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Synchronization of two coupled pendula in absence of escapement

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Applied Mathematics and Mechanics(English Edition) 2016年第12期37卷 1721-1738页

作者： F.TALAMUCCI diMAI Dipartimento di Matematica e Informatica "Ulisse Dini"Università degli Studi di Firenze

A model of two oscillating pendula placed on a mobile support is studied. Once an overall scheme of equations, under general assumptions, is formulated via the Lagrangian equations of motion, the specific case of absence of escapement is examined. The mechanical model consists of two coupled pendula both oscillating on a moving board attached to a spring. The final result performs selection among the peculiar parameters of the physical process （the length, the ratio of masses, the friction and damping coefficients, and the stiffness of the spring）, providing a tendency to synchronization.

关键词： synchronization coupled pendula characteristic equation eigenvalue lo-calization

Flash flood sediment transport in a steep sand-bed ephemeral stream

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International Journal of Sediment Research 2011年第2期26卷 193-209页

作者： Paolo BILLI dipartimento di Scienze della Terra Universita di Ferrara

This paper reports about flow and sediment transport measurements undertaken during the rainy season(July-August) 2008 on Gereb Oda,a steep,sand-bed ephemeral stream,draining the western margin of the Kobo structural basin in northern *** Oda streambed is dry for most of the year since it is subjected only to sporadic flash floods in response to individual,high intensity and spatially confined *** about hydraulic and sediment transport processes in steep sand-bed,ephemeral stream is very poor and,though only two flash floods occurred during the field campaign,the data gathered may contribute to improve our knowledge on these kind of *** numbers were calculated in order to verify the occurrence of supercritical flow conditions as postulated by a few authors from the analysis of sedimentary structures *** data are also compared to simple models to predict flow velocity and discharge since flow recording systems are seldom installed on ephemeral streams in remote areas and developing *** rivers are known for their very high suspended sediment transport,but very little bedload data exist for sand-bed,ephemeral *** variation of suspended sediment concentration with discharge is analysed and simple rating curves for both suspended and bed load transport are derived.A few equations to predict bedload are tested against Gereb Oda data and the relationship between en masse bedload transport processes as thin sand sheets and the development of horizontal lamination through the migration of leaf-shaped,sheet-like bedforms is ***,large boulders were observed to move at flow depths of the same order of magnitude of their size.A few functions to predict the threshold conditions for large particles entrainment are used to verify if and to what extent they match Gereb Oda field *** increased density of the water-sediment mixture,for the very high suspended sediment concentr

关键词： Ephemeral stream Bedload Suspended load Flash flood Ethiopia

First-principles search of hot superconductivity in La-X-H ternary hydrides

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npj Computational Materials 2022年第1期8卷 1-8页

作者： Simone di Cataldo Wolfgang von der Linden Lilia Boeri Institute of Theoretical and Computational Physics Graz University of TechnologyNAWI Graz8010GrazAustria dipartimento di fisica Sapienza Universitàdi Roma00185RomaItaly Centro Ricerche Enrico Fermi Via Panisperna89a00184RomaItaly

Motivated by the recent claim of hot superconductivity with critical temperatures up to 550 K in La + x hydrides,we investigate the high-pressure phase diagram of compounds that may have formed in the experiment,using first-principles calculations for evolutionary crystal structure prediction and *** from the hypothesis that the observed T_(c) may be realized by successive heating upon a pre-formed LaH_(10) phase,we examine plausible ternaries of lanthanum,hydrogen and other elements present in the diamond anvil cell: boron,nitrogen,carbon,platinum,gallium,*** find that only boron and,to a lesser extent,gallium form metastable superhydride-like structures that can host high-T_(c) superconductivity,but the predicted T_(c)’s are incompatible with the experimental *** results indicate that,while the claims of hot superconductivity should be reconsidered,it is very likely that unknown H-rich ternary or multinary phases containing lanthanum,hydrogen,and possibly boron or gallium may have formed under the reported experimental conditions,and that these may exhibit superconducting properties comparable,or even superior,to those of currently known hydrides.

关键词： hydrides boron superconductivity

The role of structural inheritance in continental break-up and exhumation of Alpine Tethyan mantle(Canavese Zone,Western Alps)

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Geoscience Frontiers 2020年第1期11卷 167-188页

作者： Andrea Festa Gianni Balestro Alessandro Borghi Sara De Caroli Andrea Succo dipartimento di Scienze della Terra Universitàdi TorinoTorinoItaly dipartimento di Scienze Chimiche della Vita e della SostenibilitàAmbientaleUniversitàdi ParmaParmaItaly

The Canavese Zone(CZ)in the Western Alps represents the remnant of the distal passive margin of the Adria microplate,which was stretched and thinned during the Jurassic opening of the Alpine *** detailed geological mapping,stratigraphic and structural analyses,we document that the continental break-up of Pangea and tectonic dismemberment of the Adria distal margin,up to mantle rocks exhumation and oceanization,did not simply result from the syn-rift Jurassic extension but was strongly favored by older structu ral inheritances(the Proto-Canavese Shear Zone),which controlled earlier lithospheric *** findings allowed to redefine in detail(i)the tectono-stratigraphic setting of the Variscan metamorphic basement and the Late Carbonife rous to Early Cretaceous CZ succession,(ii)the role played by inherited Late Carboniferous to Early Triassic structures and(iii)the significance of the CZ in the geodynamic evolution of the Alpine *** large amount of extensional displacement and crustal thinning occurred during different pulses of Late Carbonife rous-Early Triassic strike-slip tectonics is wellconsistent with the role played by long-lived regional-scale wrench faults(e.g.,the East-Variscan Shear Zone),suggesting a re-discussion of models of mantle exhumation driven by low-angle detachment faults as unique efficient mechanism in stretching and thinning continental crust.

关键词： Alpine Tethys Western Alps Jurassic ophiolite Structural inheritance Continental break-up Mantle exhumation

Silver impregnated carbon for adsorption and desorption of elemental mercury vapors

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Journal of Environmental Sciences 2011年第9期23卷 1578-1583页

作者： Despina Karatza Marina Prisciandaro Amedeo Lancia dino Musmarra dipartimento di Ingegneria Chimica Universitàdi Napoli "Federico II" dipartimento di Chimica Ingegneria Chimica e MaterialiUniversitàde L’Aquila Centro Interdipartimentale di Ricerca in Ingegneria Ambientale Dipartimento di Ingegneria CivileSeconda Universitàdegli Studi di NapoliReal Casa dell’AnnunziataVia Roma 2981031 Aversa (CE)Italy

The Hg 0 vapor adsorption experimental results on a novel sorbent obtained by impregnating a commercially available activated carbon （Darco G60 from BDH） with silver nitrate were *** study was performed by using a fundamental approach,in an apparatus at laboratory scale in which a synthetic flue gas,formed by Hg 0 vapors in a nitrogen gas stream,at a given temperature and mercury concentration,was flowed through a fixed bed of adsorbent *** curves and adsorption isotherms were obtained for bed temperatures of 90,120 and 150°C and for Hg 0 concentrations in the gas varying in the range of 0.8–5.0 mg/m 3 .The experimental gas-solid equilibrium data were used to evaluate the Langmuir parameters and the heat of *** experimental results showed that silver impregnated carbon was very effective to capture elemental mercury and the amount of mercury adsorbed by the carbon decreased as the bed temperature *** addition,to evaluate the possibility of adsorbent recovery,desorption was also *** runs showed that both the adsorbing material and the mercury could be easily recovered,since at the end of desorption the residue on solid was almost *** material balance on mercury and the constitutive equations of the adsorption phenomenon were integrated,leading to the evaluation of only one kinetic parameter which fits well both the experimentally determined breakthrough and desorption curves.

关键词： mercury carbon MSW incinerators adsorption desorption silver nitrate

The Relativistic Three-dimensional Evolution of SN 1987A

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International Journal of Astronomy and Astrophysics 2014年第2期4卷 359-364页

作者： Lorenzo Zaninetti dipartimento di fisica Turin Italy

The high velocities observed in supernovae require a relativistic treatment for the equation of motion in the presence of gradients in the density of the interstellar medium. The adopted theory is that of the thin layer approximation. The chosen medium is auto-gravitating with respect to an equatorial plane. The differential equation which governs the relativistic conservation of momentum is solved numerically and by recursion. The asymmetric field of relativistic velocities as well the time dilation is plotted at the age of 1 yr for SN 1987A.

关键词： Supernovae General Supernovae Individual (SN 1987A) ISM Supernova Remnants

Singular Integrals with Bilinear Phases

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Acta Mathematica Sinica,English Series 2006年第1期22卷 251-260页

作者： Elena PRESTINI dipartimento di Matematica Universita di Roma 'Tor Vergata' Roma 00133 Italy

We prove the boundedness from Lp（T2） to itself, 1 〈 p 〈∞, of highly oscillatory singular integrals Sf（x, y） presenting singularities of the kind of the double Hilbert transform on a non-rectangular domain of integration, roughly speaking, defined by ｜y′｜〉｜x′｜, and presenting phases λ（Ax ＋ By） with 0≤ A, B ≤ 1 and λ≥ 0. The norms of these oscillatory singular integrals are proved to be independent of all parameters A1 B and A involved. Our method extends to a more general family of phases. These results are relevant to problems of almost everywhere convergence of double Fourier and Walsh series.

关键词： Hardy-Littlewood maximal function Maximal Hilbert transform Maximal Carleson operator Oscillatory singular integrals a.e. convergence of double Fourier series

Analysis on parallel implementations of fixed-complexity sphere decoder

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Science China(Information Sciences) 2013年第4期56卷 155-165页

作者： WU Bin MASERA Guido VLSI Lab Dipartimento di ElettronicaPolitecnico di TorinoTorino 10129Italy

Sphere decoders are widely investigated for the implementation of multiple-input multiple-output(MIMO) *** a large number of sphere decoding algorithms,the fixed-complexity sphere decoder(FSD) exhibits remarkable advantages in terms of constant throughput and high flexibility of parallel *** this paper,we present a four-nodes-per-cycle parallel FSD architecture with balanced performance and hardware complexity,and several examples of VLSI implementation for different types of modulation and both real and complex signal *** aspects and architecture details are analyzed in order to present a hardware-level perspective of the FSD *** a variety of performance-complexity trade-offs are *** implementation results show that the proposed parallel FSD architecture is highly efficient and flexible,especially in the complex signal model.

关键词： MIMO detection fixed-complexity sphere decoder parallel architecture VLSI implementation

Spectral properties of Tm,Ho:LiYF_4 laser crystal

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Journal of Rare Earths 2011年第6期29卷 592-595页

作者：李春张莹张学建曾繁明 Mauro Tonelli 刘景和 School of Materials Science and Engineering Changchun University of Science and Technology Office of Foreign Affairs Jilin Architectural and Civil Engineering Institute NEST-CNR and dipartimento di fisica Universita` di Pisa Largo B. Pontecorvo 3 56127 Pisa Italy

The LiYF4 single crystal codoped with thulium and holmium ions was successfully grown by the Cz method. The optimal technical parameters obtained were as follows： the pulling rate was 0.16 mm/h; the rotation speed was 3 rpm; the cooling rate was 15 °C/h. The result of XRD curve showed that as-grown Tm,Ho：LiYF4 laser crystal belonged to the monoclinic system with scheelite-type structure and space group I41/a. The cell parameters calculated were： a=0.52160 nm, c=1.09841 nm and Z=4. Absorption and fluorescence spectra of Tm,Ho：LiYF4 laser crystal at room temperature were measured and analysed. The absorption cross section, FWHM and absorption coefficient at 779.3 nm calculated were 7.44×10–21 cm2, 8.7 nm and 2.23 cm–1, respectively. An intensive fluorescence emission peak appeared near 2045 nm. The emission cross section and fluorescence lifetime were 0.87×10–20 cm2 and 10.8 ms, respectively. The ratio of Tm–Ho transfer to its back-transfer process was 10.6.

关键词： Tm Ho:LiYF4 laser crystal Cz method absorption spectrum fluorescence spectrum rare earths