Analysis of the experimental spectral coherence in the Nysted Wind Farm

In this paper, it is analysed the coherence between wind speeds located in a horizontal plane corresponding to hub height of wind turbines in a large wind farm. The coherence is calculated through real data from Nysted Offshore Wind Farm. Concretely, the wind speed measured in the 72 Wind Turbines and in 2 of the meteorological masts during 9 months. The results are analysed in the scale of power fluctuations in large offshore wind farms. This analysis shows the needing of a new spectral coherence model.The work presented in this paper has been done in the research Project ”Power Fluctuations from large offshore wind farms” financed by the Danish Transmission System Operator Energinet.dk as PSO 2004 project number 6506. A. Vigueras-Rodr´ıguez is supported by the Spanish Ministerio de Educaci´on y Ciencia through the grant program “Becas FPU” and from the national research project “ENE2006-15422-C02-02

Multivariate linear regression versus symbolic regression from genetic programming. Application to the spectroscopic characterisation of urban wastewater

[EN] Characterising urban wastewater in real time is key to ensure the proper management of water resources and environmental protection. From indirect measurements, such as the molecular spectroscopy which provides information on the physicochemical properties of the water, it is possible to determine the pollutant load of wastewater from mathematical correlation models. The research compares multivariate linear regression models and symbolic regression models based on genetic programming to establish a correlation with the pollutant load of the wastewater. The study has focused on the comparison of models for the characterisation of total nitrogen, total phosphorus and nitrogen in the form of nitrate of 90 urban wastewater samples. It is observed that the symbolic regression based on genetic programming provides an improvement in goodness of fit (R2) of between 72.76% and 146.39% with respect to multivariate linear regression.[ES] Caracterizar en tiempo real las aguas residuales urbanas es clave para poder garantizar una correcta gestión de los recursos hídricos y la protección del medioambiente. A partir de mediciones indirectas, como la espectroscopía molecular que proporciona información sobre las propiedades físico-químicas del agua, es posible determinar la carga contaminante de las aguas residuales empleando modelos matemáticos de correlación. El presente trabajo compara la regresión lineal multivariable y los modelos de regresión simbólica basados en programación genética, para establecer una correlación con la carga contaminante de las aguas residuales. El estudio se ha centrado en la comparativa de modelos para la caracterización de nitrógeno total, fósforo total y nitrógeno en forma de nitrato, considerando 90 muestras de aguas residuales urbanas. Se observa que la regresión simbólica basada en programación genética proporciona una mejora en el ajuste (R2) de entre el 72.76% y 146.39% respecto a la regresión lineal multivariable.El primer autor agradece la financiación recibida de la Fundación Séneca-Agencia de Ciencia y Tecnología de la Región de Murcia (España), a través del programa de capacitación para nuevos investigadores en áreas específicas de interés para la industria y alta capacidad de transferencia de los resultados de investigación generados, titulado: “Subprograma Regional de Contratos de Formación de Personal Investigador en Universidades y OPIs” (Mod. B, Ref. 20320/FPI/17)”. El presente trabajo de investigación ha sido financiado mediante el proyecto MONITOCOES: New intelligent monitoring system for microorganisms and emerging contaminants in sewage networks. Referencia: RTC2019-007115-5, otorgado por el Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación, dentro de la convocatoria RETOS COLABORACIÓN 2019. El equipo desarrollado también ha recibido financiación para su industrialización a través del programa “Proof of Concept” de la Fundación Séneca, en el marco del proyecto “ Equipo de MONITORIZACIÓN en Tiempo REAl de Contaminantes en Aguas Residuales (MONITOREA).” (21662/PDC/21.).Carreres-Prieto, D.; García, JT.; Castillo, LG.; Carrillo, JM.; Vigueras-Rodriguez, A. (2022). Regresión lineal multivariable versus regresión simbólica a partir de programación genética. Aplicación a la caracterización espectroscópica de aguas residuales urbanas. Ingeniería del Agua. 26(4):261-277. https://doi.org/10.4995/ia.2022.1807326127726

Evaluation of Sulfide Control by Air-Injection in Sewer Force Mains: Field and Laboratory Study

Chemical and biological processes consume dissolved oxygen (DO) in urban wastewater during transportation along sewer systems. Anaerobic conditions (DO < 0.2 mg/L) are easily reached, leading to sulfide (S2−) generation. Release of free sulfide, hydrogen sulfide gas (H2S), from the liquid to the gaseous phase, causes odor, corrosion of pipes and supposes a risk for health of people working in sewers. These issues get worse in force mains, due to inability to take oxygen from the gaseous phase of pipe. Air injection is a suggested practice to control H2S emission in force mains. That technique aims to keep aerobic conditions in wastewater in order to avoid sulfide generation and favor a decrease of Biochemical Organic Demand (BOD). However, several force mains with air injection are not achieving their goals due to a limited oxygen transfer. Field measurements of dissolved oxygen in urban wastewater are presented in an existing force main with air injection during the summer of 2014 in the southeast of Spain. A laboratory scale model is constructed to quantify two-phase flow conditions in pipe due to air injection for different incoming flows rates of water and air. Particularly, for the case of plug flow, also known as elongated bubble flow. Velocity field measurement of water phase in laboratory allows estimating turbulent diffusivity of oxygen in the water, Em, and inter-phase mass transfer coefficient KL(T). In the laboratory, flow and air depth, bubble length, water velocity field, pressure inside force main and water and airflow rates are determined experimentally. These variables are used to assess DO in water phase of force main by comparison with those obtained from field measurements. This work allows assessing air injection efficiency in wastewater, and, therefore, to predict DO in wastewater in force mains

Urban Runoff Characteristics in Combined Sewer Overflows (CSOs): Analysis of Storm Events in Southeastern Spain

Storm water overflows have an important impact on the environment in many European countries. Nowadays, a better knowledge of combined sewer overflows (CSOs) pollution is required for implementing measures to reduce these emissions. In this work, pollution flows mobilized during rainy events have been monitored and modeled in two urban catchments located in the city of Murcia (southeast Spain). For each analyzed event, rainfall volume, in-sewer turbidity and water flow depth have been continuously measured. Therefore, sets of pollutographs and hydrographs have been obtained for each event analyzed. Characteristic variables have been defined and obtained for each event such as the maximum concentration of turbidity, the total event rainfall, the previous dry weather period, the time to the peak of the hydrograph and to the peak of the pollutograph, among others. Relations between variables have been adjusted through a statistical model. The adjusted parameters are used to generate pollutographs that are compared with those measured in field. The present work provides tools to assist in the knowledge of pollution transported through sewer network during stormy events, suggesting the creation of design pollutographs which may facilitate the evaluation of measures to reduce urban runoff pollution

Effectiveness of an educational group intervention in primary healthcare for continued exclusive breast-feeding: PROLACT study

Abstract Background The World Health Organization leads a global strategy to promote the initiation and maintenance of breast-feeding. Existing literature shows that education and supportive interventions, both for breast-feeding mothers as well as for healthcare professionals, can increase the proportion of women that use exclusive breast-feeding, however, more evidence is needed on the effectiveness of group interventions. Methods This study involves a community-based cluster randomised trial conducted at Primary Healthcare Centres in the Community of Madrid (Spain). The project aims to evaluate the effectiveness of an educational group intervention performed by primary healthcare professionals in increasing the proportion of mother-infant pairs using exclusive breastfeeding at six months compared to routine practice. The number of patients required will be 432 (216 in each arm). All mother-infant pairs using exclusive breastfeeding that seek care or information at healthcare centres will be included, as long as the infant is not older than four weeks, and the mother has used exclusive breastfeeding in the last 24 h and who gives consent to participate. The main response variable is mother-infant pairs using exclusive breast-feeding at six months. Main effectiveness will be analysed by comparing the proportion of mother-infant pairs using exclusive breast-feeding at six months between the intervention group and the control group. All statistical tests will be performed with intention-to-treat. The estimation will be adjusted using an explanatory logistic regression model. A survival analysis will be used to compare the two groups using the log-rank test to assess the effect of the intervention on the duration of breastfeeding. The control of potential confounding variables will be performed through the construction of Cox regression models. Discussion We must implement strategies with scientific evidence to improve the percentage of exclusive breast-feeding at six months in our environment as established by the WHO. Group education is an instrument used by professionals in Primary Care that favours the acquisition of skills and modification of already-acquired behaviour, all making it a potential method of choice to improve rates of exclusive breast-feeding in this period. Trial registration The trial was registered with ClinicalTrials.gov under code number NCT01869920 (Date of registration: June 3, 2013)