901 resultados para Distributed Traffic Control
Resumo:
Previous research studies and operational trials have shown that using the airborne Required Time of Arrival (RTA) function, an aircraft can individually achieve an assigned time to a metering or merge point accurately. This study goes a step further and investigates the application of RTA to a real sequence of arriving aircraft into Melbourne Australia. Assuming that the actual arrival times were Controlled Time of Arrivals (CTAs) assigned to each aircraft, the study examines if the airborne RTA solution would work. Three scenarios were compared: a baseline scenario being the actual flown trajectories in a two hour time-span into Melbourne, a scenario in which the sequential landing slot times of the baseline scenario were assigned as CTAs and a third scenario in which the landing slots could be freely redistributed to the inbound traffic as CTAs. The research found that pressure on the terminal area would sometimes require aircraft to lose more time than possible through the RTA capability. Using linear holding as an additional measure to absorb extensive delays, up to 500NM (5%) of total track reduction and 1300kg (3%) of total fuel consumption could be saved in the scenario with landing slots freely distributed as CTAs, compared to the baseline scenario. Assigning CTAs in an arrival sequence requires the ground system to have an accurate trajectory predictor to propose additional delay measures (path stretching, linear holding) if necessary. Reducing the achievable time window of the aircraft to add control margin to the RTA function, had a negative impact and increased the amount of intervention other than speed control required to solve the sequence. It was concluded that the RTA capability is not a complete solution but merely a tool to assist in managing the increasing complexity of air traffic.
Resumo:
In this paper an on line self-tuned PID controller is proposed for the control of a car whose goal is to follow another one, at distances and speeds typical in urban traffic. The bestknown tuning mechanism is perhaps the MIT rule, due to its ease of implementation. However, as it is well known, this method does not guarantee the stability of the system, providing good results only for constant or slowly varying reference signals and in the absence of noise, which are unrealistic conditions. When the reference input varies with an appreciable rate or in presence of noise, eventually it could result in system instability. In this paper an alternative method is proposed that significantly improves the robustness of the system for varying inputs or in the presence of noise, as demonstrated by simulation.
Resumo:
In coffee processing the fermentation stage is considered one of the critical operations by its impact on the final quality of the product. However, the level of control of the fermentation process on each farm is often not adequate; the use of sensorics for controlling coffee fermentation is not common. The objective of this work is to characterize the fermentation temperature in a fermentation tank by applying spatial interpolation and a new methodology of data analysis based on phase space diagrams of temperature data, collected by means of multi-distributed, low cost and autonomous wireless sensors. A real coffee fermentation was supervised in the Cauca region (Colombia) with a network of 24 semi-passive TurboTag RFID temperature loggers with vacuum plastic cover, submerged directly in the fermenting mass. Temporal evolution and spatial distribution of temperature is described in terms of the phase diagram areas which characterizes the cyclic behaviour of temperature and highlights the significant heterogeneity of thermal conditions at different locations in the tank where the average temperature of the fermentation was 21.2 °C, although there were temperature ranges of 4.6°C, and average spatial standard deviation of ±1.21ºC. In the upper part of the tank we found high heterogeneity of temperatures, the higher temperatures and therefore the higher fermentation rates. While at the bottom, it has been computed an area in the phase diagram practically half of the area occupied by the sensors of the upper tank, therefore this location showed higher temperature homogeneity
Resumo:
Debido a la creciente relevancia de la computación en la nube y de los sistemas distribuidos, cobran también creciente interés las herramientas que ayudan a los desarrolladores y administradores a desempeñar sus funciones con la mayor eficacia posible. Por ello el objetivo principal de este trabajo es el desarrollo de una herramienta capaz de crear y controlar un entorno de almacenamiento de claves distribuidas desde una máquina local e independiente, aumentando la productividad mediante la automatización de todas las tareas. La herramienta desarrollada tiene la capacidad necesaria para integrarse tanto en proyectos que se encuentren en marcha como para proyectos que aún no hayan comenzado y proveer una solución sencilla, eficaz, y, sobre todo, útil. A lo largo del trabajo se ha realizado una gran tarea de análisis para determinar cuáles serán, de entre las posibilidades existentes, las más apropiadas para su implementación, teniendo en cuenta las tecnologías líderes disponibles en el estado del arte. Ello ha requerido también la obtención de una mejor comprensión de su funcionamiento interno. Se han realizado diferentes diseños que se han analizado y discutido en detalle para encontrar la solución que mejor se adaptaba a los objetivos propuestos. Y finalmente se ha desarrollado una herramienta ligera y sencilla, pero con un gran potencial para la administración. ---ABSTRACT---Due to the growing relevance of cloud computing and distributed systems it seems interesting to take into account the importance of the administration tools that help developers and administrators fulfill their duties in the most efficient ways. Because of this motivation, the main objective of this project is the development of a tool capable of creating and controlling a distributed key storing environment from a local and independent machine, improving the productivity thanks to the automation of all the involved tasks. The developed tool is able to integrate itself into already running projects as well as in not-yet-started ones, providing a simple, efficient and overall useful solution. During this project big tasks of research and analysis have taken place in order to determine, from the existent possibilities, the most suitable for its implementation, taking into account the leading technologies in the sector, which are described in the state of the art section. This has required the acquisition of a better insight of their inner workings. Some different designs have been made and have been discussed in detail with the intention of finding the solution that best suits the proposed objectives. And finally a lightweight and simple tool has been developed, which presents a very big potential for administration tasks.
Resumo:
Esta Tesis aborda los problemas de eficiencia de las redes eléctrica desde el punto de vista del consumo. En particular, dicha eficiencia es mejorada mediante el suavizado de la curva de consumo agregado. Este objetivo de suavizado de consumo implica dos grandes mejoras en el uso de las redes eléctricas: i) a corto plazo, un mejor uso de la infraestructura existente y ii) a largo plazo, la reducción de la infraestructura necesaria para suplir las mismas necesidades energéticas. Además, esta Tesis se enfrenta a un nuevo paradigma energético, donde la presencia de generación distribuida está muy extendida en las redes eléctricas, en particular, la generación fotovoltaica (FV). Este tipo de fuente energética afecta al funcionamiento de la red, incrementando su variabilidad. Esto implica que altas tasas de penetración de electricidad de origen fotovoltaico es perjudicial para la estabilidad de la red eléctrica. Esta Tesis trata de suavizar la curva de consumo agregado considerando esta fuente energética. Por lo tanto, no sólo se mejora la eficiencia de la red eléctrica, sino que también puede ser aumentada la penetración de electricidad de origen fotovoltaico en la red. Esta propuesta conlleva grandes beneficios en los campos económicos, social y ambiental. Las acciones que influyen en el modo en que los consumidores hacen uso de la electricidad con el objetivo producir un ahorro energético o un aumento de eficiencia son llamadas Gestión de la Demanda Eléctrica (GDE). Esta Tesis propone dos algoritmos de GDE diferentes para cumplir con el objetivo de suavizado de la curva de consumo agregado. La diferencia entre ambos algoritmos de GDE reside en el marco en el cual estos tienen lugar: el marco local y el marco de red. Dependiendo de este marco de GDE, el objetivo energético y la forma en la que se alcanza este objetivo son diferentes. En el marco local, el algoritmo de GDE sólo usa información local. Este no tiene en cuenta a otros consumidores o a la curva de consumo agregado de la red eléctrica. Aunque esta afirmación pueda diferir de la definición general de GDE, esta vuelve a tomar sentido en instalaciones locales equipadas con Recursos Energéticos Distribuidos (REDs). En este caso, la GDE está enfocada en la maximización del uso de la energía local, reduciéndose la dependencia con la red. El algoritmo de GDE propuesto mejora significativamente el auto-consumo del generador FV local. Experimentos simulados y reales muestran que el auto-consumo es una importante estrategia de gestión energética, reduciendo el transporte de electricidad y alentando al usuario a controlar su comportamiento energético. Sin embargo, a pesar de todas las ventajas del aumento de auto-consumo, éstas no contribuyen al suavizado del consumo agregado. Se han estudiado los efectos de las instalaciones locales en la red eléctrica cuando el algoritmo de GDE está enfocado en el aumento del auto-consumo. Este enfoque puede tener efectos no deseados, incrementando la variabilidad en el consumo agregado en vez de reducirlo. Este efecto se produce porque el algoritmo de GDE sólo considera variables locales en el marco local. Los resultados sugieren que se requiere una coordinación entre las instalaciones. A través de esta coordinación, el consumo debe ser modificado teniendo en cuenta otros elementos de la red y buscando el suavizado del consumo agregado. En el marco de la red, el algoritmo de GDE tiene en cuenta tanto información local como de la red eléctrica. En esta Tesis se ha desarrollado un algoritmo autoorganizado para controlar el consumo de la red eléctrica de manera distribuida. El objetivo de este algoritmo es el suavizado del consumo agregado, como en las implementaciones clásicas de GDE. El enfoque distribuido significa que la GDE se realiza desde el lado de los consumidores sin seguir órdenes directas emitidas por una entidad central. Por lo tanto, esta Tesis propone una estructura de gestión paralela en lugar de una jerárquica como en las redes eléctricas clásicas. Esto implica que se requiere un mecanismo de coordinación entre instalaciones. Esta Tesis pretende minimizar la cantidad de información necesaria para esta coordinación. Para lograr este objetivo, se han utilizado dos técnicas de coordinación colectiva: osciladores acoplados e inteligencia de enjambre. La combinación de estas técnicas para llevar a cabo la coordinación de un sistema con las características de la red eléctrica es en sí mismo un enfoque novedoso. Por lo tanto, este objetivo de coordinación no es sólo una contribución en el campo de la gestión energética, sino también en el campo de los sistemas colectivos. Los resultados muestran que el algoritmo de GDE propuesto reduce la diferencia entre máximos y mínimos de la red eléctrica en proporción a la cantidad de energía controlada por el algoritmo. Por lo tanto, conforme mayor es la cantidad de energía controlada por el algoritmo, mayor es la mejora de eficiencia en la red eléctrica. Además de las ventajas resultantes del suavizado del consumo agregado, otras ventajas surgen de la solución distribuida seguida en esta Tesis. Estas ventajas se resumen en las siguientes características del algoritmo de GDE propuesto: • Robustez: en un sistema centralizado, un fallo o rotura del nodo central provoca un mal funcionamiento de todo el sistema. La gestión de una red desde un punto de vista distribuido implica que no existe un nodo de control central. Un fallo en cualquier instalación no afecta el funcionamiento global de la red. • Privacidad de datos: el uso de una topología distribuida causa de que no hay un nodo central con información sensible de todos los consumidores. Esta Tesis va más allá y el algoritmo propuesto de GDE no utiliza información específica acerca de los comportamientos de los consumidores, siendo la coordinación entre las instalaciones completamente anónimos. • Escalabilidad: el algoritmo propuesto de GDE opera con cualquier número de instalaciones. Esto implica que se permite la incorporación de nuevas instalaciones sin afectar a su funcionamiento. • Bajo coste: el algoritmo de GDE propuesto se adapta a las redes actuales sin requisitos topológicos. Además, todas las instalaciones calculan su propia gestión con un bajo requerimiento computacional. Por lo tanto, no se requiere un nodo central con un alto poder de cómputo. • Rápido despliegue: las características de escalabilidad y bajo coste de los algoritmos de GDE propuestos permiten una implementación rápida. No se requiere una planificación compleja para el despliegue de este sistema. ABSTRACT This Thesis addresses the efficiency problems of the electrical grids from the consumption point of view. In particular, such efficiency is improved by means of the aggregated consumption smoothing. This objective of consumption smoothing entails two major improvements in the use of electrical grids: i) in the short term, a better use of the existing infrastructure and ii) in long term, the reduction of the required infrastructure to supply the same energy needs. In addition, this Thesis faces a new energy paradigm, where the presence of distributed generation is widespread over the electrical grids, in particular, the Photovoltaic (PV) generation. This kind of energy source affects to the operation of the grid by increasing its variability. This implies that a high penetration rate of photovoltaic electricity is pernicious for the electrical grid stability. This Thesis seeks to smooth the aggregated consumption considering this energy source. Therefore, not only the efficiency of the electrical grid is improved, but also the penetration of photovoltaic electricity into the grid can be increased. This proposal brings great benefits in the economic, social and environmental fields. The actions that influence the way that consumers use electricity in order to achieve energy savings or higher efficiency in energy use are called Demand-Side Management (DSM). This Thesis proposes two different DSM algorithms to meet the aggregated consumption smoothing objective. The difference between both DSM algorithms lie in the framework in which they take place: the local framework and the grid framework. Depending on the DSM framework, the energy goal and the procedure to reach this goal are different. In the local framework, the DSM algorithm only uses local information. It does not take into account other consumers or the aggregated consumption of the electrical grid. Although this statement may differ from the general definition of DSM, it makes sense in local facilities equipped with Distributed Energy Resources (DERs). In this case, the DSM is focused on the maximization of the local energy use, reducing the grid dependence. The proposed DSM algorithm significantly improves the self-consumption of the local PV generator. Simulated and real experiments show that self-consumption serves as an important energy management strategy, reducing the electricity transport and encouraging the user to control his energy behavior. However, despite all the advantages of the self-consumption increase, they do not contribute to the smooth of the aggregated consumption. The effects of the local facilities on the electrical grid are studied when the DSM algorithm is focused on self-consumption maximization. This approach may have undesirable effects, increasing the variability in the aggregated consumption instead of reducing it. This effect occurs because the algorithm only considers local variables in the local framework. The results suggest that coordination between these facilities is required. Through this coordination, the consumption should be modified by taking into account other elements of the grid and seeking for an aggregated consumption smoothing. In the grid framework, the DSM algorithm takes into account both local and grid information. This Thesis develops a self-organized algorithm to manage the consumption of an electrical grid in a distributed way. The goal of this algorithm is the aggregated consumption smoothing, as the classical DSM implementations. The distributed approach means that the DSM is performed from the consumers side without following direct commands issued by a central entity. Therefore, this Thesis proposes a parallel management structure rather than a hierarchical one as in the classical electrical grids. This implies that a coordination mechanism between facilities is required. This Thesis seeks for minimizing the amount of information necessary for this coordination. To achieve this objective, two collective coordination techniques have been used: coupled oscillators and swarm intelligence. The combination of these techniques to perform the coordination of a system with the characteristics of the electric grid is itself a novel approach. Therefore, this coordination objective is not only a contribution in the energy management field, but in the collective systems too. Results show that the proposed DSM algorithm reduces the difference between the maximums and minimums of the electrical grid proportionally to the amount of energy controlled by the system. Thus, the greater the amount of energy controlled by the algorithm, the greater the improvement of the efficiency of the electrical grid. In addition to the advantages resulting from the smoothing of the aggregated consumption, other advantages arise from the distributed approach followed in this Thesis. These advantages are summarized in the following features of the proposed DSM algorithm: • Robustness: in a centralized system, a failure or breakage of the central node causes a malfunction of the whole system. The management of a grid from a distributed point of view implies that there is not a central control node. A failure in any facility does not affect the overall operation of the grid. • Data privacy: the use of a distributed topology causes that there is not a central node with sensitive information of all consumers. This Thesis goes a step further and the proposed DSM algorithm does not use specific information about the consumer behaviors, being the coordination between facilities completely anonymous. • Scalability: the proposed DSM algorithm operates with any number of facilities. This implies that it allows the incorporation of new facilities without affecting its operation. • Low cost: the proposed DSM algorithm adapts to the current grids without any topological requirements. In addition, every facility calculates its own management with low computational requirements. Thus, a central computational node with a high computational power is not required. • Quick deployment: the scalability and low cost features of the proposed DSM algorithms allow a quick deployment. A complex schedule of the deployment of this system is not required.
Resumo:
Current worldwide building legislation requirements aim to the design and construction of technical services that reduce energy consumption and improve indoor hygrothermal conditions. The retail sector in Spain, with a lot of outdated technical systems, demands energy conservation measures in order to reduce the increasingly electrical consumption for cooling. Climatic separation with modern air curtains and advanced hygrothermal control systems enables energy savings and can keep suitable indoor air temperature and humidity of stores with intense pedestrian traffic, especially when located in hot humid climates. As stated in the article, the energy savings in commercial buildings with these systems exceeds 30%
Resumo:
Las aplicaciones distribuidas que precisan de un servicio multipunto fiable son muy numerosas, y entre otras es posible citar las siguientes: bases de datos distribuidas, sistemas operativos distribuidos, sistemas de simulación interactiva distribuida y aplicaciones de distribución de software, publicaciones o noticias. Aunque en sus orígenes el dominio de aplicación de tales sistemas distribuidos estaba reducido a una única subred (por ejemplo una Red de Área Local) posteriormente ha surgido la necesidad de ampliar su aplicabilidad a interredes. La aproximación tradicional al problema del multipunto fiable en interredes se ha basado principalmente en los dos siguientes puntos: (1) proporcionar en un mismo protocolo muchas garantías de servicio (por ejemplo fiabilidad, atomicidad y ordenación) y a su vez algunas de éstas en distintos grados, sin tener en cuenta que muchas aplicaciones multipunto que precisan fiabilidad no necesitan otras garantías; y (2) extender al entorno multipunto las soluciones ya adoptadas en el entorno punto a punto sin considerar las características diferenciadoras; y de aquí, que se haya tratado de resolver el problema de la fiabilidad multipunto con protocolos extremo a extremo (protocolos de transporte) y utilizando esquemas de recuperación de errores, centralizados (las retransmisiones se hacen desde un único punto, normalmente la fuente) y globales (los paquetes solicitados se vuelven a enviar al grupo completo). En general, estos planteamientos han dado como resultado protocolos que son ineficientes en tiempo de ejecución, tienen problemas de escalabilidad, no hacen un uso óptimo de los recursos de red y no son adecuados para aplicaciones sensibles al retardo. En esta Tesis se investiga el problema de la fiabilidad multipunto en interredes operando en modo datagrama y se presenta una forma novedosa de enfocar el problema: es más óptimo resolver el problema de la fiabilidad multipunto a nivel de red y separar la fiabilidad de otras garantías de servicio, que pueden ser proporcionadas por un protocolo de nivel superior o por la propia aplicación. Siguiendo este nuevo enfoque se ha diseñado un protocolo multipunto fiable que opera a nivel de red (denominado RMNP). Las características más representativas del RMNP son las siguientes; (1) sigue una aproximación orientada al emisor, lo cual permite lograr un grado muy alto de fiabilidad; (2) plantea un esquema de recuperación de errores distribuido (las retransmisiones se hacen desde ciertos encaminadores intermedios que siempre estarán más cercanos a los miembros que la propia fuente) y de ámbito restringido (el alcance de las retransmisiones está restringido a un cierto número de miembros). Este esquema hace posible optimizar el retardo medio de distribución y disminuir la sobrecarga introducida por las retransmisiones; (3) incorpora en ciertos encaminadores funciones de agregación y filtrado de paquetes de control, que evitan problemas de implosión y reducen el tráfico que fluye hacia la fuente. Con el fin de evaluar el comportamiento del protocolo diseñado, se han realizado pruebas de simulación obteniéndose como principales conclusiones que, el RMNP escala correctamente con el tamaño del grupo, hace un uso óptimo de los recursos de red y es adecuado para aplicaciones sensibles al retardo.---ABSTRACT---There are many distributed applications that require a reliable multicast service, including: distributed databases, distributed operating systems, distributed interactive simulation systems and distribution applications of software, publications or news. Although the application domain of distributed systems of this type was originally confíned to a single subnetwork (for example, a Local Área Network), it later became necessary extend their applicability to internetworks. The traditional approach to the reliable multicast problem in internetworks is based mainly on the following two points: (1) provide a lot of service guarantees in one and the same protocol (for example, reliability, atomicity and ordering) and different levéis of guarantee in some cases, without taking into account that many multicast applications that require reliability do not need other guarantees, and (2) extend solutions adopted in the unicast environment to the multicast environment without taking into account their distinctive characteristics. So, the attempted solutions to the multicast reliability problem were end-to-end protocols (transport protocols) and centralized error recovery schemata (retransmissions made from a single point, normally the source) and global error retrieval schemata (the requested packets are retransmitted to the whole group). Generally, these approaches have resulted in protocols that are inefficient in execution time, have scaling problems, do not make optimum use of network resources and are not suitable for delay-sensitive applications. Here, the multicast reliability problem is investigated in internetworks operating in datagram mode and a new way of approaching the problem is presented: it is better to solve to the multicast reliability problem at network level and sepárate reliability from other service guarantees that can be supplied by a higher protocol or the application itself. A reliable multicast protocol that operates at network level (called RMNP) has been designed on the basis of this new approach. The most representative characteristics of the RMNP are as follows: (1) it takes a transmitter-oriented approach, which provides for a very high reliability level; (2) it provides for an error retrieval schema that is distributed (the retransmissions are made from given intermedíate routers that will always be closer to the members than the source itself) and of restricted scope (the scope of the retransmissions is confined to a given number of members), and this schema makes it possible to optimize the mean distribution delay and reduce the overload caused by retransmissions; (3) some routers include control packet aggregation and filtering functions that prevent implosión problems and reduce the traffic flowing towards the source. Simulation test have been performed in order to evalúate the behaviour of the protocol designed. The main conclusions are that the RMNP scales correctly with group size, makes optimum use of network resources and is suitable for delay-sensitive applications.
Resumo:
In this work we review some earlier distributed algorithms developed by the authors and collaborators, which are based on two different approaches, namely, distributed moment estimation and distributed stochastic approximations. We show applications of these algorithms on image compression, linear classification and stochastic optimal control. In all cases, the benefit of cooperation is clear: even when the nodes have access to small portions of the data, by exchanging their estimates, they achieve the same performance as that of a centralized architecture, which would gather all the data from all the nodes.
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The study of the temperature gradients in cold stores and containers is a critical issue in the food industry for the quality assurance of products during transport and for minimising losses. This work presents an analysis of the temperatures during the refrigerated transport of 4,320 kg of blueberries in a reefer (set point temperature at ?1ºC) on a container ship from Montevideo (Uruguay) to Verona (Italy). The monitoring was performed by using semi-passive RFID loggers (TurboTag cards). The objective was to carry out a multi-distributed supervision using low-cost, wireless and autonomous sensors for the characterisation of the distribution and spatial gradients of temperatures during a long distance transport. Data analysis shows spatial (phase space) and temporal sequencing diagrams and reveals a significant heterogeneity of temperature at different locations in the container, which highlights the ineffectiveness of a temperature control system based on a single sensor, as is usually done.
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La presente Tesis está orientada al análisis de la supervisión multidistribuida de tres procesos agroalimentarios: el secado solar, el transporte refrigerado y la fermentación de café, a través de la información obtenida de diferentes dispositivos de adquisición de datos, que incorporan sensores, así como el desarrollo de metodologías de análisis de series temporales, modelos y herramientas de control de procesos para la ayuda a la toma de decisiones en las operaciones de estos entornos. En esta tesis se han utilizado: tarjetas RFID (TemTrip®) con sistema de comunicación por radiofrecuencia y sensor de temperatura; el registrador (i-Button®), con sensor integrado de temperatura y humedad relativa y un tercer prototipo empresarial, módulo de comunicación inalámbrico Nlaza, que integra un sensor de temperatura y humedad relativa Sensirion®. Estos dispositivos se han empleado en la conformación de redes multidistribuidas de sensores para la supervisión de: A) Transportes de producto hortofrutícola realizados en condiciones comerciales reales, que son: dos transportes terrestre de producto de IV gama desde Murcia a Madrid; transporte multimodal (barco-barco) de limones desde Montevideo (Uruguay) a Cartagena (España) y transporte multimodal (barco-camión) desde Montevideo (Uruguay) a Verona (Italia). B) dos fermentaciones de café realizadas en Popayán (Colombia) en un beneficiadero. Estas redes han permitido registrar la dinámica espacio-temporal de temperaturas y humedad relativa de los procesos estudiados. En estos procesos de transporte refrigerado y fermentación la aplicación de herramientas de visualización de datos y análisis de conglomerados, han permitido identificar grupos de sensores que presentan patrones análogos de sus series temporales, caracterizando así zonas con dinámicas similares y significativamente diferentes del resto y permitiendo definir redes de sensores de menor densidad cubriendo las diferentes zonas identificadas. Las metodologías de análisis complejo de las series espacio-temporales (modelos psicrométricos, espacio de fases bidimensional e interpolaciones espaciales) permitieron la cuantificación de la variabilidad del proceso supervisado tanto desde el punto de vista dinámico como espacial así como la identificación de eventos. Constituyendo así herramientas adicionales de ayuda a la toma de decisiones en el control de los procesos. Siendo especialmente novedosa la aplicación de la representación bidimensional de los espacios de fases en el estudio de las series espacio-temporales de variables ambientales en aplicaciones agroalimentarias, aproximación que no se había realizado hasta el momento. En esta tesis también se ha querido mostrar el potencial de un sistema de control basado en el conocimiento experto como es el sistema de lógica difusa. Se han desarrollado en primer lugar, los modelos de estimación del contenido en humedad y las reglas semánticas que dirigen el proceso de control, el mejor modelo se ha seleccionado mediante un ensayo de secado realizado sobre bolas de hidrogel como modelo alimentario y finalmente el modelo se ha validado mediante un ensayo en el que se deshidrataban láminas de zanahoria. Los resultados sugirieron que el sistema de control desarrollado, es capaz de hacer frente a dificultades como las variaciones de temperatura día y noche, consiguiendo un producto con buenas características de calidad comparables a las conseguidas sin aplicar ningún control sobre la operación y disminuyendo así el consumo energético en un 98% con respecto al mismo proceso sin control. La instrumentación y las metodologías de análisis de datos implementadas en esta Tesis se han mostrado suficientemente versátiles y transversales para ser aplicadas a diversos procesos agroalimentarios en los que la temperatura y la humedad relativa sean criterios de control en dichos procesos, teniendo una aplicabilidad directa en el sector industrial ABSTRACT This thesis is focused on the analysis of multi-distributed supervision of three agri-food processes: solar drying, refrigerated transport and coffee fermentation, through the information obtained from different data acquisition devices with incorporated sensors, as well as the development of methodologies for analyzing temporary series, models and tools to control processes in order to help in the decision making in the operations within these environments. For this thesis the following has been used: RFID tags (TemTrip®) with a Radiofrequency ID communication system and a temperature sensor; the recorder (i-Button®), with an integrated temperature and relative humidity and a third corporate prototype, a wireless communication module Nlaza, which has an integrated temperature and relative humidity sensor, Sensirion®. These devices have been used in creating three multi-distributed networks of sensors for monitoring: A) Transport of fruits and vegetables made in real commercial conditions, which are: two land trips of IV range products from Murcia to Madrid; multimodal transport (ship - ship) of lemons from Montevideo (Uruguay) to Cartagena (Spain) and multimodal transport (ship - truck) from Montevideo (Uruguay) to Verona (Italy). B) Two coffee fermentations made in Popayan (Colombia) in a coffee processing plant. These networks have allowed recording the time space dynamics of temperatures and relative humidity of the processed under study. Within these refrigerated transport and fermentation processes, the application of data display and cluster analysis tools have allowed identifying sensor groups showing analogical patterns of their temporary series; thus, featuring areas with similar and significantly different dynamics from the others and enabling the definition of lower density sensor networks covering the different identified areas. The complex analysis methodologies of the time space series (psychrometric models, bi-dimensional phase space and spatial interpolation) allowed quantifying the process variability of the supervised process both from the dynamic and spatial points of view; as well as the identification of events. Thus, building additional tools to aid decision-making on process control brought the innovative application of the bi-dimensional representation of phase spaces in the study of time-space series of environmental variables in agri-food applications, an approach that had not been taken before. This thesis also wanted to show the potential of a control system based on specialized knowledge such as the fuzzy logic system. Firstly, moisture content estimation models and semantic rules directing the control process have been developed, the best model has been selected by an drying assay performed on hydrogel beads as food model; and finally the model has been validated through an assay in which carrot sheets were dehydrated. The results suggested that the control system developed is able to cope with difficulties such as changes in temperature daytime and nighttime, getting a product with good quality features comparable to those features achieved without applying any control over the operation and thus decreasing consumption energy by 98% compared to the same uncontrolled process. Instrumentation and data analysis methodologies implemented in this thesis have proved sufficiently versatile and cross-cutting to apply to several agri-food processes in which the temperature and relative humidity are the control criteria in those processes, having a direct effect on the industry sector.
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Acknowledgements We are grateful to THERAmetrics for the study management, data collection and analysis. The authors would like to thank the following investigators for their contribution (>30 patients enrolled): F. Fohler, A.G. Haider, J. Hesse-Tonsa, J. Messner, W. Pohl (Austria); G. Joos, J.L. Halloy, R. Peche, H. Simonis, P. Van den Brande (Belgium); B. Bugnas, J.M. Chavaillon, P. Debove, S. Dury, L. Mathieu, O. Lagrange, A. Prudhomme, S. Verdier (France); A. Benedix, O. Kestermann, A. Deimling, G. Eckhardt, M. Gernhold, V. Grimm-Sachs, M. Hoefer, G. Hoheisel, C. Stolpe, C. Schilder, M. John, J. Uerscheln, K.H. Zeisler (Germany); A. Chaniotou, P. Demertzis, V. Filaditaki-Loverdou, A. Gaga, E. Georgatou-Papageorgiou, S. Michailidis, G. Pavkalou, M. Toumpis (Greece); K. Csicsari, K. Hajdu, M. Póczi, M. Kukuly, T. Kecskes, C. Hangonyi, J. Schlezak, E. Takács, M. Szabo,G. Szabó, C. Szabo (Hungary); G.W. Canonica, W. Castellani, A. Cirillo, M.P. Foschino Barbaro, M. Gjomarkaj, G. Guerra, G. Idotta, D. Legnani, M. Lo Schiavo, R. Maselli, F. Mazza, S. Nutini, P. Paggiaro, A. Pietra, O. Resta, S. Salis, N.A. Scichilone, M.C. Zappa, A. Zedda (Italy); M. Goosens, R. Heller, K. Mansour, C. Meek, J. van den Berg (The Netherlands); A. Antczak, M. Faber, D. Madra-Rogacka, G. Mincewicz, M. Michnar, D. Olejniczak, G. Pulka, Z. Sankowski, K. Kowal, I. Krupa-Borek, B. Kubicka Kozik, K. Kuczynska, P. Kuna, A. Kwasniewski, M. Wozniak (Poland); F. Casas Maldonado, C. Cisneros, J. de Miguel Díez, L.M. Entrenas Costa, B. Garcìa-Cosio, M.V. Gonzales, L. Lores, M. Luengo, C. Martinez, C. Melero, I. Mir, X. Munoz, A. Pacheco, V. Plaza, J. Serra, J. Serrano, J.G. Soto Campos (Spain); T. Bekci, R. Demir, N. Dursunoglu, D. Ediger, A. Ekici, O. Goksel, H. Gunen, I.K. Oguzulgen, Z.F. Ozseker, (Turkey); L. Barnes, T. Hall, S. Montgomerie, J. Purohit, J. Ryan (United Kingdom). The authors would also like to thank P. Galletti (THERAMetrics S.p.A., Sesto San Giovanni, Italy) and K. Stockmeyer (THERAMetrics GmbH, Essen, Germany) for providing editorial assistance in the preparation of this manuscript. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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Acknowledgments This research was funded by NERC Grants NE/J01396X/1; NE/E006434/1 to XL. Y. M. was funded by a Marie Curie FP7-PEOPLE-2011-IEF 300288. We profusely thank the Scottish Mink Initiative, staff, funders and multiple mink volunteers for the continued effort, samples and enthusiasm. The Scottish Water Vole Conservation Project was funded by The Tubney Charitable trust, Scottish Natural Heritage, the Cairngorms National Park Authority and the People’s Trust for Endangered Species. We also thank the Associate Editor and two anonymous referees for their thoughtful reviews.
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To “control” a system is to make it behave (hopefully) according to our “wishes,” in a way compatible with safety and ethics, at the least possible cost. The systems considered here are distributed—i.e., governed (modeled) by partial differential equations (PDEs) of evolution. Our “wish” is to drive the system in a given time, by an adequate choice of the controls, from a given initial state to a final given state, which is the target. If this can be achieved (respectively, if we can reach any “neighborhood” of the target) the system, with the controls at our disposal, is exactly (respectively, approximately) controllable. A very general (and fuzzy) idea is that the more a system is “unstable” (chaotic, turbulent) the “simplest,” or the “cheapest,” it is to achieve exact or approximate controllability. When the PDEs are the Navier–Stokes equations, it leads to conjectures, which are presented and explained. Recent results, reported in this expository paper, essentially prove the conjectures in two space dimensions. In three space dimensions, a large number of new questions arise, some new results support (without proving) the conjectures, such as generic controllability and cases of decrease of cost of control when the instability increases. Short comments are made on models arising in climatology, thermoelasticity, non-Newtonian fluids, and molecular chemistry. The Introduction of the paper and the first part of all sections are not technical. Many open questions are mentioned in the text.
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Lipid rafts are microdomains present within membranes of most cell types. These membrane microdomains, which are enriched in cholesterol and glycosphingolipids, have been implicated in the regulation of certain signal transduction and membrane traffic pathways. To investigate the possibility that lipid rafts organize exocytotic pathways in neuroendocrine cells, we examined the association of proteins of the exocytotic machinery with rafts purified from PC12 cells. The target soluble N-ethylmaleimide-sensitive factor attachment protein receptor (tSNARE) proteins syntaxin 1A and synaptosomal-associated protein of 25 kDa (SNAP-25) were both found to be highly enriched in lipid rafts (≈25-fold). The vesicle SNARE vesicle-associated membrane protein (VAMP)2 was also present in raft fractions, but the extent of this recovery was variable. However, further analysis revealed that the majority of VAMP2 was associated with a distinct class of raft with different detergent solubility characteristics to the rafts containing syntaxin 1A and SNAP-25. Interestingly, no other studied secretory proteins were significantly associated with lipid rafts, including SNARE effector proteins such as nSec1. Chemical crosslinking experiments showed that syntaxin1A/SNAP-25 heterodimers were equally present in raft and nonraft fractions, whereas syntaxin1A/nSec1 complexes were detected only in nonraft fractions. SDS-resistance assays revealed that raft-associated syntaxin1A/SNAP-25 heterodimers were able to interact with VAMP2. Finally, reduction of cellular cholesterol levels decreased the extent of regulated exocytosis of dopamine from PC12 cells. The results described suggest that the interaction of SNARE proteins with lipid rafts is important for exocytosis and may allow structural and spatial organization of the secretory machinery.
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The critical role of tumor necrosis factor (TNF) as a mediator in autoimmune inflammatory processes is evident from in vivo studies with TNF-blocking agents. However, the mechanisms by which TNF, and possibly also its homologue lymphotoxin alpha, contributes to development of pathology in rheumatoid arthritis and Crohn disease and in animal models like experimental autoimmune encephalomyelitis is unclear. Possibilities include regulation of vascular adhesion molecules enabling leukocyte movement into tissues or direct cytokine-mediated effector functions such as mediation of tissue damage. Here we show that administration of a TNF receptor (55 kDa)-IgG fusion protein prevented clinical signs of actively induced experimental autoimmune encephalomyelitis. Significantly, the total number of CD4+ T lymphocytes isolated from the central nervous system of clinically healthy treated versus diseased control animals was comparable. By using a CD45 congenic model of passively transferred experimental autoimmune encephalomyelitis to enable tracking of myelin basic protein-specific effector T lymphocytes, prevention of clinical signs of disease was again demonstrated in treated animals but without quantitative or qualitative impediment to the movement of autoreactive T lymphocytes to and within the central nervous system. Thus, despite the uninterrupted movement of specific T lymphocytes into the target tissue, subsequent disease development was blocked. This provides compelling evidence for a direct effector role of TNF/lymphotoxin alpha in autoimmune tissue damage.