Search results for "ripple"

Practical Implementation of a Synchronous PWM Strategy for Low Switching Frequency FOC of im Drives with ATSAM3X8E Microcontroller

2021

This paper presents a practical implementation of synchronous PWM modulation algorithm for an induction motor field oriented control powered by a DC/AC inverter and implemented on a low-cost microcontroller, the ATSAM3X8E. In particular, a simple algorithm, capable to calculate automatically an optimized set of frequency modulation indexes will be presented. Hysteresis bands are also introduced in the algorithm in order to avoid multiple changeovers during modulation index transitions. Experimental tests and their results will be shown and discussed, highlighting the benefits of the present algorithm, such as reduction of current harmonic content, reduction of current ripple and, consequent…

Kriptovalūtu volatilitātes modelēšana un prognozēšana

2018

Maģistra darbā ir veikta GARCH volatilitātes modelēšana četrām, pēc tirgus kapitalizācijas, lielākajām kriptovalūtām: Bitcoin, Ethereum, Litecoin un Ripple. Darba empīriskajā daļā, tiek veikta kriptovalūtu GARCH, TGARCH, EGARCH un PGARCH modelēšana un prognozēšana izmantojot normālo un stjūdenta t sadalījumus, aplūkojot laika periodu no 07.08.2015 līdz 27.03.2018. Labākais modelis tiek noteikts salīdzinot trīs modeļu informācijas kritērijus un modeļu prognozes novērtējumus. Kaut arī stjūdenta t sadalījuma izmantošana uzlaboja modeļu novērtējumu visām četrām kriptovalūtām, tomēr tas ne vienmēr uzlaboja modeļa prognozi. Pēc iegūtajiem rezultātiem var secināt Ripple un Bitcoin EGARCH modeļi pā…

Lateral versus perpendicular segregation in mixed polymer brushes.

2002

Grafting of incompatible polymers on a substrate prevents macrophase separation and the chains self-assemble laterally. Mixed brushes are exposed to different solvents and the morphology is observed via atomic force and x-ray photoemission microscopy. In a nonselective solvent the different species segregate into parallel cylinders ("ripple structure"). Upon exposure to a selective solvent, we encounter a transition to a "dimple" structure, in which the unfavored component forms clusters. Simultaneously, we observe an enhanced perpendicular segregation. The experimental observations are compared to self-consistent field calculations, where qualitative agreement is found.

Most hippocampal CA1 pyramidal cells in rabbits increase firing during awake sharp-wave ripples and some do so in response to external stimulation an…

2020

Hippocampus forms neural representations of real-life events including multimodal information of spatial and temporal context. These representations, i.e. organized sequences of neuronal firing are repeated during following rest and sleep, especially when so-called sharp-wave ripples (SPW-Rs) characterize hippocampal local-field potentials. This SPW-R –related replay is thought to underlie memory consolidation. Here, we set out to explore how hippocampal CA1 pyramidal cells respond to the conditioned stimulus during trace eyeblink conditioning and how these responses manifest during SPW-Rs in awake adult female New Zealand White rabbits. Based on reports in rodents, we expected SPW-Rs to ta…

Trace eyeblink conditioning and extinction contingent to hippocampal ripples in rabbits

2014

Disrupting neural activity related to awake-state sharp wave-ripple complexes prevents hippocampal learning

2012

Oscillations in hippocampal local-field potentials (LFPs) reflect the crucial involvement of the hippocampus in memory trace formation: theta (4–8 Hz) oscillations and ripples (~200 Hz) occurring during sharp waves are thought to mediate encoding and consolidation, respectively. During sharp wave-ripple complexes (SPW-Rs), hippocampal cell firing closely follows the pattern that took place during the initial experience, most likely reflecting replay of that event. Disrupting hippocampal ripples using electrical stimulation either during training in awake animals or during sleep after training retards spatial learning. Here, adult rabbits were trained in trace eyeblink conditioning, a hippoc…

Improved High-Fidelity IPMSM mathematical model Including Saturation, Cross-Coupling, Torque Ripple and Iron Loss effects

2022

For enhanced control algorithm design purposes, accurate and high-fidelity electrical machine mathematical models are fundamentals. Usually, accurate evaluation of electrical machine behaviour requires finite element analysis (FEA) with consequent high-computational times. This paper presents an improved high-fidelity Interior Permanent Magnet Synchronous Machine (IPMSM) mathematical model including saturation, cross-coupling, torque ripple and iron loss effects. This model has been implemented in Matlab®/Simulink environment and its parameters are implemented by the use of lookup tables. To validate the modelling approach proposed, a comparative analysis between the proposed Matlab®/Simuli…

Impact Evaluation of Innovative Selective Harmonic Mitigation Algorithm for Cascaded H-Bridge Inverter on IPMSM Drive Application

2021

This paper presents a detailed analysis of the use of a novel Harmonic Mitigation algorithm for Cascaded H-Bridge Multilevel Inverter in electrical drives for the transportation field. For this purpose, an enhanced mathematical model of Interior Permanent Magnet Synchronous Motor (IPMSM), that takes into account simultaneously saturation, cross-coupling, spatial harmonics, and iron loss effects, has been used. In detail, this model allows estimating accurately the efficiency and the torque ripple of the IPMSM, crucial parameters for transportation applications. Moreover, two traditional pulse width modulation strategies, Sinusoidal Phase-Shifted and Switching Frequency Optimal Phase-Shifted…