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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.
681

Geotermální energie - vliv geometrie vrtu / Geothermal energy - influence of the borehole geometry

Leiter, Augustin Unknown Date (has links)
Geothermal energy is one of the oldest forms of energy on our planet. Its use by humanity dates back to the beginning of the ages. The forms of this energy gradually changed from the direct heat of the hot springs, through the heating of the buildings and the baths to the later use of superheated steam for industrial use. Nowadays, there is a large share of the use of large number of ground geothermal boreholes with heat exchangers drilled in the matrix. The geometric arrangement of such system has a considerable impact on its operation. Specific examples show that, unlike the design, actual boreholes in such system can often be drilled non vertically or even curved. These imperfections then usually deteriorate the thermal properties of the system. This thesis demonstrates the influence analysis of the borehole geometry distortion on the system thermal properties, it also informs about the development of a special measuring device designed to obtain information about the actual geometric shape of the investigated borehole and about the development of software for in situ rapid borehole system properties evaluation. The theoretical part of thesis contains the derivation of a simplified numerical model of heat conduction in the vicinity of the borehole system. Its results serve to compare the different borehole variants and the inaccuracy of borehole shaping. Using the simulations, the influence of inaccuracies in the borehole system on its thermal properties is demonstrated in several model configurations. This effect does not occur in a single borehole, but it is significantly visible in organized geothermal borehole systems. It may deteriorate system properties, but under certain circumstances its properties may improve. Verification of the results of these simulations was performed by the FEFLOW simulation software. In the practical part the development of a special instrument for measuring the shape of a geothermal energy borehole is documented. ....
682

Techniky slučování kanálů za účelem zvýšení dynamického rozsahu kanálu s rozsahem ±10 V / Channel Merging Techniques for improving Dynamic Range of ± 10 V Signal Chain Channel

Dušek, Samuel January 2020 (has links)
Cílem této diplomové práce je změřit a vyhodnotit parametry techniky slučování kanálů, která je momentálně implementována v součástce AD7606C firmy Analog Devices. Poté, na základě výsledků z měření, navrhnout a odsimulovat několik možností, pomocí kterých by tato technika mohla dosahovat vyšších hodnot dynamického rozsahu a celkového harmonického zkreslení. V průběhů práce bylo zjištěno, že pomocí zvýšení zesílení kanálu s nižším rozsahem společně se snížením mezní frekvence celého signálového řetězce může tato technika dosahovat až 118.6 dB dynamického rozsahu, což je o 3.6 dB více, než bylo změřeno na AD7606C. Dále také bylo zjištěno, že pomocí jednoduchého algoritmu implementovaného v logickém bloku, je možné dosáhnout imunity vůči hodnotě externího rezistoru, který zákazníci používají jako součást anti-aliasingového filtru.
683

Měření nelineárních vlastností reproduktorů / Measurement of Non-Linear Properties of Loudspeakers

Friml, Vilém January 2020 (has links)
This thesis deals with calculation of THD dependency on signal frequency and calculation of Rub & buzz distortion using MATLAB software. Thesis includes generation of signals suited for THD measurement, playback and recording using sound card and APx series 500 device. The APx device controlling and data acquisition by MATLAB is also addressed. Loudspeaker electric model is discussed for the use of Rub & buzz measurement.
684

Měření zkreslení signálu EKG / ECG Signal Distortion Measures

Požár, Pavel January 2012 (has links)
This master's thesis deals with electrocardiogram and its distortion, which causes errors, due to which a doctor can make a wrong diagnosis. In the theoretical part electrocardiogram is briefly described, further theory of wavelet transform, introduction to the signal compression and some information about ECG delineation. Methods used for the signal evaluation and therefore determination of the distortion size are described in the main theoretical part. This thesis contains known methods and also a method of own design based on the ECG delineation. Some of the described methods are checked in the practical part. These methods are tested for two different compression algorithms, which cause various distortion. In the final part distortion was tested on the influence on setting the wrong diagnosis.
685

Elektrostatické vychylovací a korekční systémy / Electrostatic Deflection and Correction Systems

Badin, Viktor January 2015 (has links)
The aim of this master's thesis is to explore and study dynamic aberration correction options in electron-beam lithography systems. For the calculations, the thesis uses the optical column of the BS600 electron-beam writer. The thesis focuses on corrections of the third order field curvature, astigmatism, and distortion aberrations of the currently used magnetic deflection system and a newly designed electrostatic deflection system. The parameters of the two deflection and correction systems were compared.
686

Korekce snímků / Picture correction

Sedlo, Petr January 2016 (has links)
This work is focussed on different unwanted effects that damage a digitally acquired image. An image acquired using a digital camera can suffer from a series of defects. First, the noise is concerned. It occures due to discretisation. Next, there are the defects including vignetting, radial image distortion, chromatic aberration. In my thesis I also worked on backlight image compensation and panorama creation from an image sequence. For backlight images we need to increase the brightness in the dark parts of the image, so that the details became more visible. At panorama creation we are careful about brightness evenness in partial images, which is usually not conserved and consequently we try to find a suitable boundary-line to connect images and smooth it. The fundamental part of my work was writing the algorithms that are able to compensate these defects at least partly. For this aim I took use of the Matlab environment.
687

Studium chování betonů při působení vysokých teplot / Studying the behavior of concrete at high temperatures

Čonka, Ladislav January 2017 (has links)
The thesis is focused on the current issues of concrete resistance to high temperatures. The theoretical part has been processed the changes taking place in the individual components of concrete and changes affecting the physical - mechanical properties of concrete and color-changing effects manifesting high. In the experimental part of the load was, carried concrete test samples to a temperature of 400 ° C, 600 ° C and 800 ° C. After the thermal load, has been on test samples tested changes in physico - mechanical properties, especially concrete compressive strength, water absorption but also a visual assessment of the concrete surface
688

Linearizing E- Class Power Amplifier by Using Memoryless Pre-Distortion

Tunir Dey (5931197) 16 January 2020 (has links)
<div>Radio Frequency Power Amplifiers (PA) are essential components of wireless systems and nonlinear in a permanent way. So, high efficiency and linearity at a time are imperative for power amplifiers. However, it is hard to obtain because high efficiency Power Amplifiers are nonlinear and linear Power Amplifiers have poor efficiency. To meet both linearity and efficiency, the linearization techniques such as Digital Predistortion (DPD) has arrested the most attention in industrial and academic sectors due to provide a compromising data between efficiency and linearity. This thesis proposed on digital predistortion techniques to control nonlinear distortion in radio frequency transmitters. </div><div>By using predistortion technique, both linearity and efficiency can obtain. In this thesis a new generic Saleh model for use in memoryless nonlinear power amplifier (PA) behavioral modelling is used. The results are obtained by simulations through MATLAB and experiments. We explore the baseband 13.56 MHz Power Amplifier input and output relationships and reveal that they apparent differently when the Power Amplifier shows long-term, short-term or memory less effects. We derive a SIMULINK based static DPD design depend on a memory polynomial. A polynomial improves both the non-linearity and memory effects in the Power Amplifier. As PA characteristics differs from time to time and operating conditions, we developed a model to calculate the effectiveness of DPD. We extended our static DPD design model into an adaptive DPD test bench using Indirect Learning Architecture (ILA) to implement adaptive DPD which composed of DPD subsystem and DPD coefficient calculation. By this technique, the output of PA achieves linear, amplitude and phase distortions are eliminated, and spectral regrowth is prevented. </div><div>The advanced linearity performance executed through the strategies and methods evolved on this thesis can allow a higher usage of the capability overall performance of existing and emerging exceptionally performance PAs, and therefore an anticipated to have an effect in future wireless communication systems. </div>
689

Passage à l'échelle pour la visualisation interactive exploratoire de données : approches par abstraction et par déformation spatiale / Addressing scaling challenges in interactive exploratory visualization with abstraction and spatial distortion

Richer, Gaëlle 26 November 2019 (has links)
La visualisation interactive est un outil essentiel pour l'exploration, la compréhension et l'analyse de données. L'exploration interactive efficace de jeux de données grands ou complexes présente cependant deux difficultés fondamentales. La première est visuelle et concerne les limitations de la perception et cognition humaine, ainsi que celles des écrans. La seconde est computationnelle et concerne les limitations de capacité mémoire ou de traitement des machines standards. Dans cette thèse, nous nous intéressons aux techniques de passage à l'échelle relativement à ces deux difficultés, pour plusieurs contextes d'application.Pour le passage à l'échelle visuelle, nous présentons une approche versatile de mise en évidence de sous-ensembles d'éléments par déformation spatiale appliquée aux vues multiples et une représentation abstraite et multi-/échelle de coordonnées parallèles. Sur les vues multiples, la déformation spatiale vise à remédier à la diminution de l'efficacité de la surbrillance lorsque les éléments graphiques sont de taille réduite. Sur les coordonnées parallèles, l'abstraction multi-échelle consiste à simplifier la représentation tout en permettant d'accéder interactivement au détail des données, en les pré-agrégeant à plusieurs niveaux de détail.Pour le passage à l'échelle computationnelle, nous étudions des approches de pré-calcul et de calcul à la volée sur des infrastructures distribuées permettant l'exploration de jeux de données de plus d'un milliard d'éléments en temps interactif. Nous présentons un système pour l'exploration de données multi-dimensionnelles dont les interactions et l'abstraction respectent un budget en nombre d'éléments graphiques qui, en retour, fournit une borne théorique sur les latences d'interactions dues au transfert réseau entre client et serveur. Avec le même objectif, nous comparons des stratégies de réduction de données géométrique pour la reconstruction de cartes de densité d'ensembles de points. / Interactive visualization is helpful for exploring, understanding, and analyzing data. However, increasingly large and complex data challenges the efficiency of visualization systems, both visually and computationally. The visual challenge stems from human perceptual and cognitive limitations as well as screen space limitations while the computational challenge stems from the processing and memory limitations of standard computers.In this thesis, we present techniques addressing the two scalability issues for several interactive visualization applications.To address visual scalability requirements, we present a versatile spatial-distortion approach for linked emphasis on multiple views and an abstract and multi-scale representation based on parallel coordinates. Spatial distortion aims at alleviating the weakened emphasis effect of highlighting when applied to small-sized visual elements. Multiscale abstraction simplifies the representation while providing detail on demand by pre-aggregating data at several levels of detail.To address computational scalability requirements and scale data processing to billions of items in interactive times, we use pre-computation and real-time computation on a remote distributed infrastructure. We present a system for multi-/dimensional data exploration in which the interactions and abstract representation comply with a visual item budget and in return provides a guarantee on network-related interaction latencies. With the same goal, we compared several geometric reduction strategies for the reconstruction of density maps of large-scale point sets.
690

Eine phonetisch-phonologische Fehleranalyse von Monophthongen und Diphthongen zur Differenzierung der Sprechapraxie von der aphasisch-phonologischen Störung

Augustin, Juliane Irina Antje 11 May 2020 (has links)
Die vorliegende Studie untersucht die zugrunde liegende Frage, ob die Sprechapraxie und die aphasisch-phonologische Störung anhand phonetischer Entstellungen und phonematischer Paraphasien bei Diphthongen und Monophthongen voneinander unterschieden werden können. Ergänzend werden messphonetische Daten wie Vokal- und Wortdauern, der erste und zweite Vokalformant und die Voice Onset Time bei stimmlosen Plosiven im Silbenanlaut vergleichend herangezogen. Dazu werden drei Gruppen à vier Probanden untersucht: Gruppe SAX (mit Sprechapraxie), Gruppe APH (mit aphasisch-phonologischer Störung) und Gruppe NOM (sprachgesunde Kontrollgruppe). Es wird ein Nachsprechtest von 104 deutschen, meist monomorphematischen, einsilbigen Nomina, 52 einfache (CVC) und 52 komplexe (CCVC und CVCC) Silben, durchgeführt. Jeder Vokal wird durch acht meist unterschiedliche Wörter überprüft. Die Reaktionen werden mit dem phonetischen Analyseprogramm „Praat“ (Version 5.2.22, Boersma & Weenink, 1992–2011) segmentiert sowie ohren- und messphonetisch analysiert. Die statistische Auswertung erfolgt mit R (R Foundation) und R Studio (Version 0.98.1103, 2009–2014). Die Ergebnisse liefern Hinweise auf störungsspezifische Fehler bzw. Pathomechanismen der Sprechapraxie. Die Gruppe SAX produziert signifikant mehr phonetische Entstellungen bei Monophthongen und Diphthongen sowie signifikant längere Wortdauern als die Gruppe APH. In der Gruppe SAX sind einige Vokale nur teilweise entstellt, wie z. B. initial atypisch behauchte oder gerundete Vokale. Auch zeigen sich die Formantwerte in der Gruppe SAX variabler als in der Gruppe APH und der Gruppe NOM. Die Ergebnisse verweisen auf ein angenommenes Timing-Defizit bei der Planung und Kontrolle sprechmotorischer Bewegungen der Sprechapraxie. / This study analyses the underlying question if it is possible to distinguish apraxia of speech (SAX) and phonemic aphasia (APH) by phonetic distortions and phonological paraphasia of monophthongs and diphthongs. Phonetic measurements like the duration of vowels and words, the Voice Onset Time of voiceless plosives in the onset of syllables and the first and second formant will be analyzed as well. Three groups of four subjects are studied: Group SAX (no/mild aphasia), group APH (without apraxia of speech), group NOM (without any speech disorder). A repetition task comprising 104 German mostly monomorphemic, monosyllabic nouns, 52 simple (CVC) and 52 complex (CCVC and CVCC) syllables, is performed. Each of the vowels is tested in eight mostly different words. The reactions will be segmented, phonetically measured, and analyzed by ear with the help of the program “Praat” (Version 5.2.22, Boersma & Weenink, 1992–2011). The statistical analysis is conducted with R (The R Foundation), within the “R-Studio” software suite (Version 0.98.1103, 2009–2014). The results show some indications of failures and pathological mechanisms of apraxia of speech. Group SAX produces significantly more phonetic distorted monophthongs and diphthongs and significantly longer word durations than group APH. Some vowels are just partly distorted, for example, in form of atypical initial aspirated or rounded monophthongs. Also the formants show greater variability in group SAX than in groups APH and NOM. The results suggest a timing deficit during planning and control of speech movements in apraxia of speech.

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