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Publicações

Publicações por HumanISE

2017

Combining dataflow applications and real-time task sets on multi-core platforms

Autores
Ali, HI; Akesson, B; Pinho, LM;

Publicação
Proceedings of the 20th International Workshop on Software and Compilers for Embedded Systems, SCOPES 2017

Abstract
Future real-time embedded systems will increasingly incorporate mixed application models with timing constraints running on the same multi-core platform. These application models are dataflow applications with timing constraints and traditional real-time applications modelled as independent arbitrary-deadline tasks. These systems require guarantees that all running applications execute satisfying their timing constraints. Also, to be cost-efficient in terms of design, they require efficient mapping strategies that maximize the use of system resources to reduce the overall cost. This work proposes an approach to integrate mixed application models (dataflow and traditional real-time applications) with timing requirements on the same multi-core platform. It comprises three main algorithms: 1) Slack-Based Merging, 2) Timing Parameter Extraction, and 3) Communication-Aware Mapping. Together, these three algorithms play a part in allowing mapping and scheduling of mixed application models in embedded real-time systems. The complete approach and the three algorithms presented have been validated through proofs and experimental evaluation. © 2017 Copyright held by the owner/author(s).

2017

Real-time semi-partitioned scheduling of fork-join tasks using work-stealing

Autores
Maia, C; Yomsi, PM; Nogueira, L; Pinho, LM;

Publicação
EURASIP JOURNAL ON EMBEDDED SYSTEMS

Abstract
This paper extends the work presented in Maia et al. (Semi-partitioned scheduling of fork-join tasks using work-stealing, 2015) where we address the semi-partitioned scheduling of real-time fork-join tasks on multicore platforms. The proposed approach consists of two phases: an offline phase where we adopt a multi-frame task model to perform the task-to-core mapping so as to improve the schedulability and the performance of the system and an online phase where we use the work-stealing algorithm to exploit tasks' parallelism among cores with the aim of improving the system responsiveness. The objective of this work is twofold: (1) to provide an alternative scheduling technique that takes advantage of the semi-partitioned properties to accommodate fork-join tasks that cannot be scheduled in any pure partitioned environment and (2) to reduce the migration overheads which has been shown to be a traditional major source of non-determinism for global scheduling approaches. In this paper, we consider different allocation heuristics and we evaluate the behavior of two of them when they are integrated within our approach. The simulation results show an improvement up to 15% of the proposed heuristic over the state-of-the-art in terms of the average response time per task set.

2017

Erratum to: Optimal minimal routing and priority assignment for priority-preemptive real-time NoCs (Real-Time Systems, (2017), 53, 4, (578-612), 10.1007/s11241-017-9273-8)

Autores
Nikolic B.; Pinho L.M.;

Publicação
Real-Time Systems

Abstract
The original version of this article unfortunately contained an error in the author affiliation. The corresponding author, “Dr. Borislav Nikoli´c” is currently affiliated in “Technische Universität Braunschweig”, but the work of this paper was performed and funded by CISTER/INESC-TEC, ISEP, IPP. Therefore, the corresponding author is linked to both the affiliations. This has been corrected with this erratum.

2017

Optimal minimal routing and priority assignment for priority-preemptive real-time NoCs

Autores
Nikolic, B; Pinho, LM;

Publicação
REAL-TIME SYSTEMS

Abstract
The Network-on-Chip (NoC) architecture is an interconnect network with a good performance and scalability potential. Thus, it comes as no surprise that NoCs are among the most popular interconnect mediums in nowadays available many-core platforms. Over the years, the real-time community has been attempting to make NoCs amenable to the real-time analysis. One such approach advocates to employ virtual channels. Virtual channels are hardware resources that can be used as an infrastructure to facilitate flit-level preemptions between communication traffic flows. This gives the possibility to implement priority-preemptive arbitration policies in routers, which is a promising step towards deriving real-time guarantees for NoC traffic. So far, various aspects of priority-preemptive NoCs were studied, such as arbitration, priority assignment, routing, and workload mapping. Due to a potentially large solution space, the majority of available techniques are heuristic-centric, that is, either pure heuristics, or heuristic-based search strategies are used. Such approaches may lead to an inefficient use of hardware resources, and may cause a resource over-provisioning as well as unnecessarily high design-cost expenses. Motivated by this reality, we take a different approach, and propose an integer linear program to solve the problems of priority assignment and routing of NoC traffic. The proposed method finds optimal routes and priorities, but also allows to reduce the search space (and the computation time) by fixing either priorities or routes, and derive optimal values for remaining parameters. This framework is used to experimentally evaluate both the scalability of the proposed method, as well as the efficiency of existing priority assignment and routing techniques.

2017

Smart City Governance

Autores
Bernardo, MdRM;

Publicação
Handbook of Research on Entrepreneurial Development and Innovation Within Smart Cities - Advances in Environmental Engineering and Green Technologies

Abstract
Smart governance is one of the characteristics of smart cities, having its roots in e-government, in the principles of good governance, and in the assumptions of citizens' participation and involvement in public decision-making. This chapter aims to answer the question: “What smart governance practices are being implemented in smart cities” through an extensive literature review in the areas of e-government, good governance, smart cities and smart governance, and content analysis of the websites of seven smart cities: Amsterdam, Barcelona, Copenhagen, Lisbon, Manchester, Singapore, and Stockholm. The objective was to identify the presence of factors related with e-participation; e-services; and public administration functioning on the cities' websites. The chapter ends with directions for future research and the conclusion that all the smart cities analyzed presented some factors related with smart governance, but with different levels of development and application.

2017

Considerações éticas, epistemológicas e metodológicas sobre o fazer pesquisa em educação e cultura digital

Autores
Lopes, DdQ; Schlemmer, E;

Publicação
Revista EDaPECI

Abstract
O presente artigo problematiza aspectos éticos, epistemológicos e metodológicos relacionados ao campo da pesquisa em educação e cultura digital. A partir da reflexão sobre como a ética pode dialogar com as escolhas ao se fazer pesquisa, apresenta os caminhos adotados no contexto de duas pesquisas conduzidas entre os anos de 2010 e 2015 junto a uma escola pública estadual da região metropolitana de Porto Alegre participante de programas governamentais de inclusão digital. Com base no método cartográfico de pesquisa e intervenção, apresenta alguns dos resultados das discussões realizadas junto a professores e estudantes a partir da experiência de produzir e publicar informações na Internet. Problematiza o dilema ético da pesquisa-intervenção com base na ideia de apropriação tecnológica como um processo que se estabelece a partir das mudanças de significado sobre práticas que se produzem em contextos da cultura escolar analógica e da cultura digital. Discute e propõe, com base nos resultados da pesquisa, a superação do dilema ético relacionado à participação de crianças e jovens estudantes em pesquisas que envolvam a publicação de conteúdo online e os receios com relação à exposição midiática – produção e acesso a conteúdo inadequado – e à desatenção em sala de aula.

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