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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.
181

Rozvoj a využití nedestruktivních zkušebních metod z hlediska soudního inženýrství / Development and use of non-destructive testing methods from the point of view of forensic engineering

Bílek, Petr January 2019 (has links)
Concretes reinforced by, using distributed steel reinforcements (fibres) are known as fibre-concrete. In case of disturbances or accidents of concrete structures reinforced with wires, it is necessary to carefully examine the actual implementation of dispersed reinforcement. Fibre concretes belong to modern building materials whose possible applications have not been fully utilized so far. Have been mainly used for floor structures loaded with factory halls and warehouses. Recently, thanks to well-known physical and mechanical properties of fibre-concrete, there were numerous attempts of designers, and namely investors, to utilize this kind of materials for support structures either. Favorable properties of wire-concrete can be utilized if there is a necessity to increase the resistance of concrete to stresses exceeding its strength, cyclic stress or impact stress. Daily practice shows to prove that the applications of fibre-concrete in such structures lead to the economic success. Necessary condition for successful application of steel fiber reinforced concrete in constructions however consists in its uniform dispersion, a homogeneous distribution of the wires throughout the volume of the structure. In case of inappropriate processing and deposition of the mixture during the manufacturing process fiber-concrete structures, the fibers are often unevenly distributed. Wires itself represent unfavourably shaped mixture components and they are extremely deteriorating its workability. A grouping of wires may be encountered as well, which reduces the overall homogeneity and the quality of steel fiber-concrete structures. If the homogeneity of fibre-concrete is not kept, the material possess different properties in various parts of the structure (for example, tensile strength), which can lead to defects in the structure (generation and development of cracks). The relevant lower reliability of the structure which is caused by unequal distribution of fibres (wires) in concrete volume can lead to damage of the property as well as the safety and the human lives can be jeopardized. Hence it is necessary to secure the effective control of the fibre-concrete homogeneity in ready support fibre-concrete structures. Contemporary homogeneity control is still ongoing on fresh blends, but if the fibre-concrete hardened and is a part of the construction, no known reliable methods are currently in available to test the homogeneity of the fibre-concrete on the structure without its destruction. The methods developed to control the concentration of wires in wire-concrete structures are based mostly on magnetic or electromagnetic properties of wires. The thesis deals with the development of the magnetic method in situ using permanent magnets for monitoring the distribution of fibers in hardened steel fiber-concrete structures. The test principle is based on measurements of the changes in magnetic field strength of permanent magnets which are induced by a change in wire distribution in steel fibre-concrete structure. Test is characterized as a so called local- failure- test using a small diameter core drill. In this sense it is a semi-destructive method.
182

Akumulátorová sekačka na trávu / Battery supplied lawn mower

Picmaus, Jan January 2021 (has links)
The thesis deals with a concept of turning a conventional petrol powered lawn mower to a battery powered solution which is powered by lithium cells. A division to three chapters, comparison, mechanical and electrical, provides fluency of the whole design and further realization. The arrangement of chapters is performed so that the continuity of the thesis is maintained. Calculations of parameters of every motor and transmission with choosing particular devices are just a part of much interesting information which can be found in this thesis. All new components have full documentation except those which were changed during manufacturing. The electrical part explains every part of the schematics in detail. The realization contains difference between preliminary design and further production, manufacturing of the PCB and powering up the motor drives. The last part of the thesis contains temperature measurements of the device at no load.
183

Návrh automatického cyklu pro posuzování způsobilosti měření obrobkovou sondou na obráběcím centru / Design of an automatic cycle for assessing the measurement capability of a workpiece probe on a machining center

Mišún, Filip January 2021 (has links)
This diploma thesis describes the procedures of individual electronic compensations for CNC machines used to increase the accuracy of machines. This part is followed by the determining tolerance of the measuring and the influence of individual electronic compensations based on measured data using touch probe and calibrated standards according to VDA 5 norm.
184

Platforma pro měření atmosférických veličin / Platform for Measurement of Atmospheric Quantities

Hanák, Jiří January 2021 (has links)
This work is dealing with the design and implementation of an embedded system for aerology measuring. The aim of the system is to monitor atmospheric states during an ascent in the suspension under an meteorological balloon.   First of all, attention is given to the Earth's atmosphere and its quantities, then an overview of existing systems for performing aerological measurements. The core of the work is focused on the choice of measurement techniques and the selection of suitable measuring elements for a given scenario. The aerological probe is using atmospheric sensors HIH-8131-021-001, MS5611-01BA03 and PT1000-550 for temperature sensing, while GNSS data is received using the MAX-M8Q-0 module and the measured data is stored on a microSD card and transmitted in parallel using the MTX2-434.650-10 radio module. The system is controlled by STM32L1 from STMicroelectronics programmed in C using  HAL abstraction layer.
185

Vývoj bezdrátové bachorové sondy / Development of wireless rumen probe

Šídlová, Ludmila January 2011 (has links)
The aim was to study the possibilities of wireless transmission from the stomach of ruminants and to design and implement wireless ruminal probe. The first part deals with the internal wireless probe. The next section describes and evaluates available ruminal probe. There is given its own equipment design in the other chapters. The probe was designed for power management and for working with harvestable ambient power. The frequency of 125 kHz with bipolar coding was chosen for wireless data transmission. Two air coils are used on both sides as antennas. The proposed probe was designed and wireless data transmission was tested.
186

Rozložení proudu na lineárních anténách / Current distribution on linear antennas

Novák, Tomáš January 2011 (has links)
This work will describe current distribution measurement problems along antenna conductor using a probe (coupling loop), which is attached to selective micro-voltmeter, which will indicate signal level (voltage). The signal level will be used for representing the current distribution. Subsequently, measuring workplace issues from generator to antenna conductor, probe and selective micro-voltmeter, will be discussed. Analysis of voltages of this link-up and additional study will be conducted. Other parameters, which complement this situation, will be calculated from the current distribution. A computer program, which calculates these parameters and speeds up the collected data processing, will be used for this process.
187

Měření průtoku vzduchu pomocí víceotvorových rychlostních sond / Flow measurement of air by multiport averaging probes

Šimák, Jakub January 2011 (has links)
Master work deals with the measurement of fluid flow (particularly air) pipe, with orifice and multiport averaging probe. The theoretical part is followed by practical, which verifies the properties of the measured system. In a next part of semestral work are verifies the properties of multiport averaging probes Vavra s.r.o. MQS-011 and Rosemount Annubar 485. Measured values from probes are compared.
188

Měření výšky hladiny pomocí OVS / Measurement of Level by Fiber Optic Sensors

Bednář, Tomáš January 2011 (has links)
The subject of this master‘s thesis is the issue of design of fiber optic sensor for min/max and continuous measurement of liquid level, which could be used for laboratory measurement of optoelectronics. The thesis is divided into the three parts, the first part deals with methods of retrieval level measurement using fiber optic sensors. The second part is made of plant design of optical fiber sensors, it is shown the implementation of measuring devices for liquid level measurement and measured transfer characteristics of the sensors developed. The last part is proposed for laboratory typing tasks using established preparation for teaching in the subject Optoelectronic sensors.
189

Kompaktní měnič pro BLDC motor / Compact inverter for BLDC motor

Nevřivý, Tomáš January 2013 (has links)
The work describes the design and implementation of compact inverter for brushless DC motor, which have mechanical power 600 W and rated torque 1.6 Nm. Motor is designed for DC link voltage with value 300 V. The focus is placed on the cost and simplicity. On this basis, the inverter is designed for uses single purpose power and control circuit. The power part is solved using a circuit FSBB15CH60C. The circuit is placed on a separate board of power electronics. Cooling of the power circuit is performed by the surface structure of BLDC motor. Control of the inverter ensures circuits LB11696V and NE566. The both circuits are placed on separate board of control electronics. Circuit LB11696V contains a control algorithm, as well as protections, which are necessary for safe operation of the inverter. Power supply of electronics is performed using step-down converter from MYRRA company.
190

Vliv turbulentního modelu na simulace proudění vzduchu v okolí průtokoměru / Effect of the turbulence model for simulation of air flow around flowmeter

Vlček, Josef January 2014 (has links)
Purpose of this thesis is to check influence of turbulent model used for simulation of flow close to primary elementi inserted into piping. The goal is to check if results computed by these models are equal and how precise is their prediction.

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