National Repository of Grey Literature 87 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Chemical and Physical Properties of Impact Glasses
Křížová, Šárka ; Skála, Roman (advisor) ; Kohout, Tomáš (referee) ; Macháček, Jan (referee)
Abstract This work deals with microstructural features, chemistry and the search for traces of a meteoritic component in proximal tektite-like glasses from the Zhamanshin impact structure (Kazakhstan; further abbreviated as ZIS), and tektites from two strewn fields - moldavites (Czech Republic) and Australasian tektites (Laos; further abbreviated as AAT). Detailed microstructural observations and subsequent chemical and mineralogical studies of various types of inclusions were also performed; these inclusions were mostly found in the studied types of glasses for the first time ever. The aim of this PhD thesis was to (i) describe the microstructure of all studied glasses with a focus on yet unobserved microstructural phenomena, and (ii) try to determine the admixtures of meteoritic components in these glasses. In addition, the available target rocks, which could be a source of moldavites or AAT, were also studied. The microstructures of the studied glasses mutually differ. This is due to a diversity of parent materials and different glass formation conditions occurring during a particular impact event. A new type of "composite splash-form" has been identified among the ZIS glasses, whose chemical composition does not fit into the previously defined groups of irghizites or basic "splash-forms". For...
Bezpečnost práce v lesnictví
Macháček, Jan
Lesnictví je odvětví, které se z hlediska rizikovosti práce trvale řadí na jedno z předních míst žebříčků. Důvodem je skutečnost, že většina prací v lesním hospodářství probíhá téměř po celý rok ve vnějším prostředí za měnících se klimatických podmínek a také podmínek daného pracoviště. Dále tyto práce do jisté míry ovlivňují i na ně navazující pracovní činnosti. Práce v lese je velmi fyzicky namáhavá, vyžaduje zdravotní a fyziologické předpoklady a také značnou předvídavost. Ve všech ohledech se tedy jedná o práci velmi rizikovou. Například těžební činnost představuje v celosvětovém měřítku nejrizikovější aktivitu lesního hospodářství s nejvyšším podílem smrtelných úrazů. Častá jsou rovněž i onemocnění související s výkonem práce nebo vzniklá kontaktem s živými organizmy.
Technical and economic concept of a new pumped-storage power plant on the Smědá River
Vávra, Robert ; Macháček, Jan (referee) ; Radil, Lukáš (advisor)
The objective of this thesis is creation of technical and economic assessment of the suitability of pumped storage hydroelectric power plant Smědavský vrch. Thesis contain's technological design, power output and whole economic solution of the project with regard to construction and business.
Focus techniques of optical measurement of 3D features
Macháček, Jan ; Honec, Peter (referee) ; Janáková, Ilona (advisor)
This thesis deals with optical distance measurement and 3D scene measurement using focusing techniques with focus on confocal microscopy, depth from focus and depth from defocus. Theoretical part of the thesis is about different approaches to depth map generation and also about micro image defocusing technique for measuring refractive index of transparent materials. Then the camera calibration for focused techniques is described. In the next part of the thesis is described experimentally verification of depth from focus and depth from defocus techniques. For the first technique are shown results of depth map generation and for the second technique is shown comparison between measured distance values and real distance values. Finally, the discussed techniques are compared and evaluated.
Comparison of physical demands of fifteens and sevens rugby
Macháček, Jan ; Kaplan, Aleš (advisor) ; Hojka, Vladimír (referee)
Thema works: Comparison of physical demands of fifteens and sevens rugby Student: Jan Macháček Supervisor: Aleš Kaplan Aims: Outline the differences between rugby 7s and XVs based on a literature search. An analysis of the literature to find the terms that define the issue. Methodology: The method of literary research was used in the work, mainly from foreign sources. To meet the goal, concepts were chosen that helped to compile the idea of the structure of sports performance in rugby sevens and fifteens. Results: Over 250 electronic sources were acquired and researched as part of the fulfillment of the objectives of this work, based on the definitions of search keywords. All these sources were, with exceptions, in the English language. Of these, 60 articles covered men's sevens, 14 women's 7s, 68 men's and 7 women's XV, 32 youth rugby. Further 66 sources consisted of statistical yearbooks, periodization, talent identification articles, and coaching manuals. Three studies were identified, using a research method to compare aspects of different versions of rugby, but not in a systematic comprehensive form nor with the inclusion of both genders. Results of the research showed clear differences in per-minute running distances, higher frequency and length of sprints and high-intensity runs in the...
Conceptual development of the local distribution system Prototypa, a.s.
Vrtal, Matěj ; Macháček, Jan (referee) ; Radil, Lukáš (advisor)
This thesis is focused on the opportunities of conceptual development of the local distribution system Prototypa, a.s. At first, there is descripted condition of the current substations and internal electricity distribution system. Practical part of the thesis is dedicated to the evaluation of the construction of new transformer station and projection proposals of connection of the high-power charging station and new electric power supply.
BLDC motor control under load
Macháček, Jan ; Otava, Lukáš (referee) ; Pohl, Lukáš (advisor)
The bachelor thesis is focused on sensor control of BLDC motors by FOC (Field Oriented Control) method. In the first part of the thesis is the BLDC motor powered by ESC (electronic speed controller) by ST Microelectronics. In the second part is used own maked ESC. Both ESCs encompasses STM32F303 microcontroller specially fitted for BLDC motor control. In this thesis is used BLDC motor with twenty-two poles with inbuild magnetic rotary encoder. In the next part is described testbed for motor reaction torque testing during breaking in realation to connected load and load charakteristice is measured and listed. Reaction torque of motor is measured by sensor of mechanical stress. Furthermore is described function of active supply bus limiter.
Renewable Energy Auction Schemes
Jörka, Lukáš ; Macháček, Jan (referee) ; Radil, Lukáš (advisor)
The bachelor thesis deals with the current trend in the field of support for renewable energy sources – the transition from fixed payments to auction mechanisms. Firstly, the thesis describes principles of auctions in the field of RES support and capacity mechanisms. Subsequently, there are described advantages and disadvantages of auctions for RES support and defined their basic elements. This thesis deals with the current state of the global RES market and the description of the current state of the auctions implementation in Europe with focus on the auctions held in Germany and the United Kingdom. Furthermore, the thesis deals with the current state of the RES market in the Czech Republic describing the development of RES support in the past, the current situation and expected future development. The last chapter is devoted to the fictional economic model of wind park, for which the economic evaluation by the NPV method is performed for different values of the input parameters.
Power system model with the hydrogen storage
Vávra, Robert ; Macháček, Jan (referee) ; Radil, Lukáš (advisor)
The objective of this thesis is creation of power system model with hydrogen storage in open source program Open Modelica. Thesis contain’s whole design of each part of the system, power source, electrolyser, tank, block of methanation and theoretical basis for they creation.
The use of advanced composite materials for the design of concrete structures
Macháček, Jan ; Matušíková, Anna (referee) ; Girgle, František (advisor)
The diploma thesis deals with the design of concrete structures reinforced by FRP according to ACI, fib, CSA and EC2 regulations, which are stressed by a shear force. The diferences between steel rebar and FRP reinforcement were described, in particular its mechanical degradation over time and a different stress-strain diagram. Furthermore, shear capacity calculations were performed according to the regulations and compared with the real tests. Then the parametric analysis of shear strength was performed. In the practical part, the design of concrete floor slab structure supported by the pillars and walls was performed. The upper reinforcement of this slab was designed with FRP and the lower with steel rebar. Double-headed studs were used as a punching shear reinforcement.

National Repository of Grey Literature : 87 records found   1 - 10nextend  jump to record:
See also: similar author names
19 MACHÁČEK, Jan
1 MACHÁČEK, Josef
9 Macháček, Jakub
5 Macháček, Jaroslav
14 Macháček, Jiří
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