Search results for "grid"
showing 10 items of 792 documents
Analysing the effects of power swing on wind farms using instantaneous impedances
2020
Abstract Most of the grid disturbances happen due to the presence of faults and power swing. This article focuses on power swing in view of the amount of penetration of renewable energy resources especially the wind farms. There are two sections. First section approached power swing by deriving a mathematical expression which would be able to track the locus of impedance in time domain and subsequently analyze resistance and reactance simultaneously with respect to time. It used a grid comprising of generator, transmission line and load. The derived expression was compared with a power swing generated using RTDS model and the results were analyzed in R-X plane. Second section analyses the i…
The New "Maximum Yield Grid" (MYG) Array in Full 3D Resistivity Tomography
2008
Over the past few years geoelectrical prospecting has experienced many innovations, ranging from instrumental refinements to improvement of data interpretation. The consequence of this has been a strong increase in the method s resolution power and, therefore, its field of application has broadened. Nevertheless, the diffusion of 3D surveys in electrical resistivity tomography has been very much limited by the long acquisition time required by this kind of investigation, as compared to 2D ERT or other geophysical exploration methods like GPR. However, 3D ERT has a great advantage in terms of resolution power, that is very important in many applications, such as archeological or cultural her…
El consentimiento informado de los menores de edad en el ámbito sanitario
2021
: El consentimiento informado aparece como un derecho de todo paciente a decidir en el ámbito sanitario. En este marco, es necesario determinar si los menores de edad han de ejercitar este derecho o si, por el contrario, precisan de la intervención de un tercero para llevarlo a cabo. A este respecto, nuestra legislación actual reconoce, con carácter general, el derecho a decidir de este colectivo. No obstante, en ocasiones pueden producirse limitaciones a su ejercicio motivadas bien por la ausencia de capacidad real, bien por el principio de interés superior. En definitiva, se trata de alcanzar el mayor beneficio para los menores de edad en el campo de la salud, evitando que se produzcan pe…
Delimitación y características de las áreas rurales en los municipios y las provincias españolas
2016
Este artículo pretende establecer criterios para delimitar de modo riguroso qué es lo que constituye un territorio rural o urbano, dadas las limitaciones de las metodologías tradicionales. En segundo lugar, se propone una tipología rural/urbana a escala municipal para España tomando en consideración tres criterios: la demografía – combinando densidades con umbrales mínimos de población -, la información sobre coberturas y usos del suelo y el grado de accesibilidad desde el mundo rural a las ciudades. Tras establecer la existencia de seis tipos distintos de municipios se procede a una caracterización de las provincias españolas en cuatro categorías diferentes haciendo uso de un análisis clús…
Dynamic mean absolute error as new measure for assessing forecasting errors
2018
Abstract Accurate wind power forecast is essential for grid integration, system planning, and electricity trading in certain electricity markets. Therefore, analyzing prediction errors is a critical task that allows a comparison of prediction models and the selection of the most suitable model. In this work, the temporal error and absolute magnitude error are simultaneously considered to assess the forecast error. The trade-off between both types of errors is computed, analyzed, and interpreted. Moreover, a new index, the dynamic mean absolute error, DMAE, is defined to measure the prediction accuracy. This index accounts for both error components: temporal and absolute. Real cases of wind …
Model Predictive Control for Shunt Active Filters With Fixed Switching Frequency
2016
This paper presents a modification to the classical Model Predictive Control algorithm, named Modulated Model Predictive Control, and its application to active power filters. The proposed control is able to retain all the advantages of a Finite Control Set Model Predictive Control whilst improving the generated waveforms harmonic spectrum. In fact a modulation algorithm, based on the cost function ratio for different output vectors, is inherently included in the MPC. The cost function-based modulator is introduced and its effectiveness on reducing the current ripple is demonstrated. The presented solution provides an effective and straightforward single loop controller, maintaining an excel…
MAGIC-5: an Italian mammographic database of digitised images for research
2008
The implementation of a database of digitised mammograms is discussed. The digitised images were collected beginning in 1999 by a community of physicists in collaboration with radiologists in several Italian hospitals as a first step in developing and implementing a computer-aided detection (CAD) system. All 3,369 mammograms were collected from 967 patients and classified according to lesion type and morphology, breast tissue and pathology type. A dedicated graphical user interface was developed to visualise and process mammograms to support the medical diagnosis directly on a high-resolution screen. The database has been the starting point for developing other medical imaging applications,…
Effect of innervation zones in estimating biceps brachii force-EMG relationship during isometric contraction
2012
Measuring muscle forces in vivo is invasive and consequently indirect methods e.g., electromyography (EMG) are used in estimating muscular force production. The aim of the present paper was to examine what kind of effect the disruption of the physiological signal caused by the innervation zone has in predicting the force/torque output from surface EMG. Twelve men (age 26 (SD ±3)years; height 179 (±6)cm; body mass 73 (±6)kg) volunteered as subjects. They were asked to perform maximal voluntary isometric contraction (MVC) in elbow flexion, and submaximal contractions at 10%, 20%, 30%, 40%, 50% and 75% of the recorded MVC. EMG was measured from biceps brachii muscle with an electrode grid of 5…
Location of Gliomas in Relation to Mobile Telephone Use: A Case-Case and Case-Specular Analysis
2011
The energy absorbed from the radio-frequency fields of mobile telephones depends strongly on distance from the source. The authors' objective in this study was to evaluate whether gliomas occur preferentially in the areas of the brain having the highest radio-frequency exposure. The authors used 2 approaches: In a case-case analysis, tumor locations were compared with varying exposure levels; in a case-specular analysis, a hypothetical reference location was assigned for each glioma, and the distances from the actual and specular locations to the handset were compared. The study included 888 gliomas from 7 European countries (2000-2004), with tumor midpoints defined on a 3-dimensional grid …
Un approccio semplificato per il calcolo del load flow nelle smart grids basato su misure distribuite in bassa tensione
2017
I sistemi di misura distribuiti sono alla base delle "smart distribution grids", ove la crescente presenza di generazione distribuita e sistemi di accumulo e la conseguente transizione verso sistemi attivi rendono necessarie funzionalità avanzate di monitoraggio, controllo e gestione delle reti. In tale contesto, un elemento essenziale è l'analisi dei flussi di potenza, che, com'è noto, può essere effettuata tramite algoritmi di load flow, noti il modello della rete e le potenze generate/assorbite nei vari nodi. Per la misura di tali grandezze sulla media tensione (MT), si possono utilizzare diversi strumenti (quali phasor measurement units, smart meters, power quality analyzers), che però …