Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Major Depressive Disorder (MDD) or depression is among the most prevalent psychiatric disorders, affecting more than 300 million people worldwide. Early detection is critical for rapid intervention, which can potentially reduce the escalation of the disorder. Objective: This study used data from social media networks to explore various methods of early detection of MDDs based on analysis with artificial intelligence. Methods: Our best performing method is based on a dual approach that uses a machine learning model to detect depressed subjects and another model to identify non-depressed individuals. Results: The results of a thorough evaluation of the method following a time-aware approach that rewards early detections demonstrate that the dual model can improve current state-of-the-art detection models by more than 10%. Conclusions: Given the results, we consider that this work can help in the development of new solutions to deal with the early detection of depression on social networks.

With the rise in smart devices, the Internet of Things (IoT) has been established as one of the preferred emerging platforms to fulfil their need for simple interconnections. The use of specific protocols such as constrained application protocol (CoAP) has demonstrated improvements in the performance of the networks. However, power-, bandwidth-, and memory-constrained sensing devices constitute a weakness in the security of the system. One way to mitigate these security problems is through anomaly-based intrusion detection systems, which aim to estimate the behaviour of the systems based on their “normal” nature. Thus, to develop anomaly-based intrusion detection systems, it is necessary to have a suitable dataset that allows for their analysis. Due to the lack of a public dataset in the CoAP-IoT environment, this work aims to present a complete and labelled CoAP-IoT anomaly detection dataset (CIDAD) based on real-world traffic, with a sufficient trace size and diverse anomalous scenarios. The modelled data were implemented in a virtual sensor environment, including three types of anomalies in the CoAP data. The validation of the dataset was carried out using five shallow machine learning techniques: logistic regression, naive Bayes, random forest, AdaBoost, and support vector machine. Detailed analyses of the dataset, data conditioning, feature engineering, and hyperparameter tuning are presented. The evaluation metrics used in the performance comparison are accuracy, precision, recall, F1 score, and kappa score. The system achieved 99.9% accuracy for decision tree models. Random forest established itself as the best model, obtaining a 99.9% precision and F1 score, 100% recall, and a Cohen’s kappa statistic of 0.99.

With advancements in engineering and science, the application of smart systems is increasing, generating a faster growth of the IoT network traffic. The limitations due to IoT restricted power and computing devices also raise concerns about security vulnerabilities. Machine learning-based techniques have recently gained credibility in a successful application for the detection of network anomalies, including IoT networks. However, machine learning techniques cannot work without representative data. Given the scarcity of IoT datasets, the DAD emerged as an instrument for knowing the behavior of dedicated IoT-MQTT networks. This paper aims to validate the DAD dataset by applying Logistic Regression, Naive Bayes, Random Forest, AdaBoost, and Support Vector Machine to detect traffic anomalies in IoT. To obtain the best results, techniques for handling unbalanced data, feature selection, and grid search for hyperparameter optimization have been used. The experimental results show that the proposed dataset can achieve a high detection rate in all the experiments, providing the best mean accuracy of 0.99 for the tree-based models, with a low false-positive rate, ensuring effective anomaly detection.

The relative simplicity of IoT networks extends service vulnerabilities and possibilities to different network failures exhibiting system weaknesses. Therefore, having a dataset with a sufficient number of samples, labeled and with a systematic analysis, is essential in order to understand how these networks behave and detect traffic anomalies. This work presents DAD: a complete and labeled IoT dataset containing a reproduction of certain real-world behaviors as seen from the network. To approximate the dataset to a real environment, the data were obtained from a physical data center, with temperature sensors based on NFC smart passive sensor technology. Having carried out different approaches, performing mathematical modeling using time series was finally chosen. The virtual infrastructure necessary for the creation of the dataset is formed by five virtual machines, a MQTT broker and four client nodes, each of them with four sensors of the refrigeration units connected to the internal IoT network. DAD presents a seven day network activity with three types of anomalies: duplication, interception and modification on the MQTT message, spread over 5 days. Finally, a feature description is performed, so it can be used for the application of the various techniques of prediction or automatic classification.