Embedment of metal nanoparticles in GaAs and Si for plasmonic absorption enhancement in intermediate band solar cells

The high near-field enhancement occurring in the vicinity of metallic nanoparticles (MNPs) sustaining surface plasmons can only be fully exploited in photovoltaic devices if the MNPs are placed inside their semiconducting material, in the photoactive region. In this work an experimental procedure is studied to embed MNPs in gallium arsenide (GaAs) and silicon (Si), which can be applied to other semiconductor host materials. The approach consists in spin-coating colloidal MNPs dispersed in solution onto the substrate surface. Then a capping layer of the same material as the substrate is deposited on top to embed the MNPs in the semiconductor. The extinction spectra of silver (Ag) and gold (Au) MNPs embedded in GaAs and Si is modeled with Mie theory for comparison with optical measurements. This contribution constitutes the initial step towards the realization of quantum-dot intermediate band solar cells (QD-IBSC) with MN

Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes

This paper presents a numerical study of the light focusing properties of dielectric spheroids with sizes comparable to the illuminating wavelength. An analytical separation-of-variables method is used to determine the electric field distribution inside and in the near-field outside the particles. An optimization algorithm was implemented in the method to determine the particles’ physical parameters that maximize the forward scattered light in the near-field region. It is found that such scatterers can exhibit pronounced electric intensity enhancement (above 100 times the incident intensity) in their close vicinity, or along wide focal regions extending to 10 times the wavelength. The results reveal the potential of wavelength-sized spheroids to manipulate light beyond the limitations of macroscopic geometrical optics. This can be of interest for several applications, such as light management in photovoltaic

Indicator-based MONEDA: A Comparative Study of Scalability with Respect to Decision Space Dimensions

Proceedings of: 2011 IEEE Congress on Evolutionary Computation (CEC), New Orleans, LA, June 5-8 2011The multi-objective neural EDA (MONEDA) was proposed with the aim of overcoming some difficulties of current MOEDAs. MONEDA has been shown to yield relevant results when confronted with complex problems. Furthermore, its performance has been shown to adequately adapt to problems with many objectives. Nevertheless, one key issue remains to be studied: MONEDA scalability with regard to the number of decision variables. In this paper has a two-fold purpose. On one hand we propose a modification of MONEDA that incorporates an indicator-based selection mechanism based on the HypE algorithm, while, on the other, we assess the indicator-based MONEDA when solving some complex two-objective problems, in particular problems UF1 to UF7 of the CEC 2009 MOP competition, configured with a progressively-increasing number of decision variables.This work was supported by projects CICYT TIN2008-06742-C02-02/TSI, CICYT TEC2008-06732-C02-02/TEC, SINPROB, CAM CONTEXTS S2009/TIC-1485 and DPS2008-07029-C02-02.Publicad

Moving away from error-based learning in multi-objective estimation of distribution algorithms

Proceedings of: 12th annual conference on Genetic and evolutionary computation (GECCO '10). Portland, Oregon, USA, July 7-11, 2010.In this work we analyze the model-building issue and the requirements it imposes on the learning paradigm being used. We argue that error-based learning, the class of learning most commonly used in MOEDAs, is responsible for current MOEDA underachievement. We present ART as a viable alternative and present a novel algorithm called multi-objective ART-based EDA (MARTEDA) that uses a Gaussian ART neural network for model-building and an hypervolume based selector as described for the HypE algorithm. We experimentally show that thanks to MARTEDA's novel model-building approach and an indicator-based population ranking the algorithm it is able to outperform similar MOEDAs and MOEAs.This work was supported in part by projects CICYT TIN2008-06742-C02-02/TSI, CICYT TEC2008-06732-C02-02/TEC, DPS2008-07029-C02-02 and CAM CONTEXTS S2009/TIC-1485.Publicad

Upper limits to absorption enhancement in thick solar cells using diffraction gratings

The application of diffraction gratings to solar cells is a promising approach to superseding the light trapping limits of conventional Lambertian structures. In this paper a mathematical formalism is derived for calculating the absorption that can be expected in a solar cell equipped with a diffraction grating, which can be applied to any lattice geometry and grating profile. Furthermore, the formalism is used to calculate the upper limit of total absorption that can theoretically be achieved using a diffraction grating. The derived formalism and limits are valid when the solar cell thickness is greater than the coherence length of the illuminating solar spectrum. Comparison is made to the upper limit achievable using an angularly selective Rugate filter, which is also calculated. Both limits are found to be considerably higher than the Lambertian limit within the range of sunlight concentration factors practically employed in photovoltaic systems (1–1000×). The upper limit of absorption using the diffraction grating is shown to be equal to the thermodynamic limit for all absorbances and concentration factors. The limit for the Rugate filter is generally lower, but tends to the thermodynamic limit for lower cell absorbance

A stopping criterion for multi-objective optimization evolutionary algorithms

This Paper Puts Forward A Comprehensive Study Of The Design Of Global Stopping Criteria For Multi-Objective Optimization. In This Study We Propose A Global Stopping Criterion, Which Is Terms As Mgbm After The Authors Surnames. Mgbm Combines A Novel Progress Indicator, Called Mutual Domination Rate (Mdr) Indicator, With A Simplified Kalman Filter, Which Is Used For Evidence-Gathering Purposes. The Mdr Indicator, Which Is Also Introduced, Is A Special-Purpose Progress Indicator Designed For The Purpose Of Stopping A Multi-Objective Optimization. As Part Of The Paper We Describe The Criterion From A Theoretical Perspective And Examine Its Performance On A Number Of Test Problems. We Also Compare This Method With Similar Approaches To The Issue. The Results Of These Experiments Suggest That Mgbm Is A Valid And Accurate Approach. (C) 2016 Elsevier Inc. All Rights Reserved.This work was funded in part by CNPq BJT Project 407851/2012-7 and CNPq PVE Project 314017/2013-

The Havana Capitol, geometry and proportion through its original plans

[EN] The research on the National Capitol Building in Havana, Cuba, aims to study the building and its constructive solutions and materials, by means of the extensive graphic and photographic documentation preserved in the archives of the city. This documentation is a rigorous source of technical information, useful for analyzing the building in detail and understanding and dating its different construction phases. The research was developed in the city of Havana, Cuba, in the last five years in coordination with the Office of the City Historian, and it allowed creating a significant collection of plans, images and other graphic documents as a basis for future research. This article focuses on analyzing the work from its original plans (geometry and proportion, techniques of representation and graphic quality), which are a work of art by themselves, a meticulous handwork done by several Cuban architects and engineers. These documents have never seen the light until now.[ES] El objetivo de la investigación realizada en el Capitolio de La Habana se centra en estudiar el edificio, sus soluciones constructivas y materiales, en base a la extensa documentación gráfica y fotográfica existente en los diferentes archivos de la ciudad. Esta documentación constituye una fuente rigurosa de información técnica, útil para analizar en detalle el edificio y comprender y datar sus diferentes fases constructivas. La investigación ha sido desarrollada en La Habana, Cuba, durante los últimos cinco años en coordinación con la Oficina del Historiador de la Ciudad y ha permitido crear un archivo de planos, imágenes, y otros documentos gráficos como base de futuras investigaciones. Este artículo se centra en analizar la obra a partir de sus planos originales (geometría y proporción, técnicas de representación, calidad gráfica), que son una obra de arte en sí mismos y que nunca hasta ahora han visto la luz. Se trata de un minucioso trabajo realizado a mano por varios arquitectos e ingenieros cubanos.Mestre Martí, M.; Jiménez Delgado, A.; Ródenas López, M.; Jiménez Vicario, PM. (2018). El Capitolio de La Habana, geometría y proporción a través de sus planos originales. EGA. Revista de Expresión Gráfica Arquitectónica. 23(33):40-51. doi:10.4995/ega.2018.8859SWORD40512333DE LAS CUEVAS TORAYA, J. , (2001) . 500 years of construction in Cuba . Havana: Chavin. Servicios Gráficos y Editoriales, SLTHE ARCHITECT, (1933). No. 38. "The Capitol seen by an Architect ". The Architect, no. 38, p. 352FERNÁNDEZ, P. y Cía , (1933). The Book of the Capitol . Havana.SECRETARIAT OF PUBLIC WORKS (1931) . Inventory of non-consumable property of the Capitol. Havana: Ministry of Public Works.VEGA BOLAÑO, E., (2010). Diagnostic study of the cover of the National Capitol . Project of unpublished degree. Directors: MSc. Ing. Frank Díaz Alemán; Dr. Eng. OdalysÁlvarez Rodríguez. Havana: José Antonio Echevarría Polytechnic Higher Institute. School of Civil Engineering

Light absorption in the near field around surface plasmon polaritons

A semiclassical method is developed to calculate the energy absorption of an electronic system located in the near field of a metal nanoparticle sustaining surface plasmons. The results are found to be similar to those of photon absorption from ordinary transversal radiation. However, they are affected by a geometrical factor that can increase the absorption by several orders of magnitude. As example, we investigate ellipsoidal-shaped metal nanoparticles which, under favorable conditions, may provide near field aborption enhancements almost as large as 104, and in many cases above 10

Una revisión crítica del debate sobre las necesidades humanas desde el enfoque centrado en la persona

El artículo presenta algunos de los diferentes modelos teórico-explicativos sobre las necesidades humanas; revisa el estado del arte en las publicaciones recientes, y evalúa críticamente las limitaciones y potenciales que ellas tienen, desde una mirada sistémica y fenoménica desde un enfoque centrado en la persona.L’article présente certains des différents modèles théorico-explicatifs sur les besoins humains; il expose un état des lieux de la bibliographie récente, et évalue de manière critique les limites et potentiels que celles-ci peuvent représenter, dans une perspective systémique et propre au phénomène centrée sur la personne.The article presents some of the different theoretical-explanatory models on human needs; reviews the state-of-the-art in recent publications, and critically evaluates the limitations and potentials that they have, from a sistemic and phenomenical scope from person centered aproach