841 research outputs found
Optimized battery sizing for merchant solar PV capacity firming in different electricity markets
Comunicació presentada a IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society (Lisbon, Portugal 14-17 Oct. 2019)This work analyses the minimum energy capacity requirements to be demanded to battery energy storage systems used in megawatt-range merchant solar PV plants to grant capacity firming. The operation of such a plant is simulated (with a 2-minute time step, at three different locations of the Iberian Peninsula, and for different battery sizes) after solving a quadratic programming optimization problem. The control algorithm takes into account the irradiance forecast and the intraday electricity market configuration, which presents certain peculiarities in the Iberian region with regard to other European markets. The analysis has been performed in an annual basis and current irradiance measured values have been used
Deep learning-based forecasting of the automatic Frequency Reserve Restoration band price in the Iberian electricity market
The replacement of conventional and dispatchable generation technologies by intermittent renewable
energy sources increases the need for ancillary services. New agents, such as batteries, may join
frequency regulation markets but they require accurate information about future market prices and
service demand trends in order to make their participation profitable. This paper proposes and analyzes
the accuracy of various deep learning-based models to estimate the secondary reserve marginal band
price in the automatic frequency restoration reserves service of the Iberian electricity market. First, a
correlation analysis allows determining various subsets of market variables used as model inputs. These
subsets include some highly correlated variables together with different combinations of others whose
influenced is analyzed. Next, three different neural network techniques are considered: feedforward,
convolutional and recurrent networks. For each of them, a random search is performed to obtain the
best set of hyperparameters. The analysis of the results shows how the LSTM model returns the best
performance metrics (63.22 % of mean absolute scaled error), clearly improving the state-of-the-art in
the domain.Funding for open access charge: CRUE-Universitat Jaume
Daily Solar Energy Estimation for Minimizing Energy Storage Requirements in PV Power Plants
This paper proposes an optimized energy management strategy (EMS) for photovoltaic (PV) power plants with energy storage (ES) based on the estimation of the daily solar energy production. This EMS produces a constant-by-hours power reference which mitigates the stochastic nature of PV production typically associated to the solar resource, and enables PV power plants to take part in the day and intraday electricity markets. The possibility of using the intraday market sessions to refine the plant's power reference paves the way to minimizing the energy capacity ratings of the ES system required to operate the PV power plant without incurring excessive production deviations. This proposal is analyzed on an annual basis using actual irradiance data and theoretical irradiance models extracted from official databases
Ansiedad y depresión en una muestra de estudiantes de medicina de San Salvador
Este estudio analiza los niveles de ansiedad y depresión que presenta la población
de estudiantes de medicina de tres universidades, utilizando escalas de referencia
internacional de tamizaje, identificadas como escalas de Beck para ansiedad y
depresión; con el fin de detectar y relacionar los resultados con variables
individuales. La importancia del estudio radica en que el estudiante de medicina es
un trabajador de la salud con responsabilidades académicas el cual está expuesto
a estrés el cual puede desencadenar ansiedad y depresión. Este es un estudio
descriptivo en el que participaron voluntariamente una población de 511
estudiantes de medicina de San Salvador. Los datos analizados sugieren que la
edad, sexo, año de estudio académico, rendimiento académico e ingresos
económicos de los estudiantes se relacionan con la presencia de niveles
adaptativos y/o mórbidos de ansiedad y depresión los cuales deben ser
confirmados, identificados y tratados por profesionales de la salud mental. Se
concluye que casi la mitad de los estudiantes presenta algún nivel de ansiedad, un
cuarto de la población presenta algún nivel de depresión. / ABSTRACT
This research analyze the levels of anxiety and depression that a medical student
population have, using international reference scales for screening, identified as BECK inventories for anxiety and depression; which mainly wants to detect and relate the results with individual variables. The importance of this study lies in the fact that the medical students are workers with academic responsibilities, which are exposed to stress that could trigger anxiety and depression. This is a descriptive study where 511 medical students from San Salvador voluntarily participated. The analyzed data suggest that age, sex, scholar year, academic performance and familiar incomes of the students have a relation with the presence of adaptive or
morbid levels of anxiety and depression, which must be confirmed, identified and treated by mental health qualified professionals. It's concluded that almost the half of the medical student have any level of anxiety, a quart of them have any level of depression.Tesis para optar al Título de Doctor en Medicin
Damage and spatiotemporal dynamics of the Ngaio flat mite, Brevipalpus ferraguti (Trombidiformes: Tenuipalpidae), with observations on the development of the female insemination system
[EN] We studied the Ngaio flat mite, Brevipalpus ferraguti Ochoa & Beard, on Myoporum
laetum (Scrophulariaceae), a common introduced plant used as hedgerows in gardens and
green areas of the Mediterranean, where the mite causes considerable damage. We first
describe the damage, and then the patterns of mite seasonal abundance and spatial distribution.
Finally, we address the development of the female insemination system at the population
level. Damage occurs on both sides of the leaves, starting with a uniform stippling and
bronzing and ending in the leaves drying out and extensive defoliation that coincides with
summer. Mite population peaked between June and August, maintained moderate levels in
autumn and winter and reached its lowest density in early spring. Active motile immatures
and eggs were present throughout the year. Females and motile immature forms were more
abundant on the abaxial (lower) leaf surface, but eggs were deposited on both surfaces
indistinctly, suggesting that females actively move to the adaxial (upper) surface in summer
to oviposit. All the developmental stages were aggregated on the leaves throughout the
year regardless of their population density. Our study suggests that a binomial or presenceabsence
sampling, examining only the number of females on the abaxial surface, can accurately
estimate the total mite density levels. Only 23.5% of females possessed a fully developed
spermatheca, whereas in 76.5% of the cases the seminal receptacle was not present
or not developed. Females with a complete spermatheca were less abundant in summer.
Average temperatures and host plant species affected the occurrence of this reproductive
structure.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.Escobar-Garcia, HA.; Ferragut Pérez, FJ. (2022). Damage and spatiotemporal dynamics of the Ngaio flat mite, Brevipalpus ferraguti (Trombidiformes: Tenuipalpidae), with observations on the development of the female insemination system. Experimental and Applied Acarology. 86(1):73-90. https://doi.org/10.1007/s10493-021-00670-y739086
Towards a Quantum Software Modeling Language
We set down the principles behind a modeling language for quantum software. We present a minimal set of extensions to the well-known Unified Modeling Language (UML) that allows it to effectively model quantum software. These extensions are separate and independent of UML as a whole. As such they can be used to extend any other software modeling language, or as a basis for a completely new language. We argue that these extensions are both necessary and sufficient to model, abstractly, any piece of quantum software. Finally, we provide a small set of examples that showcase the effectiveness of the extension set
Predictive Power Control for PV Plants With Energy Storage
This work presents a model predictive control (MPC) approach to manage in real-time the energy generated by a grid-tied photovoltaic (PV) power plant with energy storage (ES), optimizing its economic revenue. This MPC approach stands out because, when a long enough prediction horizon is used, the saturation of the ES system (ESS) can be advanced by means of a prediction model of the PV panels production. Therefore, the PV+ES power plant can modify its production so as to manage the power deviations with regard to that committed in the daily and intraday electricity markets, with the objective of reducing economic penalties. The initial power commitment is supposed in this work to be given by a higher level energy management operator. By a proper definition of its objective function, the predictive control allows us to economically optimize the PV+ES power plant performance. This control strategy is tested in simulations with actual data measured for different days with varying meteorological conditions. Results provide a good reference on the economic benefits which can be obtained thanks to the MPC introduction
Normas Internacionales de Auditoria : nálisisde las responsabilidades que tiene el auditor independiente en lo que respecta a las relaciones en una auditoria de estados financieros de acuerdo con la NIA 550
En el presente Seminario de Graduación se desarrollará un análisis de las responsabilidades del auditor independiente al efectuar una auditoría de estados financieros de conformidad a la
Norma Internacional de Auditoría 550 “partes vinculadas”, esta investigación resulta importante debido a que proporciona conocimientos acerca de procedimientos que se deben seguir al evaluar la razonabilidad de las transacciones en una auditoria de empresas que han realizado transacciones con partes relacionadas y determinar si los estados financieros presentan razonablemente sus cifras económicas, además se considera que es importante documentarse acerca del tema de partes vinculadas, ya que las leyes fiscales de nuestro país han tomado importancia acerca de la evaluación de las transacciones relacionadas. Asimismo, los resultados de esta investigación serán útil para los estudiantes de la carrera de ciencias económicas como guía a futuras investigaciones relacionadas con el tema abordado en este trabajo.
El presente trabajo investigativo se desarrolló en base a los objetivos planteados, para la consecución de cada uno de ellos fue necesario indagar en diferentes referencias bibliográficas entre ellos documentos de sitios web, normas, leyes y autores que aportan información valiosa para este seminario, con relación al caso práctico se planteará un encargo de auditoría entre una firma auditora “R&H Consulting” y la empresa “PROTECNO, S.A” quien realizó transacciones y relaciones con partes vinculadas, para lo cual el equipo de auditoría realizará los procedimientos necesarios, según la NIA 550, para analizar dichas transacciones y se reflejará el cumplimiento de las responsabilidades del auditor independiente y los principales papeles de trabajo como evidencia para el dictamen sobre la razonabilidad de las cifras de los estados financieros.
En el presente estudio investigativo se logran presentar conceptos que permiten identificar o diferenciar cuando existen o no transacciones con partes relacionadas, además de analizar las responsabilidades del auditor al evaluar transacciones con partes relacionadas y mostrar los principales papeles de trabajo que deben documentarse al realizar una auditoría de estados financieros de conformidad a la NIA 550 sobre partes vinculadas
Multibody Dynamics Model of a Human Hand for Haptics Interaction
In this paper we propose a strategy for modelling a human hand for Haptics interaction. The strategy consists in a parallel computing architecture that calculates the dynamics of a hand; this is accomplished by computing the dynamics of each finger in a parallel manner. In this approach multiple threads (e.g. haptics thread, graphics thread, collision detection thread, etc.) run concurrently and therefore we developed a synchronization mechanism for data exchange. We describe in detail the elements of the developed software
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