Depth-based Outlier Detection for Grouped Smart Meters: a Functional Data Analysis Toolbox

Smart metering infrastructures collect data almost continuously in the form of fine-grained long time series. These massive time series often have common daily patterns that are repeated between similar days or seasons and shared between grouped meters. Within this context, we propose a method to highlight individuals with abnormal daily dependency patterns, which we term evolution outliers. To this end, we approach the problem from the standpoint of Functional Data Analysis (FDA), by treating each daily record as a function or curve. We then focus on the morphological aspects of the observed curves, such as daily magnitude, daily shape, derivatives, and inter-day evolution. The proposed method for evolution outliers relies on the concept of functional depth, which has been a cornerstone in the literature of FDA to build shape and magnitude outlier detection methods. In conjunction with our evolution outlier proposal, these methods provide an outlier detection toolbox for smart meter data that covers a wide palette of functional outliers classes. We illustrate the outlier identification ability of this toolbox using actual smart metering data corresponding to photovoltaic energy generation and circuit voltage records

Domain wall dynamics in expanding spaces

We study the effects on the dynamics of kinks due to expansions and contractions of the space. We show that the propagation velocity of the kink can be adiabatically tuned through slow expansions/contractions, while its width is given as a function of the velocity. We also analyze the case of fast expansions/contractions, where we are no longer on the adiabatic regime. In this case the kink moves more slowly after an expansion-contraction cycle as a consequence of loss of energy through radiation. All these effects are numerically studied in the nonlinear Klein-Gordon equations (both for the sine-Gordon and for the phi^4 potential), and they are also studied within the framework of the collective coordinate evolution equations for the width and the center of mass of the kink. These collective coordinate evolution equations are obtained with a procedure that allows us to consider even the case of large expansions/contractions.Comment: LaTeX, 18 pages, 2 figures, improved version to appear in Phys Rev

Association between breastfeeding duration and educational achievement in England: results from the Millennium Cohort Study

Objective: To evaluate the association between breastfeeding duration and educational outcomes at the end of secondary education among children from the Millennium Cohort Study. Design: Cohort study comparing school results at age 16 according to breastfeeding duration. Setting: England. Participants: Children born in 2000–2002 (nationally representative sample). Exposure: Self-reported breastfeeding duration (categorised). Main outcome measures: Standardised school assessments taken at the end of secondary education (General Certificate of Secondary Education (GCSEs), marked 9–1) in English and Mathematics, categorised as: ‘fail, marks <4’, ‘low pass, marks 4–6’ and ‘high pass, marks ≥7 (equivalent to A–A*)’. Additionally, overall achievement was measured using the ‘attainment 8’ score (adding the marks of eight GCSEs, English and Mathematics double weighted; 0–90). Results: Approximately 5000 children were included. Longer breastfeeding was associated with better educational outcomes. For example, after full adjustment for socioeconomic markers and maternal cognitive ability, in comparison with children who were never breastfed, those who were breastfed for longer were more likely to have a high pass in their English and Mathematics GCSEs, and less likely to fail the English GCSE (but not the Mathematics GCSE). Additionally, compared with those never breastfed, those breastfed for at least 4 months had, on average, a 2–3 point higher attainment 8 score (coefficients: 2.10, 95% CI 0.06 to 4.14 at 4–6 months; 2.56, 95% CI 0.65 to 4.47 at 6–12 months and 3.09, 95% CI 0.84 to 5.35 at ≥12 months). Conclusions: A longer breastfeeding duration was associated with modest improvements in educational outcomes at age 16, after controlling for important confounders

On the solution of strong nonlinear oscillators by applying a rational elliptic balance method

AbstractA rational elliptic balance method is introduced to obtain exact and approximate solutions of nonlinear oscillators by using Jacobi elliptic functions. To illustrate the applicability of the proposed rational elliptic forms in the solution of nonlinear oscillators, we first investigate the exact solution of the non-homogenous, undamped Duffing equation. Then, we introduce first and second order rational elliptic form solutions to obtain approximate solutions of two nonlinear oscillators. At the end of the paper, we compare the numerical integration values of the angular frequencies with approximate solution results, based on the proposed rational elliptic balance method

Aquebiología : estudios retrospectivos de la provincia de León : tiempos geológicos, primeras edades de la Historia

Con 12 fotograbados de fósiles y objetos recogidos por el autor.Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 201

Perturbaciones debidas a efluentes domésticos en poliquetos asociados a bancos de bivalvos de Brachidontes rodriguezii en Mar de Plata (Atlántico sudoccidental)

Continuous and short-term disturbances are produced on intertidal Brachidontes rodriguezii mussel beds by the sewage outfall of Mar del Plata, SW Atlantic. The effects on the associated polychaetes living on and between mussels were investigated, in both the spatial and short-term temporal scales. Multivariate methods show that the polychaete fauna was influenced by tidal level, total amount of sediment accumulated between mussels, distance from the sewage outfall, organic carbon of interstitial sediments, and sewage volume before and after the summer season. Environmental variables in the water column fitted with a spatial and temporal organic gradient. Capitella &lsquo;capitata&rsquo; sp. showed typical opportunistic behaviour in relation to organic enrichment, as did Neanthes succinea, both being numerically dominant near the sewage discharge. Cirratulus sp., Caulleriella alata, and Boccardia polybranchia were common at intermediate distances from the outfall. Syllis prolixa, S. gracilis, and Protoariciella uncinata reached their highest abundance at intermediate stations and were characteristic of the control site. Close to the outfall mussel density and dominance is low, and opportunist polychaetes successfully colonize organically enriched interstitial sediments. At intermediate distances from the outfall sediments retained by mussels reach their maximum values, and density of polychaetes is also high. The control station is characterized by monolayered mussel beds and very low diversity of polychaetes. Opportunistic polychaetes increase in response to short-term increases of sewage discharge during the summer season (November-March).Perturbaciones cont&iacute;nuas y de corto per&iacute;odo de tiempo debidas a efluentes dom&eacute;sticos afectan a los bancos de los bivalvos Brachidontes rodriguezii en Mar del Plata, Atl&aacute;ntico sudoccidental. Se investigaron sus efectos sobre los poliquetos que viven asociados dentro y sobre los bancos, tanto en la escala espacial como la temporal (corto plazo). M&eacute;todos multivariados mostraron que los poliquetos estuvieron relacionados al nivel de marea, al total de sedimentos acumulados entre los bivalvos, a la distancia al efluente, al carbono org&aacute;nico total de los sedimentos y al volumen de descarga antes y despu&eacute;s del verano. Las variables ambientales de la columna de agua estuvieron en concordancia con un gradiente de enriquecimiento org&aacute;nico espacial y temporal. Capitella &lsquo;capitata&rsquo; sp. mostr&oacute; el t&iacute;pico comportamiento oportunista en relaci&oacute;n al enriquecimiento org&aacute;nico, al igual que Neanthes succinea, siendo ambas especies num&eacute;ricamente dominantes cerca del efluente. Cirratulus sp., Caulleriella alata y Boccardia polybranchia fueron comunes a distancias intermedias del efluente. Syllis prolixa, S. gracilis y Protoariciella uncinata alcanzaron sus m&aacute;s altas abundancias a distancias intermedias, pero fueron caracter&iacute;sticas del sitio control. Cerca de la descarga del efluente la densidad y dominancia de bivalvos es baja, y los poliquetos oportunistas colonizaron exitosamente los sedimentos intersticiales enriquecidos org&aacute;nicamente. A distancias intermedias del efluente los sedimentos retenidos por los bivalvos alcanzaron sus mayores valores, y la riqueza de los poliquetos fue tambi&eacute;n alta. Las &aacute;reas control estuvieron caracterizadas por una monocapa de bivalvos y muy baja riqueza de poliquetos. Los poliquetos oportunistas incrementaron sus abundancias en respuesta al incremento del volumen de descarga en el per&iacute;odo antes-despu&eacute;s del verano (noviembre-marzo). &nbsp

Magnetization structure of a Bloch point singularity

Switching of magnetic vortex cores involves a topological transition characterized by the presence of a magnetization singularity, a point where the magnetization vanishes (Bloch point). We analytically derive the shape of the Bloch point that is an extremum of the free energy with exchange, dipole and the Landau terms for the determination of the local value of the magnetization modulus.Comment: 4 pages, 2 figure