13 research outputs found

    Traffic Light Control Using Deep Policy-Gradient and Value-Function Based Reinforcement Learning

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    Recent advances in combining deep neural network architectures with reinforcement learning techniques have shown promising potential results in solving complex control problems with high dimensional state and action spaces. Inspired by these successes, in this paper, we build two kinds of reinforcement learning algorithms: deep policy-gradient and value-function based agents which can predict the best possible traffic signal for a traffic intersection. At each time step, these adaptive traffic light control agents receive a snapshot of the current state of a graphical traffic simulator and produce control signals. The policy-gradient based agent maps its observation directly to the control signal, however the value-function based agent first estimates values for all legal control signals. The agent then selects the optimal control action with the highest value. Our methods show promising results in a traffic network simulated in the SUMO traffic simulator, without suffering from instability issues during the training process

    Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

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    BackgroundDisorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.MethodsWe estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.FindingsGlobally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.InterpretationAs the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed

    The effect of gabapentin on muscle cramps during hemodialysis: A double-blind clinical trial

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    Hemodialysis‐associated muscle cramps (HAMC) are a common complication during hemodialysis (HD) sessions. A number of pharmacologic agents have been evaluated to prevent and or diminish HAMC; however, none of them has an established role. To the best of our knowledge, this is the first study to evaluate the possible effect of gabapentin on HAMC. In a double-blinded clinical trial, we compared the possible effect of gabapentin with a placebo in prevention and or diminishing episodes of HAMC in HD patients who had experienced frequent intradialytic muscle cramps. At first, placebo was given before each dialysis session for four weeks and then, after a two-week washout period, 300 mg of gabapentin was given before each dialysis session for four weeks to verify the effect of gabapentin on HAMC. Overall, 15 patients (seven men and eight women; mean age, 52.02 years) with frequent intradialytic muscle cramps were enrolled in the study. The incidence of symptomatic muscle cramp decreased in the gabapentin group compared with the placebo group, with a significant difference between them (P = 0.001). The intensity of muscle cramps also decreased in the gabapentin group (P = 0.001). There was no significant association between HAMC in male and female patients (P = 0. 397), mean age of HD patients (P = 0.226) and cause of end-stage renal disease (P = 0.551). According to the results of our study, gabapentin prescription before each HD session significantly reduced the frequency and the intensity of muscle cramps during HD without any major side-effects

    What are the Antecedents of Safety Performance in the Workplace?

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    Given the progressive growth of interest in both academic and practitioners about safety performance in the workplace, the aim of this study is to provide a review of the literature on workplace safety from the perspective of the antecedent of safety performance. By conducting a systematic literature review, a list of relevant contributions on workplace safety is provided. The contributions were analyzed and classified regarding the arguments about the antecedents of safety performance. The study integrated different domains of the antecedent of safety performance to provide a clear and consistent definition for the concept of antecedent when applied to safety performance. Moreover, a list of common antecedents of safety performance was extracted from the literature and categorized. Finally, a unified and classified framework for antecedents of safety performance is proposed. From an academic perspective, this paper enables future research in developing research streams on the antecedents of safety performance. Equally important, practitioners can employ the proposed framework to select leading KPIs for safety performance evaluation and monitoring in the workplace

    Improving pulse eddy current and ultrasonic testing stress measurement accuracy using neural network data fusion

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    Stress and residual stress are two crucial factors which play important roles in mechanical performance of materials, including fatigue and creep, hence measuring them is highly in demand. Pulse eddy current (PEC) and ultrasonic testing (UT) are two non-destructive tests (NDT) which are nominated to measure stresses and residual stresses by numerous scholars. However, both techniques suffer from lack of accuracy and reliability. One technique to tackle these challenges is data fusion, which has numerous approaches. This study introduces a promising one called neural network data fusion, which shows effective performance. First, stresses are simulated in an aluminium alloy 2024 specimen and then PEC and UT signals related to stresses are acquired and processed. Afterward, useful information obtained is fused using artificial neural network procedure and stresses are estimated by fused data. Finally, the accuracy of fused data are compared with PEC and UT information and results show the capability of neural network data fusion to improve stress measurement accuracy

    MPPT Improvement for PMSG-Based Wind Turbines Using Extended Kalman Filter and Fuzzy Control System

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    Variable speed wind turbines are commonly used as wind power generation systems because of their lower maintenance cost and flexible speed control. The optimum output power for a wind turbine can be extracted using maximum power point tracking (MPPT) strategies. However, unpredictable parameters, such as wind speed and air density could affect the accuracy of the MPPT methods, especially during the wind speed small oscillations. In this paper, in a permanent magnet synchronous generator (PMSG), the MPPT is implemented by determining the uncertainty of the unpredictable parameters using the extended Kalman filter (EKF). Also, the generator speed is controlled by employing a fuzzy logic control (FLC) system. This study aims at minimizing the effects of unpredictable parameters on the MPPT of the PMSG system. The simulation results represent an improvement in MPPT accuracy and output power efficiency
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