Estudio experimental del comportamiento a compresión de hormigones autocompactantes reforzados con fibras de acero = Experimental study of performance self-compacting concrete reinforced with steel fibers

Self-compacting steel fibers reinforced concrete simultaneously has the advantages of self-compacting concrete and reinforced with fibers. A material of high performance in their laying on site, toughness and ductility is achieved. This paper has studied the mechanical behavior of a self-compacting concrete reinforced with steel fibers. Have been made compression tests, as well as non-destructive testing (measuring the speed of ultrasound and sclerometer test). The results show the variation of the response of concrete with time, the difference with the traditional concrete and the feasibility of using non-destructive techniques for controlling this type of concrete

Evolución del coeficiente de Poisson de un hormigón autocompactante reforzado con fibras de acero

En este trabajo se estudia la variación de la edad y el nivel de carga del coeficiente de Poisson de un hormigón autocompactante reforzado con fibras de acero (HACRFA) fabricado por la empresa Lafarge-Holcin

Evolución del módulo de elasticidad de un hormigón autocompactante reforzado con fibras de acero

En este trabajo se han ensayado a compresión hasta rotura probetas de un HACRFA fabricado por Lafarge-Holci

Caracterización mecánica de hormigones autocompactantes reforzados con fibras de acero

El hormigón autocompactante reforzado con fibras de acero presenta simultáneamente las ventajas de los hormigones autocompactantes y de los reforzados con fibras. Se consigue un material de altas prestaciones con mayor tenacidad y ductilidad. En este trabajo se ha estudiado el comportamiento mecánico de un hormigón autocompactante reforzado con fibras de acero. Se han realizado ensayos a compresión, tracción y flexión a distintas edades; así como ensayos no destructivos (medida de la velocidad de ultrasonidos e índice esclerométrico). Los resultados muestran la variación de la respuesta del hormigón con el tiempo y la diferencia existente con hormigones tradicionales

Premolares supernumerarios. A propósito de un caso clínico

En este artículo presentamos un caso clínico de un paciente varón de 19 años de edad que acudió a las consultas externas del Servicio de Cirugía Oral y Maxilofacial de los Hospitales Universitarios Virgen del Rocío de Sevilla debido al hallazgo radiológico casual de un premolar incluido por parte de su odontólogo

Engineering aspheric liquid crystal lenses by using the transmission electrode technique

The transmission electrode technique has been recently proposed as a versatile method to obtain various types of liquid-crystal (LC) lenses. In this work, an equivalent electric circuit and new analytical expressions based on this technique are developed. In addition, novel electrode shapes are proposed in order to generate different phase profiles. The analytical expressions depend on manufacturing parameters that have been optimized by using the least squares method. Thanks to the proposed design equations and the associated optimization, the feasibility of engineering any kind of aspheric LC lenses is demonstrated, which is key to obtain aberration-free lenses. The results are compared to numerical simulations validating the proposed equations. This novel technique, in combination with the proposed design equations, opens a new path for the design and fabrication of LC lenses and even other types of adaptive-focus lenses based on voltage control.This work was supported by Comunidad de Madrid and FEDER Program (S2018/NMT-4326), the Ministerio de Economía y Competitividad of Spain (TEC2016-77242-C3-1-R and TEC2016-76021-C2-2-R), the FEDER/Ministerio de Ciencia, Innovación y Universidades and Agencia Estatal de Investigación (RTC2017-6321-1, PID2019-107270RB-C21 and PID2019-109072RB-C31)

Design of beams and slabs of self-compacting concrete fittings working to flexion

Numerous experimental studies indicate that addition of fibers substantially increases the shear strength of concrete and mortar beams, and that stirrups and reinforcing fibers combination can be really effective. When steel fibers are used as a supplement or substitute for vertical stirrups or folded bars, we obtain the following characteristics: The fibers are distributed randomly by the volume of the concrete with a closer separation than can be achieved with the Armor; The tensile strength at first crack, the ultimate tensile strength and the shear friction resistance are increased

Double electromagnetically induced transparency resonance in slotted metasurfaces supporting bound states in the continuum

This work proposes and theoretically demonstrates a double electromagnetic induced transparency resonance generated by a novel dielectric metasurface consisting of a periodic array of square slots. The resonances stem from symmetry-protected bound states in the continuum whose quality factor tends to infinity when the structure is symmetric. The quasi-bound states in the continuum supported by the asymmetric metasurface can be exploited to obtain double high quality factor resonances in transmission (electromagnetic induced transparency like effect) that can be modulated with the external refractive index for sensing.This work was supported by Comunidad de Madrid and FEDER Program (S2018/NMT-4326), the Ministerio de Economía y Competitividad of Spain (TEC2016-77242-C3-1-R and TEC2016-76021-C2-2-R), the FEDER/Ministerio de Ciencia, Innovación y Universidades and Agencia Estatal de Investigación (RTC2017-6321-1, PID2019-107270RB-C21 and PID2019-109072RB-C31)

Strongly resonant silicon slot metasurfaces with symmetry-protected bound states in the continuum

In this work, a novel all-dielectric metasurface made of arrayed circular slots etched in a silicon layer is proposed and theoretically investigated. The structure is designed to support both Mie-type multipolar resonances and symmetry-protected bound states in the continuum (BIC). Specifically, the metasurface consists of interrupted circular slots, following the paradigm of complementary split-ring resonators. This configuration allows both silicon-on-glass and free-standing metasurfaces and the arc length of the split-rings provides an extra tuning parameter. The nature of both BIC and non-BIC resonances supported by the metasurface is investigated by employing the Cartesian multipole decomposition technique. Thanks to the non-radiating nature of the quasi-BIC resonance, extremely high Q-factor responses are calculated, both by fitting the simulated transmittance spectra to an extended Fano model and by an eigenfrequency analysis. Furthermore, the effect of optical losses in silicon on quenching the achievable Q-factor values is discussed. The metasurface features a simple bulk geometry and sub-wavelength dimensions. This novel device, its high Q-factors, and strong energy confinement open new avenues of research on light-matter interactions in view of new applications in non-linear devices, biological sensors, and optical communications.Ministerio de Ciencia, Innovación y Universidades (PID2019-107270RB-C21, PID2019-109072RB-C31, RTC2017-6321-1); Comunidad de Madrid (S2018/NMT-4326); Ministerio de Economía y Competitividad (TEC2016-76021-C2-2-R, TEC2016-77242-C3-1-R)

Test Bench for Highly Segmented GRIT Double-Sided Silicon Strip Detectors: A Detector Quality Control Protocol

This work deals with the characteristics of highly segmented double-sided silicon detectors. These are fundamental parts in many new state-of-the-art particle detection systems, and therefore they must perform optimally. We propose a test bench that can handle 256 electronic channels with off-the-shelf equipment, as well as a detector quality control protocol to ensure that the detectors meet the requirements. Detectors with a large number of strips bring new technological challenges and issues that need to be carefully monitored and understood. One of the standard 500 μ m thick detectors of the GRIT array was investigated, undergoing studies that revealed its IV curve, charge collection efficiency, and energy resolution. From the data obtained, we calculated, among other things, the depletion voltage (110 V), the resistivity of the bulk material (9 kΩ·cm), and the electronic noise contribution (8 keV). We present, for the first time, a methodology called “the energy triangle’’ to visualize the effect of charge sharing between two adjacent strips and to study the hit distribution with the interstrip-to-strip hit ratio (ISR).This research was partially supported by the MICINN of Spain, Grant No. EQC2018-004395-P, and European Regional Development Fund (FEDER) 2014-2020 and “Consejería deTransformación Económica, Industria, Conocimiento y Universidades de Junta de Andalucía”, under Project No. IE17_5380_UHU