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Anonymous Traffic Detection Based on Feature Engineering and Reinforcement Learning 基于特征工程和强化学习的匿名流量检测
Pub Date : 2024-04-01 DOI: 10.3390/s24072295
Dazhou Liu, Younghee Park
Anonymous networks, which aim primarily to protect user identities, have gained prominence as tools for enhancing network security and anonymity. Nonetheless, these networks have become a platform for adversarial affairs and sources of suspicious attack traffic. To defend against unpredictable adversaries on the Internet, detecting anonymous network traffic has emerged as a necessity. Many supervised approaches to identify anonymous traffic have harnessed machine learning strategies. However, many require access to engineered datasets and complex architectures to extract the desired information. Due to the resistance of anonymous network traffic to traffic analysis and the scarcity of publicly available datasets, those approaches may need to improve their training efficiency and achieve a higher performance when it comes to anonymous traffic detection. This study utilizes feature engineering techniques to extract pattern information and rank the feature importance of the static traces of anonymous traffic. To leverage these pattern attributes effectively, we developed a reinforcement learning framework that encompasses four key components: states, actions, rewards, and state transitions. A lightweight system is devised to classify anonymous and non-anonymous network traffic. Subsequently, two fine-tuned thresholds are proposed to substitute the traditional labels in a binary classification system. The system will identify anonymous network traffic without reliance on labeled data. The experimental results underscore that the system can identify anonymous traffic with an accuracy rate exceeding 80% (when based on pattern information).
匿名网络的主要目的是保护用户身份,作为加强网络安全和匿名性的工具,匿名网络的地位日益突出。然而,这些网络已成为敌对事务的平台和可疑攻击流量的来源。为了抵御互联网上不可预测的对手,检测匿名网络流量已成为一种必要。许多识别匿名流量的监督方法都采用了机器学习策略。然而,许多方法需要访问工程数据集和复杂的架构才能提取所需的信息。由于匿名网络流量对流量分析的阻力以及公开可用数据集的稀缺性,这些方法可能需要提高训练效率,并在匿名流量检测方面实现更高的性能。本研究利用特征工程技术提取匿名流量静态痕迹的模式信息,并对其特征重要性进行排序。为了有效利用这些模式属性,我们开发了一个强化学习框架,其中包括四个关键部分:状态、行动、奖励和状态转换。我们设计了一个轻量级系统来对匿名和非匿名网络流量进行分类。随后,提出了两个微调阈值来替代二元分类系统中的传统标签。该系统无需依赖标签数据就能识别匿名网络流量。实验结果表明,该系统识别匿名流量的准确率超过 80%(基于模式信息)。
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引用次数: 0
Incremental Clustering for Predictive Maintenance in Cryogenics for Radio Astronomy 用于射电天文学低温设备预测性维护的增量聚类技术
Pub Date : 2024-04-01 DOI: 10.3390/s24072278
Alessandro Cabras, P. Ortu, T. Pisanu, Paolo Maxia, Roberto Caocci
In a cooling system for radio astronomy receivers, maintaining cold heads and compressors is essential for consistent performance. This project focuses on monitoring the power currents of the cold head’s motor to address potential mechanical deterioration, which could jeopardize the overall functionality of the system. Using Hall effect sensors, a microcontroller-based electronic board, and artificial intelligence, the system detects and predicts anomalies. The model operates using an unsupervised approach based on incremental clustering. Since potential fault scenarios can be multiple and often challenging to simulate or identify during training, the system is initially trained using known operational categories. Over time, the system adapts and evolves by incorporating new data, which can be assigned to existing categories or, in the case of new anomalies, form new categories. This incremental approach enables the system to enhance its performance over the years, adapting to new anomaly scenarios and ensuring precise and reliable monitoring of the cold head’s health.
在射电天文接收机的冷却系统中,冷头和压缩机的维护对于保持性能稳定至关重要。本项目的重点是监测冷头电机的功率电流,以解决可能危及系统整体功能的潜在机械老化问题。该系统利用霍尔效应传感器、基于微控制器的电子板和人工智能来检测和预测异常情况。该模型采用基于增量聚类的无监督方法运行。由于潜在的故障情况可能是多种多样的,而且在训练过程中往往难以模拟或识别,因此系统最初使用已知的操作类别进行训练。随着时间的推移,系统会通过纳入新数据进行调整和演化,这些数据可以分配到现有类别中,或者在出现新的异常情况时,形成新的类别。这种循序渐进的方法使系统能够随着时间的推移不断提高性能,适应新的异常情况,确保对冷头健康状况进行精确可靠的监控。
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引用次数: 0
Accurate Nonstandard Path Integral Models for Arbitrary Dielectric Boundaries in 2-D NS-FDTD Domains 二维 NS-FDTD 域中任意介质边界的精确非标准路径积分模型
Pub Date : 2024-04-01 DOI: 10.3390/s24072373
T. Ohtani, Y. Kanai, N. Kantartzis
An efficient path integral (PI) model for the accurate analysis of curved dielectric structures on coarse grids via the two-dimensional nonstandard finite-difference time-domain (NS-FDTD) technique is introduced in this paper. In contrast to previous PI implementations of the perfectly electric conductor case, which accommodates orthogonal cells in the vicinity of curved surfaces, the novel PI model employs the occupation ratio of dielectrics in the necessary cells, providing thus a straightforward and instructive means to treat an assortment of practical applications. For its verification, the reflection from a flat plate and the scattering from a cylinder using the PI model are investigated. Results indicate that the featured methodology can enable the reliable and precise modeling of arbitrarily shaped dielectrics in the NS-FDTD algorithm on coarse grids.
本文介绍了一种高效的路径积分(PI)模型,用于通过二维非标准有限差分时域(NS-FDTD)技术精确分析粗网格上的弯曲介电结构。与以往完全电导体情况下的 PI 实现(在弯曲表面附近采用正交单元)不同,新的 PI 模型采用了必要单元中介质的占位比,从而为处理各种实际应用提供了直接而有指导意义的方法。为了验证该模型,我们使用 PI 模型研究了平板的反射和圆柱体的散射。结果表明,在粗网格上的 NS-FDTD 算法中,该特色方法可以对任意形状的电介质进行可靠而精确的建模。
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引用次数: 0
Industrial Fault Detection Employing Meta Ensemble Model Based on Contact Sensor Ultrasonic Signal 基于接触传感器超声波信号的元集合模型的工业故障检测
Pub Date : 2024-04-01 DOI: 10.3390/s24072297
Amirhossein Moshrefi, H. H. Tawfik, M. Elsayed, F. Nabki
Ultrasonic diagnostics is the earliest way to predict industrial faults. Usually, a contact microphone is employed for detection, but the recording will be contaminated with noise. In this paper, a dataset that contains 10 main faults of pipelines and motors is analyzed from which 30 different features in the time and frequency domains are extracted. Afterward, for dimensionality reduction, principal component analysis (PCA), linear discriminant analysis (LDA), and t-distributed stochastic neighbor embedding (t-SNE) are performed. In the subsequent phase, recursive feature elimination (RFE) is employed as a strategic method to analyze and select the most relevant features for the classifiers. Next, predictive models consisting of k-Nearest Neighbor (KNN), Logistic Regression (LR), Decision Tree (DT), Gaussian Naive Bayes (GNB), and Support Vector Machine (SVM) are employed. Then, in order to solve the classification problem, a stacking classifier based on a meta-classifier which combines multiple classification models is introduced. Furthermore, the k-fold cross-validation technique is employed to assess the effectiveness of the model in handling new data for the evaluation of experimental results in ultrasonic fault detection. With the proposed method, the accuracy is around 5% higher over five cross folds with the least amount of variation. The timing evaluation of the meta model on the 64 MHz Cortex M4 microcontroller unit (MCU) revealed an execution time of 11 ms, indicating it could be a promising solution for real-time monitoring.
超声波诊断是预测工业故障的最早方法。通常使用接触式麦克风进行检测,但记录会受到噪声的污染。本文分析了包含管道和电机 10 种主要故障的数据集,从中提取了 30 种不同的时域和频域特征。之后,为了降低维度,进行了主成分分析(PCA)、线性判别分析(LDA)和 t 分布随机邻域嵌入(t-SNE)。在随后的阶段,采用递归特征消除法(RFE)作为一种策略方法,为分类器分析和选择最相关的特征。接下来,预测模型包括 k-Nearest Neighbor (KNN)、Logistic Regression (LR)、Decision Tree (DT)、Gaussian Naive Bayes (GNB) 和 Support Vector Machine (SVM)。然后,为了解决分类问题,引入了基于元分类器的堆叠分类器,该分类器结合了多个分类模型。此外,在超声波故障检测的实验结果评估中,采用了 k 折交叉验证技术来评估模型处理新数据的有效性。采用所提出的方法,在五次交叉验证中,准确率提高了约 5%,且变化量最小。在 64 MHz Cortex M4 微控制器单元(MCU)上对元模型进行的时序评估显示,执行时间为 11 毫秒,这表明它是一种很有前途的实时监测解决方案。
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引用次数: 0
Biomechanical Assessment Methods Used in Chronic Stroke: A Scoping Review of Non-Linear Approaches 用于慢性中风的生物力学评估方法:非线性方法范围综述
Pub Date : 2024-04-01 DOI: 10.3390/s24072338
Marta Freitas, Francisco Pinho, Liliana Pinho, Sandra Silva, Vânia Figueira, J. Vilas-Boas, Augusta Silva
Non-linear and dynamic systems analysis of human movement has recently become increasingly widespread with the intention of better reflecting how complexity affects the adaptability of motor systems, especially after a stroke. The main objective of this scoping review was to summarize the non-linear measures used in the analysis of kinetic, kinematic, and EMG data of human movement after stroke. PRISMA-ScR guidelines were followed, establishing the eligibility criteria, the population, the concept, and the contextual framework. The examined studies were published between 1 January 2013 and 12 April 2023, in English or Portuguese, and were indexed in the databases selected for this research: PubMed®, Web of Science®, Institute of Electrical and Electronics Engineers®, Science Direct® and Google Scholar®. In total, 14 of the 763 articles met the inclusion criteria. The non-linear measures identified included entropy (n = 11), fractal analysis (n = 1), the short-term local divergence exponent (n = 1), the maximum Floquet multiplier (n = 1), and the Lyapunov exponent (n = 1). These studies focused on different motor tasks: reaching to grasp (n = 2), reaching to point (n = 1), arm tracking (n = 2), elbow flexion (n = 5), elbow extension (n = 1), wrist and finger extension upward (lifting) (n = 1), knee extension (n = 1), and walking (n = 4). When studying the complexity of human movement in chronic post-stroke adults, entropy measures, particularly sample entropy, were preferred. Kinematic assessment was mainly performed using motion capture systems, with a focus on joint angles of the upper limbs.
人类运动的非线性和动态系统分析近来越来越广泛,目的是更好地反映复杂性如何影响运动系统的适应性,尤其是中风后。本范围综述的主要目的是总结用于分析中风后人体运动的动力学、运动学和肌电图数据的非线性测量方法。研究遵循 PRISMA-ScR 指南,确定了资格标准、研究人群、概念和背景框架。所考察的研究发表于 2013 年 1 月 1 日至 2023 年 4 月 12 日之间,语言为英语或葡萄牙语,并被本研究选定的数据库收录:PubMed®、Web of Science®、Institute of Electrical and Electronics Engineers®、Science Direct® 和 Google Scholar®。在 763 篇文章中,共有 14 篇符合纳入标准。确定的非线性测量包括熵(n = 11)、分形分析(n = 1)、短期局部发散指数(n = 1)、最大 Floquet 乘数(n = 1)和 Lyapunov 指数(n = 1)。这些研究主要针对不同的运动任务:伸手抓取(n = 2)、伸手指向(n = 1)、手臂追踪(n = 2)、肘关节屈曲(n = 5)、肘关节伸展(n = 1)、手腕和手指向上伸展(抬起)(n = 1)、膝关节伸展(n = 1)和行走(n = 4)。在研究慢性中风后成年人的人体运动复杂性时,首选熵测量法,尤其是样本熵。运动学评估主要通过运动捕捉系统进行,重点是上肢的关节角度。
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引用次数: 0
Near-InfraRed Spectroscopy Provides a Reproducible Estimate of Muscle Aerobic Capacity, but Not Whole-Body Aerobic Power 近红外光谱可提供肌肉有氧能力的可重复估算值,但不能提供全身有氧功率的估算值
Pub Date : 2024-04-01 DOI: 10.3390/s24072277
T. Venckunas, Andrius Satas, M. Brazaitis, N. Eimantas, S. Sipaviciene, S. Kamandulis
Near-infrared spectroscopy (NIRS) during repeated limb occlusions is a noninvasive tool for assessing muscle oxidative capacity. However, the method’s reliability and validity remain under investigation. This study aimed to determine the reliability of the NIRS-derived mitochondrial power of the musculus vastus lateralis and its correlation with whole-body (cycling) aerobic power (V˙O2 peak). Eleven healthy active men (28 ± 10 y) twice (2 days apart) underwent repeated arterial occlusions to induce changes in muscle oxygen delivery after 15 s of electrical muscle stimulation. The muscle oxygen consumption (mV˙O2) recovery time and rate (k) constants were calculated from the NIRS O2Hb signal. We assessed the reliability (coefficient of variation and intraclass coefficient of correlation [ICC]) and equivalency (t-test) between visits. The results showed high reproducibility for the mV˙O2 recovery time constant (ICC = 0.859) and moderate reproducibility for the k value (ICC = 0.674), with no significant differences between visits (p > 0.05). NIRS-derived k did not correlate with the V˙O2 peak relative to body mass (r = 0.441, p = 0.17) or the absolute V˙O2 peak (r = 0.366, p = 0.26). In conclusion, NIRS provides a reproducible estimate of muscle mitochondrial power, which, however, was not correlated with whole-body aerobic capacity in the current study, suggesting that even if somewhat overlapping, not the same set of factors underpin these distinct indices of aerobic capacity at the different (peripheral and whole-body systemic) levels.
重复肢体闭塞时的近红外光谱(NIRS)是评估肌肉氧化能力的一种无创工具。然而,该方法的可靠性和有效性仍有待研究。本研究旨在确定 NIRS 得出的外侧肌线粒体功率的可靠性及其与全身(骑自行车)有氧功率(V˙O2 峰值)的相关性。对 11 名健康的活动男子(28 ± 10 岁)进行了两次(间隔 2 天)反复动脉闭塞,以诱导肌肉电刺激 15 秒后肌肉氧输送的变化。根据近红外光谱 O2Hb 信号计算肌肉耗氧量(mV˙O2)恢复时间和速率(k)常数。我们评估了各次访问之间的可靠性(变异系数和类内相关系数 [ICC])和等效性(t 检验)。结果表明,mV˙O2 恢复时间常数(ICC = 0.859)和 k 值(ICC = 0.674)具有较高的可重复性,不同检查之间无显著差异(p > 0.05)。NIRS 导出的 k 与相对于体重的 V˙O2 峰值(r = 0.441,p = 0.17)或 V˙O2 绝对峰值(r = 0.366,p = 0.26)不相关。总之,近红外光谱可提供可重复的肌肉线粒体功率估计值,但在当前的研究中,该估计值与全身有氧能力并不相关,这表明即使有些重叠,但在不同(外周和全身系统)水平上,支撑这些不同的有氧能力指数的因素并不相同。
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引用次数: 0
ZYNQ-Based Visible Light Defogging System Design Realization 基于 ZYNQ 的可见光除雾系统设计实现
Pub Date : 2024-04-01 DOI: 10.3390/s24072276
Bohan Liu, Qihai Wei, Kun Ding
Under a foggy environment, the air contains a large number of suspended particles, which lead to the loss of image information and decline of contrast collected by the vision system. This makes subsequent processing and analysis difficult. At the same time, the current stage of the defogging system has problems such as high hardware cost and poor real-time processing. In this article, an image defogging system is designed based on the ZYNQ platform. First of all, on the basis of the traditional dark-channel defogging algorithm, an algorithm for segmenting the sky is proposed, and in this way, the image distortion caused by the sky region is avoided, and the atmospheric light value and transmittance are estimated more accurately. Then color balancing is performed after image defogging to improve the quality of the final output image. The parallel computing advantage and logic resources of the PL (Programmable Logic) part (FPGA) of ZYNQ are fully utilized through instruction constraints and logic optimization. Finally, the visible light detector is used as the input to build a real-time video processing experiment platform. The experimental results show that the system has a good defogging effect and meet the real-time requirements.
在大雾环境下,空气中含有大量悬浮颗粒,导致视觉系统采集到的图像信息丢失和对比度下降。这给后续处理和分析带来了困难。同时,现阶段的除雾系统还存在硬件成本高、实时处理能力差等问题。本文基于 ZYNQ 平台设计了一种图像除雾系统。首先,在传统暗色道除雾算法的基础上,提出了一种分割天空的算法,这样既避免了天空区域造成的图像失真,又能更准确地估计大气光值和透射率。然后在图像除雾后进行色彩平衡,以提高最终输出图像的质量。通过指令约束和逻辑优化,ZYNQ 的 PL(可编程逻辑)部分(FPGA)的并行计算优势和逻辑资源得到了充分利用。最后,以可见光探测器为输入,搭建了实时视频处理实验平台。实验结果表明,该系统具有良好的除雾效果,满足实时性要求。
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引用次数: 0
Automated Pavement Condition Index Assessment with Deep Learning and Image Analysis: An End-to-End Approach 利用深度学习和图像分析自动评估路面状况指数:端到端方法
Pub Date : 2024-04-01 DOI: 10.3390/s24072333
Eldor B. Ibragimov, Yongsoo Kim, Jung Hee Lee, Junsang Cho, Jong-Jae Lee
The degradation of road pavements due to environmental factors is a pressing issue in infrastructure maintenance, necessitating precise identification of pavement distresses. The pavement condition index (PCI) serves as a critical metric for evaluating pavement conditions, essential for effective budget allocation and performance tracking. Traditional manual PCI assessment methods are limited by labor intensity, subjectivity, and susceptibility to human error. Addressing these challenges, this paper presents a novel, end-to-end automated method for PCI calculation, integrating deep learning and image processing technologies. The first stage employs a deep learning algorithm for accurate detection of pavement cracks, followed by the application of a segmentation-based skeleton algorithm in image processing to estimate crack width precisely. This integrated approach enhances the assessment process, providing a more comprehensive evaluation of pavement integrity. The validation results demonstrate a 95% accuracy in crack detection and 90% accuracy in crack width estimation. Leveraging these results, the automated PCI rating is achieved, aligned with standards, showcasing significant improvements in the efficiency and reliability of PCI evaluations. This method offers advancements in pavement maintenance strategies and potential applications in broader road infrastructure management.
环境因素导致的路面退化是基础设施维护中的一个紧迫问题,需要对路面状况进行精确识别。路面状况指数(PCI)是评估路面状况的关键指标,对于有效的预算分配和性能跟踪至关重要。传统的人工 PCI 评估方法因劳动强度大、主观性强和容易出现人为错误而受到限制。为了应对这些挑战,本文提出了一种新颖的、端到端的 PCI 自动计算方法,集成了深度学习和图像处理技术。第一阶段采用深度学习算法精确检测路面裂缝,随后在图像处理中应用基于分割的骨架算法精确估算裂缝宽度。这种综合方法增强了评估过程,为路面完整性提供了更全面的评估。验证结果表明,裂缝检测的准确率为 95%,裂缝宽度估算的准确率为 90%。利用这些结果,实现了与标准一致的自动 PCI 评级,显著提高了 PCI 评估的效率和可靠性。这种方法为路面维护策略提供了进步,并有可能应用于更广泛的道路基础设施管理。
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引用次数: 0
Vehicle Position Detection Based on Machine Learning Algorithms in Dynamic Wireless Charging 动态无线充电中基于机器学习算法的车辆位置检测
Pub Date : 2024-04-01 DOI: 10.3390/s24072346
Milad Behnamfar, Alexander Stevenson, Mohd Tariq, Arif Sarwat
Dynamic wireless charging (DWC) has emerged as a viable approach to mitigate range anxiety by ensuring continuous and uninterrupted charging for electric vehicles in motion. DWC systems rely on the length of the transmitter, which can be categorized into long-track transmitters and segmented coil arrays. The segmented coil array, favored for its heightened efficiency and reduced electromagnetic interference, stands out as the preferred option. However, in such DWC systems, the need arises to detect the vehicle’s position, specifically to activate the transmitter coils aligned with the receiver pad and de-energize uncoupled transmitter coils. This paper introduces various machine learning algorithms for precise vehicle position determination, accommodating diverse ground clearances of electric vehicles and various speeds. Through testing eight different machine learning algorithms and comparing the results, the random forest algorithm emerged as superior, displaying the lowest error in predicting the actual position.
动态无线充电(DWC)可确保为行驶中的电动汽车提供连续不间断的充电,是缓解续航里程焦虑的一种可行方法。DWC 系统依赖于发射器的长度,可分为长轨道发射器和分段线圈阵列。分段线圈阵列因其效率高、电磁干扰少而备受青睐,是首选方案。然而,在这种 DWC 系统中,需要检测车辆的位置,特别是激活与接收器垫对齐的发射器线圈,并解除未耦合发射器线圈的供电。本文介绍了用于精确确定车辆位置的各种机器学习算法,以适应电动汽车不同的地面间隙和不同的速度。通过测试八种不同的机器学习算法并对结果进行比较,随机森林算法表现出色,在预测实际位置时误差最小。
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引用次数: 0
Multi-Task Foreground-Aware Network with Depth Completion for Enhanced RGB-D Fusion Object Detection Based on Transformer 基于变换器的多任务前景感知网络与深度补全用于增强型 RGB-D 融合对象检测
Pub Date : 2024-04-01 DOI: 10.3390/s24072374
Jiasheng Pan, Songyi Zhong, Tao Yue, Yankun Yin, Yanhao Tang
Fusing multiple sensor perceptions, specifically LiDAR and camera, is a prevalent method for target recognition in autonomous driving systems. Traditional object detection algorithms are limited by the sparse nature of LiDAR point clouds, resulting in poor fusion performance, especially for detecting small and distant targets. In this paper, a multi-task parallel neural network based on the Transformer is constructed to simultaneously perform depth completion and object detection. The loss functions are redesigned to reduce environmental noise in depth completion, and a new fusion module is designed to enhance the network’s perception of the foreground and background. The network leverages the correlation between RGB pixels for depth completion, completing the LiDAR point cloud and addressing the mismatch between sparse LiDAR features and dense pixel features. Subsequently, we extract depth map features and effectively fuse them with RGB features, fully utilizing the depth feature differences between foreground and background to enhance object detection performance, especially for challenging targets. Compared to the baseline network, improvements of 4.78%, 8.93%, and 15.54% are achieved in the difficult indicators for cars, pedestrians, and cyclists, respectively. Experimental results also demonstrate that the network achieves a speed of 38 fps, validating the efficiency and feasibility of the proposed method.
在自动驾驶系统中,融合多种传感器感知(特别是激光雷达和摄像头)是一种普遍的目标识别方法。传统的目标检测算法受限于激光雷达点云的稀疏性,导致融合性能不佳,尤其是在检测小型和远距离目标时。本文构建了一个基于变换器的多任务并行神经网络,可同时执行深度补全和目标检测。对损失函数进行了重新设计,以减少深度补全中的环境噪声,并设计了一个新的融合模块,以增强网络对前景和背景的感知。该网络利用 RGB 像素之间的相关性进行深度补全,补全激光雷达点云并解决稀疏激光雷达特征与密集像素特征之间的不匹配问题。随后,我们提取深度图特征,并将其与 RGB 特征有效融合,充分利用前景和背景之间的深度特征差异来提高物体检测性能,尤其是对于具有挑战性的目标。与基线网络相比,在汽车、行人和骑自行车者的高难度指标上分别提高了 4.78%、8.93% 和 15.54%。实验结果还表明,该网络的速度达到了 38 fps,验证了所提方法的效率和可行性。
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引用次数: 0
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Sensors (Basel, Switzerland)
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