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Hydrodynamic mixing of water-ask mixture in vessel
Holub, Přemysl ; Franc, Zdeněk (referee) ; Habán, Vladimír (advisor)
Master´s thesis Hydrodynamic mixing of water-ash mixture in vessel is interested in describing fluid and solid particles flow in a vessel. The mixing was conducted in cylindrical vessel by a radial nozzle. The goal of the thesis is to describe flow field and places where the most of the particles are descending according to position, depth, flow rate and nozzle orientation in the vessel. An experiment was conducted in order to investigate and document 8 different positions and orientation of the nozzle. Significant changes in flow fields and mixing time were observed. A mathematical model of the vessel with the nozzle was created in Fluent program. Places with the lowest velocities according to the model were in good agreement with places where the most of the solid particles were descending.
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Belt conveyor
Konečný, Tomáš ; Pokorný, Přemysl (referee) ; Řezníček, Milan (advisor)
The aim of this bachelor's thesis is to propose design solutions conveyor belt to transport sand and gravel to concrete batch mixer. The maximum transport capacity 2000 kg/cycle, the cycle time benefits, including stirring for 4 min and 4.5 m height difference work contains a description of the main functional parts of the conveyor belt, functional calculations according to standard ISO 5048, determination of main dimensions, the design of the drive and tensioning devices. Strength calculation is performed for tightening screws, nuts and truss structures.
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The belt conveyor for transportation of aggregates
Němec, Petr ; Malášek, Jiří (referee) ; Kašpárek, Jaroslav (advisor)
This thesis deals with the concept of design solutions of conveyor belt. The aim of this work is to design a conveyor belt to transport gravel and gravel into three fractions by warehouse space, traffic performance of 50 000 kg• h-1, 4.5 m height difference. Design of the main dimensions, draft power and strength calculation of frame construction. Functional calculation is performed according to ISO 5048 of 1994. The work is accompanied by drawings.
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Design of rail vehicle sanding systems
Balounová, Hana ; Šperka, Petr (referee) ; Hartl, Martin (advisor)
The bachelor thesis deals with creating an overview of sanding systems, which are available on the marketplace in terms of their construction. Sanding devices are used in rail transport to incerase the adhesion during braking and moving off in bad weather condition. The thesis inculdes findings of testing influences of construction on the quality of sanding, list of companies producing sanders and their products and defining the future development trends.
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Shear strength of sand under very low normal load
Hudek, J. ; Koudelka, Petr
Solutions of some extraordinary geotechnical problems need knowledge of shear strength in a scale of very low normal stress. An example is physical modelling of soil mass behaviour using medium or little samples. The paper deals with results of testing a very dry uniform quartz sand of medium size. Resulting values of effective shear strength for the normal stress scale till of 25 kPa are compared with former testing of the same material in other scale of 63 – 163 kPa.
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Experimental heat flux declaration through soil or artifikal substrate using HFP01-SC sensor
VÁŇA, Jan
The aim of this thesis is to describe a method of measuring the heat flow through the substratum or soil with self-calibrating heat flux sensor HFP-01SC (Hukseflux, The Netherlands) and to confirm the appropriateness of its use. In addition, this paper should be a manual for applications using this sesnor. Submitted work should be a contribution to disciplines dealing with measurement of heat flow through the substratum or soil.
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An experimental study of initial succession on different substrata: analysis of changes in plant species cover and some soil biological parameters and their relationships
KRESÁČ, Martin
A four year experimental study of initial stages of succession on different substrata (sand, peat and gray clay overburden from brown coal mining) was carried out. The substrata were transplanted into two different landscape types in the Czech Republic. Control plots were filled with autochthonous topsoil treated with high temperature vapor. Plots with un-treated autochthonous topsoil were also established. Plant species cover and several soil-biological parameters (soil microbial biomass, basal soil respiration, exchangeable pH(KCl), organic-C extractable by potassium sulfate solution, and nitrate-N content) were measured once a year. Obtained data were mainly processed by unimodal (plant cover data) and liner (soil-biological data) ordination methods. Biological species traits (life span, seed dispersal vector, seed bank type, ecological strategy type following Grime, life form following Raunkiaer) were used to characterize early stages of plant succession. Vegetation and measured soil-biological parameters, except pH(KCl), were significantly changing during four growing seasons. Variance partitioning analysis based on plant species cover data indicated the landscape type to be the main governing factor and physico-chemical characteristics of substrate to be less important during the studied initial stages of succession. The same analysis based on soil-biological parameters showed the reverse result. Great variability of plant species ecological traits was noticed during four growing seasons. The earliest plant colonizers were mainly ruderal, anemochorous terophytes with persistent seed bank. The number of species with C-strategy type increased during the study. The relationship between the average plant species cover and measured soil-biological parameters was also examined during the experimental study of early succession. Direct and indirect ordination revealed the average sum of plant species cover to be weakly positively correlated with soil microbial biomass, basal soil respiration, nitrate-N, potassium sulfate extractable organic-C, metabolic quocient (qCO2) and negatively correlated to exchangeable pH(KCl). The relationship was significant only in the case of microbial biomass and potassium sulfate extractable organic-C. More detailed studies of the relationship between aboveground plant species biomass and soil microbial communities in initial stages of succession are required. Comparability of presented study is limited because not many experimental investigations of similar kind have been presented until now.
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Fly-ash mobility in sandy material
Kodešová, R. ; Kapička, Aleš ; Fialová, Hana ; Žigová, Anna ; Kočárek, M. ; Kopáč, J. ; Petrovský, Eduard
Fly-ash migration in three sands of various particle size distributions and consequently various porosities was studied in the laboratory. The fly-ash was applied on the top of all sands packed in plastic cylinders followed by pulse infiltrations. Water regime was monitored using the soil water content sensors SM200 and micro-tensometers T5. Kappameter SM400 was used to monitor migration of ferrimagnetic particles-tracers presented in the fly-ash. Undisturbed samples of sands polluted by fly-ash were taken at the end of the experiments to study final fly-ash distribution in section planes and thin sections of sandy material.
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