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Wave Soldering Fluxes and Flux Residues
Kryll, Josef ; Dušek, Karel (referee) ; Starý, Jiří (advisor)
This work deals with issues of flux residues after wave Soldering. The general aim is to create methodology for measuring the surface insulation resistance values of flux residues after soldering and isothermal heating. Finding the ammount of ionic contamination by using conductometric method. Measurement of wettability of Cu wire by using wetting balance method for different fluxes. The aim is then to compare the measured values with the values dictated by the manufacturer.
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PCBs Cleaning Process Optimization
Smejkal, Jakub ; Tichopádek, Petr (referee) ; Starý, Jiří (advisor)
The diploma thesis introduces readers to the issue of PCB cleanliness by a short analysis of historical approaches to their cleaning. The theoretical part defines what phenomena occur in case of leaving impurities on the PCB and names the different types of impurities with a focus on fluxes. It also deals with types of cleaning fluids and selected technologies suitable for PCB cleaning, including research of specific products and their manufacturers. The practical part analyses the current state of washing processes in the company TESCAN Brno, s.r.o and performs the initial cleanliness test of PCBs from external suppliers and internally assembled PCBs. Based on the performed analysis, the work then focuses on the replacement of the current cleaning fluid and the optimization of the used solder. In connection with the process and results of a series of test measurements performed in both monitored areas, work proposes a methodology for evaluating the current applicability of the cleaning liquid and for testing the surface insulation resistance.
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Music Source Separation
Holík, Viliam ; Veselý, Karel (referee) ; Mošner, Ladislav (advisor)
Neural networks are used for the problem of music source separation from recordings. One such network is Conv-TasNet. The aim of the work is to experiment with the already existing implementation of this network for the purpose of potential improvement. The models were trained on the MUSDB18 dataset. It was successively experimented with the change of the network structure, transforming signals from the time domain to the frequency domain for the purpose of calculating the loss function, replacing different loss functions with the original one, finding the optimal learning rate for each loss function and gradually decreasing the learning rate during the learning process. The best experiments according to the SDR metric were training with loss functions L1 and logarithmic L2 in the time domain with a higher initial learning rate with its gradual decrease during the learning process. In a relative comparison of the best models to the baseline, it is more than 2.5% improvement.
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Workforce Composition Effects on Covid-19 Spread: a SIR model and an Application to the Czech Regions
Škultéty, Oliver ; Gregor, Martin (advisor) ; Chytilová, Julie (referee)
One of the main types of government intervention aimed at fghting the COVID-19 pandemic were the social distancing measures. This thesis presents a novel approach to examining the relationship between social distancing and workforce composition. The model used is a SIRD model with dynamically optimizing individuals. The model is estimated for each Czech region and cali- brated for the 'social distancing measure' so that the model predictions best ft the data. This measure is then compared in a regression with the share of skilled labour in each region. This thesis fnds that a large degree of variance of social distancing between regions can be explained by the workforce composition. 1
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Dynamics of epidemics
Švamberová, Lucie ; Kaplický, Petr (advisor) ; Pražák, Dalibor (referee)
Spreading of infectious diseases in population is one of many phenomenons that can be described using differential equations. In this bachelor thesis, we deal with epidemiologic models SEIR, SIR respectively. First, we formulate models SEIR and SIR and then examine the properties of their solutions - existence, uniqueness, boundedness. We show that the solution of SEIR can be converted to the solution of SIR. After that we pursue dynamics of SIR model - we examine the stability and type of the stationary points with respect to values of the parameters.
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Wave Soldering Fluxes and Flux Residues
Kryll, Josef ; Dušek, Karel (referee) ; Starý, Jiří (advisor)
This work deals with issues of flux residues after wave Soldering. The general aim is to create methodology for measuring the surface insulation resistance values of flux residues after soldering and isothermal heating. Finding the ammount of ionic contamination by using conductometric method. Measurement of wettability of Cu wire by using wetting balance method for different fluxes. The aim is then to compare the measured values with the values dictated by the manufacturer.
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