Application of solar arrays in high-energy gamma-ray astronomy

Summary The previously suggested use of large solar-energy arrays for additional applications in astronomy and astrophysics is herein analysed for the case of high-energy gamma-ray astronomy. We have studied by Monte Carlo techniques the response of an array of 800 m² reflective area to the Čerenkov light produced by relativistic electrons of high-energy cascades, initiated by primary cosmic rays (gamma-rays and protons) in the Earth's atmosphere. The calculation shows that night-time use of these devices may give information on the study of gamma-ray sources which is consistent with the results obtained from specific apparatuses, from the point of view of both energy threshold and detectable fluxes. This result confirms the possibility of designing multiscope arrays operating daily as solar-energy collectors and at night-time as cosmic gamma-ray detectors, with obvious advantages from the financial point of view.

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Riassunto Si analizza la possibile utilizzazione dei campi eliostatici per applicazioni di tipo astrofisico nel caso dell'astronomia gamma di alta energia. Le prestazioni di un apparato con superficie riflettente di 800 m² come raccoglitore della luce Čerenkov emessa dagli elettroni relativistici di sciami estesi atmosferici (EAS) sono state studiate con un metodo di Montecarlo. I calcoli mostrano che l'uso notturno di questo sistema per la ricerca di sorgenti gamma può fornire risultati confrontabili con quelli ottenuti da apparati specifici, sia per quanto riguarda la soglia di rivelazione (E _s<100 GeV) che i flussi rivelabili. Dati gli ovvi vantaggi di tipo economico, questo risultato suggerisce la possibilità di progettare gli apparati in modo multiuso, cioè tali da poter operare come collettori solari nelle ore diurne e come rivelatori di EAS in quelle notturne.

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Резюме В этой работе анализируется применение больших солнечных антенных решеток для случая гамма-астрономии высоких энергий. Мы исследуем с помощью метода Монте-Карло отклик антенной решетки 800 м² на черенковское излучение, образованное релятивистскими электронами в широких атмосферных ливнях. Вычисления показывают, что использование таких приборов в ночное время может дать информацию об источниках гамма-лучей, которая согласуется с результатами, полученными с помощью специальной аппаратуры, с точки зрения энергетического порогаE _s<100 ГэВ и с точки зрения детектируемых потоков. Этот результат подтверждает возможность многоцелевого использования антенных решеток; в дневное время как коллекторов солнечной энергии, а в ночное время как детекторов космических гамма-лучей.

     

Theoretical study of the potential energy curves of the diatomic radicals MeIIX. III. Application to MgCl,CaF and CaCl radicals and some preliminary remarks

The series of calculations of the potential energy curves of the diatomic radicals Me_IIX (Me_II = second group metal, X = halogen), has been extended to MgCl, CaF and CaCl. The calculations have been performed according to a stepwise procedure, outlined in previous works. The presently available results allow comparisons for the first members of the series.     

Glass transition temperatures of some linear polymers containing phenyl side groups

The glass transition temperatures of a number of poly(vinyl phenyl ketones), poly-(vinyl benzoates), and poly(phenyl acrylates) have been measured by a refractometric method. The effects exerted on T_g by the nature and position of the ring substituents and by the different groups binding the pendant phenyl rings to the polyvinyl chain are discussed. The importance of knowledge of the side-group motions in the glassy state for the interpretation of glass temperature data is emphasized.     

A Diffusive Strategic Dynamics for Social Systems

We propose a model for the dynamics of a social system, which includes diffusive effects and a biased rule for spin-flips, reproducing the effect of strategic choices. This model is able to mimic some phenomena taking place during marketing or political campaigns. Using a cost function based on the Ising model defined on the typical quenched interaction environments for social systems (Erdös-Renyi graph, small-world and scale-free networks), we find, by numerical simulations, that a stable stationary state is reached, and we compare the final state to the one obtained with standard dynamics, by means of total magnetization and magnetic susceptibility. Our results show that the diffusive strategic dynamics features a critical interaction parameter strictly lower than the standard one. We discuss the relevance of our findings in social systems.     

The motion of a solid with large deformations

We study the motion of a solid with large deformations. The solid may be loaded on its surface by needles, rods, beams, plates… Therefore it is wise to choose a third-gradient theory for the body. Stretch matrix of the polar decomposition has to be symmetric. This is an internal constraint which introduces a reaction stress in the Piola–Kirchhoff–Boussinesq stress. We prove that there exists a motion that satisfies the complete equations of Mechanics in a convenient variational framework. This motion is local-in-time because it may be interrupted by crushing, resulting in a discontinuity of velocity with respect to time, i.e., an internal collision.     

Labeled sequent calculi for modal logics and implicit contractions

The paper settles an open question concerning Negri-style labeled sequent calculi for modal logics and also, indirectly, other proof systems which make (more or less) explicit use of semantic parameters in the syntax and are thus subsumed by labeled calculi, like Brünnler’s deep sequent calculi, Poggiolesi’s tree-hypersequent calculi and Fitting’s prefixed tableau systems. Specifically, the main result we prove (through a semantic argument) is that labeled calculi for the modal logics K and D remain complete w.r.t. valid sequents whose relational part encodes a tree-like structure, when the unique rule which contains an harmful implicit contraction—by which the condition that the premises be less complex than the conclusion is violated—is modified into a contraction-free one respecting the latter condition, thus making the proof-search space finite.     

Kinetic study on effect of novel cationic dimeric surfactants for the cleavage of carboxylate ester

Kinetic study has been performed to understand the reactivity of novel cationic gemini surfactants viz. alkanediyl‐α,ω‐bis(hydroxyethylmethylhexadecylammonium bromide) C₁₆‐s‐C₁₆ MEA, 2Br^? (where s = 4, 6) in the cleavage of p‐nitrophenyl benzoate (PNPB). Novel cationic gemini C₁₆‐s‐C₁₆ MEA, 2Br^? surfactants are efficient in promoting PNPB cleavage in presence of butane 2,3‐dione monoximate and N‐phenylbenzohydroxamate ions. Model calculation revealed that the higher catalytic effect of ethanol moiety of gemini surfactants (C₁₆H₃₃N⁺ C₂H₄OH CH₃ (CH₂)_S N⁺ C₂H₄OH CH₃C₁₆H₃₃, 2Br^?, s = 4, 6) is due to their higher binding capacity toward substrate. This is in line with finding that binding constants for novel series of cationic gemini surfactants are higher than conventional cationic gemini (C₁₆H₃₃N⁺(CH₃)₂(CH₂)_SN⁺(CH₃)₂C₁₆H₃₃, 2Br^?, s = 10, 12), cetyldimethylethanolammonium bromide and zwitterionic surfactants, i.e. C_nH_2n+1N⁺Me₂ (CH₂)₃ SO₃^? (n = 10; SB3‐10). The fitting of kinetic data was analyzed by the pseudophase model. Copyright © 2013 John Wiley & Sons, Ltd.     

Analysis of spectral Hamiltonian boundary value methods (SHBVMs) for the numerical solution of ODE problems

Numerical Algorithms - Recently, the numerical solution of stiffly/highly oscillatory Hamiltonian problems has been attacked by using Hamiltonian boundary value methods (HBVMs) as spectral methods...