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- An architecture for reliable distributed computer-controlled systemsPublication . Pinho, Luís Miguel; Vasques, FranciscoIn Distributed Computer-Controlled Systems (DCCS), both real-time and reliability requirements are of major concern. Architectures for DCCS must be designed considering the integration of processing nodes and the underlying communication infrastructure. Such integration must be provided by appropriate software support services. In this paper, an architecture for DCCS is presented, its structure is outlined, and the services provided by the support software are presented. These are considered in order to guarantee the real-time and reliability requirements placed by current and future systems.
- An Energy Flexibility Framework on The Internet of ThingsPublication . Le Guilly, Thibaut; Siksnys, Laurynas; Albano, Michele; Pedersen, Per; Stluka, Petr; Lino Ferreira, Luis; Skou, Arne; Pedersen, Torben; Olsen, PeturThis paper presents a framework for management of flexible energy loads in the context of the Internet of Things and the Smart Grid. The framework takes place in the European project Arrowhead, and aims at taking advantage of the flexibility (in time and power) of energy production and consumption offered by sets of devices, appliances or buildings, to help at solving the issue of fluctuating energy production of renewable energies. The underlying concepts are explained, the actors involved in the framework, their incentives and interactions are detailed, and a technical overview is provided. An implementation of the framework is presented, as well as the expected results of the pilots.
- An implicit GTS allocation mechanism in IEEE 802.15.4 for time-sensitive wireless sensor networks: theory and practicePublication . Koubâa, Anis; Alves, Mário; Tovar, Eduardo; Cunha, AndréTimeliness guarantee is an important feature of the recently standardized IEEE 802.15.4 protocol, turning it quite appealing for Wireless Sensor Network (WSN) applications under timing constraints. When operating in beacon-enabled mode, this protocol allows nodes with real-time requirements to allocate Guaranteed Time Slots (GTS) in the contention-free period. The protocol natively supports explicit GTS allocation, i.e. a node allocates a number of time slots in each superframe for exclusive use. The limitation of this explicit GTS allocation is that GTS resources may quickly disappear, since a maximum of seven GTSs can be allocated in each superframe, preventing other nodes to benefit from guaranteed service. Moreover, the GTS may be underutilized, resulting in wasted bandwidth. To overcome these limitations, this paper proposes i-GAME, an implicit GTS Allocation Mechanism in beacon-enabled IEEE 802.15.4 networks. The allocation is based on implicit GTS allocation requests, taking into account the traffic specifications and the delay requirements of the flows. The i-GAME approach enables the use of one GTS by multiple nodes, still guaranteeing that all their (delay, bandwidth) requirements are satisfied. For that purpose, we propose an admission control algorithm that enables to decide whether to accept a new GTS allocation request or not, based not only on the remaining time slots, but also on the traffic specifications of the flows, their delay requirements and the available bandwidth resources. We show that our approach improves the bandwidth utilization as compared to the native explicit allocation mechanism defined in the IEEE 802.15.4 standard. We also present some practical considerations for the implementation of i-GAME, ensuring backward compatibility with the IEEE 801.5.4 standard with only minor add-ons. Finally, an experimental evaluation on a real system that validates our theoretical analysis and demonstrates the implementation of i-GAME is also presented
- Application system and services: design and implementation - a cook bookPublication . Delsing, Jerker; Albano, Michele; Ferreira, Luís Lino; Blomstedt, Frederik; Olovsson, Per; Varga, PalIn previous chapters local automation clouds and a SOA based architecture supporting the design and implementation of IoT based automation systems. This chapter is devoted to design and implement of application services. The ambition is to discuss: • Design of an Arrowhead Framework system • Implementation of such system and its services • Interoperability test
- Application system design – energy optimizationPublication . Albano, Michele; Castiñeira, Rodrigo; Desdouits, Chloé; Lino Ferreira, Luis; Le Guilly, Thibaut; Isasa, Inge; Jokinen, Jani; Kondratjevs, Kaspars; Kunicina, Nadezhda; Manero, Lorenzo; Milo, Aitor; Monge, Javier; Le Pape, Claude; Pedersen, Per; Pedersen, Torben; Olsen, Petur; Siksnys, Laurynas; Skou, Arne; Stluka, Petr; Zabasta, AnatolijsIn this chapter, we present a number of applications of the Arrowhead Framework with special attention to services related to awareness and optimization of energy consumption. First, we present the notion of FlexOffers as a general mechanism for describing energy flexibility. FlexOffers can be aggregated into larger flexibility units to be used as an Arrowhead service in the virtual market of energy [1]. This is followed by two examples on how to exploit such a flexibility service in the energy management of heatpumps and a campus building. Then we present two examples on how to exploit renewable energy to provide elevator services. Next, two examples of context aware services are described – smart lighting and smart car heating, and finally it is described how the Arrowhead Framework can play a role in the optimization of municipal service systems. In the final section, we indicate future work.
- Arrowhead Framework core systems and servicesPublication . Delsing, Jerker; Eliasson, Jens; Albano, Michele; Varga, Pal; Ferreira, Luís Lino; Derhamy, Hasan; Hegedus, Csaba; Puñal Pereira, Pablo; Carlsson, OscarIn chapter 2 local clouds was discussed followed by a local cloud automation architecture in chapter 3. The automation architecture supports the implementation of local automation clouds. Such implementation is supported by the Arrowhead Framework and its core Systems and Services. The Arrowhead Framework core systems enables the creation and operation of local clouds. First implementation of these systems and their services are described in detail in this chapter. There currently are two types of core services within the Arrowhead Framework: - Mandatory core systems - needed to establish the minimal local cloud - Automation support core systems – extending local cloud capabilities intending to provide support for the design and operation of local automation clouds an interaction between local clouds.
- Building a microscope for the data centerPublication . Pereira, Nuno; Tennina, Stefano; Tovar, EduardoManaging the physical and compute infrastructure of a large data center is an embodiment of a Cyber-Physical System (CPS). The physical parameters of the data center (such as power, temperature, pressure, humidity) are tightly coupled with computations, even more so in upcoming data centers, where the location of workloads can vary substantially due, for example, to workloads being moved in a cloud infrastructure hosted in the data center. In this paper, we describe a data collection and distribution architecture that enables gathering physical parameters of a large data center at a very high temporal and spatial resolutionof the sensor measurements. We think this is an important characteristic to enable more accurate heat-flow models of the data center andwith them, _and opportunities to optimize energy consumption. Havinga high resolution picture of the data center conditions, also enables minimizing local hotspots, perform more accurate predictive maintenance (pending failures in cooling and other infrastructure equipment can be more promptly detected) and more accurate billing. We detail this architecture and define the structure of the underlying messaging system that is used to collect and distribute the data. Finally, we show the results of a preliminary study of a typical data center radio environment.
- Communication response time in P-NET networks: worst-case analysis considering the actual token utilisationPublication . Tovar, Eduardo; Vasques, Francisco; Burns, AlanFieldbus networks aim at the interconnection of field devices such as sensors, actuators and small controllers. Therefore, they are an effective technology upon which Distributed Computer Controlled Systems (DCCS) can be built. DCCS impose strict timeliness requirements to the communication network. In essence, by timeliness requirements we mean that traffic must be sent and received within a bounded interval, otherwise a timing fault is said to occur. P-NET is a multi-master fieldbus standard based on a virtual token passing scheme. In P-NET each master is allowed to transmit only one message per token visit, which means that in the worst-case the communication response time could be derived considering that the token is fully utilised by all stations. However, such analysis can be proved to be quite pessimistic. In this paper we propose a more sophisticated P-NET timing analysis model, which considers the actual token utilisation by different masters. The major contribution of this model is to provide a less pessimistic, and thus more accurate, analysis for the evaluation of the worst-case communication response time in P-NET fieldbus networks.
- Development of a Hardware in the Loop Ad- Hoc Testbed for Cooperative Vehicles PlatooningPublication . Vasconcelos Filho, Ênio; Mendes, Bruno; Santos, Pedro M.; Tovar, EduardoCooperative Cyber-Physical Devices (Co-CPS) are reaching into the most diverse areas and pose new integration challenges. This is particularly true between cooperative autonomous machines, where safety and reliability must often be guaranteed without human presence. Among these scenarios, Cooperative Vehicular Platooning (Co-VP) applications present an exciting promise: improving road occupation, reducing accidents, and providing fuel savings. However, due to their high complexity and safety-critical characteristics, these applications must be validated to ensure their reliability before being applied in real scenarios, particularly regarding their underlying communication transactions. This paper presents an architecture for validating a Co-VP system via Hardware In the Loop (HIL) integration of IEEE 802.11 communications, and co-simulation support of a 3D simulator. We propose a use case with one scenario of communication profile according to the ETSI IT-G5 model and information exchange frequencies between the vehicles. Through these scenarios that mimic realistic conditions of Co-VP applications, we observe the impacts of such variations on the number of messages, network delays, and lateral and longitudinal platoon errors.
- Efficient computation of min and max sensor values in multihop networksPublication . Pereira, Nuno; Andersson, Björn; Tovar, Eduardo; Carvalho, PauloConsider a wireless sensor network (WSN) where a broadcast from a sensor node does not reach all sensor nodes in the network; such networks are often called multihop networks. Sensor nodes take individual sensor readings, however, in many cases, it is relevant to compute aggregated quantities of these readings. In fact, the minimum and maximum of all sensor readings at an instant are often interesting because they indicate abnormal behavior, for example if the maximum temperature is very high then it may be that a fire has broken out. In this context, we propose an algorithm for computing the min or max of sensor readings in a multihop network. This algorithm has the particularly interesting property of having a time complexity that does not depend on the number of sensor nodes; only the network diameter and the range of the value domain of sensor readings matter.