Primer Encuentro Conjunto RSME-UMA, Buenos Aires, 11 a 15 de diciembre de 2017

En la semana del lunes 11 al viernes 15 de diciembre de 2017 se llevó a cabo en Buenos Aires el Primer Encuentro Conjunto entre la Unión Matemática Argentina (UMA) y la RSME. Se celebraba el centenario de la primera visita del Profesor Don Julio Rey Pastor a la Argentina, el punto de partida del estrecho vínculo que desde entonces ha existido entre las comunidades matemáticas de ambos países. El encuentro, que convocó a unos 900 participantes, se organizó alrededor de tres ejes principales: Actividades Científicas, Educación, y Divulgación. Las dos primeras se desarrollaron en el predio de la Facultad de Ciencias Exactas y Naturales de la Universidad de Buenos Aires, mientras que las actividades de divulgación, dirigidas a un pú- blico general, se llevaron a cabo en el amplio Centro Cultural de la Ciencia. Pueden consultarse los detalles, incluida la composición de los Comités Organizador y Científico, en la web del congreso: http://uma2017.dm.uba.ar

The Journal of the Friends' Historical Society vol. 26

Los sistemas de computación de alto rendimiento (HPC) continúan creciendo exponencialmente en términos de cantidad y densidad de componentes para lograr mayor potencia de cálculo. Al mismo tiempo, cloud computing se está volviendo popular, ya que las características clave tales como escalabilidad, pay-per-use y alta disponibilidad continúan evolucionando. También se está convirtiendo en una plataforma competitiva para ejecutar aplicaciones paralelas HPC debido al rendimiento cada vez mayor de instancias virtualizadas y de alta disponibilidad. Sin embargo, aumentar la cantidad de componentes para crear sistemas más grandes tiende a incrementar la frecuencia de fallos tanto en clústeres como en cloud. Hoy en día, los sistemas HPC tienen una tasa de fallos de alrededor de 1000 por año, lo que significa un fallo cada aproximadamente 8 horas. La mayoría de las aplicaciones paralelas distribuidas se construyen sobre una interfaz de paso de mensajes (MPI). Las implementaciones MPI siguen una semántica fail-stop predeterminada, que aborta la ejecución en caso de fallos de host en un clúster. En este caso, el propietario de la aplicación debe reiniciar la ejecución, lo que afecta el tiempo total esperado del mismo y, además, el costo, ya que requiere adquirir más recursos durante periodos de tiempo más largos. Las técnicas de Tolerancia a Fallos (TF) deben aplicarse a las ejecuciones paralelas de MPI tanto en clúster como en cloud. Con las técnicas de TF, se garantiza una alta disponibilidad para aplicaciones paralelas. Para aplicar algunas soluciones de TF, se requieren privilegios de administrador para instalarlas en los nodos del clúster. Además, cuando aparecen fallos, se requiere intervención humana para reiniciar la aplicación. Se prefiere una solución que minimice la intervención de usuarios y administradores. Una contribución de esta tesis es un Fault Tolerance Manager (FTM) para checkpoints coordinados, que proporciona a los usuarios la recuperación automática de fallos al perder nodos de clúster. FTM aprovecha el almacenamiento local en los nodos para guardar los checkpoints, y distribuye sus copias entre los nodos de computo, evitando el cuello de botella de un almacenamiento centralizado. También aprovechamos FTM para utilizar protocolos de rollback-recovery no-coordinados y semi-coordinados. En esta contribución, FTM se implementa en la capa de aplicación. Además, se agrega un controlador dinámico de recursos al FTM, que monitoriza el uso de recursos destinados para la protección FT y realiza acciones para mantener un nivel aceptable de protección. Otra contribución apunta a la configuración de tareas de protección y recuperación de la TF. Se presentan dos modelos: el modelo First Protection Point (FPP) determina el punto de partida para introducir la protección de TF de modo a obtener beneficios en términos de tiempo total de ejecución, incluyendo fallos, eliminando checkpoints innecesarios. El segundo modelo permite mejorar la configuración de recursos de la TF para la tarea de recuperación. Con respecto a entornos cloud, proponemos Resilience as a Service (RaaS), un servicio que provee TF para aplicaciones HPC, que utiliza FTM. RaaS proporciona al cloud un servicio de TF distribuido, escalable y altamente disponible. Rediseña los mecanismos tradicionales de protección y recuperación de HPC, para aprovechar de forma nativa las capacidades del cloud y sus múltiples alternativas para implementar tareas de TF. En resumen, esta tesis contribuye a proporcionar un gestor de tolerancia a fallos multi-plataforma “Multi-Platform Resilience Manager” (MRM), adecuado para entornos de clústers y clouds (públicos y privados). La solución presentada proporciona TF de forma automática, distribuida y transparente en las capas de aplicación y usuario según los requisitos de usuarios, aplicaciones y entorno de ejecución. Brinda además, a los usuarios información crítica de la TF, lo que les permite compensar entre costos y protección, manteniendo el tiempo medio de reparación dentro de rangos aceptables. Durante las validaciones experimentales se utilizaron varios entornos experimentales, como clústeres tradicionales y cloud (públicos y privados), ejecutando diferentes aplicaciones paralelas. Los experimentos verifican la funcionalidad y la mejora de las contribuciones. Además, también muestran que el tiempo medio de reparación se encuentra limitado y dentro de rangos aceptables.High Performance Computing (HPC) systems continue growing exponentially in terms of components quantity and density to achieve demanding computational power. At the same time, cloud computing is becoming popular, as key features such as scalability, pay-per-use and availability continue to evolve. It is also becoming a competitive platform for running parallel HPC applications due to the increasing performance of virtualized, highly-available instances. Although, augmenting the amount of components to create larger systems tends to increment the frequency of failures in both clusters and cloud environments. Nowadays, HPC systems have a failure rate of around 1000 per year, meaning a failure every approximately 8 hours. Most of the parallel distributed applications are built on top of a Message Passing Interface (MPI). MPI implementations follow a default fail-stop semantic, which aborts the execution in case of host failure in a cluster. In this case, the application owner needs to restart the execution, which affects the wall clock time and, also, the cost since it requires to acquire computing resources for longer periods of time. Fault Tolerance (FT) techniques need to be applied to MPI parallel executions in both, cluster and cloud environments. With FT techniques, high availability is ensured for parallel applications. In order to apply some FT solutions, administrator privileges are required, to install them in the cluster nodes. Moreover, when failures appear human intervention is required to recover the application. A solution, which minimizes users and administrators intervention is preferred. A contribution of this thesis is a Fault Tolerance Manager (FTM) for coordinated checkpoint, which provides the application's users with automatic recovery from failures when losing computing nodes. It takes advantage of node local storage to save checkpoints, and it distributes copies of them along all the computation nodes, avoiding the bottleneck of a central stable storage. We also leverage the FTM to use uncoordinated and semi-coordinated rollback recovery protocols. In this contribution, FTM is implemented in the application-layer. Furthermore, a dynamic resource controller is added to the FTM, which monitors the FT protection resource usage and performs actions to maintain an acceptable level of protection. Another contribution aims to the FT protection and recovery tasks configuration. Two models are introduced. The First Protection Point model (FPP) determines the starting point to introduce FT protection gaining benefits in terms of total execution time including failures, by removing unnecessary checkpoints. The second model allows improving the FT resource configuration for the recovery task. Regarding cloud environments, we propose Resilience as a Service (RaaS), a fault tolerant framework for HPC applications, which uses FTM. RaaS provides clouds with a highly available, distributed and scalable fault-tolerant service. It redesigns traditional HPC protection and recovery mechanisms, to natively leverage cloud capabilities and its multiple alternatives for implementing FT tasks. To summarize, this thesis contributes on providing a multi-platform resilience manager, suitable for traditional baremetal clusters and clouds (public and private). The presented solution provides FT in an automatic, distributed and transparent manner in the application and user levels according to the users, applications, and runtime requirements. It gives the users critical FT information, allowing them to trade-off cost and protection keeping the mean time to repair within acceptable ranges. Several experimental environments such as bare-metal clusters and cloud (public and private), running different parallel applications were used during the experimental validations. The experiments verify the functionality and improvement of the contributions. Moreover, they also show that the Mean Time To Repair is bounded within acceptable ranges

Optimal combination and reference functions of signal-to-noise measurements for GNSS multipath detection

[EN] Multipath is the most limiting factor in many GNSS positioning applications, where it inevitably degrades the attainable precision. Among the different proposals to identify observations affected by multipath, Strode and Groves have recently proposed a method based on the comparison of GPS signal-to-noise (SNR) actual measurements with suitable reference functions previously computed in a low-multipath environment. We have found significant issues with its application to our particular GNSS experiments, however. In particular, we discuss whether the reference functions that are needed to be computed for low-multipath environments after tedious and time consuming field campaigns can be used for a future occasion, or not, as well as the possibility of applying the method to other GNSS global constellations (Galileo and GLONASS). Additionally, we elaborate on an alternative idea consisting in the use of the best combination of SNR measurements for the different signals in the different constellations in order to obtain a multipath estimator that is unbiased, universal and performs better than the use of reference functions.Pánik, P.; García-Asenjo Villamayor, L.; Baselga Moreno, S. (2019). Optimal combination and reference functions of signal-to-noise measurements for GNSS multipath detection. Measurement Science and Technology. 30(4):1-13. https://doi.org/10.1088/1361-6501/ab05aeS11330

Conversión entre coordenadas geodésicas y coordenadas locales

En este artículo se aborda la conversión entre coordenadas geodésicas y coordenadas expresadas en un sistema cartesiano local, tanto en sentido directo como recíproco. La solución planteada está basada exclusivamente en conversiones de coordenadas, rotaciones y traslaciones, por lo que mantiene intacta la geometría relativa de los puntos.García-Asenjo Villamayor, L. (2017). Conversión entre coordenadas geodésicas y coordenadas locales. http://hdl.handle.net/10251/84060DE

Development of a Submillimetric GNSS-Based Distance Meter for Length Metrology

[EN] Absolute distance determination in the open air with an uncertainty of a few tenths of a millimetre is increasingly required in many applications that involve high precision geodetic metrology. No matter the technique used to measure, the resulting distances must be proven consistent with the unit of length (SI-metre) as realized in the outdoor facilities traditionally used in length metrology, which are also known as calibration baselines of reference. The current calibration baselines of reference have distances in the range of 10 to 1000 m, but at present there is no solution on the market to provide distances with submillimetric precision in that range. Consequently, new techniques such as multi-wave interferometry, two-wave laser telemeters or laser trackers are being developed. A possible alternative to those sophisticated and expensive techniques is the use of widely used Global Navigation Satellite Systems (GNSS) in order to provide a GNSS-Based Distance Meter (GBDM). The use of a GBDM as a potential technique for length metrology has been thoroughly analysed in several European research projects by using the state-of-the-art geodetic software, such as Bernese 5.2, but no definite conclusions have been drawn and some metrological questions are considered still open. In this paper, we describe a dedicated approach to build up a submillimetric GBDM able to be applied in the current calibration baselines of reference, as well as possible methods to cope with the multipath error of the GNSS signals which is the major limitation for the practical uptaking of the technique in metrology. The accuracy of the proposed approach has been tested following the length metrology standards in four experiments carried out in the Universitat Politecnica de Valencia (UPV). The results demonstrate that the proposed GBDM can provide an accuracy of a few tenths of a millimetre in the current calibration baselines of referenceThis work was partly performed within the 18SIB01 GeoMetre project of the European Metrology Programme for Innovation and Research (EMPIR). This project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. This research was also partly funded by the Spanish Ministry of Education, Culture and Sports (PRX17/00371).García-Asenjo Villamayor, L.; Baselga Moreno, S.; Atkins, C.; Garrigues Talens, P. (2021). Development of a Submillimetric GNSS-Based Distance Meter for Length Metrology. Sensors. 21(4):1-21. https://doi.org/10.3390/s2104114512121

GBDM+: an improved methodology for a GNSS-based distance meter

[EN] The determination of distances consistent with the definition of the base unit of length in the International System of Units (SI), the SI meter, with uncertainties of less than 1 ppm up to 5 km in the open air is a current challenge that is being increasingly required for different applications, including the determination of local ties, calibration baselines, and high precision geodetic metrology in singular scientific and engineering projects. The required knowledge of the index of refraction of the propagating medium at the same level of 1 ppm is a hard limit to the use of precise electronic distance meters (EDMs), which has motivated the recent development of new two-color, refractivity compensated, EDM prototypes. As an alternative, the use of global navigation satellite systems (GNSS) could benefit from their high scale stability although the lack of appropriate estimation of the uncertainties in their sources of error and their unknown propagation into the final result during the data processing has prevented a rigorous uncertainty analysis and, therefore, the use of GNSS for absolute distance determination. Stemming from our initial methodology for a GNSS-based distance meter (GBDM) that was restricted to relatively horizontal baselines and distances up to 1 km only, we have improved the method so that its application range is extended to baselines of up to 5 km with a possibly significant height difference so that it provides the final baseline distance with the corresponding uncertainty derived from the uncertainties in the different error sources rigorously propagated through the equations by which the distance is finally determined. This improved methodology, named as GBDM+, constitutes a significant step forward in the application of GNSS to open air length metrology.The work leading to this paper was performed within the 18SIB01 GeoMetre project of the European Metrology Programme for Innovation and Research (EMPIR). This project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme, funder ID: 10.13039/100014132. Raquel Lujan acknowledges the funding from the Programa de Ayudas de Investigacion y Desarrollo (PAID-01-20) de la Universitat Politecnica de Valencia.Baselga Moreno, S.; García-Asenjo Villamayor, L.; Garrigues Talens, P.; Luján, R. (2022). GBDM+: an improved methodology for a GNSS-based distance meter. Measurement Science and Technology. 33(8):1-16. https://doi.org/10.1088/1361-6501/ac6f4511633

Sex separation unveils the functional plasticity of the vomeronasal organ in rabbits

Chemosensory cues are vital for social and sexual behaviours and are primarily detected and processed by the vomeronasal system (VNS), whose plastic capacity has been investigated in mice. However, studying chemosensory plasticity outside of laboratory conditions may give a more realistic picture of how the VNS adapts to a changing environment. Rabbits are a well-described model of chemocommunication since the discovery of the rabbit mammary pheromone and their vomeronasal organ (VNO) transcriptome was recently characterised, a first step to further study plasticity-mediated transcriptional changes. In this study, we assessed the plastic capacity of the rabbit male and female VNO under sex-separation vs. sex-combined scenarios, including adults and juveniles, to determine whether the rabbit VNO is plastic and, if so, whether such plasticity is already established at early stages of life. First, we characterised the number of differentially expressed genes (DEGs) between the VNO of rabbit male and female under sex-separation and compared it to sex-combined individuals, both in adults and juveniles, finding that differences between male and female were larger in a sex-separated scenario. Secondly, we analysed the number of DEGs between sex-separated and sex-combined scenarios, both in males and females. In adults, both sexes showed a high number of DEGs while in juveniles only females showed differences. Additionally, the vomeronasal receptor genes were strikingly downregulated in sex-separated adult females, whereas in juveniles upregulation was shown for the same condition, suggesting a role of VRs in puberty onset. Finally, we described the environment-modulated plastic capacity of genes involved in reproduction, immunity and VNO functional activity, including G-protein coupled receptors. Our results show that sex-separation induces sex- and stage-specific gene expression differences in the VNO of male and female rabbit, both in adults and juveniles. These results bring out for the first time the plastic capacity of the rabbit VNO, supporting its functional adaptation to specifically respond to a continuous changing environment. Finally, species-specific differences and individual variability should always be considered in VNO studies and overall chemocommunication research

Assignment Problems in Wildfire Suppression: Models for Optimization of Aerial Resource Logistics

This is a pre-copyedited, author-produced version of an article accepted for publication in Forest Science following peer review. The version of record Rodríguez-Veiga, J., Gómez-Costa, I., Ginzo-Villamayor, M., Casas-Méndez, B., & Sáiz-Díaz, J. (2018). Assignment Problems in Wildfire Suppression: Models for Optimization of Aerial Resource Logistics. Forest Science, 64(5), 504-514 is available online at: https://doi.org/10.1093/forsci/fxy012Wildfire containment activities involve a combination of important decisions that affect the evolution of the fire and effective resource deployment. When aerial resources (in particular aircraft and helicopters) are used, two tasks are assigned to the aerial coordinator: the allocation of aerial resources to flight routes (circular paths that aerial resources follow such that they have common loading and discharge points) and refueling points. In this paper, we introduce two models of linear integer programming to execute these tasks. The models are written using AMPL and the Gurobi solver engine and illustrated through examples. The objective of these models is to provide automatic and rapid support for the coordination of the abovementioned tasks. In order to enhance the robustness of the models, the scheduling times and the characteristics of the aerial resources are also considered. These models aim at minimizing both the containment time of the fire and the total flight hours. The models will reduce the risk of aerial collision of resources by taking into account the maximum number of aerial resources that can simultaneously load water at the same point. Moreover, management of refueling points is also achievedThis research received financial support from the Ministerio de Economía y Competitividad of Spain through grant MTM2014-53395-C3-2-P, MTM2016-76969-P, MTM2017-87197-C3-3-P, and from ITMATI, Technological Institute of Industrial Mathematics, Santiago de Compostela, Spain, through the Enjambre projectS

Evaluation of Long-Range Mobile Mapping System (MMS) and Close-Range Photogrammetry for Deformation Monitoring. A Case Study of Cortes de Pallás in Valencia (Spain)

none8openDi Stefano, Francesco; Cabrelles, Miriam; García-Asenjo, Luis; Lerma, José Luis; Malinverni, Eva Savina; Baselga, Sergio; Garrigues, Pascual; Pierdicca, RobertoDi Stefano, Francesco; Cabrelles, Miriam; García-Asenjo, Luis; Lerma, José Luis; Malinverni, Eva Savina; Baselga, Sergio; Garrigues, Pascual; Pierdicca, Robert

Design of an Intelligent Front-End Signal Conditioning Circuit for IR Sensors

This paper presents the design of an intelligent front-end signal conditioning system for IR sensors. The system has been developed as an interface between a PbSe IR sensor matrix and a TMS320C67x digital signal processor. The system architecture ensures its scalability so it can be used for sensors with different matrix sizes. It includes an integrator based signal conditioning circuit, a data acquisition converter block, and a FPGA based advanced control block that permits including high level image preprocessing routines such as faulty pixel detection and sensor calibration in the signal conditioning front-end. During the design phase virtual instrumentation technologies proved to be a very valuable tool for prototyping when choosing the best A/D converter type for the application. Development time was significantly reduced due to the use of this technology