User-specific Patterns Research Articles

Statistical Predictive Hybrid Choice Modeling: Exploring Embedded Neural Architecture

This study introduces an enhanced version of the discrete choice model combining embedded neural architecture to enhance predictive accuracy while preserving interpretability in choice modeling across temporal dimensions. Unlike the traditional architectures, which directly utilize raw data without intermediary transformations, this study introduces a modified approach incorporating temporal embeddings for improved predictive performance. Leveraging the Phones Accelerometer dataset, the model excels in predictive accuracy, discrimination capability and robustness, outperforming traditional benchmarks. With intricate parameter estimates capturing spatial orientations and user-specific patterns, the model offers enhanced interpretability. Additionally, the model exhibits remarkable computational efficiency, minimizing training time and memory usage while ensuring competitive inference speed. Domain-specific considerations affirm its predictive accuracy across different datasets. Overall, the subject model emerges as a transparent, comprehensible, and powerful tool for deciphering accelerometer data and predicting user activities in real-world applications.

Securing Internet-of-Medical-Things networks using cancellable ECG recognition

Reinforcement of the Internet of Medical Things (IoMT) network security has become extremely significant as these networks enable both patients and healthcare providers to communicate with each other by exchanging medical signals, data, and vital reports in a safe way. To ensure the safe transmission of sensitive information, robust and secure access mechanisms are paramount. Vulnerabilities in these networks, particularly at the access points, could expose patients to significant risks. Among the possible security measures, biometric authentication is becoming a more feasible choice, with a focus on leveraging regularly-monitored biomedical signals like Electrocardiogram (ECG) signals due to their unique characteristics. A notable challenge within all biometric authentication systems is the risk of losing original biometric traits, if hackers successfully compromise the biometric template storage space. Current research endorses replacement of the original biometrics used in access control with cancellable templates. These are produced using encryption or non-invertible transformation, which improves security by enabling the biometric templates to be changed in case an unwanted access is detected. This study presents a comprehensive framework for ECG-based recognition with cancellable templates. This framework may be used for accessing IoMT networks. An innovative methodology is introduced through non-invertible modification of ECG signals using blind signal separation and lightweight encryption. The basic idea here depends on the assumption that if the ECG signal and an auxiliary audio signal for the same person are subjected to a separation algorithm, the algorithm will yield two uncorrelated components through the minimization of a correlation cost function. Hence, the obtained outputs from the separation algorithm will be distorted versions of the ECG as well as the audio signals. The distorted versions of the ECG signals can be treated with a lightweight encryption stage and used as cancellable templates. Security enhancement is achieved through the utilization of the lightweight encryption stage based on a user-specific pattern and XOR operation, thereby reducing the processing burden associated with conventional encryption methods. The proposed framework efficacy is demonstrated through its application on the ECG-ID and MIT-BIH datasets, yielding promising results. The experimental evaluation reveals an Equal Error Rate (EER) of 0.134 on the ECG-ID dataset and 0.4 on the MIT-BIH dataset, alongside an exceptionally large Area under the Receiver Operating Characteristic curve (AROC) of 99.96% for both datasets. These results underscore the framework potential in securing IoMT networks through cancellable biometrics, offering a hybrid security model that combines the strengths of non-invertible transformations and lightweight encryption.

Personalized Feature Importance Ranking for Affect Recognition From Behavioral and Physiological Data

Designing affect-based personalized technology involves dealing with large datasets. Machine learning (ML) algorithms are employed to predict affect and similar human factors from in-game metrics, behavioral patterns, or physiological responses. The classification performance is usually presented as a global point estimate without providing user-specific interpretations. This approach is incompatible with effective personalization in games because it disregards the variability of body responses between players. This paper proposes a methodology to classify subjective human factors from large multimodal data. A public VR dataset (CEAP-360VR) was used to extensively compare three ML classifiers and five feature importance techniques. The produced models could reduce the original feature space by 82% (from 113 to 20 features) without compromising predictive performance (F1 score). A random forest (RF) using forward sequential feature selection (fSFS) yielded the best prediction of binary valence (F1=0.761) and arousal (F1=0.748). Finally, feature importance rankings are discussed with emphasis on global and user-specific patterns that may improve affect recognition. The proposed methodology is envisioned to help game designers and researchers create customized user-centric games and VR experiences inferring possible explanations from multimodal datasets.

Security enhancement of the access control scheme in IoMT applications based on fuzzy logic processing and lightweight encryption

Security of Internet-of-Medical-Things (IoMT) networks has evolved as a vital issue in recent years. The IoMT networks are designed to link patients with caregivers. All reports, data, and medical signals are transferred over these networks. Hence, these networks require robust and secure access strategies for patients to send their vital data or reports. Hence, hacking of these networks may lead to harmful effects on patients. One of the vulnerable points to hacking in these networks is the access point. Access to these networks could be performed with biometrics. The popular biometric traits for this purpose are biomedical signals such as Electrocardiogram (ECG) signals, as they are continuously monitored and measured for patients. A common thread between all biometric authentication systems is the possibility of losing the biometric traits forever if hacking attempts manage to concur the biometric template storage. A new trend in the field of biometric authentication is to avoid the utilization of original biometrics in access control processes. A possible alternative is to use cancelable biometrics instead. Cancelable biometrics can be generated through encryption schemes or non-invertible transforms. This paper adopts both strategies in a unified framework for cancelable ECG signal recognition that can be used in the access step of IoMT networks. The proposed framework begins with applying a non-invertible transformation on the ECG signals through fuzzy logic to change the dynamic range of the signals. As this process is non-invertible in nature, it prevents the recovery of the original ECG signals from the processed versions, which is the main target of cancelable biometric systems. After that, lightweight encryption through XOR operation with user-specific patterns is implemented. Here, the high complexity of full encryption schemes that need a large processing burden is eliminated. The addition of the encryption stage enhances the security of cancelable biometric traits, allowing a hybrid nature of the proposed cancelable biometric framework through the merging of non-invertible transforms and encryption algorithms. Moreover, an FPGA hardware implementation is introduced for real implementation of the proposed ECG-based cancelable biometric recognition framework. This hardware can accompany the user to allow access of the IoMT network when requested. Experimental results show a promising performance of the proposed framework with a large Area under the Receiver Operating Characteristic curve (AROC) of 99.5% and an Equal Error Rate (EER) of 0.058%.

Cancelable HD-SEMG Biometric Identification via Deep Feature Learning.

Conventional biometric modalities, such as the face, fingerprint, and iris, are vulnerable against imitation and circumvention. Accordingly, secure biometric modalities with cancelable properties are needed for personal identification, especially in smart healthcare applications. Here we developed a person identification model using high-density surface electromyography (HD-sEMG) as biometric traits. In this model, the HD-sEMG biometric templates are cancelable and could be customized by the users through finger isometric contractions. A deep feature learning approach, implemented by convolutional neural networks (CNNs) is used to capture user-specific patterns from HD-sEMG signals and make identification decisions. This model has been validated on twenty-two subjects, with training and testing data acquired from two different days. The rank-1 identification accuracy and equal error rate for 44 identities (22 subjects × 2 accounts) can reach 87.23% and 4.66%, respectively. The cross-day identification accuracy of the proposed model is higher than the results of previous methods reported in the literature. The usability and efficiency of the proposed model are also investigated, indicating its potentials for practical applications.

Electrohydrodynamic printing of sub-microscale fibrous architectures with improved cell adhesion capacity

ABSTRACT A solution-based electrohydrodynamic (EHD) printing strategy was developed to fabricate sub-microscale biopolymeric fibres to mimic the tiny architectures of native extracellular matrix (ECM) for enhanced cellular performance. It was found that when the working voltage was significantly reduced to 500 V, sub-microscale fibres as well as user-specific patterns with an average fibre size of 193 ± 51 nm can be stably EHD printed. The presented process is applicable to biocompatible polycaprolactone (PCL) for the fabrication of water-stable sub-microscale fibrous architectures. The resultant sub-microscale fibres exhibited unique capability to enhance cellular adhesion, spreading and orientation in comparison with conventional microscale fibres fabricated by conventional melt-based EHD printing. The EHD-printed fibres can be precisely stacked to form multilayer sub-microscale structures. The proposed solution-based EHD printing process provides a promising strategy to fabricate sub-microscale biopolymeric architectures that could be further functionalised by the incorporation of bioactive components for enhanced tissue regeneration.

Application of artificial bee colony algorithm in feature optimization for motor imagery EEG classification

Motor imagery (MI) tasks evoke event-related desynchronization (ERD) and synchronization (ERS); the ERD-/ERS-related features appearing at specific channels are frequency and time localized. Therefore, optimal channels, frequency band and time interval are of great significance for MI electroencephalography feature extraction. In this paper, channel selection method based on linear discriminant criteria is used to automatically select the channels with high discriminative powers. In addition, the concept of artificial bee colony algorithm is first introduced to find the global optimal combination of frequency band and time interval simultaneously without prior knowledge for common spatial pattern features extraction and classification. Experimental results demonstrate that this scheme can adapt to user-specific patterns and find the relatively optimal channels, frequency band and time interval for feature extraction. The classification results on the BCI Competition III Dataset IVa and BCI Competition IV Dataset IIa clearly present the effectiveness of the proposed method outperforming most of the other competing methods in the literature.

Privacy Protection of Node Location and Data in Wireless Sensor Networks

In order to solve the problem of low safety and low efficiency in distributed data protection in wireless sensor networks, a new method for privacy protection of node location and data in wireless sensor networks is researched in this paper. The author develops a novel architectural framework that observes user-specific patterns to distinguish between legitimate users and illegitimate user’s thus enhancing and strengthening user authentication. An engine that calculates the authentication score (the similarity of features of the past and recent behaviors) for a given user is proposed. Simulation results show that the proposed method can improve overall system performance substantially.

Micro/nanoscale electrohydrodynamic printing: from 2D to 3D

Electrohydrodynamic printing (EHDP), based on the electrohydrodynamically induced flow of materials, enables the production of micro/nanoscale fibers or droplets and has recently attracted extensive interest to fabricate user-specific patterns in a controlled and high-efficiency manner. However, most of the existing EHDP techniques can only print two-dimensional (2D) micropatterns which cannot meet the increasing demands for the direct fabrication of three-dimensional (3D) microdevices. The integration of EHDP techniques with the layer-by-layer stacking principle of additive manufacturing has emerged as a promising solution to this limitation. Here we present a state-of-the-art review on the translation of 2D EHDP technique into a viable micro/nanoscale 3D printing strategy. The working principle, essential components as well as critical process parameters for EHDP are discussed. We highlight recent explorations on both solution-based and melt-based 3D EHDP techniques in cone-jet and microdripping modes for the fabrication of multimaterial structures, microelectronics and biological constructs. Finally, we discuss the major challenges as well as possible solutions with regard to translating the 3D EHDP process into a real micro/nanoscale additive manufacturing strategy for the freeform fabrication of 3D structures.

Interactive Learning of Pattern Rankings

Pattern mining provides useful tools for exploratory data analysis. Numerous efficient algorithms exist that are able to discover various types of patterns in large datasets. Unfortunately, the problem of identifying patterns that are genuinely interesting to a particular user remains challenging. Current approaches generally require considerable data mining expertise or effort from the data analyst, and hence cannot be used by typical domain experts. To address this, we introduce a generic framework for interactive learning of userspecific pattern ranking functions. The user is only asked to rank small sets of patterns, while a ranking function is inferred from this feedback by preference learning techniques. Moreover, we propose a number of active learning heuristics to minimize the effort required from the user, while ensuring that accurate rankings are obtained. We show how the learned ranking functions can be used to mine new, more interesting patterns. We demonstrate two concrete instances of our framework for two different pattern mining tasks, frequent itemset mining and subgroup discovery. We empirically evaluate the capacity of the algorithm to learn pattern rankings by emulating users. Experiments demonstrate that the system is able to learn accurate rankings, and that the active learning heuristics help reduce the required user effort. Furthermore, using the learned ranking functions as search heuristics allows discovering patterns of higher quality than those in the initial set. This shows that machine learning techniques in general, and active preference learning in particular, are promising building blocks for interactive data mining systems.

EEG-basierte Brain-Computer Interfaces zur Echtzeit-Dekodierung mentaler Zustände

Brain-computer interfaces (BCI) employ algorithmic procedures of machine learning in order to extract user-specific patterns of high-dimensional EEG features. These patterns are optimised to decode intention-related brain states in real-time. Characteristic BCI applications for paralysed patients are control of active prostheses or speller software. To recognise a user’s motor intention a BCI system utilises individual EEG activation indices, such as the readiness potential or the modulation of regional EEG rhythms. Also beyond the borders of rehabilitation, this neurotechnology enables a growing set of novel application scenarios, e. g., BCIs can serve as optimised feedback tools for the stabilisation of mental states such as vigilance or attention.