A consistent approximation of the total perimeter functional for topology optimization algorithms

This article revolves around the total perimeter functional, one particular version of the perimeter of a shape O contained in a fixed computational domain D measuring the total area of its boundary ¿O, as opposed to its relative perimeter, which only takes into account the regions of ¿O strictly inside D. We construct and analyze approximate versions of the total perimeter which make sense for general “density functions” u, as generalized characteristic functions of shapes. Their use in the context of density-based topology optimization is particularly convenient insofar as they do not involve the gradient of the optimized function u. Two different constructions are proposed: while the first one involves the convolution of the function u with a smooth mollifier, the second one is based on the resolution of an elliptic boundary-value problem featuring Robin boundary conditions. The “consistency” of these approximations with the original notion of total perimeter is appraised from various points of view. At first, we prove the pointwise convergence of our approximate functionals, then the convergence of their derivatives, as the level of smoothing tends to 0, when the considered density function u is the characteristic function of a “regular enough” shape O ¿ D. Then, we focus on the G-convergence of the second type of approximate total perimeter functional, that based on elliptic regularization. Several numerical examples are eventually presented in two and three space dimensions to validate our theoretical findings and demonstrate the efficiency of the proposed functionals in the context of structural optimization.This work is partly supported by the project ANR-18-CE40-0013 SHAPO, financed by the French Agence Nationale de la Recherche (ANR). S.A. benefitted from the support of the chair "Modeling advanced polymers for innovative material solutions" led by the École Polytechnique and the Fondation de l'École Polytechnique, and sponsored by Arkema.Postprint (published version

Del bol al plat. Canvis en els hàbits alimentaris i diferències en els estils de consum al curs inferior de l’Ebre (SS. VII-VI ANE)

The ceramic assemblages of the lower Ebro bassin show in the First Iron Age a clear expansion and diversification of crockery services. These modifications include the presence of carinated outset lip dishes, a type of dish which usually is upon a high foot, a trait that gives it a very characteristic aspect among the instruments of food consumption. The appearance of this type of dishes is related both to the practice of new food habits as with the first differences in consumption styles, a fact which forces us to assess not only their use in domestic consumption practices, but also its possible use in certain exceptional celebrations

Estudios sefardíes dedicados a la memoria de Iacob M. Hassán (ź"l)

Elena Romero y Aitor García Moreno son los editores de este volumen.[EN] This work aims to honour Iacob. M. Hassán, who set up, promoted, and for decades maintained, the CSIC's School of Sephardic studies (Escuela de Estudios Sefardíes) in Madrid. It comprises a collection of articles on the Jews in the medieval Spanish kingdoms, along with other articles on a wide variety of language issues, and the study and publication of literary works produced or handed down by the Sephardim of the Balkans and Morocco between the sixteenth and the twentieth centuries, such as biblical commentaries and lexicons, liturgical poetry, rabbinic literature, biographies, folk tales, popular folk songs, ballads, and modern songs ... These studies also include an article by Iacob. M. Hassán published here for the first time in the form of a facsimile of his original typed manuscript. The work is preceded by a foreword and an unpublished text of one of his lectures, which contains a wealth of autobiographical information, as well as his views on the vicissitudes of Sephardic Studies as an academic discipline.[ES] Con esta obra se quiere honrar al creador, impulsor y mantenedor durante decenios de la llamada Escuela de Estudios Sefardíes del CSIC (Madrid). Se recogen en ella artículos relativos a los judíos en los reinos hispanos medievales, y otros dedicados a muy variados temas de lengua, y al estudio y edición de obras literarias producidas o transmitidas por los sefardíes de los Balcanes y de Marruecos entre el siglo XVI y el XX: comentarios y léxicos bíblicos, poesía litúrgica, literatura rabínica, biografías, cuentos tradicionales, coplas, romances, cancionero moderno, etc., etc. Entre los estudios se incluye además, como primicia, un artículo mecanografiado de Iacob. M. Hassán que se publica por primera vez en edición facsímil. La obra va precedida de un Prólogo y del texto inédito de una de sus conferencias, en la que aporta numerosos datos autobiográficos, así como su visión sobre los avatares de los Estudios Sefardíes como disciplina académica

Hot Vents Beneath an Icy Ocean: The Aurora Vent Field, Gakkel Ridge, Revealed

Evidence of hydrothermal venting on the ultra-slow spreading Gakkel Ridge in the Central Arctic Ocean has been available since 2001, with first visual evidence of black smokers on the Aurora Vent Field obtained in 2014. But it was not until 2021 that the first ever remotely operated vehicle (ROV) dives to hydrothermal vents under permanent ice cover in the Arctic were conducted, enabling the collection of vent fluids, rocks, microbes, and fauna. In this paper, we present the methods employed for deep-sea ROV operations under drifting ice. We also provide the first description of the Aurora Vent Field, which includes three actively venting black smokers and diffuse flow on the Aurora mound at ~3,888 m depth on the southern part of the Gakkel Ridge (82.5°N). The biological communities are dominated by a new species of cocculinid limpet, two small gastropods, and a melitid amphipod. The ongoing analyses of Aurora Vent Field samples will contribute to positioning the Gakkel Ridge hydrothermal vents in the global biogeographic puzzle of hydrothermal vents

Sepharadim/conversos and premodern Global Hispanism

Sepharadim participated in the Hispanic vernacular culture of the Iberian Peninsula. Even in the time of al-Andalus many spoke Hispano-Romance, and even their Hebrew literature belies a deep familiarity with and love of their native Hispano-Romance languages. However, since the early sixteenth century the vast majority of Sepharadim have never lived in the Hispanic world. Sepharadim lived not in Spanish colonies defined by Spanish conquest, but in a network of Mediterranean Jewish communities defined by diasporic values and institutions. By contrast, the conversos, those Sepharadim who converted to Catholicism, whether in Spain or later in Portugal, Italy, or the New World, lived mostly in Spanish Imperial lands, were officially Catholic, and spoke normative Castilian. Their connections, both real and imagined, with Sephardic cultural practice put them at risk of social marginalization, incarceration, even death. Some were devout Catholics whose heritage and family history doomed them to these outcomes. Not surprisingly, many Spanish and Portugese conversos sought refuge in lands outside of Spanish control where they might live openly as Jews. This exodus (1600s) from the lands formerly known as Sefarad led to a parallel Sephardic community of what conversos who re-embraced Judaism in Amsterdam and Italy by a generation of conversos trained in Spanish universities. The Sephardic/Converso cultural complex exceeds the boundaries of Spanish imperial geography, confuses Spanish, Portuguese, Catholic, and Jewish subjectivities, and defies traditional categories practiced in Hispanic studies, and are a unique example of the Global Hispanophone

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

A consistent relaxation of optimal design problems for coupling shape and topological derivatives

In this article, we introduce and analyze a general procedure for approximating a ‘black and white’ shape and topology optimization problem with a density optimization problem, allowing for the presence of ‘grayscale’ regions. Our construction relies on a regularizing operator for smearing the characteristic functions involved in the exact optimization problem, and on an interpolation scheme, which endows the intermediate density regions with fictitious material properties. Under mild hypotheses on the smoothing operator and on the interpolation scheme, we prove that the features of the approximate density optimization problem (material properties, objective function, etc.) converge to their exact counterparts as the smoothing parameter vanishes. In particular, the gradient of the approximate objective functional with respect to the density function converges to either the shape or the topological derivative of the exact objective. These results shed new light on the connections between these two different notions of sensitivities for functions of the domain, and they give rise to different numerical algorithms which are illustrated by several experimentsPeer Reviewe

Maximum generation power evaluation of variable frequency offshore wind farms when connected to a single power converter

High voltage direct current (HVDC) Variable frequency wind farm Offshore wind power a b s t r a c t The paper deals with the evaluation of power generated by variable and constant frequency offshore wind farms connected to a single large power converter. A methodology to analyze different wind speed scenarios and system electrical frequencies is presented and applied to a case study, where it is shown that he variable frequency wind farm concept (VF) with a single power converter obtains 92% of the total available power, obtained with individual power converters in each wind turbine (PC). The PC scheme needs multiple power converters implying drawbacks in terms of cost, maintenance and reliability. The VF scheme is also compared to a constant frequency scheme CF, and it is shown that a significant power increase of more than 20% can be obtained with VF. The case study considers a wind farm composed of four wind turbines based on synchronous generators