Effects of texturization due to chemical etching and laser on the optical properties of multicrystalline silicon for applications in solar cells

In this work we carried out the texturization of surfaces of multicrystalline silicon type-p in order to decrease the reflection of light on the surface, using the chemical etching method and then a treatment with laser. In the first method, it was immersed in solutions of HF:HNO3:H2O, HF:HNO3:CH3COOH, HF:HNO3:H3PO4, in the proportion 14:01:05, during 30 seconds, 1, 2 and 3 minutes. Subsequently with a laser (ND:YAG) grids were generated beginning with parallel lines separated 50μm. The samples were analyzed by means of diffuse spectroscopy (UV-VIS) and scanning electron micrograph (SEM) before and after the laser treatment. The lowest result of reflectance obtained by HF:HNO3:H2O during 30 seconds, was of 15.5%. However, after applying the treatment with laser the reflectance increased to 17.27%. On the other hand, the samples treated (30 seconds) with acetic acid and phosphoric acid as diluents gives as a result a decrease in the reflectance values after applying the laser treatment from 21.97% to 17.79% and from 27.73% to 20.03% respectively. The above indicates that in some cases it is possible to decrease the reflectance using jointly the method of chemical etching and then a laser treatment

Producción audiovisual universitaria: espacios de innovación docente en Iberoamérica

The inclusion of new media in the field of education is appearing more and more frequently. University teaching is increasingly utilizing these audiovisual, digital and multimedia resources to provide a better learning experience. For the production of these materials, designated spaces have been created, however, there is a lack of consensus regarding the name attributed to them. In this study, we carried out a bibliographical review of the production of educational audiovisual content and the spaces devoted to this end in order to contextualise it prior to the in-depth interviews. With the aim of getting to know and delve deeper into the audiovisual proposals that are taking place in the Ibero-American sphere, we interviewed the people responsible for these innovative spaces in three universities. We concluded that the three institutions dedicated human resources, equipment and specialised spaces for video development; pedagogical support is necessary to outline the educational intention of the materials to be created; and it is necessary to empower both teachers and students in the development and curation of materials. The results may be useful for other universities and centres interested in venturing into video production, as well as for collaboration opportunities to enrich the learning experience and teacher training.La incorporación de los nuevos medios en el ámbito educativo aparece cada vez con más frecuencia. La docencia universitaria se vale cada vez más de estos materiales audiovisuales, digitales y multimedia para proporcionar una mejor experiencia en el aula. Para la producción de estos materiales se han creado espacios destinados a su desarrollo, no obstante, existe falta de consenso en el nombre atribuido a los mismos. En este estudio se ha realizado, en primer lugar, una revisión bibliográfica relativa a la producción de contenidos audiovisuales educativos y a los espacios en los que estos se desarrollan para contextualizar de manera previa a las entrevistas en profundidad. Con el objetivo de conocer y ahondar en las propuestas audiovisuales que se están dando en el ámbito iberoamericano, se ha entrevistado a personas responsables de estos espacios de innovación en tres universidades. Con lo que se ha podido concluir que las tres instituciones dedican recursos humanos, equipamiento y espacio especializado para el desarrollo de vídeo. El acompañamiento pedagógico es necesario para delinear la intención educativa de los materiales a desarrollar y es necesario empoderar tanto a docentes como alumnos en el desarrollo y curaduría de materiales. Los resultados pueden ser de utilidad para otras universidades y centros interesados en incursionar en la producción de vídeo, así como para oportunidades de colaboración que coadyuven a enriquecer la experiencia de aprendizaje y la formación docente

Prevalencia de maloclusiones en niños de una escuela en Cartagena de Indias

La maloclusión es una afección del desarrollo, es la patología donde los controles anatomo-fisiológicos del sistema estomatognático se encuentran en desarmonía con los arcos dentarios. Las maloclusiones están presentes desde el origen del individuo, o bien se instalan durante las primeras etapas de vida. Las maloclusiones puede estar asociada con problemas de tipo esquelético, dental o hábitos parafuncionales como: deglución atípica, succión digital y respiración bucal; siendo estos los factores más importantes para su evolución

Implementation Of MOPROSOFT level i and ii in software development companies in the Colombian Caribbean, a commitment to the software product quality region

Currently, over 90 % of the world market universe of software development is constituted by SMEs. These organizations usually sees the implementation of methodologies are 'too heavy' to be adopted in their daily actions. Thus a model that is adapted to the needs of SME developers of software should primarily focus on: Continuous Improvement both processes Software development, like other fundamental aspects of the organization as such supporters as the quality process that results in high quality products, competitive in the national and international markets. In accordance with the above stated, this research paper in the first instance, contextualizes about different quality models in the area of software development, then the model features MoProSoft delimited, then the process of implementing the methodology defined in organizations, poses the same improvements in this way for more efficient results and conclusions of the research project

On Reducing the Energy Consumption of Software: From Hurdles to Requirements

International audienceBackground. As software took control over hardware in many domains, the question of the energy footprint induced by the software is becoming critical for our society, as the resources powering the underlying infrastructure are finite. Yet, beyond this growing interest, energy consumption remains a difficult concept to master for a developer.Aims. The purpose of this study is to better understand the root causes that prevent software energy consumption to be more widely adopted by developers and companies.Method. To investigate this issue, this paper reports on a qualitative study we conducted in an industrial context. We applied an in-depth analysis of the interviews of 10 experienced developers and summarized a set of implications.Results. We argue that our study delivers i) insightful feedback on how green software design is considered among the interviewed developers and ii) a set of findings to build helpful tools, motivate further research, and establish better development strategies to promote green software design.Conclusion. This paper covers an industrial case study of developers' awareness of green software design and how to promote it within the company. While it might not be generalizable for any company, we believe our results deliver a common body of knowledge with implications to be considered for similar cases and further researches

APPLICATION OF THE RECURRENT DATA ANALYSIS ON FL245 SWITCHES AT INTERCONEXIÓN ELÉCTRICA S.A. APLICACIÓN DEL ANÁLISIS DE DATOS RECURRENTES SOBRE INTERRUPTORES FL245 EN INTERCONEXIÓN ELÉCTRICA S.A.

Recurrent data arise when a unit (or group of such units) is monitored over time and a particular event (or group of events) occurs at several points of the observation period, for example, times of recurrent episodes of a disease in patients or times of repair of a manufactured product. Many systems, subsystems, and components (which we generically refer to as “units”) have more than one cause of failure. In some applications and for some purposes it is important to distinguish between the different failure causes (sometimes referred to as “failure modes”). For purposes of improving reliability, it is essential to identify the cause of failure up to the component level and, in many applications, up to the actual physical cause of failure. This paper presents an application of the recurrent data analysis performed on type FL245 switches (repairable units of Interconexión Eléctrica S.A., ISA), that includes the use of non-parametric and parametric statistical methods, considering several failure modes.Los datos recurrentes surgen cuando una unidad (o un grupo de tales unidades) es monitoreada a través del tiempo y un evento particular (o grupo de eventos) ocurre en varios puntos del periodo de observación, por ejemplo, los tiempos de episodios recurrentes de una enfermedad en pacientes o los tiempos de reparación de un producto manufacturado. Muchos sistemas, subsistemas y componentes (que genéricamente son denominadas “unidades”) tienen asociadas más de una causa o modo de falla. En algunas aplicaciones, y para ciertos propósitos, es importante distinguir entre las causas o modos de falla. Para mejorar la confiabilidad, es esencial identificar la causa de falla hasta el nivel de componente, y en muchas aplicaciones, hasta la causa física real de una falla. En este trabajo, se presenta una aplicación del análisis de datos recurrentes realizado sobre interruptores tipo FL245 (unidades reparables en Interconexión Eléctrica S.A., ISA), que incluye el uso de métodos estadísticos no paramétricos y paramétricos considerando varios modos de falla

Aplicación del análisis de datos recurrentes sobre interruptores fl245 en interconexión eléctrica s.a.

Los datos recurrentes surgen cuando una unidad (o un grupo de tales unidades) es monitoreada a través del tiempo y un evento particular (o grupo de eventos) ocurre en varios puntos del periodo de observación, por ejemplo, los tiempos de episodios recurrentes de una enfermedad en pacientes o los tiempos de reparación de un producto manufacturado. Muchos sistemas, subsistemas y componentes (que genéricamente son denominadas “unidades”) tienen asociadas más de una causa o modo de falla. En algunas aplicaciones, y para ciertos propósitos, es importante distinguir entre las causas o modos de falla. Para mejorar la confiabilidad, es esencial identificar la causa de falla hasta el nivel de componente, y en muchas aplicaciones, hasta la causa física real de una falla. En este trabajo, se presenta una aplicación del análisis de datos recurrentes realizado sobre interruptores tipo FL245 (unidades reparables en Interconexión Eléctrica S.A., ISA), que incluye el uso de métodos estadísticos no paramétricos y paramétricos considerando varios modos de falla.Recurrent data arise when a unit (or group of such units) is monitored over time and a particular event (or group of events) occurs at several points of the observation period, for example, times of recurrent episodes of a disease in patients or times of repair of a manufactured product. Many systems, subsystems, and components (which we generically refer to as “units”) have more than one cause of failure. In some applications and for some purposes it is important to distinguish between the different failure causes (sometimes referred to as “failure modes”). For purposes of improving reliability, it is essential to identify the cause of failure up to the component level and, in many applications, up to the actual physical cause of failure. This paper presents an application of the recurrent data analysis performed on type FL245 switches (repairable units of Interconexión Eléctrica S.A., ISA), that includes the use of non-parametric and parametric statistical methods, considering several failure modes

Development of interference filters for porous silicon based photoluminescent devices

[ES] Las propiedades fotoluminiscentes y electroluminiscentes en el visible del silicio poroso hacen de éste un material muy interesante para el desarrollo de disposotivos optoelectrónicos. Para la obtención de dispositivos de calidad es necesario reducir la semianchura del espectro de luminiscencia del silicio poroso, típicamente de unos 100 nm, para conseguir una emisión monocromática. Esto puede conseguirse formando sobre la capa luminiscente una estructura multicapa, también de silicio poroso, que actúe a modo de filtro interferencial. Así se consigue estrechar el rango de emisión cuanto se desee, sencillamente diseñando el filtro de manera conveniente. En este artículo se estudian las propiedades ópticas de las capas de silicio poroso para el posterior diseño de estos filtros.[EN] Porous silicon’s photoluminescent and electroluminescent properties make it a very interesting material for the development of optoelectronic devices. To obtain high quality devices it is mandatory to narrowen the porous silicon luminescent spectrum, tipically about 100 nm wide. This can be obtained by forming a porous silicon multilayer structure on the luminescent layer that acts as an interference filter. Thus, the emission spectrum can be narrowed as much as wished by simply designing the filter in the appropriate way. In this article, the optical properties of porous silicon layers are studied for future filter design.Este trabajo ha sido financiado por el Ministerio de Ciencia y Tecnología a través de la Comisión Interministerial de Ciencia y Tecnología, mediante el Proyecto de Investigación MAT2000-0375- C02-01.Peer reviewe

Depth-resolved microspectroscopy of porous silicon multilayers

3 pages, 3 figures.We have measured depth-resolved microphotoluminescence (PL) and micro-Raman spectra on the cross section of porous silicon multilayers to sample different layer depths. The PL emission band gets stronger, blueshifts, and narrows at the high porosity layers. On the contrary, the Raman band weakens and broadens. This band is fitted to the phonon confinement model. With the bulk silicon phonon frequency and its linewidth as free parameters, we obtain crystallite size, temperature, and stress as a function of depth. Sizes are larger than those estimated from PL. Laser power was reduced to eliminate heating effects. Compressive stresses in excess of 10 kbar are found in the deepest layer due to the lattice mismatch with the substrate.The authors acknowledge financial support from the Spanish CICyT (Project Nos. MAT96-0395-CP and MAT97- 0725).Peer reviewe