Análisis de los criterios de construcción y diseño para minimizar el riesgo de figuración de particiones interiores por excesiva deformabilidad de la estructura horizontal

La Cátedra de Edificación de la Universidad Politécnica de Madrid, en colaboración con el instituto Técnico de Materiales y Construcciones (iNTEMAC), está llevando a cabo una investigación sobre las distintas variables que pueden influir en ia aparición de fisuras en tabiques y cerramientos de edificios con estructura de hormigón armado debido a la flecha vertical de la estructura horizontal, problema que aún no ha sido resuelto de forma totalmente satisfactoria con los criterios de las normativas, en particular las vigentes en España. De un primer análisis de de los casos analizados se deduce la importante influencia de otras variables no contempladas por la normativa en la aparición de daños y en la intensidad de estos. En la presente comunicación se exponen los principales resultados obtenidos en dichos análisi

Disseny i fabricació de pròtesis amb impressores 3D

En aquest treball s’estudia la viabilitat i efectivitat d’utilitzar com a aparell mèdic una impressora 3D, per tal d’imprimir pròtesis –comparativament amb les convencionals- molt més econòmiques per a infants, en llocs on no es tenen els recursos suficients per accedir a pròtesis més cares. La pròtesi ha d’estar fabricada majoritàriament amb impressió 3D, i el que no es pugui imprimir, ha de ser materials molt comuns disponibles en qualsevol lloc, com ara cordons o cargols, fins i tot el primer podria substituir-se per corda o altre material assimilable. Per començar, en el treball es fa una breu introducció a la impressió 3D, així com una cerca de les alternatives existents, i, posteriorment, es passa a dissenyar la pròtesi, en aquest cas de cama per sota del genoll, per tal de trobar el disseny que compleixi les especificacions tècniques requerides i que sigui fàcil d’imprimir i de muntar. El següent pas del treball és un estudi per tal que el disseny compleixi els requeriments mecànics imposats per la normativa ISO, ja que tot i no ser una pròtesi comercial, sí que és una pròtesi funcional i per això ha de complir la normativa com qualsevol altra pròtesi. Això es fa utilitzant el mètode d’elements finits amb ANSYS, imposant les condicions de la normativa i buscant els punts crítics per on pot fallar la pròtesi per tal de modificar-la i així complir-la. Un cop s’ha triat el disseny es fa una impressió de la pròtesi per tal de comprovar que el seu funcionament és correcte i que no hi ha cap error de disseny, i es fa una prova de subjecció a la cama per tal de comprovar com aguantarà la pròtesi un cop l’infant la tingui posada. Per últim es crea una base de dades on es poden baixar els arxius de les pròtesis ordenats segons la mida del peu, l’altura fins al genoll i el perímetre del panxell, per tal que es seleccioni el més adequat per l’infant en qüestió i es procedeixi a la seva impressió

Electrocoagulation-Adsorption to remove anionic and cationic dyes from aqueous solution by PV-Energy

The cationic dye malachite green (MG) and the anionic dye Remazol yellow (RY) were removed from aqueous solutions using electrocoagulation-adsorption processes. Batch and continuous electrocoagulation procedures were performed and compared. Carbonaceous materials obtained from industrial sewage sludge and commercial activated carbons were used to adsorb dyes from aqueous solutions in column systems with a 96–98% removal efficiency. The continuous electrocoagulation-adsorption system was more efficient for removing dyes than electrocoagulation alone. The thermodynamic parameters suggested the feasibility of the process and indicated that the adsorption was spontaneous and endothermic (Δ = 0.037 and −0.009 for MG and RY, resp.). The Δ value further indicated that the adsorption process was spontaneous (−6.31 and −10.48; = 303 K). The kinetic electrocoagulation results and fixed-bed adsorption results were adequately described using a first-order model and a Bohart-Adams model, respectively. The adsorption capacities of the batch and column studies differed for each dye, and both adsorbent materials showed a high affinity for the cationic dye.Thus, the results presented in this work indicate that a continuous electrocoagulation-adsorption system can effectively remove this type of pollutant from water. The morphology and elements present in the sludge and adsorbents before and after dye adsorption were characterized using SEM-EDS and FT-IR

Sourced Friedmann equations with holographic energy density

We reexamine cosmological applications of the holographic energy density in the framework of sourced Friedmann equations. This framework is suitable because it can accommodate a macroscopic interaction between holographic and ordinary matter naturally. In the case that the holographic energy density decays into dust matter, we propose a microscopic mechanism to generate an accelerating phase. Actually, the cosmic anti-friction arisen from the decay process induces acceleration. For examples, we introduce two IR cutoffs of Hubble horizon and future event horizon to test this framework. As a result, it is shown that the equations of state for the holographic energy density are determined to be the same negative constants as those for the dust matter.Comment: 11 pages, final version to appear in PL

Equation of state for an interacting holographic dark energy model

We investigate a model of the interacting holographic dark energy with cold dark matter (CDM). If the holographic energy density decays into CDM, we find two types of the effective equation of state. In this case we have to use the effective equations of state ($\omega^{\rm eff}_{\rm \Lambda}$) instead of the equation of state ($\omega_{\rm \Lambda})$. For a fixed ratio of two energy densities, their effective equations of state are given by the same negative constant. Actually, the cosmic anti-friction arisen from the vacuum decay process may induce the acceleration with $\omega^{\rm eff}_{\rm \Lambda}<-1/3$. For a variable ratio, their effective equations of state are slightly different, but they approach the same negative constant in the far future. Consequently, we show that such an interacting holographic energy model cannot accommodate a transition from the dark energy with $\omega^{\rm eff}_{\rm \Lambda}\ge-1$ to the phantom regime with $\omega^{\rm eff}_{\rm \Lambda}<-1$.Comment: 11 pages, 2 eps figures, final version to appear in PL

Generalized Brans-Dicke cosmology in the presence of matter and dark energy

We study the Generalized Brans-Dicke cosmology in the presence of matter and dark energy. Of particular interest for a constant Brans-Dicke parameter, the de Sitter space has also been investigated.Comment: 9 page

Kinetic k-essence ghost dark energy model

A ghost dark energy model has been recently put forward to explain the current accelerated expansion of the Universe. In this model, the energy density of ghost dark energy, which comes from the Veneziano ghost of QCD, is proportional to the Hubble parameter, $\rho_D=\alpha H$. Here $\alpha$ is a constant of order $\Lambda^3_{QCD}$ where $\Lambda_{QCD}\sim 100 MeV$ is the QCD mass scale. We consider a connection between ghost dark energy with/without interaction between the components of the dark sector and the kinetic k-essence field. It is shown that the cosmological evolution of the ghost dark energy dominated Universe can be completely described a kinetic k-essence scalar field. We reconstruct the kinetic k-essence function $F(X)$ in a flat Friedmann-Robertson-Walker Universe according to the evolution of ghost dark energy density.Comment: 11 pages, 15 figures, some clarifications added in the introduction, added references. Accepted for publication in Phys. Lett.

Interacting cosmic fluids in power-law Friedmann-Robertson-Walker cosmological models

We provide a detailed description for power--law scaling Friedmann-Robertson-Walker cosmological scenarios dominated by two interacting perfect fluid components during the expansion. As a consequence of the mutual interaction between the two fluids, neither component is conserved separately and the energy densities are proportional to $1/t^{2}$. It is shown that in flat FRW cosmological models there can exist interacting superpositions of two perfect fluids (each of them having a positive energy density) which accelerate the expansion of the universe. In this family there also exist flat power law cosmological scenarios where one of the fluids may have a ``cosmological constant" or "vacuum energy" equation of state ($p =-\rho$) interacting with the other component; this scenario exactly mimics the behavior of the standard flat Friedmann solution for a single fluid with a barotropic equation of state. These possibilities of combining interacting perfect fluids do not exist for the non-interacting mixtures of two perfect cosmic fluids, where the general solution for the scale factor is not described by power--law expressions and has a more complicated behavior. In this study is considered also the associated single fluid model interpretation for the interaction between two fluids.Comment: 10 pages. Accepted for publication in Physics Letters

Non-flat universe and interacting dark energy model

For non-flat universe of $k\not=0$, we investigate a model of the interacting holographic dark energy with cold dark matter (CDM). There exists a mixture of two components arisen from decaying of the holographic dark energy into CDM. In this case we use the effective equations of state ($\omega^{\rm eff}_{\rm \Lambda}, \omega^{\rm eff}_{\rm m}$) instead of the native equations of state ($\omega_{\rm \Lambda},\omega_{\rm m})$. Consequently, we show that interacting holographic energy models in non-flat universe cannot accommodate a transition from the dark energy to the phantom regime.Comment: 12 pages, 4 figures, version to appear in PL

Interacting holographic dark energy model and generalized second law of thermodynamics in non-flat universe

In the present paper we consider the interacting holographic model of dark energy to investigate the validity of the generalized second laws of thermodynamics in non-flat (closed) universe enclosed by the event horizon measured from the sphere of the horizon named $L$. We show that for $L$ as the system's IR cut-off the generalized second law is respected for the special range of the deceleration parameter.Comment: 11 pages, no figure