Wireless sensor networks may be deployed to retrieve visual information from the monitored field,... more Wireless sensor networks may be deployed to retrieve visual information from the monitored field, enriching monitoring and control applications. Whenever a set of camera-enabled sensor nodes are deployed for time-critical monitoring, visual information as still images and video streams may need to reach the sink as soon as possible, requiring a differentiated treating of the network when compared with non-critical visual data. In such way, considering that source nodes may have different sensing relevancies for the ...
Parallel Computing has become a powerful tool to overcome certain types of computational problems... more Parallel Computing has become a powerful tool to overcome certain types of computational problems in many areas such as engineering, especially due to the increasing diversity of platforms for execution of this type of application. The use of parallel computing over LANs and WANs is an alternative in the universe of dedicated environments (parallel machines and clusters), but, in some cases, it needs to imply QoS (Quality of Service) parameters, so it can execute efficiently. In this scenario, the deployment of resource allocation scheme plays an important role in order to satisfy the QoS requirements for parallel applications. In this paper we propose and present Markovian models for resource allocation (CPU allocation) schemes in a GPOS (General Purpose Operating Systems), aiming at offering an optimization method which makes the efficient performance of parallel and interactive applications feasible.
A smart transducer is the integration of a sensor/actuator element, a processing unit and a netwo... more A smart transducer is the integration of a sensor/actuator element, a processing unit and a network interface. Smart sensor networks are composed of smart transducer nodes interconnected through a communication network. This paper proposes a new architecture for smart sensor networks, that is driven by events (asynchronous data). The events are derived from a data compression algorithm embedded in the smart sensor, which compresses data from the sensor. The proposed architecture also provides configuration and monitoring data to manage the distributed system.
This work has the objective to present the first development results of a WirelessHART module for... more This work has the objective to present the first development results of a WirelessHART module for the ns-3. Our focus is the implementation of the Physical layer in order to provide the basis for the development of the superior layers such as MAC and Application. Thus, we presente an energy consumption model, a Gilbert/Elliot error model and an analysis for the currently avaliable ns-3 propagation loss models. For further development we mainly aim for the implementation of the time slot scheduler (Network Manager) and the development of an inter protocol simulation with mutual interference.
Due to the increased availability of low cost network technology, the use of networks to intercon... more Due to the increased availability of low cost network technology, the use of networks to interconnect sensors, actuators and controllers is now widely accepted. Such increased availability is one of the driving factors for the implementation of smart sensor networks. To ensure the correctness of the supported applications, the communication network must provide a reliable and timely communication service. Aside from the medium access control (MAC) protocol, one of the components that has a high impact in the communication delays is the local communication stack. Therefore, the usage of an adequate communication stack is of utmost importance to guarantee the timing correctness of the supported smart sensor applications. In this paper, we analyze the real-time aspects of a CAN-based smart sensor network. We assess the use of well established realtime scheduling algorithms to manage the outgoing queue of each of the local communication stacks. We show that it is possible to improve the responsiveness of applications supported by the CAN communication protocol, by using just a light scheduling middleware to adequately schedule each of the outgoing queues. We also show that implementing such middleware upon COTS communication hardware, it is possible to reduce the occurrence of priority inversions in the communication medium. Therefore it becomes possible to decrease the number of deadline misses even for highly loaded network scenarios. As a consequence, we advocate that CAN networks can be an interesting solution to support event-triggered smart sensor networks.
Abstract WirelessHART currently appears as a leading solution for interconnection of wireless dev... more Abstract WirelessHART currently appears as a leading solution for interconnection of wireless devices in industrial process control applications. However, the lack of knowledge about the influence of transient faults in WirelessHART networks can lead to the choice of less reliable topologies. In this work, we propose a simulation model to evaluate WirelessHART networks in the presence of transient faults. We assume that these faults result from noisy environments that disturb communications between devices. The model ...
The quality of service (QoS) is a core issue in multimedia systems. Intuitively, the QoS states h... more The quality of service (QoS) is a core issue in multimedia systems. Intuitively, the QoS states how good the services provided by a multimedia system are. As a rule, the QoS is established through negotiation between users and service providers. The negotiation involves allocation and management of resources in order to attain a desired level of quality. Examples of such resources are peripherals, CPU, network bandwidth, data formats and synchronization levels. The process of negotiation is simple if the resources are managed by a single entity (eg. operating system) or by a set of entities supporting a common negotiation protocol. Unfortunately, in distributed multimedia systems the negotiation and management of resources are far from being simple tasks since resources are diversified, distributed and managed by different entities. In order to minimize such difficulties, an agent-based architecture for QoS negotiation and management is proposed. The architecture combines fixed and mobile agents that interact with the aim of establishing and maintaining a certain level of QoS in a distributed multimedia system. This paper also describes a partial implementation of the proposed architecture using well accepted standards such as CORBA (Object Management Group's Common Object Request Broker Architecture), RTP (Internet's Real Time Protocol), products like Aglets Workbench (a Java based mobile agent framework from IBM) and the Orbix family from Iona
The design engineers need to use high level formalisms to facilitate the development, maintenance... more The design engineers need to use high level formalisms to facilitate the development, maintenance, and documentation of the industrial control systems. These formalisms must permit the modeling, formal validation, and code generation to PLC. This paper discusses statechart for modeling of industrial systems, and presents a case study that simulates the general schema of the industrial automation process, based in PLC. The case study was implemented with Java technologies, and was simulated using the execution environment developed by the Jakarta Project Commons SCXML.
Wireless sensor networks may be deployed to retrieve visual information from the monitored field,... more Wireless sensor networks may be deployed to retrieve visual information from the monitored field, enriching monitoring and control applications. Whenever a set of camera-enabled sensor nodes are deployed for time-critical monitoring, visual information as still images and video streams may need to reach the sink as soon as possible, requiring a differentiated treating of the network when compared with non-critical visual data. In such way, considering that source nodes may have different sensing relevancies for the ...
Parallel Computing has become a powerful tool to overcome certain types of computational problems... more Parallel Computing has become a powerful tool to overcome certain types of computational problems in many areas such as engineering, especially due to the increasing diversity of platforms for execution of this type of application. The use of parallel computing over LANs and WANs is an alternative in the universe of dedicated environments (parallel machines and clusters), but, in some cases, it needs to imply QoS (Quality of Service) parameters, so it can execute efficiently. In this scenario, the deployment of resource allocation scheme plays an important role in order to satisfy the QoS requirements for parallel applications. In this paper we propose and present Markovian models for resource allocation (CPU allocation) schemes in a GPOS (General Purpose Operating Systems), aiming at offering an optimization method which makes the efficient performance of parallel and interactive applications feasible.
A smart transducer is the integration of a sensor/actuator element, a processing unit and a netwo... more A smart transducer is the integration of a sensor/actuator element, a processing unit and a network interface. Smart sensor networks are composed of smart transducer nodes interconnected through a communication network. This paper proposes a new architecture for smart sensor networks, that is driven by events (asynchronous data). The events are derived from a data compression algorithm embedded in the smart sensor, which compresses data from the sensor. The proposed architecture also provides configuration and monitoring data to manage the distributed system.
This work has the objective to present the first development results of a WirelessHART module for... more This work has the objective to present the first development results of a WirelessHART module for the ns-3. Our focus is the implementation of the Physical layer in order to provide the basis for the development of the superior layers such as MAC and Application. Thus, we presente an energy consumption model, a Gilbert/Elliot error model and an analysis for the currently avaliable ns-3 propagation loss models. For further development we mainly aim for the implementation of the time slot scheduler (Network Manager) and the development of an inter protocol simulation with mutual interference.
Due to the increased availability of low cost network technology, the use of networks to intercon... more Due to the increased availability of low cost network technology, the use of networks to interconnect sensors, actuators and controllers is now widely accepted. Such increased availability is one of the driving factors for the implementation of smart sensor networks. To ensure the correctness of the supported applications, the communication network must provide a reliable and timely communication service. Aside from the medium access control (MAC) protocol, one of the components that has a high impact in the communication delays is the local communication stack. Therefore, the usage of an adequate communication stack is of utmost importance to guarantee the timing correctness of the supported smart sensor applications. In this paper, we analyze the real-time aspects of a CAN-based smart sensor network. We assess the use of well established realtime scheduling algorithms to manage the outgoing queue of each of the local communication stacks. We show that it is possible to improve the responsiveness of applications supported by the CAN communication protocol, by using just a light scheduling middleware to adequately schedule each of the outgoing queues. We also show that implementing such middleware upon COTS communication hardware, it is possible to reduce the occurrence of priority inversions in the communication medium. Therefore it becomes possible to decrease the number of deadline misses even for highly loaded network scenarios. As a consequence, we advocate that CAN networks can be an interesting solution to support event-triggered smart sensor networks.
Abstract WirelessHART currently appears as a leading solution for interconnection of wireless dev... more Abstract WirelessHART currently appears as a leading solution for interconnection of wireless devices in industrial process control applications. However, the lack of knowledge about the influence of transient faults in WirelessHART networks can lead to the choice of less reliable topologies. In this work, we propose a simulation model to evaluate WirelessHART networks in the presence of transient faults. We assume that these faults result from noisy environments that disturb communications between devices. The model ...
The quality of service (QoS) is a core issue in multimedia systems. Intuitively, the QoS states h... more The quality of service (QoS) is a core issue in multimedia systems. Intuitively, the QoS states how good the services provided by a multimedia system are. As a rule, the QoS is established through negotiation between users and service providers. The negotiation involves allocation and management of resources in order to attain a desired level of quality. Examples of such resources are peripherals, CPU, network bandwidth, data formats and synchronization levels. The process of negotiation is simple if the resources are managed by a single entity (eg. operating system) or by a set of entities supporting a common negotiation protocol. Unfortunately, in distributed multimedia systems the negotiation and management of resources are far from being simple tasks since resources are diversified, distributed and managed by different entities. In order to minimize such difficulties, an agent-based architecture for QoS negotiation and management is proposed. The architecture combines fixed and mobile agents that interact with the aim of establishing and maintaining a certain level of QoS in a distributed multimedia system. This paper also describes a partial implementation of the proposed architecture using well accepted standards such as CORBA (Object Management Group's Common Object Request Broker Architecture), RTP (Internet's Real Time Protocol), products like Aglets Workbench (a Java based mobile agent framework from IBM) and the Orbix family from Iona
The design engineers need to use high level formalisms to facilitate the development, maintenance... more The design engineers need to use high level formalisms to facilitate the development, maintenance, and documentation of the industrial control systems. These formalisms must permit the modeling, formal validation, and code generation to PLC. This paper discusses statechart for modeling of industrial systems, and presents a case study that simulates the general schema of the industrial automation process, based in PLC. The case study was implemented with Java technologies, and was simulated using the execution environment developed by the Jakarta Project Commons SCXML.
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