High-performance model reduction procedures in multiscale simulations

Technological progress and discovery and mastery of increasingly sophisticated structural materials have been inexorably tied together since the dawn of history. In the present era — the so-called Space Age —-, the prevailing trend is to design and create new materials, or improved existing ones, by meticulously altering and controlling structural features that span across all types of length scales: the ultimate aim is to achieve macroscopic proper- ties (yield strength, ductility, toughness, fatigue limit . . . ) tailored to given practical applications. Research efforts in this aspect range in complexity from the creation of structures at the scale of single atoms and molecules — the realm of nanotechnology —, to the more mundane, to the average civil and mechanical engineers, development of structural materials by changing the composition, distribution, size and topology of their constituents at the microscopic/mesoscopic level (composite materials and porous metals, for instance).Postprint (published version

Multi-scale (FE2) analysis of material failure in cement/aggregate-type composite structures

The work propases a FP multiscale approach to computational modeling of material failure in concreteMlike structures, made of cement/aggregate-type composite materials. Keeping the approach in a classical homogenization setting, a multiscale model is proposed, which naturally provides a microscopic length-scale to be exported to the macrostructure. There, this length scale is used as regularization parameter in the context of the Continuum Strong Discontinuity Approach to material failure, and finite elements with embedded strong discontinuities (E~ FE M). The resulting technique allows robust modeling of crack propagation at the structural scale, accounting for the mesostructure morphology, supplies proper energy dissipation and solutions independent of the finite element and RVE sizes. Application toa number of examples, in the range from light-aggregate concrete to regular concrete, shows the potentiality of the method.Postprint (published version

Reduced order modeling strategies for computational multiscale fracture

The paper proposes some new computational strategies for affordably solving multiscale fracture problems through a FE2 approach. To take into account the mechanical effects induced by fracture at the microstructure level the Representative Volume Element (RVE), assumed constituted by an elastic matrix and inclusions, is endowed with a large set of cohesive softening bands providing a good representation of the possible microstructure crack paths. The RVE response is then homogenized in accordance with a model previously developed by the authors and upscaled to the macro-scale level as a continuum stress–strain constitutive equation, which is then used in a conventional framework of a finite element modeling of propagating fracture. For reduced order modeling (ROM) purposes, the RVE boundary value problem is first formulated in displacement fluctuations and used, via the Proper Orthogonal Decomposition (POD), to find a low-dimension space for solving the reduced problem. A domain separation strategy is proposed as a first technique for model order reduction: unconventionally, the low-dimension space is spanned by a basis in terms of fluctuating strains, as primitive kinematic variables, instead of the conventional formulation in terms of displacement fluctuations. The RVE spatial domain is then decomposed into a regular domain (made of the matrix and the inclusions) and a singular domain (constituted by cohesive bands), the required RVE boundary conditions are rephrased in terms of strains and imposed via Lagrange multipliers in the corresponding variational problem. Specific low-dimensional strain basis is then derived, independently for each domain, via the POD of the corresponding strain snapshots. Next step consists of developing a hyper-reduced model (HPROM). It is based on a second proposed technique, the Reduced Optimal Quadrature (ROQ) which, again unconventionally, is determined through optimization of the numerical integration of the primitive saddle-point problem arising from the RVE problem, rather than its derived variational equations, and substitutes the conventional Gauss quadrature. The ROQ utilizes a very reduced number of, optimally placed, sampling points, the corresponding weights and placements being evaluated through a greedy algorithm. The resulting low-dimensional and reduced-quadrature variational problem translates into very relevant savings on the computational cost and high computational speed-ups. Particular attention is additionally given to numerical tests and performance evaluations of the new hyper-reduced methodology, by “a-priori” and “a-posteriori” error assessments. Moreover, for the purposes of validation of the present techniques, a real structural problem exhibiting propagating fracture at two-scales is modeled on the basis of the strain injection-based multiscale approach previously developed by the authors. The performance of the proposed strategy, in terms of speed-up vs. error, is deeply analyzed and reported.Peer ReviewedPostprint (published version

Natural ester fluids applications in transformers as a sustainable dielectric and coolant

New requirements for a better sustainable energy policy around the world is easy to observe, many projects in sustainable energy are developed wherein the academia works together the authorities and commercial firms such as electrical grid utilities. In distribution transformers one of the suggested solutions is to replace mineral oils used as dielectric and coolant for natural ester fluids, they provide improved technical properties making them a safe substitute of mineral oil. Natural esters are based on clean technology in order to guarantee requirements from utilities. The main goal of the present paper is to present a technical-economic analysis obtained from five years of applications of oil-immersed transformers using natural ester fluids in Colombia. The methodology considers forty-four oil-immersed distribution Transformers, a half use mineral oil and the other side use natural ester, operating under the same load regime. Results evidenced the feasibility of implementing this technology because the costs are very similar and the reduction of risks and environmental impact is considerable. © 2019 Author(s)

Extração de pectina obtida da casca do limão persa (Citrus latifolia Tanaka): Extraction of pectin obtained from Persian lime peel (Citrus latifolia Tanaka)

La extracción de pectina a partir de la cáscara de cítricos es una alternativa para generar valor agregado a estos residuos y disminuir los impactos al medio ambiente. El objetivo de la investigación fue extraer pectina de cáscara de limón persa (PCEI y PCEL) y compararla con pectina comercial cítrica pura (PCCP). La cáscara se obtuvo de una empresa extractora de jugos y de frutos de tercera calidad adquiridos en el mercado municipal de Martínez de la Torre, Veracruz. Sé determinó el rendimiento de pectina extraída (% de Rend), peso equivalente (PE), grado de esterificación (%GE), contenido total de ácido anhidro galacturónico (%AAG), contenido de metoxilo (%MeO) y acidez libre (AL). Se realizó un análisis de varianza (ANOVA) de un solo factor con tres repeticiones y comparación de medias (Tukey, ). El % de Rend de la PCEL fue de 42.2% mostrando diferencia significativa respecto de la PCEI con un valor de 48.7%. La PCEL presento significativamente el menor peso equivalente (1094.7 mg meq-1). El porcentaje de metoxilo y ácido anhidro galacturónico no presentaron diferencia significativa obteniendo valores promedio de 9.06 % y 65.5 %, respectivamente. La PCEL presento un grado de esterificación (74.6±1.6 %) significativamente menor a la PCCP (80.6±3.5 %). La PCEL presento significativamente una mayor AL con respecto a PCEI y PCCP. Se obtuvo pectina de alto metoxilo y gelificación lenta de la cáscara del limón persa con características similares a la PCCP, apta para uso y aplicación en la industria alimentaria

Phytotoxicity evaluation of sesquiterpene lactones and diterpenes from species of the Decachaeta, Salvia and Podachaenium genera

Decachaeta, Salvia and Podachaenium genera are known for their wide variety of biological activities. Synthetic herbicides have caused a variety of environmental and resistance problems. Natural products represent an important alternative to combat such issues. Sesquiterpene lactones and diterpenes are families of bioactive natural products for which a range of activities have been described. The bioactivities of nine sesquiterpene lactones, eight heliangolides, one guaianolide and twenty two diterpenes isolated from species of the Decachaeta, Salvia and Podachaenium genera were tested by applying a methodical procedure that involves assays of compounds on etiolated wheat coleoptiles (Triticum aestivum), Standard Target Species (STS) and two important weeds (barnyardgrass and brachiaria). The results clearly show that all of the sesquiterpene lactones studied were active on coleoptiles. In addition, six lactones were phytotoxic on both STS and weeds, meaning that these compounds could be used in the development of natural herbicide models

Transcriptomics and molecular evolutionary rate analysis of the bladderwort (Utricularia), a carnivorous plant with a minimal genome

<p>Abstract</p> <p>Background</p> <p>The carnivorous plant <it>Utricularia gibba </it>(bladderwort) is remarkable in having a minute genome, which at ca. 80 megabases is approximately half that of <it>Arabidopsis</it>. Bladderworts show an incredible diversity of forms surrounding a defined theme: tiny, bladder-like suction traps on terrestrial, epiphytic, or aquatic plants with a diversity of unusual vegetative forms. <it>Utricularia </it>plants, which are rootless, are also anomalous in physiological features (respiration and carbon distribution), and highly enhanced molecular evolutionary rates in chloroplast, mitochondrial and nuclear ribosomal sequences. Despite great interest in the genus, no genomic resources exist for <it>Utricularia</it>, and the substitution rate increase has received limited study.</p> <p>Results</p> <p>Here we describe the sequencing and analysis of the <it>Utricularia gibba </it>transcriptome. Three different organs were surveyed, the traps, the vegetative shoot bodies, and the inflorescence stems. We also examined the bladderwort transcriptome under diverse stress conditions. We detail aspects of functional classification, tissue similarity, nitrogen and phosphorus metabolism, respiration, DNA repair, and detoxification of reactive oxygen species (ROS). Long contigs of plastid and mitochondrial genomes, as well as sequences for 100 individual nuclear genes, were compared with those of other plants to better establish information on molecular evolutionary rates.</p> <p>Conclusion</p> <p>The <it>Utricularia </it>transcriptome provides a detailed genomic window into processes occurring in a carnivorous plant. It contains a deep representation of the complex metabolic pathways that characterize a putative minimal plant genome, permitting its use as a source of genomic information to explore the structural, functional, and evolutionary diversity of the genus. Vegetative shoots and traps are the most similar organs by functional classification of their transcriptome, the traps expressing hydrolytic enzymes for prey digestion that were previously thought to be encoded by bacteria. Supporting physiological data, global gene expression analysis shows that traps significantly over-express genes involved in respiration and that phosphate uptake might occur mainly in traps, whereas nitrogen uptake could in part take place in vegetative parts. Expression of DNA repair and ROS detoxification enzymes may be indicative of a response to increased respiration. Finally, evidence from the bladderwort transcriptome, direct measurement of ROS <it>in situ</it>, and cross-species comparisons of organellar genomes and multiple nuclear genes supports the hypothesis that increased nucleotide substitution rates throughout the plant may be due to the mutagenic action of amplified ROS production.</p

Sensitization to Platanus Occidentalis Tree and Ricinus Communis Weed Pollen in Northern Mexico

El polen Platanus occidentalis (Po) y Ricinus communis (Rc) se capturaron con un Hirst volumétrico (Burkard Manufacturing Co.) en Monterrey. Evaluamos su ensibilización prevalencia para incluir estos alérgenos en nuestras pruebas rutinarias de punción cutánea (SPT