8 research outputs found

    Analysis and identification of possible automation approaches for embedded systems design flows

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    Sophisticated and high performance embedded systems are present in an increasing number of application domains. In this context, formal-based design methods have been studied to make the development process robust and scalable. Models of computation (MoC) allows the modeling of an application at a high abstraction level by using a formal base. This enables analysis before the application moves to the implementation phase. Different tools and frameworks supporting MoCs have been developed. Some of them can simulate the models and also verify their functionality and feasibility before the next design steps. In view of this, we present a novel method for analysis and identification of possible automation approaches applicable to embedded systems design flow supported by formal models of computation. A comprehensive case study shows the potential and applicability of our method11212

    Nonlinear control techniques for the trajectory tracking problem applied to quadrotors

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    Orientador: Juan Francisco CaminoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecânicaResumo: O projeto de controladores voltado ao problema de rastreamento de trajetórias para quadricópteros é uma tarefa complexa pois requer a aplicação de técnicas avançadas de controle, já que o modelo dinâmico do quadricóptero é não linear e subatuado. Em situações reais, um quadricóptero está sujeito a vários tipos de perturbações que podem prejudicar o desempenho dos controladores projetados. Este trabalho apresenta projetos de controladores de rastreamento de trajetórias para um quadricóptero sujeito a perturbações em sua dinâmica de voo. A arquitetura do sistema de controle é constituída de uma malha interna de controle contendo um controlador por \textit{feedback linearization}, que será responsável por neutralizar as não linearidades presentes no modelo dinâmico e lidar com a subatuação inerente do sistema, e uma malha externa de controle. Para a malha externa, que é responsável pela estabilidade e rejeição às perturbações, são apresentados três projetos de controladores: um controlador LQR, um controlador Hoo e um controlador por sliding mode. Simulações numéricas são apresentadas para demonstrar a capacidade de rastreamento de trajetórias e a rejeição a perturbações de cada um dos três projetos propostosAbstract: Designing trajectory tracking controllers for quadrotors is not a trivial task. Since the quadrotor's dynamic model is nonlinear and underactuated, the use of advanced control techniques is often required. In real applications, a quadrotor is subject to different kinds of disturbances that can affect the performance of the designed controllers. This work presents different trajectory tracking controller designs for a quadrotor with disturbances in its flight dynamics. The control system architecture is composed of an inner and an outer control loop. The inner loop, created through feedback linearization, counteracts nonlinearities of the dynamic model while dealing with the underactuation of the system. For the outer loop, responsible for stability and disturbance rejection, three different control designs are presented: one LQR controller, one Hoo controller and one sliding mode controller. Numerical simulations show the trajectory tracking performance and disturbance rejection capabilities of the proposed controllersMestradoMecanica dos Sólidos e Projeto MecanicoMestre em Engenharia Mecânica33003017CAPE

    Modeling and simulation of dynamic applications using scenario-aware dataflow

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    The tradeoff between analyzability and expressiveness is a key factor when choosing a suitable dataflow model of computation (MoC) for designing, modeling, and simulating applications considering a formal base. A large number of techniques and analysis tools exist for static dataflow models, such as synchronous dataflow. However, they cannot express the dynamic behavior required for more dynamic applications in signal streaming or to model runtime reconfigurable systems. On the other hand, dynamic dataflow models like Kahn process networks sacrifice analyzability for expressiveness. Scenario-aware dataflow (SADF) is an excellent tradeoff providing sufficient expressiveness for dynamic systems, while still giving access to powerful analysis methods. In spite of an increasing interest in SADF methods, there is a lack of formally-defined functional models for describing and simulating SADF systems. This article overcomes the current situation by introducing a functional model for the SADF MoC, as well as a set of abstract operations for simulating it. We present the first modeling and simulation tool for SADF so far, implemented as an open source library in the functional framework ForSyDe. We demonstrate the capabilities of the functional model through a comprehensive tutorial-style example of a RISC processor described as an SADF application, and a traditional streaming application where we model an MPEG-4 simple profile decoder. We also present a couple of alternative approaches for functionally modeling SADF on different languages and paradigms. One of such approaches is used in a performance comparison with our functional model using the MPEG-4 simple profile decoder as a test case. As a result, our proposed model presented a good tradeoff between execution time and implementation succinctness. Finally, we discuss the potential of our formal model as a frontend for formal system design flows regarding dynamic applications245This research work was supported by the Swedish-Brazilian Research and Innovation Centre (CISB) and by Saab AB through the Call of Projects CISB Saab 04/2016

    Perfil hematológico de morcegos frugívoros, Artibeus lituratus (Chiroptera: Phyllostomidae)

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    It was provide a hematological profile of Artibeus lituratus (Phyllostomidae: Stenodermatinae). Animals were collected from October 2017 to February 2018 in an urban forest in the city of Rio de Janeiro, Southeastern Brazil. Males and females showed similar overall mean values for the parameters analyzed. Males had higher values for erythrocytes (RBC), hematocrit and basophils. Females had higher levels of eosinophils than males. The hematological values reported here will serve as reference for future research on health conditions of free-living and captive populations of Artibeus lituratus, as well as for research on pathogens associated with these bats.O presente trabalho estabeleceu o perfil hematológico de morcegos frugívoros de vida livre, A. lituratus (Phyllostomidae: Stenodermatinae). As amostragens foram realizadas de outubro de 2017 a fevereiro de 2018 em uma floresta urbana na cidade do Rio de Janeiro, Sudeste do Brasil. Machos e fêmeas apresentaram valores médios gerais semelhantes para os parâmetros analisados. Os machos apresentaram valores de eritrócitos (RBC), hematócrito e basófilos mais altos. As fêmeas apresentaram níveis mais elevados de eosinófilos que os machos. Os valores hematológicos aqui reportados servirão de referência para pesquisas sobre condições de saúde de populações de Artibeus lituratus em vida livre e de cativeiro, assim como para pesquisas sobre patógenos associados a esses morcegos

    Impact of the COVID-19 pandemic on patients with paediatric cancer in low-income, middle-income and high-income countries: a multicentre, international, observational cohort study

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    OBJECTIVES: Paediatric cancer is a leading cause of death for children. Children in low-income and middle-income countries (LMICs) were four times more likely to die than children in high-income countries (HICs). This study aimed to test the hypothesis that the COVID-19 pandemic had affected the delivery of healthcare services worldwide, and exacerbated the disparity in paediatric cancer outcomes between LMICs and HICs. DESIGN: A multicentre, international, collaborative cohort study. SETTING: 91 hospitals and cancer centres in 39 countries providing cancer treatment to paediatric patients between March and December 2020. PARTICIPANTS: Patients were included if they were under the age of 18 years, and newly diagnosed with or undergoing active cancer treatment for Acute lymphoblastic leukaemia, non-Hodgkin's lymphoma, Hodgkin lymphoma, Wilms' tumour, sarcoma, retinoblastoma, gliomas, medulloblastomas or neuroblastomas, in keeping with the WHO Global Initiative for Childhood Cancer. MAIN OUTCOME MEASURE: All-cause mortality at 30 days and 90 days. RESULTS: 1660 patients were recruited. 219 children had changes to their treatment due to the pandemic. Patients in LMICs were primarily affected (n=182/219, 83.1%). Relative to patients with paediatric cancer in HICs, patients with paediatric cancer in LMICs had 12.1 (95% CI 2.93 to 50.3) and 7.9 (95% CI 3.2 to 19.7) times the odds of death at 30 days and 90 days, respectively, after presentation during the COVID-19 pandemic (p<0.001). After adjusting for confounders, patients with paediatric cancer in LMICs had 15.6 (95% CI 3.7 to 65.8) times the odds of death at 30 days (p<0.001). CONCLUSIONS: The COVID-19 pandemic has affected paediatric oncology service provision. It has disproportionately affected patients in LMICs, highlighting and compounding existing disparities in healthcare systems globally that need addressing urgently. However, many patients with paediatric cancer continued to receive their normal standard of care. This speaks to the adaptability and resilience of healthcare systems and healthcare workers globally

    Twelve-month observational study of children with cancer in 41 countries during the COVID-19 pandemic

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    Childhood cancer is a leading cause of death. It is unclear whether the COVID-19 pandemic has impacted childhood cancer mortality. In this study, we aimed to establish all-cause mortality rates for childhood cancers during the COVID-19 pandemic and determine the factors associated with mortality
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