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Introduction: Brain-computer interfaces (BCIs) are systems that acquire the brain's electrical activity and provide control of external devices. Since electroencephalography (EEG) is the simplest non-invasive method to capture the brain's electrical activity, EEG-based BCIs are very popular designs. Aside from classifying the extremity movements, recent BCI studies have focused on the accurate coding of the finger movements on the same hand through their classification by employing machine learning techniques. State-of-the-art studies were interested in coding five fingermovements by neglecting the brain's idle case (i.e., the state that brain is not performing any mental tasks). This may easily cause more false positives and degrade the classification performances dramatically, thus, the performance of BCIs. This study aims to propose a more realistic system to decode the movements of five fingers and the no mental task (NoMT) case from EEG signals. Methods: In this study, a novel praxis for feature extraction is utilized. Using Proper Rotational Components (PRCs) computed through Intrinsic Time Scale Decomposition (ITD), which has been successfully applied in different biomedical signals recently, features for classification are extracted. Subsequently, these features were applied to the inputs of well-known classifiers and their different implementations to discriminate between these six classes. The highest classifier performances obtained in both subject-independent and subject-dependent cases were reported. In addition, the ANOVA-based feature selection was examined to determine whether statistically significant features have an impact on the classifier performances or not. Results: As a result, the Ensemble Learning classifier achieved the highest accuracy of 55.0% among the tested classifiers, and ANOVA-based feature selection increases the performance of classifiers on five-finger movement determination in EEG-based BCI systems. Discussion: When compared with similar studies, proposed praxis achieved a modest yet significant improvement in classification performance although the number of classes was incremented by one (i.e., NoMT). [ABSTRACT FROM AUTHOR]

Artificial intelligence (AI) has gained significant traction in medical applications. This study focuses on knee joint diseases, specifically osteoarthritis (OA) and rheumatoid arthritis, which often lead to pathological gait patterns in patients due to pain and mobility issues. The proposed technique put forth in this research aims to classify gait patterns in kinematic data of osteoarthritic and asymptomatic (AS) knees. Our approach utilizes Phase Space Reconstruction (PSR), Intrinsic Time-Scale Decomposition (ITD), and neural networks to extract features. Knee kinematic data, including translations and rotations, are analyzed using ITD to obtain dominant proper rotation components (PRCs) capturing most of the energy from the signals. The phase space of PRCs is then reconstructed, revealing nonlinear gait dynamics. By employing three-dimensional PSR and Euclidean distance, we extract features that capture the distinctive dynamics of osteoarthritic and AS knee gait patterns. Utilizing neural networks, we model and classify the gait system dynamics. Experimental evaluation on 22 knee OA patients and 28 age-matched AS control individuals demonstrates the effectiveness of our method in distinguishing between the two groups' gait patterns, achieving superior classification accuracies of 92 % and 96 % , respectively. These results suggest that our approach holds promise for aiding the identification of knee OA in clinical practice, leading to improved quality outcomes. By enabling accurate identification of knee OA in clinical practice, the proposed method has the potential to contribute to improved patient outcomes, such as timely interventions, personalized treatment plans, and enhanced monitoring of disease progression. This, in turn, can lead to better management of knee OA and improved quality outcomes for patients. [ABSTRACT FROM AUTHOR]

IntroductionBrain-computer interfaces (BCIs) are systems that acquire the brain's electrical activity and provide control of external devices. Since electroencephalography (EEG) is the simplest non-invasive method to capture the brain's electrical activity, EEG-based BCIs are very popular designs. Aside from classifying the extremity movements, recent BCI studies have focused on the accurate coding of the finger movements on the same hand through their classification by employing machine learning techniques. State-of-the-art studies were interested in coding five finger movements by neglecting the brain's idle case (i.e., the state that brain is not performing any mental tasks). This may easily cause more false positives and degrade the classification performances dramatically, thus, the performance of BCIs. This study aims to propose a more realistic system to decode the movements of five fingers and the no mental task (NoMT) case from EEG signals.MethodsIn this study, a novel praxis for feature extraction is utilized. Using Proper Rotational Components (PRCs) computed through Intrinsic Time Scale Decomposition (ITD), which has been successfully applied in different biomedical signals recently, features for classification are extracted. Subsequently, these features were applied to the inputs of well-known classifiers and their different implementations to discriminate between these six classes. The highest classifier performances obtained in both subject-independent and subject-dependent cases were reported. In addition, the ANOVA-based feature selection was examined to determine whether statistically significant features have an impact on the classifier performances or not.ResultsAs a result, the Ensemble Learning classifier achieved the highest accuracy of 55.0% among the tested classifiers, and ANOVA-based feature selection increases the performance of classifiers on five-finger movement determination in EEG-based BCI systems.DiscussionWhen compared with similar studies, proposed praxis achieved a modest yet significant improvement in classification performance although the number of classes was incremented by one (i.e., NoMT).

Nowadays, cardiovascular diseases (CVD) is one of the prime causes of human mortality, which has received tremendous and elaborative research interests regarding the prevention issue. Myocardial ischemia is a kind of CVD which will lead to myocardial infarction (MI). The diagnostic criterion of MI is supplemented with clinical judgement and several electrocardiographic (ECG) or vectorcardiographic (VCG) programs. However the visual inspection of ECG or VCG signals by cardiologists is tedious, laborious and subjective. To overcome such disadvantages, numerous MI detection techniques including signal processing and artificial intelligence tools have been developed. In this study, we propose a novel technique for automatic detection of MI based on disparity of cardiac system dynamics and synthesis of the standard 12-lead and Frank XYZ leads. First, 12-lead ECG signals are synthesized with Frank XYZ leads to build a hybrid 4-dimensional cardiac vector, which is decomposed into a series of proper rotation components (PRCs) by using the intrinsic time-scale decomposition (ITD) method. The novel cardiac vector may fully reflect the pathological alterations provoked by MI and may be correlated to the disparity of cardiac system dynamics between healthy and MI subjects. ITD is employed to measure the variability of cardiac vector and the first PRCs are extracted as predominant PRCs which contain most of the cardiac vector's energy. Second, four levels discrete wavelet transform with third-order Daubechies (db3) wavelet function is employed to decompose the predominant PRCs into different frequency bands, which combines with three-dimensional phase space reconstruction to derive features. The properties associated with the cardiac system dynamics are preserved. Since the frequency components above 40 Hz are lack of use in ECG analysis, in order to reduce the feature dimension, the advisable sub-band (D4) is selected for feature acquisition. Third, neural networks are then used to model, identify and classify cardiac system dynamics between normal (healthy) and MI cardiac vector signals. The difference of cardiac system dynamics between healthy control and MI cardiac vector is computed and used for the detection of MI based on a bank of estimators. Finally, experiments are carried out on the PhysioNet PTB database to assess the effectiveness of the proposed method, in which conventional 12-lead and Frank XYZ leads ECG signal fragments from 148 patients with MI and 52 healthy controls were extracted. By using the tenfold cross-validation style, the achieved average classification accuracy is reported to be 98.20%. Results verify the effectiveness of the proposed method which can serve as a potential candidate for the automatic detection of MI in the clinical application. [ABSTRACT FROM AUTHOR]

In recent years, subsynchronous control interaction (SSCI) has frequently taken place in renewable-connected power systems. To counter this issue, utilities have been seeking tools for fast and accurate identification of SSCI events. The main challenges of SSCI monitoring are the time-varying nature and uncertain modes of SSCI events. Accordingly, this paper presents a simple but effective method that takes advantage of intrinsic time-scale decomposition (ITD). The main purpose is to improve the accuracy and robustness of ITD by incorporating the least-squares method. Results show that the proposed method strikes a good balance between dynamic performance and estimation accuracy. More importantly, the method does not require any prior information, and its performance is therefore not affected by the frequency constitution of the SSCI. Comprehensive comparative studies are conducted to demonstrate the usefulness of the method through synthetic signals, electromagnetic temporary program (EMTP) simulations, and field-recorded SSCI data. Finally, real-time simulation tests are conducted to show the feasibility of the method for real-time monitoring.

Diabetes mellitus (DM) or diabetes is an incurable, chronic, and genetic link health problem that occurs due to the higher glucose level in the blood. Continuous monitoring and automatic screening of diabetic patients will significantly improve the quality of the medical management system. DM induces cardiovascular autonomic neuropathy, which alters the morphology of electrocardiogram (ECG) signals. Hence, in this experiment, a new single-lead ECG signal database of 86 subjects (35 diabetic and 51 normal) is recorded. For the automatic screening of DM, an intrinsic time-scale decomposition (ITD) and machine learning-based framework is developed. In the first stage, denoised recorded signals are segmented into fragments of 5-s and decomposed into rotational components using the ITD algorithm. In the second stage, four features, namely, Hjorth complexity, Shannon entropy, log energy entropy, and log energy, are extracted from the ITD components. In the third stage, the Kruskal–Wallis (K–W) test is applied to select the most distinguishable features and fed to a decision tree classifier (DTC) with three different kernel functions for the automatic detection of diabetic patients. The fine tree (FT) kernel function provides the highest classification accuracy (ACC) of 86.9%. The proposed framework is developed using a 10-fold validation strategy. The developed framework is patient-centered suitable for screening in resource-limited environments and ready to be tested with more databases. [ABSTRACT FROM AUTHOR]

Fault signal of rolling bearing was easily submerged in strong background noise during actual operation, which made it difficult to identify the fault type. Aiming at these problems, a joint noise reduction method based on intrinsic time-scale decomposition (ITD) and multipoint optimal minimum entropy deconvolution adjusted (MOMEDA) was proposed, and applied to the fault diagnosis of rolling bearing. Firstly, the ITD algorithm was used to decompose the original signal of the rolling bearing fault to obtain multiple proper rotation components (PRC) ;Secondly, according to the principle of correlation coefficient and kurtosis, the PRC that had a greater correlation with the original signal was selected for reconstruction;Then, MOMEDA algorithm was used to further denoise the reconstructed signal to separate the useful signal from the noise signal. Finally, the envelope demodulation analysis of the signal was performed to extract the fault characteristic frequency and diagnose the specific location of the bearing fault. In addition, in order to verify the effectiveness of the method, the simulation signals were compared and analyzed by ITD and local mean value decomposition (LMD), MOMEDA and maximum correlation kurtosis deconvolution (MCKD), and the analysis of the outer ring instance was presented. The results indicate that the diagnosis acuracy of the joint noise reduction method based on ITD-MOMEDA is 4. 3% higher than the ITD-MCKD diagnosis accuracy, which can more effectively remove strong noise and successfully detect the type of bearing failure. [ABSTRACT FROM AUTHOR]

In a bid to solve the gyroscope temperature drift problem, a parallel denoising model based on PE-ITD and SA-ELM has been proposed in this paper, wherein, Intrinsic time-scale decomposition (ITD) is an effective signal decomposition algorithm, Permutation entropy (PE) is a entropy to accurately determine the complexity of the signal, Extreme Learning machine (ELM) is a machine learning algorithm for predicting, and Simulated Annealing(SA) for finding the optimal parameter set. First, ITD is employed to decompose the output signal of the gyroscope and the PE can distinguish the decomposition results into noise-only component, mixed component and trend component. Secondly, the mixed component is filtered by Forward liner prediction (FLP), the denoised signal can be obtained after processing. Finally, the trend component is compensated by SA-ELM, through reconstruction, the compensation result can be obtained. As is shown in experimental results, the parallel model proposed in this paper is able to effectively eliminate the temperature error compared with the traditional serial model. Compared with the EMD analysis method, the ITD is superior to the EMD analysis method in terms of computational efficiency and instantaneous information. The proposed SA-ELM algorithm takes simulated annealing algorithm to find hidden layer neurons' optimal number adaptively, which can improve the model's accuracy and generalization. This paper demonstrates the superiority of this method.

Specific emitter identification (SEI) is a technique that identifies the unique emitter from its received signal by using the specific characteristics of an emitter. In this paper, we consider an SEI problem with unknown receiver distortion. Two groups of SEI schemes based on signal decomposition are proposed. In the proposed schemes, the received signal is pre-processed by either of the following decomposition, i.e., empirical mode decomposition (EMD), intrinsic time-scale decomposition (ITD), or variational mode decomposition (VMD). In the first group of the proposed schemes, the skewness and the kurtosis are extracted from the decomposed signal, which characterize the non-Gaussian features of the signal. The support vector machine (SVM) or the back-propagation (BP) neural network is applied to fuse the features extracted from the multiple distorted receivers respectively and then determine the unknown emitter. In the second group of the proposed schemes, an approach based on the long short term memory (LSTM) is proposed. The LSTM model learns the deep features rather than the specific non-Gaussian features from the pre-processed signal. In contrast to the first group, the features used to identify the unknown emitter are extracted directly from the pre-processed signal by the trained LSTM model. Simulation results show that the proposed multi-receiver cooperative schemes can achieve the diversity gain in the identification performance. Moreover, we evaluate the identification performance of the proposed schemes in various channels, including the Gaussian channel and the fading channel. Compared to the existing methods based on different time-frequency representations, the proposed schemes possess the merits of high identification accuracy and low complexity. The significance of this paper is that the receive diversity can be achieved by the proposed schemes by using multiple distorted receivers even without compensating the receiver distortion prior to the identification. [ABSTRACT FROM AUTHOR]

The anterior cruciate ligament (ACL) possesses the function of stabilizing the knee joint through limiting anterior tibial translation and controlling tibial rotation. Patients with unilateral ACL deficiency often demonstrate alterations of knee kinematics, kinetics and gait patterns in the deficient side in comparison to the unaffected contralateral side. This also leads to the early onset of osteoarthritis. In order to detect and monitor the progression of ACL deficiency over time, various classification approaches using spatiotemporal gait variables have been presented. In this study we propose a novel method for classifying gait patterns between ACL-deficient (ACLD) knee and unaffected contralateral ACL-intact (ACLI) knee based upon gait system dynamics, intrinsic time-scale decomposition (ITD) and neural networks. First, human leg is modeled as a double-pendulum to imitate and simplify the human walking. Since the lower extremities act as a kinetic chain during dynamic tasks, control of the hip joint will interact with knee motion. Related gait kinematic parameters including knee and hip joint angle and angular velocity are decomposed into a series of proper rotation components (PRCs) and a baseline signal by using the ITD method. The first PRCs of knee and hip joint angle and angular velocity are extracted, which contain most of the kinematic signals' vibration energy and are considered to be the predominant PRCs. Third, neural networks are then used as the classifier with feature vectors as the input to distinguish between ACLD and ACLI knees based on the difference of gait system dynamics between the two groups. Finally, experiments are carried out on forty-three patients to assess the effectiveness of the proposed method. By using the leave-one-out cross-validation style under normal and fast walking speed conditions, the correct classification rates are reported to be 95.12 % and 93.28 % , respectively. In comparison to other state-of-the-art methods, the results demonstrate superior performance and the proposed method may serve as a potential assistant tool for the automatic detection of ACL deficiency in the clinical application. [ABSTRACT FROM AUTHOR]

A brain-computer interface (BCI) provides a link between the human brain and a computer. The task of discriminating four classes (left and right hands and feet) of motor imagery movements of a simple limb-based BCI is still challenging because most imaginary movements in the motor cortex have close spatial representations. We aimed to classify binary limb movements, rather than the direction of movement within one limb. We also investigated joint time-frequency methods to improve classification accuracies. Neither of these, to our knowledge, has been investigated previously in BCI. We recorded EEG data from eleven participants, and demonstrated the classification of four classes of simple-limb motor imagery with an accuracy of 91.46% using intrinsic time-scale decomposition and 88.99% using empirical mode decomposition. In binary classifications, we achieved average accuracies of 89.90% when classifying imaginary movements of left hand versus right hand, 93.1% for left hand versus right foot, 94.00% for left hand versus left foot, 83.82% for left foot versus right foot, 97.62% for right hand versus left foot, and 95.11% for right hand versus right foot. The results show that the binary classification performance is slightly better than that of four-class classification. Our results also show that there is no significant difference in terms of spatial distribution between left and right foot motor imagery movements. There is also no difference in classification performances involving left or right foot movement. This work demonstrates that binary and four-class movements of the left and right feet and hands can be classified using recorded EEG signals of the motor cortex, and an intrinsic time-scale decomposition (ITD) feature extraction method can be used for real time brain computer interface. [ABSTRACT FROM AUTHOR]

Extraction of the weak fault features under strong background noise is crucial to early fault diagnosis in rolling bearings. However, these fault features (i.e., impulse components) in vibration signals are always submerged and distorted by heavy noise in the early fault phase. Thus, a new method called intrinsic time-scale decomposition (ITD)-based sparse coding shrinkage (SCS) (named ITD-SCS) is proposed as a sparse representation for impulse component extraction from bearing vibration signals. ITD can decompose the signal into a set of proper rotations (PRs) to enable impulse components as prominent as possible. Singular value decomposition (SVD) as the noise prefilter processing of SCS enables the preserved singular values to persist the sparsity of PRs. Finally, ITD-SCS uses SCS to extract the most important impulse components in the reconstruction signal. Thus, ITD-SCS integrates ITD, SVD, and SCS effectively based on their own characteristics for periodic impact extraction. The experimental results on the simulation signals and vibration signals collected from rolling bearings indicate that ITD-SCS is effective for extracting the weak fault features and performs well for bearing fault diagnosis. [ABSTRACT FROM AUTHOR]

The QRS complex recorded from the surface electrocardiogram (ECG) arises from electrical activation of the ventricular myocardium through the normal conduction system. The presence of a fragmented QRS (fQRS) complex reflects abnormal electrical activation and has been recently shown to identify patients with heart disease at risk of sudden cardiac death (SCD). The evaluation of fQRS is currently performed qualitatively by visual inspection which can be time consuming and subject to interpretation. Moreover, qualitative assessment of QRS for fragmentation may be insensitive to more subtle deflections in the QRS complex that may be equally prognostic. This study proposes an automated method to quantify QRS fractionation using intrinsic time-scale decomposition (ITD). Instantaneous morphology features are extracted from the decomposed QRS signal to index variations in its shapes. Our quantitative fQRS metric was found to be significantly greater in QRS complexes with fragmentation compared to normal QRS complexes derived from real-world ECGs in the Physikalisch-Technische Bundesanstalt (PTB) database. ROC analysis showed an area under the curve of 0.96 when fQRS was quantified from the precordial ECG leads, V1–V6. Thus, quantification of fQRS using the proposed ITD-based method can accurately identify fQRS. Our approach shows tremendous potential and could be investigated further for SCD risk assessment in patients with heart disease by improving the identification of fQRS that may or may not be visually apparent. [ABSTRACT FROM AUTHOR]

Attention deficit hyperactivity disorder (ADHD), a neuro-developmental condition, is characterized by various degrees of impulsivity, hyperactivity, and inattention. Treatment of this condition and minimizing its negative impact on learning, working, forming relationships, and quality of life depends heavily on the early identification. The Electroencephalography (EEG) is a useful neuroimaging technique for understanding ADHD. This study examines the brain activity of children with ADHD by analyzing the EEG signals using the intrinsic time-scale decomposition (ITD). Different combinations of the modes, known as Proper Rotation Components (PRCs), produced by ITD, are used to extract a variety of connectivity-based features (magnitude square coherence, cross power spectral density, correlation coefficient, covariance, cohentropy coefficient, correntropy coefficient). EEG signals of 15 ADHD children and 18 age-matched health children are recorded while resting with the eyes closed. Mentioned features are calculated using different channel pairs chosen from longitudinal and transversal planes. Through various machine learning approaches and a 10-fold cross-validation method, the proposed approach is evaluated to distinguish between ADHD patients and healthy controls. Classification accuracies are obtained for the longitudinal and transverse planes, between 92.90% to 99.90% and 91.70% to 100.00%, respectively. Our results support the remarkable performance of the proposed approach, and represent a substantial advance over similar studies in terms of recognizing and classifying ADHD. • Classification of ADHD EEG signals using ITD and connectivity-based feature extraction. • Modes produced by ITD are used to compute connectivity features. • Combinations of modes in longitudinal and transversal planes are used for feature extraction. • Highest accuracies for longitudinal and transverse planes are 99.90% and 100.00%, respectively. • Results represent a significant improvement over previous studies. [ABSTRACT FROM AUTHOR]