Organizaciones virtuales y redes neuronales. Algunas similitudes.

Aunque existen numerosos trabajos que identifican sus principales características y modo de funcionamiento, el estudio de las organizaciones virtuales adolece de una carencia de modelos matemáticos que reflejen su comportamiento de un modo cuantitativo. En este sentido, a lo largo del presente trabajo se tratará de poner de manifiesto las similitudes existentes entre el funcionamiento de las organizaciones virtuales y el de las redes neuronales (SOM, SelfOrganizing Maps). El objetivo es sentar las bases para proponer este tipo de técnica estadística como herramienta para la formulación de modelos sobre organizaciones virtuales. Se plantearán una serie de argumentos de plausibilidad, dejando a investigaciones posteriores la verificación rigurosa de esta propuesta.ORGANIZACION VIRTUAL, REDES SOM, MAPAS DE KOHONEN

TOURISTS’ MEANING OF SUSTAINABILITY AS A TOOL FOR SEGMENTATION. A BIOSPHERE RESERVE CASE STUDY

This paper provides empirical evidence on the potential use of the meaning of sustainability for the tourist in segmentation studies. The analysis has been applied to a nature destination, specifically, in the “Sierras de Cazorla, Segura y Las Villas” Biosphere Reserve. In the first place, this research identifies, through a cluster analysis, three segments of tourists based on what the tourist considers sustainability to be (level of knowledge and commitment, as well as its implications for the destination), analyzing for each segment their sociodemographic and socioeconomic variables and their willingness to pay to improve the sustainability of destinations. The results show that it is possible to identify one or several segments of demand that show different levels of commitment, attitude, knowledge and/or behavior towards sustainability and calculate the amount of money that each segment is willing to pay to visit a more sustainable destination. This research shows, however, that more than 70% of those surveyed are not willing to pay more to achieve a more sustainable destination, the reasons being very diverse, but, in any case, no significant differences being identified between the segments with respect to this question. The study concludes by discussing the potential of using the meaning of sustainability for the tourist as an important segmentation tool, aimed at facilitating the change towards a more sustainable tourism behavior, and allowing the design of pro-sustainable strategies and policies in tourist destinations

Tourism stock price and COVID-19: medium-term relationship with passenger transport, hotel, and tour operator subsectors

COVID-19 has had a devastating effect on tourism in Spain, one of the world’s biggest tourist destinations and also one of the first countries to face the consequences of the pandemic. Tourism stock prices showed high volatility at the beginning of the pandemic. However, we do not yet know whether this relationship has remained throughout the pandemic and the effect it has had on the main subsectors of tourism. Quantifying this relationship in the medium term makes it possible to predict the effect of the pandemic on the tourism sector stock market and to compare the impact on its different subsectors. A dynamic regression model has been developed to predict the stock price of the hotel, passenger transport, and tour operator subsectors in Spain, based on the evolution of COVID-19. Cumulative COVID-19 deaths have been confirmed to be a good predictor of abnormal stock price in the main tourism subsectors, affecting passenger transport more intensely than hotels or tour operators

A new approach to optimize the energy efficiency of CO2 transcritical refrigeration plants

This paper proposes a model-free real-time optimization and control strategy for CO2 transcritical refrigeration plants that assures covering the cooling demand and continuous tracking of conditions for maximum efficiency. Our approach obtains the feedback with only three measurements, and controls the opening degree of a backpressure valve and the speed of the compressor. The strategy minimizes the power consumption of the compressor instead of maximizing the coefficient of performance, which avoids several sensors, and we demonstrate mathematically that both approaches are equivalent. We implemented the strategy with an algorithm that includes two independent auto tuned controllers, one devoted to regulate the high-pressure and another to regulate the outlet temperature of the secondary fluid of the evaporator. It also incorporates a real time perturb and observe procedure to locate online the optimum high-pressure that minimizes the compressor power consumption. The paper presents the experimental evaluation of the control strategy, verifying the stable operation of the algorithm and the energy optimization of the plant

AR drone identification and navigation control at CVG-UPM

This article presents the proposal of the Computer Vision Group to the first phase of the international competition “Concurso de Ingeniería de Control 2012, Control Aut ́onomo del seguimiento de trayectorias de un vehículo cuatrirrotor”. This phase consists mainly of two parts: identifying a model and designing a trajectory controller for the AR Drone quadrotor. For the identification task, two models are proposed: a simplified model that captures only the main dynamics of the quadrotor, and a second model based on the physical laws underlying the AR Drone behavior. The trajectory controller design is based on the simplified model, whereas the physical model is used to tune the controller to attain a certain level of robust stability to model uncertainties. The controller design is simplified by the hypothesis that accurate positions sensors will be available to implement a feedback controller

Análisis de la cadena de valor del sector eólico en Castilla y León

El sector eólico se ha convertido en una de las principales actividades productivas de Castilla y León. De hecho, es el principal generador de esta energía del país, y el que más potencia instalada tiene. Sin embargo, la producción de energía eólica engloba una cadena de valor dividida en varias fases productivas. Por ello, tras haber analizado con detalle cada una de esas etapas y evaluar si tienen un impacto positivo o negativo sobre el tejido socioeconómico castellanoleonés, se ha llegado a la conclusión de que el sector eólico en Castilla y León ha tenido un impacto relativamente positivo. No obstante, es cierto que existen algunos elementos estructurales que limitan notoriamente ese efecto positivo. El sector eólico castellanoleonés es víctima de la deslocalización de actividades de alto contenido tecnológico hacia las comunidades autónomas de mayor renta. Además, por las características intrínsecas de muchas de las actividades vinculadas al sector, el empleo que se crea derivado de ellas es de naturaleza temporal; por lo que los efectos sobre el mercado de trabajo regional tienden a ser transitorios. En resumen, a pesar de liderar la producción de energía eólica y de aprovechar muchas de las ventajas que ofrece su cadena de valor, Castilla y León todavía puede atraer actividades que contribuyan a la revitalización económica, social y demográfica de la región

Efficient on-axis SLM engineering of optical vector modes

This work presents a method for the efficient experimental generation of arbitrary polarized vector beam modes. The optical system employs two liquid-crystal on silicon (LCOS) spatial light modulators (SLM) in a common path architecture, avoiding the use of beam-splitters. Each SLM displays a different phase-only mask, each one encoding a different pattern onto two orthogonal linear polarization components of the input beam. These phase-only masks are designed using a recently proposed random technique to encode complex amplitude values. This encoding technique reconstructs the complex function on-axis, thus avoiding incorporating carrier phases. By addressing such properly designed phase-only holograms we demonstrate arbitrary scalar modes on each polarization component, whose superposition results in a vector beam mode. Different superpositions of Laguerre–Gaussian and Hermite–Gaussian modes are obtained and the generated vector beam modes are analyzed. Moreover, the addition of a phase-bias proves itself useful to perform a phase-shifting technique in order to evaluate the correct phase of the generated vector beam

A General Purpose Configurable Navigation Controller for Micro Aerial Multirotor Vehicles

In this paper, we consider the problem of autonomous navigation of multirotor platforms in GPS-denied environments. The focus of this work is on safe navigation based on unperfect odometry measurements, such as on-board optical flow measurements. The multirotor platform is modeled as a flying object with specific kinematic constraints that must be taken into account in order to obtain successful results. A navigation controller is proposed featuring a set of configurable parameters that allow, for instance, to have a configuration setup for fast trajectory following, and another to soften the control laws and make the vehicle navigation more precise and slow whenever necessary. The proposed controller has been successfully implemented in two different multirotor platforms with similar sensoring capabilities showing the openness and tolerance of the approach. This research is focused around the Computer Vision Group's objective of applying multirotor vehicles to civilian service applications. The presented work was implemented to compete in the International Micro Air Vehicle Conference and Flight Competition IMAV 2012, gaining two awards: the Special Award on "Best Automatic Performance - IMAV 2012" and the second overall prize in the participating category "Indoor Flight Dynamics - Rotary Wing MAV". Most of the code related to the present work is available as two open-source projects hosted in GitHub

Design and implementation of a cloud-based platform for unleashing the personal and communal Internet of Things

Internet of Things (IoT) concept has attracted a lot of attention in recent years and it is foreseen as one of the technologies that will leverage the Future Internet. It is seen as a major enabler of novel applications and services that will foster efficiency and will ease every day´s life. However, current IoT solutions are mainly focusing on the development of centralized solutions that do not promote the democratization of the IoT but rather concentrate the IoT around a set of cloud-based platforms which pretend to be open but limit the capacity of the people to tailor their Personal and Communal IoT. This paper describes a software platform based on available generic enablers as defined by the FIWARE initiative. It extends the existing architecture models to accommodate the requirements stemming from the vision of people-sourced IoT devices which are shared to create applications and services in smart communities where the owners of the shared devices are always empowered to control who, and in which circumstances, has access to the shared information.This work has been partially funded by the research project SOCIOTAL, under FP7-ICT-2013.1.4 (ref. 609112) of the 7th Framework Programme of the European Community. This work has been also supported by the Spanish Government (Ministerio de Economía y Competitividad, Fondo Europeo de Desarrollo Regional, FEDER) by means of the project ADVICE “Dynamic Provisioning of Connectivity in High Density 5G Wireless Scenarios” (TEC2015-71329-C2-1-R)