Assessment of the splitting-tensile strength of ZP-306 steel fiber reinforced concrete

El concreto reforzado con fibras de acero (CRFA) es un material con gran potencial de uso en viviendas de concreto de baja altura, ya que la capacidad de resistencia de los muros está controlada por la resistencia a tensión diagonal. El artículo presenta los resultados de un estudio experimental para caracterizar la resistencia a tensión por compresión diametral del CRFA que es elaborado con fibra ZP-306 y con concretos locales. El programa experimental incluyó el ensayo de 52 especímenes en forma de cilindros. En el estudio se discuten los modelos de predicción disponibles y se realiza un análisis estadístico para comparar los resultados calculados con los datos medidos. Con base en las tendencias de los resultados experimentales, se proponen ecuaciones para estimar los parámetros que describen la envolvente del comportamiento esfuerzo-deformación del CRFA sometido a esfuerzos de compresión diametral. Las ecuaciones se han desarrollado en un formato versátil para ser incluidas en un reglamento de diseño. Abstract Steel fibers reinforced concrete (SFRC) is a material with great potential to be used in low-rise concrete housing because the strength capacity of the walls is controlled by diagonal tension strength. The paper shows the results of an experimental study intended to characterize splitting-tensile strength of SFRC made of both ZP-306 fiber and local concrete. The experimental program included the tests of 52 cylindrical-shaped specimens. The study discusses the available predictive models and shows a statistical analysis to compare the predicted results with measured data. Based on trends of the experimental results, equations to estimate the parameters describing the backbone of the stress-strain behavior of SFRC under splitting-tensile strength are proposed. The equations have been developed in a versatile format to be included in a design code

On the characteristics of natural hydraulic dampers: An image-based approach to study the fluid flow behaviour inside the human meniscal tissue

The meniscal tissue is a layered material with varying properties influenced by collagen content and arrangement. Understanding the relationship between structure and properties is crucial for disease management, treatment development, and biomaterial design. The internal layer of the meniscus is softer and more deformable than the outer layers, thanks to interconnected collagen channels that guide fluid flow. To investigate these relationships, we propose a novel approach that combines Computational Fluid Dynamics (CFD) with Image Analysis (CFD-IA). We analyze fluid flow in the internal architecture of the human meniscus across a range of inlet velocities (0.1mm/s to 1.6m/s) using high-resolution 3D micro-computed tomography scans. Statistical correlations are observed between architectural parameters (tortuosity, connectivity, porosity, pore size) and fluid flow parameters (Re number distribution, permeability). Some channels exhibit Re values of 1400 at an inlet velocity of 1.6m/s, and a transition from Darcy's regime to a non-Darcian regime occurs around an inlet velocity of 0.02m/s. Location-dependent permeability ranges from 20-32 Darcy. Regression modelling reveals a strong correlation between fluid velocity and tortuosity at high inlet velocities, as well as with channel diameter at low inlet velocities. At higher inlet velocities, flow paths deviate more from the preferential direction, resulting in a decrease in the concentration parameter by an average of 0.4. This research provides valuable insights into the fluid flow behaviour within the meniscus and its structural influences.Comment: 20 Pages, 5 Figure

World Fairs. Special Issue of Anthropological Journal of European Cultures

info:eu-repo/semantics/publishedVersio

Abrupt Convergence and Escape Behavior for Birth and Death Chains

We link two phenomena concerning the asymptotical behavior of stochastic processes: (i) abrupt convergence or cut-off phenomenon, and (ii) the escape behavior usually associated to exit from metastability. The former is characterized by convergence at asymptotically deterministic times, while the convergence times for the latter are exponentially distributed. We compare and study both phenomena for discrete-time birth-and-death chains on Z with drift towards zero. In particular, this includes energy-driven evolutions with energy functions in the form of a single well. Under suitable drift hypotheses, we show that there is both an abrupt convergence towards zero and escape behavior in the other direction. Furthermore, as the evolutions are reversible, the law of the final escape trajectory coincides with the time reverse of the law of cut-off paths. Thus, for evolutions defined by one-dimensional energy wells with sufficiently steep walls, cut-off and escape behavior are related by time inversion.Comment: 2 figure

The chimpanzee GH locus: composition, organization, and evolution

In most mammals the growth hormone (GH) locus comprises a single gene expressed primarily in the anterior pituitary gland. However, in higher primates multiple duplications of the GH gene gave rise to a complex locus containing several genes. In man this locus comprises 5 genes including GH-N (expressed in pituitary) and four genes expressed in the placenta, but in other species the number and organization of these genes varies. The situation in chimpanzee has been unclear, with suggestions of up to seven GH-like genes. We have re-examined the GH locus in chimpanzee and have deduced the complete sequence. The locus includes five genes apparently organized in a similar fashion to those in human, with two of these genes encoding GH-like proteins, and three encoding chorionic somatomammotropins/placental lactogens (CSHs/PLs). There are notable differences between the human and chimpanzee loci with regard to the expressed proteins, gene regulation and gene conversion events. In particular, one human gene (hCSH-L) has changed substantially since the chimpanzee/human split, potentially becoming a pseudogene, while the corresponding chimpanzee gene (CSH-A1) has been conserved, giving a product almost identical to the adjacent CSH-A2. Chimpanzee appears to produce two CSHs, with potentially differing biological properties, whereas human produces a single CSH. The pattern of gene conversion in human has been quite different from that in chimpanzee. The region around the GH-N gene in chimpanzee is remarkable polymorphic, unlike the corresponding region in human. The results shed new light on the complex evolution of the GH-locus in higher primates

Overview of progress in European medium sized tokamaks towards an integrated plasma-edge/wall solution

Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n = 2 RMP maintaining good confinement HH(98,y2) 0.95. Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes.European Commission (EUROfusion 633053

First-principles calculation of the thermal properties of silver

The thermal properties of silver are calculated within the quasi-harmonic approximation, by using phonon dispersions from density-functional perturbation theory, and the pseudopotential plane-wave method. The resulting free energy provides predictions for the temperature dependence of various quantities such as the equilibrium lattice parameter, the bulk modulus, and the heat capacity. Our results for the thermal properties are in good agreement with available experimental data in a wide range of temperatures. As a by-product, we calculate phonon frequency and Grueneisen parameter dispersion curves which are also in good agreement with experiment.Comment: 9 pages, 8 figures, submitted to Phys. Rev. B April 30, 1998). Other related publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm