Explore the vast range of titles available.

It is an undeniable fact that Internet of Things (IoT) technologies have become a milestone advancement in the digital healthcare domain, since the number of IoT medical devices is grown exponentially, and it is now anticipated that by 2020 there will be over 161 million of them connected worldwide. Therefore, in an era of continuous growth, IoT healthcare faces various challenges, such as the collection, the quality estimation, as well as the interpretation and the harmonization of the data that derive from the existing huge amounts of heterogeneous IoT medical devices. Even though various approaches have been developed so far for solving each one of these challenges, none of these proposes a holistic approach for successfully achieving data interoperability between high-quality data that derive from heterogeneous devices. For that reason, in this manuscript a mechanism is produced for effectively addressing the intersection of these challenges. Through this mechanism, initially, the collection of the different devices’ datasets occurs, followed by the cleaning of them. In sequel, the produced cleaning results are used in order to capture the levels of the overall data quality of each dataset, in combination with the measurements of the availability of each device that produced each dataset, and the reliability of it. Consequently, only the high-quality data is kept and translated into a common format, being able to be used for further utilization. The proposed mechanism is evaluated through a specific scenario, producing reliable results, achieving data interoperability of 100% accuracy, and data quality of more than 90% accuracy.

Sensor-based Human Activity Recognition (HAR) is crucial in ubiquitous computing, analyzing behaviors through multi-dimensional observations. Despite research progress, HAR confronts challenges, particularly in data distribution assumptions. Most studies assume uniform data distributions across datasets, contrasting with the varied nature of practical sensor data in human activities. Addressing data heterogeneity issues can improve performance, reduce computational costs, and aid in developing personalized, adaptive models with fewer annotated data. This review investigates how machine learning addresses data heterogeneity in HAR by categorizing data heterogeneity types, applying corresponding suitable machine learning methods, summarizing available datasets, and discussing future challenges.

According to the World Health Organization (WHO), pneumonia kills about 2 million children under the age of 5 every year. Traditional machine learning methods can be used to diagnose chest X-rays of pneumonia in children, but there is a privacy and security issue in centralizing the data for training. Federated learning prevents data privacy leakage by sharing only the model and not the data, and it has a wide range of application in the medical field. We use federated learning method for classification, which effectively protects data security. And for the data heterogeneity phenomenon existing in the actual scenario, which will seriously affect the classification effect, we propose a method based on two-end control variables. Specifically, based on the classical federated learning FedAvg algorithm, we modify the loss function on the client side by adding a regular term or a penalty term, and add momentum after the average aggregation on the server side. The federated learning approach prevents the data privacy leakage problem compared to the traditional machine learning approach. In order to solve the problem of low classification accuracy due to data heterogeneity, our proposed method based on two-end control variables achieves an average improvement of 2% and an accuracy of 98% on average, and 99% individually, compared to the previous federated learning algorithms and the latest diffusion model-based method. The classification results and methodology of this study can be utilized by clinicians worldwide to improve the overall detection of pediatric pneumonia.

The growing need for data privacy and security in machine learning has led to exploring novel approaches like federated learning (FL) that allow collaborative training on distributed datasets, offering a decentralized alternative to traditional data collection methods. A prime benefit of FL is its emphasis on privacy, enabling data to stay on local devices by moving models instead of data. Despite its pioneering nature, FL faces issues such as diversity in data types, model complexity, privacy concerns, and the need for efficient resource distribution. This paper illustrates an empirical analysis of these challenges within specially designed scenarios, each aimed at studying a specific problem. In particular, differently from existing literature, we isolate the issues that can arise in an FL framework to observe their nature without the interference of external factors.

Machine Learning (ML) and Deep Learning (DL) are derivatives of Artificial Intelligence (AI) that have already demonstrated their effectiveness in a variety of domains, including healthcare, where they are now routinely integrated into patients’ daily activities. On the other hand, data heterogeneity has long been a key obstacle in AI, ML and DL. Here, Multimodal Machine Learning (Multimodal ML) has emerged as a method that enables the training of complex ML and DL models that use heterogeneous data in their learning process. In addition, Multimodal ML enables the integration of multiple models in the search for a single, comprehensive solution to a complex problem. In this review, the technical aspects of Multimodal ML are discussed, including a definition of the technology and its technical underpinnings, especially data fusion. It also outlines the differences between this technology and others, such as Ensemble Learning, as well as the various workflows that can be followed in Multimodal ML. In addition, this article examines in depth the use of Multimodal ML in the detection and prediction of Cardiovascular Diseases, highlighting the results obtained so far and the possible starting points for improving its use in the aforementioned field. Finally, a number of the most common problems hindering the development of this technology and potential solutions that could be pursued in future studies are outlined.

The aim of heterogeneous federated learning (HFL) is to address the issues of data heterogeneity, computational resource disparity, and model generalizability and security in federated learning (FL). To facilitate the collaborative training of data and enhance the predictive performance of models, a heterogeneous federated learning algorithm based on contribution-weighted aggregation (HFedCWA) is proposed in this paper. First, weights are assigned on the basis of the distribution differences and quantities of heterogeneous device data, and a contribution-based weighted aggregation method is introduced to dynamically adjust weights and balance data heterogeneity. Second, personalized strategies based on regularization are formulated for heterogeneous devices with different weights, enabling each device to participate in the overall task in an optimal manner. Differential privacy methods are concurrently utilized in FL training to further enhance the security of the system. Finally, experiments are conducted under various data heterogeneity scenarios using the MNIST and CIFAR10 datasets, and the results demonstrate that the HFedCWA can effectively improve the model’s generalizability ability and adaptability to heterogeneous data, thereby enhancing the overall efficiency and performance of the HFL system.

Federated learning provides an effective solution to the data privacy issue in distributed machine learning. However, distributed federated learning systems are inherently susceptible to data poisoning attacks and data heterogeneity. Under conditions of high data heterogeneity, the gradient conflict problem in federated learning becomes more pronounced, making traditional defense mechanisms against poisoning attacks less adaptable between scenarios with and without attacks. To address this challenge, we design a two-stage federated learning framework for defending against poisoning attacks—FedCVG. During implementation, FedCVG first removes malicious clients using a reputation-based clustering method, and then optimizes communication overhead through a virtual aggregation mechanism. Extensive experimental results show that, compared to other baseline methods, FedCVG improves average accuracy by 4.2% and reduces communication overhead by approximately 50% while defending against poisoning attacks.

Federated Learning, an approach to collaborative modeling, enables the training of a unified global model across multiple clients in a decentralized manner. However, the considerable impact of local data heterogeneity on algorithm performance has attracted significant attention. In this study, we introduce a novel Federated Learning algorithm called Federated Joint Server-Client Momentum (FedJSCM) to address data heterogeneity in real-world Federated Learning applications. FedJSCM efficiently utilizes global gradient information from previous communications and adjusts client gradient descent and server model fusion by transmitting gradient momentum information. This corrective mechanism effectively mitigates biases and improves the stability of Stochastic Gradient Descent (SGD). We offer theoretical analysis to highlight the advantages of FedJSCM and conduct extensive empirical studies, showcasing its superior performance across various tasks and its robustness in the face of varying degrees of data heterogeneity. Empirical studies demonstrate that FedJSCM outperforms existing algorithms, with a 1–3% accuracy increase.

To address the model training bottleneck caused by the coupling of data silos and heterogeneity in intelligent fault diagnosis, this study proposes a Federated Supervised Contrastive Learning (FSCL) framework. Traditional methods face dual challenges: on one hand, the scarcity of fault samples in industrial scenarios and the privacy barriers to cross-institutional data sharing result in insufficient data for individual entities; on the other hand, the data heterogeneity caused by differences in equipment operating conditions significantly diminishes the model aggregation effectiveness in federated learning. To tackle these issues, FSCL integrates the federated learning paradigm with a supervised contrastive mechanism: firstly, it overcomes the limitations of data silos through distributed collaborative training, enabling multiple participants to jointly develop diagnostic models without disclosing raw data; secondly, to address the feature space mismatch induced by heterogeneous data, a hybrid contrastive loss function is designed, which constrains the similarity between local models and the global model through supervised loss, thereby enhancing the feature representation capability of the global model. Experiments on two gearbox datasets demonstrate that the FSCL framework effectively resolves the issues of data insufficiency and heterogeneity, providing a novel approach for intelligent maintenance of industrial equipment that optimizes both data efficiency and privacy protection.

Heterogeneous federated learning (HtFL) has gained significant attention due to its ability to accommodate diverse models and data from distributed combat units. The prototype-based HtFL methods were proposed to reduce the high communication cost of transmitting model parameters. These methods allow for the sharing of only class representatives between heterogeneous clients while maintaining privacy. However, existing prototype learning approaches fail to take the data distribution of clients into consideration, which results in suboptimal global prototype learning and insufficient client model personalization capabilities. To address these issues, we propose a fair trainable prototype federated learning (FedFTP) algorithm, which employs a fair sampling training prototype (FSTP) mechanism and a hyperbolic space constraints (HSC) mechanism to enhance the fairness and effectiveness of prototype learning on the server in heterogeneous environments. Furthermore, a local prototype stable update (LPSU) mechanism is proposed as a means of maintaining personalization while promoting global consistency, based on contrastive learning. Comprehensive experimental results demonstrate that FedFTP achieves state-of-the-art performance in HtFL scenarios.