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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.
1

Measurement and Analysis of the Standby Power of Twenty-Seven Portable Electric Spas

Hamill, Andrew Ian 01 September 2012 (has links) (PDF)
Portable electric spas are typically the largest electrical load in homes that have one. In recent years, the California Energy Commission’s California code of regulations, Title 20 has been revised to regulate the maximum allowable standby power for a portable electric spa based on the spa volume. The goal of this regulation is to require improvements to the lowest performing models, for which simple and cost effective improvements are readily available, without eliminating average or better performing products. In this research, the standby power of twenty seven portable electric spas was measured and compared to the Title 20 requirement. These tests resulted in nine of the twenty seven spas not meeting the allowable standby power. Analysis demonstrates that simple and inexpensive improvements to these nine spas would likely cause the spas to pass the Title 20 requirement. Additionally, temperature normalization developed in this research have been adopted by the California Energy Commission and included in revisions to Title 20.
2

Instrumentation of a Savonius wind turbine

Babb, Samuel Martin. January 1979 (has links)
Call number: LD2668 .T4 1979 B32 / Master of Science
3

Real-time phasor measurements for improved monitoring and control of power system stability

Baldwin, Thomas L. 06 June 2008 (has links)
This thesis investigates the use of real-time phasor measurements for voltage and transient stability monitoring and control. Taking advantage of the ability of a Phasor Measurement Unit (PMU) placed at a bus to sample at a fast rate the voltage and current phasors of that bus) various schemes for placing PMU's are considered and evaluated. These schemes include coherency based methods and pilot point placement techniques for system controllability. A novel scheme is proposed which places a minimal set of PMU's so as to make the system measurement model observable, and thereby linear. This placement scheme is derived from the topological observability theory. It concerns the building of a spanning measurement sub-graph across the system with actual or pseudo-measurement assigned to each of its branches. The minimal PMU set is found through a dual search algorithm which uses both a modified bisecting search and a simulated annealing-based method. The former fixes the number of PMU's while the latter look for a placement set that leads to an observable network. In order to accelerate the procedure, an initial PMU placement is provided by a graph-theoretic procedure which builds a spanning measurement sub-graph according to a depth-first search. From computer simulation results performed on various test systems, it appears that only one fourth of the system buses need to be provided with PMU's in order to make the system observable. In an effort to reduce the computing time of transient stability assessment, a dynamic equivalent is presented, which results from the elimination of the load buses provided with voltage--dependent loads. The elimination is performed through a new version of the Ward equivalencing method. In this approach, the equivalent current injections are expressed in terms of the retained bus angles and a sensitivity matrix. The non-linearity of the load flow model is accounted for through piecewise linear approximations by updating the sensitivity matrix whenever the operating point moves beyond the validity of the linearization. The expressions of the incremental changes in the generator electric power is derived. The study also investigates the possibility of using the telemetered data provided by the PMU's during pre-fault and post-fault operating conditions in conjunction with a. new version of the Extended Equal Area Criterion (EEAC) method. The latter is able to handle complex loads through the dynamic Ward equivalencing method. The performance of the approach is illustrated on three test systems which have been reduced to the internal generator nodes. / Ph. D.
4

Uso de instrumentação virtual para a analise da qualidade da energia eletrica / Use of virtual instrumentation for analysis of power quality

Moreira, Alexandre Candido, 1981- 28 August 2006 (has links)
Orientadores: Sigmar Maurer Deckmann, Fernando Pinhabel Marafão / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e Computação / Made available in DSpace on 2018-08-07T06:01:54Z (GMT). No. of bitstreams: 1 Moreira_AlexandreCandido_M.pdf: 4879981 bytes, checksum: 6aa206d50e7569915efea8d3f32bd2c3 (MD5) Previous issue date: 2006 / Resumo: O presente trabalho avalia a possibilidade da aplicação de instrumentação virtual para a análise de problemas da qualidade da energia elétrica (QEE). Aproveitando-se da grande flexibilidade, elevada capacidade de processamento e da facilidade de reconfiguração oferecida por tal tipo de instrumento, são desenvolvidos algoritmos para medição digital e análise de grandezas elétricas. No modo de medição, é feita uma análise comparativa entre os dois principais métodos apresentados na literatura, para o cálculo de potência e fator de potência em sistemas trifásicos com condutor de retorno (neutro). Para comparar esses métodos, foram implementadas sub-rotinas para identificação das componentes fundamentais, de seqüência positiva das tensões e correntes, potências ativa e não-ativa, além de algoritmos para calcular o fator de desequilíbrio da componente fundamental e o nível de distorção harmônica total. No modo de análise, foi implementado um algoritmo que realiza uma varredura nos indicadores de QEE, calculados de minuto em minuto e salvos em arquivos, através do instrumento de medição para uma análise estatística diária (baseada na função de distribuição de amostras).Tal algoritmo permite identificar os principais distúrbios que ocorrem em determinada instalação como também permite avaliar a duração das violações dos limites pré-fixados / Abstract: This work explores the possibility of applying virtual instrumentation to analyze power quality problems. Based on the great flexibility, increased processing capacity and the possibility of reconfiguration, offered by such type of instrumentation, several digital algorithms have been developed for digital measurement and analysis of electrical quantities. In the case of measurement mode, a comparison is made between the two main methods reported in the literature concerning power and power factor calculation in three-phase systems with return conductor (neutral). To compare those methods, sub-routines have been implemented to identify the fundamental components, positive sequence of voltages and currents, active and non-active powers, as well as to calculate the unbalanced factor of the fundamental component and the total harmonic distortion. In the case of analysis mode, an algorithm was implemented that realizes a sweeping of the power quality indices, obtained minute by minute, and automatically stored in files by the instrument, for daily statistical analysis (based on distribution function). Such algorithm helps to identify the main disturbing causes in a specific installation, and permits to evaluate the violation time of the prescribed limits / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica
5

Bezkontaktní zatěžování a měření vysokootáčkových strojů / Contactless loading and measurement of high-speed machines

Vojče, Zbyněk January 2018 (has links)
Práce se zabývá problematikou měření momentu u velmi vysokootáčkových strojů. Z důvodů vysokých rychlostí jsou tradiční metody měření momentu nepoužitelné, z tohoto důvodu je nutno vyvinout novou bezkontaktní metodu. Pro měření je zvolena metoda zatěžování vířivou brzdou, pro kterou je proveden analytický výpočet jejích vlastností pomocí Maxwellových rovnic a je vytvořen model vířivé brzdy v programu FEMM a Ansys/Maxwell 2D. Na závěr jsou výsledky simulací a výpočtů porovnány s měřením na prototypech brzdy.
6

Monitorovací a kontrolní systém pro domácnost / Monitoring and control system

Taťák, Martin January 2016 (has links)
This thesis discusses the topic of internet of things and its protocols and compatible devices in the field of home automation. Also defines the requirements for the system which designs in the form of concept and afterward makes practical realization.
7

Pneumatic power measurement of an oscillating water column converter

Kooverji, Bavesh 04 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: A measurement device was developed to accurately determine the pneumatic power performance of an Oscillating Water Column (OWC) model in a wave flume. The analysis of the pneumatic power is significant due to the wave-topneumatic energy being the primary energy conversion process and where the most energy losses can be expected. The aim of the research study is to address the accurate pneumatic power measurement of unsteady and bidirectional airflow in OWC model experiments. The two fundamental measurements required for the pneumatic power measurement are the pressure difference over an orifice on the OWC model and the volumetric flow rate of air through the outlet. The designed, constructed and assembled measurement device comprised of a venturi flow meter, containing a hot-film anemometer, which could measure the pressure drop and the volumetric flow rate in one device. The assembled pneumatic power measurement device was calibrated in a vertical wind tunnel at steady state. The results from the calibration tests showed that the volumetric flow rate measurements from the pneumatic power measurement device was accurate to within 3 % of the wind tunnel’s readings. The pneumatic power measurement device was incorporated onto a constructed Perspex physical model of a simple OWC device. This assembled system was used as the test unit in the wave flume at Stellenbosch University (SUN). The results from the experimental tests underwent comparative analysis with three analytical OWC air-flow models which were simulated as three scenarios using Matlab Simulink. These results showed that the measurement device has the ability to measure the pneumatic power but there is difficulty in modelling the complex air-flow system of the OWC device. This results in varying levels of agreement between the experimental and simulated pneumatic power results. The research study has revealed that there is difficulty in designing an accurate device for a wide range of test parameters due to the variance in output values. The unsteady and bidirectional nature of the air flow is also difficult to accurately simulate using a one-dimensional analytical model. Recommendations for further investigation are for CFD systems to be used for the analysis of the air-flow in an OWC system and to be used to validate future pneumatic power measurement devices. / AFRIKAANSE OPSOMMING: ‘n Meetinstrument was ontwikkel om die pneumatiese kraglewering van ‘n model van die Ossillerende Water Kolom (OWK) golfenergie omsetter in ‘n golf tenk akkuraat te meet. Dit is belangrik om die omskakeling van golf na pneumatiese energie te analiseer siende dat die grootste energieverlies in dié proses plaasvind. Die doel van hierdie navorsingsprojek was om die akkurate pneumatiese kragmeting van variërende en twee-rigting vloei van lug in ‘n OWK model na te vors. Die twee fundamentele metings wat benodig word vir die pneumatiese kragbepaling is die drukverskil oor die vloei vernouing en die volumetriese vloeitempo van lug deur die uitlaat van die toetstoestel. Die spesiaal ontwerpte meettoestel wat gebruik is in die eksperiment het bestaan uit ‘n venturi vloeimeter wat ‘n verhitte-film anemometer bevat het wat die drukverandering en die volumetriese vloeitempo kan meet in ‘n enkele instrument. Die pneumatiese kragmeting was gekalibreer in ‘n vertikale windtonnel waarin ‘n konstante vloei tempo geïnduseer was. Die kalibrasieproses het bevestig dat die meettoestel metings lewer met ‘n fout van minder as 3 % wanneer dit vergelyk word met die bekende konstante vloei tempo soos bepaal in die windtonnel. ‘n Fisiese model van ‘n vereenvoudigde OWK golfenergie omsetter was ontwerp en gebou uit Perspex om as toetstoestel te gebruik vir die evaluering van die ontwerpte pneumatiese kraglewering meettoestel. Die toetse was uitgevoer in ‘n golftenk by die Universiteit Stellenbosch (SUN). The toetsresultate was vergelyk met drie ander OWK lugvloei modelle wat gesimuleer was deur om die analitiese modelle op te stel en te simuleer in Matlab Simulink. Die vergelyking van modellering resultate het gewys dat die meettoestel die vermoë het om pneumatiese krag te meet. Daar was wel komplikasies met die modellering van die komplekse lugvloei in die OWK toestel, die resultate het geen definitiewe ooreenstemming gewys tussen die eksperimentele en gesimuleerde pneumatiese krag resultate nie. Die navorsingsprojek het gewys dat daar komplikasies is om ‘n enkel toestel te ontwerp wat oor ‘n wye bereik kan meet weens die variasie van die verskillende parameters. Die variërende en twee-rigting lugvloei is ook moeilik om akkuraat te simuleer met ‘n een-dimensionele analitiese simulasie model. Aanbevelings vir verdere navorsing sluit in om die lugvloei in die OWK stelsel te modelleer en te analiseer in ‘n drie-dimensionele model om die lesings van ‘n pneumatiese krag meettoestel te bevestig.
8

Analýza koaličního chování stran na krajské úrovni / Analysis of Coalition Behaviour of Political Parties at the Regional Level

Blížkovský, Radek January 2013 (has links)
Need to form a coalition accompanies most of legislative bodies in multi-party systems without directly-elected executive, including party system in the Czech Republic. This thesis analyses coalition building processes and coalitions formed after regional elections in 2000, 2004, 2008 and 2012. Main goal is to identify what factors, trends and party behaviour patterns affects coalitions bargaining and final form of a coalition. Secondary goal is to evaluate the stability and continuity of these factors and trends. In order to achieve these goals, diachronic and synchronous comparative analyses was used together with quantitative method of voting power measurement. Text is divided into four chapters. First chapter is devoted to discussion about American and European approach to the study of theory of coalitions. Two points of view of motivation of political parties to compete in the elections are presented: Office and Policy seeking. Second part of this chapter is focused on multi-level governance with emphasis on specifics of the coalition formation process and relationships between parliamentary and regional systems. Second chapter presents method of voting power indices. In the third chapter regional political system of Czech Republic, its organs, powers and voting system are described. Final chapter contains the analysis of coalitions and coalition bargaining. Chapter is divided into two parts; one focused on coalition formation in particular regions and second analyzes continuous and long-term factors and trends.
9

Přesná měření střídavých proudů / Accurate AC Current Measurements

Nováková Zachovalová, Věra January 2013 (has links)
In recent years precision measurement of alternating currents goes through large progress especially because of improvements in metrology of electric power, which is related to reduction of electricity consumption. Therefore, more precise measurement of electric energy, power and power quality is required. Measurement range is extending and number of measured frequency points is growing up to 100 kHz. Development of current to voltage transducer with normalized output voltage (0,5 V - 1 V) is in progress because of their easy integration in different measuring systems.. From big area of alternating current metrology this dissertation focuses on development of improved cage shunts for measurement of alternating currents in range 10 mA - 100 A, 10 Hz - 100 kHz. Main objective of this dissertation is to develop theoretical model of existing cage shunts, which will assist design of new improved cage shunts construction. In this dissertation the analytical model of CMI’s cage shunts was established, based on calculating of trans-impedance from cascade matrix of passive two-port which is representing the shunt. Trans-impedance can be used for AC-DC difference and phase error calculation, which are two basic parameters of shunts. Uncertainty analysis of the model was done by means of Monte Carlo method. Next, this dissertation also concentrates on suitable measurement methods of phase error, AC-DC difference, and power a temperature coefficient of resistance. These measurements method were used for calibration of existing CMI’s cage shunts and so the model’s verification was made. Finally, theoretical optimization of existing CMI’s cage shunts constructions and theoretical designs of 20A, 50A and 100A shunts were done using sensitivity analysis results.
10

Evaluation and Design of Noise Control Measures for a Pneumatic Nail Gun

Jayakumar, Vignesh 02 June 2015 (has links)
No description available.

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