657 research outputs found
Acid/base flow battery environmental and economic performance based on its potential service to renewables support
An innovative technology, called Acid Base Flow Battery (AB-FB), has been developed to overcome the intermittent supply of wind and solar electricity generation. It stores electrical energy using pH and salinity differences in the water and compared with other battery technologies, such as Vanadium Redox Flow Battery (VRFB), the new system is expected to be safer, more sustainable and to become a cost competitive option. To provide a deeper knowledge of the new system potentials, in this research, Life Cycle studies under cradle to grave approach have been carried out to assess the environmental and economic performance of 1 MW/6 MWh AB-FB system. Furthermore, 1 MW/6 MWh VRFB has been considered as the reference case. According to the comparative analysis, the AB-FB system exhibited the best environmental and economic performance, placing the AB-FB system as the most sustainable technology. In terms of environmental impacts related to the three process stages, the AB-FB system operation stage yielded the most relevant environmental burden, mostly attributed to energy losses due to the system efficiency. Manufacturing of the AB-FB system was the second stage with the more significant quote to the total environmental burden. Particularly, impacts were related to the power subsystem components being steel, copper, polyethylene and polyvinylchloride identified as the key materials responsible of this tendency. In contrast, the VRFB manufacturing was the most relevant process stage in terms of environmental implications. The energy subsystem was responsible for this tendency due to the vanadium-based electrolyte production related impacts. This component of the VRFB system was also its main constrains in terms of costs. The VRFB investment cost (339 €/kWh) was almost twice the AB-FB one (184 €/kWh), mostly affected by the VRFB electrolyte cost production
Evaluación del comportamiento mecánico de mezclas asfálticas templadas con 100 % de material reciclado
The use of Half Warm Mixes with high Reclaimed Asphalt content (HWMRA) has the potential to generate significant environmental advantages such as the reduction in consumption of natural resources and the emission of gases into the atmosphere. This paper therefore focuses on demonstrating the viability of using these types of mixes in wearing courses. For this purpose, an HWMRA with 70 % and 100 % Reclaimed Asphalt Pavement (RAP) and emulsion were designed in the laboratory. The performance of the mixes was then assessed and compared with that of conventional Hot Mix Asphalt. In a second stage, the mixes were manufactured in-plant, and laid and compacted in an Accelerated Pavement Test track. The cores were then extracted and tested for stiffness modulus and resistance to fatigue. The results from the tests conducted with both the laboratory specimens and the cores showed that the performance of HWMRA is comparable to that of HMA. These findings encourage greater confidence in promoting the use of these types of sustainable asphalt mixes.La utilización de mezclas asfálticas templadas con alto contenido de asfalto reciclado (HWMRA) conlleva ventajas medioambientales como la reducción del consumo de recursos naturales y la emisión de gases a la atmósfera. Este artículo se centra en mostrar la viabilidad de este tipo de mezclas para capas de rodadura. Para ello, se diseñaron mezclas HWMRA con 70 % y 100 % de asfalto reciclado en el laboratorio y se evaluó y comparó su comportamiento con una mezcla caliente convencional. En una segunda etapa, las mezclas fueron fabricadas en planta, extendidas y compactadas en una pista de ensayo acelerado de pavimentos. A continuación, se extrajeron testigos y se ensayaron para conocer su módulo de rigidez y resistencia a fatiga. Tanto los resultados de laboratorio como tras la fabricación en planta y puesta en obra mostraron que el comportamiento de mezclas HWMRA es comparable al de mezclas calientes convencionales. Dicha conclusión puede aportar confianza a este tipo de mezclas sostenibles promoviendo su mayor utilización
EL CLIMA DE LA CUENCA DEL RIO SEGURA (S.E. DE ESPANA): FACTORES QUE LO CONTROLAN
The termopluviometrical data of 65 meteorological stations located in the Basin of the Segura River (S.E. of Spain) have been used to characterize homogeneus climatic sectors. The statistical analysis of the information was carried out in different phases and on separate matrices.
To detect the possible effects of two different environmental factors (the altitude above the sea level and the proximity to the sea) on the basin climate, we have employed a step by step multiple linear regression analysis.
The results suggest the existence of termopluviometrical gradients where ten different climatic sectors can be identified. A few of these sectors seem to function as «islands».Se han empleado los datos termopluviométricos de 65 estaciones meteorológicas localizadas en la Cuenca del Segura (S.E. de España), para caracterizar sectores climáticos homogéneos en la misma. El análisis de la información se llevó a cabo en varias fases y sobre distintos tipos de matrices, aplicando técnicas estadísticas de ordenación.
Para detectar las posibles influencias que, sobre el clima de la cuenca, ejercen dos factores del medio físico: altitud y proximidad al mar, se aplicó un análisis de regresión lineal múltiple paso a paso («stepwise multiple linear regression»).
Los resultados obtenidos permiten definir diez tipos de sectores climáticos, a modo de gradientes termopluviométricos, donde destacan algunos que funcionan como «islas», de notable peculiaridad e interés ambiental
The VLT-FLAMES Tarantula Survey X: Evidence for a bimodal distribution of rotational velocities for the single early B-type stars
Aims: Projected rotational velocities (\vsini) have been estimated for 334
targets in the VLT-FLAMES Tarantula survey that do not manifest significant
radial velocity variations and are not supergiants. They have spectral types
from approximately O9.5 to B3. The estimates have been analysed to infer the
underlying rotational velocity distribution, which is critical for
understanding the evolution of massive stars.
Methods: Projected rotational velocities were deduced from the Fourier
transforms of spectral lines, with upper limits also being obtained from
profile fitting. For the narrower lined stars, metal and non-diffuse helium
lines were adopted, and for the broader lined stars, both non-diffuse and
diffuse helium lines; the estimates obtained using the different sets of lines
are in good agreement. The uncertainty in the mean estimates is typically 4%
for most targets. The iterative deconvolution procedure of Lucy has been used
to deduce the probability density distribution of the rotational velocities.
Results: Projected rotational velocities range up to approximately 450 \kms
and show a bi-modal structure. This is also present in the inferred rotational
velocity distribution with 25% of the sample having \ve100\,\kms
and the high velocity component having \ve\,\kms. There is no
evidence from the spatial and radial velocity distributions of the two
components that they represent either field and cluster populations or
different episodes of star formation. Be-type stars have also been identified.
Conclusions: The bi-modal rotational velocity distribution in our sample
resembles that found for late-B and early-A type stars. While magnetic braking
appears to be a possible mechanism for producing the low-velocity component, we
can not rule out alternative explanations.Comment: to be publisged in A&
On Optimal Coverage of a Tree with Multiple Robots
We study the algorithmic problem of optimally covering a tree with mobile
robots. The tree is known to all robots, and our goal is to assign a walk to
each robot in such a way that the union of these walks covers the whole tree.
We assume that the edges have the same length, and that traveling along an edge
takes a unit of time. Two objective functions are considered: the cover time
and the cover length. The cover time is the maximum time a robot needs to
finish its assigned walk and the cover length is the sum of the lengths of all
the walks. We also consider a variant in which the robots must rendezvous
periodically at the same vertex in at most a certain number of moves. We show
that the problem is different for the two cost functions. For the cover time
minimization problem, we prove that the problem is NP-hard when is part of
the input, regardless of whether periodic rendezvous are required or not. For
the cover length minimization problem, we show that it can be solved in
polynomial time when periodic rendezvous are not required, and it is NP-hard
otherwise
Comparison of different treatments used for polycystic ovary syndrome
Polycystic ovary syndrome (PCOS) is a disease that currently affects many women of reproductive age. In recent years, the incidence of PCOS has increased, affecting 4% of all women worldwide, with a prevalence of 6% in Mexico. PCOS is a condition characterized by different metabolic, reproductive and hormonal disorders such as hyperandrogenism, chronic anovulation, menorrhagia or infertility. Patients commonly develop clinical alterations such as hirsutism, acne and in some cases, they become overweight or obese. Different medications and therapeutic methods from different literatures were evaluated, both pharmacological such as inositol, metformin, resveratrol, simvastatin, dapagliflozin, which showed great improvement, decreasing the levels of hyperandrogenism in patients, as well as non-pharmacological, of which significant improvements were found with a change in lifestyle, such as exercise, ketogenic diet and herbal medications such as chamomile and cinnamon, which showed a positive change in patients. It is important to make a diffusion and early diagnosis of PCOS, since in this way it will be possible to have a timely treatment, which can be individualized according to the characteristics and needs of each patient
Metastable liquid lamellar structures in binary and ternary mixtures of Lennard-Jones fluids
We have carried out extensive equilibrium molecular dynamics (MD) simulations
to investigate the Liquid-Vapor coexistence in partially miscible binary and
ternary mixtures of Lennard-Jones (LJ) fluids. We have studied in detail the
time evolution of the density profiles and the interfacial properties in a
temperature region of the phase diagram where the condensed phase is demixed.
The composition of the mixtures are fixed, 50% for the binary mixture and
33.33% for the ternary mixture. The results of the simulations clearly indicate
that in the range of temperatures K, --in the scale of
argon-- the system evolves towards a metastable alternated liquid-liquid
lamellar state in coexistence with its vapor phase. These states can be
achieved if the initial configuration is fully disordered, that is, when the
particles of the fluids are randomly placed on the sites of an FCC crystal or
the system is completely mixed. As temperature decreases these states become
very well defined and more stables in time. We find that below K,
the alternated liquid-liquid lamellar state remains alive for 80 ns, in the
scale of argon, the longest simulation we have carried out. Nonetheless, we
believe that in this temperature region these states will be alive for even
much longer times.Comment: 18 Latex-RevTex pages including 12 encapsulated postscript figures.
Figures with better resolution available upon request. Accepted for
publication in Phys. Rev. E Dec. 1st issu
Reducing model bias in a deep learning classifier using domain adversarial neural networks in the MINERvA experiment
We present a simulation-based study using deep convolutional neural networks
(DCNNs) to identify neutrino interaction vertices in the MINERvA passive
targets region, and illustrate the application of domain adversarial neural
networks (DANNs) in this context. DANNs are designed to be trained in one
domain (simulated data) but tested in a second domain (physics data) and
utilize unlabeled data from the second domain so that during training only
features which are unable to discriminate between the domains are promoted.
MINERvA is a neutrino-nucleus scattering experiment using the NuMI beamline at
Fermilab. -dependent cross sections are an important part of the physics
program, and these measurements require vertex finding in complicated events.
To illustrate the impact of the DANN we used a modified set of simulation in
place of physics data during the training of the DANN and then used the label
of the modified simulation during the evaluation of the DANN. We find that deep
learning based methods offer significant advantages over our prior track-based
reconstruction for the task of vertex finding, and that DANNs are able to
improve the performance of deep networks by leveraging available unlabeled data
and by mitigating network performance degradation rooted in biases in the
physics models used for training.Comment: 41 page
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