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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.
161

Vztah usilovné vitální kapacity plic a síly stisku ruky u dětí / Relationship between forced vital capacity and hand grip strength in children

Novák, Ondřej January 2017 (has links)
Title: Relationship between forced vital capacity and hand grip strength in children Objectives: One of goals of this thesis is to find out how strong is the connection between the strength of a children's handgrip and the FVC. Another aim is to ascertain what is the age limit to use a handgrip examination to estimate the children's FVC. The last goal is to determine whether a body height, weight and age of a child are crucial to evaluate the handgrip and the FVC. Methods: First part of this thesis is a research and tries to summarize basic information about an issue of dynamometry, spirometry and to characterize each of age brackets which are the main aim of this thesis. Second part of this work is a survey for which data from sport festivals for children and youth were assembled. This data were statistically processed to calculate correlation and to make graphs showing linear regression between observed variables (handgrip and FVC), finally the results were interpreted. Results: Between the handgrip and the FVC was proven a strong correlation (girls , boys ). It is possible to evaluate FVC with younger school age children from the value of handgrip's strenght. Values of strenght of a handgrip are strongly influenced by body length, weight and age of a child. Keywords: strenght of a handgrip, FVC,...
162

Analýza lomového chování elektronovým paprskem připraveného svaru oceli X5CrNiCuNb16-4 / Fracture behaviour analysis of the weld joint of the X5CrNiCuNb16-4 steel prepared by using an electron beam technology

Vaňhara, Vojtěch January 2017 (has links)
The diploma thesis is focused on the determination of the mechanical properties and fracture behaviour of the weld joint X5CrNiCuNb16-4 steel prepared by using electron beam technology. The theoretical part is based on summarization of the relevant information about welding, principle of electron beam welding and testing methods of welded joints. The experimental part of the thesis contains results of practical measurements and analyses, realized for evaluation of the mechanical and structural properties of the base material and weld.
163

Posouzení vlastností heterogenních tupých svarů metodami svařování laserem a svazkem elektronů / Assessment of heterogeneous properties butt welds in laser welding and electron beam welding

Rozsypal, Oldřich January 2015 (has links)
The project was developed within the engineering degree in engineering technology, and is focused in welding together of two different materials. Welds will be done on a high strength steel Domex 420 MC and deep drawing steel DC01 using laser welding, and will be compared with the method of electron beam welding. Part of this project is a scientific research describing the basic physical principles of both methods, different types of lasers, welding material properties and inspection of welds. In the experimental part was carried tensile test, macroscopic and microscopic examination. Finally, work is to evaluate the individual tests.
164

Studium odolnosti lepené spáry dřeva proti vyšším teplotám / Study of durability of wood glue bonds against increased temperature

Kučera, Vít January 2017 (has links)
In this time are for design of wooden elements available simplified procedures for fire modeling which defines ČSN EN 1991-1-2. But it is not experimentally tested the impact of adhesive on the final value of fire resistance of laminated panels. This diploma thesis solves basic normative practices that could explain the durability of glue bond against increased temperatures. in the practical part will be undertaken to experimentally assess the impact of various kinds of adhesive-based (epoxy, formaldehyde, PUR and EPI) on the glued bond durability against increased temperature. Glued joints that will be subjected to gradual temperature exposure in order to assemble the dependence of the temperature influence on the final strength of the joint according to the type of adhesive.
165

Resposta de células pulpares a biomodificação do colágeno pela acroleína e seu efeito sobre a resistência máxima a tração da matriz dentinária e resistência da união resina-dentina /

Gomes, Lays Nobrega. January 2020 (has links)
Orientador: Josimeri Hebling / Resumo: Objetivo: Investigar a citotoxicidade transdentinária da acroleína (ACR) sobre células pulpares e a resistência máxima à tração (RMT) da matriz dentinária e resistência da união (RU) resina-dentina após a biomodificação do colágeno dentinário por esse agente promotor de ligações cruzadas. Métodos: Discos de dentina (0,4 mm de espessura) foram obtidos de molares humanos hígidos e adaptados em câmaras pulpares artificiais. Células MDPC-23 foram semeadas na superfície pulpar desses discos e a superfície oclusal foi condicionada com ácido fosfórico por 15s. Sobre a dentina condicionada foi aplicado (n=9): água deionizada (controle), ACR 0,02%, 0,01%, 0,005%, glutaraldeído 5% (GD) ou peróxido de hidrogênio 3%. Após 60s, a superfície foi lavada e as câmaras foram incubadas por 24h. Foi avaliada a viabilidade das MDPC-23 (alamarBlue) aderidas na parede pulpar dos discos e os extratos foram aplicados em novas MDPC-23 e HDPCs (células da polpa dental humana) cultivadas em placas de cultura. Após 24h, essas células foram avaliadas quanto a viabilidade, atividade de fosfatase alcalina (ensaio da timolftaleína), presença de nódulos de mineralização (Alizarin red) e expressão gênica de ALPL, DSPP, MMP2, MMP9 e IL1B (PCRq). Vinte cinco molares adicionais foram seccionados para obter espécimes de dentina (n=50) que foram completamente desmineralizados com ácido fosfórico por 24h. Os espécimes de matriz dentinária foram tratados por 60s com: água, ACR 0,02%, 0,01%, 0,005% ou GD 5% e submetid... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Objective: To investigate the transdentinal cytotoxicity of acrolein (ACR) on pulp cells, as well as the ultimate tensile strength (UTS) of the dentin matrix, and the strength of resin-dentin bonds after dentin collagen biomodification with this cross-linker. Methods: Dentin disks (0.4 mm thick) were cut from sound human molars and adapted in artificial pulp chambers. MDPC-23 were seeded on the pulpal side of the disks and the occlusal surface was etched with phosphoric acid for 15s. The etched dentin was treated with (n=9): deionized water (control), 0.02%, 0.01%, 0.005% ACR, 5% glutaraldehyde (GD), or 3% hydrogen peroxide. After 60s, the surface was rinsed, and the chambers were incubated for 24h. The viability of MDPC-23 cells seeded on the disk was assessed (alamarBlue) and the extracts were applied on new MDPC-23 and HDPCs (human dental pulp cells) seeded in culture plates. After 24h, the viability of the cells was investigated as well as the activity of alkaline phosphatase, presence of mineralized nodules (Alizarin red) and ALPL, DSPP, MMP2, MMP9 and IL1b gene expression (qPCR). Additional twenty-five human molars were sectioned to obtain dentin specimens (n=50) which were completely demineralized in 10% phosphoric acid for 24h. The specimens were treated for 60s with: water, 0.02%, 0.01%, 0.005% ACR or 5% GD, and then submitted to a mechanical test to determine the UBS. Finally, flat dentin surfaces prepared in 40 human molars were etched with phosphoric acid and trea... (Complete abstract click electronic access below) / Mestre
166

Extrémní překážkové běhy / Extreme obstacle racing

Simandl, Radek January 2019 (has links)
Extreme obstacle racing is a brand new sporting industry that is currently developing most not only in Europe but also around the world. I focused mainly on introducing this new sport in order to find out different level of the motor skills of beginners and professionals. In the theoretical part of my work, I defined what is characteristic for this sport and why it is so famous and wanted today. In the practical part, using the proposed test battery, I tested all the motor skills of beginners and professionals in order to identify the real physical differences between them. As a result of these facts, methods of testing, observation, processing, evaluation, analysis and statistics of data, along with the study of professional literature, were used. Based on the established hypotheses, I asked questions that I had in my opinions and attitudes to the beginners and professionals of this thriving sport. Through research and testing, we have found that professionals are certainly more dominant in motor skills than beginners with overall predominance in all underlying motor tests that included speed, endurance, strength and coordination tests. The benefit of this work is the analysis and introduction of a new sporting industry, including the main discovery of real differences between beginners and...
167

Carbon nanotube membranes for brackish groundwater desalination and removal of organic micropollutants from water

Gumbi, Nozipho Nonsikelelo 07 1900 (has links)
This thesis reports on the synthesis and characterisation of various types of oxidised multiwalled carbon nanotubes (O-MWCNTs) modified polymeric membranes. These OMWCNT modified polymeric membranes were then assessed in terms of their remediation potential, in particular for the removal of estrogenic hormones, dissolved proteins and salts from brackish water sources. The fabricated O-MWCNT-based polyethersulfone (PES) membranes were applied as (i) adsorptive membranes, (ii) molecular-sieving membranes and (iii) as membrane substrates for thin-film composite nanofiltration (NF) membrane preparation. The research work commences with the preparation of MWCNTs via a facile catalytic chemical vapour deposition method and their chemical oxidation with strong acids in order to introduce hydrophilic carboxylic (–COOH) and hydroxyl (–OH) surface functional group moieties on the MWCNT outer walls. Intrinsically, MWCNTs are chemically inert and tend to form agglomerated nanoclusters (due to van der Waals interaction forces), which induce further difficulties in their homogenous dispersion in polar solvents (such as N-methyl-2- pyrrolidone and dimethylacetamide) employed to dissolve the polymers in the study. The introduction of these oxygen-containing moieties was therefore necessary to aid the dispersion of MWCNTs in organic solvents and for their enhanced interaction with PES and sulfonated polysulfone (SPSf). The PES/O-MWCNT ultrafiltration (UF) membranes were produced via a non-solvent induced phase separation (NIPS) method and employed in the adsorptive removal of natural hormone estrone (E1). The PES/O-MWCNT UF membranes thus prepared were characterised using SEM, AFM, zeta potential measurements and MWCO experiments. It was found that the adsorption of E1 initially increased with an increase in O-MWCNT content followed by a constant decline on further increments. Moreover, the inclusion of OMWCNTs (0.5 wt.%) in the PES membrane matrix resulted in an increase in the maximum adsorption capacity for E1 compared to pristine PES membrane, i.e., 31.25 mg/g adsorption capacity was achieved for PES/O-MWCNT compared to 23.81 mg/g for bare PES UF membrane. Based on the correlation coefficients, the Freundlich isotherm provided a better fit for the adsorption data and the adsorption kinetics followed the pseudo-second order kinetic model. Interestingly, after five regeneration cycles, the PES/O-MWCNT membranes were found to maintain similar adsorption efficiencies. The PES/O-MWCNT membranes thus prepared, present a viable approach for the removal of natural hormones and other endocrine disruptors present in water systems compared to the use of common adsorbents such as activated carbon, which end up generating large amounts of chemical sludge that require disposal in the environment. The third part of the study focused on the controlled formation of macrovoid-free polyethersulfone/sulfonated polysulfone (PES/SPSf) UF membranes with high water permeabilities, mechanical strength and antifouling properties, in the presence of O-MWCNTs. To date, the majority of polymeric nanocomposite membranes modified with O-MWCNTs as nanofillers, generally have finger-like structures and macrovoids in the membrane sublayer. While the presence of finger-like structures is favoured for the reduction in mass flow resistance, their presence induces mechanically weak points in the membrane and reduces the nanocomposite membranes’ mechanical strength properties and long-term performance stability. As such macrovoid-free PES/SPSf/O-MWCNT membranes were fabricated via the NIPS techniques, using H2O and polyethylene glycol (PEG 20 kDa) as non-solvent additives. The SEM cross-sectional images showed that a fully sponge-like morphology of the PES/SPSf membrane can be achieved in the presence of different loadings of O-MWCNTs. This was attributable to the formation of stronger hydrogen bonds between the SPSf polymer and non-solvent additives i.e., H2O, PEG 20kDa and OMWCNTs. The combination of the macrovoid-free morphology and homogenous distribution of high mechanical strength O-MWCNTs in the membrane matrix provided excellent mechanical strength enhancements for PES/SPSf/O-MWCNT membranes. Additionally, pure water flux initially increased from 598 L/m2 .h to 713 L/m2 .h followed by a decline to 578 L/m2 .h upon further increments in O-MWCNT contents, due to agglomeration of O-MWCNTs at higher loadings. The fabricated PES/SPSf/O-MWCNT membranes also displayed superior antifouling properties (FRR > 90%) and antibacterial properties (99% bacterial killing ratio) against E. coli bacteria. The fabricated support fabricfree PES/SPSf/O-MWCNT UF membranes with macrovoid-free sublayer morphologies displayed attractive features for use as UF membranes in the pre-treatment stages of water treatment and as support substrates for the preparation of TFC membranes. In general, sponge-like and macrovoid-free membrane structures are regarded as unfit for use as support membranes for TFC membrane preparation since they increase the membrane’s resistance to water flow, thereby reducing the overall TFC membrane permeability. This assumption has largely been based on sponge-like and macrovoid-free membranes structures achieved through the use of extremely high polymer concentrations, particularly using polysulfone (PSf) polymer. Hence, the sponge-like structures formed are very dense and less porous. Nevertheless, the macrovoid-free PES/SPSf/O-MWCNT membranes produced in this study, consisted of open cellular network microstructures within the membrane sublayer, which could be visualised at higher SEM magnifications. This part of the work therefore investigated the role of hydrophilic, macrovoid-free PES/SPSf and PES/SPSf/O-MWCNT as support membranes on the performance of TFC NF membranes. The TFC NF membranes were prepared via an efficient interfacial polymerization reaction between piperazine (PIP) and trimesoyl chloride (TMC). The deposition of the polyamide thin-film layer was confirmed by ATR-FTIR, SEM, AFM, contact angle and zeta potential measurements. Membrane performance results showed that TFC NF membranes fabricated on PES/SPSf/O-MWCNT support membranes displayed a 35% improvement in pure water flux with comparable salt rejections from those prepared on bare PES/SPSf support membranes. Salt rejection followed the order of Na2SO4 > MgSO4 > NaCl, which is typical for negatively charged NF membranes. It was established that the presence of hydrophilic O-MWCNTs in the support membrane allowed for the formation of a thin polyamide layer on the top surface of the support membrane, which gave rise to enhanced water permeability of the TFC NF membrane and the possibility of polyamide rejection layer within the support membrane pore channels. To further improve the performance of the TFC NF membranes, in particular, the monovalent/bivalent salt selectivity, a mixture of PIP and 2,4-diaminobenzene sulfonic acid (2,4-DABSA) at different weight ratios was prepared in the aqueous solution and reacted with TMC in the organic phase solution. It was found that the addition of low monomer weight ratio of 2,4-DABSA in the amine mixture, lead to the generation of a sulfonated TFC NF membrane with superior membrane performance in terms of pure water permeability (30.2 L/m2 .h), monovalent/bivalent salt selectivity (𝛼NaCl/Na2SO4 = 25.0) at low operating pressures (3 bar) and salt concentrations in the range of brackish waters. This was attributable to the combined presence of sulfonic acid groups on the membrane surface and the formation of the thin polyamide layer. Moreover, sulfonated TFC NF membranes exhibited good antifouling properties against bovine serum albumin (BSA), with FRR of 96.4% after three cycles of fouling and cleaning, with a fairly stable membrane performance over a 10-day period of pure water flux and Na2SO4 rejection testing. Indeed, the use of a macrovoid-free PES/SPSf/O-MWCNT support membrane did not only provide the mechanical strength for the deposition of TFC NF membrane, but also their open, cellular network microstructure, combined with high hydrophilicity and large surface pore sizes were beneficial in the reduction of polyamide layer thickness, and subsequently in the enhancement of TFC NF membrane performance. The study provided insightful information on lesser known aspects of O-MWCNT incorporated polymeric membranes, with regards to membrane structural configurations in relation to the membrane structure-performance relationships. It has been deduced that (i) the right combination of membrane surface characteristics and adsorbate solution chemistry is necessary for an open UF membrane to display reasonable removal efficiencies for low molecular-weight solutes, (ii) the combination of macrovoid-free membrane morphology with good dispersion of O-MWCNTs in the polymer matrix is necessary to realise significant enhancements in the mechanical properties of sulfonated membrane and (iii) formation of a thin sulfonated polyamide layer on top of the hydrophilic PES/SPSf/O-MWCNT support membrane is necessary to achieve high salt selectivity, and allow for the sulfonated TFC NF membrane to be operated at low pressures. / College of Engineering, Science and Technology
168

Směsný recyklát do podloží vozovek pozemních komunikací / Waste building material to subgrade pavement

Masař, Daniel Unknown Date (has links)
The theoretical part of the diploma thesis searches the production of Construction and demolition waste and their subsequent transformation into the final recyclate and its possible use in roads. Attention is focused on the use of mixed recycled material into subgrade of the pavement and the characteristics of tests that must be performed before its used to the road. The next chapters pai attention to the problematic properties of recyclates, foreign experience with the use of mixed recyclate in Construction and the possibilities of its development. The practical part verifies the suitability of mixed recycled material into subgrade of the pavement using laboratory tests. The tests are performer on individual mixtures of mixed recycled material with cement, blast furnace slag or cement dust in various percentages. The results are then compared and it is evaluated which mixtures show the best properties. Part of the practical part is also the economic evaluation of these mixtures against commonly used materials.
169

Hydratation d'un système cimentaire binaire contenant des cendres volantes de biomasse

Davidenko, Tatyana January 2015 (has links)
Résumé : L’utilisation des cendres volantes générées par la combustion de biomasse présente une solution très prometteuse pour la conception de bétons écologiques de haute performance. Cependant, leur comportement dans un milieu cimentaire est encore peu étudié. Ce projet est concentré sur la compréhension des processus d’hydratation d’un système cimentaire contenant les cendres volantes de biomasse disponibles localement. Lors du programme expérimental, la caractérisation physico-chimique des cendres volantes étudiées a d’abord été réalisée. Ensuite, leur effet sur les propriétés rhéologiques, la cinétique d’hydratation, l’évolution des hydrates avec le temps et le développement des résistances ont été examinés. Les systèmes étudiés sont des pâtes et des mortiers avec différents taux de remplacement de ciment par les cendres volantes et deux rapports eau/liant de 0,5 et 0,4 en absence et en présence de superplastifiant. La variation des propriétés physico-chimiques de différents échantillons des cendres volantes (finesse, teneur en chaux libre, en sulfates et en calcite) a été utilisée pour déterminer l’effet de chacun de ces paramètres sur les performances des mélanges. Le remplacement partiel du ciment par les cendres volantes de biomasse entraine des changements sur la rhéologie, la cinétique d’hydratation, la composition des hydrates et la microstructure des pâtes hydratées. De plus, certains problèmes de compatibilité entre les cendres volantes et les superplastifiants sont observés. En se basant sur l’analyse des résultats obtenus, les explications des phénomènes qui se produisent dans les systèmes cimentaires contenant les cendres volantes de biomasse sont proposées. / Abstract : The use of wastepaper sludge ash (WSA) represents a very promising solution for ecological high performance concrete design. However, the effect of WSA on cementitious systems properties is still insufficiently studied. The present project intends to understand the hydration process in Portland cement systems containing locally available WSA. The experimental program begins with characterization of WSA physico-chemical properties. Then, the effect of WSA on rheology, hydration kinetics, hydration products evolution over time and strength development in cement blends is investigated. The systems discussed here are cement pastes and mortars with different cement replacement by WSA ratio and two water to binder ratio (0,5 and 0,4) with and without superplasticizer. The variation of physico-chemical properties (fineness; free lime, sulphate and calcite content) between different WSA samples was used to determine the effect of each of these parameters on blended cement performances. Partial cement replacement by WSA leads to changes in rheology, hydration kinetics, composition of the hydrates and microstructure of hydrated pastes. Moreover, some incompatibility problems between WSA and superplasticizers used are observed. Based on experimental results analysis, the explanations of the phenomena taking place in cement systems containing WSA are proposed.
170

Myndigheters kund- och leverantörsrelation : En relations- och partnerskapsanalys mellan två försvarsmyndigheter

Virolainen, Heikki January 2016 (has links)
Som utveckling inom kvalitetsområdet är ett förslag att titta närmare på kund- och leverantörsförhållanden och hur de arbetar kvalitetsmässigt. Frågor som väckts är exempelvis hur man involverar kunden som en naturlig resurs i kvalitetsutveckling och hur nära man vågar släppa in kunden. Studien väljer att titta på de komplexa förhållanden som uppstår när myndigheter har en kund-/leverantörsrelation till varandra. Syftet med studien är att åskådliggöra kvalitetsarbete i relationen och partnerskapet mellan myndigheterna och föreslå framgångsfaktorer och ev. förbättringsförslag. En fallstudie genomfördes med två myndigheter som studieobjekt. Studien inhämtade ett triangulerat underlag via enkäter, intervjuer och styrande dokument för att analysera parternas relation, partnerskap och kvalitetsarbete mellan varandra. Det inhämtade underlaget stärktes av en kombination av kvantitativ och kvalitativ data. Resultatet visar att relationskvaliteten är till mestadels hög mellan parterna och partnerskapet som finns mellan dem är uttalat och strategiskt formulerat. Studien visar på en styrkepositionering mellan parterna som i kombination med de bindningar som finns mellan dem ger ett utfall på att en av parterna har en dominerande roll inom partnerskapet. Studien åskådliggör befintliga strukturer för kvalitetsarbete mellan parterna och lyckas utvinna framgångsfaktorer som föreslås kunna gälla även för andra myndigheters kvalitetsarbete i liknande kund-/leverantörsrelationer mellan varandra. / It´s suggested, as development in the quality area, to look closer at customer and supplier relationships in terms of how they´re working with quality in the relation. Questions raised, is as example, how to involve the customer as a natural resource in quality development, and how close suppliers dare to let the customers in. The study chooses to focus on the complex relationship arising when governmental agencies have customer/supplier relationships and partnerships with each other. The purpose of the study is to reveal how the governmental agencies work to improve quality in their relationship and partnership, and to suggest success factors as well as areas for improvement in the relationship/partnership. A case study was conducted involving two governmental agencies. The study retrieved a triangulated information base through surveys, interviews and governing documents to analyze the two parties’ relationship, partnership and quality work between each other. The retrieved information base was supported by combining quantitative and qualitative data. The result of the study shows that the relationship quality is mostly high between the two parties, and the partnership between them is strategically phrased. The study reveals of a strength positioning between the parties that, when combined with present bonds, gives an outcome that one of the parties hold a dominating role within the partnership. The study illustrates existing structures for quality development between the parties, and is able to extract success factors that propose that other governmental agencies might be able to use in similar customer/supplier relationships between each other.

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