Collaborative Development within Open Source Communities

Open source communities are one of the most successful-- and least appreciated--examples of high-performance collaboration and community building on the Internet today. Open source communities began as loosely organized, ad-hoc communities of contributors from all over the world who shared an interest in meeting a common need. However, the organization of these communities has proven to be very flexible and capable of carrying out all kind of developments, ranging from minor projects to huge programs such as Apache (Höhn, & Herr, 2004; Mockus, Fielding, & Herbsleb, 2005

La Exposición Iberoamericana de Sevilla : La fase crítica de los primeros logros (1914-1922)

Tomo I ; págs. 67-8

Numerical simulation of a supersonic ejector for vacuum generation with explicit and implicit solver in openfoam

Supersonic ejectors are used extensively in all kind of applications: compression of refrigerants in cooling systems, pumping of volatile fluids or in vacuum generation. In vacuum generation, also known as zero-secondary flow, the ejector has a transient behaviour. In this paper, a numerical and experimental research of a supersonic compressible air nozzle is performed in order to investigate and to simulate its behaviour. The CFD toolbox OpenFOAM 6 was used, with two density-based solvers: explicit solver rhoCentralFoam, which implements Kurganov Central-upwind schemes, and implicit solver HiSA, which implements the AUSM+up upwind scheme. The behaviour of the transient evacuation ranges between adiabatic polytropic exponent at the beginning of the process and isothermal at the end. A model for the computation of the transient polytropic exponent is proposed. During the evacuation, two regimes are encountered in the second nozzle. In the supercritic regime, the secondary is choked and sonic flow is reached. In the subcritic regime, the secondary flow is subsonic. The final agreement is good with the two different solvers, although simulation tends to slightly overestimate flow rate for large values region.Peer ReviewedPostprint (published version

Factores que intervienen en el rendimiento académico de los estudiantes de la Facultad Multidisciplinaria Oriental, periodo del ciclo I-2014.

El propósito fundamental de la investigación que se realizó es el de dar a conocer cuáles son los principales determinantes del rendimiento académico de los estudiantes de pregrado de la Facultad Multidisciplinaria Oriental (FMO). El rendimiento académico en los estudiantes tiene una manifestación concreta en las calificaciones obtenidas las cuales hacen posible la aprobación o reprobación de las asignaturas y consecuentemente coronar con éxito la carrera o en su defecto el abandono de esta última. En cuanto a los factores que inciden en el rendimiento académico la investigación priorizó los aspectos que están relacionados con los servicios institucionales que la FMO facilita, con la función docente y con el interés y la motivación personal de los estudiantes. La investigación fue de tipo exploratoria descriptiva y se trabajó con un diseño metodológico de carácter mixto; con un enfoque dominante de carácter cualitativo. El estudio se apoyó en técnicas cuantitativas especialmente se aplicó un cuestionario a una muestra de estudiantes. Entre los principales resultados o hallazgos encontrados están: El Coeficiente de Unidades de Mérito (CUM) de la mayoría de estudiantes de la muestra está entre 6.0 (seis punto cero), 8.0 (ocho punto cero), la mayoría curso asignaturas en primera matrícula, en la investigación se encontró que son las actitudes y prácticas de los estudiantes las que determinan el rendimiento académico de los estudiantes así como también los problemas familiares, la frecuencia más alta de opiniones responden que la flexibilidad es una característica más común en los profesores de la FMO, que la experiencia de estos también incide en el rendimiento y los resultados académicos

Intelligent Garbage Classifier

IGC (Intelligent Garbage Classifier) is a system for visual classification and separation of solid waste products. Currently, an important part of the separation effort is based on manual work, from household separation to industrial waste management. Taking advantage of the technologies currently available, a system has been built that can analyze images from a camera and control a robot arm and conveyor belt to automatically separate different kinds of waste

dislib: large scale high performance machine learning in Python

In recent years, machine learning has proven to be an extremely useful tool for extracting knowledge from data. This can be leveraged in numerous research areas, such as genomics, earth sciences, and astrophysics, to gain valuable insight. At the same time, Python has become one of the most popular programming languages among researchers due to its high productivity and rich ecosystem. Unfortunately, existing machine learning libraries for Python do not scale to large data sets, are hard to use by non-experts, and are difficult to set up in high performance computing clusters. These limitations have prevented scientists from exploiting the full potential of machine learning in their research. In this work, we present dislib [1], a distributed machine learning library on top of PyCOMPSs programming model [2] that addresses the issues of other similar existing libraries

Modelling flexible thrust performance for trajectory prediction applications in ATM

Reduced thrust operations are of widespread use nowadays due to their inherit benefits for engine conservation. Therefore, in order to enable realistic simulation of air traffic management (ATM) scenarios for purposes such as noise and emissions assessment, a model for reduced thrust is required. This paper proposes a methodology for modelling flexible thrust by combining an assumed temperature (AT) polynomial model identified from manufacturer take-off performance data and public thrust models taken from typical ATM performance databases. The advantage of the proposed AT model is that it only depends on the take-off conditions —runway length, airport altitude, temperature, wind, etc. The results derived from this methodology were compared to simulation data obtained from manufacturer’s take-off performance tools and databases. This comparison revealed that the polynomial model provides AT estimations with sufficient accuracy for their use in ATM simulation. The Base of Aircraft Data (BADA) and the Aircraft Noise and Performance (ANP) database were chosen as representative of aircraft performance models commonly used in ATM simulation. It was observed that there is no significant degradation of the overall accuracy of their thrust models when using AT, while there is a correct capture of the corresponding thrust reduction.Peer ReviewedPostprint (published version

Recombinant Listeria monocytogenes expressing a cell wall-associated listeriolysin O is weakly virulent but immunogenic

Listeriolysin O (LLO) is an essential virulence factor for the gram-positive bacterium Listeria monocytogenes. Our goal was to determine if altering the topology of LLO would alter the virulence and toxicity of L. monocytogenes in vivo. A recombinant strain was generated that expressed a surface-associated LLO (sLLO) variant secreted at 40-fold-lower levels than the wild type. In culture, the sLLO strain grew in macrophages, translocated to the cytosol, and induced cell death. However, the sLLO strain showed decreased infectivity, reduced lymphocyte apoptosis, and decreased virulence despite a normal in vitro phenotype. Thus, the topology of LLO in L. monocytogenes was a factor in the pathogenesis of the infection and points to a role of LLO secretion during in vivo infection. The sLLO strain was cleared by severe combined immunodeficient (SCID) mice. Despite the attenuation of virulence, the sLLO strain was immunogenic and capable of eliciting protec-tive T-cell responses. Listeria monocytogenes is a gram-positive facultative intra-cellular pathogen extensively used to understand host-patho-gen interactions (44, 51, 53). It expresses the highly conserved pore-forming toxin listeriolysin O (LLO), a member of a large family of cholesterol-dependent cytolysins found in many im