在这项工作中,我们提出了一个框架,用于部署的无人驾驶汽车(UAV)的便携式接入点(PAP),以服务于一组接地节点(GNS)。除PAP和GNS外,该系统还由安装在人造结构上的一组智能反射表面(IRS)组成,以增加每焦耳的能源消耗的钻头数量,这些能量消耗被测量为全球能源效率(GEE)。 PAP的GEE轨迹是通过考虑UAV推进能量消耗和PAP电池的PEUKERT效应来设计的,PAP电池代表了精确的电池放电曲线作为无人机功耗概况的非线性功能。 GEE轨迹设计问题分为两个阶段:在第一个阶段,使用多层圆形填料方法找到了PAP的路径和可行位置,并使用替代方案计算所需的IRS相移值优化方法考虑了IRS元素的幅度和相位响应之间的相互依赖性;在第二阶段,使用新型的多轨迹设计算法计算PAP飞行速度和用户调度。数值评估表明:忽略Peukert效应高估了PAP的可用飞行时间;一定的阈值后,增加电池尺寸会减少PAP的可用飞行时间;与其他基线场景相比,IRS模块的存在改善了系统的GEE。与使用顺序凸编程和Dinkelbach算法的组合开发的单圈轨迹相比,多圈轨迹可节省更多的能量。
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在这项工作中,我们研究了一个无人驾驶系统(UAS)的可靠性和投资成本之间的权衡,该系统由一组携带无线电节点的无人机(UAVS)组成,称为Portable Access Points(PAPS)),部署以服务一组地面节点(GNS)。使用所提出的算法,给定的地理区域等效地表示为一组圆形区域,其中每个圆表示PAP的覆盖区域。然后,通过将其建模为连续的时间出生死亡马尔可夫决策过程(MDP),可以在分析上得出UAS的稳态可用性。数值评估表明,可以通过考虑GN的交通需求和分配来降低保证给定稳态可用性的投资成本。
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在这项工作中,我们优化了基于无人机(UAV)的便携式接入点(PAP)的3D轨迹,该轨迹为一组接地节点(GNS)提供无线服务。此外,根据Peukert效果,我们考虑无人机电池的实用非线性电池放电。因此,我们以一种新颖的方式提出问题,代表了基于公平的能源效率度量的最大化,并被称为公平能源效率(费用)。费用指标定义了一个系统,该系统对每用户服务的公平性和PAP的能源效率都非常重要。该法式问题采用非凸面问题的形式,并具有不可扣除的约束。为了获得解决方案,我们将问题表示为具有连续状态和动作空间的马尔可夫决策过程(MDP)。考虑到解决方案空间的复杂性,我们使用双胞胎延迟的深层确定性政策梯度(TD3)参与者 - 批判性深入强化学习(DRL)框架来学习最大化系统费用的政策。我们进行两种类型的RL培训来展示我们方法的有效性:第一种(离线)方法在整个训练阶段保持GN的位置相同;第二种方法将学习的政策概括为GN的任何安排,通过更改GN的位置,每次培训情节后。数值评估表明,忽视Peukert效应高估了PAP的播放时间,可以通过最佳选择PAP的飞行速度来解决。此外,用户公平,能源效率,因此可以通过有效地将PAP移动到GN上方,从而提高系统的费用价值。因此,我们注意到郊区,城市和茂密的城市环境的基线情景高达88.31%,272.34%和318.13%。
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Three main points: 1. Data Science (DS) will be increasingly important to heliophysics; 2. Methods of heliophysics science discovery will continually evolve, requiring the use of learning technologies [e.g., machine learning (ML)] that are applied rigorously and that are capable of supporting discovery; and 3. To grow with the pace of data, technology, and workforce changes, heliophysics requires a new approach to the representation of knowledge.
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Image classification with small datasets has been an active research area in the recent past. However, as research in this scope is still in its infancy, two key ingredients are missing for ensuring reliable and truthful progress: a systematic and extensive overview of the state of the art, and a common benchmark to allow for objective comparisons between published methods. This article addresses both issues. First, we systematically organize and connect past studies to consolidate a community that is currently fragmented and scattered. Second, we propose a common benchmark that allows for an objective comparison of approaches. It consists of five datasets spanning various domains (e.g., natural images, medical imagery, satellite data) and data types (RGB, grayscale, multispectral). We use this benchmark to re-evaluate the standard cross-entropy baseline and ten existing methods published between 2017 and 2021 at renowned venues. Surprisingly, we find that thorough hyper-parameter tuning on held-out validation data results in a highly competitive baseline and highlights a stunted growth of performance over the years. Indeed, only a single specialized method dating back to 2019 clearly wins our benchmark and outperforms the baseline classifier.
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Dataset scaling, also known as normalization, is an essential preprocessing step in a machine learning pipeline. It is aimed at adjusting attributes scales in a way that they all vary within the same range. This transformation is known to improve the performance of classification models, but there are several scaling techniques to choose from, and this choice is not generally done carefully. In this paper, we execute a broad experiment comparing the impact of 5 scaling techniques on the performances of 20 classification algorithms among monolithic and ensemble models, applying them to 82 publicly available datasets with varying imbalance ratios. Results show that the choice of scaling technique matters for classification performance, and the performance difference between the best and the worst scaling technique is relevant and statistically significant in most cases. They also indicate that choosing an inadequate technique can be more detrimental to classification performance than not scaling the data at all. We also show how the performance variation of an ensemble model, considering different scaling techniques, tends to be dictated by that of its base model. Finally, we discuss the relationship between a model's sensitivity to the choice of scaling technique and its performance and provide insights into its applicability on different model deployment scenarios. Full results and source code for the experiments in this paper are available in a GitHub repository.\footnote{https://github.com/amorimlb/scaling\_matters}
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The devastation caused by the coronavirus pandemic makes it imperative to design automated techniques for a fast and accurate detection. We propose a novel non-invasive tool, using deep learning and imaging, for delineating COVID-19 infection in lungs. The Ensembling Attention-based Multi-scaled Convolution network (EAMC), employing Leave-One-Patient-Out (LOPO) training, exhibits high sensitivity and precision in outlining infected regions along with assessment of severity. The Attention module combines contextual with local information, at multiple scales, for accurate segmentation. Ensemble learning integrates heterogeneity of decision through different base classifiers. The superiority of EAMC, even with severe class imbalance, is established through comparison with existing state-of-the-art learning models over four publicly-available COVID-19 datasets. The results are suggestive of the relevance of deep learning in providing assistive intelligence to medical practitioners, when they are overburdened with patients as in pandemics. Its clinical significance lies in its unprecedented scope in providing low-cost decision-making for patients lacking specialized healthcare at remote locations.
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Objective: Imbalances of the electrolyte concentration levels in the body can lead to catastrophic consequences, but accurate and accessible measurements could improve patient outcomes. While blood tests provide accurate measurements, they are invasive and the laboratory analysis can be slow or inaccessible. In contrast, an electrocardiogram (ECG) is a widely adopted tool which is quick and simple to acquire. However, the problem of estimating continuous electrolyte concentrations directly from ECGs is not well-studied. We therefore investigate if regression methods can be used for accurate ECG-based prediction of electrolyte concentrations. Methods: We explore the use of deep neural networks (DNNs) for this task. We analyze the regression performance across four electrolytes, utilizing a novel dataset containing over 290000 ECGs. For improved understanding, we also study the full spectrum from continuous predictions to binary classification of extreme concentration levels. To enhance clinical usefulness, we finally extend to a probabilistic regression approach and evaluate different uncertainty estimates. Results: We find that the performance varies significantly between different electrolytes, which is clinically justified in the interplay of electrolytes and their manifestation in the ECG. We also compare the regression accuracy with that of traditional machine learning models, demonstrating superior performance of DNNs. Conclusion: Discretization can lead to good classification performance, but does not help solve the original problem of predicting continuous concentration levels. While probabilistic regression demonstrates potential practical usefulness, the uncertainty estimates are not particularly well-calibrated. Significance: Our study is a first step towards accurate and reliable ECG-based prediction of electrolyte concentration levels.
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Candidate axiom scoring is the task of assessing the acceptability of a candidate axiom against the evidence provided by known facts or data. The ability to score candidate axioms reliably is required for automated schema or ontology induction, but it can also be valuable for ontology and/or knowledge graph validation. Accurate axiom scoring heuristics are often computationally expensive, which is an issue if you wish to use them in iterative search techniques like level-wise generate-and-test or evolutionary algorithms, which require scoring a large number of candidate axioms. We address the problem of developing a predictive model as a substitute for reasoning that predicts the possibility score of candidate class axioms and is quick enough to be employed in such situations. We use a semantic similarity measure taken from an ontology's subsumption structure for this purpose. We show that the approach provided in this work can accurately learn the possibility scores of candidate OWL class axioms and that it can do so for a variety of OWL class axioms.
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The rapid growth of machine translation (MT) systems has necessitated comprehensive studies to meta-evaluate evaluation metrics being used, which enables a better selection of metrics that best reflect MT quality. Unfortunately, most of the research focuses on high-resource languages, mainly English, the observations for which may not always apply to other languages. Indian languages, having over a billion speakers, are linguistically different from English, and to date, there has not been a systematic study of evaluating MT systems from English into Indian languages. In this paper, we fill this gap by creating an MQM dataset consisting of 7000 fine-grained annotations, spanning 5 Indian languages and 7 MT systems, and use it to establish correlations between annotator scores and scores obtained using existing automatic metrics. Our results show that pre-trained metrics, such as COMET, have the highest correlations with annotator scores. Additionally, we find that the metrics do not adequately capture fluency-based errors in Indian languages, and there is a need to develop metrics focused on Indian languages. We hope that our dataset and analysis will help promote further research in this area.
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