346,764 research outputs found

    Multiagent autonomous energy management

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    The objective of this thesis is to design distributed software agents for reliable operation of integrated electric power systems of modern electric warships. The automatic reconfiguration of electric shipboard power systems is an important step toward improved fight-through and self-healing capabilities of naval warships. The improvements are conceptualized by redesigning the electric power system and its controls. This research focuses on a new scheme for an energy management system in the form of distributed control/software agents. Multiagent systems provide an ideal level of abstraction for modeling complex applications where distributed and heterogeneous entities need to cooperate to achieve a common goal. The agents\u27 task is to ensure supply of the various load demands while taking into consideration system constraints and load and supply path priorities. A self-stabilizing maximum flow algorithm is investigated to allow implementation of the agents\u27 strategies and find a global solution by only considering local information and a minimum amount of communication. (Abstract shortened by UMI.)

    Semantic Integration of Identity Data Repositories

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    With the continuously growing number of distributed and heterogeneous IT systems there is the need for structured and efficient identity management (IdM) processes. This implies that new users are created once and then the information is distributed to all applicable software systems same as if changes on existing user objects occur. The central issue is that there is no generally ac-cepted standard for handling this information distribution because each system has its own internal representation of this data. Our approach is to give a se-mantic definition of the digital user objects attributes to ease the mapping process of an abstract user object to the concrete instantiation of each software system. Therefore we created an ontology to define the mapping of users at-tributes as well as an architecture which enables the semantic integration of identity data repositories. Our solution has been tested in an implementation case study

    The Role of Middleware in Distributed Energy Systems Integrated in the Smart Grid

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    Middleware architectures have proven to be of major importance when dealing with distributed systems, as they are able to abstract the inevitable heterogeneity of the hardware devices present in a deployment with the aim of offering a collection of interfaces and resources of homogeneous appearance to the upper, application‐oriented layers. In an energy‐based distributed system as the Smart Grid, this role is replicated, as the hardware devices that are found, while essentially related to the power grid and the functionalities that can be extracted from it (advanced metering infrastructure, remote terminal units, renewable energy resources, etc.), still present the same challenges that other distributed systems are expected to deal with, such as heterogeneous features, different information formats, diversity of their performance procedures, or integration and interconnectivity issues. Therefore, a middleware architecture is still of major usability in the power grid. This chapter offers information about the common features that are present in a middleware architecture that works under the requirements and use cases typical of the Smart Grid, as well as offers examples on how middleware integrates legacy, proprietary, and newly developed pieces of equipment within the same distributed energy grid

    A scalable middleware-based infrastructure for energy management and visualization in city districts

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    Following the Smart City views, citizens, policy makers and energy distribution companies need a reliable and scalable infrastructure to manage and analyse energy consumption data in a city district context. In order to move forward this view, a city district model is needed, which takes into account different data-sources such as Building Information Models, Geographic Information Systems and real-time information coming from heterogeneous devices in the district. The Internet of Things paradigm is creating new business opportunities for low-cost, low-power and high-performance devices. Nevertheless, because of the "smart devices" heterogeneity, in order to provide uniform access to their functionalities, an abstract point of view is needed. Therefore, we propose an distributed software infrastructure, exploiting service-oriented middleware and ontology solutions to cope with the management, simulation and visualization of district energy data

    A Framework for Interoperable Healthcare Information Systems

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    Abstract: It is clear that in today's organizations, new and existing applications require access to data stored in several preexisting databases held at several local and remote locations. Therefore, a main criterion required by most complex organizations, is the provision of collaboration possibilities and information integration mechanisms among distributed, heterogeneous, and autonomous database systems. The development of an application provides interoperability and information integration among distributed systems, via the deployment of database standards and emerging Internet technologies. It is one of the most challenging approaches in the area of integrating heterogeneous information from autonomous sites. In this context, the work described in this paper focuses on the design and development of a Generic Information Exchange (GIE) System. The system supports a wide variety of applications with efficient means for their interconnection and interoperation, while preserving their heterogeneity, distribution, and full autonomy. An example of the interoperability problem is found in the healthcare domain, where each hospital, or even each department in a hospital, maintains its own database. In this environment it is very important to permit users to locate and access data from several remote databases, supporting the needs of patient care, daily operations of the hospitals and research consultations. It necessitates the sharing and exchange of data related to clinical, administrative, managerial and research (statistical) information. Therefore, it is necessary to propose an approach i.e. GIE System that permits interoperation among heterogeneous, distributed, and autonomous sites

    Adaptive structured parallelism

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    Algorithmic skeletons abstract commonly-used patterns of parallel computation, communication, and interaction. Parallel programs are expressed by interweaving parameterised skeletons analogously to the way in which structured sequential programs are developed, using well-defined constructs. Skeletons provide top-down design composition and control inheritance throughout the program structure. Based on the algorithmic skeleton concept, structured parallelism provides a high-level parallel programming technique which allows the conceptual description of parallel programs whilst fostering platform independence and algorithm abstraction. By decoupling the algorithm specification from machine-dependent structural considerations, structured parallelism allows programmers to code programs regardless of how the computation and communications will be executed in the system platform.Meanwhile, large non-dedicated multiprocessing systems have long posed a challenge to known distributed systems programming techniques as a result of the inherent heterogeneity and dynamism of their resources. Scant research has been devoted to the use of structural information provided by skeletons in adaptively improving program performance, based on resource utilisation. This thesis presents a methodology to improve skeletal parallel programming in heterogeneous distributed systems by introducing adaptivity through resource awareness. As we hypothesise that a skeletal program should be able to adapt to the dynamic resource conditions over time using its structural forecasting information, we have developed ASPara: Adaptive Structured Parallelism. ASPara is a generic methodology to incorporate structural information at compilation into a parallel program, which will help it to adapt at execution

    SOA-Based Model for Value-Added ITS Services Delivery

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    Integration is currently a key factor in intelligent transportation systems (ITS), especially because of the ever increasing service demands originating from the ITS industry and ITS users. The current ITS landscape is made up of multiple technologies that are tightly coupled, and its interoperability is extremely low, which limits ITS services generation. Given this fact, novel information technologies (IT) based on the service-oriented architecture (SOA) paradigm have begun to introduce new ways to address this problem. The SOA paradigm allows the construction of loosely coupled distributed systems that can help to integrate the heterogeneous systems that are part of ITS. In this paper, we focus on developing an SOA-based model for integrating information technologies (IT) into ITS to achieve ITS service delivery. To develop our model, the ITS technologies and services involved were identified, catalogued, and decoupled. In doing so, we applied our SOA-based model to integrate all of the ITS technologies and services, ranging from the lowest-level technical components, such as roadside unit as a service (RS S), to the most abstract ITS services that will be offered to ITS users (value-added services). To validate our model, a functionality case study that included all of the components of our model was designed

    CDI/THREDDS interoperability in the SeaDataNet framework

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    Abstract. SeaDataNet is an EU funded project aiming to create and operate a pan-European, marine data infrastructure for managing the large and diverse datasets (i.e. temperature, salinity current, sea level, chemical, physical and biological properties) collected by the oceanographic fleets and the new automatic observation systems. In order to make the SeaDataNet system compliant with the INSPIRE Implementing Rules for discovery service, an ISO 19139 encoding of the SeaDataNet Common Data Index (CDI) metadata model was defined. Moreover, the problem of heterogeneous data sources has been addressed. In fact, a widely used system of SeaDataNet partners and oceanographic-marine community is THREDDS/OPeNDAP; this raises up the problem of federating into SeaDataNet framework THREDDS/OPeNDAP systems as well. In this paper we describe an interoperability framework to access resources (i.e. data and services) that are available through CDI and THREDDS/OPeNDAP services. The proposed solution implements a common catalog interface to discover and access the two heterogeneous resources in a common way. This catalog service is fully distributed and implements international standards as far as geospatial information discovery and query are concerned. The developed solution is called GI-cat and was experimented in the framework of the SeaDataNet European project
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