Enhancing Deep-UV Emission at 234 nm by Introducing Truncated Pyramid AlN/GaN Nanostructure with Fine-tuned Multiple Facets

The external quantum efficiency of a high-Al content (>0.6) AlGaN deep-ultraviolet (DUV) light-emitting diode is typically below 1% in the sub-250 nm wavelength range. One of the main reasons for...

Levantamiento y modelización tridimensional de la Torre del Negro o de Arráez, torre post-litoral del siglo XVI en El Algar (Región de Murcia, España)

Graphic survey and three-dimensional modelling of the Negro Tower or Arráez, post-coastal tower of the sixteenth century in El Algar (Region of Murcia, Spain)Post-coastal towers or rural fortress towers, built in the sixteenth century on the Mediterranean coast, had the mission of protecting the population and enhancing the repopulation of these areas, heavily punished by incursions by berber pirates. The Negro Tower or Arráez Tower, in El Algar-Cartagena (Region of Murcia, Spain), is one of those post-coastal lookout towers and was built in 1585. It is shaped like a truncated pyramid, square plan and a height of about 14,00 m. Originally, it had three floors and a terrace. Despite its degree of protection (it is a monument), its current state of conservation is semi-ruined. It has no cover, the vault of the first floor has collapsed and presents cracks that threaten its stability. Therefore, a research project has been developed that has included, among other aspects, the graphic survey with two complementary techniques: digital photogrammetry and 3D laser scanning. The result is an exhaustive graphic documentation that allows understanding the construction and allows the consolidation and volumetric recomposition of the tower. With this work, it is intended to contribute to the conservation and recovery of the heritage value of the Tower, as well as the integration of the historical monument in its natural and landscape environment.

Efficient Broadband Truncated-Pyramid-Based Metamaterial Absorber in the Visible and Near-Infrared Regions

We present a design of an ultra-broadband metamaterial absorber in the visible and near- infrared regions. The unit cell structure consists of a single layer of metallic truncated-pyramid resonator-dielectric-metal configuration, which results in a high absorption over a broad wavelength range. The absorber exhibits 98% absorption at normal incidence spanning a wideband range of 417–1091 nm, with >99% absorption within 822–1054 nm. The broadband absorption stability maintains 95% at large incident angles up to 40° for the transverse electric (TE)-mode and 20° for the transverse magnetic (TM)-mode. Furthermore, the polarization-insensitive broadband absorption is presented in this paper by analyzing absorption performance with various polarization angles. The proposed absorber can be applied for applications such as solar cells, infrared detection, and communication systems thanks to the convenient and compatible bandwidth for electronic THz sources.

No More Drop Panels in the Design for Punching Shear in Flat Plates

Punching shear failure at column-slab connection occurs in a brittle manner, which involves the formation of a truncated cone or a truncated pyramid. A set-up of swimmer bars system takes the shape of truncated steel pyramids to counteract the potential truncated pyramids of cracks. Each counteract truncated steel pyramid is formed by swimmer bars will generate four inclined planes intercepting approximately perpendicularly the four inclined planes of the failure truncated pyramid. A reference to a testing program of four square slabs with a concentric column will be used; these were constructed with overall dimensions of 2000 mm by 2000 mm, 150 mm thickness and 140 by 140 mm column in the middle. The results obtained from testing has proved that the efficiency of using swimmer bars system in slab-column connections has increased their punching shear capacity to more than 250% and has decreased their deflection by increasing the stiffness of the slab in the vicinity of the concentrated loads, moreover, the nature of the punching shear failure becomes ductile instead of brittle and obviates sudden failure. The need for drop panels to resist the punching shearing forces becomes unnecessary. The ultimate strength of punching shear is limited by the compression shear failure, which was never measured for the case of punching shear. The gain in ductility can reach levels matching those in flexural behavior.

DEVELOPMENT OF SOFTWARE TO DETERMINE PRESSURES IN MULTICELULARSILOS WITH CONCENTRIC AND ECCENTRIC DISCHARGE

A computer program for determining the pressures, horizontal and friction, in prismatic slender silos, with square section, eccentric hopper and mass flow, international codes taken as basis were: AS 3774 (1996), DIN 1055-6 (2005) and BS EN 1991-4 (2006) and the theories proposed by Safarian (1969) and Walker (1966). The development application was made possible by the development of a computational algorithm in programming “Borland Delphi”. The program was carried out for five silos projects with truncated pyramid form hopper considering the following eccentricities: 25%, 30%, 35% and 43%, as well as a concentric model for comparison. The computer program allowed SILOEXCENTRIC easily and quickly be applied to slender prismatic geometry of silos with concentric and eccentric hoppers. The results demonstrated the efficiency of the computer program for the proposed objectives So SILOEXCENTRIC results in pressures that are stored in files in “Notepad” format that may be accessed are generated. Besides files, various data are presented in graphical form, facilitating the assessment of horizontal pressures and friction, which proved adequate to international standards, considering the limit states.

A broadband ultraviolet light source using GaN quantum dots formed on hexagonal truncated pyramid structures

Broadband ultraviolet solid-state light emitter has been demonstrated based on the combined structure of MOCVD grown microstructure and the MBE grown quantum dots, thanks to the strain inhomogeneity of the multi-facet semiconductor microstructure.