National Repository of Grey Literature 25 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Kibble balance
Tomanec, Jakub ; Kunz, Jan (referee) ; Beneš, Petr (advisor)
The bachelor thesis consists of three sections. The first section explains the revision of the international system of units (SI), which took place in 2018 at the 26th General Conference on Weights and Measures (CGPM). The second section explains the concept of Kibble balance and introduces some of the created projects. In the third section of the work, the prototype of Kibble balance was realized. The fourth section contains the measurements of the prototype’s properties of the and the evaluation of the measured data. In the last section, possible sources of uncertainty and their possible solutions were evaluated.
Comparison of integrated circuits for management of single cell Li-ion battery
Novák, Štěpán ; Burian, František (referee) ; Kunz, Jan (advisor)
Lithium-ion batteries are now widely used as power sources for mobile devices, electric vehicles, consumer electronics and other applications. For proper operation and extended service life of Li-ion batteries, it is important that the parameters specified by the manufacturer are met. This is ensured by means of appropriate circuits, the accuracy of which is the focus of this paper. This work provides an overview and comparison of different types of circuits for Li-ion battery management and charging and explains the basic principles of their operation.
Visualization unit for pressure sensors
Pasch, Boris ; Kunz, Jan (referee) ; Čala, Martin (advisor)
This bachelor thesis has a goal of designing and implementing displaying unit for TPMS sensors which are usually used for checking tire pressure in passenger cars. This unit can receive data from sensors, display them and send them to a web page for remote viewing. Unit will be used for monitoring pressure in pneumatic expanding shafts on rewinding and cutting machines.
Programmable resistance decade
Rusnák, František ; Havránek, Zdeněk (referee) ; Kunz, Jan (advisor)
Goal of this work is design of programmable resistance decade controlled by microprocessor from the family STM32. The resistance decade will be used for testing energy harvesters. The theoretical parts deals with market research of commonly available resistor decades. The first designs of resistance decade were created. The principles of working can be multiple. The standard principle of working resistance decade is based on resistor rows switched by relays. The work also deals with solutions where is complex resistor rows replaced by electronics active components. In the practical part of this thesis, active design was designed builded and measured for all its range. Resistor decade can generate resistance from 100 Ohms to 10 mega-Ohms. Protocol SCPI allows to use this device in automated measurement.
Optical granulometry
Dohnálek, Martin ; Richter, Miloslav (referee) ; Kunz, Jan (advisor)
This diploma thesis deals with the topic of macroscopic particle size detection during freefall using computer vision. The measurement results can be used to verify other granulometric methods, or in the industry as a simpler alternative to conventional methods. Particle sampling takes place in flight and particles may overlap. Because of this, the data is recorded by a high-speed camera on the scene with fit-to-purpose lighting. The components of the proposed algorithm are: background removal, localization of potential particles, segmentation using the watershed method, determination of particle size. Using image correlation, the fall velocity and the number of particles in the sample are also determined. Experiments confirmed that the measured particle sizes of the sample correspond to the sizes determined by the traditional sieving method and are consistent even on repeated measurements. The correctness of the speed determination was verified by a theoretical calculation. When determining the effect of the sample’s dustiness on the quality of detection, resistance to the presence of dust up to 10% of the sample weight was found.
Measuring the Parameters of Piezo Energy Harvesters
Kunz, Jan ; Novák,, Martin (referee) ; Hadaš, Zdeněk (referee) ; Beneš, Petr (advisor)
This dissertation deals with the measurement of piezoenergy harvester parameters, in particular the measurement of their efficiency. The first part of the thesis summarizes important metrics for their comparison and reviews existing measurement systems for measuring harvester performance parameters. The measurement of harvester efficiency is simplified due to the complexity of power measurement and harvester efficiency is calculated from its parameters. However, this method is not accurate because it neglects mechanical losses and has a large measurement uncertainty. For this reason, the main objective of this work is to find a way to directly measure the harvester power input and thus measure its efficiency by definition, i.e. including mechanical losses. By analyzing the power flow in the harvester power chain, a way to achieve this goal has been found. Then, I have created an automated measurement system that allows to measure the harvester power parameters and also its efficiency including the determination of measurement uncertainties. In the last section, the performance, parameters and especially the two types of efficiency for commercially available harvesters are compared. As expected, the efficiency evaluated according to the definition come out smaller than in the case of its simplified version. However, this ratio varies widely for different harvester types, with the new efficiency being approximately one-third for PZT harvesters but only one-hundredth for PVDF harvesters. This significant difference shows that the different types of harvesters have large differences in mechanical losses, this difference could not be measured until now and thus remained neglected.
Simulation tool for fixed-point arithmetic
Grézl, Vojtěch ; Kunz, Jan (referee) ; Čala, Martin (advisor)
This bachelor's thesis is focused on creating tool for simulating calculations with fixed point. This tool simplifies and increases the efficiency of performing operations with values of different data types. By calculating and graphically displaying absolute errors, which creates a conversion of values between data types and conversion through maximum absolute errors, the user can evaluate whether this conversion is optimal or not. After getting acquainted with this issue in the theoretical introduction part, the design of the practical part follows, which summarizes the implementation and procedure of program design in the LabVIEW 2021. Process of draft of the practical part is based on attributes of LabVIEW and it’s part FPGA module and aim on creating of transparent and user-friendly user interface. The output of the practical part is a tool that works with the created VI, containing a sequence of different operations with different input and output data types. The program is used to convert numbers of different data types to another type, mainly for a conversion to a fixed point data type. The user gives the main direction by creating a sample VI, the operations of which will then be performed. Other parameters that the user can set and affect the program are listed on the user interface.
Kibble balance
Tomanec, Jakub ; Kunz, Jan (referee) ; Beneš, Petr (advisor)
The bachelor thesis consists of three sections. The first section explains the revision of the international system of units (SI), which took place in 2018 at the 26th General Conference on Weights and Measures (CGPM). The second section explains the concept of Kibble balance and introduces some of the created projects. The third section of the work was the creation of a prototype Kibble balance, evaluation of measured data and design of future modifications of the prototype.
Thermal Mass Flowmeter
Mlčoch, Albert ; Kunz, Jan (referee) ; Beneš, Petr (advisor)
The thesis deals with the design of a mathematical model and practical implementation of a flowmeter based on the thermal principle. The range of the proposed flowmeter is from units of kilograms per hour to lower hundreds of kilograms per hour. The design of the flowmeter is non-invasive to the flow channel, the heating element is located outside the pipe. In this paper, the flowmeter parameters are identified and a temperature regulator is proposed. Measurements are made on a test bench. The results of the measurements are discussed. Modifications to the existing hardware are suggested.
Fir Filter Resonance Compensation For Random Vibration Generation
Kunz, Jan
This paper deals with a random vibration generation on vibration shakers using a FIR filter. Every shaker has its resonances and anti-resonances which causes troubles in random vibration generation, for instance in presented shaker the difference between maximum and minimum in frequency characteristic is nearly 50 dB. Therefore, we decided to create a FIR filter with inverse characteristic with respect to the shaker to minimize those differences. To design such a filter a freqeuncy characteristic of the shaker has to be measured, then the characteristic is simplified using Ramer–Douglas–Peucker algorithm. Finally, the characteristic is inverted and FIR filter is designed using Remez algorithm. Using this FIR filter the difference in frequency characteristic drops from 50 dB to less 2 dB.

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2 Kunz, Jiří
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