Contribution of wind farms to the stability of power systems with high penetration of renewables

This article belongs to the Special Issue Modeling and Control of Wind Energy Conversion Systems.Power system inertia is being reduced because of the increasing penetration of renewable energies, most of which use power electronic interfaces with the grid. This paper analyses the contribution of inertia emulation and droop control to the power system stability. Although inertia emulation may appear the best option to mitigate frequency disturbances, a thorough analysis of the shortcomings that face real-time implementations shows the opposite. Measurement noise and response delay for inertia emulation hinder controller performance, while the inherently fast droop response of electronic converters provides better frequency support. System stability, expressed in terms of rate of change of frequency (ROCOF) and frequency nadir, is therefore improved with droop control, compared to inertia emulation.This research was funded by the Spanish Ministry of Science, Innovation and Universities grant number PID2019-106028RB-I0

Anatomy and histochemistry of <i>Tarenaya hassleriana</i> (Cleomaceae), an interesting medicinal species

La decocción de la planta de Tarenaya hassleriana es utilizada en la región del Río de La Plata por sus propiedades como rubefaciente, digestiva, y antiescorbútica. El objetivo del estudio fue investigar caracteres de la hoja y tallo para identificar esta especie a partir de muestras enteras o fragmentadas. Se emplearon técnicas habituales de microscopia óptica y análisis histoquímico para identificar almidón, sustancias lipofílicas, fenólicas y mirosina. Los caracteres diagnósticos fueron: en la hoja, folíolos con venación eucamptódroma, con estomas anomocíticos presentes en ambas caras; tricomas glandulares uniseriados y pluriseriados, con cabezas unicelulares y pluricelulares conteniendo sustancias lipofílicas; mesofilo dorsiventral; en el tallo, la corteza primaria formada por varias capas de colénquima tangencial seguido de parénquima; el cilindro vascular secundario rodea la médula sólida, en cuyo parénquima se halló almidón, cristales poliédricos y esferocristales. Se detectaron idioblastos de mirosina en la epidermis y parénquimas de la hoja y el tallo. Los parámetros micrográficos descriptos garantizan una correcta identificación de T. hassleriana.Plant decoction of Tarenaya hassleriana is used as a traditional medicine in the Río de La Plata area. It has rubefacient, digestive, and antiscorbutic properties. The aim of this study was to investigate leaf and stem microcharacters to identify this species from whole or fragmented samples. The usual techniques of optical microscopy were employed. Histochemical tests for starch, lipophilic substances, phenolic substances, and mirosina were used. The main differential traits were: leaflets with eucamptodromous venation, amphistomatic with anomocytic stomata type; uniseriate and pluriseriate glandular trichomes, with unicellular and pluricellular heads containing lipophilic substances; dorsiventral mesophyll; stem with a primary cortex formed by tangential collenchyma followed by parenchyma; the secondary vascular cylinder surrounding the pith with starch, polyhedral microcrystals and spherocrystals. Idioblast of myrosin were detected in the epidermis and parenchyma of leaves and stems. The micrographic parameters described ensure a correct identification of T. hassleriana.Laboratorio de Morfología Comparada de Espermatófita

Fungosis del arándano (Vaccinium corymbosum L.) var. biloxi en el distrito de Jesús - Cajamarca

La investigación tuvo como objetivo determinar los fitopatógenos fungosos del arándano (Vaccinium corymbosum L.) var. biloxi en el distrito de Jesús – Cajamarca. Se determinaron:1) Alternaria sp., causando manchas foliares amorfas con halo clorótico y pigmentación púrpura violáceo, seguido de defoliación, con incidencia de 70 % y 30.37 % de severidad; 2) Botrytis cinerea Pers. Fr., ocasionó pudrición acuosa de flores, frutos y hojas, con 22 % de incidencia y 9.27 % de severidad; 3) Pestalotia sp., causante de antracnosis, distribuido en la corteza del tallo, ramas, brotes basales y apicales; las infecciones primero son de color rosado, anaranjado, conforme avanza la infección compromete el tejido cortical, se torna de color marrón oscuro, con 24.5 % de incidencia y 9.25 % de severidad; 4) Fusarium oxisporum Schl., patógeno causante de las necrosis en el tallo y ramas generalmente del tercio inferior, la necrosis son de color marrón rojizo primero y marrón oscuro después, con incidencia de 29 % y 12 % de severidad; 5) Cladosporium sp., causante de la necrosis en hojas y también prospera en frutos maduros que presentan daños por otros agentes, con incidencia de 71 % y severidad de 31.3 %; y 6) Fusarium sp., afecta durante el proceso de formación del callo y raíz en esquejes, con 15.5 % de incidencia y 9.59 % de severidad; dos aislamientos esporádicos de 7) Cephalosporium spp.; sobre las lesiones del chamso (Tomarus erichson)del orden coleóptero, ocasiona pudrición radicular, no se determinó la incidencia y severidad.Tesi

Animal welfare: the visitor effect on the behavior of five “Gorilla gorilla” individuals

Oral session 3[EN] Can the presence of visitors influence gorilla behavior? Tourists are an inevitable presence in zoos, so this study aimed to determine their impact on the behavior of the gorillas in the Parque de la Naturaleza de Cabárceno, as an indicator of their welfare. For this purpose, a comparative study of the behavior of 5 individuals was carried out, between the summer period when visitor numbers are high (277,082), and the winter period when there are fewer visitors (71,279)

The use of poplar and willow to produce biomass for energy

En esta revisión, se describen las principales características del uso de Salicáceas (álamos y sauces) en plantaciones de rotación corta para producir biomasa para energía. Se analizan distintos tipos de plantaciones para producir biomasa y la sustentabilidad de las mismas. Se resumen los resultados del mejoramiento de sauces y álamos para producir biomasa en distintos países. Finalmente, se discuten aspectos que será necesario investigar para el desarrollo de plantaciones de rotación corta con Salicáceas para producir biomasa en Argentina.In this revision, the characteristics of short rotation biomass plantations with Salicaceae (poplars and willows) are discussed. Different types of biomass plantations are described and their sustainability is discussed. The results obtained in breeding of poplar and willows for biomass production in different countries are summarized. Finally, there is a discussion of the research needed to develop short rotation bioenergy plantations in Argentina using Salicaceae.Facultad de Ciencias Agrarias y Forestale

A Review on the Degradation Implementation for the Operation of Battery Energy Storage Systems

A naive battery operation optimization attempts to maximize short-term profits. However, it has been shown that this approach does not optimize long-term profitability, as it neglects battery degradation. Since a battery can perform a limited number of cycles during its lifetime, it may be better to operate the battery only when profits are on the high side. Researchers have dealt with this issue using various strategies to restrain battery usage, reducing short-term benefits in exchange for an increase in long-term profits. Determining this operation restraint is a topic scarcely developed in the literature. It is common to arbitrarily quantify degradation impact into short-term operation, which has proven to have an extensive impact on long-term results. This paper carries out a critical review of different methods of degradation control for short-time operation. A classification of different practices found in the literature is presented. Strengths and weaknesses of each approach are pointed out, and future possible contributions to this topic are remarked upon. The most common methodology is implemented in a simulation for demonstration purposes.This research received no external funding.Publicad

Comparison of Two Energy Management System Strategies for Real-Time Operation of Isolated Hybrid Microgrids

The propagation of hybrid power systems (solar&#8211;diesel&#8211;battery) has led to the development of new energy management system (EMS) strategies for the effective management of all power generation technologies related to hybrid microgrids. This paper proposes two novel EMS strategies for isolated hybrid microgrids, highlighting their strengths and weaknesses using simulations. The proposed strategies are different from the EMS strategies reported thus far in the literature because the former enable the real-time operation of the hybrid microgrid, which always guarantees the correct operation of a microgrid. The priority EMS strategy works by assigning a priority order, while the optimal EMS strategy is based on an optimization criterion, which is set as the minimum marginal cost in this case. The results have been obtained using MATLAB/Simulink to verify and compare the effectiveness of the proposed strategies, through a dynamic microgrid model to simulate the conditions of a real-time operation. The differences in the EMS strategies as well as their individual strengths and weaknesses, are presented and discussed. The results show that the proposed EMS strategies can manage the system operation under different scenarios and help power system operator obtain the optimal operation schemes of the microgrid.This work was supported by the Autonomous Community of Madrid under the PROMINT-CM project (S2018/EMT-4366)

Rational Engineering of Multiple Active Sites in an Ester Hydrolase

Effects of altering the properties of an active site in an enzymatic homogeneous catalyst have been extensively reported. However, the possibility of increasing the number of such sites, as commonly done in heterogeneous catalytic materials, remains unexplored, particularly because those have to accommodate appropriate residues in specific configurations. This possibility was investigated by using a serine ester hydrolase as the target enzyme. By using the Protein Energy Landscape Exploration software, which maps ligand diffusion and binding, we found a potential binding pocket capable of holding an extra catalytic triad and oxyanion hole contacts. By introducing two mutations, this binding pocket became a catalytic site. Its substrate specificity, substrate preference, and catalytic activity were different from those of the native site of the wild type ester hydrolase and other hydrolases, due to the differences in the active site architecture. Converting the binding pocket into an extra catalytic active site was proven to be a successful approach to create a serine ester hydrolase with two functional reactive groups. Our results illustrate the accuracy and predictive nature of modern modeling techniques, opening novel catalytic opportunities coming from the presence of different catalytic environments in single enzymes

Multicamera Optical Tracker Assessment for Computer Aided Surgery Applications

Image-guided interventions enable the surgeon to display the position of instruments and devices with respect to the patient's imaging studies during surgery by means of a tracker device. Optical trackers are commonly chosen for many surgical applications when high accuracy and robustness are required. OptiTrack is a multicamera optical tracker whose number of sensors and their spatial configuration can be adapted to the application requirements, making it suitable for surgical settings. Nonetheless, no extensive studies of its accuracy are available. The purpose of this paper was to evaluate an eight-camera optical tracker in terms of accuracy, miscalibration sensitivity, camera occlusions, and tool detection in a feasible clinical setup. We studied the tracking accuracy of the system using a robotic arm (~μm precision) as the gold standard, a single reflective marker, and various tracked objects while the system was installed in an operating room. Miscalibration sensitivity was 0.16°. Mean target error was 0.24 mm for a single marker, decreasing to 0.05 mm for tracked tools. Single-marker error increased up to 1.65 mm when five cameras where occluded although 75% of the working volume showed an error lower than 0.23 mm. The accuracy was sufficient for navigating the collimator in intraoperative electron radiation therapy, improving redundancy and allowing large-working volumes. The tracker assessment we present and the validated miscalibration protocol are important contributions to image-guided surgery, where the choice of the tracker is critical and the knowledge of the accuracy in situations of camera occlusion is mandatory during surgical navigation

Plasticity of root growth and respiratory activity: Root responses to above-ground senescence, fruit removal or partial root pruning in soybean

This work focuses on the alterations in soybean root growth and activity during whole plant senescence and the contribution of roots to source-sink relations during plant development. The experiments were designed to analyze the activity of roots in relation to: a) whole plant senescence, b) total pod removal and c) root pruning (15, 25 and 50% of DW) during seed growth stages. Roots can grow until an advanced R5 stage and their specific activity decreases along the reproductive development but whole root activity declines from R6. However root respiration is maintained at a basal level until R8. Depodded plants showed a large increase of root dry matter (about 470%) and a large increase of AOX protein. Root pruning treatments showed a proportional increase of specific root respiration in 25 and 50% treatments but no differences of whole root respiration and dry matter partitioning at R7. These results indicate that roots are under the control of the requirements of above ground organs until final stages of seed growth but, after this, roots may survive independently for some time. This suggests that roots do not suffer a senescence-like process as leaves do. Also, plants have a high capacity to buffer changes in root biomass production and specific root activity under pod removal or partial root pruning.Instituto de Fisiología Vegeta