Converting DAE models to ODE models: application to reactive Rayleigh distillation

This paper illustrates the application of an index reduction method to some differential algebraic equations (DAE) modelling the reactive Rayleigh distillation. After two deflation steps, this DAE is converted to an equivalent first-order explicit ordinary differential equation (ODE). This ODE involves a reduced number of dependent variables, and some evaluations of implicit functions defined, either from the original algebraic constraints, or from the hidden ones. Consistent initial conditions are no longer to be computed; at the opposite of some other index reduction methods, which generate a drift-off effect, the algebraic constraints remain satisfied at any time; and, finally, the computational effort to solve the ODE may be less than the one associated to the original DAE

An innovative collaborative high-performance platform for simulation

This paper presents an innovative collaborative visualization platform for the simulation-based design applications. Following the scope and the main objectives, the general architecture based on the internet standard technologies is explained. Based on a multi-domain approach, several demonstrators are involved crossing interests of industrial and academic communities. Related to the field of process engineering, we adapt and deploy a web-based architecture research application on the targeted platform

Modèle de coopération entre calcul formel et calcul numérique pour la simulation et l'optimisation des systèmes

Après avoir étudié les collaborations établies aujourd'hui entre différents environnements de résolution de problèmes, le manuscrit propose un modèle de conception d'un système de calcul basé sur la coopération entre calcul formel et numérique. Cette coopération entre différents sous-systèmes de calcul est de type complémentaire : les rôles sont définis a priori. Suivant une démarche orientée modèle, le modèle de coopération est spécifié en UML 2.0 selon la vue structurelle et la vue comportementale. A partir du modèle conceptuel, nous définissons les règles de transformation pour produire le modèle d'implémentation spécifique de la "plate-forme" FORTRAN 90. Au vu des résultats d'études particulières en génie des procédés - la solvatation d'acides forts, et la distillation de Rayleigh- il apparaît que la démarche de calcul coopératif proposée : apporte plus d'expressivité lors de la modélisation; incite à modéliser les systèmes physiques à l'aide de fonctions, souvent implicites; permet la réutilisation de modèles par la composition et l'assemblage de fonctions; et apporte plus de fiabilité lors de la simulation, notamment grâce au calcul précis des dérivées des modèles. ABSTRACT : After investigating state-of-the-art collaborations between various environments aimed at system resolution, this paper presents a design model for a calculation system based on the co-operation of formal and numerical calculations. This co-operation between multiple sub-systems is complementary: the roles are defined a priori. Following an object-oriented approach, the model is specified via UML 2.0, in terms of the structural and behavioural views. From the conceptual model, we define the transformation rules required to create the implementation - specific model for the FORTRAN 90 platform. From the results witnessed within specific process engineering studies - namely the solvation of strong acids and Rayleigh's distillation - it can be seen that this co-operative approach: empowers us with an improved expressivity at the modelling stage; instigates physical modelling using (often implicit) functions; allows model re-use through function aggregation and assembly; and brings a greater reliability during simulation, notably as a result of the precise calculation of derivatives of the mode

An homotopy method for global optimization of continuous models

An original approach to global optimization of continuous models is introduced. It belongs to the class of homotopy continuation methods, but "only" requires non linear equation systems to be solved. Unconstrained and non-linearly constrained optimization problems are specified nearly the same way. They are solved by coupling a robust Newton formulation for under determinate systems and a heuristic estimating the global minimum value by means of the discrete Legendre-Fenchel biconjugate of the criterion. For the time being, the main drawback of the method is the too important number of function evaluations near by the global minimum. However, its success rate being very good on test problems, such as the global optimization of Lennard-Jones atomic clusters, it should be investigated further

Autopet Challenge 2023: nnUNet-based whole-body 3D PET-CT Tumour Segmentation

Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) combined with Computed Tomography (CT) scans are critical in oncology to the identification of solid tumours and the monitoring of their progression. However, precise and consistent lesion segmentation remains challenging, as manual segmentation is time-consuming and subject to intra- and inter-observer variability. Despite their promise, automated segmentation methods often struggle with false positive segmentation of regions of healthy metabolic activity, particularly when presented with such a complex range of tumours across the whole body. In this paper, we explore the application of the nnUNet to tumour segmentation of whole-body PET-CT scans and conduct different experiments on optimal training and post-processing strategies. Our best model obtains a Dice score of 69\% and a false negative and false positive volume of 6.27 and 5.78 mL respectively, on our internal test set. This model is submitted as part of the autoPET 2023 challenge. Our code is available at: https://github.com/anissa218/autopet\_nnune

Estética e Imperio. El sentido de belleza femenina en la construcción del archipiélago imperial estadounidense

This article examines the “sense of beauty” in the United States imperial archipelago, composed of the island territories of Cuba, Hawai`i, Philippines, and Puerto Rico, all acquired in 1898. The theoretical connection among these two elements –aesthetics and empire– is provided by a revision of the concepts “economy of colonial desire” and “complex of visuality.” This paper analyzes the most advanced visual technology of the late nineteenth century: the mass- produced, printed photograph. In particular, it focuses upon the representations of feminine beauty as found the illustrated “new-possessions” books which described recent island acquisitions of the United States. The connections between aesthetics and the forms of governance in each territory will also be elucidated.Este artículo examina el “sentido de belleza” en el archipiélago imperial estadounidense, compuesto de los territorios isleños de Cuba, Hawai`i, Filipinas y Puerto Rico, todos adquiridos en 1898. La conexión teórica entre estos dos elementos –estética e imperio– se establece mediante una revisión de los conceptos de “economía de deseo colonial” y el “complejo de visualidad”. Este artículo analiza la tecnología visual más avanzada del siglo diecinueve tardío: la fotografía impresa. En particular, se enfoca en las representaciones de belleza femenina en los libros ilustrados de las “nuevas posesiones” los cuales describían las adquisiciones recientes de los Estados Unidos. También, se dilucidarán las conexiones entre estética y las formas de gobernanza en cada territorio

Said, bhabha and the colonised subject

Homi K. Bhabha’s introduction to his collected essays, The Location of Culture, opens with an apprehension of the moment he is writing from as one marked by disorientation, with the ‘posts’ of postmodernism, postcolonialism and postfeminism on the one hand and the sense of restless movements, a moving back and forth, ‘here and there’, that has unhooked contemporary critical theory from fixed and primary organisational categories, and has produced constellations of ways of being that acknowledge “race, gender, generation, institutional location, geopolitical locale, sexual orientation”.1 The central proposition established in this opening is the argument that it is “theoretically innovative, and politically crucial, … to think beyond narratives of originary and initial subjectivities and to focus on those moments or processes that are produced in the articulation of cultural difference

Technological elites, the meritocracy, and postracial myths in Silicon Valley

Entre as modernas elites tecnológicas digitais, os mitos da meritocracia e da façanha intelectual são usados como marcadores de raça e gênero por uma supremacia branca masculina que consolida recursos de forma desproporcional em relação a pessoas não brancas, principalmente negros, latinos e indígenas. Os investimentos em mitos meritocráticos suprimem os questionamentos de racismo e discriminação, mesmo quando os produtos das elites digitais são infundidos com marcadores de raça, classe e gênero. As lutas históricas por inclusão social, política e econômica de negros, mulheres e outras classes desprotegidas têm implicado no reconhecimento da exclusão sistêmica, do trabalho forçado e da privação de direitos estruturais, além de compromissos com políticas públicas dos EUA, como as ações afirmativas, que foram igualmente fundamentais para reformas políticas voltadas para participação e oportunidades econômicas. A ascensão da tecnocracia digital tem sido, em muitos aspectos, antitética a esses esforços no sentido de reconhecer raça e gênero como fatores cruciais para inclusão e oportunidades tecnocráticas. Este artigo explora algumas das formas pelas quais os discursos das elites tecnocráticas do Vale do Silício reforçam os investimentos no pós racialismo como um pretexto para a re-consolidação do capital em oposição às políticas públicas que prometem acabar com práticas discriminatórias no mundo do trabalho. Por meio de uma análise cuidadosa do surgimento de empresas de tecnologias digitais e de uma discussão sobre como as elites tecnológicas trabalham para mascarar tudo, como inscrições algorítmicas e genéticas de raça incorporadas em seus produtos, mostramos como as elites digitais omitem a sua responsabilidade por suas reinscrições pós raciais de (in)visibilidades raciais. A partir do uso de análise histórica e crítica do discurso, o artigo revela como os mitos de uma meritocracia digital baseados em um “daltonismo racial” tecnocrático emergem como chave para a manutenção de exclusões de gênero e raça.Palavras-chave: Tecnologia. Raça. Gênero.Among modern digital technology elites, myths of meritocracy and intellectual prowess are used as racial and gender markers of white male supremacy that disproportionately consolidate resources away from people of color, particularly African Americans, Latino/as and Native Americans. Investments in meritocratic myths suppress interrogations of racism and discrimination even as the products of digital elites are infused with racial, class, and gender markers. Longstanding struggles for social, political, and economic inclusion for African Americans, women, and other legally protected classes have been predicated upon the recognition of systemic exclusion, forced labor, and structural disenfranchisement, and commitments to US public policies like affirmative action have, likewise, been fundamental to political reforms geared to economic opportunity and participation. The rise of the digital technocracy has, in many ways, been antithetical to these sustained efforts to recognize race and gender as salient factors structuring technocratic opportunity and inclusion. This paper explores some of the ways in which discourses of Silicon Valley technocratic elites bolster investments in post-racialism as a pretext for re-consolidations of capital, in opposition to public policy commitments to end discriminatory labor practices. Through a careful analysis of the rise of digital technology companies, and a discussion of how technology elites work to mask everything from algorithmic to genetic inscriptions of race embedded in their products, we show how digital elites elide responsibility for their post-racial re-inscriptions of racial visibilities (and invisibilities). Using historical and critical discourse analysis, the paper reveals how myths of a digital meritocracy premised on a technocratic colorblindness emerge key to perpetuating gender and racial exclusions.Keywords: Technology. Race. Gender

Modelisation du fonctionnement d'un capteur solaire couple a une pompe a chaleur

SIGLECNRS TD Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc