960 resultados para Collaborative P2P Systems


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This thesis presents the formal definition of a novel Mobile Cloud Computing (MCC) extension of the Networked Autonomic Machine (NAM) framework, a general-purpose conceptual tool which describes large-scale distributed autonomic systems. The introduction of autonomic policies in the MCC paradigm has proved to be an effective technique to increase the robustness and flexibility of MCC systems. In particular, autonomic policies based on continuous resource and connectivity monitoring help automate context-aware decisions for computation offloading. We have also provided NAM with a formalization in terms of a transformational operational semantics in order to fill the gap between its existing Java implementation NAM4J and its conceptual definition. Moreover, we have extended NAM4J by adding several components with the purpose of managing large scale autonomic distributed environments. In particular, the middleware allows for the implementation of peer-to-peer (P2P) networks of NAM nodes. Moreover, NAM mobility actions have been implemented to enable the migration of code, execution state and data. Within NAM4J, we have designed and developed a component, denoted as context bus, which is particularly useful in collaborative applications in that, if replicated on each peer, it instantiates a virtual shared channel allowing nodes to notify and get notified about context events. Regarding the autonomic policies management, we have provided NAM4J with a rule engine, whose purpose is to allow a system to autonomously determine when offloading is convenient. We have also provided NAM4J with trust and reputation management mechanisms to make the middleware suitable for applications in which such aspects are of great interest. To this purpose, we have designed and implemented a distributed framework, denoted as DARTSense, where no central server is required, as reputation values are stored and updated by participants in a subjective fashion. We have also investigated the literature regarding MCC systems. The analysis pointed out that all MCC models focus on mobile devices, and consider the Cloud as a system with unlimited resources. To contribute in filling this gap, we defined a modeling and simulation framework for the design and analysis of MCC systems, encompassing both their sides. We have also implemented a modular and reusable simulator of the model. We have applied the NAM principles to two different application scenarios. First, we have defined a hybrid P2P/cloud approach where components and protocols are autonomically configured according to specific target goals, such as cost-effectiveness, reliability and availability. Merging P2P and cloud paradigms brings together the advantages of both: high availability, provided by the Cloud presence, and low cost, by exploiting inexpensive peers resources. As an example, we have shown how the proposed approach can be used to design NAM-based collaborative storage systems based on an autonomic policy to decide how to distribute data chunks among peers and Cloud, according to cost minimization and data availability goals. As a second application, we have defined an autonomic architecture for decentralized urban participatory sensing (UPS) which bridges sensor networks and mobile systems to improve effectiveness and efficiency. The developed application allows users to retrieve and publish different types of sensed information by using the features provided by NAM4J's context bus. Trust and reputation is managed through the application of DARTSense mechanisms. Also, the application includes an autonomic policy that detects areas characterized by few contributors, and tries to recruit new providers by migrating code necessary to sensing, through NAM mobility actions.

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Part 20: Health and Care Networks

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This paper proposes an implementation, based on a multi-agent system, of a management system for automated negotiation of electricity allocation for charging electric vehicles (EVs) and simulates its performance. The widespread existence of charging infrastructures capable of autonomous operation is recognised as a major driver towards the mass adoption of EVs by mobility consumers. Eventually, conflicting requirements from both power grid and EV owners require automated middleman aggregator agents to intermediate all operations, for example, bidding and negotiation, between these parts. Multi-agent systems are designed to provide distributed, modular, coordinated and collaborative management systems; therefore, they seem suitable to address the management of such complex charging infrastructures. Our solution consists in the implementation of virtual agents to be integrated into the management software of a charging infrastructure. We start by modelling the multi-agent architecture using a federated, hierarchical layers setup and as well as the agents' behaviours and interactions. Each of these layers comprises several components, for example, data bases, decision-making and auction mechanisms. The implementation of multi-agent platform and auctions rules, and of models for battery dynamics, is also addressed. Four scenarios were predefined to assess the management system performance under real usage conditions, considering different types of profiles for EVs owners', different infrastructure configurations and usage and different loads on the utility grid (where real data from the concession holder of the Portuguese electricity transmission grid is used). Simulations carried with the four scenarios validate the performance of the modelled system while complying with all the requirements. Although all of these have been performed for one charging station alone, a multi-agent design may in the future be used for the higher level problem of distributing energy among charging stations. Copyright (c) 2014 John Wiley & Sons, Ltd.

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User generated content shared in online communities is often described using collaborative tagging systems where users assign labels to content resources. As a result, a folksonomy emerges that relates a number of tags with the resources they label and the users that have used them. In this paper we analyze the folksonomy of Freesound, an online audio clip sharing site which contains more than two million users and 150,000 user-contributed sound samplescovering a wide variety of sounds. By following methodologies taken from similar studies, we compute some metrics that characterize the folksonomy both at the globallevel and at the tag level. In this manner, we are able to betterunderstand the behavior of the folksonomy as a whole, and also obtain some indicators that can be used as metadata for describing tags themselves. We expect that such a methodology for characterizing folksonomies can be useful to support processes such as tag recommendation or automatic annotation of online resources.

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With the evolution of the P2P research eld, new problems, such as those related with information security, have arisen. It is important to provide security mechanisms to P2P systems, since it has already become one of the key issues when evaluating them. However, even though many P2P systems have been adapted to provide a security baseline to their underlying applications, more advanced capabilities are becoming necessary. Speci cally, privacy preservation and anonymity are deemed essential to make the information society sustainable. Unfortunately, sometimes, it may be di cult to attain anonymity unless it is included into the system's initial design. The JXTA open protocols speci cation is a good example of this kind of scenario. This work studies how to provide anonymity to JXTA's architecture in a feasible manner and proposes an extension which allows deployed services to process two-way messaging without disclosing the endpoints'identities to third parties.

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En l'actualitat, la maduresa del camp de la investigació P2P empès a través de nous problemes, relacionats amb la seguretat. Per aquesta raó, la seguretat comença a convertir-se en una de les qüestions clau en l'avaluació d'un sistema P2P, i és important proporcionar mecanismes de seguretat per a sistemes P2P. El projecte JXTAOverlay fa un esforç per utilitzar la tecnologia JXTA per proporcionar un conjunt genèric de funcions que poden ser utilitzades pels desenvolupadors per desplegar aplicacions P2P. No obstant això, encara que el seu disseny es va centrar en qüestions com ara l'escalabilitat o el rendiment general, no va tenir en compte la seguretat. Aquest treball proposa un marc de seguretat, adaptat específicament a la idiosincràsia del JXTAOverlay.

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Peer-to-Peer (P2P) technology has revolutionized file exchange activities besides enhancing processing power distribution. As such, this technology which is nowadays made freely available to all internet users also imposes a threat as it enables the illegal distribution of copyrighted digital work. P2P technology continuously evolves in a greater pace than copyright legislation, leading to compatibility gaps between the applicability of copyright law and the illicit file sharing and downloading. Such issues give high incentives to consumers to practise piracy using P2P systems with a low perception of risk towards prosecution, leading to substantial losses for copyright owners. This study focuses on developing insights for content owners on consumer behaviour towards piracy in Finland, where quantitative analyses are assessed using a data set based on a survey conducted by the Helsinki Institute for IT. The research approach investigates the significance of three fundamental areas in relation to evaluate consumer behaviour as: environmental-related factors, innovation-related factors and consumer-related. each of these are integrates concepts derived in previous theoretical models such as the technology acceptance model, theory of reasoned action, theory of planned behaviour, the issue-risk-judgement model and the Hunt & Vitell’s model.

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In Peer-to-Peer (P2P) networks, it is often desirable to assign node IDs which preserve locality relationships in the underlying topology. Node locality can be embedded into node IDs by utilizing a one dimensional mapping by a Hilbert space filling curve on a vector of network distances from each node to a subset of reference landmark nodes within the network. However this approach is fundamentally limited because while robustness and accuracy might be expected to improve with the number of landmarks, the effectiveness of 1 dimensional Hilbert Curve mapping falls for the curse of dimensionality. This work proposes an approach to solve this issue using Landmark Multidimensional Scaling (LMDS) to reduce a large set of landmarks to a smaller set of virtual landmarks. This smaller set of landmarks has been postulated to represent the intrinsic dimensionality of the network space and therefore a space filling curve applied to these virtual landmarks is expected to produce a better mapping of the node ID space. The proposed approach, the Virtual Landmarks Hilbert Curve (VLHC), is particularly suitable for decentralised systems like P2P networks. In the experimental simulations the effectiveness of the methods is measured by means of the locality preservation derived from node IDs in terms of latency to nearest neighbours. A variety of realistic network topologies are simulated and this work provides strong evidence to suggest that VLHC performs better than either Hilbert Curves or LMDS use independently of each other.

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Gossip (or Epidemic) protocols have emerged as a communication and computation paradigm for large-scale networked systems. These protocols are based on randomised communication, which provides probabilistic guarantees on convergence speed and accuracy. They also provide robustness, scalability, computational and communication efficiency and high stability under disruption. This work presents a novel Gossip protocol named Symmetric Push-Sum Protocol for the computation of global aggregates (e.g., average) in decentralised and asynchronous systems. The proposed approach combines the simplicity of the push-based approach and the efficiency of the push-pull schemes. The push-pull schemes cannot be directly employed in asynchronous systems as they require synchronous paired communication operations to guarantee their accuracy. Although push schemes guarantee accuracy even with asynchronous communication, they suffer from a slower and unstable convergence. Symmetric Push- Sum Protocol does not require synchronous communication and achieves a convergence speed similar to the push-pull schemes, while keeping the accuracy stability of the push scheme. In the experimental analysis, we focus on computing the global average as an important class of node aggregation problems. The results have confirmed that the proposed method inherits the advantages of both other schemes and outperforms well-known state of the art protocols for decentralized Gossip-based aggregation.

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Automated Production Systems Development involves aspects concerning the integration of technological components that exist on the market, such as: Programmable Logic Controllers (PLC), robot manipulators, various sensors and actuators, image processing systems, communication networks and collaborative supervisory systems; all integrated into a single application. This paper proposes an automated platform for experimentation, implemented through typical architecture for Automated Production Systems, which integrates the technological components described above, in order to allow researchers and students to carry out practical laboratory activities. These activities will complement the theoretical knowledge acquired by the students in the classroom, thus improving their training and professional skills. A platform designed using this generic structure will allow users to work within an educational environment that reflects most aspects found in Industrial Automated Manufacturing Systems, such as technology integration, communication networks, process control and production management. In addition, this platform offers the possibility complete automated process of control and supervision via remote connection through the internet (WebLab), enabling knowledge sharing between different teaching and research groups.

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The Peer-to-Peer network paradigm is drawing the attention of both final users and researchers for its features. P2P networks shift from the classic client-server approach to a high level of decentralization where there is no central control and all the nodes should be able not only to require services, but to provide them to other peers as well. While on one hand such high level of decentralization might lead to interesting properties like scalability and fault tolerance, on the other hand it implies many new problems to deal with. A key feature of many P2P systems is openness, meaning that everybody is potentially able to join a network with no need for subscription or payment systems. The combination of openness and lack of central control makes it feasible for a user to free-ride, that is to increase its own benefit by using services without allocating resources to satisfy other peers’ requests. One of the main goals when designing a P2P system is therefore to achieve cooperation between users. Given the nature of P2P systems based on simple local interactions of many peers having partial knowledge of the whole system, an interesting way to achieve desired properties on a system scale might consist in obtaining them as emergent properties of the many interactions occurring at local node level. Two methods are typically used to face the problem of cooperation in P2P networks: 1) engineering emergent properties when designing the protocol; 2) study the system as a game and apply Game Theory techniques, especially to find Nash Equilibria in the game and to reach them making the system stable against possible deviant behaviors. In this work we present an evolutionary framework to enforce cooperative behaviour in P2P networks that is alternative to both the methods mentioned above. Our approach is based on an evolutionary algorithm inspired by computational sociology and evolutionary game theory, consisting in having each peer periodically trying to copy another peer which is performing better. The proposed algorithms, called SLAC and SLACER, draw inspiration from tag systems originated in computational sociology, the main idea behind the algorithm consists in having low performance nodes copying high performance ones. The algorithm is run locally by every node and leads to an evolution of the network both from the topology and from the nodes’ strategy point of view. Initial tests with a simple Prisoners’ Dilemma application show how SLAC is able to bring the network to a state of high cooperation independently from the initial network conditions. Interesting results are obtained when studying the effect of cheating nodes on SLAC algorithm. In fact in some cases selfish nodes rationally exploiting the system for their own benefit can actually improve system performance from the cooperation formation point of view. The final step is to apply our results to more realistic scenarios. We put our efforts in studying and improving the BitTorrent protocol. BitTorrent was chosen not only for its popularity but because it has many points in common with SLAC and SLACER algorithms, ranging from the game theoretical inspiration (tit-for-tat-like mechanism) to the swarms topology. We discovered fairness, meant as ratio between uploaded and downloaded data, to be a weakness of the original BitTorrent protocol and we drew inspiration from the knowledge of cooperation formation and maintenance mechanism derived from the development and analysis of SLAC and SLACER, to improve fairness and tackle freeriding and cheating in BitTorrent. We produced an extension of BitTorrent called BitFair that has been evaluated through simulation and has shown the abilities of enforcing fairness and tackling free-riding and cheating nodes.

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El presente trabajo se basa en la filosofía de la Construcción sin Pérdidas (“Lean Construction”), analizando la situación de esta filosofía en el sector de la edificación en el contexto internacional y español, respondiendo las siguientes preguntas: 1. ¿Cómo surge el “Lean Construction”? 2. ¿Cuáles son sus actividades, funciones y cometidos? 3. ¿Existe regulación del ¨Lean Construction” en otros países? 4. ¿Existe demanda del ¨Lean Construction” en España? 5. ¿Existe regulación del ¨Lean Construction” en España? 6. ¿Cómo debería ser la regulación ¨Lean Construction” en España? 7. ¿Cuál es la relación del “Lean Construction” con el “Project & Construction Management”? 8. ¿Cómo debería ser la regulación de “Lean Construction” en España considerando su relación con el “Project & Construction Management”? Las preguntas indicadas las hemos respondido detalladamente en el presente trabajo, a continuación se resume las respuestas a dichas preguntas: 1. El “Lean Construction” surge en agosto de 1992, cuando el investigador finlandés Lauri Koskela publicó en la Universidad de Stanford el reporte TECHNICAL REPORT N° 72 titulado “Application of the New Production Philosophy to Construction”. Un año más tarde el Dr. Koskela invitó a un grupo de especialistas en construcción al primer workshop de esta materia en Finlandia, dando origen al International Group for Lean Construction (IGLC) lo que ha permitido extender la filosofía a EEUU, Europa, América, Asia, Oceanía y África. “Lean Construction” es un sistema basado en el enfoque “Lean Production” desarrollado en Japón por Toyota Motors a partir de los años cincuenta, sistema que permitió a sus fábricas producir unidades con mayor eficiencia que las industrias americanas, con menores recursos, en menor tiempo, y con un número menor de errores de fabricación. 2. El sistema “Lean Construction” busca maximizar el valor y disminuir las pérdidas de los proyectos generando una coordinación eficiente entre los involucrados, manejando un proyecto como un sistema de producción, estrechando la colaboración entre los participantes de los proyectos, capacitándoles y empoderándoles, fomentando una cultura de cambio. Su propósito es desarrollar un proceso de construcción en el que no hayan accidentes, ni daños a equipos, instalaciones, entorno y comunidad, que se realice en conformidad con los requerimientos contractuales, sin defectos, en el plazo requerido, respetando los costes presupuestados y con un claro enfoque en la eliminación o reducción de las pérdidas, es decir, las actividades que no generen beneficios. El “Last Planner System”, o “Sistema del Último Planificador”, es un sistema del “Lean Construction” que por su propia naturaleza protege a la planificación y, por ende, ayuda a maximizar el valor y minimizar las pérdidas, optimizando de manera sustancial los sistemas de seguridad y salud. El “Lean Construction” se inició como un concepto enfocado a la ejecución de las obras, posteriormente se aplicó la filosofía a todas las etapas del proyecto. Actualmente considera el desarrollo total de un proyecto, desde que nace la idea hasta la culminación de la obra y puesta en marcha, considerando el ciclo de vida completo del proyecto. Es una filosofía de gestión, metodologías de trabajo y una cultura empresarial orientada a la eficiencia de los procesos y flujos. La filosofía “Lean Construction” se está expandiendo en todo el mundo, además está creciendo en su alcance, influyendo en la gestión contractual de los proyectos. Su primera evolución consistió en la creación del sistema “Lean Project Delivery System”, que es el concepto global de desarrollo de proyectos. Posteriormente, se proponen el “Target Value Design”, que consiste en diseñar de forma colaborativa para alcanzar los costes y el valor requerido, y el “Integrated Project Delivery”, en relación con sistemas de contratos relacionales (colaborativos) integrados, distintos a los contratos convencionales. 3. Se verificó que no existe regulación específica del ¨Lean Construction” en otros países, en otras palabras, no existe el agente con el nombre específico de “Especialista en Lean Construction” o similar, en consecuencia, es un agente adicional en el proyecto de la edificación, cuyas funciones y cometidos se pueden solapar con los del “Project Manager”, “Construction Manager”, “Contract Manager”, “Safety Manager”, entre otros. Sin embargo, se comprobó la existencia de formatos privados de contratos colaborativos de Integrated Project Delivery, los cuales podrían ser tomados como unas primeras referencias para futuras regulaciones. 4. Se verificó que sí existe demanda del ¨Lean Construction” en el desarrollo del presente trabajo, aunque aún su uso es incipiente, cada día existe más interesados en el tema. 5. No existe regulación del ¨Lean Construction” en España. 6. Uno de los objetivos fundamentales de esta tesis es el de regular esta figura cuando actúe en un proyecto, definir y realizar una estructura de Agente de la Edificación, según la Ley de Ordenación de la Edificación (LOE), y de esta manera poder introducirla dentro de la Legislación Española, protegiéndola de eventuales responsabilidades civiles. En España existe jurisprudencia (sentencias de los tribunales de justicia españoles) con jurisdicción civil basada en la LOE para absolver o condenar a agentes de la edificación que son definidos en los tribunales como “gestores constructivos” o similares. Por este motivo, en un futuro los tribunales podrían dictaminar responsabilidades solidarias entre el especialista “Lean Construction” y otros agentes del proyecto, dependiendo de sus actuaciones, y según se implemente el “Lean Project Delivery System”, el “Target Value Design” y el “Integrated Project Delivery”. Por otro lado, es posible que el nivel de actuación del especialista “Lean Construcción” pueda abarcar la gestión del diseño, la gestión de la ejecución material (construcción), la gestión de contratos, o la gestión integral de todo el proyecto de edificación, esto último, en concordancia con la última Norma ISO 21500:2012 o UNE-ISO 21500:2013 Directrices para la dirección y gestión de proyectos. En consecuencia, se debería incorporar adecuadamente a uno o más agentes de la edificación en la LOE de acuerdo a sus funciones y responsabilidades según los niveles de actuación del “Especialista en Lean Construction”. Se propone la creación de los siguientes agentes: Gestor del Diseño, Gestor Constructivo y Gestor de Contratos, cuyas definiciones están desarrolladas en este trabajo. Estas figuras son definidas de manera general, puesto que cualquier “Project Manager” o “DIPE”, gestor BIM (Building Information Modeling), o similar, puede actuar como uno o varios de ellos. También se propone la creación del agente “Gestor de la Construcción sin Pérdidas”, como aquel agente que asume las actuaciones del “gestor de diseño”, “gestor constructivo” y “gestor de contratos” con un enfoque en los principios del Lean Production. 7. En la tesis se demuestra, por medio del uso de la ISO 21500, que ambos sistemas son complementarios, de manera que los proyectos pueden tener ambos enfoques y ser compatibilizados. Un proyecto que use el “Project & Construction Management” puede perfectamente apoyarse en las herramientas y técnicas del “Lean Construction” para asegurar la eliminación o reducción de las pérdidas, es decir, las actividades que no generen valor, diseñando el sistema de producción, el sistema de diseño o el sistema de contratos. 8. Se debería incorporar adecuadamente al agente de la edificación “Especialista en Lean Construction” o similar y al agente ¨Especialista en Project & Construction Management” o DIPE en la Ley de Ordenación de la Edificación (LOE) de acuerdo a sus funciones y responsabilidades, puesto que la jurisprudencia se ha basado para absolver o condenar en la referida Ley. Uno de los objetivos fundamentales de esta tesis es el de regular la figura del “Especialista en Lean Construction” cuando actúa simultáneamente con el DIPE, y realizar una estructura de Agente de la Edificación según la LOE, y de esta manera protegerlo de eventuales responsabilidades solidarias. Esta investigación comprueba que la propuesta de definición del agente de edificación DIPE, según la LOE, presentada en la tesis doctoral del Doctor Manuel Soler Severino es compatible con las nuevas definiciones propuestas. El agente DIPE puede asumir los roles de los diferentes gestores propuestos en esta tesis si es que se especializa en dichas materias, o, si lo estima pertinente, recomendar sus contrataciones. ABSTRACT This work is based on the Lean Construction philosophy; an analysis is made herein with regard to the situation of this philosophy in the building sector within the international and Spanish context, replying to the following questions: 1. How did the concept of Lean Construction emerge? 2. Which are the activities, functions and objectives of Lean Construction? 3. Are there regulations on Lean Construction in other countries? 4. Is there a demand for Lean Construction in Spain? 5. Are there regulations on Lean Construction in Spain? 6. How should regulations on Lean Construction be developed in Spain? 7. What is the relationship between Lean Construction and the Project & Construction Management? 8. How should regulations on Lean Construction be developed in Spain considering its relationship with the Project & Construction Management? We have answered these questions in detail here and the replies are summarized as follows: 1. The concept of Lean Construction emerged in august of 1992, when Finnish researcher Lauri Koskela published in Stanford University TECHNICAL REPORT N° 72 entitled “Application of the New Production Philosophy to Construction”. A year later, Professor Koskela invited a group of construction specialists to Finland to the first workshop conducted on this matter; thus, the International Group for Lean Construction (IGLC) was established, which has contributed to extending the philosophy to the United States, Europe, the Americas, Asia, Oceania, and Africa. Lean Construction is a system based on the Lean Production approach, which was developed in Japan by Toyota Motors in the 1950s. Thanks to this system, the Toyota plants were able to produce more units, with greater efficiency than the American industry, less resources, in less time, and with fewer manufacturing errors. 2. The Lean Construction system aims at maximizing the value of projects while reducing waste, producing an effective coordination among those involved; it manages projects as a production system, enhancing collaboration between the parties that participate in the projects while building their capacities, empowering them, and promoting a culture of change. Its purpose is to develop a construction process free of accidents, without damages to the equipment, facilities, environment and community, flawless, in accordance with contractual requirements, within the terms established, respecting budgeted costs, and with a clear approach to eliminating or reducing waste, that is, activities that do not generate benefits. The Last Planner System is a Lean Construction system, which by its own nature protects planning and, therefore, helps to maximize the value and minimize waste, optimizing substantially the safety and health systems. Lean Construction started as a concept focused on the execution of works, and subsequently the philosophy was applied to all the stages of the project. At present it considers the project’s total development, since the time ideas are born until the completion and start-up of the work, taking into account the entire life cycle of the project. It is a philosophy of management, work methodologies, and entrepreneurial culture aimed at the effectiveness of processes and flows. The Lean Construction philosophy is extending all over the world and its scope is becoming broader, having greater influence on the contractual management of projects. It evolved initially through the creation of the Lean Project Delivery System, a global project development concept. Later on, the Target Value Design was developed, based on collaborative design to achieve the costs and value required, as well as the Integrated Project Delivery, in connection with integrated relational (collaborative) contract systems, as opposed to conventional contracts. 3. It was verified that no specific regulations on Lean Construction exist in other countries, in other words, there are no agents with the specific name of “Lean Construction Specialist” or other similar names; therefore, it is an additional agent in building projects, which functions and objectives can overlap those of the Project Manager, Construction Manager, Contract Manager, or Safety Manager, among others. However, the existence of private collaborative contracts of Integrated Project Delivery was confirmed, which could be considered as first references for future regulations. 4. There is a demand for Lean Construction in the development of this work; even though it is still emerging, there is a growing interest in this topic. 5. There are no regulations on Lean Construction in Spain. 6. One of the main objectives of this thesis is to regulate this role when acting in a project, and to define and develop a Building Agent structure, according to the Building Standards Law (LOE by its acronym in Spanish), in order to be able to incorporate it into the Spanish law, protecting it from civil liabilities. In Spain there is jurisprudence in civil jurisdiction based on the LOE to acquit or convict building agents, which are defined in the courts as “construction managers” or similar. For this reason, courts could establish in the future joint and several liabilities between the Lean Construction Specialist and other agents of the project, depending on their actions and based on the implementation of the Lean Project Delivery System, the Target Value Design, and the Integrated Project Delivery. On the other hand, it is possible that the level of action of the Lean Construction Specialist may comprise design management, construction management and contract management, or the integral management of the entire building project in accordance with the last ISO 21500:2012 or UNE-ISO 21500:2013, guidelines for the management of projects. Accordingly, one or more building agents should be appropriately incorporated into the LOE according to their functions and responsibilities and based on the levels of action of the Lean Construction Specialist. The creation of the following agents is proposed: Design Manager, Construction Manager, and Contract Manager, which definitions are developed in this work. These agents are defined in general, since any Project Manager or DIPE, Building Information Modeling (BIM) Manager or similar, may act as one or as many of them. The creation of the Lean Construction Manager is also proposed, as the agent that takes on the role of the Design Manager, Construction Manager and Contract Manager with a focus on the Lean Production principles. 7. In the thesis it is demonstrated that through the implementation of the ISO 21500, both systems are supplementary, so projects may have both approaches and be compatible. A project that applies the Project & Construction Management may perfectly have the support of the tools, techniques and practices of Lean Construction to ensure the elimination or reduction of losses, that is, those activities that do not generate value, thus designing the production system, the design system, or the contract system. 8. The Lean Construction Specialist or similar and the Specialist in Project & Construction Management should be incorporated appropriately into the LOE according to their functions and responsibilities, since jurisprudence has been based on such Law to acquit or convict. One of the main objectives of this thesis is the regulate the role of the Lean Construction Specialist when acting simultaneously with the DIPE, and to develop a structure of the building agent, according to the LOE, and in this way protect such agent from joint and several liabilities. This research proves that the proposal to define the DIPE building agent, according to the LOE, and presented in the doctoral dissertation of Manuel Soler Severino, Ph.D. is compatible with the new definitions proposed. The DIPE agent may assume the roles of the different managers proposed in this thesis if he specializes in those topics or, if deemed pertinent, recommends that they be engaged.

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The Internet has changed the way in which organizations communicate with their publics, and museums are not an exception. The consolidation of Web 2.0 has not only given museums access to a powerful new tool for disseminating information, but has involved significant changes in the relationship between institutions and their publics, facilitating and enhancing the interaction between them. The overall objective of this paper is to analyze the degree of interactivity implemented in the websites of major international art museums, in order to assess if museums are evolving towards more dialogic systems with relation to their publics. The results indicate that museums still have a low level of interactivity on their websites, both in the tools used to present information and the resources available for interaction with virtual visitors. But it has also observed that museums are progressively implementing interactive and dialogic sources, suggesting a clear trend towards new ways of managing these platforms in order to establish more participatory and collaborative communication systems with virtual users.