Waste management in ceramics workshop of High School of Applied Arts - Course of study Ceramics and porcelain design

Katedra pedagogikyPedagogická fakultaFaculty of Educatio

Welding Galvanized and Austenitic Plates in the Serial Production

Import 05/08/2014Diplomová práce se zabývá hodnocením kvality svařované součásti. Svařenec se skládá z austenitického a pozinkovaného plechu a je proveden metodou odporového bodového svařování. Úkolem diplomové práce bylo optimalizovat proces svařování s cílem minimalizace počtu vad. V teoretické části je charakterizována metoda odporového bodového svařování a její vliv na svařitelnost jmenovaných materiálů. Experimentální část je rozdělena na dvě části. V první části je charakterizován počáteční stav svařování a vady vzorků. Druhá část se zabývá nastavením nových svařovacích parametrů a následným vyhodnocením kvality provedených svarů. V závěru práce je navržen postup zkoušení kvality svařence nedestruktivní zkouškou a možné další postupy optimalizace.The master thesis deals with the evaluation of the quality of a welded component. The weldment consists of austenitic and galvanized plate and it is made using the method of point resistance welding. The task of master’s thesis was to optimize the welding process in order to minimize the number of defects. The theoretical part is characterized by resistance spot welding and its effect on the weldability of these steels. Experimental part is divided into two parts. The first part is characterized by an initial state welding defects and samples. The second part focuses on the setting of new welding parameters and subsequent evaluation of the quality of the welds. In conclusion, the proposed procedure for testing the quality of weldments nondestructive examination and possible further optimization practices.345 - Katedra mechanické technologievýborn

MECHANICAL TESTING AND NUMERICAL MODELLING OF POROUS STRUCTURES IMPROVING OSEINTEGRATION OF IMPLANTS

Implants, such as dental, are ordinary devices in medical care nowadays, even though they are quite expensive. In the present study, the use of trabecular and gyroid structures as external layer of implants is examined. The advantage of porous structures compared to surface modification of compact implants is the possibility to be fabricated by additive manufacturing together with the whole implant. The additive manufacturing also allows us to produce various shapes with controlled porosity for bone ingrowth. The design of 6 types of trabecular and 4 types of gyroid structures is part of the study. The trabecular structures are strut-based, whereas the gyroid structures are based on a wall system. The study is focused on mechanical testing of samples which were 3D printed from the titanium alloy Ti6Al4V. The gyroid structures, which we evaluated as more reliable, were chosen for numerical modelling. Other observed advantages and disadvantages of the structures are also discussed

Eurasian otter (Lutra lutra) density estimate based on radio tracking and other data sources

Estimating animal population size is a critical task in both wildlife management and conservation biology. Precise and unbiased estimates are nonetheless mostly difficult to obtain, as estimates based on abundance over unit area are frequently inflated due to the Bedge effect^ bias. This may lead to the implementation of inappropriate management and conservation decisions. In an attempt to obtain an as accurate and conservative as possible picture of Eurasian otter (Lutra lutra) numbers, we combined radio tracking data from a subset of tracked individuals from an extensive project on otter ecology performed in Southern Portugal with information stemming from other data sources, including trapping, carcasses, direct observation of tagged and untagged individuals, relatedness estimates among genotyped individuals, and a minor contribution from non-invasive genetic sampling. In 158 km of water network, which covers a sampling area of 161 km2 and corresponds to the minimum convex polygon constructed around the locations of five radio-tracked females, 21 animals were estimated to exist. They included the five radio-tracked, reproducing females and six adult males. Density estimates varied from one otter per 3.71–7.80 km of river length (one adult otter per 7.09–14.36 km) to one otter per 7.67–7.93 km2 of range, depending on the method and scale of analysis. Possible biases and implications of methods used for estimating density of otters and other organisms living in linear habitats are highlighted, providing recommendations on the issue

VERIFICATION OF BEHAVIOUR OF HUMAN ENAMEL FOR FRACTURE TOUGHNESS DETERMINATION

Enamel is the hardest biological tissue in the human body because of its structureand composition. The structure of interlocking rods enables this biomaterial to resist the stresses of mastication. Unfortunately, enamel is prone to fracture initiation and growth. Determining fracture toughness of enamel is a difficult task. The lack of thickness makes it impossible to prepare samples which could be analyzed by usual methods. Other authors use Vickers indentation fracture test (VIF) to determine fracture toughness of enamel ordinarily. VIF is, however, not generally acceptable.The aim of this study is verification of fracture behaviour of enamel using nanoindentation. In the study the impact of changes of hardness (HIT) and reduced modulus (Er) caused by crack initiation and growth on fracture toughness determination is observed. The next goal is evaluation of loading rate impact.</p

Evaluation of Walnut Tree Flowering and Frost Occurrence Probability During 1961-2012

Strength and direction of the potential effect of climate change on walnuts is regionally specific (Gauthier and Jacobs, 2011) as climate change will probably affect the spatial distribution of the walnut. This paper evaluated the long-term phenological series (1961-2012) of the beginning of flowering, end of flowering and duration of flowering in walnut tree (Juglans regia) at two phenological stations located in different geographical locations of the Czech Republic but in the same climatic conditions (warm region). Phenological stages were analyzed in relation to growing degree days and to spring frosts occurrence. Onset of the beginning and end of flowering occurred earlier at Velké Pavlovice station (-2.1 and -1.3 days), and conversely occurred later at Doksany station (+1.8 and +1.0). Period of flowering shortened at Doksany station (-0.8 day) and prolonged at Velké Pavlovice station (+1.2 day). The occurrence of days with minimum air temperature &lt; 0 oC during walnut tree flowering was more frequent at Doksany station (in total, 29 days) with absolute minimum value -5.5 oC. At Velké Pavlovice station 5 days with minimum air temperature below 0 oC were found during examined period with absolute minimum value -3.8 oC. The negative trend in number of frost days occurrence during flowering period was found at both stations. Pearson correlation coefficient between phenophase onset (and flowering period) and sums of growing degree days was stronger at Velké Pavlovice station, and the highest value was between period of flowering and temperature sums (0.782). The results confirmed our hypothesis of changes in phenophase onsets and duration of flowering including spring frosts occurrence according to west-east gradient (maritime climate-continental climate).O

Patterns of bryophyte and vascular plant richness in European subalpine springs

The diversity of spring habitats can be determined not only by local environmental conditions, but also by large-scale biogeographical effects. The effects can differ across various groups of organisms. We compared α-, β- and γ-diversity patterns of bryophytes and vascular plants of (sub)alpine springs in three contrasting mountain ranges: Alps (Switzerland), Balkans (Bulgaria), Western Carpathians (Slovakia, Poland). We used univariate and multivariate statistics to test for the effects of pH, conductivity, altitude, slope, mean annual temperature and annual precipitation on diversity patterns of both taxonomic groups and compared diversity patterns among the regions for particular pH and conductivity classes. We identified acidophyte and basiphyte, calcifuge and calcicole species using species response modelling. All regions displayed significant relationship between conductivity and α-diversity of vascular plants. Bulgaria showed the highest α-diversity of vascular plants for the middle part of the conductivity gradient. For both taxonomic groups, the β-diversity in the middle part of gradient was highest in Swiss Alps. The total species pool was lowest in Bulgaria. The percentage of basiphyte and calcicole species was highest in the Alps. In (sub)alpine springs, mineral richness was a better determinant of vascular plant α-diversity than pH, and the extent of the alpine area did not coincide with α-diversity. Observed inter-regional differences in diversity patterns could be explained by the different proportion of limestone bedrock and different biogeographic history. The differences in α-diversity between both taxonomic groups are presumably result of the different rates of adaptation processe

Electric Resistance Welding of Austenitic and Galvanized Steel Sheets

Nowadays the automotive industry is predominantly using heterogeneous welded joints. The welding of an austenitic and galvanized steel sheet is one of the most common applications, which are using resistive spot welding (RSW); it is a process in which contacting metal surfaces are joined by the heat obtained from resistance to an electric current. The electrodes used influence the quality of a heterogeneous welded joint. This paper describes the influence of the electrodes used, their material and shapes, and the final heterogeneous welded joint, which consists of two or three sheets. They will be compared with each other two electrode materials: CuCr1Zr original (material used for both electrodes) of new material CuCr1Zr (upper electrode replacement) and CuCo2Be (removable bottom electrode). Furthermore, the improved electrode geometry where the original planar electrode is passed to the electrode with radius surface, due to poor access to the point of welding. The aim of this research was to achieve a better quality of spot welded joints consisting of two or three sheets

GEOMETRY AND MECHANICAL PROPERTIES OF A 3D-PRINTED TITANIUM MICROSTRUCTURE

Construction applications sometimes require use of a material other than construction steel or concrete – mainly in cases, where strength to weight ratio needs to be considered. A suitable solution to this problem are structures manufactured using the 3D printing process, as they have a very good strength to weight ratio (i.e.: Ti-6Al-4V – σult = 900 MPa and ρ = 4500 kg/m3). Trabecular structures are porous structures with local material characteristics identical to their commonly manufactured counterparts, but due to their geometry, they have different global mechanical properties and are suited for special applications. We designed and manufactured six variants of these structures and subjected them to uniaxial compression tests, nanoindentation tests and subsequently evaluated their differences and elastic moduli. The values of global moduli E are in the range of 2.55 GPa – 3.55 GPa for all specimens

A core set of microsatellite markers for conservation genetics studies of Korean goral (Naemorhedus caudatus) and its cross-species amplification in Caprinae species

In order to screen microsatellites for conservation genetics studies of the species, a total of 23 microsatellite loci from Korean goral (Naemorhedus caudatus), including 15 previously developed loci and 8 new loci in this study, were tested. Eleven microsatellites were screened and subjected to cross-species amplification using a test panel of four Caprinae species, Japanese serows (Capricornis crispus), Chinese gorals (Naemorhedus goral), Northern chamois (Rupicapra rupicapra) and domestic goats (Capra hircus). In addition, all eleven microsatellites (SY3A, SY12A, SY12B, SY48, SY58, SY71, SY76, SY84, SY84B, SY112, and SY129) satisfied the criteria to be a core set of microsatellites. This core set of microsatellites and cross-species amplification of Korean goral microsatellites were found to be helpful for high-resolution studies for conservation and management of Korean goral and other endangered Caprinae species