issues (e.g. overfitting). Tree-based models showed better performance over linear regression models. Although perceived promisingly, tree-bagging did not prove to be effective on the given data

Prefabricated Wall Panels Schedule and Cost Analysis

Plan BForms of prefabricated and module construction date back 2,000 years, however after the industrial revolution its efficiency started to increase. The quality of prefabricated components is superior to that of products built on-site. Construction working conditions are evolving from day to day as the building progresses from different stages of construction. This can cause many challenges, where prefabricated components are built in a factory setting with the most current technology. These components are then shipped to the jobsite for installation. In this study a cost and schedule analysis will be completed to show the difference in cost, schedule, and if the use of prefabricated wall panels improves the construction schedule which would result in monetary savings instead of a more traditional approach of stick framing walls

A real-time capable quasi-2D proton exchange membrane fuel cell model

In this paper a dynamic proton exchange membrane fuel cell model for real-time applications is presented. Following a quasi-2D approach, effects such as multicomponent diffusion in porous layers, membrane water transport driven by diffusion and electro-osmotic drag as well as membrane nitrogen crossover forced by partial pressure differences, are considered. A linearisation of the governing nonlinear equations with respect to the previous time step is applied to avoid numerically expensive Newton iterations and to speed up the simulation. Furthermore, a solution method based on Chebyshev collocation minimises the required number of nodes and assures real-time capability. The model is validated in terms of polarisation curves, current density and species distribution versus steady-state computational fluid dynamics simulations of a 3D fuel cell performed in AVL Fire (TM) . The transient behaviour is found to be in good qualitative agreement with results published by other authors. Due to the fast computation capability of the presented model, it is suitable for widespread parameter studies, control unit adjustments or state predictions, e.g. fuel starvation or membrane drying and flooding.6

Water governance and adaptation to drought in Guanacaste, Costa Rica

Capítulo de libro digital e impreso. Libro en la Base de datos Springer: Integrated Water Resource Management. Cases from Africa, Asia, Australia, Latin America and USA. pp 85-9.In this chapter we review the key learnings and challenges for water management in a territory where water is severely affected by climatic variability: the Guanacaste province in Northwestern Costa Rica. In this territory the water governance system is contested by the interaction of biophysical, cultural, and political factors, creating conditions for the emergence of disputes and enhancing the environmental and economic externalities from economic activities, mainly agriculture and tourism. We review the main factors from these intertwined dynamics to provide key lessons and identify sensible gaps in knowledge that need to be addressed in the upcoming research and integrated water resource management efforts. Our work shows that climate variability is increasing water demand, calling for a contextualized policy for managing water in Guanacaste. Moreover, the centralized, vertical, and fragmented water governance system led by the Central Valley region is imposing challenges for building up an adaptive governance system aiming for resilience at a long temporal scale. Despite the latter, several community-led experiences facilitated by boundary organizations and local champions suggest that water in Guanacaste can be secured by establishing multi-sectoral platforms for water adaptive governance and increasing the decision-making based on technical and scientific information.Centro Mesoamericano de Desarrollo Sostenible del Trópico Seco (CEMEDE)Centro Mesoamericano de Desarrollo Sostenible del Trópico Seco (CEMEDE-UNA)Universidad Nacional, Sede Regional ChorotegaUniversidad Nacional, Costa Ric