Efficient memory management in video on demand servers

In this article we present, analyse and evaluate a new memory management technique for video-on-demand servers. Our proposal, Memory Reservation Per Storage Device (MRPSD), relies on the allocation of a fixed, small number of memory buffers per storage device. Selecting adequate scheduling algorithms, information storage strategies and admission control mechanisms, we demonstrate that MRPSD is suited for the deterministic service of variable bit rate streams to intolerant clients. MRPSD allows large memory savings compared to traditional memory management techniques, based on the allocation of a certain amount of memory per client served, without a significant performance penaltyPublicad

Thermomagnetic detection of recrystallization in FeCoNbBCu nanocrystalline alloys

The recrystallization process in FeCoNbBCu nanocrystallinealloys is evidenced from thermomagnetic results as a significant decrease in magnetization at the second crystallization stage. The lowering in the volume fraction of α-FeCo crystals indicates that some of these crystals contribute to the boride phases formed. Electron microscopy images reveal that the final microstructure consists of large crystals (∼500 nm) of a fcc (FeCo)23B6(FeCo)23B6 phase and small crystals (∼20 nm) of bcc α-FeCo and of some boride phases as such (FeCo)2B

The Application of Business Process Model Notation to describe a Methodology for the Recognition, Tagging and Acknowledge of Informal Learning Activities

[EN] Learning is a process that takes place anywhere and at any moment of our life. That means that not all learning happens linked to an institution. However, that kind of learning, known as informal learning, is usually invisible for people in charge of organizations. This is because either the learner is not aware of having learned something or because he/she is not able to show or make visible this type of learning to other. In order to facilitate the exploitation of this knowledge, TRAILER project poses a methodology supported by a technological ecosystem. This methodology is quite complex; it involves different stakeholders and components. For defining the methodology, a flexible and understandable notation was used, Business Process Model Notation. It helps in the designing and implementation of the solution and it also has been used to guide experts during the methodology testing

Osteosarcoma perióstico: caso clínico

El osteosarcoma perióstico es un sarcoma raro que asienta en la superficie del hueso. Aunque algunos autores lo incluyen en los osteosarcomas yuxtacorticales sus peculiaridades clínicas, radiológicas y anatomopatológicas entre ellos que llevan a diferencias en el tratamiento y pronóstico le otorgan personalidad propia. Presentamos un caso clínico de osteosarcoma perióstico en un varón de 18 años, a nivel de fémur. Se realiza una revisión de la bibliografía, señalando las principales características de esta entidad.Periosteal osteosarcoma is a rare malignant neoplasm located on bone surface. Although some authors include it among juxtacortical osteosarcoma, its clinical feature, imaging studies findings and histologic patterns which lead to differences in the treatment and prognostic, give to it a peculiar identity. We report a case of an 18 years old man who had this tumour in his femur. We do a review of literature

RoboSTEAM Project Systematic Mapping: Challenge Based Learning and Robotics

STEAM Education is nowadays a key element for our current digital society. Integrating STEAM and developing competences such as Computational Thinking is highly demanded by the industry and higher education institutions. In order to do so new methodological approaches are required. RoboSTEAM project is an Erasmus+ project defined to address these topics by using of physical devices and robotics employing Challenge Based Learning methodology. One of the first steps in the project development is the definition of current landscape in the research field. Which means to carry out a literature mapping that considers previous applications of Challenge Based Learning in STEAM education and use of robots and physical devices to do so. This paper shows the mapping review process and the main results obtained. The mapping analyze 242 candidate works from the most relevant bibliographic sources and selected 54. Form them it was possible to see that there are not many initiatives on STEM Education related to Challenge base learning and the most of them are specially focused on the application of specific tools and in the development of concrete competences

Your Teammate Just Sent You a New Message! The Effects of Using Telegram on Individual Acquisition of Teamwork Competence

Students’ acquisition of teamwork competence has become a priority for educational institutions. The development of teamwork competence in education generally relies in project-based learning methodologies and challenges. The assessment of teamwork in project-based learning involves, among others, assessing students’ participation and the interactions between team members. Project-based learning can easily be handled in small-size courses, but course management and teamwork assessment become a burdensome task for instructors as the size of the class increases. Additionally, when project-based learning happens in a virtual space, such as online learning, interactions occur in a less natural way. This study explores the use of instant messaging apps (more precisely, the use of Telegram) as team communication space in project-based learning, using a learning analytics tool to extract and analyze student interactions. Further, the study compares student interactions (e.g., number of messages exchanged) and individual teamwork competence acquisition between traditional asynchronous (e.g., LMS message boards) and synchronous instant messaging communication environments. The results show a preference of students for IM tools and increased participation in the course. However, the analysis does not find significant improvement in the acquisition of individual teamwork competence

Clasificación visual de madera estructural de pino laricio (Pinus nigra Arn.): comparación de resultados usando las normas UNE 56.544 y DIN 4074

On a 776 boards sample of Pinus nigra 150 X 50 X 3.000 mm size, coming from felled trees in Jaen (Spain) a comparison of results is made using two different standards of visual strength grading, the German DIN 4074, usually employed within Europe, and the recent Spanish UNE 56544. Graded the same batch of timber by means of both standards, the yields and the physico-mechanical properties of every grade are calculated. The physico-mechanical properties of timber (density, bending strength and modulus of elasticity) are studied by testing according to the methodology included in the European standard EN 408, calculating the results according to the standard EN 384 and assigning the strength classes according to EN 338. The results lead to the conclusion that the use of the Spanish standard produces almost the same results than the use of the German standard, not only as far as the yields are concerned but also regarding the physico-mechanical properties of timber. In this way a second conclusion is reached, the Spanish standard follows criteria and produces results commonly accepted by the market.Sobre una muestra de 776 tablones de Pinus nigra Arn. de dimensiones 150 X 50 X 3.000 mm, procedentes todos ellos de árboles cortados en Jaén (España), se efectúa una comparación de resultados empleando dos normas de clasificación visual de la madera aserrada con destino estructural, la norma alemana DIN 4074, habitualmente empleada en el seno de Europa y la norma española, de muy reciente introducción, la UNE 56.544. Clasificado el mismo lote de madera por ambas normas, se determinan los rendimientos clasificatorios y las características físico-mecánicas de la madera agrupada en cada clase de calidad La determinación de las propiedades físico-mecánicas de la madera (densidad, Resistencia a la flexión y Módulo de elasticidad) se efectúa haciendo uso de la metodología contenida en la norma europea EN 408, calculando los valores de resistencia según la norma EN 384 y asignando las clases de resistencia según lo establecido en la norma EN 338. Los resultados habidos reflejan que el uso de la norma española lleva a resultados similares a los de la norma alemana, tanto en rendimientos como en resistencia, motivo por lo cual se considera que la susodicha norma española sigue unos criterios aceptados y muy arraigados en el mercado

Mejora de la predicción de la resistencia y rigidez de la madera estructural con el método de ultrasonidos combinado con parámetros de clasificación visual

The present study explores the possibility of using longitudinal ultrasound transmission to evaluate the bending strength and modulus of elasticity in structural timber made from the two species most commonly found in Spanish construction and rehabilitation works: Scots pine (Pinus sylvestris L.) and Laricio pine (Pinus nigra Arn.). An analysis of 1305 Scots pine and 852 Laricio pine beams shows that ultrasound transmission velocity alone can predict neither the bending strength nor the modulus of elasticity and that other predictive variables are required.A series of models are proposed based on ultrasound transmission velocity measurements, the relative size of the largest face and edge knots, length and density. After running models for each species individually and for the two jointly, a single model is found to be suitable for both. The models proposed explain from 63 to 73 per cent of bending strength and modulus of elasticity variability.Se analiza la posibilidad de aplicar la técnica de transmisión longitudinal de ultrasonidos para la evaluación de la resistencia y módulo de elasticidad a flexión de la madera estructural de las dos especies de mayor interés constructivo y más amplia presencia en obras de rehabilitación: el pino silvestre (Pinus sylvestris L.) y el pino laricio (Pinus nigra Arn.). Trabajando sobre un total de 1.305 vigas de pino silvestre y 852 de pino laricio se concluye que por sí sola la velocidad de transmisión de ultrasonidos no es un buen predictor ni de la resistencia ni del módulo de elasticidad en flexión, necesitando el complemento de otras variables predictoras. Se proponen diversos modelos basados en la medición de la velocidad de transmisión de ultrasonidos, de los diámetros relativos del nudo máximo de cara y de canto, de la longitud y de la densidad. Los modelos se proponen tanto a nivel especie como global, comprobándose que es posible emplear un modelo único para ambas especies. Los modelos propuestos son capaces de explicar entre el 63 y el 73% de la variabilidad de la resistencia y módulo de elasticidad a flexión