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An a posteriori error analysis for an augmented discontinuous Galerkin method applied to Stokes problem
No full textThis paper deals with the a posteriori error analysis for an augmented mixed discontinuous formulation for the stationary Stokes problem. By considering an appropriate auxiliary problem, we derive an a posteriori error estimator. We prove that this estimator is reliable and locally efficient, and consists of just five residual terms. Numerical experiments confirm the theoretical properties of the augmented discontinuous scheme as well as of the estimator. They also show the capability of the corresponding adaptive algorithm to localize the singularities and the large stress regions of the solution
Uplift-hypoplastic macroelement model for shallow foundations in sand under cyclic combined loading
No full textIn this work, a coupled macroelement model for shallow foundations under cyclic loading has been developed. Coupling a hypoplastic constitutive model with an uplift plasticity model and a Mohr-Coulomb interface model can substantially improve the prediction of the foundation response. The yield surface adopted in this work is an ellipsoid and the flow rule can be chosen associated or non-associated. The couplings are achieved by introducing new variables that control the dominance of one model on the total response. Initial validation is carried out against numerical FEM simulations for shallow foundations in loose and dense sand subjected to monotonic and symmetric cyclic loading. Further validation against experimental data is performed by comparing the results obtained from caisson foundations in loose and dense sand subjected to non-symmetric and symmetric cyclic loading. The proposed macroelement model shows satisfactory results because it captures not only the limit loads, loading and unloading stiffness of load-displacement curves, but also complex cyclic settlement variations, in particular foundation uplift
Evolutionary transitions of decapod crustaceans to non-marine, polar, and deep-sea environments: Developmental, physiological and biochemical adaptations
No full textIn this brief, non-exhaustive essay, we review major adaptive changes in reproductive and developmental traits of decapod crustaceans, which have passed through evolutionary transitions from ancestral life in coastal marine environments to brackish, limnic, polar, or deep-sea habitats. Two major approaches can be recognised in studies of life-history evolution, focussing on: (1) developmental changes in adaptive physiological or biochemical traits of successive ontogenetic stages, comparing, for instance, osmoregulatory capabilities in larvae, juveniles, and adults (“ontogeny of adaptations” perspective); (2) adaptive changes in the modes of reproduction and development, e.g., enhanced maternal energy investment in egg production, abbreviated, non-feeding larval development (“adaptations in ontogeny”). Using both scientific approaches, Christoph D. Schubart has significantly contributed to our understanding of evolutionary transitions in crustaceans. In our essay, we pay particular attention to the significance of nutritional selection factors in relation to presumably adaptive developmental, physiological, and biochemical traits in different life-history stages. In this context, we highlight the key roles of lipids and carotenoid pigments, in particular of essential polyunsaturated fatty acids (PUFAs) and astaxanthin. While PUFAs and other lipid compounds have received wide scientific attention, we propose that future studies should further analyse also the potential role of astaxanthin and other essential carotenoids
Weights for moments’ geometrical localization: A canonical isomorphism
Get PDFThis paper deals with high order Whitney forms. We define a canonical isomorphism between two sets of degrees of freedom. This allows to geometrically localize the classical degrees of freedom, the moments, over the elements of a simplicial mesh. With such a localization, it is thus possible to associate, even with moments, a graph structure relating a field with its potential
Equal-order finite element method for the Stokes equations with variable viscosity
No full textIn this brief note, we extend the initial investigation proposed in John et al. (2016) to study the Stokes equations with variable viscosity considering a stabilized finite element scheme based on equal order polynomials for approximating the velocity and the pressure. We establish optimal a priori error estimates for this new stabilized scheme, which are further confirmed by numerical tests. Moreover, these tests show a weak viscosity dependence in the error bounds for different orders of magnitude between max and min
Práticas docentes vinculadas ao desenvolvimento de comunidades profissionais de aprendizage
Get PDFLa profesión docente es una actividad clave para el desarrollo de la sociedad; por lo tanto, el análisis de las condiciones laborales de los docentes se ha convertido en un tema de gran importancia debido a los desafíos e implicancias que debe enfrentar el profesorado. Un factor relevante que permita dar respuesta a las múltiples demandas requiere que el profesorado pueda avanzar en la conformación de prácticas multidisciplinarias, así como la disposición para el trabajo colaborativo. En este artículo de investigación se analiza la cultura de trabajo colaborativo docente, considerando las dimensiones que son identificadas como relevantes para promocionar una cultura escolar que promueve el desarrollo de una comunidad profesional de aprendizaje (CPA). De esta forma, se utiliza una estrategia metodológica mixta donde se registra información sobre prácticas pedagógicas vinculadas al desarrollo de una cultura de trabajo colaborativo y los desafíos que el profesorado identifica para la implementación de una cpa en sus establecimientos escolares. 52 docentes de 16 establecimientos de educación secundaria participaron en el estudio. Con base en las seis dimensiones que caracterizan el desarrollo de una cultura escolar colaborativa, los resultados evidencian diferencias en la implementación de prácticas pedagógicas que promueven una cultura escolar tradicional o vinculada a una CPA. De la misma manera, se identificaron diferencias entre la percepción de los docentes y miembros del equipo directivo. Finalmente, los resultados de esta investigación pueden ser de gran utilidad para la toma de decisiones que impacten en la cultura organizacional y que permitan avanzar hacia la conformación de una CPA efectiva.
Guest editorial: Computer science and information systems applied to management, innovation and sustainability
Get PDFPhotovoltaic sizing assessment for microgrid communities under load shifting constraints and endogenous electricity prices: A Stackelberg approach
No full textRenewable energy resources are crucial for decarbonizing the energy sector. Distributed energy resources, such as renewable generation by microgrids, aid the transition to net-zero systems. As microgrids proliferate, renewable generation often exceeds self-supply capacities, necessitating either the sale of excess electricity or the implementation of demand-response strategies. The optimal approach for microgrids (selling or shifting demand) hinges on electricity prices. This article examines the interplay between microgrids, demand response, photovoltaic investments, and pricing mechanisms. A novel Stackelberg model is proposed to minimize microgrid investment and operational costs. The upper-level problem determines energy community investments and demand response levels based on electricity prices, while the lower-level problem addresses market dispatch and endogenous pricing for microgrids. Case studies with varying battery storage levels, demand response limits, and pricing mechanisms are conducted. The research results illustrate the responsiveness of market transactions to supply conditions and pricing. Key findings show that microgrid flexibility in demand response reduces grid dependency, prompting significant investments in solar energy and battery storage, driven by economic incentives, especially under spot market conditions. Investments in solar energy more than double when microgrids trade energy at spot prices compared to flat prices
Teacher identity in the initial training of science educators: An approach from scientific culture
Get PDFEsta investigación identifica y caracteriza elementos epistemológicos didácticos que tributan a la Identidad de Docente de ciencias naturales en formación inicial en el marco de la cultura científica. Se levantan datos desde las narrativas de 22 estudiantes de carreras de pedagogía en ciencias naturales de cuatro universidades en tres regiones de la zona centro-sur de Chile, empleando para ello Teoría Fundamentada Constructivista. Los hallazgos exponen 87 códigos agrupados en 13 categorías, donde distinguen en base a su coocurrencia las categorías como Roles de docente en la enseñanza de las ciencias e Identidad y ethos, que junto a datos relacionados a la postura sobre las ciencias naturales y su didáctica sugieren el predominio de visiones asociadas a la réplica de modelos tradicionales de enseñanza alejadas de posturas críticas, contextualizadas y políticas en el futuro profesorado de ciencias. La identidad docente de los informantes se fundamenta por una cultura científica que transita por lo contextual, pero qué no alcanza a superar elementos epistemológicos y didácticos históricamente cuestionados en la enseñanza de las ciencias. Se sugiere avanzar en el desarrollo de espacios formativos contextualizados y territoriales para formar docentes sensibles y conscientes de su rol activista