514 research outputs found
The Mercedes water Cherenkov detector
The concept of a small, single-layer water
Cherenkov detector,with three photomultiplier tubes (PMTs),
placed at its bottom in a 120◦ star configuration (Mercedes
Water Cherenkov Detector) is presented. The PMTs are
placed near the lateral walls of the stations with an adjustable
inclination and may be installed inside or outside the water
volume. To illustrate the technical viability of this concept
and obtain a first-order estimation of its cost, an engineering
designwas elaborated. The sensitivity of these stations to low
energy Extensive Air Shower (EAS) electrons, photons and
muons is discussed, both in compact and sparse array configurations.
It is shown that the analysis of the intensity and time
patterns of the PMT signals, using machine learning techniques,
enables the tagging of muons, achieving an excellent
gamma/hadron discrimination for TeV showers. This concept
minimises the station production and maintenance costs,
allowing for a highly flexible and fast installation. Mercedes
Water Cherenkov Detectors (WCDs) are thus well-suited for
use in high-altitude large gamma-ray observatories covering
an extended energy range from the low energies, closing the
gap between satellite and ground-based measurements, to
very high energy regions, beyond the PeV scale.Portuguese Foundation for Science and Technology PTDC/FISPAR/4300/2020
DL57/2016/cP1330/cT0002MEYS of the Czech Republic LTT 20002Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio De Janeiro (FAPERJ) 211.342/2021Portuguese Foundation for Science and TechnologyEuropean Commission PRT/BD/151553/202
Efficient Parallel Feature Selection for Steganography Problems
The steganography problem consists of the identification of
images hiding a secret message, which cannot be seen by visual inspection.
This problem is nowadays becoming more and more important since
the World Wide Web contains a large amount of images, which may be
carrying a secret message. Therefore, the task is to design a classifier,
which is able to separate the genuine images from the non-genuine ones.
However, the main obstacle is that there is a large number of variables
extracted from each image and the high dimensionality makes the feature
selection mandatory in order to design an accurate classifier. This paper
presents a new efficient parallel feature selection algorithm based on the
Forward-Backward Selection algorithm. The results will show how the
parallel implementation allows to obtain better subsets of features that
allow the classifiers to be more accurate.TIN2007-60587, P07-TIC-02768 and P07-TIC-02906,TIC-3928Nokia Foundation,
Finlan
Tackling the muon identification in water Cherenkov detectors problem for the future Southern Wide-field Gamma-ray Observatory by means of Machine Learning
We would like to thank to A. Bueno for all the support and useful discussions during the development of this work. The authors thank also for the financial support by OE - Portugal, FCT, I. P., under project PTDC/FIS-PAR/29158/2017. R. C. is grateful for the financial support by OE-Portugal, FCT, I. P., under DL57 /2016/cP1330/cT0002. A. G. is grateful for the financial support by the projects MINECO FPA2017-85197-P and PID2019-104676GB-C32. B.S.G. is grateful for the financial support by grant LIP/BI - 14/2020, under project IC&DT, POCI-01-0145-FEDER-029158.This paper presents several approaches to deal with the problem of identifying muons in a water Cherenkov detector with a reduced water volume and 4 PMTs. Different perspectives of information representation are used, and new features are engineered using the specific domain knowledge. As results show, these new features, in combination with the convolutional layers, are able to achieve a good performance avoiding overfitting and being able to generalise properly for the test set. The results also prove that the combination of state-of-the-art machine learning analysis techniques and water Cherenkov detectors with low water depth can be used to efficiently identify muons, which may lead to huge investment savings due to the reduction of the amount of water needed at high altitudes. This achievement can be used in further research to be able to discriminate between gamma and hadron-induced showers using muons as discriminant.OE - Portugal, FCT, I. P. PTDC/FIS-PAR/29158/2017
DL57 /2016/cP1330/cT0002Spanish Government FPA2017-85197-P
PID2019-104676GB-C32
LIP/BI - 14/2020
POCI-01-0145-FEDER-02915
Mutual Information Based Initialization of Forward-Backward Search for Feature Selection in Regression Problems
Pure feature selection, where variables are chosen or not to
be in the training data set, still remains as an unsolved problem, especially
when the dimensionality is high. Recently, the Forward-Backward
Search algorithm using the Delta Test to evaluate a possible solution was
presented, showing a good performance. However, due to the locality of
the search procedure, the initial starting point of the search becomes crucial
in order to obtain good results. This paper presents new heuristics to
find a more adequate starting point that could lead to a better solution.
The heuristic is based on the sorting of the variables using the Mutual
Information criterion, and then performing parallel local searches. These
local searches provide an initial starting point for the actual parallel
Forward-Backward algorithm
Optimal experimental design (OED) for the growth rate of microbial populations. Are they really more “optimal” than uniform designs?
Secondary growth models from predictive microbiology can describe how the growth rate of microbial populations varies with environmental conditions. Because these models are built based on time and resource consuming experiments, model-based Optimal Experimental Design (OED) can be of interest to reduce the experimental load. In this study, we identify optimal experimental designs for two common models (full Ratkowsky and Cardinal Parameters Model (CPM)) for a different number of experiments (10–30). Calculations are also done fixing one or more model parameters, observing that this decision strongly affects the layout of the OED. Using in silico experiments, we conclude that OEDs are more informative than conventional (equidistant) designs with the same number of experiments. However, OEDs cluster the experiments near the growth limits (Xmin and Xmax) resulting in impractical designs with aggregated experimental runs ~10 times longer than conventional designs. To mitigate this, we propose a novel optimality criterion (i.e., the objective function) that accounts for the aggregated time. The novel criterion provides a reduction in parameter uncertainty with respect to the conventional design, without an increase in the experimental load. These results underline that an OED is only based on information theory (Fisher information), so the results can be impractical when actual experimental limitations are considered. The study also emphasizes that most OED schemes identify where to measure, but do not give an indication on how many experiments should be made. In this sense, numerical simulations can estimate the parameter uncertainty that would be obtained for a particular experimental design (OED or not). These results and methodologies (available in Open Code) can guide the design of future experiments for the development of secondary growth models
Simulation of the dynamics of a drug in farm animals
This study aims to simulate the behavior of a drug in farm animals, for which limited data is available. The drug is provided in the food for the animals, but only experimental data related to food intake over time for a set of pigs in a farm is available for the design of the simulation model. The main purpose of this study is to increase the understanding of the process of intake and absorption of drug in farm animals and to establish a framework that could be used in future applications addressing how to design farms in a more intelligent way or how to supply the necessary amount of drug that is efficiently protecting all the animals from disease while costs are minimized. This study is part of a research project conducted by researchers at the Veterinarian Faculty of the Universitat Autonoma of Barcelona (UAB) and that is expected to be published in several scientific journals
Variaciones espacio-temporales en la composición y/o abundancia de Hongos Micorrízicos Arbusculares (HMA) en táxones vegetales de interés para la reconstrucción dunar
Successful arbuscular mycorrhizal fungi (AMF) symbiosis in sand dunes is a key factor for the maintenance of stable vegetation. Therefore, the main goal of this work was to study the AMF species associated with sand dunes in the Gulf of Valencia (Spain), as well as the effects of environmental and temporal factors on these AMF communities. In order to achieve these, soil samples from the rhizosphere of four plant species were seasonally collected at 6 sites during 2 years in three habitats. Frequency and relative abundance of AMF among these samples were examined. Among the ten AMF species identified, only Corymbiglomus corymbiforme and Diversispora aurantia (Diversisporaceae) had been previously described. Populations of these species in these sandy ecosystems displayed higher morphological variability than those originally described having the same macro- and micro-structure of spores. Moreover, regarding the other eight species, D. valentina (Diversisporaceae), Cetraspora sucrosa, Racocetra papillosa and R. sicanica (Gigasporaceae) displayed a phylogenetically unknown position, although all were related to some species of their respective genus. In respect to Scutellospora deformata (Gigasporaceae), it was molecularly related with a strain of Sc. calospora (GenBank FJ461865.1), however, it was less related with the type material of this species (GenBank AJ510231.1). Consequently, we suggest that material of this strain (GenBank FJ461865.1) should be revised. On the other hand, Funneliformis pillosus (Glomeraceae) was related, morphological and molecularly, to F. coronatus. Glomus ibericum (Glomeraceae) was related morphological and molecularly with G. aggregatum and G. macrocarpum. Finally, Septoglomus mediterraneum (Glomeraceae) was molecularly related with S. jasnowskae and morphologically related to S. turnauae, S. constrictum, S. furcatum and S. titan. Furthermore, pure cultures of F. pillosus, S. mediterraneum, Co. corymbiforme, D. aurantia and D. valentina were obtained at the greenhouse. Overall, the distribution of all AMF species found was mainly correlated to the anthropogenic disturbance of the site. Meanwhile, Gigasporaceae C. sucrosa and R. sicanica preferred undisturbed soil; Diversisporaceae, Glomeraceae and the others Gigasporaceae identified were associated to recently restored sand dunes. Although all AMF species were found in all plant species analyzed, interestingly, Co. corymbiforme was mainly associated to Echinophora spinosa. Our results might contribute to improve Mediterranean sand dunes restoration
Control selectivo por visión artificial del brazo Robotnik
La intención directa del presente proyecto es la de adquirir conocimientos de manera autónoma sobre materias de robótica y visión artificial, materias que no se imparten como tales en el itinerario de un graduado en G.I.T.I. y que siempre me han llamado la atención e interesado. Esto culminaría con la realización de una aplicación práctica que coordine las diferentes técnicas estudiadas.
Se pretende obtener la solución de un problema real en que el papel de la visión sea tanto selectivo como extractivo y de control. Selectivo porque se desea que el robot elija según el color el objetivo sobre el que realizar alguna acción en lo que se llama procesamiento de imágenes. Extractivo porque la posición del objeto en la imagen permitirá obtener ciertos parámetros con los que el robot realizará debidamente la acción para la cual ha sido programado. La aplicación también incluirá una parte de control de movimiento de los motores. Tanto el proceso de definición de los objetivos como el de la aplicación a desarrollar han sido extensamente deliberados para conseguir un equilibrio entre practicidad y dificultad. Finalmente, se decidió que la aplicación del brazo robótico consistiera en la extracción de objetos de un color determinado (selectivo) en movimiento en una cinta transportadora. En esta aplicación solo sería necesario el uso de tres de los seis grados de libertad disponibles, aquellos que permiten la disposición del extremo en cualquier posición y orientación en el plano de actuación del robot (plano vertical). Además, la limitación de grados de libertad en el movimiento del objeto que supone el desplazamiento rectilíneo permite el control con una única cámara que extraiga los parámetros necesarios para realizar la captura. La cinta transportadora fue simulada con una guía situada en una mesa métrica para limitar el movimiento a uno rectilíneo. Se pretendió que ofreciera la menor resistencia al avance para poder simular lo mejor posible velocidad constante.Escuela Técnica Superior de Ingeniería IndustrialUniversidad Politécnica de Cartagen
Desarrollo de sistema de medida del consumo de energía para la tarjeta BeagleBoard
En la actualidad existen cada vez más dispositivos móviles que utilizamos diariamente. Estos dispositivos usan las nuevas tecnologías inalámbricas, ya sean redes de telefonía, Wifi o Bluetooth, lo que conlleva un consumo de energía elevado. Estos dispositivos además tienen una limitación que es la capacidad de la batería. Un ejemplo claro son los smartphones, los usamos a diario y la batería
dura un día o poco más.
Dada esta problemática del alto consumo de energía el mundo de la electrónica de consumo se ve obligado a desarrollar aplicaciones y sistemas operativos que realicen un consumo de potencia más eficientes, baterías de otro tipo de
composiciones, etc. Para lo que es necesario que exista una forma eficaz de medir el consumo de energía.
En la actualidad, en el laboratorio del GDEM (Grupo de Diseño Electrónico y Microeletrónico) existen varias corrientes de acción a la hora de resolver o paliar
esta problemática. Aquí podemos dividirlo en dos grupos: trabajos que se dediquen a conseguir que el sistema realice un consumo más eficiente de la energía y trabajos dedicados a realizar medidas más precisas de este consumo para que, a su vez, sean utilizadas por el propio sistema para decidir formas de actuar.
Con estas motivaciones se ha diseñado una tarjeta capaz de medir la potencia consumida por la BeagleBoard usando un método de medida novedoso. Los resultados obtenidos validan el diseño y el presupuesto total de la fabricación ha
sido inferior a diez euros.
Por lo tanto, los objetivos se han cumplido fabricando una tarjeta caracterizada por su sencillez y su bajo coste, además de abrir la puerta a que, junto con un trabajo futuro, se consiga que la BeagleBoard sea capaz de conocer el consumo de potencia en tiempo real.
ABSTRACT.
At present, the number of mobile devices that we use normally are increasing.
These devices use the new wireless technologies, whether telephone network, wireless or Bluetooth, which carries a large power consumption. These devices also have a limitation which is the battery capacity. One clear example is the smartphones, we use them daily and the battery is spent in a day.
With this problem of high energy consumption the world of consumer electronics is forced to develop applications and operating systems with more efficient power consumption or a battery of other compositions. For that purposese it is
necessary to have an effective way to measure energy consumption.
In the GDEM (Microelectronic and Electronic Design Group) lab there are several streams action for solving or alleviating this problem. Here we can divide into two groups: jobs that are dedicated to getting the system that perform more efficient consumption of energy and works dedicated to doing more precise measures of this consumption.
With these motivations we designed a board which was able to measure the power consumed by the BeagleBoard using a innovative measurement method.
The results validate the design and the price of the board is less than 10 euros.
Therefore, the goals have been accomplished by making a board which is characterized by its simplicity and low cost. It has also opened the door to, in a future work, the BeagleBoard be able to know the power consumption in real
time by adding the necessary software
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