1,168 research outputs found
Analysis Of The Cyclability Of Lithium-polymer Batteries
Comunicación y póster en congresoLithium ion batteries and similar energy storage devices have an increasing importance for the modern society as they are present in many portable electronic devices and have perspectives in the fields of electric vehicles and renewable energy accumulation.
Herein, we present results from charge and discharge cycles on batteries under controlled conditions. The cyclability of commercial lithium-polymer pouch batteries under different charge/discharge rates and temperatures was studied. Based on the results, the relationship between the state of charge and the cell voltage was obtained, as well as degradation of the cells, i.e., the decrease of the energy capacity after a number of cycles.
The experimental results were compared with simulations based on Newman's model for Lithium Ion Batteries, carried out using the COMSOL Multiphysics® software. The batteries and fuel cell and the heat transfer modules were use to couple between the temperature and the electrochemical interactions. The results show the correlation between temperature, C-rate and degradation in lithium ion batteries. It is specially remarkable the decrease of the apparent capacity of batteries at low temperatures, and the increase of the degradation at higher temperatures. These results are essential for the design of mechanisms that could prevent battery failure.The authors acknowledge the financial support from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045, and the "Plan Propio de Investigación y Transferencia de la Universidad de Málaga", code: PPIT.UMA.B5.2018/17
Optical Absorption by Indirect Excitons in a Transition Metal Dichalcogenide Double Layer
We calculate the binding energy, transition energies, oscillator strength,
and absorption coefficient of indirect excitons in transition metal
dichalcogenide (TMDC) double layers separated by an integer number of hexagonal
boron nitride (h-BN) monolayers. The absorption factor, a dimensionless
quantity which gives the fraction of incoming photons absorbed by the indirect
excitons in the double layer, is evaluated. The aforementioned optical
quantities are obtained for transitions from the ground state to the first two
excited states. All quantities are studied as a function of the interlayer
separation, which may be experimentally controlled by varying the number of
h-BN monolayers between the TMDC layers. Calculations are performed by using
the exciton wave function and eigenenergies obtained for the Keldysh potential.
For each material, we choose a combination of the exciton reduced mass and the
dielectric screening length from the existing literature which give the largest
and the smallest indirect exciton binding energy. These combinations of
material parameters provide upper and lower bounds on all quantities presented.
Our findings can be examined experimentally via two-photon spectroscopy.Comment: 13 pages, 3 figure
Data assimilation of stratospheric constituents: a review
International audienceThe data assimilation of stratospheric constituents is reviewed. The data assimilation method is introduced, with particular consideration to its application to stratospheric constituent measurements. Differences from meteorological data assimilation are outlined. Historically, two approaches have been used to carry out constituent assimilation. One approach has carried constituent assimilation out as part of a numerical weather prediction system; the other has carried it out in a standalone chemical model, often with a more sophisticated representation of chemical processes. Whereas the aim of the numerical weather prediction approach has been to improve weather forecasts, the aims of the chemical model approach have included providing chemical forecasts and analyses of chemical constituents. A range of constituent assimilation systems developed in these two areas is presented and strengths and weaknesses discussed. The use of stratospheric constituent data assimilation to evaluate models, observations and analyses, and to provide analyses of constituents, monitor ozone, and make ozone forecasts is discussed. Finally, the current state of affairs is assessed, future directions are discussed, and potential key drivers identified
Human immunodeficiency virus type 1 recombinant B/G subtypes circulating in Coimbra, Portugal.
An increasing prevalence of HIV-1 non-B variants is being noticed in several European regions, particularly in countries such as Portugal, which have closer contacts with African endemic areas, where multiple HIV subtypes cocirculate. HIV-1 subtyping by phylogenetic analyses of reverse transcriptase, protease and env (C2-V3) genomic regions was carried out in plasma collected from 18 HIV-1-infected subjects living in Coimbra, Portugal, and suspected to be infected with non-B variants. Three (16.7%) subjects carried recombinant B/G viruses (BV3/BRT/Gpro; GV3/URT/Bpro; AV3/GRT/Bpro), whereas all the remaining individuals were infected with HIV-1 subtype B. This is the first report of recombinant B/G subtypes in Portugal
Phase estimation with limited coherence
We investigate the ultimate precision limits for quantum phase estimation in
terms of the coherence, , of the probe. For pure states, we give the minimum
estimation variance attainable, , and the optimal state, in the
asymptotic limit when the probe system size, , is large. We prove that pure
states are optimal only if scales as with a sufficiently large
proportionality factor, and that the rank of the optimal state increases with
decreasing , eventually becoming full-rank. We show that the variance
exhibits a Heisenberg-like scaling, , where decreases
to as increases, leading to a dimension-independent relation.Comment: 10 pages, 5 figure
Dry cured low-fat rabbit sausage: A much healthier disruptive food that enhances rabbit meat consumption
The main objective of this research was to develop a fuet from rabbit meat with reduced fat and salt content to encourage rabbit consumption and to find out consumer preference for this innovative food compared to retail fuet. Two products were designed: F5, containing fat and F4, where fatty tissue was substituted by konjac gum. In both, salt was partially substituted by KCl. These products, in comparison to commercial ones (pork, chicken and turkey), showed a reduction of at least 40% in the total energy value while protein raised on average 57.81% because of the lower fat content of rabbit and konjac gum use. In addition, there was a decrease in the salt content of approximately 19.50%. The above represents a huge competitive advantage for these new products from a nutritional point of view. The rabbit fuets were characterised by a spicy taste, slightly sour smell, and succulence, lower than in commercial fuets. It could be concluded that the rabbit fuet had a higher protein and lower fat and salt content than commercial fuets. However, they were less juicy and less succulent and therefore consumers preferred the commercial ones. The use of konjac gum does not seem to have any effect on this type of cured product
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