Explore the vast range of titles available.

Offshore platforms are widely used to explore, drill, produce, storage, and transport ocean resources and are usually subject to environmental loading, such as waves, winds, ice, and currents, which may lead to failure of deck facilities, fatigue failure of platforms, inefficiency of operation, and even discomfort of crews. In order to ensure reliability and safety of offshore platforms, it is of great significance to explore a proper way of suppressing vibration of offshore platforms. There are mainly three types of control schemes, i.e., passive control schemes, semi-active control schemes, and active control schemes, to deal with vibration of offshore platforms. This paper provides an overview of these schemes. Firstly, passive control schemes and several semi-active control schemes are briefly summarized. Secondly, some classical active control approaches, such as optimal control, robust control, and intelligent control, are briefly reviewed. Thirdly, recent advances of active control schemes with delayed feedback control, sliding model control, sampled-data control, and network-based control are deeply analyzed. Finally, some challenging issues are provided to guide future research directions.

Since the early ages of human existence on Earth, humans have fought against natural hazards for survival. Over time, the most dangerous hazards humanity has faced are earthquakes and strong winds. Since then and till nowadays, the challenges are ongoing to construct higher buildings that can withstand the forces of nature. This paper is a detailed review of various vibration control strategies used to enhance the dynamical response of high-rise buildings. Hence, different control strategies studied and used in civil engineering are presented with illustrations of real applications if existing. The main aim of this review paper is to provide a reference-rich document for all the contributors to the vibration control of structures. This paper will clarify the applicability of specific control strategies for high-rise buildings. It is worth noting that not all the studied and investigated methods are applicable to high-rise buildings; a few of them remain limited by many parameters such as cost-effectiveness and engineering-wise installation and maintenance.

Fluid-conveying pipes are widely used to transfer bulk fluids from one point to another in many engineering applications. They are subject to various excitations from the conveying fluids, the supporting structures, and the working environment, and thus are prone to vibrations such as flow-induced vibrations and acoustic-induced vibrations. Vibrations can generate variable dynamic stress and large deformation on fluid-conveying pipes, leading to vibration-induced fatigue and damage on the pipes, or even leading to failure of the entire piping system and catastrophic accidents. Therefore, the vibration control of fluid-conveying pipes is essential to ensure the integrity and safety of pipeline systems, and has attracted considerable attention from both researchers and engineers. The present paper aims to provide an extensive review of the state-of-the-art research on the vibration control of fluid-conveying pipes. The vibration analysis of fluid-conveying pipes is briefly discussed to show some key issues involved in the vibration analysis. Then, the research progress on the vibration control of fluid-conveying pipes is reviewed from four aspects in terms of passive control, active vibration control, semi-active vibration control, and structural optimization design for vibration reduction. Furthermore, the main results of existing research on the vibration control of fluid-conveying pipes are summarized, and future promising research directions are recommended to address the current research gaps. This paper contributes to the understanding of vibration control of fluid-conveying pipes, and will help the research work on the vibration control of fluid-conveying pipes attract more attention.

Vibration isolation systems with quasi-zero stiffness (QZS) performance have been widely studied because of their characteristics: high static stiffness and low dynamic stiffness. However, the effective displacement range of QZS is usually so small that strongly limits its application existing in real engineering. Thus, this study’ main innovation is to attempt to expand the effective displacement range of the QZS system via a semi-active control strategy. We first present a novel quasi-zero stiffness (QZS) vibration isolation system. The QZS characteristic is achieved by combining a mechanism with six oblique springs and a coil spring, which provide negative stiffness and positive stiffness, respectively. The effects of inclination angles of oblique springs on the negative stiffness of the system are first discussed via the static analysis method. The dynamic characteristics under simple harmonic excitation are then analyzed using the harmonic balance method, including the jumping phenomena and force–displacement transmissibility. To further enlarge the effective displacement range of QZS, a feedback displacement strategy is utilized to actively adjust the inclination angles of oblique springs and realize the alteration of the stiffness of the QZS system. Results obtained from theoretical analysis show that, in the aspect of low-frequency vibration isolation performance, different from linear systems, the proposed QZS system has obvious advantages, and the displacement range of quasi-zero stiffness property is significantly expanded from a single equilibrium point to a relatively lager range when the semi-active control strategy is implemented. Furthermore, the virtual prototype simulation results reveal that the proposed QZS system can maintain excellent vibration isolation performance under significant amplitude vibration after adding control.

To further improve the multi-objective comprehensive vibration isolation performance of commercial vehicles and save network resource occupation, this paper proposes a new configuration of semi-active quasi-zero stiffness air suspension (QZSAS) with network communication architecture, and a matching dynamic output feedback control (DOFC) strategy considering event-triggered mechanism. The semi-active QZSAS is mainly composed of a positive stiffness air spring, a pair of negative stiffness double-acting cylinders and two continuous damping controlled (CDC) dampers. Event-triggered mechanism determines whether the control signal is updated by judging the measured signal to save communication resources. Firstly, the nonlinear stiffness of the suspension system is regarded as an uncertain parameter and processed by constructing a Takagi–Sugeno (T-S) fuzzy controller model. Then, the Lyapunov–Krasovskii functional method is employed to design the dynamic output feedback controller under the linear matrix inequality constraint to ensure system stability with H ∞ performance index. Finally, the co-simulation and hardware-in-the-loop (HiL) test results show that the presented new semi-active QZSAS structure and the DOFC method considering event-triggered mechanism can significantly improve the multi-objective performance of commercial vehicles under different driving conditions with significantly reducing the network communication burden.

In this work, a semi-active quasi-zero-stiffness (QZS) vibration isolation system with controllable lateral springs was proposed and its practical vibration isolation effectiveness was demonstrated through theoretical and experimental studies. A semi-active control strategy was developed to allow for the regulation of the lateral spring length to address the large resonant responses in the low-frequency range of the QZS system, while maintaining QZS benefits of increasing the control bandwidth with sufficiently low transmissibility and satisfactory static stiffness. The effect of the length of the lateral springs on the negative stiffness of the system under static conditions was investigated, and the stability of the system was analyzed to ensure the system’s stability during its operation. Moreover, by employing the semi-active control strategy with the resonance-detuning approach, the dynamic characteristics of the QZS system could be altered from linear to nonlinear through the highly-responsive adjustment of the lateral spring stiffness. As a result, the excitation of low-frequency resonance could be avoided while simultaneously obtaining an increase of control bandwidth with low transmissibility. Specifically, experimental results showed that the developed QZS vibration isolation system could achieve a reduction of transmissibility peaks by 9.68 dB and 15.59 dB, compared to the linear isolation system and the QZS vibration isolation system without control, respectively. The QZS vibration isolation system also achieved an overall reduction in vibration transmissibility with its low-frequency 0-dB bandwidth reduced by 11.8% (from 3.64 to 3.21 Hz) when compared to the linear system, demonstrating an improved vibration isolation effectiveness.

In this paper, the instability of semi-active control systems caused by the utilization of semi-active inerters is analyzed. The purpose of this study is to demonstrate the possibility of inducing instability by applying semi-active inerters in vibration control systems, a phenomenon which is essential for the applications of semi-active inerters but has not been drawn much attention in the existing results. A constructive method is proposed to prove the instable effect caused by switching-state semi-active inerters based on a general multi-degree-of-freedom (DOF) mass-chain system. The underlying idea in the proof is to construct a multi-DOF unstable semi-active control system with semi-active inerters based on its 1-DOF counterparts. First of all, it is theoretically proved that for a 1-DOF system, both undamped and damped cases, instability can be induced by semi-active inerters under certain switching laws. Then, following the idea of modal analysis, unstable n -DOF semi-active inerter-based system with proportional damping is constructed via coordinate transformation. Moreover, for general damping case, phase portraits are depicted to show the instability caused by semi-active inerters. In this way, the conclusion is reached that semi-active inerter can induce instability if the inertance improperly controlled, and such a finding is still valid when the inerter nonlinearities are considered. Hence, the stability issue should not be neglected in the practical application of semi-active inerters.

•Model-free VRFT applied to ADRC combined with fuzzy control is proposed.•Least-squares algorithm specific to VRFT is replaced with Grey Wolf Optimizer.•The fuzzy control system stability is employed in the design approaches.•Model-free optimal tuning of controllers for tower crane systems is done.•Experimentally validated model-free controllers are offered. This paper proposes the Virtual Reference Feedback Tuning (VRFT) of a combination of two control algorithms, Active Disturbance Rejection Control (ADRC) as a representative data-driven (or model-free) control algorithm and fuzzy control, in order to exploit the advantages of data-driven control and fuzzy control. The combination of Active Disturbance Rejection Control with Proportional-Derivative Takagi-Sugeno Fuzzy Control (PDTSFC) tuned by Virtual Reference Feedback Tuning results in two novel data-driven algorithms referred to as hybrid data-driven fuzzy ADRC algorithms. The main benefit of this combination is the automatic optimal tuning in a model-free manner of the parameters of the combination of Active Disturbance Rejection Control with Proportional-Derivative Takagi-Sugeno Fuzzy Control called ADRC-PDTSFC. The second benefit is that the suggested combination is time saving in finding the optimal parameters of the controllers. However, since Virtual Reference Feedback Tuning generally works with linear controllers to solve a certain optimization problem and the fuzzy controllers are essentially nonlinear, this paper replaces the least-squares algorithm specific to Virtual Reference Feedback Tuning with a metaheuristic optimization algorithm, i.e. Grey Wolf Optimizer. The fuzzy control system stability is guaranteed by including a limit cycle-based stability analysis approach in Grey Wolf Optimizer algorithm to validate the next solution candidates. The hybrid data-driven fuzzy ADRC algorithms are validated as controllers in terms of real-time experiments conducted on three-degree-of-freedom tower crane system laboratory equipment. To determine the efficiency of the new hybrid data-driven fuzzy ADRC algorithms, their performance is compared experimentally with that of two control algorithms, namely Active Disturbance Rejection Control with Proportional-Derivative Takagi-Sugeno Fuzzy Control, whose parameters are optimally tuned by Grey Wolf Optimizer in a model-based manner using the nonlinear process model. [Display omitted]

This paper deals with the active vibration control of piezoelectric sandwich plate. The structure consists of a substrate plate layer sandwiched between two layers of piezoelectric sensor and actuator. Based on laminate theory and constitutive equation of piezoelectric material, the vibration active control dynamic equation of the sandwich structure is established by using hypothetical mode method and Hamilton principle. The Rayleigh-Ritz method is used to solve it. The form of hypothetical solution is used for approximate solution, which is simple and accurate. The method of this paper is verified by several examples. The parametric studies of the sandwich plate structures are carried out. The results show that applying different boundary conditions and piezoelectric patch positions to the structures have a great influence on the natural frequency. When the driving voltage increases, the deflection of the plate structures increase approximately linearly. The active vibration control studies are investigated as well. The results show that within a certain range, the larger the value of the speed feedback coefficient, the better the active control effect. The positions of the piezoelectric patches affect the effectiveness and cost of active control. When the piezoelectric plate is located at the fixed end, the effect and cost of active control are better than that at the midpoint and free end of the plate.

This paper investigates the high-performance attitude control and active vibration suppression problem for flexible spacecraft in the presence of external disturbances. The active vibration control usually depends on additional sensors and actuators, which will highly increase the difficulty of practical application. In order to reduce the implementation complexity, the piezoelectric sensors are not adopted, but instead a modal observer is introduced to estimate the modal information. Based on the observed modal information and the prescribed performance design process, an adaptive attitude controller is developed, which has the capabilities of rejecting disturbances as well as possessing predetermined transient and steady-state control performance. Similarly, an active controller is constructed to deal with the vibrations induced by attitude motions. It can be proved that by constraining the estimations of the modal variables, the actual modal coordinate will also be constrained with expected attenuation characteristics. The stability of the entire closed-loop system is analyzed by the Lyapunov theory. Simulation results in different cases show the effectiveness and performance of the proposed algorithms.