3,744 research outputs found
Reverse engineering of biochar
This study underpins quantitative relationships that account for the combined effects that starting biomass and peak pyrolysis temperature have on physico-chemical properties of biochar. Meta-data was assembled from published data of diverse biochar samples (n = 102) to (i) obtain networks of intercorrelated properties and (ii) derive models that predict biochar properties. Assembled correlation networks provide a qualitative overview of the combinations of biochar properties likely to occur in a sample. Generalized Linear Models are constructed to account for situations of varying complexity, including: dependence of biochar properties on single or multiple predictor variables, where dependence on multiple variables can have additive and/or interactive effects; non-linear relation between the response and predictors; and non-Gaussian data distributions. The web-tool Biochar Engineering implements the derived models to maximize their utility and distribution. Provided examples illustrate the practical use of the networks, models and web-tool to engineer biochars with prescribed properties desirable for hypothetical scenarios
Visible and near-infrared observations of asteroid 2012 DA14 during its closest approach of February 15, 2013
Near-Earth asteroid 2012 DA14 made its closest approach on February 15, 2013,
when it passed at a distance of 27,700 km from the Earth's surface. It was the
first time an asteroid of moderate size was predicted to approach that close to
the Earth, becoming bright enough to permit a detailed study from ground-based
telescopes. Asteroid 2012 DA14 was poorly characterized before its closest
approach. We acquired data using several telescopes on four Spanish
observatories: the 10.4m Gran Telescopio Canarias (GTC) and the 3.6m Telescopio
Nazionale Galileo (TNG), both in the El Roque de los Muchachos Observatory
(ORM, La Palma); the 2.2m CAHA telescope, in the Calar Alto Observatory
(Almeria); the f/3 0.77m telescope in the La Hita Observatory (Toledo); and the
f/8 1.5m telescope in the Sierra Nevada Observatory (OSN, Granada). We obtained
visible and near-infrared color photometry, visible spectra and time-series
photometry. Visible spectra together with color photometry of 2012 DA14 show
that it can be classified as an L-type asteroid, a rare spectral type with a
composition similar to that of carbonaceous chondrites. The time-series
photometry provides a rotational period of 8.95 +- 0.08 hours after the closest
approach, and there are indications that the object suffered a spin-up during
this event. The large amplitude of the light curve suggests that the object is
very elongated and irregular, with an equivalent diameter of around 18m. We
obtain an absolute magnitude of H_R = 24.5 +- 0.2, corresponding to H_V = 25.0
+- 0.2. The GTC photometry also gives H_V = 25.29 +- 0.14. Both values agree
with the value listed at the Minor Planet Center shortly after discovery. From
the absolute photometry, together with some constraints on size and shape, we
compute a geometric albedo of p_V = 0.44 +- 0.20, which is slightly above the
range of albedos known for L-type asteroids (0.082 - 0.405).Comment: 7 pages, 4 figures, 1 table. Accepted in A&A (June 17 2013
Rendimientos productivos y calidad de la canal de hembras, machos castrados quirurgicamente y machos inmunocastrados procedentes de líneas paternas duroc y pietrain
Tradicionalmente la castración quirúrgica ha sido la práctica más habitual en la producción de cerdo blanco destinado a la industria de productos cárnicos curados. La castración quirúrgica conlleva un empeoramiento de los rendimientos productivos y penaliza el bienestar animal. Como alternativa ha surgido la inmunización de los cerdos contra el factor de liberación de la gonadotropina (GnRH) (Fàbrega et al., 2010). La inmunocastración suprime la función testicular (Zamaratskaia et al., 2008) y reduce la producción de androsterona (Dunshea et al., 2001) y escatol (Matthews et al., 2000) así como la agresividad (Jaros et al., 2005). Por tanto, la inmunocastración puede ser una alternativa a la castración física en situaciones comerciales. Por otro lado, para la obtención de productos curados se precisan canales con más grasa y mayor proporción de partes nobles que para productos frescos, por lo que se utilizan estrategias como aumentar el peso al sacrificio o el cruce con líneas paternas específicas. El objetivo de este estudio fue evaluar el rendimiento productivo y la calidad de la canal de hembras enteras (HE), machos castrados (MC) y machos inmunocastrados (MI) procedentes de genéticas paternas Duroc (DU) y Pietrain (PI) con un peso al sacrificio de 134 kg
Robust and Cooperative Image-Based Visual Servoing System Using a Redundant Architecture
The reliability and robustness of image-based visual servoing systems is still unsolved by the moment. In order to address this issue, a redundant and cooperative 2D visual servoing system based on the information provided by two cameras in eye-in-hand/eye-to-hand configurations is proposed. Its control law has been defined to assure that the whole system is stable if each subsystem is stable and to allow avoiding typical problems of image-based visual servoing systems like task singularities, features extraction errors, disappearance of image features, local minima, etc. Experimental results with an industrial robot manipulator based on Schunk modular motors to demonstrate the stability, performance and robustness of the proposed system are presented
Real-time detection of uncalibrated sensors using Neural Networks
Nowadays, sensors play a major role in several contexts like science,
industry and daily life which benefit of their use. However, the retrieved
information must be reliable. Anomalies in the behavior of sensors can give
rise to critical consequences such as ruining a scientific project or
jeopardizing the quality of the production in industrial production lines. One
of the more subtle kind of anomalies are uncalibrations. An uncalibration is
said to take place when the sensor is not adjusted or standardized by
calibration according to a ground truth value. In this work, an online
machine-learning based uncalibration detector for temperature, humidity and
pressure sensors was developed. This solution integrates an Artificial Neural
Network as main component which learns from the behavior of the sensors under
calibrated conditions. Then, after trained and deployed, it detects
uncalibrations once they take place. The obtained results show that the
proposed solution is able to detect uncalibrations for deviation values of 0.25
degrees, 1% RH and 1.5 Pa, respectively. This solution can be adapted to
different contexts by means of transfer learning, whose application allows for
the addition of new sensors, the deployment into new environments and the
retraining of the model with minimum amounts of data
Efecto de la densidad en cebo sobre el rendimiento productivo, la composición de la carne y el perfil de ácidos grasos de cerdos sacrificados con 110 kg de peso
El número de cerdos por cuadra y la densidad influyen sobre el rendimiento productivo
(Edmons et al., 1998). Además, la densidad de cría puede afectar a la calidad de la canal y
de la carne (Estevez et al., 2003), ya que una reducción del espacio disponible da lugar a
peleas y mordeduras de colas. Sin embargo, la producción de carne por m
2
aumenta con la
densidad con un mejor aprovechamiento de la superficie disponible. Por otro lado, la
densidad podría afectar de distinto modo a hembras (HE) y a machos castrados (MC)
debido posiblemente al menor consumo voluntario de pienso de las HE. A este particular,
Hamilton et al. (2003) observaron que a altas densidades de cría las HE fueron
relativamente más magras mientras que los MC eran relativamente más grasos. Cambios en
la densidad de cría, pueden afectar a la composición en ácidos grasos de la canal debido a
cambios en el consumo y a la utilización del alimento (Nürnberg et al., 1998). El objetivo de
este estudio fue comparar el efecto de la densidad de cebo de HE y MC con alto potencial
de crecimiento, sobre el rendimiento productivo y la composición de la carne y el perfil de
ácidos grasos en cerdos de 19 a 109 kg PV
- …