638,566 research outputs found
Letter from Professor P. Power to Hagan
No full textHolograph letter from Professor P. Power, University College, Cork, to Hagan, in gratitude for the information given about Archbishop Brenan and for his interest in the matter. Regretting he could not come to Rome at the moment to do research
Note from Reverend Professor P. Power to Hagan
No full textHolograph note from Reverend Professor P. Power, University College, Cork, to Hagan, asking for assistance in finding letters written by Bishop [Brenan] of Waterford and Lismore, in the late 17th century, to Propaganda
Ohio Power Siting Board
No full textTitle from PDF p. [1] (viewed on June 15, 2007).; "Created: 7/6/2004 ..."--Document properties screen.; Brochure. Intended to be printed off on 1 sheet, front and back, and folded in fourths horizontally.; Harvested from the web on 6/15/0
matthew-p-brown/E_cells_2023: E_cells_2024
No full text<p>This page contains the code used to analyze behavior and voltage imaging data from <strong>Brown et al., 2024</strong>. Further questions can be sent to the corresponding author, Dr. Mark N. Wu ([email protected]).</p>
Probabilistic Power Quality Level Forecasting through Quantile Regression Models
No full textWaveform distortions are Power Quality (PQ) disturbances with harmful impacts on power system components, and planning engineers and system operators are deeply interested in new methodologies able to provide a support to limit this impact. The forecasting of PQ indices on voltage and current waveforms is nowadays considered one of the most important tools to provide this support. In this paper, probabilistic forecasting methodologies are proposed, investigated and compared to predict waveform distortion indices with different intervals. The Quantile Regression (QR) model is considered as the underlying forecasting model for predicting the considered PQ index level, and the Principal Component Analysis (PCA) is considered to mitigate the high dimensionality of the forecasting problem that could arise by exploiting data collected by dedicated PQ measurement systems. Numerical applications based on actual data and developed for different lead times give evidence of the suitability of the methodologies and the interest in the obtained results
Battery Storage System as Power Unbalance Redistributor in Distribution Grids Based on Three Legs Four Wire Voltage Source Converter
No full textThis article discusses the application of battery energy storage systems (BESSs) as power redistributors in three-phase distribution grids as an add-on functionality to typical BESS applications, such as congestion management and energy arbitrage. Combining those ancillary services into a single power unit is not yet performed in practice but may constitute an emerging business opportunity to increase the BESS revenues. The unbalanced operation of the BESS voltage source converter (VSC) leads to the circulation of low-frequency current harmonics in the dc-link through the capacitors and the battery cells. Therefore, it is particularly interesting whether relatively large 50- and 100-Hz currents can safely circulate within these components. Analytical modeling and design guidelines for the dc-link of a three-leg four-wire two-level VSC operating under unbalanced loads are detailed. Furthermore, a low-power VSC prototype is used to demonstrate the working principle of the BESS, providing power unbalance redistribution and symmetric power exchange. Additionally, the ICR18650-26F Lithium-ion cells are cycled to reach end-of-life with different current profiles and C-ratings. The analysis shows that charging with a 100 Hz ripple superimposed to the dc current leads to a 10% increment in degradation
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Flexible Power Transfer Network
No full textThe flexible power transfer network is a conceptual transfer network for residential areas. The main advantage of the proposed concept is the increased safety and flexibility compared to currently used AC network. The core idea is to incorporate wireless power transfer into the network which leads to inherently safer and more flexible network compared to 50 Hz AC network. The networkmust be able to supply enough power to several loads without any means of communication between the source and the load side. Furthermore, with introduction of distributed energy sources (eg. PV), the network must also be able to operate several sources at one time. Themain challenge tackled in this thesis was a design of a controller that is able to control several sources simultaneously, independently and efficiently. The controller is the same for each source, which means that there is nomaster and no slave source and each source has the same priority. The solution provided in this thesis is based on the sliding mode control theory and the physics of series loaded resonant converter. The proposed controller is suitable to be used in applications like PV clusters, or other applications with distributed sources. The derivation of the controller proposed in this thesis starts with the energy-balance equation. However, it is realized that in order to control multiple sources with possibly different voltage levels it is important to utilize the reactive power. Therefore, the controller proposed emphasizes the power-balance equation. The dynamic stability of the power-balance controller is studied in the framework of sliding mode control theory.Electrical Engineering, Mathematics and Computer ScienceDC systems, Energy conversion & Storag
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