Signals Pub Date : 2023-09-26 DOI: 10.3390/signals4040037

Ryo Matsuoka, Masahiro Okuda

{"title":"Beyond Staircasing Effect: Robust Image Smoothing via ℓ0 Gradient Minimization and Novel Gradient Constraints","authors":"Ryo Matsuoka, Masahiro Okuda","doi":"10.3390/signals4040037","DOIUrl":"https://doi.org/10.3390/signals4040037","url":null,"abstract":"In this paper, we propose robust image-smoothing methods based on ℓ0 gradient minimization with novel gradient constraints to effectively suppress pseudo-edges. Simultaneously minimizing the ℓ0 gradient, i.e., the number of nonzero gradients in an image, and the ℓ2 data fidelity results in a smooth image. However, this optimization often leads to undesirable artifacts, such as pseudo-edges, known as the “staircasing effect”, and halos, which become more visible in image enhancement tasks, like detail enhancement and tone mapping. To address these issues, we introduce two types of gradient constraints: box and ball. These constraints are applied using a reference image (e.g., the input image is used as a reference for image smoothing) to suppress pseudo-edges in homogeneous regions and the blurring effect around strong edges. We also present an ℓ0 gradient minimization problem based on the box-/ball-type gradient constraints using an alternating direction method of multipliers (ADMM). Experimental results on important applications of ℓ0 gradient minimization demonstrate the advantages of our proposed methods compared to existing ℓ0 gradient-based approaches.","PeriodicalId":93815,"journal":{"name":"Signals","volume":"2012 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134887083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Localizing the First Interstellar Meteor with Seismometer Data 用地震仪数据定位第一颗星际流星

Signals Pub Date : 2023-09-25 DOI: 10.3390/signals4040035

Amir Siraj, Abraham Loeb

引用次数: 1

Improved RSSI Indoor Localization in IoT Systems with Machine Learning Algorithms 利用机器学习算法改进物联网系统中的RSSI室内定位

Signals Pub Date : 2023-09-25 DOI: 10.3390/signals4040036

Madduma Wellalage Pasan Maduranga, Valmik Tilwari, Ruvan Abeysekera

{"title":"Improved RSSI Indoor Localization in IoT Systems with Machine Learning Algorithms","authors":"Madduma Wellalage Pasan Maduranga, Valmik Tilwari, Ruvan Abeysekera","doi":"10.3390/signals4040036","DOIUrl":"https://doi.org/10.3390/signals4040036","url":null,"abstract":"Recent developments in machine learning algorithms are playing a significant role in wireless communication and Internet of Things (IoT) systems. Location-based Internet of Things services (LBIoTS) are considered one of the primary applications among those IoT applications. The key information involved in LBIoTS is finding an object’s geographical location. The Global Positioning System (GPS) technique does not perform better in indoor environments due to multipath. Numerous methods have been investigated for indoor localization scenarios. However, the precise location estimation of a moving object in such an application is challenging due to the high signal fluctuations. Therefore, this paper presents machine learning algorithms to estimate the object’s location based on the Received Signal Strength Indicator (RSSI) values collected through Bluetooth low-energy (BLE)-based nodes. In this experiment, we utilize a publicly available RSSI dataset. The RSSI data are collected from different BLE ibeacon nodes installed in a complex indoor environment with labels. Then, the RSSI data are linearized using the weighted least-squares method and filtered using moving average filters. Moreover, machine learning algorithms are used for training and testing the dataset to estimate the precise location of the objects. All the proposed algorithms were tested and evaluated under their different hyperparameters. The tested models provided approximately 85% accuracy for KNN, 84% for SVM and 76% accuracy in FFNN.","PeriodicalId":93815,"journal":{"name":"Signals","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135817832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Early Signatures of Brain Injury in the Preterm Neonatal EEG 早产儿脑电图的早期脑损伤特征

Signals Pub Date : 2023-09-06 DOI: 10.3390/signals4030034

H. Abbasi, Malcolm R. Battin, Robyn Butler, Deborah Rowe, Benjamin A. Lear, A. Gunn, L. Bennet

{"title":"Early Signatures of Brain Injury in the Preterm Neonatal EEG","authors":"H. Abbasi, Malcolm R. Battin, Robyn Butler, Deborah Rowe, Benjamin A. Lear, A. Gunn, L. Bennet","doi":"10.3390/signals4030034","DOIUrl":"https://doi.org/10.3390/signals4030034","url":null,"abstract":"Reliable prognostic biomarkers are needed to support the early diagnosis of brain injury in extremely preterm infants, and to develop effective neuroprotective protocols that are tailored to the progressing phases of injury. Experimental and clinical research shows that severity of neuronal damage is correlated with changes in the electroencephalogram (EEG) after hypoxic-ischemia (HI). We have previously reported that micro-scale sharp-wave EEG waveforms have prognostic utility within the early hours of post-HI recordings in preterm fetal sheep, before injury develops. This article aims to investigate whether these subtle EEG patterns are translational in the early hours of life in clinical recordings from extremely preterm newborns. This work evaluates the existence and morphological similarity of the sharp-waves automatically identified throughout the entire duration of EEG data from a cohort of fetal sheep 6 h after HI (n = 7, at 103 ± 1 day gestation) and in recordings commencing before 6 h of life in extremely preterm neonates (n = 7, 27 ± 2.0 weeks gestation). We report that micro-scale EEG waveforms with similar morphology and characteristics (r = 0.94) to those seen in fetal sheep after HI are also present after birth in recordings started before 6 h of life in extremely preterm neonates. This work further indicates that the post-HI sharp-waves show rapid morphological evolution, influenced by age and/or severity of neuronal loss, and thus that automated algorithms should be validated against such signal variations. Finally, this article discusses the need for more focused research on the early assessment of EEG changes in preterm infants to help determine the timing of brain injury to identify biomarkers that could assist in targeting novel therapies for particular phases of injury.","PeriodicalId":93815,"journal":{"name":"Signals","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41839697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Design of Adaptive Kalman Consensus Filters (a-KCF) 自适应卡尔曼一致滤波器(a-KCF)设计

Signals Pub Date : 2023-08-31 DOI: 10.3390/signals4030033

Shalin Ye, Shufan Wu

引用次数: 0

Auditing Accessibility of Pavements and Points of Interest in Urban Areas: The ‘Seek & Go’ Tool 审计城市地区人行道和兴趣点的可达性:“寻找和走”工具

Signals Pub Date : 2023-08-23 DOI: 10.3390/signals4030032

C. Achillas, D. Aidonis, N. Tsolakis, Ioannis Tsampoulatidis, A. Mourouzis, Christos Bialas, Kyriakos Koritsoglou

{"title":"Auditing Accessibility of Pavements and Points of Interest in Urban Areas: The ‘Seek & Go’ Tool","authors":"C. Achillas, D. Aidonis, N. Tsolakis, Ioannis Tsampoulatidis, A. Mourouzis, Christos Bialas, Kyriakos Koritsoglou","doi":"10.3390/signals4030032","DOIUrl":"https://doi.org/10.3390/signals4030032","url":null,"abstract":"In recent years, accessibility has become a topic of great interest on a global scale across the scientific, business, and policy sectors. There are two primary reasons for this growing trend. Firstly, accessibility serves as a vital indicator reflecting the social performance of communities, and the public is increasingly aware of critical social issues such as accessibility. Secondly, accessibility is essential for the sustainable development of regions and civil settings, facilitating inclusion and business growth. In this regard, information and communications technologies can play a crucial role in facilitating the accessibility of spaces by disabled people. Numerous digital tools and smart applications are already available to serve this purpose. This study presents a novel digital tool called ‘Seek & Go’, a comprehensive aid application designed specifically for disabled individuals. The app features a GPS navigation system that caters to pedestrians with disabilities and unique accessibility requirements. The present study documents the models underlying the development of ‘Seek & Go’, discusses technical aspects of the application, and presents user experience insights.","PeriodicalId":93815,"journal":{"name":"Signals","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43337388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Resource Allocation of UAV-Assisted IoT Node Secure Communication System 无人机辅助物联网节点安全通信系统的资源分配

Signals Pub Date : 2023-08-21 DOI: 10.3390/signals4030031

Biyun Ma, Diyuan Xu, Xinyu Ren, Yide Wang, Jiaojiao Liu

引用次数: 1

A Nonlinear Optimization Design Algorithm for Nearly Linear-Phase 2D IIR Digital Filters 近线性相位二维IIR数字滤波器的非线性优化设计算法

Signals Pub Date : 2023-08-02 DOI: 10.3390/signals4030030

A. Omar, D. Shpak, P. Agathoklis, B. Moa

{"title":"A Nonlinear Optimization Design Algorithm for Nearly Linear-Phase 2D IIR Digital Filters","authors":"A. Omar, D. Shpak, P. Agathoklis, B. Moa","doi":"10.3390/signals4030030","DOIUrl":"https://doi.org/10.3390/signals4030030","url":null,"abstract":"In this paper, a new optimization method for the design of nearly linear-phase two-dimensional infinite impulse (2D IIR) digital filters with a separable denominator is proposed. A design framework for 2D IIR digital filters is formulated as a nonlinear constrained optimization problem where the group delay deviation in the passband is minimized under prescribed soft magnitude constraints and hard stability requirements. To achieve this goal, sub-level sets of the group delay deviations are utilized to generate a sequence of filters, from which the one with the best performance is selected. The quality of the obtained filter is evaluated using three quality factors, namely, the passband magnitude quality factor Qh and the group delay deviation quality factor Qτ, while the third one is a new quality factor Qs that assesses the performance in the stopband relative to the minimum filter gain in the passband. The proposed framework is implemented using the interior-point (IP) method in a MATLAB environment, and the experimental results show that filters designed using the proposed method have good magnitude response and low group delay deviation. The performance of the resulting filters is compared with the results of other methods.","PeriodicalId":93815,"journal":{"name":"Signals","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44229332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Computer Vision and Image Processing in Structural Health Monitoring: Overview of Recent Applications 计算机视觉和图像处理在结构健康监测中的最新应用综述

Signals Pub Date : 2023-07-24 DOI: 10.3390/signals4030029

Claudia Ferraris, G. Amprimo, G. Pettiti

{"title":"Computer Vision and Image Processing in Structural Health Monitoring: Overview of Recent Applications","authors":"Claudia Ferraris, G. Amprimo, G. Pettiti","doi":"10.3390/signals4030029","DOIUrl":"https://doi.org/10.3390/signals4030029","url":null,"abstract":"Structural deterioration is a primary long-term concern resulting from material wear and tear, events, solicitations, and disasters that can progressively compromise the integrity of a cement-based structure until it suddenly collapses, becoming a potential and latent danger to the public. For many years, manual visual inspection has been the only viable structural health monitoring (SHM) solution. Technological advances have led to the development of sensors and devices suitable for the early detection of changes in structures and materials using automated or semi-automated approaches. Recently, solutions based on computer vision, imaging, and video signal analysis have gained momentum in SHM due to increased processing and storage performance, the ability to easily monitor inaccessible areas (e.g., through drones and robots), and recent progress in artificial intelligence fueling automated recognition and classification processes. This paper summarizes the most recent studies (2018–2022) that have proposed solutions for the SHM of infrastructures based on optical devices, computer vision, and image processing approaches. The preliminary analysis revealed an initial subdivision into two macro-categories: studies that implemented vision systems and studies that accessed image datasets. Each study was then analyzed in more detail to present a qualitative description related to the target structures, type of monitoring, instrumentation and data source, methodological approach, and main results, thus providing a more comprehensive overview of the recent applications in SHM and facilitating comparisons between the studies.","PeriodicalId":93815,"journal":{"name":"Signals","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43540168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Improving Foraminifera Classification Using Convolutional Neural Networks with Ensemble Learning 基于集成学习的卷积神经网络改进有孔虫分类

Signals Pub Date : 2023-07-17 DOI: 10.3390/signals4030028

L. Nanni, Giovanni Faldani, S. Brahnam, Riccardo Bravin, Elia Feltrin

引用次数: 0

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