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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.
351

Návrh systému měření teplot na zkušebně tepelných čerpadel / Concept of Temperature Measurement System on Heat Pump Test-room

Macháčková, Petra January 2011 (has links)
This work deals with design of temperature measurement on heat pump test-room. Discusses diferent various variants of thermometers and their placements in measurement circuit. It contains sample software for control and processing of measured data on the test-room, which is controlled by the computer and built-in data acquisition card.
352

Měření a analýza dynamických vlastností rotujících částí strojů / Measurement and analysis of dynamic properties of rotating machine parts

Gofroň, Vojtěch January 2015 (has links)
Diploma thesis focuses on measurement and analysis of shaft motion, torque, angular velocity and vibration. First part of the thesis deals with general issue of acquiring a digital signal. Next part describes suitable sensors for each measurement type, and data acquisition hardware. The last theoretical part describes methods for measurement data analysis and vibration diagnostics. Practical part of the thesis describes shaft motion and torque measurements made on laboratory equipment, and vibration measurement made on real machine system. Each measurement includes measurement data analysis and evaluation.
353

Aufbau und Charakterisierung einer Frisch-Gitterionisationskammer für die Spektroskopie niedrigster spezifischer Aktivitäten

Krüger, Felix 19 December 2013 (has links)
Im Rahmen dieser Arbeit wurde eine Frisch-Gitterionisationskammer zum Messen kleinster spezifischer Alphaaktivitäten realisiert. Im konkreten Fall soll der Detektor dafür genutzt werden, die Halbwertszeit von 144Nd erneut zu bestimmen. Da diese sehr lang (T1/2 = (2,29 ± 0,16) · 10^15 Jahre) und die Reichweite der emittierten Alphateilchen in Feststoffen sehr gering ist, können nur sehr dünne Proben untersucht werden. Die Fläche der Proben sollte sehr groß sein, um die nötige Aktivität zu erhalten. Im Vergleich haben sich Gitterionisationskammern als das geeignetste Detektorkonzept erwiesen. Es wurde eine Kammer realisiert, welche aus zwei Gitterionisationskammern mit geteilter Anode besteht. Mit Hilfe dieses Aufbaus ist es möglich den Detektornulleffekt zu reduzieren. Die Auslese der auf den Detektorelektroden induzierten Ladung erfolgt mit Hilfe eines Analog-Digital-Konverters. Die Auswertung der gewonnenen Daten wird vollständig nach der Messung durchgeführt. Anhand einer Pulsformanalyse können verschiedene Informationen über jedes, im Detektor stattgefundene, Ereignis gewonnen werden. So ist es möglich den Gitterdurchgriff und die damit verbundene Winkelabhängigkeit der Pulshöhen zu korrigieren und somit die Energieauflösung des Detektors zu verbessern. Es wird eine Energieauflösung von 0,86 % bei 5,1 MeV erreicht. Die Charakterisierung der Ereignisse wird außerdem für die Reduktion des Detektornulleffekts herangezogen. Aufgrund verschiedener Bedingungen, die für ein zu erwartendes Alphaereignis notwendig sind, kann ein Großteil der, die Messung störenden Ereignisse, unterdrückt werden. So kann der Nulleffekt im Energiebereich von 1 MeV bis 2,2 MeV von 435 Ereignissen pro Tag ohne Charakterisierung um etwa ein Faktor 20 auf 21,6 Ereignisse pro Tag mit Charakterisierung reduziert werden. Die Nachweiseffizienz wird davon nicht merklich beeinträchtigt. Für ausreichend lange Messzeiten ist eine Nachweisgrenze von weniger als 10 Ereignissen pro Tag zu erwarten. Für eine, für diesen Aufbau geeignete, Targetgeometrie ist mit etwa 50 Alphazerfällen des 144Nd pro Tag zu rechnen. Mit einer Nachweiseffizienz von etwas unter 50 % sollte die Messung am 144Nd gut möglich sein. / The realization of this work was the usage of a Frisch grid ionization chamber for measuring the lowest specific alpha activity. In the practical case the detector should be used to remeasure the half life of 144Nd. Only very thin targets can be used, due to the extreme long half life and the very short range of alpha particles in matter. The area of the samples must be big enough to get the required activity. In comparison gridded ionization chambers are the most practical devices. The chamber was realized in that way, that two gridded chambers shares a common anode. This could be used to minimize the detector background. The charge, which was induced in the detector electrodes, is acquired by an analog to digital converter. The full analysis of the data is done after the measurement. With the pulse form analysis it is possible to extract information about every event occurring in the detector. It is also possible to correct the grid inefficiency and the correlated angle dependence of the pulse height. This improves the energy resolution. A resolution of 0.86 % at 5.1 MeV is possible. The characterization of the events is also used for the suppression of the detector background. Due to different conditions for an assumed alpha event the majority of the events which disturbs the measurement could be removed. So it is possible to suppress the background in the range between 1 MeV to 2.2 MeV of 435 events per day without the characterization to 21.6 events per day with characterization, which is a factor of roughly 20. The detection efficiency is not noticeably effected. For sufficiently long measurements a lowest limit of detection of 10 counts per day is expectable. For a target geometry which can be used with this setup, about 50 alpha decays of 144Nd per day will occur. With a detection efficiency a bit below 50 % the measurement on Nd should be possible.
354

On the establishment of a data-driven approach to gravel road maintenance

Mbiyana, Keegan January 2023 (has links)
Gravel roads are essential for economic development as they facilitate the movement of people, transportation of goods and services, and promote cultural and social development. They typically connect sparsely populated rural areas to urban centres, providing essential access for residents and entrepreneurs. Maintaining these roads to an acceptable level of service is crucial for the efficient and safe transportation of goods and services. However, substantial maintenance investmentis required, yet resources are limited. Gravel roads are prone to dust, potholes, corrugations, rutting and loose gravel. They deteriorate faster than paved roads, and their failure development is affected by traffic action and physical, geometric and climatic factors. Thus, more condition monitoring and proper road condition assessment are necessary for dynamic maintenance planning to reach efficiency and effectiveness using objective, data-driven condition assessment methods to ensure all-year-round access. However, objective data-driven methods (DDMs) are not frequently used for gravel road condition assessment, and where they have been applied, the practical implementation is limited. Instead, visual windshield assessment and manual methods are predominant. Visual assessments are unreliable and susceptible to human judgement errors, while manual methods are time-consuming and labour-intensive. Maintenance activities are predetermined despite dynamic maintenance needs, and the planning is based on historical failure data rather than the actual road condition. This thesis establishes a data-driven approach to gravel road maintenance describing the systematic assessment of the gravel road condition and collection of the condition data to ensure efficient and effective maintenance planning. This thesis uses a design research methodology based on a literature review, concept development, interview study and field experiments. A holistic approach is proposed for data-driven maintenance of gravel roads encompassing objective condition data collection, processing, analysing, and interpreting the findings for obtaining reliable information concerning the condition to gravel road decision support by utilising the opportunities presented by technological advancements, particularly sensor technology. Then, decision-making is primarily influenced by the objectively collected gravel road condition data rather than the evaluator’s perception or experience. The successful implementation of a data-driven approach depends on the quality of the collected data; therefore, data relevance and quality are emphasised in this thesis. The lack of data quality and relevance hinders effective data utilisation, leading to less precisionin decision-making and ineffective decisions. Furthermore, the thesis proposes a participatory data-driven approach for unpaved road condition monitoring, allowing road users to be part of the maintenance process and providing an efficient and effective alternative for collecting road condition data and accomplishing broad coverage at minimum cost. A top-down iiapproach for data-driven gravel road condition classification is proposed to achieve an objective assessment to address the lack of readily available quality and relevant condition data. The established data-driven approach to gravel road maintenance is evaluated and verified with field experiments on three gravel roads in Växjö municipality, Southern Sweden. The research findings indicate that properly implementing a data-driven approach to gravel road maintenance would ensure efficient and effective condition assessment and classification, which are a basis for a maintenance management system of gravel roads and enable road maintainers and authorities to achieve cost-effective decision-making. / Sustainable maintenance of gravel road
355

Optimalizace rekonstrukce obrazu v elektrické impedanční tomografii / Optimizing Image Reconstruction in Electrical Impedance Tomography

Dušek, Jan January 2022 (has links)
Tato disertační práce pojednává o optimalizaci algoritmů pro rekonstrukci obrazu neznámé měrné vodivosti z měřených dat pořízených elektrickou impedanční tomografií. Danou problematiku zde věcně vymezuje několik různých prvků, zejména pak stručný matematický popis dopředné a inverzní úlohy řešené různými přístupy, metodika měření a pořizování dat pro rekonstrukci a přehled dostupných numerických nástrojů. Uvedenou charakteristiku rozšiřuje rozbor optimalizací parametrů modelu ovlivňujících přesnost rekonstrukce, způsoby paralelního zpracování algoritmů a souhrn dostupných zařízení pro měření tomografických dat. Na základě získaných poznatků byla navržena optimalizace parametrů matematického modelu, která umožňuje jeho velmi přesný návrh dle měřených dat. V této souvislosti dochází ke snížení nejistoty rekonstrukce rozložení konduktivity. Pro zefektivnění procesu získávání dat bylo navrženo zařízení k automatizaci tomografie s důrazem na cenovou dostupnost a snížení nejistoty měření. V oblasti tvorby numerického modelu byly dále zkoumány možnosti užití otevřených a uzavřených domén pro různé metody regularizace a hrubost sítě, a to s ohledem na velikost chyby rekonstruované konduktivity a výpočetní náročnost. Součástí práce je také paralelizace subalgoritmů rekonstrukce s využitím vícejádrové grafické karty. Předložené výsledky mají přímý vliv na snížení nejistoty rekonstrukce (optimalizací počáteční hodnoty konduktivity, rozmístění elektrod a tvarové deformace domény, regularizačních metod a typu domén) a urychlení výpočtů paralelizací algoritmů, přičemž výzkum byl podpořen vlastním návrhem jednotky pro automatizaci tomografie.
356

A Measurement of the Weak Charge of the Proton through Parity Violating Electron Scattering using the Qweak Apparatus: A 21% Result

Beminiwattha, Rakitha S. 24 September 2013 (has links)
No description available.
357

Design and implementation of a data acquisition system with filter quality evaluation / Design och implementering av ett datainsamlingssystem med filterkvalitet utvärdering

Karlsson, Örn Arnar January 2019 (has links)
Particulate matter is a growing health concern that is considered to contribute to many diseases. To develop appropriate air filtration systems, we need to understand how particulate matter affects air filters. In this project, we implement an automated data acquisition system for an air filter test rig. The data acquisition system allows us to gather empirical data on how particle matter affects air filters over time. Although the quality of the air filters does not reach critical levels, there is a measurable degradation. The collected data is used to train and validate a machine learning model that can evaluate air filter quality. This machine learning proved to be a powerful tool in air filter evaluation and performs with 99% accuracy on test data. The result of this project is a fully functioning data acquisition system along with a user interface that considerably reduces the number of man-hours needed to perform tests of filters. In addition, the automated data acquisition system can notify the operator when the rig needs a change of filter or when certain faults occur. Unfortunately, the project did not reach its original goal of being able to automatically determine when the test rig needs maintenance or re-calibration. / Luftburna partiklar är en växande hälsorisk som anses bidra till ohälsa. För att utveckla lämpliga luftfiltreringssystem måste en bättre förståelse nås för hur luftburna partiklar degraderar luftfilter. I det här projektet så implementeras ett automatiskt datainsamlingssystem i en testrigg för luftfilter. Datainsamlingssystemet samlar in empiriska data för hur luftburna partiklar degraderar filter över tid. Även om luftfiltren inte når kritiska nivåer, visar testerna på en mätbar degradering. Insamlat data används för att träna och validera en maskininlärningsmodell för att utvärdera filterkvalitet. Maskininlärning visade sig vara en kraftfull metod för att utvärdera luftfilter med 99% noggrannhet för testdata. Resultatet av det här projektet är ett fullt fungerande datainsamlingssystem tillsammans med ett användargränssnitt som avsevärt minskar tidsåtgången för att utföra test och utvärdera filter. Dessutom kan det automatiska datainsamlingssystemet meddela operatören när riggen behöver byta filter eller när vissa fel uppstår. Återstående arbete består i att implementera när testriggen behöver service eller kalibrering.
358

Zustandsüberwachung von Maschinen durch Datenabgriff an bestehender Sensorik und Nachrüstung einfacher Energiemesstechnik an Bestandsmaschinen

Grundmann, Andreas, Schmidt, Jens, Reuter, Thomas 28 November 2023 (has links)
Metall- und Maschinenbauunternehmen müssen im Durchschnitt pro Jahr ca. zwei Prozent ihres Umsatzes für Strom und Erdgas ausgeben und die Unternehmer gehen von weiteren Preissteigerungen aus. Damit rückt das Thema Energieeinsparung stärker denn je in den Fokus und wird zu einem strategischen Faktor. Um Kosten zu sparen und Wettbewerbsvorteile zu sichern, ist es notwendig, zielgenaue Energieeinsparmaßnahmen einzuleiten. Die ersten Maßnahmen, welche die meisten Maschinenbauunternehmen umsetzen, sind die Erneuerung der Beleuchtungs-, Heizungs- und Lüftungsanlage, die Verbesserung der Drucklufterzeugung sowie die thematische Sensibilisierung der Mitarbeiter. Aber auch in Maschinen mit ihren dazugehörigen elektrischen Antrieben, Lüftern und Aggregaten verbirgt sich eine große Menge an Optimierungspotenzial. Allerdings ist es hier notwendig nicht die Verbraucher im Einzelnen, sondern die Maschine und deren Prozesse im Ganzen zu betrachten. Meist fehlen hierfür aber geeignete Schnittstellen, um die Messwerte von Sensoren (bspw. Temperatur-, Drucksensoren, etc.) und Antrieben auslesen zu können, was dazu führt, dass diese Potenziale nicht ausgeschöpft werden.
359

Condition monitoring of machines by tapping data from existing sensors and retrofitting simple energy measurement technology to existing machines

Grundmann, Andreas, Schmidt, Jens, Reuter, Thomas 28 November 2023 (has links)
The average metal and mechanical engineering company must spend around two per cent of its annual turnover on electricity and natural gas, and companies are expecting further price increases. As a result, the issue of energy saving is becoming more of a strategic factor than ever before. In order to save costs and ensure competitive advantages, it is necessary to introduce precise energy-saving measures. The first steps taken by most mechanical engineering companies are to replace lighting, heating, and ventilation systems, improve compressed air generation and raise employee awareness. However, there is also a great potential for optimization in machines with their individual electrical drives, fans, and units. In this case, though, it is necessary to look at the machine and its processes as a whole rather than the individual electrical energy consumers. In most cases, however, there is a lack of suitable interfaces for analyzing the measured values from sensors (e.g. temperature, pressure sensors, etc.) and drives, which concludes that this potential is not fully exploited.
360

Supervisory Control Validation of a Fuel Cell Hybrid Bus Using Software-in-the-Loop and Hardware-in-the-Loop Techniques

Ramirez, Steven Abraham January 2013 (has links)
No description available.

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