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Host Specialization and Evolution of Cuckoo Behavior in Bees
Policarová, Jana ; Straka, Jakub (advisor) ; Orr, Michael Christopher (referee) ; Litman, Jessica (referee)
Cuckoo bees are nest parasites of solitary and sometimes also social bee species. They do not build their own nests. Nor do they provision their larvae. Instead, they seek out a suitable host nest to lay their eggs in, and their larvae then feed on the host's provisions. In this doctoral thesis, I examined the host specialization of cuckoo bee species. I focused on the evolution of host specialization of cuckoo bees and factors which may limit their host choice - specifically whether and how are cuckoo bees affected by host food specialization. Answering these questions required phylogenetic reconstruction of several cuckoo bee lineages. We produced the first phylogenetic reconstruction of the tribe Sphecodini (Halictidae) and revised the taxonomy of the lineages Neolarrini, Biastini and Townsendiellini (Apidae), merging them into a single tribe Neolarrini. Lastly, we reconstructed the phylogeny of the mainly Palaearctic species of the genus Nomada, on the basis of which we divided the Nomada species into 13 subgenera. The mapping of ancestral character states showed that cuckoo bees of the genus Sphecodes change hosts quite frequently during evolution and are able to switch to phylogenetically distant hosts from different families. It also appears that there is no evolutionary trend towards...
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Production of screw-thread in small engineering company.
Straka, Jiří ; Prokop, Jaroslav (referee) ; Kalivoda, Milan (advisor)
This work, wrought in branch of engineering technology in terms of baccalaureate studies, mentions the basic type partitioning of screw threads and their screw-threads labelling. There are presented some possibilities of screw threads manufacturing by chip-forming operation and by chipless machining operation, both with using of appropriate tools. Further the methods of production used in small machine-works are described. In this case the small machine-works is represented by secondary technical school.
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Technology of production part
Straka, Jiří ; Dvořák, Milan (referee) ; Osička, Karel (advisor)
This diploma thesis is developed within my Master’s degree studies, branch mechanical engineering (M21 K), and specialization in M STM. The aim of this thesis is to solve the technology of mechanical production (machining, tooling) for the machine component called ‚shape lid‘. I execute the analysis of this technology from the perspective of the conventional machining process, and alternatively, some of the non conventional machining process, too. Conventional machining process is so far used for manufacturing of this sort of machine’s element. It‘s implying laborious work difficulties, even it’s economically disadvantageous. I suggest a new technology of manufacturing. At first, a semi-finished component could be sized by conventional machining process, and then it could be finished by the CNC (computer numerical control) milling machine. By the non-conventional machining process assume the usage of an electro-erosive machining, plasma machining, or water jet machining.Conventional technology suppose the usage of CNC milling machines. Thereinafter, feasibility aspects of this brand new technology are considered in technical and economical perspective.
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Lithium battery accumulation system testing
Straka, Jan ; Koval, Filip (referee) ; Morávek, Jan (advisor)
This bachelor thesis deals with properties, parameters and testing of lithium battery systems available on the market. It describes basic parameters of battery cells, which are used to make batteries and battery systems, equivalent electrical models of batteries for the purpose of conversion of their properties to an electrical circuit and stating and comparing commercial battery systems of different manufacturers. What follows is the introduction of tests to measure the parameters of battery systems. The experimental part of this thesis describes the used testing platform and evaluates results of carried out measurements.
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Proposal of shearing tool for the manufacture of shaped blank
Straka, Jan ; Řiháček, Jan (referee) ; Peterková, Eva (advisor)
The thesis presents a design of a progressive cutting tool for the production of shaped blanks from sheet metal Usibor 1500 (22MnB5) with a thickness of 1.5 mm. The tool is designed by using CATIA V5 software in cooperation with Žďas, a.s. company. Based on the literature review of the cutting process, cutters were designed, shear clearance and order of operations in the tool were determined. The proposed cutting tool consists of both manufactured and standardized parts. Tool parts fall out of the chute onto the conveyor belt. The tool is designed to operate on an AIDA 1000 excentric press with a nominal force of 10,000 kN. Cutters that are not standardized are made of tool steel and heat treated according to drawing documentation.
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Rationalization of the production line
Straka, Jiří ; Štipčák, Jaroslav (referee) ; Osička, Karel (advisor)
This masters thesis optimises production of the step plates (which are parts of the sliding steps systems used in tramways, subways, hi-speed trains etc.) to increase the production rate to meet customers demand. The purpose of the work was reached by detailed analysis of the production process followed by evaluation of the results which led to the list of the possible solutions. The solution with the greatest time improvement was chosen and explained in detail.
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Evaluation of porosity in Al-alloy die-castings
Straka, Jakub ; Nová, Iva (referee) ; Čech, Jaroslav (advisor)
The purpose of this diploma thesis is an evaluation of die-castings porosity, eventually the evaluation of seats with local squeeze in connection with their mechanical and structural properties. The swatches of alloy AISi9Cu3 were taken from the engine block made by Škoda Auto Company, Mladá Boleslav. To the evaluation and the comparison of the results there were used value of porosity with own measure and other student´s thesis of Brno University of technology. Sets of mechanical and structural properties were selected, evaluated and tested by statistical programs.
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Sheets bonding and their testing
Straka, Jan ; Kandus, Bohumil (referee) ; Dvořák, Milan (advisor)
The aim of this bachelor thesis is to design selected load tests for bonded joints at specified steel sheet DC01 under laboratory conditions and to compare the strength of the degreased joints with technical alcohol and uncrushed joints. The basic methods of joining thin sheets are presented in the thesis. The following is an overview of test methods for bonded sheets according to the relevant technical standards. The results of the selected tests are the specific numerical values that have been compared with those reported by the manufacturer of the particular adhesive.
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Rationalization of assembly tools
Straka, Jiří ; Ondra, Josef (referee) ; Osička, Karel (advisor)
This bachelors thesis optimises arrangement of assembly tools in workplaces of the production line by using lean manufacturing methods. The purpose of the thesis was reached by waste analysis and implementation of the 5S method. Rationalization improved ergonomics of workplaces and saved more than 250 hours per year. In summary, it means undoubtedly good improvement in both productivity and costs reduction. Next steps will focus on purchasing of professional cordless automatic screwdrivers.
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