Modelling and analysis of losses in a permanent magnet synchronous motor

This thesis was done in the Electromechanics group of Department of Electrical Engineering, Aalto University as a part of electromechanics research. Thesis is concentrated on analyzing losses in permanent magnets of concentrated winding, outer rotor with surface mounted magnets of permanent magnet synchronous machine. The approach to establish permanent magnet losses is done via two-dimensional simulation in FEMM software with post-process analytical calculation. To compare results obtained from this approach, simulation in COMSOL Multiphysics environment, purely analytical computation following Attalah’s method and EMDtool simulation is used. EMDtool simulation is taken as a reference, hence it is considering the end effect via hybrid 2D-3D method and solving the electric scalar potential in 3D. Results obtained from thesis method were compared with all mentioned used methods. With using the end effect coefficient, used method shows effective way how to estimate eddy current losses in permanent magnets

The Bronze Age on the Periphery. The hoard from Tichá and new finds from the Upper Malše Basin in Southern Bohemia

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A Head/Taillight Featuring Hybrid Planar Visible Light Communications/Millimetre Wave Antenna for Vehicular Communications

With the emergence of the fifth generation and beyond mobile networks, both visible light communications (VLC) and radio frequency (RF) or millimetre wave (mmW) systems are expected to maintain the connectivity in various environments. In outdoor environments the link (VLC or RF) availability is paramount, which is affected by channel conditions. In particular, in vehicular communications other vehicles, harsh environment, and road geometry and structure will have the impact on the link connectivity and availability. In such cases, a front-end antenna solution, which benefits both optical and RF communication links, can be seen as an attractive option that can be fitted in future vehicles. In this paper, we present the design and practical implementation of a planar hybrid VLC/mmW antenna operating at 20.8 GHz and show measured results for characterization of RF and VLC links as well as communications performance. We have used the widely adopted on-off keying and quadrature amplitude modulation schemes with different orders to demonstrate data rates of 5 Mb/s and up to 100 Mb/s for the VLC and mmW links, respectively. By measuring the bit error rate and the error vector magnitude for VLC and Rf links, respectively for each modulation we have shown that the proposed hybrid planar antenna is suitable for example in a typical vehicle -to-vehicle communications

The usage possibilities of non-destructive analyses on the basis of X-ray radiation in archaeology

X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF) are among the basic methods for evaluation of the inner structure and chemical composition of materials. This paper describes the principles and possibilities of using these methods primarily in archaeology and anthropology. Specific results of analyses of a series of ceramic potsherds and a steel crossbow arrow are presented.X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF) are among the basic methods for evaluation of the inner structure and chemical composition of materials. This paper describes the principles and possibilities of using these methods primarily in archaeology and anthropology. Specific results of analyses of a series of ceramic potsherds and a steel crossbow arrow are presented

Loss of neuronal network resilience precedes seizures and determines the ictogenic nature of interictal synaptic perturbations

The mechanisms of seizure emergence, and the role of brief interictal epileptiform discharges (IEDs) in seizure generation are two of the most important unresolved issues in modern epilepsy research. Our study shows that the transition to seizure is not a sudden phenomenon,but a slow process characterized by the progressive loss of neuronal network resilience. From a dynamical perspective, the slow transition is governed by the principles of critical slowing, a robust natural phenomenon observable in systems characterized by transitions between dynamical regimes. In epilepsy, this process is modulated by the synchronous synaptic input from IEDs. IEDs are external perturbations that produce phasic changes in the slow transition process and exert opposing effects on the dynamics of a seizure-generating network, causing either anti-seizure or pro-seizure effects. We show that the multifaceted nature of IEDs is defined by the dynamical state of the network at the moment of the discharge occurrence

Otázky výroby střednělegovaných ocelí v martinských pecích z hlediska dosažení optimálních jakostních, výrobních i ekonomických výsledků

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Disjunkty v anglické fikci

This bachelor paper deals with disjunct in English fiction. The theoretical firstly defines the general concept of adverbials. Further, it pays attention to describe semantic and syntactic differences between disjuncts and the other grammatical categories of adverbials - adjuncts, conjuncts, and subjuncts. The rest of the theoretical part is aimed to describing semantic roles, syntactic realizations, and positions in which disjuncts may occur. The practical part contrasts the theoretical background with the results of the analysis of authentic texts of the discourse of fiction.Tato práce se zabývá disjunkty v anglické fikci. V teoretické části jsou nejprve představena příslovečná určení. Dále je pozornost věnována vymezení syntaktických a sémantických rozdílů mezi disjunkty a dalšími gramatickými funkcemi příslovečných určení - adjunkty, konjunkty, a subjunkty. Zbytek teoretické práce je zaměřen na popis sémantických rolí, formální realizace a pozicím, ve kterých se mohou disjunkty objevit. V praktické části budou porovnány teoretické poznatky s výsledky analýzy autentického textu.Katedra anglistiky a amerikanistik

Heat transfer in asynchronous machine

Tato bakalářská práce je zaměřena na popis jednotlivých podsystémů asynchronního stroje. V části, kde je popisován izolační systém asynchronního stroje, je práce zaměřena na nové elektroizolační materiály. Dále práce popisuje jednotlivé způsoby šíření tepla v elektrických strojích. Poté je navrhnut výpočet na oteplení statorového svazku a vinutí. V závěru je konfrontován analytický tepelný návrh elektrického točivého stroje na základě náhradní tepelné sítě s výsledky analýzy metodou konečných prvků a měřením.ObhájenoThis bachelor thesis is focused on the description of the subsystems of asynchronous machines. The work is focused on new electrical insulating materials in part where insulation systems of asynchronous machine are described. It also describes the different methods of heat spreading in electrical machines. After that the calculate of temperature rise in the stator winding and pack is designed. In conclusion the analytical thermal design of electrical rotating machines based on alternative heating network is confronted with the results of finite element analysis and measurement

Optimization of the Business Model of the Online Store Jednoručky.cz

This thesis focuses on the analysis and improvement of the business model of a small online store Jednoručky.cz, which sells fitness dumbbells. The aim of the thesis is to reveal the fundamental flaws in the store's strategy, to find the main causes of the decline in sales of this online business and propose changes that will lead to a smooth operation and return to growth of customer orders. The theoretical part describes the basic aspects that are important in the establishment and operation of an online store, followed by the introduction of some current trends in internet marketing and the opportunities that are offered to Czech entrepreneurs to obtain information from this field. The practical part of the thesis describes and evaluates internal processes and strategy of the store Jednoručky.cz and on the basis of these findings, it suggests a comprehensive plan for optimizing its business model. The plan will be realized during the year 2015

Optimální podmínky výroby legovaných ocelí v intensifikovaných martinských pecích

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