911 research outputs found
The Atmospheric Monitoring System of the JEM-EUSO Space Mission
An Atmospheric Monitoring System (AMS) is a mandatory and key device of a
space-based mission which aims to detect Ultra-High Energy Cosmic Rays (UHECR)
and Extremely-High Energy Cosmic Rays (EHECR) from Space. JEM-EUSO has a
dedicated atmospheric monitoring system that plays a fundamental role in our
understanding of the atmospheric conditions in the Field of View (FoV) of the
telescope. Our AMS consists of a very challenging space infrared camera and a
LIDAR device, that are being fully designed with space qualification to fulfil
the scientific requirements of this space mission. The AMS will provide
information of the cloud cover in the FoV of JEM-EUSO, as well as measurements
of the cloud top altitudes with an accuracy of 500 m and the optical depth
profile of the atmosphere transmittance in the direction of each air shower
with an accuracy of 0.15 degree and a resolution of 500 m. This will ensure
that the energy of the primary UHECR and the depth of maximum development of
the EAS ( Extensive Air Shower) are measured with an accuracy better than 30\%
primary energy and 120 depth of maximum development for EAS occurring
either in clear sky or with the EAS depth of maximum development above
optically thick cloud layers. Moreover a very novel radiometric retrieval
technique considering the LIDAR shots as calibration points, that seems to be
the most promising retrieval algorithm is under development to infer the Cloud
Top Height (CTH) of all kind of clouds, thick and thin clouds in the FoV of the
JEM-EUSO space telescope
Thin and thick cloud top height retrieval algorithm with the Infrared Camera and LIDAR of the JEM-EUSO Space Mission
The origin of cosmic rays have remained a mistery for more than a century.
JEM-EUSO is a pioneer space-based telescope that will be located at the
International Space Station (ISS) and its aim is to detect Ultra High Energy
Cosmic Rays (UHECR) and Extremely High Energy Cosmic Rays (EHECR) by observing
the atmosphere. Unlike ground-based telescopes, JEM-EUSO will observe from
upwards, and therefore, for a properly UHECR reconstruction under cloudy
conditions, a key element of JEM-EUSO is an Atmospheric Monitoring System
(AMS). This AMS consists of a space qualified bi-spectral Infrared Camera, that
will provide the cloud coverage and cloud top height in the JEM-EUSO Field of
View (FoV) and a LIDAR, that will measure the atmospheric optical depth in the
direction it has been shot. In this paper we will explain the effects of clouds
for the determination of the UHECR arrival direction. Moreover, since the cloud
top height retrieval is crucial to analyze the UHECR and EHECR events under
cloudy conditions, the retrieval algorithm that fulfills the technical
requierements of the Infrared Camera of JEM-EUSO to reconstruct the cloud top
height is presently reported.Comment: 5 pages, 6 figures, Atmohead Conference 201
Design and economic analysis of a hydrokinetic turbine for household applications
Social and political concerns on climate change have made renewable energy an essential component of government's work plans. Grid-connected horizontal-axis hydrokinetic turbines are promising eco-friendly power sources for electrical energy supply to households near middle-to-high discharge rivers, while providing an opportunity to sell the energy surplus. In this work, a rotor design analysis of a hydrokinetic turbine with a 1 m nominal radius is performed based on blade element momentum theory. Then, an economic analysis is presented in terms of the discounted payback period and the internal rate of return. The numerical results show that three-bladed hydrokinetic turbines with a nominal tip speed ratio of 5 and state-of-the art high lift-to-drag ratio hydrofoils (∼100) lead to maximum performance with a power coefficient around 0.45. Performance can be further improved in an affordable manner using diffuser-augmented hydrokinetic turbines. The use of hydrokinetic energy in household applications can be profitable in leading economic countries with a discounted payback period of 4-6 years. In energy developing countries, this technological solution can be cost effective accompanied by economic subsides and implementation of a local industry, resulting in similar payback periods.This work was supported by projects PID2019-106740RB-I00 and EIN2020-112247 of the Spanish Agencia Estatal de Investigación . Funding for APC: Universidad Carlos III de Madrid (Read & Publish Agreement CRUE-CSIC 2022)
Waste clay materials as pozzolanic additions
En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.-- 4 pages, 3 figures.The building materials industries have made
improvements in manufacturing processes. However,
with the implementation of quality systems, more
compliance, with new standard more restrictive, and
especially by the competition between products, it is
inevitable that industries deemed a rejection of
material unsuitable for marketing or materials waste.
The wastes from the ceramic industry (ceramic
waste) may have characteristics suitable for use as
pozzolanic materials, as it is known that the first
materials used as pozzolans were heat-treated clays,
material like clay products.This research was funded by a Science and
Technology Commission (CICYT) (Research Project
AMB96-1095).Peer reviewe
Downscaling ECMWF seasonal precipitation forecasts in Europe using the RCA model
6 páginas, 4 figuras.--Licencia Creative Commons Reconocimiento-No comercial 3.0The operational performance and usefulness of regional climate models at seasonal time scales are assessed by downscaling an ensemble of global seasonal forecasts. The Rossby Centre RCA regional model was applied to downscale a five-member ensemble from the ECMWF System3 global model in the European Atlantic domain for the period 1981–2001. One month lead time global and regional precipitation predictions were compared over Europe—and particularly over Spain—focusing the study in SON (autumn) dry events. A robust tercile-based probabilistic validation approach was applied to compare the forecasts from global and regional models, obtaining significant skill in both cases, but over a wider area for the later. Finally, we also analyse the performance of a mixed ensemble combining both forecasts.This work was partly supported by projects ENSEMBLES from the 6th FP EU(GOCE-CT-2003-505539), EXTREMBLES (CGL2010-21869) and CORWES (CGL2010-22158-C02) from the Spanish Ministry MICINN (Plan Nacional de I+D+i) and
by ESCENA (200800050084265) from the Spanish Ministry MARM.Peer reviewe
Stress-related anhedonia is associated with ventral striatum reactivity to reward and transdiagnostic psychiatric symptomatology
BACKGROUND: Early life stress (ELS) is consistently associated with increased risk for subsequent psychopathology. Individual differences in neural response to reward may confer vulnerability to stress-related psychopathology. Using data from the ongoing Duke Neurogenetics Study, the present study examined whether reward-related ventral striatum (VS) reactivity moderates the relationship between retrospectively reported ELS and anhedonic symptomatology. We further assessed whether individual differences in reward-related VS reactivity were associated with other depressive symptoms and problematic alcohol use via stress-related anhedonic symptoms and substance use-associated coping. METHOD: Blood oxygen level-dependent functional magnetic resonance imaging (fMRI) was collected while participants (n = 906) completed a card-guessing task, which robustly elicits VS reactivity. ELS, anhedonic symptoms, other depressive symptoms, coping behavior, and alcohol use behavior were assessed with self-report questionnaires. Linear regressions were run to examine whether VS reactivity moderated the relationship between ELS and anhedonic symptoms. Structural equation models examined whether this moderation was indirectly associated with other depression symptoms and problematic alcohol use through its association with anhedonia. RESULTS: Analyses of data from 820 participants passing quality control procedures revealed that the VS × ELS interaction was associated with anhedonic symptoms (p = 0.011). Moreover, structural equation models indirectly linked this interaction to non-anhedonic depression symptoms and problematic alcohol use through anhedonic symptoms and substance-related coping. CONCLUSIONS: These findings suggest that reduced VS reactivity to reward is associated with increased risk for anhedonia in individuals exposed to ELS. Such stress-related anhedonia is further associated with other depressive symptoms and problematic alcohol use through substance-related coping
The deterioration and environmental impact of binary cements containing thermally activated coal mining waste due to calcium leaching
Calcium-leaching processes can potentially degrade the structure of a concrete matrix. This problem is studied here through the progressive dissolution of Ca2+ in both ordinary Portland cement pastes (C-0) and binary cement blends (C-20) containing 20% thermally Activated Coal Mining Waste (ACMW).1 A series of accelerated tests are conducted that involve the immersion of these cement pastes in a 6 M ammonium nitrate solution at a temperature of 20 C for 7 and for 21 days. A rise in paste porosity was observed, due to increased capillary pore sizes of between 5 and 0.1 μm. In the case of the 20% ACMW pastes (C-20), calcium leaching decreased, probably as a consequence of the pozzolanic effect of the ACMW, while potassium and magnesium leaching increased, due to the presence of the phyllosilicates in the ACMW. The paste compounds most affected by leaching were Ca(OH)2, C6AS3H32, and C4AC¯H12. In general terms, it can be concluded that the incorporation of ACMW into binary cements slightly reduces the calcium leaching phenomena. Concerning the environmental impact assessment, the substitution of 20% OPC by ACMW reduced CO2 emissions by as much as 12% and improved energy efficiency by using approximately 19% fewer fossil resources.This research was developed in the framework of the MATCON Associated Unit (CSICTecnalia,
Madrid, Spain) with the support of the Spanish Ministry of Economy and
Competitiveness (Project Ref. MAT2012-37005-CO3-01/02/03) and the European
Regional Development Fund (MINECO/FEDER) (Project Ref.BIA2015-65558-C3-
1,2,3-R. The authors are also grateful to the Sociedad Anónima Hullera Vasco-Leonesa
and to the Spanish Cement Institute (IECA) for providing us with raw materials
Mineral phases in metakaolin-portlandite pastes cured 15 years at 60 °C. New data for scientific advancement
One of the problems addressed by the scientific community in connection with cement matrix hydration is the evolution of hydrated phases under certain, primarily temperature-related, curing conditions. Such conditions are of utmost importance when the cement generates metastable hydrated phases that develop into stable phases, inducing substantial physical-mechanical changes in the matrix. One such instance arises during the pozzolanic reaction between metakaolinite and calcium hydroxide at 60 °C when metastable hexagonal phases co-exist with cubic stable phases. Such processes are well understood in the short and medium term (<5 years). Evolution at longer curing times has not been studied, however. This paper describes the evolution of the initial (stable and metastable) mineral phases in the metakaolinite / Ca(OH) reaction toward a zeolite-like phase after 15 year curing at 60 °C. An understanding of such mineralogical changes is scientifically significant, given their direct impact on the engineering properties of cement-based matricesThe authors thank the Spanish Ministry of Science, Innovation and Universities and the European Regional Development Fund (ref: RTI2018-097074-B-C21/C22
HF spectrum activity prediction model based on HMM for cognitive radio applications
Although most of the research on Cognitive Radio is focused on communication bands above the HF upper limit (30 MHz), Cognitive Radio principles can also be applied to HF communications to make use of the extremely scarce spectrum more efficiently. In this work we consider legacy users as primary users since these users transmit without resorting to any smart procedure, and our stations using the HFDVL (HF Data+Voice Link) architecture as secondary users. Our goal is to enhance an efficient use of the HF band by detecting the presence of uncoordinated primary users and avoiding collisions with them while transmitting in different HF channels using our broad-band HF transceiver. A model of the primary user activity dynamics in the HF band is developed in this work to make short-term predictions of the sojourn time of a primary user in the band and avoid collisions. It is based on Hidden Markov Models (HMM) which are a powerful tool for modelling stochastic random processes and are trained with real measurements of the 14 MHz band. By using the proposed HMM based model, the prediction model achieves an average 10.3% prediction error rate with one minute-long channel knowledge but it can be reduced when this knowledge is extended: with the previous 8 min knowledge, an average 5.8% prediction error rate is achieved. These results suggest that the resulting activity model for the HF band could actually be used to predict primary users activity and included in a future HF cognitive radio based station
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