577,766 research outputs found

    Comment on Universal Reduced Potential Function for Diatomic Systems

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    First principles prove why a recent claim by R.H. Xie and P.S. Hsu (Phys. Rev. Lett. 96, 243201 (2006)) on the scaling power of a covalent Sutherland parameter to expose a universal function cannot be validated.Comment: 1 page, at the UGent archive, 11 references, revised for publication in PR

    Comment on Proof that the Hydrogen-Antihydrogen Molecule is Unstable

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    A recent claim that molecule H-antiH is unstable cannot be a proof as it is based on a wrong conjecture. This is illustrated with 4 examples, including observed natural hydrogen-antihydrogen oscillations never detected previously.Comment: 1 page, 1 figure, formatted for submission as a comment to PRL, typo's removed, more text adaptation

    Nitrogen efficiency of dairy cattle : from protein evaluation to ammonia emission

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    Diet optimization contributes considerably to increased nitrogen efficiency of dairy cattle, resulting in reduced nitrogen losses. This thesis focuses on three themes: the potential advances in protein evaluation systems for ruminants, the relationship between dairy cow diet and ammonia emission and the opportunities to monitor ammonia emission from dairy cow barns by application of milk urea content as a practical indicator. Overall, the present work shows that farm management can be aimed at increased nitrogen efficiency of dairy cattle and reduced ammonia emission without compromising other sustainability objectives such as the integral ecological footprint, animal health and farm profitability. </p

    Ionic Kratzer bond theory and vibrational levels for achiral covalent bond HH

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    A dihydrogen Hamiltonian reduces to the Sommerfeld-Kratzer-potential, adapted for field quantization according to old-quantum theory. Constants omega_e, k_e and r_e needed for the H_2 vibrational system derive solely from hydrogen mass m_H. For H_2, a first principles ionic Kratzer oscillator returns the covalent bond energy within 0,08 % and all levels within 0,02 %, 30 times better than the Dunham oscillator and as accurate as early ab initio QM.Comment: 21 pages, 4 figures, 2 tables, at the institutional archive Ghent University, references and early ab initio QM results added, typo's remove

    Optimal greenhouse cultivation control: survey and perspectives

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    Abstract: A survey is presented of the literature on greenhouse climate control, positioning the various solutions and paradigms in the framework of optimal control. A separation of timescales allows the separation of the economic optimal control problem of greenhouse cultivation into an off-line problem at the tactical level, and an on-line problem at the operational level. This paradigm is used to classify the literature into three categories: focus on operational control, focus on the tactical level, and truly integrated control. Integrated optimal control warrants the best economical result, and provides a systematic way to design control systems for the innovative greenhouses of the future. Research issues and perspectives are listed as well

    On mirror symmetry, CSB and anti-hydrogen states in natural atom H

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    Molecular band spectra reveal a left-right symmetry for atoms (Van Hooydonk, Spectrochim.Acta A, 2000, 56, 2273). Intra-atomic left-right symmetry points to antiatom states and, to make sense, this must also show in line spectra. H Lyman ns-states show a mirror plane at quantum number n=pi/2. Symmetry breaking oscillator (1-0.5pi/n)sup(2) means that some of these n-states are anti-hydrogenic. This view runs ahead of CERN AD-projects on antihydrogen.Comment: 2 pages, 1 fig., contribution at conference PSAS2002, Sint Petersbur

    Mexican hat curve for hydrogen- and antihydrogen-states in natural atom H

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    Molecular band spectra as well as atomic line spectra reveal a left-right symmetry for atoms (Van Hooydonk, Spectrochim. Acta A, 2000, 56, 2273 and Phys. Rev. A 66, 044103 (2002). We now extract a Mexican hat shaped or double well curve from the line spectrum (Lyman ns-series) of natural atom H. An H CSB theory and its oscillator contribution (1-0.5pi/n)sup(2)/nsup(2) lead to unprecedented results for antihydrogen physics, ahead of the CERN-AD-project on artificial antihydrogen.Comment: 4 pages, 1 fig., lecture at Wigner Centennial 2002, Pecs, Hungar

    Five-fold symmetry in fractal atom hydrogen probed with accurate 1S-nS terms

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    We probe Penrose's five-fold symmetry and fractal behavior for atom H. With radius r(H) derived from H mass m(H), H symmetry is governed by Euclid's golden ratio phi=0,5(sqrt(5)-1), as proved with accurate H terms. A Hund-type Mexican hat curve in the natural H spectrum points to mirrored antihydrogen Hbar. We predict that term H 1S-3S, to be measured soon, is 2 922 743 278 654 kHz.Comment: 9 pages, 2 figures, 2 tables, typo's remove
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