Wave reflection at a free interface in an anisotropic pyroelectric medium with nonclassical thermoelasticity

In this paper, the well-established two-dimensional mathematical model for linear pyroelectric materials is employed to investigate the reflection of waves at the boundary between a vacuum and an elastic, transversely isotropic, pyroelectric material. A comparative study between the solutions of (a) classical thermoelasticity, (b) Cattaneo–Lord–Shulman theory and (c) Green–Lindsay theory equations, characterised by none, one and two relaxation times, respectively, is presented. Suitable boundary conditions are considered in order to determine the reflection coefficients when incident elasto–electro–thermal waves impinge the free interface. It is established that, in the quasi-electrostatic approximation, three different classes of waves: (1) two principally elastic waves, namely a quasi-longitudinal Primary (qP) wave and a quasi-transverse Secondary (qS) wave; and (2) a mainly thermal (qT) wave. The observed electrical effects are, on the other hand, a direct consequence of mechanical and thermal phenomena due to pyroelectric coupling. The computed reflection coefficients of plane qP waves are found to depend upon the angle of incidence, the elastic, electric and thermal parameters of the medium, as well as the thermal relaxation times. The special cases of normal and grazing incidence are also derived and discussed. Finally, the reflection coefficients are computed for cadmium selenide observing the influence of (1) the anisotropy of the material, (2) the electrical potential and (3) temperature variations and (4) the thermal relaxation times on the reflection coefficients

Electronic structure and magnetic properties of epitaxial FeRh(001) ultra-thin films on W(100)

Epitaxial FeRh(100) films (CsCl structure, $\sim 10\ ML\$ thick), prepared {\it in-situ} on a W(100) single crystal substrate, have been investigated via valence band and core level photoemission. The presence of the temperature-induced, first-order, antiferromagnetic to ferromagnetic (AF$\rightarrow$ FM) transition in these films has been verified via linear dichroism in photoemission from the Fe 3$p$ levels. Core level spectra indicate a large moment on the Fe atom, practically unchanged in the FM and AF phases. Judging from the valence band spectra, the metamagnetic transition takes place without substantial modification of the electronic structure. In the FM phase, the spin-resolved spectra compare satisfactorily to the calculated spin-polarized bulk band structure.Comment: 7 pages, 5 figure

Frequency Shifts in Natural Vibrations in Pantographic Metamaterials under Biaxial Tests

In this paper a 2D continuum model, thought as the homogenized limit of a microstructured pantographic sheet, is studied. The microstructure is characterized by two families of parallel fibers, whose deformation measures account for bending, elongation and relative rotation of the fibers. The deformation energy density of the homogenized model depends on both first and second gradients of the displacement. Modal analysis is performed in order to assess the peculiarities of the dynamic behavior of higher gradient models, and in particular the difference, with respect to classical laminae, in the dependence of the eigenfrequencies on the stiffness

Adult patients with grown-up congenital heart disease: Lights and shadows

GUCH is acronym of grown-up congenital heart of patients who become adults after cardiac surgery. The history of this population is in progress (temporal perspective), and long-term post-surgical follow-up revealed the paradoxical meaning of correction of complex congenital heart disease, because surgery does not restore normality: It prolongs life, improves symptoms, functional capacity, but it is often associated with illness and peculiar needs. Not only survival but also health-related quality of life, which is strictly connected to clinical status, socio-economic situation, psychological conditions, cognitive functions, level of care with particular attention to gender differences. Currently the history of these patients is better known: A multidisciplinary team of cardiologists with specific training in congenital heart disease, psychologists, neurophysiologists, obstetricians, social workers, experts in human science can improve the possibilities of these patients to realize their effective and safe project of life

Weakly Coupled Motion of Individual Layers in Ferromagnetic Resonance

We demonstrate a layer- and time-resolved measurement of ferromagnetic resonance (FMR) in a Ni81Fe19 / Cu / Co93Zr7 trilayer structure. Time-resolved x-ray magnetic circular dichroism has been developed in transmission, with resonant field excitation at a FMR frequency of 2.3 GHz. Small-angle (to 0.2 degree), time-domain magnetization precession could be observed directly, and resolved to individual layers through elemental contrast at Ni, Fe, and Co edges. The phase sensitivity allowed direct measurement of relative phase lags in the precession oscillations of individual elements and layers. A weak ferromagnetic coupling, difficult to ascertain in conventional FMR measurements, is revealed in the phase and amplitude response of individual layers across resonance.Comment: 22 pages, 6 figures submitted to Physical Review

Tracce, finestre, visioni

The issue of Engramma “Tracce Finestre Visioni” (Traces Windows Visions) collects a series of contributions focused on the relationship between text and image, with particular insistence on the boundary between them as labile, porous and fragile: with holes and gaps that take the form of windows; latencies and wounds that appear like visions; persistences that are perceivable as traces. The first section includes a group of essays on contemporary arts: Marina Apollonio, Fusionecircolare/ Endings. Tra arte cinetica e testo usicale elettroacustico, by Guglielmo Bottin; Embodiment vs Rejectingness. Per una evoluzione del “sistema di filtri” nell’opera di Pierre Bonnard (1925-1935), by Mario De Angelis; Esposizioni di niente/Testi per niente, by Massimo Maiorino; L’indicibile rappresentabile. Su Wittgenstein e Klee, by Enrico Palma; Indovinelli compositivi. Esercizi di John Hejduk per gli architetti del nuovo millennio, by Susanna Pisciella; Finestre letterarie e finestre visive. Sguardi esteriori e interiori fra tecnica e metafora, by Silvia Urbini; Pages d’un Journal de Chantier. Riflessi di Jean Cocteau in Berthold Lubetkin, by Chiara Velicogna; Steve McQueen. How Does One Believe in the Future? by Angela Vettese. The second section “Note e Recensioni” (Notes and Reviews) readings and reviews of exhibitions in display in Venice, more or less directly related to the Biennale 2022, are presented: Venezia “maternamente oscura”. Anish Kapoor alle Gallerie dell’Accademia e a Palazzo Manfrin (aprile/ottobre 2022), by Michela Maguolo; An Archaeology of Silence. Recensione della mostra di Kehinde Wiley (Venezia 2022), by Asia Benedetti; L’incantesimo del fuoco. Sulla mostra “On Fire” alla Fondazione Cini (Venezia 2022), by Andrea Cortellessa; “Cromocracy”. Sulla mostra di Abel Herrero alla Galleria Castello (Venezia 2022), by Andrea Cortellessa. The section also includes a Note on the comparison between 1968 and 2022 wartime covers of the periodical “Time”: What a Time! Il ritorno del passato tra shock e continuità in due copertine del “Time”, by Francesco Giosuè. Closing the section, as well as the issue itself, are the presentations of three recent volumes that intersect the theme of the text/image/vision relationship: La memoria di un gesto. Presentazione di La memoria in tasca di Emanuele Pellegrini, by Silvia De Min; Sogno e visione, secondo David Lynch. Presentazione di: Nicola Settis, Chi è il sognatore? Guida alla visione di Twin Peaks 3, edited by Ilaria Grippa and Monica Centanni; abbecedari di Architettura di Sergio Polano. Presentazione di Beppe Cantele

phase coexistence in two dimensional fe 0 70 ni 0 30 films on w 110

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