Article
Engineering, Biomedical
Haidong Gu, Chun-An Chou
Summary: A non-uniform multivariate multiscale entropy method has been developed to better assess the complexity of multivariate complex systems. Experimental results demonstrate that this method outperforms traditional approaches and may be applied for critical transition detection and pattern recognition.
BIOMEDICAL SIGNAL PROCESSING AND CONTROL
(2022)
Article
Computer Science, Information Systems
Yuan-Lun Hsieh, Maysam F. Abbod
Summary: The study analyzed gait data and ground reaction force to find that patients with Parkinson's disease have a higher Complexity Index (CI) compared to healthy controls, and dual-task actions may affect gait and cognitive function. This change suggests that when individuals face pathology or stress, CI may increase first and decrease afterwards.
Article
Engineering, Electrical & Electronic
Abhijit Bhattacharyya, Rajesh Kumar Tripathy, Lalit Garg, Ram Bilas Pachori
Summary: This study introduces a novel multivariate-multiscale approach for computing spectral and temporal entropies from multichannel EEG signals to recognize human emotions. The proposed method shows promising results in emotion classification accuracy.
IEEE SENSORS JOURNAL
(2021)
Article
Chemistry, Analytical
Stefano Filippo Castiglia, Dante Trabassi, Carmela Conte, Alberto Ranavolo, Gianluca Coppola, Gabriele Sebastianelli, Chiara Abagnale, Francesca Barone, Federico Bighiani, Roberto De Icco, Cristina Tassorelli, Mariano Serrao
Summary: The aim of this study was to assess the ability of MSE, RCMSE, and CI to characterize gait complexity in subjects with Parkinson's disease and healthy subjects. Trunk acceleration patterns were acquired and analyzed, and these measures were found to differentiate Parkinson's disease patients from healthy subjects and were correlated with motor disability and other factors. A scale factor of 4 or 5 in the MSE procedure yielded the best trade-off in terms of post-test probabilities for detecting gait variability and complexity in Parkinson's disease.
Article
Physics, Multidisciplinary
Hongjian Xiao, Danilo P. Mandic
Summary: Entropy-based methods are important in quantifying the complexity of real-world systems. We propose a new method called veMSE, which can robustly evaluate structural complexity even with shorter data. veMSE also exhibits desirable properties such as robustness to embedding dimension and noise resilience.
Article
Engineering, Biomedical
Evangelos Kafantaris, Tsz-Yan Milly Lo, Javier Escudero
Summary: Multivariate entropy quantification algorithms are important tools for extracting information from multi-channel physiological time-series. However, certain channels may overshadow others, resulting in information loss. This study introduces the framework of Stratified Entropy to prioritize channels based on their allocation to respective strata, leading to a richer description of the time-series. Variations of the algorithm are successfully applied to different types of time-series, demonstrating improved discrimination capacity and the potential for utilizing prior knowledge.
IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING
(2023)
Article
Physics, Multidisciplinary
Han-Ping Huang, Chang Francis Hsu, Yi-Chih Mao, Long Hsu, Sien Chi
Summary: This study explores the relationship between entropy values and gait stability, finding that the average entropy (AE) can accurately differentiate between healthy and diseased individuals. The results show the potential of AE as a measure of gait stability.
Article
Mathematics, Interdisciplinary Applications
Zhuo Wang, Pengjian Shang
Summary: Researchers have proposed three generalized entropy plane methods for evaluating the complexity of two-dimensional data, analyzed their performance, and applied them to the study of multivariate stock time series. The complexity-entropy causality plane method showed good performance, and multiscale multivariate dispersion entropy method was also proposed.
CHAOS SOLITONS & FRACTALS
(2021)
Article
Mathematics, Interdisciplinary Applications
Bhabesh Deka, Dipen Deka
Summary: The assessment of dynamical complexity is vital in various fields such as medical diagnostics, mechanical system fault analysis, and astrophysics. Traditional entropy measures are limited by short data length and sensitive predetermined parameters. Distribution entropy (DistEn) is a robust complexity estimator, but it fails to distinguish noise and chaotic signals while underestimating their complexity at higher scales. To overcome these limitations, an improved distribution entropy (ImDistEn) is proposed, which utilizes embedded vectors' orientation, ordinality, and l(1)-norm distance information. Simulation results demonstrate that ImDistEn can accurately assess the complexity of different types of signals.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Mathematics, Interdisciplinary Applications
Boyi Zhang, Pengjian Shang, Qin Zhou
Summary: The paper introduces multivariate fractional dispersion entropy (MMFDE) and MMFDE plane to study the structural complexity of multivariate nonlinear systems, successfully identifying chaotic and fractional order chaotic systems, as well as demonstrating practical value in financial time series and epileptic EEG recordings.
CHAOS SOLITONS & FRACTALS
(2021)
Article
Physiology
Herbert F. Jelinek, Rohisha Tuladhar, Garland Culbreth, Gyanendra Bohara, David Cornforth, Bruce. J. West, Paolo Grigolini
Summary: The study emphasizes the importance of crucial events in physiological dynamics, where they are defined as short-term turbulence phenomena with waiting time distribution density. The index of the distribution determines the stability of the process, with healthy physiological processes being closer to the non-stationary regime. Disease progression is observed to shift the IPL index towards Gaussian statistics, providing a new index for assessing disease severity.
FRONTIERS IN PHYSIOLOGY
(2021)
Article
Mathematics, Interdisciplinary Applications
Yu Wang, Pengjian Shang
Summary: An improved new model, mvMDE, and its fractional order form, GmvMDE, are proposed based on multivariate multiscale dispersion entropy theories. These models effectively measure and distinguish sequence complexity, with GmvMDE better capturing small sequence evolutions. Additionally, MSDE and GMSDE models are introduced to accurately capture systemic complexity of financial portfolios.
FRACTALS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY
(2021)
Article
Computer Science, Information Systems
Si Thu Aung, Yodchanan Wongsawat
Summary: This paper introduces a new method called M-mDistEn for detecting motion artifacts in EEG signals, demonstrating high accuracy and statistical significance in differentiating noisy and clean signal portions.
Article
Behavioral Sciences
Monika Lewandowska, Krzysztof Tolpa, Jacek Rogala, Tomasz Piotrowski, Joanna Dreszer
Summary: This study aimed to investigate the changes in complexity of resting-state EEG over time and space. The study used multivariate Multiscale Entropy (mMSE) to analyze the rsEEG complexity and examine its sex/gender differences in 95 healthy adults. The results showed that the channel sets corresponding to the somatomotor, dorsolateral network, and default mode had the highest complexity, while the visual network, limbic network, and frontoparietal network had the lowest complexity. Women showed higher complexity change and differences in entropy at different scales compared to men.
BEHAVIORAL AND BRAIN FUNCTIONS
(2023)
Article
Engineering, Electrical & Electronic
Zhenzhen Jin, Yulong Xiao, Deqiang He, Zexian Wei, Yingqian Sun, Weifeng Yang
Summary: As one of the key components of the train, the condition of the bearing is crucial to ensure its safe operation. However, the vibration signal of the bearing is often nonlinear and nonstationary, making it difficult to extract fault features and resulting in low diagnostic accuracy. This study proposes a bearing fault diagnosis method based on refined piecewise composite multivariate multiscale fuzzy entropy (RPCMMFE) and convolutional neural network (CNN) to overcome these challenges. Experimental results demonstrate that the proposed method improves the stability and discrimination ability of the extracted features, leading to more accurate bearing fault identification with average accuracy rates of 99% and 99.17%, respectively. (c) 2022 Elsevier Inc. All rights reserved.
DIGITAL SIGNAL PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Qiang Gao, Guodong Yin, Charlie C. L. Wang, Wei-Hsin Liao
Summary: This paper presents a novel structure of multi-cell tube filled with auxetic structures to improve crashworthiness performances. Finite element analysis and experimental validation are conducted to investigate the energy absorbing performances of these tubes. The results show that the multi-cell tubes with auxetic structures have better energy absorption performance compared to other typical energy absorbers. Parametric study reveals that tube and beam thicknesses and beam angles significantly affect the energy absorbing performances. An analytical model is established to accurately predict the energy absorption performances of the proposed structures under axial impact loadings.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2023)
Article
Automation & Control Systems
Yiheng Wei, YangQuan Chen, Yingdong Wei, Xuan Zhao
Summary: This paper investigates the stability analysis issue of nabla tempered fractional order systems for the first time. It defines the (discrete time) tempered Mittag-Leffler stability and derives a stability criterion using the Lyapunov method. Additionally, boundedness and attractiveness are also investigated.
ASIAN JOURNAL OF CONTROL
(2023)
Article
Thermodynamics
Zhenlong Wu, Yanhong Liu, Donghai Li, YangQuan Chen
Summary: This paper proposes a multivariable active disturbance rejection control (ADRC) for a compression liquid chiller system, where the loop coupling is estimated and compensated in real-time by enhanced reduced-order extended state observer (ESO) and static decoupling. The simulation results illustrate that the proposed control strategy can guarantee satisfactory tracking performance and estimate the loop coupling completely under different operating conditions. Compared with the decentralized regular ADRC, the performance of the loop coupling rejection and the fluctuation of the control signal have improved significantly.
Article
Materials Science, Multidisciplinary
Ying Zhang, Wei-Hsin Liao, Chris Bowen, Wei Wang, Junyi Cao
Summary: This paper presents new insights into the accuracy and application constraints of modeling methods for calculating the impact of magnetic force on multi-stable energy harvesters. Through theoretical derivation and numerical evaluation, a quantitative assessment of errors under different structural parameters and magnet sizes is provided. Experimental measurements are also conducted to verify the applicability of these modeling methods.
JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES
(2023)
Article
Biotechnology & Applied Microbiology
Li Zou, Kisum Chu, Xuan He, Ye Li, Liangbin Zhou, Xiayi Xu, Wei-Hsin Liao, Ling Qin
Summary: The study aims to develop a novel hybrid therapeutic device that integrates low-level laser therapy, heat therapy, and local massage therapy for knee osteoarthritis (KOA) treatment. The CUHK-OA-M2 device effectively provides relief from clinical symptoms for KOA patients. The pilot test showed significant decrease in WOMAC scores after two treatment periods, indicating the therapeutic significance of the device.
BIOENGINEERING-BASEL
(2023)
Article
Physics, Applied
Shitong Fang, Keyu Chen, Zhihui Lai, Shengxi Zhou, Wei-Hsin Liao
Summary: This study presents a snap-through energy harvester to overcome the energy output bottleneck of ultra-low-frequency (<1 Hz) rotational energy harvesting. The integration of a buckled mechanism and hierarchical auxetic structures enables enhanced power output and reduces the natural frequency of the system. Experimental results demonstrate a significant improvement in output power, making the proposed harvester suitable for low-power sensors and structural health monitoring of wind turbine blades at ultra-low rotational frequencies.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Juntong Xing, Masoud Rezaei, Huliang Dai, Wei-Hsin Liao
Summary: This Letter examines the potential impact of different surface protrusions on galloping energy harvesters. Three types of protruded bluff bodies with rectangular, triangular, and elliptical metasurfaces are proposed, and four surface treatments are used to modify their protruded shape. Wind tunnel experiments show that the protrusions can significantly alter the oscillation mode, and only backward protrusions can enhance the galloping response. Both experiments and simulations indicate that elliptical surface protrusions have the greatest potential to improve the galloping energy harvesting performance. Specifically, with a backward protruded length of 15 mm, the maximum output power in experiments is measured at 0.757 mW, occurring at 5.1 m/s and an optimal load resistance of 300 k?. In this case, the energy harvester outperforms its counterpart carrying a simple square prism by 157.48%.
APPLIED PHYSICS LETTERS
(2023)
Article
Mathematics, Interdisciplinary Applications
Yiheng Wei, Xuan Zhao, Yingdong Wei, Yangquan Chen
Summary: This paper investigates the stability analysis problem for a class of incommensurate nabla fractional order systems, considering both Caputo definition and Riemann-Liouville definition. Several elementary fractional difference inequalities on Lyapunov functions are developed under the convex assumption. By utilizing the essential features of nabla fractional calculus, sufficient conditions are given to guarantee the asymptotic stability of the incommensurate system using the direct Lyapunov method. Four examples are provided to substantiate the efficacy and effectiveness of the theoretical results.
JOURNAL OF SYSTEMS SCIENCE & COMPLEXITY
(2023)
Article
Mathematics, Applied
Weiyuan Ma, Nuri Ma, Changping Dai, YangQuan Chen, Xinwei Wang
Summary: As the COVID-19 mutates, the infection rate is increasing rapidly and the vaccine is ineffective against the mutated strain. This paper proposes a SEIR-type fractional model with reinfection and vaccine inefficacy, which successfully captures the dynamics of the mutated COVID-19 pandemic. The model's existence, uniqueness, boundedness, and nonnegativeness are derived, and the local and global stability based on the basic reproduction number R0 are analyzed. Sensitivity analysis evaluates the impact of each parameter on R0 and ranks key epidemiological parameters. Additionally, necessary conditions for implementing fractional optimal control and corresponding optimal solutions for mitigating COVID-19 transmission are obtained.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2023)
Article
Engineering, Mechanical
Ying Zhang, Qinghua Liu, Yaguo Lei, Junyi Cao, Wei-Hsin Liao
Summary: This paper proposes a compact magnetic Halbach high negative stiffness isolator to improve low-frequency isolation performance in high static support occasions by reducing size and weight. The magnetic stiffness model is derived and the dynamic equation is established to investigate the transmissibility for different magnetic arrays. Numerical and experimental results demonstrate the effectiveness of the proposed isolator under low-frequency and random excitations.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Instruments & Instrumentation
Keyu Chen, Shitong Fang, Zhihui Lai, Junyi Cao, Wei-Hsin Liao
Summary: In this research, a plucking REH with auxetic structures is proposed to enhance the power output of rotational energy harvesting under low-rotational-frequency excitations, using frequency up-conversion and auxetic structures. Finite element simulation is conducted to analyze the performance of the proposed REH, and the simulation results match well with the experimental ones. The maximum power output of the APREH is found to be 1.43 mW at 1.1 Hz, increased by 686% compared with the conventional plain plucking REH.
SMART MATERIALS AND STRUCTURES
(2023)
Article
Instruments & Instrumentation
Gaoyu Liu, Hongpeng Liao, Xuan Zhao, Wei-Hsin Liao, Junyi Cao
Summary: Robot-assisted minimally invasive surgery allows surgeons to perform complex surgical operations with less damage and pain. A new tactile display device based on MR fluid is proposed, which overcomes the major drawbacks of existing devices and provides various sensations to human fingers.
SMART MATERIALS AND STRUCTURES
(2023)
Article
Biology
Junxiao Xie, Huan Zhao, Junyi Cao, Qiumin Qu, Hongmei Cao, Wei-Hsin Liao, Yaguo Lei, Linchuan Guo
Summary: In order to improve the effectiveness of clinical diagnosis, a wearable multisource gait monitoring system is developed to quantify gait abnormalities in patients with Parkinson's disease (PD). The system integrates force sensitive sensors, piezoelectric sensors, and inertial measurement units to collect and transmit gait data. Features extracted from each type of data can quantify the health status of the subjects and the validity of multisource gait data is verified. This system has potential in gait analysis and objective evaluation of PD.
COMPUTERS IN BIOLOGY AND MEDICINE
(2023)
Article
Engineering, Mechanical
Guoyuan Xia, Qitao Lu, Mingjing Cai, Xin Li, Daxing Zhang, Congsi Wang, Wei-Hsin Liao
Summary: This paper proposes an adaptive kinetic energy reallocation (AKER) mechanism to stabilize the output power of wearable energy harvesters. The AKER manipulates the kinetic energy transfer to enhance system response, thereby achieving power stability.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2024)
