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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.
41

Design of High-density Transformers for High-frequency High-power Converters

Shen, Wei 29 September 2006 (has links)
Moore's Law has been used to describe and predict the blossom of IC industries, so increasing the data density is clearly the ultimate goal of all technological development. If the power density of power electronics converters can be analogized to the data density of IC's, then power density is a critical indicator and inherent driving force to the development of power electronics. Increasing the power density while reducing or keeping the cost would allow power electronics to be used in more applications. One of the design challenges of the high-density power converter design is to have high-density magnetic components which are usually the most bulky parts in a converter. Increasing the switching frequency to shrink the passive component size is the biggest contribution towards increasing power density. However, two factors, losses and parasitics, loom and compromise the effect. Losses of high-frequency magnetic components are complicated due to the eddy current effect in magnetic cores and copper windings. Parasitics of magnetic components, including leakage inductances and winding capacitances, can significantly change converter behavior. Therefore, modeling loss and parasitic mechanism and control them for certain design are major challenges and need to be explored extensively. In this dissertation, the abovementioned issues of high-frequency transformers are explored, particularly in regards to high-power converter applications. Loss calculations accommodating resonant operating waveform and Litz wire windings are explored. Leakage inductance modeling for large-number-of-stand Litz wire windings is proposed. The optimal design procedure based on the models is developed. / Ph. D.
42

Study on the Development of New BWR Core Analysis Scheme Based on the Continuous Energy Monte Carlo Burn-up Calculation Method

東條, 匡志, tojo, masashi 28 September 2007 (has links)
名古屋大学博士学位論文 学位の種類:博士(工学) 学位授与年月日:平成19年9月28日
43

Augalininkystės produkcijos savikainos skaičiavimo metodika / Methodics of Plant Production Cost Calculation

Dereškaitė, Rima 24 May 2005 (has links)
Research object – agricultural enterprises. Research subject – methodics of plant production cost calculation. Research aim – to analyze references and practical methods employed in plant produce cost calculation and to propose methodics improvements of plant production cost calculation. Objectives: 1) to analyze the essence of expenditure and production cost; 5) to examine the structure of production cost and to substantiate the expedience of expenditure calculation into cost; 6) to study methodics of plant production cost calculation in agricultural enterprises; 7) to submit proposals for improvement methodics of plant production cost calculation based on references study and research results. Research methods – logical and comparative analysis and synthesis of literature by Lithuanian and foreign authors, questionnaire questioning of agricultural enterprises, methods of logical and graphic modeling. After the study of produce cost essence, indices and their composition, calculation system and plant produce cost calculation methodology applied at agricultural enterprises, proposals were submitted for improvement methodics of plant production cost calculation.
44

Klimatizace administrativní budovy / Air - conditioning of office building

Birhanzl, Petr January 2011 (has links)
The thesis describes the various ventilation and air conditioning systems used to maintain suitable, temperature-humidity parameters of air in office buildings. The thesis deals with their advantages and disadvantages and assessing the suitability of using several systems for the application. The main task is to choose the most suitable system and it's calculation. For the actual system design is needed to detect a heat loss and gains the specified object and calculate the minimum amount of ventilation air. There will also be given psychrometric calculation of a device and drawing documentation, including draft of an engine room.
45

Jeřábová kočka mostového jeřábu 32 t / Crane trolley 32 t

Knapec, Tomáš January 2015 (has links)
This master’s thesis is the design development of crane trolley, which is used to manipulate with scrap material. The target of this thesis is to develop a technical report including calculations of running and lifting gear, strength calculation of frame of trolley and drawings containing assembly of crane trolley and assemblies of running and lifting gear. Desired parameters of this trolley are maximum load capacity 32 000 kg, lifting height of 11 m, working lifting speed up to 10 m/min and working running speed up to 50 m/min.
46

Matematiklärares val av huvudräkningsstrategier inom addition : En intervjustudie av 6 lärare i Sverige och England

Lübking, Amanda January 2016 (has links)
Studien utgår från en kvalitativt inriktad analys och metod, där syftet är att undersöka vilka huvudräkningsstrategier som 3 svenska respektive 3 engelska lärare undervisar i, inom addition. Det empiriska materialet består av intervjuer som sedan har transkriberats och analyserats. Studien har låtit sig inspireras av ett hermeneutiskt perspektiv kombinerat med Grounded Theory. Hermeneutiskt perspektiv innebär att all data som finns i studien har tolkats och analyserats. Grounded Theory är ett vanligt sätt att analysera kvalitativ data och genom denna teori har kategorier skapats utifrån det resultat som framkommit. Resultatet av studien visar att de svenska lärarnas vanligaste val av strategier är: talsorter var för sig och algoritmer. De engelska lärarnas vanligaste val av strategier är: tiokamrater, additionstabellen och algoritmer. Av resultatet framkommer även de skillnader som finns mellan de intervjuade lärarnas val av strategier. / The study is based on a qualitatively directed method and the main aim is to investigate, and examine the mental arithmetic strategies of both Swedish and English teachers. In particular, the methods they use, to teach addition. The empirical data within this research is based on first hand interviews with six teachers; three from Sweden, and three from England. The study is inspired by a Hermeneutic Perspective in combination with Grounded Theory. The word hermeneutic, means that all of the data contained in the study has been interpreted and analyzed by the researcher. Grounded Theory is a common method used to analyze qualitative data. With this theory, categories have been created on the basis of the results obtained within this study. The results of the study show that Swedish teachers' most common choices of strategies are; partitioning method, and algorithms. In contrast, the English teachers’ strategies are the following; number bonds, the additiontable and algorithms. The results of this study also illustrate the differences between the Swedish and the English teachers’ choices of strategies.
47

An evaluation of coplanar line for application in microwave integrated circuitry

Jeong, Jae Soon 12 1900 (has links)
Approved for public release; distribution is unlimited / A general study of conductor backed coplanar waveguide is presented. The impedance (Z(0)) and effective dielectric constant (ɛ(reff)) of conductor-backed coplanar waveguide (CBCPW) have been calculated by using a variational method and the boundary point matching method. In this present work only the TEM dominant low frequency propagation mode of coplanar line has been considered. Experimental facilities are vector network analyzer (HP8409) and bench-instrument measurements. / http://archive.org/details/evaluationofcopl00jeon / Captain, Korean Air Force
48

Polynomial Expansion-Based Displacement Calculation on FPGA / Polynomexpansions-baserad förskjutningsberäkning på FPGA

Ehrenstråhle, Carl January 2016 (has links)
This thesis implements a system for calculating the displacement between two consecutive video frames. The displacement is calculated using a polynomial expansion-based algorithm. A unit tested bottoms-up approach is successfully used to design and implement the system. The designed and implemented system is thoroughly elaborated upon. The chosen algorithm and its computational details are presented to provide context to the implemented system. Some of the major issues and their impact on the system are discussed.
49

Analýza controllingového modelu společnosti ČD Cargo, a. s. / Analysis of controlling model of CD Cargo, Inc.

Menzelová, Monika January 2010 (has links)
The aim of my work is to evaluate the operation of the controlling model, the company created for the purpose of allocation of costs to revenues, respectively sales contracts, and to find possibilities for improvement. The reason is to evaluate these contracts from various aspects, namely profitability, cost intensive, contribution to overall profit, etc. A key element of the model are the rates determined by using calculations based on the individual activities. Therefore, work is currently focused on refining and possible reducing of calculated rates and also quantifying these changes through analysis. The aim is also to find more appropriate tools that would complete the existing calculation, and that management could use while managing the company. To ensure the effect on rates it has been especially suggested to change an approach to depreciation and labor costs. As the complement of the existing calculation was recommended using the variable costing and the target costing.
50

Kalkulace nákladů v kamionové dopravě / Cost calculation in truck transport

Petr, Martin January 2010 (has links)
Master's Thesis is dealing with cost calculation in truck transport in view of smaller freight and spedition bussines firm which is operating on Czech territory. The main point is to break down cost calculation for all kinds of vehicles, which are owned by analysed firm, relative to the monitored period. Created cost calculation will serve to the employees by price setting for the transport services in future.

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