Estudio experimental del Sistema de Albañilería Integral en la construcción de viviendas sismorresistentes. Experimental study of the Integral Masonry System in the construction of earthquake resistant houses

This paper presents the application of the Integral Masonry System (IMS) to the construction of earthquake resistant houses and its experimental study. To verify the security of this new type of building in seismic areas of the third world two prototypes have been tested, one with adobe and the other with hollow brick. In both cases it’s a two-story 6x6x6 m3 house built to scale 1/2. The tests are carried out at the Laboratory of Antiseismic Structures of the Department of Engineering, Pontifical Catholic University of Peru in Lima, in collaboration with the UPM (Technical University of Madrid). This article shows the design process of the prototypes to test, including the sizing of the reinforcements, the characteristics of the tests and the results obtained. These results show that the IMS with adobe or brick remains stable with no significant cracks faced with a severe earthquake, with an estimated acceleration of 1.8 g. Este artículo presenta una aplicación del Sistema de Albañilería Integral (SAI) a la construcción de viviendas sismorresistentes y su estudio experimental. Para verificar su seguridad para su construcción en zonas sísmicas del tercer mundo se han ensayado dos prototipos, uno con adobe, y otro con ladrillo hueco. Se trata de una vivienda de 6x6x6 m3 y dos plantas que se construyen a escala 1/2. Los ensayos se realizaron en el Laboratorio de Estructuras Antisísmicas del Departamento de Ingeniería de la Pontificia Católica Universidad del Perú (PUCP) de Lima en colaboración con la UPM (Universidad Politécnica de Madrid). Este artículo muestra el proceso de diseño de los prototipos a ensayar, incluido el dimensionado de los refuerzos, las características de los ensayos y los resultados obtenidos. Estos resultados muestran que el SAI con adobe o ladrillo permanece estable sin grietas significativas ante un sismo severo, con una aceleración estimada de 1,8 g

Sistema de autoconstrucción sismorresistente: características resistentes y proceso constructivo

The dwelling construction with soil, adobe or brick without call for technical advice is very typical in countries in process of development that are in areas of high seismic risk. To give an answer to the problem of earthquake building using these materials, providing simplicity of construction, we have worked for years in the use of the Integral Masonry System (IMS). The IMS is a system that, used combined with native materials, has earthquake resistant properties and its ease of implementation makes it suitable for self-build earthquake-resistant dwellings. This article describes the IMS, develops the constructive process applied to a type of two storey houses, and shows the seismic behaviour by means of the results obtained in the three test campaigns. The originality of the system lies in the use of a single type of prefabricated trusses, intertwined in the three spatial directions allowing create a dimensional mesh.<br><br>La autoconstrucción con tierra, adobe o ladrillo es muy habitual en los países en vías de desarrollo que están en zonas de alto riesgo sísmico. Ante la necesidad de dar respuesta al problema, aportando sencillez constructiva, hemos trabajado desde hace años en el empleo del Sistema de Albañilería Integral (SAI). El SAI es un sistema que, combinado con materiales autóctonos, aporta resistencia sísmica y su facilidad de ejecución lo hace adecuado para la autoconstrucción de viviendas antisísmicas. Este artículo describe el SAI, desarrolla el proceso constructivo aplicado a una vivienda tipo de dos alturas y muestra su comportamiento sismo-resistente mediante los resultados obtenidos en tres campañas de ensayos. La originalidad del sistema radica en el empleo de un solo tipo de armaduras prefabricadas en forma de cercha que se entrelazan entre si en las tres direcciones del espacio permitiendo crear una malla tridimensional

The amount of keratinized mucosa may not influence peri-implant health in compliant patients: A retrospective 5-year analysis

AIM (a) To investigate the influence of the keratinized mucosa (KM) on peri-implant health or disease and (b) to identify a threshold value for the width of KM for peri-implant health. MATERIALS AND METHODS The total dataset was subsampled, that is one implant was randomly chosen per patient. In 87 patients, data were extracted at baseline (prosthesis insertion) and 5 years including the width of mid-buccal KM, bleeding on probing, probing depth, plaque index and marginal bone level (MB). Spearman correlations with Holm adjustment for multiple testing were used for potential associations. RESULTS Depending on the definition of peri-implant diseases, the prevalence of peri-implantitis ranged from 9.2% (bleeding on probing threshold: <50% or ≥50%) to 24.1% (threshold: absence or the presence). The prevalence of peri-implant mucositis was similar, irrespective of the definition (54%-55.2%). The width of KM and parameters for peri-implant diseases demonstrated negligible (Spearman correlation coefficients: -0.2 < ρ < 0.2). No threshold value was detected for the width of mid-buccal KM in relation to peri-implant health. CONCLUSION The width of KM around dental implants correlated to a negligible extent with parameters for peri-implant diseases. No threshold value for the width of KM to maintain peri-implant health could be identified

Inhomogeneous vortex-state-driven enhancement of superconductivity in nanoengineered ferromagnet-superconductor heterostructures

Thin film heterostructures provide a powerful means to study the antagonism between superconductivity (SC) and ferromagnetism (FM). One interesting issue in FM-SC hybrids which defies the notion of antagonistic orders is the observation of magnetic field induced superconductivity (FIS). Here we show that in systems where the FM domains/islands produce spatial inhomogeneities of the SC order parameter, the FIS can derive significant contribution from different mobilities of the magnetic flux identified by two distinct critical states in the inhomogeneous superconductor. Our experiments on nanoengineered bilayers of ferromagnetic CoPt and superconducting NbN where CoPt/NbN islands are separated by a granular NbN, lend support to this alternative explanation of FIS in certain class of FM-SC hybrids.Comment: 5 figure

Pulsed Laser System to Simulate Effects of Cosmic Rays in Semiconductor Devices

Spaceflight system electronic devices must survive a wide range of radiation environments with various particle types including energetic protons, electrons, gamma rays, x-rays, and heavy ions. High-energy charged particles such as heavy ions can pass straight through a semiconductor material and interact with a charge-sensitive region, generating a significant amount of charge (electron-hole pairs) along their tracks. These excess charges can damage the device, and the response can range from temporary perturbations to permanent changes in the state or performance. These phenomena are called single event effects (SEE). Before application in flight systems, electronic parts need to be qualified and tested for performance and radiation sensitivity. Typically, their susceptibility to SEE is tested by exposure to an ion beam from a particle accelerator. At such facilities, the device under test (DUT) is irradiated with large beams so there is no fine resolution to investigate particular regions of sensitivity on the parts. While it is the most reliable approach for radiation qualification, these evaluations are time consuming and costly. There is always a need for new cost-efficient strategies to complement accelerator testing: pulsed lasers provide such a solution. Pulsed laser light can be utilized to simulate heavy ion effects with the advantage of being able to localize the sensitive region of an integrated circuit. Generally, a focused laser beam of approximately picosecond pulse duration is used to generate carrier density in the semiconductor device. During irradiation, the laser pulse is absorbed by the electronic medium with a wavelength selected accordingly by the user, and the laser energy can ionize and simulate SEE as would occur in space. With a tightly focused near infrared (NIR) laser beam, the beam waist of about a micrometer can be achieved, and additional scanning techniques are able to yield submicron resolution. This feature allows mapping of all of the sensitive regions of the studied device with fine resolution, unlike heavy ion experiments. The problematic regions can be precisely identified, and it provides a considerable amount of information about the circuit. In addition, the system allows flexibility for testing the device in different configurations in situ

Lifshitz transition and van Hove singularity in a Topological Dirac Semimetal

A topological Dirac semimetal is a novel state of quantum matter which has recently attracted much attention as an apparent 3D version of graphene. In this paper, we report critically important results on the electronic structure of the 3D Dirac semimetal Na3Bi at a surface that reveals its nontrivial groundstate. Our studies, for the first time, reveal that the two 3D Dirac cones go through a topological change in the constant energy contour as a function of the binding energy, featuring a Lifshitz point, which is missing in a strict 3D analog of graphene (in other words Na3Bi is not a true 3D analog of graphene). Our results identify the first example of a band saddle point singularity in 3D Dirac materials. This is in contrast to its 2D analogs such as graphene and the helical Dirac surface states of a topological insulator. The observation of multiple Dirac nodes in Na3Bi connecting via a Lifshitz point along its crystalline rotational axis away from the Kramers point serves as a decisive signature for the symmetry-protected nature of the Dirac semimetal's topological groundstate.Comment: 5 pages, 4 Figures, Related papers on topological Fermi arcs and Weyl Semimetals (WSMs) are at http://physics.princeton.edu/zahidhasangroup/index.htm