Insights on the large-scale deployment of a curated Web-of-Trust: the Debian project’s cryptographic keyring

The Debian project is one of the largest free software undertakings worldwide. It is geographically distributed, and participation in the project is done on a voluntary basis, without a single formal employee or directly funded person. As we will explain, due to the nature of the project, its authentication needs are very strict - User/password schemes are way surpassed, and centralized trust management schemes such as PKI are not compatible with its distributed and flat organization; fully decentralized schemes such as the OpenPGP Web of Trust are insufficient by themselves. The Debian project has solved this need by using what we termed a “curated Web of Trust”. We will explain some lessons learned from a massive key migration process that was triggered in 2014. We will present the social insight we have found from examining the relationships expressed as signatures in this curated Web of Trust, as well as a statistical study and forecast on aging, refreshment and survival of project participants stemming from an analysis on their key’s activity within the keyring

Effectiveness of the ASVAD valve in a reactor vessel bottom leak scenario

Decay heat removal can be seriously degraded by the presence of non-condensable gases in the cooling circuits. Nitrogen gas may be pushed into the primary system after a full discharge of the accumulators. This may produce various adverse effects: the interruption of natural circulation, the limitation of the primary to secondary heat transfer during the reflux cooling and prevent the startup of the active injection by stabilization of the pressure above the injection set point. State-of-the-art system codes have proven to be capable to simulate non-condensable gas effects in accident situations. The ASVAD valve, has been designed to avoid the inflow of nitrogen into the primary system by means of passive concepts. This paper addresses the complications derived from the nitrogen and evaluates the ASVAD valve performance through the simulation of a vessel bottom leak experiment at the LSTF facility in Japan.Peer ReviewedPostprint (published version

Ayudas hipermediales dinámicas para la solución de triángulos rectángulos, a estudiantes de décimo grado de la Institución Educativa Cristo Rey de Dosquebradas

Esta tesis contiene tablas de muestreo con análisis de datos y conclusiones a partir del objeto de estudio.La presente investigación toma lugar en el marco de la didáctica de la matemática, realizada en el contexto de la educación básica, con alumnas que cursan décimo grado de secundaria, con la intención de determinar los aportes didácticos que ofrecen las Ayudas Hipermediales Dinámicas en la solución de triángulos rectángulos, en lo referente al uso y creación de material educativo, adaptación de recursos educativos al contexto y estrategias comunicativas en el aula de clase. Una de las grandes problemáticas en grado décimo se relaciona con la complejidad de abordar la solución de triángulos en trigonometría donde se identifica, que la completitud en cuanto a una serie de conocimientos es requisito para la buena aplicación, comprensión y solución de los triángulos rectángulos. Esta propuesta basada en las ayudas hipermediales dinámicas (AHD) enfocada en la solución de triángulos rectángulos, dará cabida a la creación de secuencias didácticas que ayuden a la labor docente como estrategia formativa y de apoyo en la adquisición de nuevos contenidos educativos en la asignatura de trigonometría en grado décimo.The present investigation is carried out within the framework of the Mathematics Didactics, carried out in the context of basic education, with students who are in the tenth grade of secondary school, with the intention of determining the didactic contributions offered by the Dynamic Hypermedia Aids in the solution of right triangles, in relation to the use and creation of educational material, adaptation of educational resources to the context and communicative strategies in the classroom. One of the great problems in tenth degree is related to the complexity of approaching the solution of triangles in trigonometry where it is identified, that completeness in terms of a series of knowledge is a requisite for the good application, understanding and solution of right triangles. This proposal based on dynamic hypermedia aid (AHD) focused on the solution of right triangles, will allow for the creation of teaching sequences that help teaching as a training strategy and support in the acquisition of new educational content in the subject of trigonometry in tenth grade.MaestríaMagíster en Enseñanza de las MatemáticasContenido Introducción ………………………………………………………………………………….11 1. Descripción del problema ................................................................................................. 10 1.1. Problema educativo................................................................................................. 10 1.2. Formulación del problema ...................................................................................... 10 1.3. Objetivos de la investigación.................................................................................. 11 1.3.1. Objetivo General. ................................................................................................ 11 1.3.2. Objetivos Específicos.......................................................................................... 12 1.4. Justificación ............................................................................................................ 12 2. Marco teórico.................................................................................................................... 14 2.1. Antecedentes de la investigación............................................................................ 14 2.1.1. Investigaciones sobre el uso de AHD en la enseñanza ....................................... 14 2.1.2. Investigaciones relacionadas con el uso de las TIC en la solución de triángulos rectángulos. ........................................................................................................................... 15 2.2. Bases teóricas................................................................................................................ 15 2.2.1. Enfoque Pedagógico Socioconstructivista. ............................................................ 15 2.2.2. Características del socioconstructivismo ............................................................... 16 2.2.3. Las tareas del proceso educativo desde el Socioconstructivismo .......................... 18 2.2.4. Mediación............................................................................................................... 19 iv 2.2.5. Andamiaje .............................................................................................................. 19 2.2.6. Ayuda ajustada ....................................................................................................... 20 2.3. Zonas de desarrollo ....................................................................................................... 21 2.3.1. Zona de Desarrollo Próximo (ZDP)....................................................................... 22 2.3.2. Nivel Real de Desarrollo (NRD)............................................................................ 22 2.3.3. Nivel Potencial de Desarrollo (NPD)..................................................................... 22 2.3.4 Construcción de significados compartidos.............................................................. 24 2.3.5 Procesos de Internalización..................................................................................... 25 2.3.6 Actividad conjunta .................................................................................................. 27 2.4. Teorías de aprendizaje................................................................................................... 27 2.4.1. Aprendizaje Autónomo .......................................................................................... 27 2.4.2 Aprendizaje Colaborativo ....................................................................................... 32 2.4.3. Aprendizaje Basado en Problemas. (ABP) ............................................................ 37 2.4.4 Saberes Tecnológicos y Pedagógicos del Contenido (TPACK) ............................. 40 2.4.5 The Knowledge Quartet (KQ)................................................................................. 41 2.4.6 Conocimiento didáctico del contenido.................................................................... 42 2.4.7 Ambientes de aprendizaje ....................................................................................... 46 2.4.8 Modelo Van Hiele................................................................................................... 48 2.4.9 Fases de aprendizaje del modelo de Van Hiele....................................................... 51 v 2.5. Las TIC en la enseñanza de matemáticas...................................................................... 54 2.5.1 La AHD como Sistema Hipermedia Adaptativo (SHA)......................................... 55 2.6. Material educativo en la enseñanza de matemáticas..................................................... 56 2.6.1. Características del material educativo digital........................................................ 57 2.6.2. Usos de Material Educativo ................................................................................... 59 2.6.3. Adaptación de material educativo.......................................................................... 60 2.6.4. Estrategias comunicativas...................................................................................... 62 2.7. Solución de triángulos rectángulos ............................................................................... 63 3. Metodología de la investigación ....................................................................................... 64 3.1. Diseño cualitativo descriptivo................................................................................. 64 3.2. Contexto de la investigación................................................................................... 65 3.3. Técnicas e instrumentos de investigación............................................................... 65 3.3.1 Técnica de observación participante ....................................................................... 65 3.3.2 Registros video-gráficos...................................................................................... 66 3.4. Diseño del modelo pedagógico para la solución de triángulos rectángulos en el aula de clase 67 3.5 Procedimiento............................................................................................................. 69 3.5.1 Fases, objetivos y actividades del estudio........................................................... 69 3.6 Diseño y creación de la AHD..................................................................................... 71 vi 3.6.1 Diseño de la Secuencia Didáctica (SD)............................................................... 72 3.7 Diseño y organización del ambiente de aprendizaje .................................................. 72 3.7.1 Contexto Físico ....................................................................................................... 73 3.7.2 Rol del estudiante ................................................................................................ 73 3.7.3 Rol del docente.................................................................................................... 74 3.8 Categorías de análisis................................................................................................. 75 3.8.1 Creación y adaptación de materiales educativos................................................. 75 3.8.2 Aplicación y uso de los recursos educativos de la AHD..................................... 77 3.8.3 Estrategias comunicativas (con herramientas de trabajo colaborativo, autónomo y basado en problemas)............................................................................................................ 77 3.9 Evaluación de la AHD................................................................................................ 77 3.10 Secuencia didáctica................................................................................................. 78 4. Análisis e interpretación de resultados ............................................................................. 79 4.1 Creación de material educativo .................................................................................. 79 5. Conclusiones..................................................................................................................... 80 5.1 Conclusión general......................................................................................................... 82 6. Referencias bibliográficas................................................................................................. 8

Ayudas hipermediales dinámicas para la solución de triángulos rectángulos, a estudiantes de décimo grado de la Institución Educativa Cristo Rey de Dosquebradas.

Esta tesis contiene tablas de muestreo con análisis de datos y conclusiones a partir del objeto de estudio.La presente investigación toma lugar en el marco de la didáctica de la matemática, realizada en el contexto de la educación básica, con alumnas que cursan décimo grado de secundaria, con la intención de determinar los aportes didácticos que ofrecen las Ayudas Hipermediales Dinámicas en la solución de triángulos rectángulos, en lo referente al uso y creación de material educativo, adaptación de recursos educativos al contexto y estrategias comunicativas en el aula de clase. Una de las grandes problemáticas en grado décimo se relaciona con la complejidad de abordar la solución de triángulos en trigonometría donde se identifica, que la completitud en cuanto a una serie de conocimientos es requisito para la buena aplicación, comprensión y solución de los triángulos rectángulos. Esta propuesta basada en las ayudas hipermediales dinámicas (AHD) enfocada en la solución de triángulos rectángulos, dará cabida a la creación de secuencias didácticas que ayuden a la labor docente como estrategia formativa y de apoyo en la adquisición de nuevos contenidos educativos en la asignatura de trigonometría en grado décimo.The present investigation is carried out within the framework of the Mathematics Didactics, carried out in the context of basic education, with students who are in the tenth grade of secondary school, with the intention of determining the didactic contributions offered by the Dynamic Hypermedia Aids in the solution of right triangles, in relation to the use and creation of educational material, adaptation of educational resources to the context and communicative strategies in the classroom. One of the great problems in tenth degree is related to the complexity of approaching the solution of triangles in trigonometry where it is identified, that completeness in terms of a series of knowledge is a requisite for the good application, understanding and solution of right triangles. This proposal based on dynamic hypermedia aid (AHD) focused on the solution of right triangles, will allow for the creation of teaching sequences that help teaching as a training strategy and support in the acquisition of new educational content in the subject of trigonometry in tenth grade.MaestríaMagíster en Enseñanza de las MatemáticasContenido Introducción ………………………………………………………………………………….11 1. Descripción del problema ................................................................................................. 10 1.1. Problema educativo................................................................................................. 10 1.2. Formulación del problema ...................................................................................... 10 1.3. Objetivos de la investigación.................................................................................. 11 1.3.1. Objetivo General. ................................................................................................ 11 1.3.2. Objetivos Específicos.......................................................................................... 12 1.4. Justificación ............................................................................................................ 12 2. Marco teórico.................................................................................................................... 14 2.1. Antecedentes de la investigación............................................................................ 14 2.1.1. Investigaciones sobre el uso de AHD en la enseñanza ....................................... 14 2.1.2. Investigaciones relacionadas con el uso de las TIC en la solución de triángulos rectángulos. ........................................................................................................................... 15 2.2. Bases teóricas................................................................................................................ 15 2.2.1. Enfoque Pedagógico Socioconstructivista. ............................................................ 15 2.2.2. Características del socioconstructivismo ............................................................... 16 2.2.3. Las tareas del proceso educativo desde el Socioconstructivismo .......................... 18 2.2.4. Mediación............................................................................................................... 19 iv 2.2.5. Andamiaje .............................................................................................................. 19 2.2.6. Ayuda ajustada ....................................................................................................... 20 2.3. Zonas de desarrollo ....................................................................................................... 21 2.3.1. Zona de Desarrollo Próximo (ZDP)....................................................................... 22 2.3.2. Nivel Real de Desarrollo (NRD)............................................................................ 22 2.3.3. Nivel Potencial de Desarrollo (NPD)..................................................................... 22 2.3.4 Construcción de significados compartidos.............................................................. 24 2.3.5 Procesos de Internalización..................................................................................... 25 2.3.6 Actividad conjunta .................................................................................................. 27 2.4. Teorías de aprendizaje................................................................................................... 27 2.4.1. Aprendizaje Autónomo .......................................................................................... 27 2.4.2 Aprendizaje Colaborativo ....................................................................................... 32 2.4.3. Aprendizaje Basado en Problemas. (ABP) ............................................................ 37 2.4.4 Saberes Tecnológicos y Pedagógicos del Contenido (TPACK) ............................. 40 2.4.5 The Knowledge Quartet (KQ)................................................................................. 41 2.4.6 Conocimiento didáctico del contenido.................................................................... 42 2.4.7 Ambientes de aprendizaje ....................................................................................... 46 2.4.8 Modelo Van Hiele................................................................................................... 48 2.4.9 Fases de aprendizaje del modelo de Van Hiele....................................................... 51 v 2.5. Las TIC en la enseñanza de matemáticas...................................................................... 54 2.5.1 La AHD como Sistema Hipermedia Adaptativo (SHA)......................................... 55 2.6. Material educativo en la enseñanza de matemáticas..................................................... 56 2.6.1. Características del material educativo digital........................................................ 57 2.6.2. Usos de Material Educativo ................................................................................... 59 2.6.3. Adaptación de material educativo.......................................................................... 60 2.6.4. Estrategias comunicativas...................................................................................... 62 2.7. Solución de triángulos rectángulos ............................................................................... 63 3. Metodología de la investigación ....................................................................................... 64 3.1. Diseño cualitativo descriptivo................................................................................. 64 3.2. Contexto de la investigación................................................................................... 65 3.3. Técnicas e instrumentos de investigación............................................................... 65 3.3.1 Técnica de observación participante ....................................................................... 65 3.3.2 Registros video-gráficos...................................................................................... 66 3.4. Diseño del modelo pedagógico para la solución de triángulos rectángulos en el aula de clase 67 3.5 Procedimiento............................................................................................................. 69 3.5.1 Fases, objetivos y actividades del estudio........................................................... 69 3.6 Diseño y creación de la AHD..................................................................................... 71 vi 3.6.1 Diseño de la Secuencia Didáctica (SD)............................................................... 72 3.7 Diseño y organización del ambiente de aprendizaje .................................................. 72 3.7.1 Contexto Físico ....................................................................................................... 73 3.7.2 Rol del estudiante ................................................................................................ 73 3.7.3 Rol del docente.................................................................................................... 74 3.8 Categorías de análisis................................................................................................. 75 3.8.1 Creación y adaptación de materiales educativos................................................. 75 3.8.2 Aplicación y uso de los recursos educativos de la AHD..................................... 77 3.8.3 Estrategias comunicativas (con herramientas de trabajo colaborativo, autónomo y basado en problemas)............................................................................................................ 77 3.9 Evaluación de la AHD................................................................................................ 77 3.10 Secuencia didáctica................................................................................................. 78 4. Análisis e interpretación de resultados ............................................................................. 79 4.1 Creación de material educativo .................................................................................. 79 5. Conclusiones..................................................................................................................... 80 5.1 Conclusión general......................................................................................................... 82 6. Referencias bibliográficas................................................................................................. 8

PVST, a tool to assess the power to volume scaling distortions associated to code simulations

System codes along with necessary nodalizations are valuable tools for thermal hydraulic safety analysis. In order to assess the safety of a particular power plant, in addition to the validation and veri cation of the code, the nodalization of the system needs to be quali ed. Since most existing experimental data come from tests performed on scaled-down facilities, any quali cation process must therefore address scale considerations. Along these lines, the Group of Thermal Hydraulic Studies at Technical University of Catalonia (GET) developed SCUP, a scaling-up methodology for qualifying full-scale nodalizations through a systematic procedure based on the extrapolation of post-test simulations of Integral Test Facilities (ITF) experiments. For that purpose, GET created thePostprint (author's final draft

Kv-scaling in thermal hydraulics: Background, applications and forthcoming uses

Addressing the scaling issue refers to a rather complex process of demonstrating the applicability of activities devoted to predict the behaviour of actual nuclear power plants using the knowledge acquired in scaled-down test facilities. Such activities involve, among others, the evaluation of the capability of Best Estimate codes to scale-up processes from reduced scale test facilities to full scale Nuclear Power Plants (NPP) and the quantification of the effects of scale distortions. In this context, a scaled calculation is a system-code simulation in which, defined test conditions of an Integral Test Facility (ITF) are scaled-up to a NPP nodalization to reproduce the same scenario. The practical use of such kind of calculation is to permit a comparison of the behaviour of the plant and the ITF nodalizations under the same conditions. The comparison between the NPP -scaled results and those of the experiment post-test calculation will show unavoidable differences or distortions. Explaining such distortions is the key process in methods devoted to qualify plant nodalizations. The aim of this paper is to show the effectiveness of -scaled calculations and to outline the forthcoming use of hybrid nodalizations and scale-up nodalizations. The paper includes a thorough literature review of these type of approaches as well as the perspectives of future use of the scaling analysis. Such future uses include the feedback to experimentation. Despite the fact that the hybrid calculations presented here are related to existing ITFs and NPPs, feedback to experimentation intents to show the essentials of a future practice to be mainly implemented in modular ITFs.Peer ReviewedPostprint (published version

Applying UPC scaling-up methodology to the LSTF-PKL counterpart test

In the framework of the nodalization qualification process and quality guarantee procedures and following the guidelines of Kv-scaled analysis and UMAE methodology, further development has been performed by UPC team resulting in a scaling-up methodology. Such methodology has been applied in this paper for analyzing discrepancies that appear between the simulations of two counterpart tests. It allows the analysis of scaling-down criterion used for the design of an ITF and also the investigation of the differences of configuration between an ITF and a particular NPP. For analyzing both, it applies two conceptsPostprint (published version

Methodology for phenomenological code assessment with integral test data

The use of codes in the licensing process requires a rigorous validation process that can be accomplished by means of qualitative and quantitative assessment. In thermal hydraulics, this validation has to be performed at different levels, from separate effects to the integral response of a plant design. Even though the quantitative assessment is preferred, for complex phenomenology involving the behaviour of the whole plant system this approach is difficult and the assessment is usually performed through qualitative expert judgement. In the present article, a methodology is proposed that combines the use of qualitative and quantitative adequacy assessment for the simulation of experiments at integral test facilities. The method makes use of statistical quantification by means of Best Estimate Plus Uncertainty calculations.Peer ReviewedPostprint (published version

Assessment of SBO Fukushima likewise scenario for an IPWR design with RELAP5MOD33 and RELAPSCDAPSIMMOD3. 5 codes

In recent years Small Modular Reactors (SMR) have become very popular within the nuclear industry. These designs allow to reduce costs as well as to enhance the safety due to passive nuclear safety features. Within these systems, the integral Pressurized Water Reactors (iPWR) are very extended because they take advantage of the previous technology developed for Gen II and III PWRs. In this sense, previous Best Estimate system codes like RELAP5 or CATHARE seem to be reliable for Deterministic Safety Assessment (DSA) but need to be assessed for new passive systems in which natural circulation takes a key role. In the present paper, Energy Software Ltd., in collaboration with the UPC, has developed an iPWR input model for both NRC RELAP5 and ISS RELAPSCDAPSIM codes. These models, based on CAREM-25 publicly available data, simulate an SBO Fukushima likewise scenario. Results under Design Basis Accident (DBA) conditions are benchmarked to assess the reliability of the codes to reproduce the plant availability reported in the collected data. Passive systems like Safety Injections and Residual Heat Removal Exchangers have also been included to analyze the code capabilities to reproduce natural circulation under iPWR conditions. Finally, core damage progression is simulated with SCDAP components to analyze the severe accident related phenomena. Results of both simulations seem to confirm the 36 hours grace period for SBO scenario of the CAREM-25 design plus the extended 36 hours grace period associated to the availability of Emergency Injection System (EIS) in Loss of Coolant conditions reported by designer.Peer ReviewedPostprint (published version

Turning light into a liquid via atomic coherence

We study a four level atomic system with electromagnetically induced transparency with giant $\chi^{(3)}$ and $\chi^{(5)}$ susceptibilities of opposite signs. This system would allow to obtain multidimensional solitons and light condensates with surface tension properties analogous to those of usual liquids