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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Analysis of Aeronautical Composite Structures under Static Loading / Analysis of Aeronautical Composite Structures under Static Loading

Cejpek, Jakub January 2018 (has links)
Poměrně velké množství soukromých firem v České republice vyrábí lehká sportovní letadla. Značná část těchto letadel využívá kompozitní pružiny ve svých přistávacích zařízení. Tyto pružiny jsou buďto menší díly, absorbující energii (na příďové noze či ostruze), anebo jde celé pružnice hlavního podvozku. Všechny tyto pružiny sdílí základní charakteristiky: jsou vyrobeny převážně z jednosměrného kompozitu s významnou tloušťkou, hlavním druhem zatížení je ohybový moment a jsou očekávány velké deformace. Podobnou charakteristiku můžeme použít i při popisu hlavního nosníku křídla. Jak vypadá návrh a analýza takovýchto dílů? V zásadě jsou dvě možnosti. První z nich je poměrně jednoduchá analytická analýza, případně naprogramovaná v tabulkovém výpočetním prostředí. Nevýhody tohoto řešení jsou limitované možnosti výpočtu a jeho nízká flexibilita. Druhou možností je využít komerční konečno-prvkový systém pro analýzu, případně i pro optimalizaci. Pochopitelnou nevýhodou této možnosti je cena programu a obsluhy. Cílem této disertační práce je vytvořit program, jež nabídne třetí možnost, která umožní provádět zevrubnou analýzu řešených produktů bez nutnosti pořizovat nákladný software. Tento program zjednoduší a urychlí návrh a pevnostní kontrolu. Umožní uživateli rychle analyzovat více návrhových variant. Program dále bude zohledňovat specifika analyzovaných produktů (například velké deformace a lokální koncentrace napětí kolmo na vlákno). Z pohledu uživatele by program měl být jednoduchý na ovládání. Minimum množství vstupních dat a přehledné grafické rozhraní zajistí komfortní používání. Samostatně spustitelný program (bez instalace a bez podpůrného softwaru) zlepšuje rozšiřitelnost programu.
22

Návrh změny kostrukčního řešení hlavních závěsů křídla letounu Z 242 / Design of new konception of the structural design of the main wing hinges of the Z 242

Hála, Aleš January 2020 (has links)
This diploma thesis deals with modernization of the Z 242 L aircraft wing. The main emphasis is given to the connection of the wing and fuselage. The new concept of both main and rear wing spar is designed together with integral fuel tank. The strength of the structure is evaluated analytically and numerically by use of Finite element analysis. Wide range of milling operations is implemented into manufacturing process as well. This thesis shows how to innovate current aircraft with respect to feasibility of the design in case of future project realization.
23

Pevnostní analýza nosníku s tenkou stojinou - vliv otvorů a tahového pole / The Stress Analysis of the Beam with Thin Web - Influence of the Holes and Tensile Effect of Web Buckling

Horák, Marek January 2014 (has links)
In design of an aircraft structure, the great emphasis is placed on achieving high weight efficiency. This thesis is focused on the stress analysis of the spars with thin web with or without web openings, which is one of the most important parts of the airplane structures. In comparison with traditional spars or beams, which are widely used in civil engineering applications, the design of the beam with thin web is more complicated. Thesis contains useful information for analytical calculation of this type of spars and its verification using finite element method and experimental measurement.
24

The Role of Calcineurin in Dendritic Remodeling and Epileptogenesis in a Rat Model of Traumatic Brain Injury

Campbell, John 14 February 2012 (has links)
Traumatic brain injury (TBI), a leading cause of death and disability in the United States, causes potentially preventable damage in part through the dysregulation of neural calcium levels. This dysregulation likely affects the activity of the calcium-sensitive phosphatase, calcineurin, with serious implications for neural function. To test this possibility, the present study characterized the role of calcineurin in a rat model of brain trauma, the lateral fluid percussion injury model. Golgi-Cox histochemistry revealed an acute post-TBI loss and delayed overgrowth of dendritic spines on principal cortical cells. The spine loss appeared to require calcineurin activity, since administering a calcineurin inhibitor, FK506, 1 hour after TBI prevented the spine loss. Additional experiments showed how calcineurin activity might be related to the spine loss. Specifically, Western blots and enzyme activity assays revealed an acute increase in the cortical activity of calcineurin and its downstream effector, the actin-depolymerizing protein, cofilin. The cofilin activation was blocked by the same FK506 treatment that prevented spine loss, suggesting a relationship between cofilin activation and spine loss. To investigate long-term consequences of calcineurin activation after TBI, rats were administered FK506 (Tacrolimus) 1 hour after TBI and then monitored for spontaneous seizure activity months later. Acute post-TBI treatment with FK506 reduced the frequency of late non-convulsive seizures but did not prevent late convulsive seizures, cortical atrophy, or thalamic damage. The results of the present study implicate calcineurin in the acute dendritic remodeling and late non-convulsive seizures that occur after TBI. Importantly, these findings reveal calcineurin as a potential therapeutic target in the treatment of TBI and its sequalae.
25

Prodloužení životnosti letounů ZLIN Z 126 a 226 / Safe-life extension program for ZLIN Z 126 and 226 airplanes

Jančář, Milan January 2012 (has links)
This master's thesis discusses the possibilities of safe-life extension program for ZLIN Z 126 and 226 airplanes, which despite their age and long-end production are still widespread and popular not only in the Czech Republic. The age of these aircraft is also related to the fact, that some aircraft are already approaching its border life, so there is an interest for the longest possible technical and legislative airworthiness. As mentioned in my bachelor's thesis, during the existence of this model series, there was no major damage occurred, except for sporadic exfoliation corrosion of wing flanges. Experience with maintenance of this aircraft points to certain underestimation of the current 5500hrs lifetime and it is obvious to suggest possible steps to increase the current limit. The thesis is therefore considered in this context the possibility of producing new wing flanges made of another material, performed the calculation for wing fatigue exchanged with flanges and designed technological process of this exchange, so that ZLIN Z 126 and 226 airplanes can be safely operated in the future.
26

Vybrané části stavebně technologického projektu fotbalové tribuny Androva stadionu v Olomouci / Selected Parts of Building and Technological Project for Football Tribune of Ander Stadium in Olomouc

Garláthy, Michal January 2013 (has links)
The theme of this diploma thesis are the Selected Parts of Building and Technological Project for Football Tribune of Ander Stadium in Olomouc. The content of this diploma thesis is the technological process of assembly of the building bearing construction of prefabricated concrete elements, the budget, the inspection and the test plan, the issue of safety and health at the construction site, the project concerning the construction site installation, the mechanical assembly, assessment of tower crane, object time and financial plan, construction technology study and the construction timetable.
27

Stavebně technologický projekt sídla firmy Snowboard Zezula / Construction technology project of Company Snowboard Zezula

Němec, Martin January 2014 (has links)
In this master´s thesis I am focusing on the Construction technology project of Snowboard Zezula Company. Major part of my thesis informs on a technical report for a construction technology project, a time and a financial plan of a construction, a realization study of the main technological stage, a plan of the main construction mechanism, a project of a construction site device with drawings, a financial calculation of the construction site devices and some technological rules, checking and testing plan for designed operations. Lastly I compare the two different designs of a load-bearing construction level and I calculate time of sheat removing with the economical calculation of the work fissure number.

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