Power system stability analysis under increasing penetration of photovoltaic power plants with synchronous power controllers

The utilisation of renewable sources brings many benefits to electric power systems, but also some challenges such as the impact that renewable power plants employing power electronics have on the grid, which is gaining importance as the penetration of this type of generating stations increases, driven by the construction of large wind or solar photovoltaic (PV) power plants. This study analyses the impact of large-scale PV power plants on a transmission grid for different penetration levels. The analysis considers power plants formed by a number of power converters employing synchronous power controllers (SPCs), that allow them to have a harmonious interaction with the grid, and compares their performance with that of conventional power converter controllers, assuming in both cases that the power plants participate in frequency and voltage regulation. The study addresses both the small-signal stability of the system and its response to large disturbances that alter the active power balance and frequency stability. The results of the analysis show that PV power plants using SPCs are able to limit frequency deviations, improve the oscillation damping, and reduce the stress of other generating units, thus having a beneficial impact on the power system.Peer ReviewedPostprint (author's final draft

Diversidad e incidencia de hongos asociados a enfermedades foliares de la avena (Avena sativa L.) en los valles altos de México

El objetivo de este estudio fue determinar las especies de hongos asociados a enfermedades foliares de la avena en los Valles Altos de México. Durante los ciclos agrícolas primavera–verano 2009 y 2010, se recolectaron en 163 sitios diferentes un total de 815 muestras de plantas de avena exhibiendo síntomas de enfermedades foliares y signos en el caso de royas. La identificación de los hongos se basó en caracteres morfológicos. Se identificaron seis especies de hongos fitopatógenos: Colletotrichum graminicola, Curvularia hawaiiensis, Drechslera avenacea, Passalora graminis, Puccinia coronata y Puccinia graminis f. sp. avenae. Además, se encontraron cinco especies de hongos saprófitos o patógenos débiles: Alternaria triticicola, A. triticina, A. uredinis, Curvularia protuberata y Pleospora sp. Los hongos fitopatógenos que presentaron mayor frecuencia fueron: P. graminis f. sp. avenae (73%), P. coronata (61%) y D. avenacea (19%).The aim of this study was to determine the fungal species associated to foliar diseases on oat in the highlands of Mexico. During spring-fall seasons 2009 and 2010, a total of 815 samples of oat plants exhibiting foliar diseases were collected from 163 different oat fields. Fungal identification was based on morphological characteristics. Six different pathogenic fungal species were identified: Colletotrichum graminicola, Curvularia hawaiiensis, Drechslera avenacea, Passalora graminis, Puccina coronata, Puccinia graminis f. sp. avenae. Whereas, that the saprophytic and weakly pathogenic fungi founded were: Alternaria triticicola, A. triticina, A. uredinis, Curvularia protuberata y Pleospora sp. The species P. graminis f. sp. avenae (73%), P. coronata (61%) and D. avenacea (19%) were the pathogenic fungi most frequently founded.Gerencia de Comunicación e Imagen InstitucionalFil: García-León, E. Colegio de Postgraduados. Instituto de Fitosanidad. Fitopatología; MéxicoFil: Leyva-Mir, S.G. Universidad Autónoma Chapingo. Departamento de Parasitología Agrícola; México.Fil: Villaseñor-Mir, H.E. Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias. Campo Experimental del Valle de México; México.Fil: Rodríguez-García, M.F. Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias. Campo Experimental del Valle de México; México.Fil: Tovar-Pedraza, J.M. Colegio de Postgraduados. Instituto de Fitosanidad. Fitopatología; Méxic

The impact of irrigation on the quality of drainage water in a new irrigation district

[EN] The water quality of two agricultural drainage systems was monitored over two irrigation seasons in order to determine the sustainability of a new area of irrigated land (the Algerri-Balager irrigation district) located in the northeast of Spain. The average electrical conductivity of the drainage water was around 4dS·m-1, and the waters were enriched with boron, phosphorous and nitrate. Drainage represented 17% of total applied irrigation water (measured leached fraction) and is considered necessary to minimize the risk of soil salinization in semiarid environments. The most common ions in the drainage waters were magnesium, sulphate, and calcium and others related with dissolved soil minerals present in the area. The presence of Fe, Cu, Mn, Zn and pesticides was negligible. The information provided by this research was very useful for the irrigation district, and it’s transferable to other irrigation districts, as it could help to improve agricultural practices and be used to control the quality and quantity of irrigation drainage.[ES] La calidad del agua de dos sistemas de drenaje agrícola fue monitorizado en dos temporadas de riego para determinar la sostenibilidad de una zona recientemente transformada de secano a regadío y gestionada por la Comunidad de Regantes del Canal de Algerri-Balaguer, en el Noreste de España. La conductividad eléctrica media estuvo alrededor de los 4 dSm-1, y las aguas se enriquecieron con boro, fósforo y nitratos. El drenaje representó un 17% del total de agua de riego aplicada (fracción medida de lavado) y se considera necesario para minimizar el riesgo de salinización del suelo en ambientes semiáridos. Los iones más comunes presentes en las aguas de drenaje fueron el magnesio, el sulfato, y el calcio y otros relacionados con la disolución de minerales presentes en la zona de estudio. La presencia de Fe, Cu, Mg, Zn y fitosanitarios fue insignificante. La información que proporcionó el estudio fue muy interesante para la Comunidad de Regantes, y los aspectos metodológicos pueden ser aplicados en otras comunidades de regantes, ya que podría ayudar a mejorar las prácticas agrícolas y utilizarse para controlar la calidad y cantidad del agua de drenajeLos autores quieren agradecer al Sr. Antonio Enjuanes y al Sr. Joan Anglès (Departament d’Agricultura, Ramaderia, Pesca i Alimentació), al Sr. Francesc Mirada, presidente de la comunidad de regantes (en el momento de realizarse el trabajo de campo), al Sr. Antoni Costa presidente del sindicato de regantes de la Comunidad de Regantes, al Sr. Ramón Codina, técnico de la Comunidad de Regantes, y también a los estudiantes de la Universidad de Lleida que contribuyeron al primer año del proyecto (Sr. Xavier Farré y Sr. Albert Casals). Este trabajo ha sido financiado por el convenio de colaboración entre el Departament d’Agricultura, Ramaderia, Pesca i Alimentació de la Generalitat de Catalunya y la Universidad de Lleida (contratos C06027 y C08025)Villar Mir, J.; Pascual, M.; Rufat, J.; Villar, P. (2015). El impacto del riego en la calidad del agua de drenaje en una nueva zona regable. Ingeniería del Agua. 19(4):241-253. https://doi.org/10.4995/ia.2015.4113SWORD241253194Abrahao, R., Causapé, J., García-Garizábal, I., Merchán, D. (2011). Implementing irrigation: Salt and nitrate exported from the Lerma basin (Spain). Agricultural Water Management, 102(1), 105-112. doi:10.1016/j.agwat.2011.10.011Agència Catalana de l'Aigua. (2008). Water in Catalonia: diagnosis and proposed actions. Catalan Water Agency, Generalitat de Catalunya.Ascaso, E., Boixadera, J., Olarieta, J.R. (1991). Detailed Soil Survey Map of Catalonia of the irrigated area by Algerri-Balaguer Canal (La Noguera) (1:25000). Departament d'Agricultura, Alimentació i Acció Rural. Generalitat de Catalunya.Ayers, R.S., Westcot, D.W. (1985). Water quality for agriculture. FAO Irrig. Drain. Pap. 29 rev. 1; Food and Agricultura Organization of the United Nations, Rome.Barros, R., Isidoro, D., Aragüés, R. (2011). Long-term water balances in La Violada Irrigation District (Spain): II. Analysis of irrigation performance. Agricultural Water Management, 98(10), 1569-1576.California Department of Transportation (2011). Highway design manual. Chapter 850 Physical Standards. Disponible en http://www.dot.ca.gov/hq/oppd/hdm/pdf/english/chp0850.pdf (12 febrero 2014)Causapé, J. (2009a). Agro-environmental evaluation of irrigation land. I. Water use in Bardenas Irrigation District (Spain). Agricultural Water Management, 96(2), 179-187. doi:10.1016/j.agwat.2008.08.004Causapé, J. (2009b). Agro-environmental evaluation of irrigation land. II. Pollution induced by Bardenas Irrigation District (Spain). Agricultural Water Management, 96(2), 188-194.Directive 2000/60/EC of the European parliament and of the council of 23 October 2000 establishing a framework for Community action in the field of water policy. Official Journal of the European Communities L 327/1.Dougherty, T.C., Hall, A.W., Wallingford, H.R. (1995). Environmental impact assessment of irrigation and drainage projects. Irrigation and drainage paper 53, Food and Agriculture Organization of the United Nations, Rome.Durand, P., Neal, C., Lelong, F. (1992). Anthropogenic and natural contributions to the rainfall chemistry of a mountainous area in the Cevennes National Park (Mont-Lozere, southern France) Journal of Hydrology, 130, 71-85. doi:10.1016/0022-1694(92)90104-4EC Directive Relating to the Quality of Water Intended for Human Consumption 1982, 80/778/EEC, Office for Official Publications of the European Communities, 2 rue Mercier, L-2985 Luxembourg.Emmerich, W.E. (1990). Precipitation nutrient inputs in semiarid environments. Journal of Environmental Quality, 19(3), 621-624. doi:10.2134/jeq1990.00472425001900030044xEuropean Commission. (2005). Soil Atlas of Europe. European Soil Bureau Network. 128 pp.Fernández-Cirelli, A., Arumí, J.L., Rivera, D., Boochs, P.W. (2009). Environmental effects of irrigation in arid and semi-arid regions. Review. Chilean Journal of Agricultural Research, 69(supl. 1), 27-40.Gali, R.K., Soupi, M.L., Helmers, M.J. (2012). Electrical conductivity as a tool to estimate chemical properties of drainage water quality in the Des Moines Lobe, Iowa. Paper number 12-1338083. ASABAE conference Presentation. ASABAE Annual Int. Meeting, Dallas, Texas.Grattan, S.R. (2002). Irrigation water salinity and crop production. Water quality fact sheet. Division of Agriculture and Natural Resources. Pub. 8066. University of California.Grismer, M.E. (1993). Subsurface drainage system design and drain water quality. Journal of Irrigation and Drainage Engineering 119(3), 537-545. doi:10.1061/(ASCE)0733-9437(1993)119:3(537)Institute for European Environmental Policy (IEEE). (2000). The environmental impacts of irrigation in the European Union. A report to the Environment Directorate of the European Commission. Disponible en http://ec.europa.eu/environment/agriculture/pdf/irrigation.pdf (15 febrero2012)Instituto Nacional de Estadística. (2008). Water Statistics and Indicators. Boletín informativo del INE, Madrid.Isidoro, D., Quílez, D., Aragüés, R. (2004). Water balance and irrigation performance analysis: La Violada irrigation district (Spain) as a case study. Agricultural Water Management, 64(2), 123-142. doi:10.1016/S0378-3774(03)00196-3Isla, R., Aragüés, R., Royo, A. (2003). Spatial variability of salt-affected soils in the middle Ebro Valley (Spain) and implications in plant breeding for increase productivity. Euphytica, 134(3), 325-334. doi:10.1023/B:EUPH.0000004988.25257.91Kubáň, P., Reinhardt, M., Müller, B., Hauser. P. (2004). On-site simultaneous determination of anions and cations in drainage water using a flow injection-capillary electrophoresis system with contactless conductivity detection. Journal of Environmental Monitoring, 6, 169-174. doi:10.1039/b316422eLecina, S., Playán, E., Isidoro, D., Dechmim, F., Cuasapé, J., Faci, J.M. (2005). Irrigation evaluation and simulation at the irrigation district V of Bardenas (Spain). Agricultural Water Management, 73(3), 223-245. doi:10.1016/j.agwat.2004.10.007Leeden, van der F., Troise, F.L., Todd, D.K. (1990). The water encyclopaedia. Second Ed. Lewis Publishers, Inc., Chelsea, MI. Letey, J., Hoffman, G.F., Hopmans, J.W., Grattan, S.R., Suarez, D., Corwin, D.L., Oster, J.D., Wu, L., Amrhein, C. (2011). Evaluation of soil leaching requirement guidelines. Review. Agricultural Water Management, 98(4), 502-506. doi:10.1016/j.agwat.2010.08.009Litskas, V., Aschonitis, V.G., Antonopoulos, V.Z. (2010). Water quality in irrigation and drainage networks of Thessalonoki plain in Greece related to land use, water management, and agroecosystem production. Environmental Monitoring and Assessment, 163(1), 347-359. doi:10.1007/s10661-009-0839-3Lucha, P., Gutiérrez, F., Galve, J.P., Guerrero, J. (2012). Geomorphic and stratigraphic evidence of incision-induced halokinetic uplift and dissolution subsidence in transverse drainages crossing the evaporite-cored Barbastro-Balaguer Anticline (Ebro Basin, NE Spain). Geomorphology, 171-172, 154-172. doi:10.1016/j.geomorph.2012.05.015Organization for Economic and Co-operative Development (OECD). (1982). Eutrophication of Waters: Monitoring, assessment and control. Paris, France.Parris, K. (2011). Impact of agriculture on water pollution in OECD countries: recent trends and futures prospects. International Journal of Water Resources Development 27(1), 33-52. doi:10.1080/07900627.2010.531898Polo, M.J., Ordoñez, R., Giráldez, J.V., González, P. (1997). Aporte de nitrógeno efectuado por el agua de lluvia en el área de Córdoba. XV Congreso Nacional de Riegos. Lleida, Spain, Ed. Generalitat de Catalunya, 94-101.Rice, Ch.W., Havlin, J.L., Schepers, J.S. (1995). Rational nitrogen fertilization in intensive cropping systems. Fertilizer Research,42(1-3): 89-97. doi:10.1007/BF00750502Rodríguez-Ochoa, R., Olarieta, J.R., Castañeda, C. (2012). Micromorphology of salt accumulations in soils of north Monegros, Spain: Optical microscopy and SEM. R.M. Poch, M. Casamitjana, M.L. Francis (Eds). Proceedings of the 14th Int. Working Meeting on Soil Micromorphology, University of Lleida, Lleida, Spain, 31-35.Rowe, D., Abdel-Magid, I. (1995). Handbook of wastewater reclamation and reuse. Lewis Publishers, Boca Raton, FL.Stockle, C.O. (2001). Environmental impact of irrigation: a review. Disponible en http://www.swwrc.wsu.edu/newsletter/fall2001/irrimpact2.pdf (12 de enero de 2012).Verwey, P.M.J., Vermeulen, P.D. (2011). Influence of irrigation on the level, salinity and flow of groundwater at Vaalharts Irrigation scheme. Water SA, 37(2), 155-164. doi:10.4314/wsa.v37i2.65861Wriedt, G., Van der Velde, M., Aloe, A., Bouraoui, F. (2009). Estimating irrigation water requirements in Europe. Journal of Hydrology, 373(3-4), 527-544. doi:10.1016/j.jhydrol.2009.05.01

Significant effects in bread-making quality associated with the gene cluster Glu-D3/Gli-D1 from the bread wheat cultivar Prointa Guazú

Seed storage proteins (gliadins and glutenins) play a key role in the determination of dough and bread-making quality in bread wheat. This is due to the interaction between high and low molecular weight glutenins subunits and gliadins, via complex inter- and intramolecular bondings. In contrast to high molecular weight glutenins, low molecular weight glutenins and gliadins analysis is difficult due to the large number of expressed subunits and coding genes. For these reasons the role of individual proteins/subunits in the determination of wheat quality is less clear. In this work we studied the effect of gene clusters Glu-A3/Gli-A1 and Glu-D3/Gli-D1 in bread-making quality parameters using 20 F4-6 families from the cross Prointa Guazú × Prointa Oasis, both cultivars carrying identical high molecular weight glutenins subunits composition and presence of 1BL/1RS wheat-rye translocation, but differing in Glu-A3/Glu-D3 low molecular weight glutenins subunits and Gli-A1/Gli-D1 gliadins patterns. ANCOVA analysis showed a significant contribution of the Glu-D3/Gli-D1 gene cluster provided by Prointa Guazú to gluten strength explained by mixograph parameters MDS and PW, and Zeleny Test. Markers tagging Prointa Guazú Glu-D3/Gli-D1 alleles are available for strong gluten selection in breeding programs

Spatial and temporal variability of discards indicators and fishery factors affecting otter-trawl fishery in the spanish Mediterranean sea

A set of diversity indices were studied from data of observers on board two Mediterranean trawlers from 2001 to 2009. These diversity indices comprise relationships between total catch, landing and discard fractions to explore the accuracy of the estimates and to analyse the series trends using different methods, such as ARIMA. The hypothesis tested was that diversity indicators give a good representation of the changes produced in impacted bottom‐trawl areas, providing a reasonable fit of the data. ARIMA models are useful because they handle time-correlated modelling and forecasting. These techniques can also reveal changes in total catch as well changes in catch composition, probably induced by changes in effort fishery, seasonal (time) fluctuations, and environmental or climatic processes. Contrasted trends were also compared with survey data by MEDITS Mediterranean trawl survey time‐series indicator

Lack of clinical AIDS in SIV-infected sooty mangabeys with significant CD4+ T cell loss is associated with double-negative T cells

SIV infection of natural host species such as sooty mangabeys results in high viral replication without clinical signs of simian AIDS. Studying such infections is useful for identifying immunologic parameters that lead to AIDS in HIV-infected patients. Here we have demonstrated that acute, SIV-induced CD4+ T cell depletion in sooty mangabeys does not result in immune dysfunction and progression to simian AIDS and that a population of CD3 +CD4-CD8- T cells (double-negative T cells) partially compensates for CD4+ T cell function in these animals. Passaging plasma from an SIV-infected sooty mangabey with very few CD4 + T cells to SIV-negative animals resulted in rapid loss of CD4 + T cells. Nonetheless, all sooty mangabeys generated SIV-specific antibody and T cell responses and maintained normal levels of plasma lipopolysaccharide. Moreover, all CD4- low sooty mangabeys elicited a de novo immune response following influenza vaccination. Such preserved immune responses as well as the low levels of immune activation observed in these animals were associated with the presence of double-negative T cells capable of producing Th1, Th2, and Th17 cytokines. These studies indicate that SIV-infected sooty mangabeys do not appear to rely entirely on CD4+ T cells to maintain immunity and identify double-negative T cells as a potential subset of cells capable of performing CD4+ T cell-like helper functions upon SIV-induced CD4+ T cell depletion in this species

Central Pb+Pb Collisions at 158 A GeV/c Studied by Pion-Pion Interferometry

Two-particle correlations have been measured for identified negative pions from central 158 AGeV Pb+Pb collisions and fitted radii of about 7 fm in all dimensions have been obtained. A multi-dimensional study of the radii as a function of kT is presented, including a full correction for the resolution effects of the apparatus. The cross term Rout-long of the standard fit in the Longitudinally CoMoving System (LCMS) and the vl parameter of the generalised Yano-Koonin fit are compatible with 0, suggesting that the source undergoes a boost invariant expansion. The shapes of the correlation functions in Qinv and Qspace have been analyzed in detail. They are not Gaussian but better represented by exponentials. As a consequence, fitting Gaussians to these correlation functions may produce different radii depending on the acceptance of the experimental setup used for the measurement.Comment: 13 pages including 10 figure

Search for Disoriented Chiral Condensates in 158 AGeV Pb+Pb Collisions

The restoration of chiral symmetry and its subsequent breaking through a phase transition has been predicted to create regions of Disoriented Chiral Condensates (DCC). This phenomenon has been predicted to cause anomalous fluctuations in the relative production of charged and neutral pions in high-energy hadronic and nuclear collisions. The WA98 experiment has been used to measure charged and photon multiplicities in the central region of 158 AGeV Pb+Pb collisions at the CERN SPS. In a sample of 212646 events, no clear DCC signal can be distinguished. Using a simple DCC model, we have set a 90% C.L. upper limit on the maximum DCC production allowed by the data.Comment: 20 Pages, LaTeX, uses elsart.cls, 8 eps figures included, submitted to Physics Letters

Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV

A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lower limits on the masses of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81 GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the 95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure

Qualitative characteristics of meat from confined crossbred heifers fed with lipid sources

Lipids have been used in ruminant feed to replace high amounts of grain for increasing the diet energy density, performance and meat quality. This study evaluated the qualitative characteristics of meat from feedlot heifers fed with sources of lipid supplements. Twenty-one crossbred heifers (1/4Nelore × 1/4Santa Gertrudis × 1/2Braunvieh) were used. Each heifer received 60 % forage with a base of corn silage and 40 % concentrate, resulting in 5.8 % lipid content in the total diet. The following sources of lipids were used: soybeans, protected fat and soybean oil. There were no differences on physical characteristics of meat samples from heifers fed with the lipid sources. Soybeans increased the concentration of linoleic acid, content of polyunsaturated fatty acid and activity of the Δ9-desaturase C16 enzyme in the Longissimus muscle. The use of soybean oil in the diet increased the oleic acid, monounsaturated fatty acid, total cis- and trans-fatty acids (C18:0) and the activity of the Δ9-desaturase C16 enzyme in the subcutaneous fat. Diets with soybean grain had greater deposition of linoleic and linolenic acids than diets with fat protected and greater presence of these essential fatty acids are associated to a better composition and meat quality