Iskanje po katalogu digitalne knjižnice

Opis: The analytical and especially the numerical calculations of the magnetic fields of highly saturated electrical machines require a correctly given magnetizing curve. In practice, professional software may use many points of the magnetizing curve (sometimes 50 or more points). There is a high probability that a point will be entered or measured incorrectly. We have therefore set ourselves three objectives. The first is to reduce the number of points given. The second is to ensure that the curve is given analytically (in the form of orthogonal polynomials) and is as smooth as possible. This means that the derivatives of the reluctance are also as smooth as possible. Therefore, the Newton– Raphson iteration procedure in numerical calculations converges rapidly. The third objective was to make the magnetizing curve continue beyond a magnetic field density of 2 T up to about 3 T. Most professional programs simply limit the magnetizing curve to about 2.2 T. This limitation makes it impossible to calculate accurately the magnetic field in the bridges, especially when the slots in the rotor are closed. Local fields can exceed values of 2.2 T. A solution has been found. It uses higher order orthogonal polynomials. It has been shown that 12 given points of the magnetizing curve is enough to give a good approximation of the measured curve. However, one polynomial function is not enough. We need three functions and another exponential function for magnetic field densities above around 2 T up to a value of relative permeability equal to 1. In the numerical calculation of the field, we thus achieve the desired error (residual) vector of the Newton–Raphson iterative procedure in 10 ÷ 15 steps for semi-closed slots and 20 ÷ 30 steps for closed slots.
Ključne besede: induction motors, magnetizing curves, numerical calculation
Objavljeno v DKUM: 10.04.2025; Ogledov: 0; Prenosov: 5
Celotno besedilo (1,89 MB)
Gradivo ima več datotek! Več...

Opis: The aim of this paper is to assess the economic viability of two different bedding materials used in broiler chicken farming processes. The materials considered are wood shavings and slice-dedusted straw. The slice-dedusted straw is considered an alternative type of bedding material produced by a company from Slovenia. While the technological and economic assessment of this type of bedding material has already been researched in the case of horse breeding, it is something new in the case of broiler chicken farming. Data collection is structured from two trials. Trial one (T1) is also known as daily observations, and trial two (T2) involves obtaining input data at the end of the fattening period. During T1, daily observations are focused on collecting data from technical characteristics, and in T2, the percentage of death proportions and average increments are observed, calculated, and considered as economic input data. The cost calculation model is used for the calculation of several different technical-economic indicators, which denote the influence of different bedding materials no economic production viability. Favorable economic results were found for slice-dedusted straw, which shows that this kind of alternative bedding material could be the better option.
Ključne besede: bedding materials, feasibility analysis, broiler chicken, cost calculation model
Objavljeno v DKUM: 02.07.2024; Ogledov: 111; Prenosov: 21
Celotno besedilo (6,19 MB)
Gradivo ima več datotek! Več...

Opis: The basis of this thesis is the tool for power train calculation of battery electric vehicles. With the help of extensive tests and analysis, we discovered the room for possible improvements, which allowed us to upgrade the tool with a better and wider data field. Therefore, the tool is easier for engineers and various users to handle. In addition, we have separated the input file from the solver, which allows safer sharing of the documents, and equipped the input interface with additional logic for handling of wrong inputs. Furthermore, the guidance and tips for the users and additional inputs for alternative data have been added. Comparing the new tool and interface with the previous one, there are significant benefits regarding data accuracy and the difficulty level of its management.
Ključne besede: Battery electric vehicles, power train, power train calculation
Objavljeno v DKUM: 01.12.2020; Ogledov: 1462; Prenosov: 13
Celotno besedilo (1,19 MB)

Opis: In contrast to the investment calculation, that has a project-related, cross-period view the cost accounting refers to individual time slices (meaning usually month, quarter or year ) and is more position oriented, respectively division oriented.
Ključne besede: costs, revenues, calculation, controlling, ecology
Objavljeno v DKUM: 11.05.2018; Ogledov: 1120; Prenosov: 100
Celotno besedilo (815,63 KB)
Gradivo ima več datotek! Več...

Opis: The transport sector represents a vital component of national economies and has significant impacts on productivity and social welfare. In 2012, the transport sector in Europe was estimated to account for 3.7% of the European Gross Domestic Product (GDP) and 5.1% for employment. Road transport proves to be the predominant mode for moving goods within Europe holding a share of approximately 45.8% in 2012 (in ton-kms). In Greece, the share of road freight transport is significantly higher (98%) indicating the importance of this sector for the Greek economy. To this end and considering the existing needs of road freight transport operators in Greece, the objective of this research is to establish an analytical and documented basis for estimating the operating cost of a truck on specific urban or national freight transport routes. To achieve this goal, an extended literature review has been conducted resulting in the identification of the main components comprising the total truck operating cost, which were then updated and validated through a series of personal interviews with selected road freight transport professionals. An excel-based application tool was also developed in order to facilitate operating cost estimates for different cases, through selection of the proper values of the relevant parameters. The resulting tool was used to analyse four test cases, which demonstrate the tool’s usability and applicability. Results from this analysis have been also validated by industry experts and they reflect real-world transport scenarios.
Ključne besede: cost calculation tool, road freight transport, truck operating costs
Objavljeno v DKUM: 17.11.2017; Ogledov: 1490; Prenosov: 347
Celotno besedilo (339,45 KB)
Gradivo ima več datotek! Več...