Real-time scheduling of parallel tasks in the Linux Kernel

This paper proposes a global multiprocessor scheduling algorithm for the Linux kernel that combines the global EDF scheduler with a priority-aware work-stealing load balancing scheme, enabling parallel real-time tasks to be executed on more than one processor at a given time instant. We state that some priority inversion may actually be acceptable, provided it helps reduce contention, communication, synchronisation and coordination between parallel threads, while still guaranteeing the expected system’s predictability. Experimental results demonstrate the low scheduling overhead of the proposed approach comparatively to an existing real-time deadline-oriented scheduling class for the Linux kernel

Materiais para o fim do mundo 6

Para estudar o imaginário do fim do mundo, o Instituto de Literatura Comparada Margarida Losa organiza, desde 2013, uma série de seminários abertos, coincidindo com os equinócios e os solstícios. Os libretos Materiais para o Fim do Mundo recolhem alguns ensaios apresentados nesses seminários, ou textos afins. Neste sexto libreto, David Pinho Barros relê A Estrela Misteriosa de Hergé (1942), interrogando a importância da perspectiva humana e sua escala (de que tamanho é uma aranha ou um cogumelo no fim do mundo?), com a Segunda Guerra Mundial como inevitável referência tácita; José Bértolo estuda os filmes do «ciclo bretão» de Jean Epstein - de Finis Terræ (1929) a Les Feux de la Mer (1948), analisando as linhas de fronteira entre terra, mar e céu, mundo natural e mundo humano, realidade e linguagem, literatura e cinema; e Luís Mendonça recorda um argumento de cinema escrito por James Agee em 1945, proposto a Charles Chaplin, mas nunca realizado: the tramp sobrevive a uma guerra nuclear de proporções apocalípticas, recusa o progresso científico que conduz afinal à morte da civilização, e parte, eternamente sozinho, pela estrada do crepúsculo

Calibração e validação de um modelo hidrológico para a bacia do rio Lima

O presente trabalho apresenta um modelo da bacia do Rio Lima, realçando-se os aspectos relacionados com a sua construção, calibração e validação. Este modelo será utilizado na simulação hidrológica daquela bacia integrado num trabalho de investigação com o objectivo de implementar um sistema de apoio à decisão para a gestão de cheias. Foi utilizada uma ferramenta de modelação hidrológica baseada no modelo de Sacramento (incluída no programa SOBEK), que funciona em simultâneo com um modelo hidrodinâmico. A calibração e validação do modelo hidrológico foram conseguidas utilizando dados históricos de caudais e níveis de água em Ponte da Barca e Ponte do Lima para diferentes eventos de precipitação e considerando a existência, ou não, do efeito da operação das barragens situadas a montante daquelas duas vilas. Procurou-se, desta forma, simular a hidrodinâmica do rio Lima quer em situações de escoamento normais quer durante a ocorrência de cheias, considerando os períodos anterior e posterior à construção das barragens do Alto Lindoso e de Touvedo. Os resultados obtidos demonstram elevada correlação com os parâmetros hidráulicos medidos (caudais e níveis de água)

Specification of a debureaucratization model in teaching: case study

Trabalho apresentado em ELEC 2018 – European Lean Educator Conference, 14-15 novembro 2018, Braga, PortugalNowadays data is crucial for any organization and its success depends on how it is managed. The management´s information process of the education system in general, and of an education institution, in particular, is a complex and bureaucratic process, where occurs information´s fragmentation. In order to counter this reality, people should be encouraged to simplify procedures by adopting a culture of continuous improvement. On the other hand, it is suggested an appropriate infrastructure that enables not only data integration but potentiates its transformation into knowledge. The data simplification and computerization will remove the bureaucracy associated with the management of processes, streamlining and translating them into the creation of value in the education sector. It should be noted, however, the importance of ensuring that the proposed solution is based on the needs and characteristics of each education institution, and the education system, in general. There is also the need for the involvement of all participants, as well as the recognition of their perceptions because these are influential factors in the successful implementation of the change process.N/

Analysis of self-interference within DAG tasks

6th Real-Time Scheduling Open Problems Seminar (RTSOPS 2015), Lund, Sweden.No abstract (2-pages paper) Few years ago, the frontier separating the real-time embedded domain from the high-performance computing domain was neat and clearly defined. Nowadays, many contemporary applications no longer find their place in either category as they manifest both strict timing constraints and work-intensive computational demands. The only way forward to cope with such orthogonal requirements is to embrace the parallel execution programming paradigm on the emergent scalable and energy-efficient multicore/many-core architecture

A Multi-DAG Model for Real-Time Parallel Applications with Conditional Execution

The 30th ACM/SIGAPP Symposium On Applied Computing (SAC 2015). 13 to 17, Apr, 2015, Embedded Systems. Salamanca, Spain.Owing to the current trends for higher performance and the ever growing availability of multiprocessors in the embedded computing (EC) domain, there is nowadays a strong push towards the parallelization of modern embedded applications. Several real-time task models have recently been proposed to capture different forms of parallelism. However, they do not deal explicitly with control flow information as they assume that all the threads of a parallel task must execute every time the task is activated. In contrast, in this paper, we present a multi-DAG model where each task is characterized by a set of execution flows, each of which represents a different execution path throughout the task code and is modeled as a DAG of sub-tasks. We propose a two-step solution that computes a single synchronous DAG of servers for a task modeled by a multi-DAG and show that these servers are able to supply every execution flow of that task with the required cpu-budget so that the task can execute entirely, irrespective of the execution flow taken at run-time, while satisfying its precedence constraints. As a result, each task can be modeled by its single DAG of servers, which facilitates in leveraging the existing single-DAG schedulability analyses techniques for analyzing the schedulability of parallel tasks with multiple execution flows

Coastal erosion: a northern-portuguese case study

Ponencia presentada en: XII Congreso de la Asociación Española de Climatología celebrado en Santiago de Compostela entre el 19 y el 21 de octubre de 2022.[EN]Coasts are socio-economically and ecologically highly important, yet vulnerable zones. Increasing pressure from human activities, like tourism, growing settlements and development of infrastructures, as well as climate change impacts, such as predicted sea-level rise and intensification of extreme climate, are likely to increase coastal vulnerability. Coastal Zone Management requires thus an evaluation of coastal dynamics, vulnerability and risks. The present work studied the morpho-sedimentary dynamics of the Northern-Portuguese Atlantic coast, between Caminha and Espinho. Digital terrain and surface models, derived from LiDAR and aerial photography survey data, collected in 2011, 2017 and 2018, were used to assess beach and dune morphology and to quantify morphodynamics. Coastal dynamics was analysed considering the types of beaches found in the region, being predominantly sandy beaches, sandy beaches with rocky outcrops, pebble and rocky beaches and dominant wind and wave conditions.[ES]Las áreas costeras son zonas de gran importancia socioeconómica y ecológica, pero a su vez son muy vulnerables. La vulnerabilidad de estas áreas puede aumentar con la creciente presión de las actividades humanas, como el turismo, el crecimiento de las zonas urbanas y el desarrollo de infraestructuras, así como con los impactos del cambio climático, como el aumento previsto del nivel del mar y la intensificación de extremos climáticos. Por lo tanto, es importante evaluar la vulnerabilidad y los riesgos para promover una gestión eficaz e integrada de las zonas costeras. El presente trabajo estudió los riesgos de erosión para la costa atlántica del norte de Portugal, entre Caminha y Espinho. Para evaluar la morfología de playas y dunas, y para cuantificar los procesos morfodinámicos, se utilizaron modelos digitales de terreno y de superficie, derivados de LiDAR y también datos de campañas de fotografía aérea, para los años 2011, 2017 y 2018. Se analizó la dinámica costera considerando los tipos de playas que se encuentran en la región, siendo predominantemente playas arenosas, playas arenosas con afloramientos rocosos, cantos rodados y playas rocosas, y también las condiciones predominantes de viento y oleaje.This research was partially supported by the Strategic Funding UIDB/04423/2020 and UIDP/04423/2020 through national funds provided by FCT—Foundation for Science and Technology and European Regional Development Fund (ERDF). This work was further funded by the European Union MarRISK project: Adaptación costera ante el Cambio Climático: conocer los riesgos y aumentar la resiliencia (0262_MarRISK_1_E), through EP INTERREG V A España-Portugal (POCTEP) program, and by the project EsCo-Ensembles (PTDC/ECI-EGC/30877/2017), co-financed by NORTE 2020, Portugal 2020 and the European Union through the ERDF, and by FCT through national funds

Towards a decision support system for flood management in a river basin

A platform for flood forecasting (FEWS-LIMA) in the Portuguese river Lima basin was implemented applying Delft-FEWS software. This platform integrates SOBEK Sacramento hydrological model, SOBEK rivers hydrodynamic models (working together in predicting river hydrodynamics behaviour), and a comprehensive hydrological database. The calibration of these models was achieved using historical river flow data of different rainfall events for two different periods: after the dams construction and before its construction. Models predictions use rainfall time series as input data obtained from Numerical Weather Prediction models. The performance of forecasting platform was verified in real rainfall events, using a backcasting approach for four flood events occurred in the years 2006, 2010, and 2011 in order to demonstrate the accuracy of the modelled processes. In addition, a forecasting event was also considered in order to show the applicability of this methodology in future situations. It was verified, in this case study, that the obtained results have a high correlation to the actually measured typical flood hydraulic parameters

On the Use of Thermal Properties for Characterizing Dimension Stones

The use of dimension stones in architecture and civil engineering implies the knowledge of several mechanical, physical, and chemical properties. Even though it has been usual practice to measure physical and mechanical properties of dimension stones the same is not true for thermal properties such as thermal conductivity, thermal diffusivity, specific heat capacity, and heat production. These properties are particularly important when processes related with heating and cooling of buildings must be considered. Thermal conductivity, thermal diffusivity, and specific heat capacity are related with the way thermal energy is transmitted and accumulated in stones; heat production has to do with the amount of radioactive elements in the rocks and so with the environmental impact of radioactivity and public health problems. It is important to start to measure on a routine basis those four thermal properties in rocks and, in particular, in dimension rocks so that their application can be improved and optimized. With this is mind three sets of different rock types (granites, limestones, and marbles) were collected to measure the thermal conductivity, the thermal diffusivity, and the specific heat capacity with the objective of characterizing them in terms of those properties. Since the same set of rocks has also been studied for other physical properties, a correlation amongst all the measured properties is attempted. For each rock type several samples were used to measure the thermal conductivity, the thermal diffusivity, and the specific heat capacity, and average values were obtained and are presented. As an example, for granites the thermal conductivity varies between 2.87 and 3.75 W/mK; for limestones varies between 2.82 and 3.17 W/mK; and for marbles varies between 2.86 and 3.02 W/mK. It is hoped that measuring thermal properties on dimension stones will help to better adequate them to their use in civil engineering as well as to adequate their use in terms of a CE product