11 resultados para Concrete-Filled steel tubular columns

em Consorci de Serveis Universitaris de Catalunya (CSUC), Spain


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The study was performed in the installations of OCAS, a Steel Research Centre of ArcelorMittal. Taking M32 steel (3.25%Si+0.9%Al) as the basis chemical composition and three different thicknesses (0.35, 0.5 and 0.65mm), different annealing conditions (temperature and time) have been applied in the laboratory simulator at St. Chély, France. The aim was to link annealing parameters, grain size and energy loss. It was determined the optimum annealing parameters to reach the lowest power losses for three different grades of non-oriented fully processed electrical steel. In addition, M250-50 samples having different magnetic behaviour (high and low losses) but the same grain size and texture, have been analyzed in terms of TEM observations of their precipitates, in the University of Marseille. The results reveal that a high amount of medium and big precipitates (&10 nm) worsen the magnetic properties of the material. The small precipitates (&10nm) do not have a strong influence on the magnetic properties. The presence of precipitates can have a great influence on the power losses and further work is clearly necessary.

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The influence of chemistry and soaking temperature (maximal temperature of the continuous annealing) on the final properties of non-oriented electrical steels has been studied. With this objective two different studies have been performed. First the Mn, Ni and Cr content of a low loss electrical steel composition has been modified. An intermediate content and a high content of each element has been added in order to study the influence of this components on the magnetic looses, grain size and texture. Secondly the influence of the soaking temperature on magnetic properties, grain size and oxidation in four grades of non-oriented electrical steels (Steel A, B, C and D) was studied.

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Piped water is used to remove hydration heat from concrete blocks during construction. In this paper we develop an approximate model for this process. The problem reduces to solving a one-dimensional heat equation in the concrete, coupled with a first order differential equation for the water temperature. Numerical results are presented and the effect of varying model parameters shown. An analytical solution is also provided for a steady-state constant heat generationmodel. This helps highlight the dependence on certain parameters and can therefore provide an aid in the design of cooling systems.

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Introducció: El bypass gàstric en Y de Roux laparoscòpic (BGYRL) és la tècnica quirúrgica d’elecció per al tractament de l’obesitat mòrbida. La gastrectomia tubular laparoscòpica (GTL) és una tècnica bariàtrica restrictiva amb resultats molt prometedors en relació a la pèrdua de pes, però se’n desconeixen els efectes metabòlics i endocrins. L’objectiu d’aquest estudi és l’avaluació de les diferències en la resposta del metabolisme de la glucosa i la secreció d’hormones intestinals entre ambdós procediments. Material i mètodes: Es va dissenyar un estudi prospectiu i aleatoritzat per la realització del BGYRL i la GTL, ambdós realitzats via laparoscòpica. Totes les pacients es varen avaluar abans, i als 3 i 12 mesos de la intervenció. Se’ls va prendre una mostra de sang venosa després d’un dejuni de 12 hores i als 10 i 60 minuts després de la ingesta d’Ensure® 420 kcal per realitzar les determinacions dels nivells plasmàtics de glucosa, insulina, grelina, leptina, pèptid relacionat amb glucagó (GLP-1), pèptid YY (PYY) i polipèptid pancreàtic (PP). Resultats: Es varen incloure 15 pacients (totes de gènere femení, edat mitja de 48±9 anys, IMC de 44±2.7 kg/m2 amlitat preoperatòria) dels quals 7 van ser aleatoritzats a BGYRL i 8 a GTL. No hi van haver diferències entre ambdós grups en edat, IMC preoperatori, classificació ASA i determinacions hormonals preoperatòries. Després de la cirurgia, s’observa un descens de la glicèmia i insulinèmia, amb una reducció de l´índex HOMA-IR en ambdós grups. Postoperatòriament, es detecta una disminución de les concentracions de la leptina en dejú i després de la ingesta, significativament menor en el grup de BGYRL. Mentre que els nivells de grelina en dejú només descendeixen de forma significativa en el grup de la GTL. Després de la ingesta es produeix una augment dels nivells de GLP-1, significativament major en el grup de BGYRL. Conclusions: Tan el BGYRL como la GTL s’associen a una significativa pèrdua de pes, encara que aquesta fou significativament superior en el BGYRL. Ambdós procediments han millorat notablement l’homeostasi de la glucosa. Només la GTL va rehuir els nivells de grelina tan en dejú com després de la ingesta, mentre que els nivells de GLP-1 i PYY s’elevaren després de la cirurgia, sense diferències estadísticament significatives entre ambdues tècniques.

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La cirurgia de l’obesitat suposa una eina dins de l’arsenal terapèutic dels pacients afectes d’obesitat mòrbida. La gastrectomia vertical s’ha popularitzat com a tècnica i les noves tecnologies com la laparoscòpia s’utilitzen de forma habitual. Més recentment la robòtica s’utilitza en diferents àmbits i també s’està implementant en la cirurgia de l’obesitat. A fi de compara la gastrectomia vertical realitzada mitjançant laparoscòpia o robòtica es planteja el següent estudi. S’han comparat els pacients intervinguts de gastrectomia vertical laparoscòpica i robòtica en termes de complicacions intraoperatòries, morbimortalitat i resultats en el seguiment dels pacients. Els resultats són satisfactoris en el sentit que es demostra que la tecnologia robòtica aporta els mateixos resultats en termes de complicacions intra y perioperatòries. Tanmateix es demostra que l’evolució ponderal dels pacients intervinguts de gastrectomia vertical amb tecnologia robòtica es igual a aquells intervinguts de manera tradicional. Així, es conclou que la tecnologia robòtica es una eina en ple desenvolupament que ha demostrat ser eficient, segura y eficaç per al tractament de la Obesitat Mòrbida mitjançant la Gastrectomia vertical.

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By using suitable parameters, we present a uni¯ed aproach for describing four methods for representing categorical data in a contingency table. These methods include:correspondence analysis (CA), the alternative approach using Hellinger distance (HD),the log-ratio (LR) alternative, which is appropriate for compositional data, and theso-called non-symmetrical correspondence analysis (NSCA). We then make an appropriate comparison among these four methods and some illustrative examples are given.Some approaches based on cumulative frequencies are also linked and studied usingmatrices.Key words: Correspondence analysis, Hellinger distance, Non-symmetrical correspondence analysis, log-ratio analysis, Taguchi inertia

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PRECON S.A is a manufacturing company dedicated to produce prefabricatedconcrete parts to several industries as rail transportation andagricultural industries.Recently, PRECON signed a contract with RENFE,the Spanish Nnational Rail Transportation Company to manufacturepre-stressed concrete sleepers for siding of the new railways of the highspeed train AVE. The scheduling problem associated with the manufacturingprocess of the sleepers is very complex since it involves severalconstraints and objectives. The constraints are related with productioncapacity, the quantity of available moulds, satisfying demand and otheroperational constraints. The two main objectives are related withmaximizing the usage of the manufacturing resources and minimizing themoulds movements. We developed a deterministic crowding genetic algorithmfor this multiobjective problem. The algorithm has proved to be a powerfuland flexible tool to solve the large-scale instance of this complex realscheduling problem.

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Capital intensive industries in specialized niches of production have constituted solid ground for family firms in Spain , as evidenced by the experience of the iron and steel wire industries between 1870 and 2000. The embeddedness of these firms in their local and regional environments have allowed the creation of networks that, together with favourable institutional conditions, significantly explain the dominance of family entrepreneurship in iron and steel wire manufacturing in Spain, until the end of the 20 th century. Dominance of family firms at the regional level has not been not an obstacle for innovation in wire manufacturing in Spain, which has taken place even when institutional conditions blocked innovation and traditional networking. Therefore, economic theories about the difficulties dynastic family firms may have to perform appropriately in science-based industries must be questioned

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The aim of this article is to show how, throughout M. A. Riera's poetry, an evident anti-metaphysical sensibility can be easily detected, which in its turn makes the poet to praise concrete person's skin, flesh and bodies, thus avoiding any personal Platonic or idealistic experience of human love. In the author's opinion, an accurate reading of his poems makes us discover Plato and Platonism as one of the great responsible thinkers for the contempt of carnal love, which has been undoubtedly the origin of a real human pain as a result of denying the somatic side of eros.

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Capital intensive industries in specialized niches of production have constituted solid ground for family firms in Spain , as evidenced by the experience of the iron and steel wire industries between 1870 and 2000. The embeddedness of these firms in their local and regional environments have allowed the creation of networks that, together with favourable institutional conditions, significantly explain the dominance of family entrepreneurship in iron and steel wire manufacturing in Spain, until the end of the 20 th century. Dominance of family firms at the regional level has not been not an obstacle for innovation in wire manufacturing in Spain, which has taken place even when institutional conditions blocked innovation and traditional networking. Therefore, economic theories about the difficulties dynastic family firms may have to perform appropriately in science-based industries must be questioned

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New methodologies for the analysis of volatile compoundsusing needle traps. Applications to breath, atmospheric andwater analysis. A new preconcentration technique has been developed for the analysis of volatile compounds based on the use of needle traps. These traps are based on stainless steel needles filled with one or more adsorbents, which allows the preconcentration of the anilities inside the trap by passing a gas flow through the needle. The parameters affecting the sorption/desorption process have been assessed (e.g. needle and liner dimensions, injector temperature, split less time, memory effects, and stability inside the needle). For liquid samples, four different sampling methodologies were studied, including passive and active sampling methods. The best results, considering the simplicity and sensitivity, are obtained by sampling the headspace volume using various cycles of a small and fix volume. Once the best conditions of analysis have been found, the method has been validated for gas and liquid samples. The results obtained show that needle traps are a good analytical methodology for the analysis of breath, environmental and liquid samples