National Repository of Grey Literature 1,052 records found  1 - 10nextend  jump to record: Search took 0.11 seconds. 

Two parameter fracture mechanics: prediction of the direction of crack growth
Seitl, S. ; Knésl, Zdeněk
Influence of constraint (as expressed by the T-stess) on predicting the direction of a crack growth is investigated and discussed for cracks under mixed-mode load condition.

Evaluation of elastic parameters for models of isolated cells
Krbálek, Jaroslav ; Fuis, Vladimír (referee) ; Burša, Jiří (advisor)
This diploma thesis focuses on computational modeling of the cell mechanical tests. The goal of this thesis is to build a cell model and to simulate compression test on this model. If necessary, the model should be adjusted so the model reflects real cell behavior. It was created the cell model reflecting cytoplasm, nucleus, membrane and cell cytoskeleton. Cytoskeleton was modeled as tensegrity structure. After this, the pressure test was simulated on this model. The behavior of the cell model and real cell was compared using the stress force. The stress force - cell deformation curve was markedly different for the cell model and the real cell. For this reason, the cytoplasm material model was adjusted. The difference between the curves was acceptable after this modification. It was found during computations that the cytoskeleton model influence on the cell load is minimal. These results does not reflects real cell behavior, which means that the model is considered inadequate for performing stress load simulation.

Parametrical study of the stress changes in the pelvis bone after hemiarthoplasty
Kytýř, Daniel ; Jírová, Jitka ; Micka, Michal
Article deals with development and utilization of parametrical FE model of pelvic bone for analysis of migration of implant head after hemiarthoplasty. The CE angle and direction of loading were taken as imput parameters for the stress analysis. The analysis was carried out as axially symmetric 2D contact problem. Extreme values of first principal stress, third principal stress and sum of displacements were used as a reference magnitude.

Vodní a hybridní plazmatrony s plynovou a vodní stabilizací
Hrabovský, Milan
Plasma torches with water-stabilized arc (Gerdien arc) are utilized in plasma processing for specific applications. In water-stabilized torches an oxygen-hydrogen plasma jet is produced. The torches are characterized by very low mass flow rates and high power. Plasma enthalpy is thus several times higher than enthalpy of plasmas generated in gas-stabilized torches. High enthalpy is accompanied by very low plasma density. Also other plasma parameters substantially differ from the ones in gas torches. New type of plasma torch with combined stabilization of an electric arc by water vortex and gas flow was investigated. This hybrid water/gas stabilization offers possibility of adjustment of plasma jet parameters in a wide range from high enthalpy, low density plasmas typical for liquid stabilized torches to lower enthalpy, higher density plasmas generated in gas stabilized torches.

Analýza metabolických a reprodukčních ukazatelů ovcí ve vybraném chovu plemene suffolk
OUŘEDNÍKOVÁ, Kateřina
The aim of the study was to analyze the reproductive, productive and metabolic values of ewes from selected parameters in blood, milk and urine in correlation to their metabolic state. The results were used to draw up new breeding and feeding schemes. The research was carried out in 2015, and the sample size consisted of 62 Suffolk ewes. The analysis of reproductive parameters of selected ewes confirms appropriately chosen breeding methods. The average weight of lambs at birth (3,82 kg) is affected by the number of lambs at birth. The average weight of lambs at 100 days of age (32,54 kg) depends on the number of lambs per ewe and the age of ewe. The average daily weight gain makes 0,325 kg per lamb. Lowered concentration of proteins related to the decreased level of urea in the blood plasma signifies insufficient intake of nitrogen of ewes from feed.

Comparison of Business Intelligence implementation using open source solutions for middle size companies
Schmidt, Róbert ; Maryška, Miloš (advisor) ; Sládek, Pavel (referee)
The main goal of master thesis is to analyze and propose possible low cost Business Intelligence solution with open source technologies and comparison of available tools for implementation in middle size company. We compare Pentaho and Jaspersoft tools implemented on local hardware and cloud environment with Microsoft Azure services. The theoretical part focuses mainly on understanding the business intelligence and its architecture, because architecture is an important part of the work. Actual tools are designed as stand alone modules for specific activities in the business intelligence lifecycle. Low cost tools are often connected with open source technologies and cloud computing. This part of the work contains explanation of these terms and their advantages and disadvantages for our chosen target group of companies. The analytical part includes defined parameters by which it is conducted analysis of tools and their comparison. Business Intelligence solutions are divided according to arcitectural layers. The evaluation criteria are divided into financial, technical and user category. In conclusion, chosen tools are compared and evaluated. The main contribution of this thesis is comparison of open source business intelligence tools for implementation in middle size company. According to the EU directive, middle size company does not exceed 250 employees or profit is less than 50 million euros. The reader can compare the different solutions and their pitfalls or shortcomings that could be critical for the implementation.

HYDROGEN ABSORPTION IN A-Co30Fe55B15
Čermák, Jiří ; Král, Lubomír ; Roupcová, Pavla
Hydrogen solved in amorphous alloys (AAs) influences their magnetic characteristics. AAs are also perspective\nas additives that can improve hydrogen storage kinetic in certain types of ball-milled hydrogen storage\nmaterials (HSMs). Therefore, knowledge of hydrogen solubility and hydrogen sorption kinetics in AAs are of a\ngreat importance for aimed design both AAs with optimal magnetic parameters and HSMs with desired sorption\ncharacteristics. In the present paper, amorphous alloy Co30Fe55B15 (an example of the type a-TM1xTM2y Bz ;\nTM - transition metal) was investigated. Hydrogen concentration c H was measured by Sieverts method in\ntemperature interval from T = 150 °C to T = 350 °C under hydrogen pressure p up to 6 MPa. It was found that\nc H was an increasing function of p and its maximum value was typically 0.5 wt.% H2 at 350 °C and 6 MPa.\nHowever, when the alloy was preliminary hydrogen charged (PHC), the pressure dependence of total c Htot in\nthe first absorption cycle(s) is non-monotonous in dependence on PHC conditions. For the sake of comparison,\nthe same absorption characteristics were measured also in Mg2Ni intermetallic that is a common constituent\nin Mg-based HSMs. Comparing Co30Fe55B15 and Mg2Ni, it was concluded that Co30Fe55B15 shows lower\nhydrogen solubility, but much better absorption kinetics.

Horizontal driven roller conveyor
Kozelek, Petr ; Malášek, Jiří (referee) ; Kašpárek, Jaroslav (advisor)
This thesis deal with the construction proposal of driven horizontal roller conveyor for transportation of europallets with loads 175 kg. Part of this thesis is functional calculation of roller conveyor, determination of main parameters of conveyor, calculation of solidity of shaft and shell of driving roller, design and control of frame. The thesis contains drawing documentation of conveyor assembly, conveyor section assembly, driving roller assembly and detailed drawings of shaft and shell of driving roller.

NUMERICAL SUPPORT FOR SPECIMEN LOADED BY BENDING AND WEDGE SPLITTING FORCES FOR MEASUREMENT OF CONCRETE PROPERTIES
Seitl, Stanislav ; Liedo, R. ; Holušová, T.
Fracture mechanical properties of silicate based materials are performed from various fracture mechanicals tests. For evaluation of parameters, the knowledge about calibration and compliance function is so important. Therefore, in contribution the compliance and calibration curves for a novel test based on combination wedge splitting test (WST) and three-point bend test (3PBT) are introduced. These selected variants exhibit significantly various stress state conditions at the crack tip, or, more generally, in the whole specimen ligament.

Influence of process parameters in forward extrusion on the die loading
Pokorná, Jana ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
One of the decisive factors of effective using of forward extrusion technology is lifetime of forming tools. Die is very loaded forming tool which loading and therewith related lifetime can be significantly affected by its construction. Construction also affected quality of extruded material. Finete element method allows to simulate this process and assess force which is needed to extrusion and state of stress in die and extruded material. Numerical simulation was realized in program ANSYS 11.0. Influence of reduction, angle of reduction, lenght of extruded material, rounding transition of die parts, extruded material and friction coefficient on die loading and emergence of cracks in extruded material was set in this diploma thesis. Results can be used to die construction optimalization.