Simplified Analytical Calculation of PM Machines Magnetic Flux Leakage Factor

The permanent magnets used for generation of magnetic field in permanent magnet machines are placed in more or less magnetically conducting environment – electrical steel and air. This causes leakage of the magnetic flux from its desired path through the air gap. This paper describes simplified analytical calculation of magnetic properties of five most commonly used placements of permanent magnets and compares obtained leakage factors. A verification of the results via finite element method is also included

Design and Simulation of High Performance Parallel Architectures Using the ISAC Language

Most of modern embedded systems for multimediaand network applications are based on parallel data streamprocessing. The data processing can be done using very longinstruction word processors (VLIW), or using more than onehigh performance application-specific instruction set processor(ASIPs), or even by their combination on single chip.Design and testing of these complex systems is time-consumingand iterative process. Architecture description languages (ADLs)are one of the most effective solutions for single processor design.However, support for description of parallel architectures andmulti-processor systems is very low or completely missing innowadays ADLs. This article presents utilization of newextensions for existing architecture description language ISAC.These extensions are used for easy and fast prototyping andtesting of parallel based systems and processors

Effects of bark beetle disturbance on soil nutrient retention and lake chemistry in glacial catchment

Forest ecosystems worldwide are subjected to human-induced stressors, including eutrophication and acidification, and to natural disturbances (for example, insect infestation, windstorms, fires). The occurrence of the later is expected to increase due to the ongoing climate change. These multi-stressor forcings modify ecosystem biogeochemistry, including the retention of limiting nutrients, with implications for terrestrial and aquatic biodiversity. Here we present whole ecosystem nutrient (N, Ca, Mg, K) mass balances in the forested catchment of Plešné Lake, CZ, which has undergone transient changes linked to the recovery from anthropogenic acidification and to the forest disturbances caused by severe infestations by the bark beetle (Ips typographus). Measured fluxes and storage of nutrients in the lake-catchment ecosystem were used to constrain the processoriented biogeochemical model MAGIC (Model of Acidification of Groundwater In Catchments). Simulated lake water chemistry and changes in soil nutrient pools fitted observed data and revealed that (1) the ecosystem N retention declined, thus nitrate leaching increased for 10 years following the bark beetle disturbance, with transient adverse effects on the acid–base status of lake water, (2) the kinetics of nutrient mineralisation from decaying biomass coupled with nutrient immobilisation in regrowing vegetation constrained the magnitude and duration of ecosystem losses of N, Ca and Mg, (3) the excess of mineralised base cations from decomposing biomass replenished the soil cation exchange matrix, which led to increased soil base saturation, and (4) the improvement of the catchment soil acid–base status led to an increase of lake water pH and acid neutralising capacity. Forested ecosystems underlain by nutrient-poor soils and bedrock are prone to human-induced damages caused by acidification and eutrophication, and any natural disturbance may further lead to nutrient imbalances. We demonstrated that in this natural forest ecosystem protected from human intervention, disturbances together with natural post-disturbance vegetation recovery have temporally positive effects on the nutrient stores in the soil

Určení parametrů náhradního schématu asynchronního stroje v programu FEMM

This work deals with problems of determination of parameters of induction machine's substitution diagram using finite element method software FEMM. There are determined parameters of subtitution diagram corresponding both with stator and rotor (leakage inductances and resistivities) and magnetizing inductance

Výbušné vlastnosti směsí plynů, par hořlavých kapalin a průmyslových prachů a stanovení nebezpečí výbuchu

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Simplified Analytical Calculation of PM Machines Magnetic Flux Leakage Factor

The permanent magnets used for generation of magnetic field in permanent magnet machines are placed in more or less magnetically conducting environment – electrical steel and air. This causes leakage of the magnetic flux from its desired path through the air gap. This paper describes simplified analytical calculation of magnetic properties of five most commonly used placements of permanent magnets and compares obtained leakage factors. A verification of the results via finite element method is also included

Induction machines efficiency mapping

The paper presents a simple yet powerful method of efficiency mapping of induction machines. The whole calculation process is based on knowledge of induction machine equivalent circuit parameters and approximation of losses based on known dependencies on speed, current and magnetic flux linkage. The proposed method is then verified on two samples of electric machines - large industrial induction machine and a sample of a traction induction machine

Design, construction and measurement of an educational synchronous machinery

The paper deals with a complete manufacture of a synchronous machinery for educational purposes. The main target of the design is creation of a machinery which clearly shows all constructional components of used machines, its overall dimensions allow easy transportation between education rooms and both included machines are also fully functional samples of synchronous machines. The paper includes basic information about electromagnetic design of both machines coupled in the machinery and their calculated characteristics. The electromagnetic design is supplemented by mechanical design of the whole display stand with regard to achieve access to each part of manufactured machines. Calculated data are further compared with results of tests performed on manufactured machinery

Parallel winding of a synchronous generator

The paper deals with the design of seven times parallel synchronous generator winding. The parallel winding is not commonly used for synchronous generators because it could be a possible source of difficulties, especially compensatory currents. The paper mentions the design, simulations, manufacturing and results of a measurement performed in a power plant