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A comprehensive expectation identification framework for multirate time-delayed systems (2022)
Journal Article
Chen, J., Gao, J., Liu, Y., Wang, C., & Zhu, Q. (2023). A comprehensive expectation identification framework for multirate time-delayed systems. IEEE Transactions on Industrial Informatics, 19(5), 7011-7021. https://doi.org/10.1109/TII.2022.3194656

The expectation maximization (EM) algorithm has been extensively used to solve system identification problems with hidden variables. It needs to calculate a derivative equation and perform a matrix inversion in the EM-M step. The equations related to... Read More about A comprehensive expectation identification framework for multirate time-delayed systems.

Least square algorithm based on bias compensated principle for parameter estimation of canonical state space model (2022)
Journal Article
Liu, L., Long, Z., Azar, A. T., Zhu, Q., Ibraheem, I. K., & Humaidi, A. J. (2022). Least square algorithm based on bias compensated principle for parameter estimation of canonical state space model. Measurement and Control, 55(5-6), https://doi.org/10.1177/00202940211064179

Due to the existence of system noise and unknown state variables, it is difficult to realize unbiased estimation with minimum variance for the parameter estimation of canonical state space model. This paper presents a new least squares estimator base... Read More about Least square algorithm based on bias compensated principle for parameter estimation of canonical state space model.

Adaptive fixed-time neural networks control for pure-feedback non-affine nonlinear systems with state constraints (2022)
Journal Article
Li, Y., Zhu, Q., Zhang, J., & Deng, Z. (2022). Adaptive fixed-time neural networks control for pure-feedback non-affine nonlinear systems with state constraints. Entropy, 24(5), 737. https://doi.org/10.3390/e24050737

A new fixed-time adaptive neural network control strategy is designed for pure-feedback non-affine nonlinear systems with state constraints according to the feedback signal of the error system. Based on the adaptive backstepping technology, the Lyapu... Read More about Adaptive fixed-time neural networks control for pure-feedback non-affine nonlinear systems with state constraints.

Robust variable-step perturb-and-observe sliding mode controller for grid-connected wind-energy-conversion systems (2022)
Journal Article
Toumi, I., Meghni, B., Hachana, O., Azar, A. T., Boulmaiz, A., Humaidi, A. J., …Bahgaat, N. K. (in press). Robust variable-step perturb-and-observe sliding mode controller for grid-connected wind-energy-conversion systems. Entropy, 24(5), 731. https://doi.org/10.3390/e24050731

In order to extract efficient power generation, a wind turbine (WT) system requires an accurate maximum power point tracking (MPPT) technique. Therefore, a novel robust variable-step perturb-and-observe (RVS-P&O) algorithm was developed for the machi... Read More about Robust variable-step perturb-and-observe sliding mode controller for grid-connected wind-energy-conversion systems.

A new configuration of composite nonlinear feedback control for nonlinear systems with input saturation (2022)
Journal Article
Zhu, Q., Mobayen, S., Nemati, H., Zhang, J., & Wei, W. (2023). A new configuration of composite nonlinear feedback control for nonlinear systems with input saturation. Journal of Vibration and Control, 29(5-6), 1417-1430. https://doi.org/10.1177/10775463211064010

This study proposes a U-control–based Composite Nonlinear Feedback (U-CNF) design procedure. This U-CNF control establishes a double feedback loop framework for generalisation and simplification in designing the CNF control systems. Two controllers,... Read More about A new configuration of composite nonlinear feedback control for nonlinear systems with input saturation.

Multi-direction gradient iterative algorithm: A unified framework for gradient iterative and least squares algorithms (2021)
Journal Article
Chen, J., Ma, J., Gan, M., & Zhu, Q. (2022). Multi-direction gradient iterative algorithm: A unified framework for gradient iterative and least squares algorithms. IEEE Transactions on Automatic Control, 67(12), 6770-6777. https://doi.org/10.1109/TAC.2021.3132262

In this study, a multi-direction-based gradient iterative (GI) algorithm for Hammerstein systems with irregular sampling data is proposed. The algorithm updates the parameter estimates using several orthogonal directions at each iteration. The conver... Read More about Multi-direction gradient iterative algorithm: A unified framework for gradient iterative and least squares algorithms.

Disturbance-observer-based u-control (Dobuc) for nonlinear dynamic systems (2021)
Journal Article
Li, R., Zhu, Q., Yang, J., Narayan, P., & Yue, X. (2021). Disturbance-observer-based u-control (Dobuc) for nonlinear dynamic systems. Entropy, 23(12), https://doi.org/10.3390/e23121625

U-model, which is a control-oriented model set with the property of generally facilitate nonlinearity dynamic inversion/cancellation, has been introduced to the Disturbance Observer-Based control (DOBC) methods to improve the performance of the nonli... Read More about Disturbance-observer-based u-control (Dobuc) for nonlinear dynamic systems.

Complete model-free sliding mode control (CMFSMC) (2021)
Journal Article
Zhu, Q. (2021). Complete model-free sliding mode control (CMFSMC). Scientific Reports, 11(1), Article 22565. https://doi.org/10.1038/s41598-021-01871-6

This study presents a complete model-free sliding mode control (CMFSMC) framework for the control of continuous-time non-affine nonlinear dynamic systems with unknown models. The novelty lies in the introduction of two equalities to assign the deriva... Read More about Complete model-free sliding mode control (CMFSMC).

Identification and U-control of a state-space system with time-delay (2021)
Journal Article
Gu, Y., Zhu, Q., & Nouri, H. (2022). Identification and U-control of a state-space system with time-delay. International Journal of Adaptive Control and Signal Processing, 36(1), 138-154. https://doi.org/10.1002/acs.3345

This article presents a state-space model with time-delay to map the relationship between known input-output data for discrete systems. For the given input-output data, a model identification algorithm combining parameter estimation and state estimat... Read More about Identification and U-control of a state-space system with time-delay.

Robust standard gradient descent algorithm for ARX models using Aitken acceleration technique (2021)
Journal Article
Chen, J., Gan, M., Zhu, Q., Narayan, P., & Liu, Y. (2022). Robust standard gradient descent algorithm for ARX models using Aitken acceleration technique. IEEE Transactions on Cybernetics, 52(9), 9646-9655. https://doi.org/10.1109/tcyb.2021.3063113

A robust standard gradient descent (SGD) algorithm for ARX models using the Aitken acceleration method is developed. Considering that the SGD algorithm has slow convergence rates and is sensitive to the step size, a robust and accelerative SGD (RA-SG... Read More about Robust standard gradient descent algorithm for ARX models using Aitken acceleration technique.

U-model-based two-degree-of-freedom internal model control of nonlinear dynamic systems (2021)
Journal Article
Li, R., Zhu, Q., Narayan, P., Yue, A., Yao, Y., & Deng, M. (2021). U-model-based two-degree-of-freedom internal model control of nonlinear dynamic systems. Entropy, 23(2), Article 169. https://doi.org/10.3390/e23020169

This paper proposes a U-Model-Based Two-Degree-of-Freedom Internal Model Control (UTDF-IMC) structure with strength in nonlinear dynamic inversion, and separation of tracking design and robustness design. This approach can effectively accommodate mod... Read More about U-model-based two-degree-of-freedom internal model control of nonlinear dynamic systems.

Algorithms for U-model-based dynamic inversion (UM-dynamic inversion) for continuous time control systems (2020)
Journal Article
Li, R., Zhu, Q., Kiely, J., & Zhang, W. (2020). Algorithms for U-model-based dynamic inversion (UM-dynamic inversion) for continuous time control systems. Complexity, 2020, https://doi.org/10.1155/2020/3640210

To setup a universal proper user toolbox from previous individual research publications, this study generalises the algorithms for the U-model dynamic inversion based on the realisation of U-model from polynomial and state-space described continuous-... Read More about Algorithms for U-model-based dynamic inversion (UM-dynamic inversion) for continuous time control systems.

U-Model and U-Control methodology for nonlinear dynamic systems (2020)
Journal Article
Zhang, W., Zhu, Q., Mobayen, S., Yan, H., Qiu, J., & Narayan, P. (2021). U-Model and U-Control methodology for nonlinear dynamic systems. Complexity, 2020(Special issue: Learning and Adaptation for Optimization and Control of Complex Renewable Energy Systems), 1-13. https://doi.org/10.1155/2020/1050254

This study presents the fundamental concepts and technical details of a U-model-based control (U-control for short) system design framework, including U-model realisation from classic model sets, control system design procedures, and simulated showca... Read More about U-Model and U-Control methodology for nonlinear dynamic systems.

Improved gradient descent algorithms for time-delay rational state-space systems: Intelligent search method and momentum method (2020)
Journal Article
Chen, J., Zhu, Q., Hu, M., Guo, L., & Narayan, P. (2020). Improved gradient descent algorithms for time-delay rational state-space systems: Intelligent search method and momentum method. Nonlinear Dynamics, 101, 361-373. https://doi.org/10.1007/s11071-020-05755-8

This study proposes two improved gradient descent parameter estimation algorithms for rational state-space models with time-delay. These two algorithms, based on intelligent search method and momentum method, can simultaneously estimate the time-dela... Read More about Improved gradient descent algorithms for time-delay rational state-space systems: Intelligent search method and momentum method.

U-model based predictive control for nonlinear processes with input delay (2019)
Journal Article
Geng, X., Zhu, Q., Liu, T., & Na, J. (2019). U-model based predictive control for nonlinear processes with input delay. Journal of Process Control, 75, 156-170. https://doi.org/10.1016/j.jprocont.2018.12.002

In this paper, a general control scheme is proposed for nonlinear dynamic processes with input delay described by different models, including polynomial models, state-space models, nonlinear autoregressive moving average with eXogenous inputs (NARMAX... Read More about U-model based predictive control for nonlinear processes with input delay.

Adaptive finite-time stabilization of chaotic flow with a single unstable node using a nonlinear function-based global sliding mode (2018)
Journal Article
Mobayen, S., Ma, J., Pujol-Vazquez, G., Acho, L., & Zhu, Q. (2019). Adaptive finite-time stabilization of chaotic flow with a single unstable node using a nonlinear function-based global sliding mode. Iranian Journal of Science and Technology Transactions of Electrical Engineering, 43(1), 339-347. https://doi.org/10.1007/s40998-018-0153-6

© 2018, Shiraz University. This article presents a novel adaptive finite-time stabilization technique based on global sliding mode for disturbed chaotic flow with a single unstable node. The considered chaotic flow has unusual characteristics contain... Read More about Adaptive finite-time stabilization of chaotic flow with a single unstable node using a nonlinear function-based global sliding mode.

Bias compensation recursive algorithm for dual-rate rational models (2018)
Journal Article
Chen, J., Liu, Y., & Zhu, Q. (2018). Bias compensation recursive algorithm for dual-rate rational models. IET Control Theory and Applications, 12(16), 2184-2193. https://doi.org/10.1049/iet-cta.2018.5368

© The Institution of Engineering and Technology 2018. In dual-rate rational systems, some output data are missing (unmeasurable) to make the traditional recursive least squares (RLS) parameter estimation algorithms invalid. In order to overcome this... Read More about Bias compensation recursive algorithm for dual-rate rational models.

Median frequency and sum of amplitude changes in rising slope: Two potential non-invasive indicators for differentiating DU from BOO in males (2018)
Journal Article
Li, R., Gammie, A., Zhu, Q., & Nibouche, M. (2018). Median frequency and sum of amplitude changes in rising slope: Two potential non-invasive indicators for differentiating DU from BOO in males. Neurourology and Urodynamics, 37(S5), S248-S249. https://doi.org/10.1002/nau.23760

It remains a challenge to non-invasively differentiate detrusor underactivity (DU) from bladder outlet obstruction (BOO) in males, and the gold standard is pressure flow studies, which is invasive, relatively expensive and may cause bleeding and infe... Read More about Median frequency and sum of amplitude changes in rising slope: Two potential non-invasive indicators for differentiating DU from BOO in males.

Multivariate analysis of variance for maximising the diagnosing accuracy in differentiating DU from BOO in males (2018)
Journal Article
Li, R., Gammie, A., Zhu, Q., & Nibouche, M. (2018). Multivariate analysis of variance for maximising the diagnosing accuracy in differentiating DU from BOO in males. Neurourology and Urodynamics, 37(S5), S327-S328. https://doi.org/10.1002/nau.23760

Detrusor underactivity (DU) and bladder outlet obstruction (BOO) bother almost half of elder men. Although the treatment is different for these two lower urinary tract symptoms, invasive pressure flow studies remains the only gold standard for diagno... Read More about Multivariate analysis of variance for maximising the diagnosing accuracy in differentiating DU from BOO in males.

Urine flow rate shape template and intermittent flow in males (2018)
Journal Article
Li, R., Gammie, A., Zhu, Q., & Nibouche, M. (2018). Urine flow rate shape template and intermittent flow in males. Neurourology and Urodynamics, 37(S5), 1-430. https://doi.org/10.1002/nau.23760

Uroflowmetry serves as a preliminary urodynamic test for physicians to indicate the possible cause of lower urinary tract symptoms. Alongside the most researched parameter maximum flow rate (Qmax), the shape of urine flow rate curve is also reported... Read More about Urine flow rate shape template and intermittent flow in males.