Enabling system survival across hypervisor failures

Dissertação de mestrado em Engenharia Eletrónica Industrial e ComputadoresEmbedded system’s evolution is notorious and due to the complexity growth, these systems possess more general purpose behaviour instead of its original single purpose features. Naturally, virtualization started to impact this matter. This technology decreases the hardware costs since it allows to run several software components on the same hardware. Although virtualization begun as a pure software layer, many companies started to provide hardware solutions to assist it. Despite ARM TrustZone technology being a security extension, many developers realized that it was possible to use this extension to support development of hypervisors. With TrustZone, hypervisors can ensure one of the most important features in virtualization: isolation between guests. However, this hardware technology revealed some vulnerabilities and since the whole system is TrustZone dependent, the virtualization can be compromised. To address this problem, this thesis proposes an hybrid software/hardware mechanism to handle failures of TrustZone-based hypervisors. By using the processor’s abort exceptions and hash keys, this project detects system malfunctions caused by imperfect designs or even deliberate attacks. Additionally, it provides a restoration model by checkpoints which allows a system recovery without major throwbacks. The implemented solution was deployed on TrustZone-based LTZVisor, an open-source and in-house hypervisor, and the revealed results are appealing. With a 6.5% memory footprint increase and in the worst case scenario, an increment of 23% in context switching time, it is possible to detect secure memory invasions and recover the system. Despite of the hypervisor memory footprint increment and latency addition, the reliability and availability that the system bring to the LTZVisor are unquestionable.A evolução dos sistemas embebidos é notória e, devido ao aumento da sua complexidade, estes sistemas cada vez mais possuem um comportamento de propósito geral, em vez das suas características originais de propósito único. Naturalmente, a virtualização começou a ter impacto sobre este meio, uma vez que permite executar vários componentes de software no mesmo hardware, diminuindo os custos de hardware. Embora a virtualização tenha começado como uma camada de software pura, muitas empresas começaram a fornecer soluções de hardware para auxiliá-lo. Apesar da TrustZone ter sido projetada pela ARM para ser uma extensão de segurança, muitos desenvolvedores perceberam que era possível usá-la para suporte ao desenvolvimento de hipervisores. Com a TrustZone, os hipervisores podem garantir uma das premissas mais importantes da virtualização: isolamento entre hóspedes. No entanto, esta tecnologia de hardware revelou algumas vulnerabilidades e, sendo todo o sistema dependente da TrustZone, a virtualização pode ficar comprometida. Para solucionar o problema, esta tese propõe um mecanismo híbrido de software/ hardware para lidar com as falhas em hipervisores baseados em TrustZone. Usando as excepções do processador e chaves de hash, este projecto detecta defeitos no sistema causados por imperfeições no design e também ataques intencionais. Além disso, este fornece um modelo de restauração por pontos de verificação, permitindo uma recuperação do sistema sem grandes retrocessos. A solução foi implementada no LTZVisor, um hipervisor em código aberto e desenvolvido no ESRG, sendo que os resultados revelados são satisfatórios. Com um aumento de 6,5% da memória usada e um incremento, no pior caso, de 23% no tempo de troca de contexto, é possível detectar invasões de memória segura e recuperar o sistema. Apesar do incremento de memória do hypervisor e da adição de latência, a confiabilidade e a disponibilidade que o sistema oferece ao LTZVisor são inquestionáveis

Hardware-accelerated data decoding and reconstruction for automotive LiDAR sensors

The automotive industry is facing an unprecedented technological transformation towards fully autonomous vehicles. Optimists predict that, by 2030, cars will be sufficiently reliable, affordable, and common to displace most current human driving tasks. To cope with these trends, autonomous vehicles require reliable perception systems to hear and see all the surroundings, being light detection and ranging (LiDAR) sensors a key instrument for recreating a 3D visualization of the world. However, for a reliable operation, such systems require LiDAR sensors to provide high-resolution 3D representations of the car’s vicinity, which results in millions of data points to be processed in real-time. With this article we propose the ALFA-Pi, a data packet decoder and reconstruction system fully deployed on an embedded reconfigurable hardware platform. By resorting to field-programmable gate array (FPGA) technology, ALFAPi is able to interface different LiDAR sensors at the same time, while providing custom representation outputs to high-level perception systems. By accelerating the LiDAR interface, the proposed system outperforms current software-only approaches, achieving lower latency in the data acquisition and data decoding tasks while reaching high performance ratios

DIOR: a hardware-assisted weather denoising solution for LiDAR Point Clouds

The interest in developing and deploying fully autonomous vehicles on our public roads has come to a full swing. Driverless capabilities, widely spread in modern vehi cles through advanced driver-assistance systems (ADAS), require highly reliable perception features to navigate the environment, being light detection and ranging (LiDAR) sen sors a key instrument in detecting the distance and speed of nearby obstacles and in providing high-resolution 3D rep resentations of the surroundings in real-time. However, and despite being assumed as a game-changer in the autonomous driving paradigm, LiDAR sensors can be very sensitive to adverse weather conditions, which can severely affect the vehicle’s perception system behavior. Aiming at improving the LiDAR operation in challenging weather conditions, which contributes to achieving higher driving automation levels defined by the Society of Automotive Engineers (SAE), this article proposes a weather denoising method called Dynamic light-Intensity Outlier Removal (DIOR). DIOR combines two approaches of the state-of-the-art, the dynamic radius outlier removal (DROR) and the low-intensity outlier removal (LIOR) algorithms, supported by an embedded reconfigurable hardware platform. By resorting to field-programmable gate array (FPGA) technology, DIOR can outperform state-of-the-art outlier removal solutions, achieving better accuracy and performance while guaranteeing the real-time requirements.This work was supported by the Fundacao para a Ciencia e Tecnologia (FCT) within the Research and Development Units Project Scope under Grant UIDB/00319/2020

A multi-scale approach for particle-laden viscoelastic flows using a discrete particle method

Apresentação efetuada no 9th OpenFOAM Conference, em Worldwide, ONLINE, 2021[Excerpt] Accurately resolving the coupled momentum transfer between the liquid and solid phases is a fundamental problem in multiphase transport processes involving complex fluids, such as in hydraulic fracture operations. Specifically, we need to characterize the dependence of the normalized average fluid-particle force on the volume fraction of the dispersed solid phase and on the rheology of the complex fluid matrix, parameterized through the Weissenberg number Wi measuring the relative magnitude of elastic to viscous stresses in the fluid.This work is funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT (Portuguese Foundation for Science and Technology) under the projects UID-B/05256/2020, UID-P/05256/2020, APROVA-Aprendizagem PROfunda na modelação de escoamentos com fluidos de matriz Viscoelástica Aditivados com partículas (POCI-01-0145- FEDER-016665). The authors would like to acknowledge the Minho University cluster under the project NORTE-07-0162-FEDER-000086 (URL: http://search6.di.uminho.pt), the Minho Advanced Computing Center (MACC) (URL: https://macc.fccn.pt), the Texas Advanced Computing Center (TACC) at The University of Texas at Austin (URL: http://www.tacc.utexas.edu) and the Gompute HPC Cloud Platform (URL: https://www.gompute.com) for providing HPC resources that have contributed to the research results reported within this paper

Fast computational processing for mobile robots' self-localization

This paper intends to present a different approach to solve the Self-Localization problem regarding a RoboCup’s Middle Size League game, developed by MINHO team researchers. The method uses white field markings as key points, to compute the position with least error, creating an error-based graphic where the minimum corresponds to the real position, that are computed by comparing the key (line) points with a precomputed set of values for each position. This approach allows a very fast local and global localization calculation, allowing the global localization to be used more often, while driving the estimate to its real value. Differently from the majority of other teams in this league, it was important to come up with a new and improved method to solve the traditional slow Self-Localization problem.This work was developed at the Laboratório de Automação e Robótica by MINHO team´s researching and developing team, at University of Minho, under the supervision of Professor A. Fernando Ribeiro and A. Gil Lopes. The knowledge exchanging between the RoboCup’s MSL teams and community contributed greatly for the development of this work. This work has been supported by COMPETE: POCI-01- 0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013.info:eu-repo/semantics/publishedVersio

Motion control of mobile autonomous robots using non-linear dynamical systems approach

This paper presents a solution to the problem of motion control of an autonomous robot, moving in a dynamical and unstable environment. It is based on non-linear dynamical systems, modelling the state variables that define the motion of a robot under an omnidirectional platform, like its direction of navigation and velocity. The approach used, is based on a set of non-linear differential equations that model the evolution of state variables along time, based on the concept of attractors and repellers. In the official RoboCup Middle Size League field, a target is used to attract the robot to a certain position (could be the ball or a desired position to receive the ball), while a repeller could move the robot away from its original path (given by obstacles in the surrounding environment). The research was firstly carried out in a computational simulation environment and later on with robots in a real environmentThis work was developed at the Automation and Robotics Laboratory by MINHO R&D TEAM, University of Minho, under the supervision of Professor A. Fernando Ribeiro and A. Gil Lopes. The knowledge exchanging between the RoboCup’s MSL teams and community contributed greatly for the development of this work. This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013.info:eu-repo/semantics/publishedVersio

Prevalence and pattern of cognitive impairment in rural and urban populations from Northern Portugal

<p>Abstract</p> <p>Background</p> <p>Despite worldwide recognition of the burden of dementia, no epidemiological data is yet available in Portugal. The objective of this study is to estimate the prevalence and describe the pattern of cognitive impairment with dementia or no dementia (CIND) in rural and urban populations from Northern Portugal.</p> <p>Methods</p> <p>Two random samples of residents aged 55 to 79 years in rural and urban communities were drawn from the health centres registries to be screened for cognitive impairment. The screening criteria for dementia were an abnormal Mini-Mental State Examination (MMSE) score or a Blessed Dementia Scale score. After excluding those who tested positive for dementia, cut-off points for CIND were set at 1 standard deviation below the mean of the MMSE according to educational level. All those who screened positive either for dementia or CIND were examined by a neurologist for establishing a definitive diagnosis.</p> <p>Results</p> <p>The prevalence of cognitive impairment was higher in rural than in urban populations, 16.8% (95% CI: 14.3-19.8%) vs. 12.0% (95%CI: 9.3-15.4%), with a rural/urban prevalence ratio (PR) of 2.16 (95% CI: 1.04-4.50) in the eldest and 2.19 (95% CI: 1.01-4.76) in persons with vascular risk factors. The prevalence of dementia was 2.7% (95% CI: 1.9-3.8%) with a rural/urban PR = 2.1 and the prevalence of CIND was 12.3% (95% CI: 10.4-14.4%) and PR = 1.3. The prevalence of dementia increases exponentially with age and in those with cerebrovascular disease or other comorbid conditions while the prevalence of CIND, besides these factors, is also higher in persons with low levels of education or vascular risk factors. Alzheimer's and vascular disease were equally likely aetiologies of dementia (38.7%), the later more common in men PR(F:M = 0.3) as opposed to the former PR(F:M = 2.0). Vascular CIND, associated either with cerebrovascular disease or vascular risk factors was more frequent (39.7%) then depression (18.4%) or any other aetiology.</p> <p>Conclusions</p> <p>The prevalence of cognitive impairment is higher in rural compared with urban populations. This is shown in the synergy between age and rurality, with the rural/urban prevalence ratio increasing with age. In this relatively young population from Northern Portugal, cerebrovascular disease as well as vascular risk factors account for 48% of overall cognitive impairment.</p

Evaluation and testing system for automotive LiDAR sensors

The world is facing a great technological transformation towards fully autonomous vehicles, where optimists predict that by 2030 autonomous vehicles will be sufficiently reliable, affordable, and common to displace most human driving. To cope with these trends, reliable perception systems must enable vehicles to hear and see all their surroundings, with light detection and ranging (LiDAR) sensors being a key instrument for recreating a 3D visualization of the world in real time. However, perception systems must rely on accurate measurements of the environment. Thus, these intelligent sensors must be calibrated and benchmarked before being placed on the market or assembled in a car. This article presents an Evaluation and Testing Platform for Automotive LiDAR sensors, with the main goal of testing both commercially available sensors and new sensor prototypes currently under development in Bosch Car Multimedia Portugal. The testing system can benchmark any LiDAR sensor under different conditions, recreating the expected driving environment in which such devices normally operate. To characterize and validate the sensor under test, the platform evaluates several parameters, such as the field of view (FoV), angular resolution, sensor’s range, etc., based only on the point cloud output. This project is the result of a partnership between the University of Minho and Bosch Car Multimedia Portugal.This work was supported by the European Structural and Investment Funds in the FEDER component through the Operational Competitiveness and Internationalization Programme (COM-PETE 2020), Project nº 037902, Funding Reference POCI-01-0247-FEDER-037902

Inatividade física no lazer e na escola está associada à presença de transtornos mentais comuns na adolescência

OBJECTIVE: To investigate the association of physical inactivity in leisure and school time with common mental disorders during adolescence. METHODS: The sample consisted of 73,399 adolescents (12–17 years old), participants in the Estudo de Riscos Cardiovasculares em Adolescentes (Erica — Study of Cardiovascular Risks in Adolescents). This cross-sectional, national and school-based study was conducted in 2013 and 2014 in Brazilian municipalities with more than 100,000 inhabitants. Leisure time physical activity was categorized according to weekly practice volume, and adolescents were classified as active (≥ 300 minutes/week), inactive (0 minute/week) and insufficiently active (1–299 minutes/week). Sports practice and participation in physical education classes at school were also analyzed. The presence of common mental disorders was assessed based on the general health questionnaire, with a cutoff point greater than or equal to 3. Odds ratios (OR) were estimated using multiple logistic regression. RESULTS: The chance of common mental disorders was 16% higher in the group that reported being inactive (0 minute/week) at leisure time (OR = 1.16; 95%CI 1.06 (1.27). The prevalence of common mental disorders was higher among young people who did not practice sports (37.2% vs. 25.9%; OR = 1.14; 95%CI 1.04–1.25) and did not participate in physical education classes at school (39.5% vs. 29.6%; OR = 1.25; 95%CI 1.15–1.36). Insufficient physical activity (1–299 minutes/week) did not increase the OR of common mental disorders. Practicing physical activity during leisure time, regardless of duration and weekly frequency, reduced the chances of common mental disorders in this population by 26%. CONCLUSIONS: Physical inactivity during leisure and school time is associated with the presence of common mental disorders in adolescence. The results suggest that sports practice, school physical education and physical activity during leisure time, even without reaching the current recommendation, are related to the mental health of young people.OBJETIVO: Investigar a associação da inatividade física no lazer e na escola com os transtornos mentais comuns durante a adolescência. MÉTODOS: A amostra foi composta por 73.399 adolescentes (12–17 anos), participantes do Estudo de Riscos Cardiovasculares em Adolescentes (Erica). Esse estudo transversal, nacional e de base escolar foi realizado em 2013 e 2014, nos municípios brasileiros com mais de 100 mil habitantes. A atividade física no lazer foi categorizada de acordo com o volume de prática semanal, e os adolescentes foram classificados em ativos (≥ 300 minutos/semana), inativos (0 minuto/semana) e insuficientemente ativos (1–299 minutos/semana). A prática esportiva e a participação em aulas de educação física na escola também foram analisadas. A presença de transtornos mentais comuns foi avaliada a partir do general health questionnaire, com ponto de corte maior ou igual a 3. Odds ratios (OR) foram estimados utilizando regressão logística múltipla. RESULTADOS: A chance de transtornos mentais comuns foi 16% maior no grupo que relatou ser inativo (0 minuto/semana) no lazer (OR = 1,16; IC95% 1,06–1,27). A prevalência de transtornos mentais comuns foi maior entre jovens que não praticaram esportes (37,2% vs. 25,9%; OR = 1,14; IC95% 1,04–1,25) e não participaram das aulas de educação física na escola (39,5% vs. 29,6%; OR = 1,25; IC95% 1,15–1,36). Atividade física insuficiente (1–299 minutos/semana) não aumentou a razão de chances de transtornos mentais comuns. Praticar atividade física no lazer, independentemente da duração e frequência semanal, reduziu em 26% as chances de transtornos mentais comuns nessa população. CONCLUSÕES: A inatividade física no lazer e na escola foi associada à presença de transtornos mentais comuns na adolescência. Os resultados sugerem que prática esportiva, educação física escolar e atividade física durante o lazer, mesmo sem atingir a recomendação atual, têm relação com a saúde mental dos jovens

Chemical features and bioactivities of cornflower (Centaurea cyanus L.) capitula: The blue flowers and the unexplored non-edible part

Cornflower is a flowering weed and ornamental plant whose blue flowers have been used for food, decorative and colouring purposes. In this study, the upper (edible flowers) and lower (non-edible receptacle and involucre) parts of the capitulum were studied and compared for their chemical composition and bioactive properties. The flowers were richer in tocopherols, organic acids, and apigenin derivatives (mainly apigenin-7-O-glucuronide-4′-O-(6-O-malonylglucoside)) than the non-edible bristly part (where syringic acid predominated). Four cyanidin derivatives were identified in the flowers. The extract of the non-edible part was more efficient in inhibiting the formation of thiobarbituric acid reactive substances (TBARS), the bleaching of β-carotene, and the haemolysis of the erythrocytes membrane. In general, the extracts were more active against Gram-positive bacteria and had no cytotoxicity against non-tumour liver PLP2 cells. Therefore, while flowers are a potential source of natural cyanidin-based colorants, the lower part of the capitulum has bioactive properties to be exploited in different food or pharmaceutical formulations.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO ( UID/AGR/00690/2013 ); to FCT for the grants of C.L. Roriz ( SFRH/BD/129551/2017 ) and C. Pereira ( SFRH/BPD/122650/2016 ) (awarded under the Programa Operacional Capital Humano (POCH) supported by the European Social Fund and National Funds of MCTES (Ministério da Ciência, Tecnologia e Ensino Superior) , and the research contracts of J. Pinela (Project AllNatt , POCI-01-0145-FEDER-030463 ) and L. Barros. This work is also funded by the European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of Project NORTE-01-0145-FEDER-023289: DeCodE and project Mobilizador Norte-01-0247-FEDER-024479: ValorNatural®; and FEDER-Interreg España-Portugal through the project 0377_Iberphenol_6_E.info:eu-repo/semantics/publishedVersio