Search results for "Transformer"
showing 10 items of 96 documents
Fraunhofer diffraction patterns from apertures illuminated with nonparallel light in nonsymmetrical Fourier transformers.
1985
In a recent paper, a 2-D axially nonsymmetrical Fourier transforming with an anamorphic system was presented. This work extends its performances with the use of spherical illumination. The results provide the conditions to obtain an exact Fourier transform and a greater angular magnification coefficient than with parallel illumination. Experimental results of the latter are shown.
Magnetic potential of transformer window
1996
We describe how to calculate the magnetic potential in the window of an ideal transformer. The knowledge of this potential is a starting point for the determination of some other quantities of practical importance (such as leakage field, overheating of windings, circular currents, additional losses, short circuit forces in windings, etc.).
Characterization of Current Transformers in the Presence of Harmonic Distortion
2008
The CTs performance under distorted conditions are usually characterized by means of the frequency response test. In this paper a new way to characterize CTs, closer to real operative conditions, is proposed. The harmonic phase angle and ratio errors are measured when the CTs are excited with a nonsinusoidal current composed of a fundamental and one harmonic, with adjustable phase shift. The errors measured using the new approach were found larger than the ones obtained with the frequency response. This suggests that frequency response is not a reliable method to evaluate the CT performance under distorted conditions.
Magnetic field analysis and leakage inductance calculation in current transformers by means of 3-D integral methods
1996
This paper presents 3D integral approach to power current transformer magnetic field and inductance calculations. A minimization of the kernel norm has been carried out for the integral equation governing the field. The software package TRACAL3, based on the integral methods for field and inductance calculations, has been developed and implemented for personal computers. The application of the 3D mathematical models has been made for the leakage field in a current transformer. The results of calculations were compared with measurement data. The comparison yields good agreement.
Simulation of forces and 3-D field arising during power autotransformer fault due to electric arc in HV winding
2002
Forces and three-dimensional magnetic fields in high-voltage winding due to an internal short circuit in a power autotransformer are calculated with the computer package OPERA 3D. The considered damage was caused by an electric arc. The materialized deformation of the winding part confirms the simulation results.
Real-time optical spectrum analyzers operating with spectrally incoherent broadband continuous-wave light source
2007
On the framework of coherence theory we discuss the averaged temporal intensity output provided by real-time optical Fourier transformers when the spectral line shape of the stationary source is considered. Some numerical examples are given and the deviations from perfectly monochromatic sources are pointed out.
Estimating Grass Sward Quality and Quantity Parameters Using Drone Remote Sensing with Deep Neural Networks
2022
Funding Information: Funding: This research was funded by Academy of Finland ICT 2023 Smart‐HSI—“Smart hyper‐ spectral imaging solutions for new era in Earth and planetary observations” (Decision no. 335612), by the European Agricultural Fund for Rural Development: Europe investing in rural areas, Pohjois‐ Savon Ely‐keskus (Grant no. 145346) and by the European Regional Development Fund for “Cyber‐ Grass I—Introduction to remote sensing and artificial intelligence assisted silage production” pro‐ ject (ID 20302863) in European Union Interreg Botnia‐Atlantica programme. This research was car‐ ried out in affiliation with the Academy of Finland Flagship “Forest‐Human‐Machine Interplay— Buildi…
Fake News Spreaders Detection: Sometimes Attention Is Not All You Need
2022
Guided by a corpus linguistics approach, in this article we present a comparative evaluation of State-of-the-Art (SotA) models, with a special focus on Transformers, to address the task of Fake News Spreaders (i.e., users that share Fake News) detection. First, we explore the reference multilingual dataset for the considered task, exploiting corpus linguistics techniques, such as chi-square test, keywords and Word Sketch. Second, we perform experiments on several models for Natural Language Processing. Third, we perform a comparative evaluation using the most recent Transformer-based models (RoBERTa, DistilBERT, BERT, XLNet, ELECTRA, Longformer) and other deep and non-deep SotA models (CNN,…
Predicting Next Dialogue Action in Emotionally Loaded Conversation
2021
This paper reports on creating a neural network model for prediction of the next action in a dialogue considering conversation history, i.e. entities, context variables and emotion indicators marking emotionally loaded user utterances. Several experiments were performed to see how the information about emotions affects the accuracy of the model. For the purposes of these experiments, a dataset containing 206 dialogs in Latvian in the transport inquiry domain was created containing both neutral and emotionally loaded utterances. To see if the proposed next dialogue action prediction model architecture is suitable for other languages, the original Latvian utterances were translated into Engli…
Quantifying residential PV feed-in power in low voltage grids based on satellite-derived irradiance data with application to power flow calculations
2016
AbstractA scheme using satellite-derived irradiance measurements to model the feed-in power of residential photovoltaic (PV) systems in a low voltage distribution grid is described. It is validated against smart meter measurements from a test site with 12 residential PV systems in the city of Ulm, Germany, during May 2013 to December 2014. The PV feed-in power is simulated in a 15-min time resolution based on irradiance data derived from Meteosat Second Generation satellite images by the physically based retrieval scheme Heliosat-4. The PV simulation is based on the nominal power and location of the PV systems as provided by the distribution system operator. Orientation angles are taken fro…