| 1. |
- Bassi, Ezio, et al.
(författare)
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Powerline Communication in Electric Vehicles
- 2009
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Ingår i: IEEE International Electric Machines and Drives Conference (IEMDC'09). - 9781424442522 ; , s. 1749-1753
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Konferensbidrag (refereegranskat)abstract
- In full electric (EV) or hybrid electric (HEV) vehicles the onboard communication is a crucial issue, that can take advantage from a reliable and robust interaction among the embedded units (ECUs) providing among others the power and batteries management, services, accessories and supervision; an updated global view of the system under control (the car) can improve the quality of control, reliability, safety and comfort. Power Line Communication technology (PLC), that take advantage of the DC power line as a physical medium to exchange messages, according to standard protocols, is a candidate at substituting the actual wired solutions, by substantially reducing the cabling burden. The present paper aims at i) reviewing PLC technology for DC bus in the automotive sector; ii) defining the requirements of a reliable communication systems within a car environment, with special attention given to the data exchange needed by the more critical systems in EV and HEV, and namely the control of electrical actuators for traction; iii) describing a benchmark for testing the data transfer characteristics and performance, including details on proposed protocols and architectures and presenting experimental results on data channel characterization and transmission.
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| 2. |
- Benzi, Francesco, et al.
(författare)
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Towards the Powerline Alternative in Automotive Applications
- 2008
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Ingår i: Proceedings of the Work-In-Progress (WIP) session of the 7th IEEE International Workshop on Factory Communication Systems (WFCS'08), Dresden, Germany. - 9781424423491 ; , s. 259-262
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Konferensbidrag (refereegranskat)abstract
- The Power Line technology has received an increasing attention in the last decades due to its inherent benefits, mainly related to the reduction of cabling and associated costs. Power Line Communication (PLC) was first employed in power utilities and since the 80s in home automation, too. However, its use in the automotive field received relatively little attention. This paper revisits the related work in using PLC technology for communication within the automotive domain and outlines its possible benefits. Then, it focuses on the issues that need to be addressed when introducing the PLC in the automotive domain. The final goal of this work is to carry out a practical assessment of the PLC technology in the referred domain that may open the way for future use in industrial scale.
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| 3. |
- Ferreira da Silva, Eduardo, et al.
(författare)
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Heavy metal pollution downstream the abandoned Coval da Mó mine (Portugal) and associated effects on epilithic diatom communities
- 2009
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 407:21, s. 5620-5636
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Tidskriftsartikel (refereegranskat)abstract
- This study examined trace-element concentrations in 39 sediment samples collected in the vicinity of the abandoned Coval da Mó mine, and evaluated the anthropogenic contaminant effects and other environmental variables in the taxonomic composition, structure and morphological changes of benthic diatom communities.The results show the existence of extremely high contamination in Pb, Zn and Cd (the mean values exceed the background values 376, 96 and 19 times, respectively) on the first 2.5 km in the water flow direction. Also Co, Cu, Mn and Ni are present in high concentrations. Dilution by relatively uncontaminated sediment reduces metal concentrations downstream, but Zn concentrations increase downstream Fílvida stream, as a result of several factors such as sewage and agriculture.To evaluate the biological effects caused by Pb, Cd and Zn, three sites were selected. In the stressed environment, near the mining area (C232), diatoms were extremely rare, however there was a slight recovery at site C79 located 2 km downstream. Fragilaria capucina var. rumpens, Fragilaria cf. crotonensis and Achnanthidium minutissimum showed abnormal valves which may be related to high levels of metals.Six km downstream, in Fílvida stream (C85), an increase in species richness and diversity was registered while the relative percentage of valve teratologies was lower. In the absence of OM, nutrients and low pH the diatom community patterns must be attributed to the metal concentration at some sites. Considering that community diversity can be affected by abiotic and biotic variables and valve deformations are caused by a small number of variables, basically metals, and acid conditions, we consider the presence of teratologies as an indication of the presence of metals.
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| 4. |
- Hjertström, Andreas, 1972-
(författare)
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Information Centric Development of Component-Based Embedded Real-Time Systems
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents new techniques for data management of run-time data objectsin component-based embedded real-time systems. These techniques enabledata to be modeled, analyzed and structured to achieve data managementduring development, maintenance and execution.The evolution of real-time embedded systems has resulted in an increasedsystem complexity beyond what was thought possible just a few years ago.Over the years, new techniques and tools have been developed to manage softwareand communication complexity. However, as this thesis show, currenttechniques and tools for data management are not sufficient. Today, developmentof real-time embedded systems focuses on the function aspects of thesystem, in most cases disregarding data management.The lack of proper design-time data management often results in ineffectivedocumentation routines and poor overall system knowledge. Contemporarytechniques to manage run-time data do not satisfy demands on flexibility,maintainability and extensibility. Based on an industrial case-study that identifiesa number of problems within current data management techniques, bothduring design-time and run-time, it is clear that data management needs to beincorporated as an integral part of the development of the entire system architecture.As a remedy to the identified problems, we propose a design-time data entityapproach, where the importance of data in the system is elevated to beincluded in the entire design phase with proper documentation, properties, dependenciesand analysis methods to increase the overall system knowledge.Furthermore, to efficiently manage data during run-time, we introduce databaseproxies to enable the fusion between two existing techniques; ComponentBased Software Engineering (CBSE) and Real-Time Database ManagementSystems (RTDBMS). A database proxy allows components to be decoupledfrom the underlying data management strategy without violating the componentencapsulation and communication interface.
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| 5. |
- Hoang, Hoai, 1976-
(författare)
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Enhancing the Performance of Distributed Real-time Systems
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Advanced embedded systems can consist of many sensors, actuators and processors that are deployed on one or several boards, while having a demand of interacting with each other and sharing resources. Communication between different components usually has strict timing constraints. There is thus a strong need to provide solutions for time critical communication. This thesis focuses on both the support of real-time services over standard switched Ethernet networks and the improvement of systems' real-time characteristics, such as reducing delay and jitter in processors and on communication links.Switched Ethernet has been chosen in this work because of its major advantages in industry; it supports higher bit-rates than most other current LAN (Local Area Network) technologies, including field buses, still at a low cost. We propose using a star network topology with a single Ethernet switch. Each node is connected to a separate port of the switch via a full-duplex link, thereby eliminating collisions. A solid real-time communication protocol for switched Ethernet networks is proposed in the thesis, including a real-time layer between the Ethernet layer and the TCP/IP suite. The network has the capability of supporting both real-time and non real-time traffic and assuring adaptation to the surrounding protocol standards.Most embedded systems work in a dynamic environment, where the precise behavior of the network traffic can usually not be predicted. To support real-time services, we have chosen the Earliest Deadline scheduling algorithm (EDF) because of its optimality, high efficiency and suitability for being used in adaptive schemes. To be able to increase the amount of guaranteed real-time traffic, the notion of Asymmetric Deadline Partitioning Scheme (ADPS) is introduced. ADPS allows distribution of the end-to-end deadline of a message, sent from any source node in the network to any destination node via the switch, into two sub-deadlines, one for each hop according to the load of the physical link that it must traverse.For the EDF scheduling algorithm, the feasibility test is one of the most important techniques that provides us with information about whether or not the real-time traffic can be guaranteed by the network. With the same computational complexity as the feasibility test, a method has been developed to compute the minimum EDF-feasible deadline for a real-time task. The importance of this method in real-time applications lies in that it can be effectively used to reduce the response times of specific control activities or limit their input-output jitter. To allow more flexibility in the control of delay and jitter in real-time systems, a general approach for reducing task deadlines according to the requirements of individual tasks has been developed. The method allows the user to specify a deadline reduction factor for each task in order to better exploit the available slack according to the tasks' actual requirements.
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| 6. |
- Kourtessis, Pandelis, et al.
(författare)
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Evolution of Optical Access Networks
- 2009
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Ingår i: COST 291 - Towards Digital Optical Networks. - : Springer.
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Bokkapitel (refereegranskat)
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| 7. |
- Marau, Ricardo, et al.
(författare)
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Server-based real-time communications of Switched Ethernet
- 2008
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Ingår i: Proceedings of the 1st Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS'08) in conjunction with the 29th IEEE International Real-Time Systems Symposium (RTSS'08), Barcelona, Spain.
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Konferensbidrag (refereegranskat)
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| 8. |
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| 9. |
- Nolte, Thomas, 1977-
(författare)
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Share-Driven Scheduling of Embedded Networks
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many products are built from more or less independently developed subsystems. For instance, a car consists of subsystems for transmission, braking, suspension, etc. These subsystems are frequently controlled by an embedded computer system. In the automotive industry, as well as in other application domains, there is currently a trend from an approach where subsystems have dedicated computer hardware and other resources (a federated approach) to an approach where subsystems share hardware and other resources (an integrated approach). This is motivated by a strong pressure to reduce product cost, at the same time as an increasing number of subsystems are being introduced.When integrating subsystems, it is desirable that guarantees valid before integration are also valid after integration, since this would eliminate the need for costly reverifications. The computer network is a resource that is typically shared among all subsystems. Hence, a central issue when integrating subsystems is to provide an efficient scheduling of message transmissions on the network. There are essentially three families of schedulers that can be used: priority-driven schedulers that assign priorities to messages, time-driven schedulers that assign specific time-slots for transmission of specific messages, and share-driven schedulers that assign shares of the available network capacity to groups of messages.This thesis presents a framework for share-driven scheduling, to be implemented and used in embedded networks, with the aim to facilitate subsystem integration by reducing the risk of interference between subsystems. The framework is applied in the automotive domain.The initial parts of the thesis give an overview of systems, subsystems and network technologies found and used in the automotive domain. Then, the share-driven scheduling framework is presented, analytically investigated and proven, as well as evaluated in a simulation study. Finally it is shown how the framework is to be configured and used in the context of subsystem integration. The results show that the framework allows for flexible and efficient scheduling of messages with real-time constraints, facilitating integration of subsystems from a network point of view.
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| 10. |
- Pop, Traian, 1975-
(författare)
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Analysis and Optimisation of Distributed Embedded Systems with Heterogeneous Scheduling Policies
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The growing amount and diversity of functions to be implemented by the current and future embedded applications (like, for example, in automotive electronics) have shown that, in many cases, time-triggered and event-triggered functions have to coexist on the computing nodes and to interact over the communication infrastructure. When time-triggered and event-triggered activities have to share the same processing node, a natural way for the execution support can be provided through a hierarchical scheduler. Similarly, when such heterogeneous applications are mapped over a distributed architecture, the communication infrastructure should allow for message exchange in both time-triggered and event-triggered manner in order to ensure a straightforward interconnection of heterogeneous components.This thesis studies aspects related to the analysis and design optimisation for safety-critical hard real-time applications running on hierarchically scheduled distributed embedded systems. It first provides the basis for the timing analysis of the activities in such a system, by carefully taking into consideration all the interferences that appear at run-time between the processes executed according to different scheduling policies. Moreover, due to the distributed nature of the architecture, message delays are also taken into consideration during the timing analysis. Once the schedulability analysis has been provided, the entire system can be optimised by adjusting its configuration parameters. In our work, the entire optimisation process is directed by the results from the timing analysis, with the goal that in the end the timing constraints of the application are satisfied. The analysis and design methodology proposed in the first part of the thesis is applied next on the particular category of distributed systems that use FlexRay as a communication protocol. We start by providing a schedulability analysis for messages transmitted over a FlexRay bus, and then by proposing a bus access optimisation algorithm that aims at improving the timing properties of the entire system.For all the problems that we investigated, we have carried out extensive experiments in order to measure the efficiency of the proposed solutions. The results have confirmed both the importance of the addressed aspects during system-level design, and the applicability of our techniques for analysing and optimising the studied systems.
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