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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

Methods for Rapid Estimation of Motor Input Power in HVAC Assessments

Christman, Kevin D. 2010 May 1900 (has links)
In preliminary building energy assessments, it is often desired to estimate a motor's input power. Motor power estimates in this context should be rapid, safe, and noninvasive. Existing methods for motor input power estimation, such as direct measurement (wattmeter), Current Method, and Slip Method were evaluated. If installed equipment displays input power or average current, then using such readings are preferred. If installed equipment does not display input power or current, the application of wattmeters or current clamps is too time-consuming and invasive for the preliminary energy audit. In that case, if a shaft speed measurement is readily available, then the Slip Method is a satisfactory method for estimating motor input power. An analysis of performance data for 459 motors suggests comparable performance for predicting normalized (to the nominal motor input power) motor input power with the Current and Slip Methods: 10.0% and 9.9% RMSE, respectively. Both of these methods may be improved by applying regression on the predicted variable and/or nameplate parameters. For example, the Slip Method could be improved by applying a second-order regression, thereby reducing the predicted load factor residual RMSE of the data set from 9.0% to 8.2%. The Current and Slip Methods were also evaluated on two real motors. The normalized (to the nominal motor input power) predicted input power RMSE for the Current Method was on average 15% for the two motors; for the Slip Method the corresponding average was 17.5%. In some cases, shaft speed measurements may not be available. A temperature-based approach for estimating motor input power was investigated. Other required parameters include ambient temperature, motor efficiency, and a motor thermal constant. The temperature approach offers quick, safe, and non-invasive motor power estimation. However, thermal coefficients may vary significantly across motors and a model to predict the thermal coefficients has yet to be developed. Furthermore, the temperature approach has a very strong dependence on motor efficiency uncertainty. Experiments were performed on two motors to determine their motor thermal constants. If a motor's thermal constants and running efficiency are known, then this method gave motor input power estimates with a RMSE (normalized to the nominal input power) on the order of 4% for the studied motors.
2

Predikce stavu nabití olověných akumulátorů / State of charge prediction of lead acid batteries

Chochola, Ondřej January 2010 (has links)
The general aim of the thesis is a detailed examination of battery charging condition possibility of lead-acid accumulator with the help of pulse current method. The methodology consists of experimental cell testing by pulse battery charging and pulse battery discharging during a progressive change of charging and discharging current as well as charging and discharging time change. The testing procedure proceeds at a various battery charging condition. Principal aim of this work is to compare final voltage dependencies and to establish the usability of pulse current method to determine battery charging condition.
3

Testovací parametry a podmínky amorfních fotovoltaickách panelů / Test parameters and conditions of amorphous photovoltaic modules

Kostelník, Adam January 2014 (has links)
This master’s thesis deals with the problem of thin film solar cells, their parameters and measuring. The introductory chapter describes the properties of individual thin-film technology, summarizes their advantages against the crystalline silicon cell. Another chapter is exclusively focused on thin-film cells based on amorphous silicon. There is described the manufacturing processes of amorphous cells and modifications performed during the manufacturing. One part of master’s thesis is dedicated to the description of basic electrical quantities and PV cell degradation mechanisms that negatively affect these electrical properties. It is explained in detail the most important degradation phenomenon called Steabler - Wronski effect. The master’s thesis describes standards regarding testing amorphous cells as well as method, how to achieve their performance stability. The practical part is focused on the testing of several single-layer amorphous cells that were exposed to degradation and regeneration effects. One part of the thesis is studying of a new method of testing of amorphous cell, where is necessary to determine whether it is the degradation or regeneration process. Measured values obtained from several types of measurements were compared, evaluated and displayed in the graphs. The recommendation for future testing of amorphous article is stated in the final chapter.
4

Stavebně technologický projekt výstavby komplexu RD SLAVKOV - Pod Zlatou horou / Construction Project for Implementation of Houses in Slavkov - Pod Zlatou horou

Kurková, Dita January 2020 (has links)
The subject of the diploma thesis is the solution of chosen parts of the construction technology project of the 1st phase of the construction „Komplex RD Slavkov, Pod Zlatou horou“. These are 4 semi-detached houses, overall 8 family houses. The work deals with technological regulations for the superstructure including roof, study of the realization of the construction technology project, design of the main construction machines and mechanisms and control and test plan. For the whole construction is elaborated time and financial plan in two variants, namely the gradual and current method of construction, and a detailed schedule for one semi-detached house. The technical report of the building site equipment is completed with the drawings, itemized budget of the building part of the house, noise study and specialization focused on the photovoltaic system, with an alternative solution to use solar collectors. The thesis also includes a case study of construction methods focused on the gradual and current method of construction.

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