Finite element incremental analysis of elastoplastic plate bending

Summary The paper discusses the numerical solution of the elastoplastic bending of plates with any polygonal boundary subject to a generic load and to distributed dislocations.For the discretization of the plate Herrmann's and Hellan's constant moment triangular equilibrium model has been chosen. Compatibility is imposed through a minimum principle, proposed by Capurso and Maier, which can be considered a generalization of the minimum complementary energy principle for elastoplastic workhardening continua allowing for distributed dislocations.By means of a completely automatic computation program, the cases of simply supported and clamped square plate under uniformly distributed load and under central concentrated load are solved. Present results are partly compared with existing solutions.

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Sommario Viene studiato il problema della flessione di una piastra a contorno poligonale qualsiasi costituita da materiale elastico-incrudente e sottoposta ad un carico generico e a distorsioni diffuse. Per la discretizzazione della piastra viene scelto il modello triangolare equilibrato a momento costante di Herrmann e Hellan. La congruenza viene imposta attraverso un principio di minimo proposto da Capurso e Maier che può essere riguardato come la generalizzazione del principio della minima energia complementare per materiali elastico-incrudenti in presenza di distorsioni diffuse.Viene sviluppato un programma di calcolo automatico, che stende sulla piastra un reticolo di densità prefissata, numera e collega fra di loro nodi, lati e triangoli. In tal modo il programma genera le condizioni di equilibrio nodale e costruisce la funzione dell'energia da minimizzare. Vengono risolti, per il confronto con le soluzioni esistenti i casi di piastra quadrata semplicemente appoggiata e incastrata al contorno sottoposte a carico uniforme e ad una forza concentrata nel centro.

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This study forms part of a research program supported by the National (Italian) Research Council (C.N.R. Gruppo Problemi avanzati di ingegneria strutturale).     

Experimental demonstration of decoherence-free one-way information transfer

We report the experimental demonstration of a one-way quantum protocol reliably operating in the presence of decoherence. Information is protected by designing an appropriate decoherence-free sub-space for a cluster state resource. We demonstrate our scheme in an all-optical setup, encoding the information into the polarization states of four photons. A measurement-based one-way information-transfer protocol is performed with the photons exposed to severe symmetric phase-damping noise. Remarkable protection of information is accomplished, delivering nearly ideal outcomes.     

Sesquiterpene compounds from Inula viscosa

Two new compounds, 2,5-dihydroxyisocostic acid and 2,3-dihydroxycostic acid together with three known sesquiterpene compounds, Isocostic acid, Carabrone and Tomentosin, have been isolated from the acetone extract of Inula viscosa (L.) Aiton. The structures of all new compounds were determined by spectroscopic methods, in particular 1D and 2D (1)H- and (13)C-NMR. The (13)C-NMR spectra of Isocostic acid and of Tomentosin are reported here for the first time.     

De curvatura superficierum quaestiones

Annali di Matematica Pura ed Applicata (1858-1865) -     

Structural homologies in benzylamino-N,N-bis methylphosphonic acid and its layered zirconium derivative

A new layered zirconium diphosphonate fluoride, ZrF(O₃PCH₂)₂NHCH₂C₆H₅ has been prepared and its structure determined ab initio by X-ray powder data and refined with the Rietveld method (orthorhombic, , , , space group Pbca, , Z=8, R_wp=0.080). Both phosphonic groups of each diphosphonate building block are bonded to zirconium atoms on the same side of each layer. Benzyl groups from adjacent layers are interdigitated in the interlayer region, with probable π-π stacking interactions. The structure of the free benzylamino-N,N-bis methylphosphonic acid has been determined by single crystal X-ray data (monoclinic, space group P2₁, , , , β=92.930(3)°, , Z=2, R₁=0.072, wR₂=0.150). As in the zirconium derivative, benzyl groups from adjacent layers are interdigitated and create a regular alternation of polar and non-polar regions.     

Quantum Work Statistics with Initial Coherence

The two-point measurement scheme for computing the thermodynamic work performed on a system requires it to be initially in equilibrium. The Margenau–Hill scheme, among others, extends the previous approach to allow for a non-equilibrium initial state. We establish a quantitative comparison between both schemes in terms of the amount of coherence present in the initial state of the system, as quantified by the l1-coherence measure. We show that the difference between the two first moments of work, the variances of work, and the average entropy production obtained in both schemes can be cast in terms of such initial coherence. Moreover, we prove that the average entropy production can take negative values in the Margenau–Hill framework.     

The Structures,Morphologies, and Photophysical Properties of Multiluminescent Layered Lanthanide–Phosphono–Carboxylate Nanoparticles

A new family of layered metal(III)–phosphono–carboxylate nanostructures (M=Y, Eu, Tb, Er, and Yb) was hydrothermally synthesized and their structures and morphologies were characterized by X‐ray powder diffraction and TEM. 4‐[Bis(phosphonomethyl)amino]caproic acid and 4‐ [bis(phosphonomethyl)amino]undecan‐ oic acid, with general formula (H₂O₃PCH₂)₂NR (R=C₅H₁₀COOH (P2CAPR) and C₁₀H₂₂COOH (P2UND), respectively) were used as building blocks for the preparation of novel layered hybrid materials in which the inorganic layers were composed of MO₇ or MO₈ polyhedra and PO₃C tetrahedra. The interlayer region was occupied by carboxyalkyl chains. These layered compounds were easily dispersed as stable solutions in alkylamine/water upon ultrasonication. These dispersions were constituted of rectangular elongated nanoparticles (NPs), which showed a distribution of sizes ranging from 20–500 nm. These new materials had interesting photophysical properties because they were multiluminescent compounds. These properties gave rise to several emission bands, which were spread over the broad spectroscopic region, from the near‐UV up to the near‐IR regions. Each emission band had a specific lifetime, which ranged from the sub‐ps to the ms scale.     

Exact solution of the 1D Hubbard model in the atomic limit with inter-site magnetic coupling

In this paper, we present for the first time the exact solution in the narrow-band limit of the 1D extended Hubbard model with nearest-neighbour spin-spin interactions described by an exchange constant J. An external magnetic field h is also taken into account. This result has been obtained in the framework of the Green’s functions formalism, using the composite operator method. By means of this theoretical background, we have studied some relevant features such as double occupancy, magnetization, spin-spin and charge-charge correlation functions and derived a phase diagram for both ferro (J > 0) and anti-ferro (J < 0) coupling in the limit of zero temperature. We also report a study on density of states, specific heat, charge and spin susceptibilities. In the limit of zero temperature, we show that the model exhibits a very rich phase diagram characterized by different magnetic orders and by the coexistence of charge and spin orderings at commensurate filling. Moreover, our analysis at finite temperature of density of states and response functions shows the presence of low-temperature charge and spin excitations near the phase boundaries.