Polytechnic Institute of Porto
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Mixed Criticality Scheduling of Probabilistic Real-Time Systems
No full textIn this paper we approach the problem of Mixed Criticality (MC) for probabilistic real-time systems where tasks execution times are described with probabilistic distributions. In our analysis, the task enters high criticality mode if its response time exceeds a certain threshold, which is a slight deviation from a more classical approach in MC. We do this to obtain an application oriented MC system in which criticality mode changes depend on actual scheduled execution. This is in contrast to classical approaches which use task execution time to make criticality mode decisions, because execution time is not affected by scheduling while the response time is. We use a graph-based approach to seek for an optimal MC schedule by exploring every possible MC schedule the task set can have. The schedule we obtain minimizes the probability of the system entering high criticality mode. In turn, this aims at maximizing the resource efficiency by the means of scheduling without compromising the execution of the high criticality tasks and minimizing the loss of lower criticality functionality. The proposed approach is applied to test cases for validation purposes.info:eu-repo/semantics/publishedVersio
Automated sheep facial expression classification using deep transfer learning
No full textDigital image recognition has been used in the different aspects of life, mostly in object classification and detections. Monitoring of animal life with image recognition in natural habitats is essential for animal health and production. Currently, Sheep Pain Facial Expression Scale (SPFES) has become the focus of monitoring sheep from facial expression. In contrast, pain level estimation from facial expression is an efficient and reliable mark of animal life. However, the manual assessment is lack of accuracy, time-consuming, and monotonous. Hence, the recent advancement of deep learning in computer vision helps to classify facial expression as fast and accurate. In this paper, we proposed a sheep face dataset and framework that uses transfer learning with fine-tuning for automating the classification of normal (no pain) and abnormal (pain) sheep face images. Current state-of-the-art convolutional neural networks (CNN) based architectures are used to train the sheep face dataset. The data augmentation, L2 regularization, and fine-tuning has been used to prepare the models. The experimental results related to the sheep facial expression dataset achieved 100% training, 99.69% validation, and 100% testing accuracy using the VGG16 model. While employing other pre-trained models, we gained 93.10% to 98.4% accuracy. Thus, it shows that our proposed model is optimal for high-precision classification of normal and abnormal sheep faces and can check on a comprehensive dataset. It can also be used to assist other animal life with high accuracy, save time and expenses.info:eu-repo/semantics/publishedVersio
Wood Connections Under Fire Conditions Protected with Gypsum Plasterboard Types A and F
No full textThe wood behavior varies with temperature, which has a negative effect, be-ing verified by progressive properties degradation. After fire exposure, it is possible to measure the wood char layer and the remaining resistant cross-section area. Based on numerical models and analytical equations, it is pos-sible to study the protection level of wood connections, during fire exposure, and evaluate wood and steel dowels temperature fields in conjunction. The main objective of this work is to verify the fire resistance of unprotected (W-W-W) wood connections and compare the results with protected connections using gypsum plasterboard. According Eurocode 5, part 1-2 the connections could be protected by the addition of wood paneling, wood-based panels or gypsum plasterboard type A, H or F. To obtain conclusions according the application of different type of gypsum plasterboard in the designed W-W-W connections in different densities material, numerical models were building to verify the level of protection in fire action. Design methods require the use of analytical methodologies and computational modelling to predict the fire exposure and the components capacity to resist to this action. Results of the temperature field in the studied connections under fire will be presented, with the measured char layer in unprotected members and comparing the protected efficiency with different types of gypsum plasterboard.info:eu-repo/semantics/publishedVersio
Response time analysis of multiframe mixed-criticality systems
No full textOutstanding paper awardRTNS '19: Proceedings of the 27th International Conference on Real-Time Networks and Systems - November 2019The well-known model of Vestal aims to avoid excessive pessimism
in the quantification of the processing requirements of mixedcriticality systems, while still guaranteeing the timeliness of highercriticality functions. This can bring important savings in system
costs, and indirectly help meet size, weight and power constraints.
This efficiency is promoted via the use of multiple worst-case execution time (WCET) estimates for the same task, with each such
estimate characterised by a confidence associated with a different criticality level. However, even this approach can be very pessimistic when the WCET of successive instances of the same task
can vary greatly according to a known pattern, as in MP3 and MPEG
codecs or the processing of ADVB video streams.
In this paper, we present a schedulability analysis for the multiframe mixed-criticality model, which allows tasks to have multiple, periodically repeating, WCETs in the same mode of operation. Our work extends both the analysis techniques for Static
Mixed-Cricality scheduling (SMC) and Adaptive Mixed-Criticality
scheduling (AMC), on one hand, and the schedulability analysis
for multiframe task systems on the other. Our proposed worst-case
response time (WCRT) analysis for multiframe mixed-criticality
systems is considerably less pessimistic than applying the SMC,
AMC-rtb and AMC-max tests obliviously to the WCET variation
patterns. Experimental evaluation with synthetic task sets demonstrates up to 63.8% higher scheduling success ratio (in absolute
terms) compared to the best of the frame-oblivious testsinfo:eu-repo/semantics/publishedVersio
Comparing the Ecological Footprint of Intersection Management Protocols for Human/Autonomous Scenarios
No full textThe design of Intelligent Intersection Management (IIM) schemes for fully Autonomous Vehicles (AVs) and mixed with Human-driven Vehicles (HVs) has focused mainly on throughput maximization and users’ safety. However, new IIM strategies should consider environmental factors and human health conditions in their design, given their impact on fuel wastage and emission of dangerous air pollutants. In this paper, we compare the ecological footprint of two IMM protocols that follow opposite paradigms in handling AVs and HVs with an internal combustion engine. We consider Round-Robin (RR) that favors the crossing of multiple consecutive cars from one road at a time and the recently proposed Synchronous Intersection Management Protocol (SIMP) that favors the crossing of multiple cars simultaneously, one from each road. Through experiments in the SUMO simulator, we observe that SIMP promotes more fluid traffic flows, causing traffic throughput to be up to 3.7 times faster and consume less fuel than the RR schemes, with similar results for vehicular emissions (PMx, NOx, CO, CO 2 , and HC).info:eu-repo/semantics/publishedVersio
Measuring optical properties of human liver between 400 and 1000 nm
No full textLaser diagnostics and treatment procedures are commonly performed for visible and near-IR wavelengths. The knowledge of the wavelength dependences for the optical properties of various biological tissues in this spectral range is useful for clinical applications. Since the optical properties of human liver have been previously known only for near-IR wavelengths, the aim is to estimate their wavelength dependences between 400 and 1000 nm. Using spectral measurements from liver samples in this range, we determine their optical properties with the inverse adding-doubling method. The obtained results indicate the presence of bile, oxyhaemoglobin and deoxyhaemoglobin in human liver. The combination of these biological components results in strong absorption for wavelengths between 400 and 600 nm, with peaks at unusual wavelengths. For wavelengths above 600 nm, the wavelength dependences for all optical properties present the typical behavior, but strong and shifted absorption observed for wavelengths below 600 nm has been previously unknown and can be useful for clinical procedures with lasers working in this range.This research was supported by the Portuguese research grant UID-EQU-04730-2013. Work of VVT was supported by the Russian Foundation for Basic Research (Grant No. 17-00-00275 (17-00-00272)].info:eu-repo/semantics/publishedVersio
Metal(loid) oxide (Al2O3, Mn3O4, SiO2 and SnO2) nanoparticles cause cytotoxicity in yeast via intracellular generation of reactive oxygen species
No full textIn this work, the physicochemical characterization of five (Al2O3, In2O3, Mn3O4, SiO2 and SnO2) nanoparticles (NPs) was carried out. In addition, the evaluation of the possible toxic impacts of these NPs and the respective modes of action were performed using the yeast Saccharomyces cerevisiae. In general, in aqueous suspension, metal(loid) oxide (MOx) NPs displayed an overall negative charge and agglomerated; these NPs were practically insoluble (dissolution < 8%) and did not generate detectable amounts of reactive oxygen species (ROS) under abiotic conditions. Except In2O3 NPs, which did not induce an obvious toxic effect on yeast cells (up to 100 mg/L), the other NPs induced a loss of cell viability in a dose-dependent manner. The comparative analysis of the loss of cell viability induced by the NPs with the ions released by NPs (NPs supernatant) suggested that SiO2 toxicity was mainly caused by the NPs themselves, Al2O3 and SnO2 toxic effects could be attributed to both the NPs and the respective released ions and Mn3O4 harmfulness could be mainly due to the released ions. Al2O3, Mn3O4, SiO2 and SnO2 NPs induced the loss of metabolic activity and the generation of intracellular ROS without permeabilization of plasma membrane. The co-incubation of yeast cells with MOx NPs and a free radical scavenger (ascorbic acid) quenched intracellular ROS and significantly restored cell viability and metabolic activity. These results evidenced that the intracellular generation of ROS constituted the main cause of the cytotoxicity exhibited by yeasts treated with the MOx NPs. This study highlights the importance of a ROS-mediated mechanism in the toxicity induced by MOx NPs.This work was performed in the framework of the financing by Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020—Programa Operacional Regional do Norte and LAQV (UID/QUI/50006/2019) with funding from FCT/MCTES through national funds.info:eu-repo/semantics/publishedVersio
Bounding Cache Persistence Reload Overheads for Set-Associative Caches
No full textCache memories have a strong impact on the response time of tasks executed on modern computing platforms. For tasks scheduled under fixed-priority preemptive scheduling (FPPS), the worst-case response time (WCRT) analyses that account for cache persistence between jobs along with cache related preemption delays (CRPDs) have been shown to dominate analyses that only consider CRPDs. Yet, the existing approaches that analyze cache persistence in the context of WCRT analysis can only support direct-mapped caches. In this work, we analyze cache persistence in the context of WCRT analysis for set-associative caches. The main contributions of this work are: (i) to propose a solution to find persistent cache blocks (PCBs) of tasks considering set-associative caches, (ii) to present three different approaches to calculate cache persistence reload overheads (CPROs), i.e., the memory overhead due to eviction of PCBs of tasks, under set-associative caches, and (iii) an experimental evaluation showing that our proposed approaches result in up to 22 percentage points higher task set schedulability than the state-of-the-art approaches.info:eu-repo/semantics/publishedVersio
Transportation Policy Evaluation Using Minority Games and Agent-Based Simulation
No full textTraffic congestion is an issue regarding the vitality of cities and the welfare of citizens. Transportation systems are using various technologies to allow users to adapt and make different decisions towards transportation modes. Modification and improvement of these systems affect the commuters' perspective and social welfare. In this study, the effect of road flow equilibrium on commuters' utilities with different types of transportation modes will be discussed. A simple network with two modes of transportation will be illustrated and three different cost policies were considered to test the efficiency of reinforcement learning in commuters' daily trip decision-making regarding time and mode. The artificial society of agents is simulated to analyse the results.info:eu-repo/semantics/publishedVersio
HopliteRT*: Real-Time NoC for FPGA
No full textThis article was presented in part at the International Conference on Embedded Software 2020 and appears as part of the ESWEEK-TCAD special issue.With the increasing number of computation nodes integrated in multi and many-core platforms, network-on-chips (NoCs) emerged as a new communication medium in systems-on-chips (SoCs). HopliteRT is a new NoC design that was recently proposed to address the needs of real-time systems whilst respecting the constraints of field-programmable gate array (FPGA) platforms. In this article, we: 1) introduce priority-based routing in HopliteRT; 2) change the network topology in order to improve the packets’ worst-case traversal time (WCTT); 3) identify a flaw in the existing timing analysis of HopliteRT; and 4) develop a new timing analysis that is proven correct. We also show by means of experiments that the modifications of HopliteRT proposed in this article allows for at least 2× improvement on the worst and average case traversal time of high priority packets, without impacting the quality of service of low-priority packets. The timing properties of high priority flows are greatly improved for negligible additional hardware costs. The proposed NoC has been implemented in Verilog and synthesized for a Xilinx Virtex-7 FPGA platform.info:eu-repo/semantics/publishedVersio