90,671 research outputs found

    Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes

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    Oxygen reduction and transport properties of the electrolyte in the phosphoric acid fuel cell are studied. The areas covered were: (1) development of a theoretical expression for the rotating ring disk electrode technique; (2) determination of the intermediate reaction rate constants for oxygen reduction on platinum in phosphoric acid electrolyte; (3) determination of oxygen reduction mechanism in trifluoreomethanesulfonic acid (TFMSA) which was considered as an alternate electrolyte for the acid fuel cells; and (4) the measurement of transport properties of the phosphoric acid electrolyte at high concentrations and temperatures

    Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes

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    Oxygen reduction and transport properties of the electrolyte in the phosphoric acid fuel cell are studied. A theoretical expression for the rotating ring-disk electrode technique; the intermediate reaction rate constants for oxygen reduction on platinum in phosphoric acid electrolyte; oxygen reduction mechanism in trifluoromethanesulfonic acid (TFMSA), considered as an alternate electrolyte for the acid fuel cells; and transport properties of the phosphoric acid electrolyte at high concentrations and temperatures are covered

    Exotic-Hadron Signature by Constituent-Counting Rule in Perturbative QCD

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    We explain a method to find internal quark configurations of exotic hadron candidates by using the constituent counting rule. The counting rule was theoretically predicted in perturbative QCD for hard exclusive hadron reactions, and it has been tested in experiments for stable hadrons including compound systems of hadrons such as the deuteron, 3^3H, and 3^3He. It indicates that the cross section scales as dσ/dt∼1/sn−2d\sigma /dt \sim 1/s^{n-2}, where ss is the center-of-mass energy squared and nn is the total number of constituents. We apply this method for finding internal configurations of exotic hadron candidates, especially Λ(1405)\Lambda (1405). There is a possibility that Λ(1405)\Lambda (1405) could be five-quark state or a KˉN\bar K N molecule, and scaling properties should be different between the ordinary three-quark state or five-quark one. We predict such a difference in π−+p→K0+Λ(1405)\pi^- + p \to K^0 + \Lambda (1405), and it could be experimentally tested, for example, at J-PARC. On the other hand, there are already measurements for γ+p→K++Λ(1405)\gamma + p \to K^+ + \Lambda (1405) as well as the ground Λ\Lambda in photoproduction reactions. Analyzing such data, we found an interesting indication that Λ(1405)\Lambda (1405) looks like a five-quark state at medium energies and a three-quark one at high energies. However, accurate higher-energy measurements are necessary for drawing a solid conclusion, and it should be done at JLab by using the updated 12 GeV electron beam. Furthermore, we discuss studies of exotic hadron candidates, such as f0(980)f_0 (980) and a0(980)a_0 (980), in electron-positron annihilation by using generalized distribution amplitudes and the counting rule. These studies should be possible as a KEKB experiment.Comment: 6 pages, LaTeX, 10 eps files, to be published in JPS Conf. Proc., Proceedings of the 14th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU2016), July 25-30, 2016, Kyoto, Japa

    The NLO QCD Corrections to BcB_c Meson Production in Z0Z^0 Decays

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    The decay width of Z0Z^0 to BcB_c meson is evaluated at the next-to-leading order(NLO) accuracy in strong interaction. Numerical calculation shows that the NLO correction to this process is remarkable. The quantum chromodynamics(QCD)renormalization scale dependence of the results is obviously depressed, and hence the uncertainties lying in the leading order calculation are reduced.Comment: 14 pages, 7 figures; references added; expressions and typos ammende

    Collisions of antiprotons with hydrogen molecular ions

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    Time-dependent close-coupling calculations of the ionization and excitation cross section for antiproton collisions with molecular hydrogen ions are performed in an impact-energy range from 0.5 keV to 10 MeV. The Born-Oppenheimer and Franck-Condon approximations as well as the impact parameter method are applied in order to describe the target molecule and the collision process. It is shown that three perpendicular orientations of the molecular axis with respect to the trajectory are sufficient to accurately reproduce the ionization cross section calculated by [Sakimoto, Phys. Rev. A 71, 062704 (2005)] reducing the numerical effort drastically. The independent-event model is employed to approximate the cross section for double ionization and H+ production in antiproton collisions with H2.Comment: 12 pages, 5 figures, 4 table

    Microwave emission from snow and glacier ice

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    The microwave brightness temperature for snow fields was studied assuming that the snow cover consists of closely packed scattering spheres which do not interact coherently. The Mie scattering theory was used to compute the volume scattering albedo. It is shown that in the wavelength range from 0.8 to 2.8 cm, most of the micro-radiation emanates from a layer 10 meters or less in thickness. It is concluded that it is possible to determine snow accumulation rates as well as near-surface temperature

    A statistical technique for determining rainfall over land employing Nimbus-6 ESMR measurements

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    An empirical method was employed to delineate synoptic scale rainfall over land utilizing Nimbus-6 ESMR measurements
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