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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Kalibrace nepřímých metod pro zjišťování vlastností alkalicky aktivovaných betonů / Calibration of indirect methods for maesurement of properties of alkali activated concretes

Vrba, Pavel January 2014 (has links)
This work solves creation of calibration relations to determine cube compressive strength, dynamic and static elastic modulus of alkali-activated concrete by non-destructive methods. Alkali-activated concrete is spoken of as a new material used in civil engineering. It shows different properties than normal concrete based on Portland cement. That's why the modification of common calibration relation seems necessary. Fresh concrete was made in the concrete plan ŽPSV a.s., Uherský Ostroh in three mixtures and always in the number of 18 cubes and 3 prisms. The samples were tested by impact hammer Schmidt type L, type N, SilverSchmidt PC-N and by ultrasound in 6 time periods of three specimens. After that, the cube compressive strength was determined. Status of static elastic modulus was determined in a time period of 28 days. The results are calibration relations to determine the progress of compressive strength and modulus of elasticity for each method and their combination.
112

Návrh letounu podle předpisu FAR 103 / Design of Aircraft in Accordance with FAR 103 Regulation

Tomala, Daniel January 2008 (has links)
This diploma work considers conceptual design of aircraft in accordance in FAR 103 regulation. On the base of statistical dates has been made basic geometrical and aero-dynamical concept of a single occupant aircraft. For conception have been chosen optimal driving force and bases calculations of the load pressure and dimensions are included.
113

Racionalizace výroby a kontroly vřeten vodárenských armatur / Redeployment and verification spindles water supply river armours

Jelínek, Norbert January 2009 (has links)
Solving problems of production and calibration spindles water supply river armours by the help of method SPC. Analysis capability of gauge by the help of methodists MSA-Cg,Cgk. Evaluation capability of machanical abnd digital outside micrometer. Verification limiting deviation of micrometrical screw in among - calibration interval. Attestation capability of machine and of the process. Construction of regulation diagram. Project of new control instruments. Technically-economic evaluation:savings 110 560,00Kč, profitability 764,85%, economic return 0,13 year. Successful application of methodists SPC attested by document about adjustability of the process.
114

Diagnostika PN přechodu křemíkových vysokonapěťových usměrňovacích diod pomocí šumu mikroplazmatu / Microplasma Noise as a Diagnostic Tool for PN Junctions of High-Voltage Rectifier Diodes

Raška, Michal January 2009 (has links)
The doctoral thesis deals with diagnostics of local defects in PN junctions and brings new information about microplasma noise behaviour and its usage for the temperature changes detection inside PN junctions. Defects in PN junctions are the source of microplasma noise. There were deviations observed in microplasma noise from the common known rectangle shape pulses during the measurements. These deviations were correlated with the temperature change directly in the defect area and in the defect area surroundings. Generation and recombination coefficients are commonly thought to be constant. However, these coefficients were observed to be not stable with time and this effect is explained in this work. The doctoral thesis then focuses on the PN junction parameters determination in the case when it is not possible to define unambiguously whether it is abrupt or linearly graded PN junction. The most significant parameters which are to be determined are barrier capacity, diffusion voltage and depleted area width in dependence on the voltage. The correlation between local avalanche discharge in PN junction and negative differential resistance appearance on VA characteristics of reverse-biased diode was qualitatively verified. The last important point in the work is computer modelling of temperature behaviour in the defect area and its surroundings during local avalanche breakdown. Thus the method of real diodes heating area parameters determination was introduced.
115

Vývoj metod in-line tepelného zpracování / Developement of In-Line Heat Treatment Methods

Hnízdil, Milan January 2012 (has links)
In-line heat treatment is a part of technological process uses a phase and structure changes to obtain required mechanical properties. Heat treatment of rolled products offers a reduction of steel making costs and a creation of new steel products. For example the TRIP steel is a part of modern steels which is used in the automobile industry for higher safety of passengers. The heat treatment is often described in the literature. But the authors are often focused on the method how to get the required structure and mechanical properties for different metallic materials. Nevertheless just few articles are focused on the technical observing of temperature regimes and which parameter is necessary to consider during designing the cooling section. Eight parameters were tested by the experimental way to examine their influence on the cooling intensity. They were: gravity (orientation of the cooled surface), coolant pressure, amount of coolant spraying on the surface (the flow rate), rolling velocity, nozzle configuration, kind of nozzles (full cone or flat fan nozzle), coolant temperature and the surface quality (surface roughness and scales). All these parameters have an influence the heat transfer coefficient. Based on knowledge gained in this work was created the cooling section, which comply with the required cooling temperature regimes.
116

Rozvoj inverzních úloh vedení tepla řešených s využitím optimalizačních postupů a vysokého stupně paralelizace / Development of inverse tasks solved by using the optimizing procedures and large number of parallel threads

Ondroušková, Jana Unknown Date (has links)
In metallurgy it is important to know a cooling efficiency of a product as well as cooling efficiency of working rolls to maximize the quality of the product and to achieve the long life of working rolls. It is possible to examine this cooling efficiency by heat transfer coefficients and surface temperatures. The surface temperature is hardly measured during the cooling. It is better to compute it together with heat transfer coefficient by inverse heat conduction problem. The computation is not easy and it uses estimated values which are verified by direct heat conduction problem. The time-consuming of this task can be several days or weeks, depends on the complexity of the model. Thus there are tendencies to shorten the computational time. This doctoral thesis considers the possible way of the computing time shortening of inverse heat conduction problem, which is the parallelization of this task and its transfer to a graphic card. It has greater computing power than the central processing unit (CPU). One computer can have more compute devices. That is why the computing time on different types of devices is compared in this thesis. Next this thesis deals with obtaining of surface temperatures for the computation by infrared line scanner and using of inverse heat conduction problem for the computing of the surface temperature and heat transfer coefficient during passing of a test sample under cooling section and cooling by high pressure nozzles.
117

Identifikace tepelné vodivosti a tepelné kapacity stavebních látek metodou „Hot Wire Method“ / Identification of Thermal Conductivity and Thermal Capacity of Building Materials by the "Hot Wire Method"

Průša, David January 2019 (has links)
This aim of task deals with study of heat dissipation mechanisms and the description of physical phenomena, which is accompanied by non-stationary measurement of thermal characteristics by the method "hot-wire method". In particular, we observe the coefficient of thermal conductivity and its dependence on various variables such as the temperature of the measured sample, its moisture state, the volume of the sample and its porosity. The above mentioned findings are used for the invention of the measuring device of a nonstationary gauge, which is based on regular heating and is dedicated to measuring the thermal conductivity coefficient and the heat capacity by the "hot-wire method" method. In the last part of the thesis is verified functionality of the proposed measuring device, the suitability of the created algorithm for the processing of the measured data and the evaluation of the results was verified. The reproducibility of the measurements was verified and the measured results were compared with the measurement methods, which are commonly used. the influence of humidity on the coefficient of thermal conductivity.
118

Tepelně technické posouzení novostavby rodinného domu

Kunert, Martin January 2014 (has links)
The thesis deals with the issue of thermal-technical assessment of new building of family house which is going to be built in the near future, based on provided documentation. Considering the building system, it is a wooden house, which is going to be realized through a "balloon frame" method. The goal of this thesis is to propose suitable composition of individual constructions, to asses them and to develop basic construction details of them which will be evaluated based on internal surface temperature and linear thermal transmission. Based on intermediate results the thermal loss of the family house will be calculated which is a crucial input for proposal of the heating system. Another part focuses on proposing of controlled ventilation system and creating energy performance certificates of the building.
119

Studium tepelně izolačních vlastností cementových betonů při zvýšené teplotě / Study of thermal insulation properties of cement concrete exposed to high temperature

Nováková, Iveta January 2014 (has links)
Master`s thesis is divided in to two parts, practical and theoretical. In theoretical part are listed basic information’s about light weight concrete, special emphasis are given to characteristic and practical application of compact light weight concrete with Liapor aggregates. In this study is described influence of high temperature on concrete structure and chemical, mechanical and physical changes, which take place during exposal to high temperatures. Further is evaluated surface permeability of concrete and addition of polypropylene fibres to concretes resistive to high temperatures. The practical part deals with design, production and testing of cement based concrete with use of different aggregates (light weight aggregates Liapor, basalt). The properties and use for applications in high temperatures is also mentioned. The influence of high temperature on strength, absorption, thermal conductivity, changes of surface permeability and degradation of testing specimens due to heat loads according to normative heat curve (ISO 834). For better transparency are experimental tests divided in to five phases and the measured values are evaluated on the end of each phase. In conclusion are resumed all knowledge’s obtained by testing and evaluated the most suitable formulation. The approach for further research is also mentioned.
120

Studium tepelných poměrů a vhodných materiálů pro konstrukci energetického zásobníku pro dlouhodobé ukládání energie v podmínkách klimatu ČR / Study of thermal conditions and the appropriate materials for construction of the energy reservoir for long term storage in the conditions of climate CR

Bukvová, Veronika January 2018 (has links)
Presented work deals with appropriate ways of storing thermal energy and selection of materials for a high capacity storage unit. The thesis describes technologies currently used for long-term storage of thermal energy, the structural arrangement of the thermal unit, physical properties of the materials usable for construction of high-temperature storage units and the utilization of these materials. The thesis also describes the measuring procedure of the material characteristics and the method of evaluation. Size of the solar collector and the required volume of the storage for heat supplying of the selected building in the climatic conditions of the Czech Republic were designed.

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