A new modeling of the X-ray diffraction by disordered lamellar structures, such as phyllosilicates.

The “classical” modeling of powder X-ray diffraction (XRD) patterns of lamellar structures, such as phyllosilicates, assumes that the samples are composed of “crystals” having various thickness and well-defined translations between layers. This model is able to describe the high-angle domain of XRD patterns but sometimes fails in the low-angle region. The new model proposed here considers the samples to be composed of “particles” that have larger sizes than crystals and contain defects such as cracks, inner-porosity, bent layers, edge dislocations, etc. These defects induce variations in the d-spacings, introduced in the calculation by distributions of the d-spacings. For phyllosilicates, this model is consistent not only with XRD, but also with small-angle X-ray scattering (SAXS) data, transmission electron microscopy (TEM) results, and high-resolution transmission electron microscopy (HRTEM) observations

Numerical simulation of the stabilisation of the steady state operation of an alternator feeding an infinite busbar by a circuit field coupled model.

In this paper, the authors present a study of the stabilisation of the steady state operation of an alternator by means of a time stepped 2D finite element field circuit coupled model. The results of the study show that it can be very difficult to stabilise the global quantities of the alternator. Ripples of numerical origin are observed on these quantities. The studies presented in this paper are intended toexplain these difficulties and show that these ripples are due to the famous backward Euler algorithm commonly used in this kind of model

Exploiting algebraic structures in probing security

The so-called $\omega$-encoding, introduced by Goudarzi, Joux and Rivain (Asiacrypt 2018), generalizes the commonly used arithmetic encoding. By using the additionnal structure of this encoding, they proposed a masked multiplication gadget (GJR) with quasilinear (randomness and operations) complexity. A follow-up contribution by Goudarzi, Prest, Rivain and Vergnaud in this line of research appeared in TCHES 2021. The authors revisited the aforementioned multiplication gadget (GPRV), and brought the IOS security notion for refresh gadgets to allow secure composition between probing secure gadgets. In this paper, we propose a follow up on GPRV, that is, a region-probing secure arithmetic circuit masked compiler. Our contribution stems from a single Lemma, linking algebra and probing security for a wide class of circuits, further taking advantage of the algebraic structure of $\omega$-encoding, and the extension field structure of the underlying field $\mathbb F$ that was so far left unexploited. On the theoretical side, we propose a security notion for $\boldsymbol{\omega}_d$-masked circuits which we call Reducible-To-Independent-K-linear (RTIK). When the number of shares $d$ is less than or equal to the degree $k$ of $\mathbb F$, RTIK circuits achieve region-probing security. Moreover, RTIK circuits may be composed naively and remain RTIK. We also propose a weaker version of IOS, which we call KIOS, for refresh gadgets. This notion allows to compose RTIK circuits with a randomness/security tradeoff compared to the naive composition. To substantiate our new definitions, we also provide examples of competitively efficient gadgets verifying the latter weaker security notions. Explicitly, we give 1) two refresh gadgets that use $d-1$ random field elements to refresh a length $d$ encoding, both of which are KIOS but not IOS, and 2) a multiplication gadget with bilinear multiplication complexity $d^{\log 3}$ and uses $d$ fresh random elements per run. Our compiler outperforms ISW asymptotically, but for our security proofs to hold, we do require that the number of shares $d$ is less than or equal to the degree of $\mathbb F$ as an extension, so that there is sufficient structure to exploit

Influence of the Outer Surface Layers of Crystals on the X-Ray Diffraction Intensity of Basal Reflections

International audienceThis study presents a mathematical formalism describing diffraction effects from periodic and mixed-layer minerals in which the outer surface layers of crystals differ from layers forming the core of the crystals. XRD patterns calculated for structure models of chlorite and irregular chlorite-smectites terminated on both sides of the crystals by either brucite-like or 2:1 layers show the strong influence that different outer surface layers make on the distribution of basal reflection intensities. Simulation of the experimental XRD patterns from two chlorite samples having different Fe-content shows that in these two samples the chlorite crystals were terminated by brucite-like layers on both sides. In contrast, crystals in a corrensite sample were terminated by water molecules and exchangeable cations. The nature of diffraction effects due to outer surface layers is discussed

Structure of Synthetic K-rich Birnessites Obtained by HighTemperature Decomposition of KMnO4. 2 Phase and Structural Heterogeneities

International audienceSynthetic K-rich birnessites (KBi) were prepared from the thermal decomposition of a fine-grained KMnO4 powder heated in air atmosphere at temperatures ranging from 2001000°C. The qualitative analysis of powder X-ray diffraction (XRD) patterns reveals a complex range of structural transformations from one metastable phase to the other, often through intermediate mixed-layer structures (MLSs). Phase and structural heterogeneities of KBi samples synthesized at 700°C, 800°C and 1000°C (referred to as KBi7, KBi8h and KBi10h) have been studied in details by chemical and thermal analysis and by simulation of the experimental powder XRD patterns. Two-layer orthogonal (2O), and hexagonal (2H) as well as three-layer rhombohedral (3R) polytypes were identified in these samples. The 2O structure consists of vacancy-free layers and their orthogonal symmetry is linked to the high content of layer Mn 3+ cations and to the unique azimuthal orientation of Mn3+ octahedra which are elongated because of Jahn-Teller distortion. In the 2H and 3R polytypes, the layers have a hexagonal symmetry as they contain only Mn 4+- and vacant octahedra. As a result, their interlayers have a heterogeneous cation composition, because of the migration of Mn 3+ from the layers to the interlayers. In addition to the periodic KBi polytypes, KBi7 and KBi8h contain MLSs in which layer pairs of the 2H polytype are interstratified at random with those of the 3R or of the 2O polytype. Interstratification of incommensurate 2O and 2H structural fragments leads to peculiar diffraction effects and represents a new type of structural disorder in birnessites. The increase of temperature from 700°C to 1000°C is associated with the replacement of 3R/2H, 2H, and 2O/2H mixed-layered structures by the more stable 2O polytype. KBi10h consists of a mixture of a minor 2H phase with three 2O varieties having slightly different layer unit-cell parameters. This phase heterogeneity results from the partial disorder in the orientation of Mn 3+ octahedra. The average structural formulae, K + 0.265Mn 3+ 0.145(Mn 4+ 0.82

Trozos de Real: de Freud al ultimísimo Lacan

En El ultimísimo Lacan (2013) Jacques-Alain Miller distingue el inconsciente freudiano y el lacaniano. El primero, cercano al primer Lacan, es un inconsciente del Otro; cuando al Otro se le suponía consistencia, era vector, marcaba una autopista para circular. El contacto con la clínica y los avances en la teoría conducen a Lacan a dar cuenta de las mutaciones en el discurso, en donde se evidencia el declive del padre, el Otro se pluraliza y se deduce el gran secreto del psicoanálisis: “no hay Otro del Otro” (Miller, 2013). Este movimiento epistémico conlleva consecuencias éticas, políticas y clínicas. (Párrafo extraído del texto a modo de resumen)Cátedra Libre Jacques Laca

Multi-scale characterization of monument limestones.

Among the parameters influencing stone deterioration, moisture and water movements through the pore network are essential. This communication presents differents methods to characterize stones and to determinate the water transfer properties. Results are analysed for two limestones having similar total porosity, but characterized by different pore networks. These different porous systems govern dissimilar water properties

Trozos de Real: de Freud al ultimísimo Lacan

En El ultimísimo Lacan (2013) Jacques-Alain Miller distingue el inconsciente freudiano y el lacaniano. El primero, cercano al primer Lacan, es un inconsciente del Otro; cuando al Otro se le suponía consistencia, era vector, marcaba una autopista para circular. El contacto con la clínica y los avances en la teoría conducen a Lacan a dar cuenta de las mutaciones en el discurso, en donde se evidencia el declive del padre, el Otro se pluraliza y se deduce el gran secreto del psicoanálisis: “no hay Otro del Otro” (Miller, 2013). Este movimiento epistémico conlleva consecuencias éticas, políticas y clínicas. (Párrafo extraído del texto a modo de resumen)Cátedra Libre Jacques Laca

Trozos de Real: de Freud al ultimísimo Lacan

En El ultimísimo Lacan (2013) Jacques-Alain Miller distingue el inconsciente freudiano y el lacaniano. El primero, cercano al primer Lacan, es un inconsciente del Otro; cuando al Otro se le suponía consistencia, era vector, marcaba una autopista para circular. El contacto con la clínica y los avances en la teoría conducen a Lacan a dar cuenta de las mutaciones en el discurso, en donde se evidencia el declive del padre, el Otro se pluraliza y se deduce el gran secreto del psicoanálisis: “no hay Otro del Otro” (Miller, 2013). Este movimiento epistémico conlleva consecuencias éticas, políticas y clínicas. (Párrafo extraído del texto a modo de resumen)Cátedra Libre Jacques Laca