3,521 research outputs found
Addicions a la flora algològica del Principat de Catalunya
In a sandy-bed near Arenys de Mar (Barcelona, Spain) some algal species were collected, using scuba-diving techniques, at 25-32 m depth. Three of them were for the first time found in the catalan coast: Halymenia latifolia Crouan & Crouan, Halymenia floresia (Clemente) C. Agardh var. pinnata Codomier and Carpomitra costata (Stackhouse) Batters var. mediterranea Feldmann
Generation of Hâ‚‚ on Board Lng Vessels for Consumption in the Propulsion System
[Abstract] At present, LNG vessels without reliquefaction plants consume the BOG (boil-off gas) in their engines and the excess is burned in the gas combustion unit without recovering any of its energy content. Excess BOG energy could be captured to produce Hâ‚‚, a fuel with high energy density and zero emissions, through the installation of a reforming plant. Such
Hâ‚‚ production would, in turn, require on-board storage for its subsequent consumption in the propulsion plant when navigating in areas with stringent anti-pollution regulations, thus reducing COâ‚‚ and SOâ‚“ emissions. This paper presents a review of the different Hâ‚‚ storage systems and the methods of burning it in propulsion engines, to demonstrate the energetic viability thereof on board LNG vessels. Following the analysis, it is identified that a pressurised and cooled
H₂ storage system is the best suited to an LNG vessel due to its simplicity and the fact that it does not pose a safety hazard. There are a number of methods for consuming the H₂ generated in the DF engines that comprise the propulsión plant, but the use of a mixture of 70% CH₄-30% H₂ is the most suitable as it does not require any modifications to the
injection system. Installation of an on-board reforming plant and H₂ storage system generates sufficient H₂ to allow for almost 3 days’ autonomy with a mixture of 70%CH₄-30%H₂. This reduces the engine consumption of CH₄ by 11.38%,thus demonstrating that the system is not only energy-efficient, but lends greater versatility to the vessel
Synthesis of IAN-type N,N-Ligands via Dynamic Kinetic Asymmetric Buchwald-Hartwig Amination
The Pd-catalyzed coupling of racemic heterobiaryl bromides, triflates, or nonaflates with aryl/alkyl primary amines using QUINAP as the ligand provides the corresponding axially chiral heterobiaryl amines with excellent yields and enantioselectivities. Reactivity and structural studies of neutral and cationic oxidative addition intermediates support a dynamic kinetic asymmetric amination mechanism based on the labilization of the stereogenic axis in the latter and suggest that coordination of the amine to the Pd center is the stereodetermining step.Ministerio de Ciencia e Innovación CTQ2013-48164-C2-1-P, CTQ2013-48164-C2-2-P, RYC-2013-12585 for A.R.European FEDER FundsJunta de AndalucÃa 2012/FQM 1078
Classical models may be a better explanation of the Jiuzhang 1.0 Gaussian Boson Sampler than its targeted squeezed light model
Recently, Zhong et al. performed landmark Gaussian boson sampling experiments
with up to 144 modes using threshold detectors. The authors claim to have
achieved quantum computational advantage with the implementation of these
experiments, named Jiuzhang 1.0 and Jiuzhang 2.0. Their experimental results
are validated against several classical hypotheses and adversaries using tests
such as the comparison of statistical correlations between modes, Bayesian
hypothesis testing and the Heavy Output Generation (HOG) test. We propose an
alternative classical hypothesis for the validation of these experiments using
the probability distribution of mixtures of coherent states sent into a lossy
interferometer; these input mixed states, which we term squashed states, have
vacuum fluctuations in one quadrature and excess fluctuations in the other. We
find that for configurations in the high photon number density regime, the
comparison of statistical correlations does not tell apart the ground truth of
the experiment (two-mode squeezed states sent into an interferometer) from our
alternative hypothesis. The Bayesian test indicates that, for all
configurations excepting Jiuzhang 1.0, the ground truth is a more likely
explanation of the experimental data than our alternative hypothesis. A similar
result is obtained for the HOG test: for all configurations of Jiuzhang 2.0,
the test indicates that the experimental samples have higher ground truth
probability than the samples obtained form our alternative distribution; for
Jiuzhang 1.0 the test is inconclusive. Our results provide a new hypothesis
that should be considered in the validation of future GBS experiments, and shed
light into the need to identify proper metrics to verify quantum advantage in
the context of GBS. They also indicate that a classical explanation of the
Jiuzhang 1.0 experiment, lacking any quantum features, has not been ruled out.Comment: The code used to calculate threshold probabilities can be found in
the repository https://github.com/ polyquantique/torontonian-julia . All the
data used in the computation of the validation tests is available upon
reasonable request, or at https://doi.org/10.5281/zenodo.714102
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