Search Results (781)

With the high proportion of wind and photovoltaic (PV) power connection in the new electricity system, the system output power volatility is enhanced. When the output fluctuation of the system is suppressed, the pumped storage condition is changed frequently, which leads to the vibration enhancement of the unit and a decrease in the system safety. This paper proposes a pump turbine health evaluation model based on the combination of a weighting method and cloud model in a high proportion wind and PV power connection scenario. The wind–PV output characteristics of the complementary system in a year (8760 h) and a typical week in four seasons (168 h) are analyzed, and the characteristics of frequent working condition transitions of pumped storage units are studied against this background. A five-level health classification system including multi-dimensional evaluation indicators is established, and a multi-level health evaluation based on cloud membership quantification is realized by combining the weighting method and cloud model method. The case analysis of a pumped storage power station within a new electricity system shows that the system as a whole presents typical cloud characteristics (Ex = 76.411, En = 12.071, He = 4.014), and the membership degree in the “good” state reaches 0.772. However, the draft tube index (Ex = 62.476) and the water guide index (Ex = 50.333) have shown a deterioration trend. The results verify the applicability and reliability of the evaluation model. This study provides strong support for the safe and stable operation of pumped storage units in the context of the high-proportion wind and PV power connection, which is of great significance for the smooth operation of the new electricity system. Full article

In this paper, a generalized acoustic black hole (ABH) beam covered with a viscoelastic layer is proposed to improve the energy dissipation based on the double-parameter Mittag–Leffler (ML) function. Since fractional-order constitutive models can more accurately capture the properties of viscoelastic materials, a fractional dynamic model of an ABH structure covered with viscoelastic film is established based on the fractional Kelvin–Voigt constitutive equation and the mechanical analysis of composite structures. To analyze the energy dissipation of the viscoelastic ML-ABH structures under steady-state conditions, the wave method is introduced, and the theory of vibration wave transmission in such non-uniform structures is extended. The effects of the fractional order, the film thickness and length, and shape function parameters on the dynamic characteristics of the ABH structure are systematically investigated. The study reveals that these parameters have a significant impact on the vibration characteristics of the ABH structure. To obtain the best parameters of the shape function under various parameters, the Particle Swarm Optimization (PSO) algorithm is employed. The results demonstrate that by selecting appropriate ML parameters and viscoelastic materials, the dissipation characteristics of the structure can be significantly improved. This research provides a theoretical foundation for structural vibration reduction in ABH structures. Full article

The excessive vibration or collapse of a transmission tower-line (TTL) system under seismic excitation can result in significant losses. Viscoelastic material dampers (VMDs) have been recognized as an effective method for structural vibration mitigation. Most existing studies have focused solely on the dynamic analysis of TTL systems with control devices under deterministic seismic excitations. Studies focusing on the nonstationary stochastic control of TTL systems with VMDs have not been reported. To this end, this study proposes a comprehensive analytical framework for the nonstationary stochastic responses of TTL systems with VMDs under stochastic seismic excitations. The analytical model of the TTL system is formulated using the Lagrange equation. The six-parameter model of VMDs and the vibration control method are established. Following this, the pseudo-excitation method (PEM) is applied to compute the stochastic response of the controlled TTL system under nonstationary seismic excitations, and a probabilistic framework for analyzing extreme value responses is developed. A real TTL system in China is selected to verify the validity of the proposed method. The accuracy of the proposed framework is validated based on the Monte Carlo method (MCM). A detailed parametric investigation is conducted to determine the optimal damper installation scheme and examine the effects of the service temperature and site type on stochastic seismic responses. The nonstationary stochastic seismic responses of the TTL system are consistent with those based on MCM, validating the accuracy of the proposed analytical framework. VMDs can effectively suppress the structural dynamic responses, with particularly stable control over displacement. The temperature and site type have a notable influence on the stochastic seismic responses of the TTL system. The research findings provide important references for improving the seismic performance of VMDs in TTL systems. Full article

The vector control method is applied to a whole angle hemispherical resonator gyroscope (HRG). The detection and control of the resonator vibration state are implemented using orthogonal X/Y channels. However, the performance of the HRG is limited by the asymmetry in the gain and phase delay of X/Y channels. To address these issues, a novel detection circuit is proposed. The circuit leverages the closed-loop characteristics to achieve symmetry and stability in the X/Y channel gain while simultaneously eliminating phase delays within the loop. Firstly, a closed-loop single-channel time division multiplexing circuit is designed to overcome the deficiencies of the traditional dual-channel circuit. Secondly, a model is developed to analyze the time division detection errors, and an improved demodulation method is proposed to mitigate detection errors. Lastly, experimental results demonstrate that the designed circuit successfully suppresses drift in both gain and phase delay within the loop, confirming the effectiveness of the proposed solution in enhancing the performance of the HRG. Full article

In general, the joints of collaborative robots are equipped with reducers that exhibit inherent elasticity rather than pure rigidness. Consequently, for joint control in robotic systems, the speed fluctuation observed on the motor side does not fully represent the speed fluctuation on the reducer side. The speed fluctuations are strongly correlated with joint vibrations, particularly in a six-axis collaborative robot structure, where the second axis experiences the most significant load variation and poses the greatest control challenges. To address this issue while considering cost-effectiveness, one potential solution is to install an additional encoder solely on the second axis of the collaborative robot, which could enhance the overall performance of the system. Alternatively, adding an encoder to each axis of the reducer would yield superior results, albeit at a higher cost. This paper proposes a vibration suppression strategy based on dual encoders, where one encoder is installed on the motor side and the other on the reducer side. The ratio of the measured speeds from these two encoders corresponds to the reduction ratio of the reducer. By integrating the data from both encoders into the servo control, the vibration of collaborative robots can be effectively mitigated. This paper analyzes the transfer function of the entire system. Experimental results demonstrate that, compared to joints equipped with only a single encoder on the motor side, the dual-encoder configuration significantly reduces speed fluctuation on the reducer side under various operating conditions. These findings validate the correctness and feasibility of the proposed dual-encoder vibration suppression strategy. Full article

Distributed Acoustic Sensing (DAS) has emerged as a groundbreaking technology in seismology, transforming fiber-optic cables into dense, cost-effective seismic monitoring arrays. DAS makes use of Rayleigh backscattering to detect and measure dynamic strain and vibrations over extended distances. It can operate using both pre-existing telecommunication networks and specially designed fibers. This review explores the principles of DAS, including Coherent Optical Time Domain Reflectometry (COTDR) and Phase-Sensitive OTDR (ϕ-OTDR), and discusses the role of optoelectronic interrogators in data acquisition. It examines recent advancements in fiber design, such as helically wound and engineered fibers, which improve DAS sensitivity, spatial resolution, and the signal-to-noise ratio (SNR). Additionally, innovations in deployment techniques include cemented borehole cables, flexible liners, and weighted surface coupling to further enhance mechanical coupling and data accuracy. This review also demonstrated the applications of DAS across earthquake detection, microseismic monitoring, reservoir characterization and monitoring, carbon storage sites, geothermal reservoirs, marine environments, and urban infrastructure surveillance. The study highlighted several challenges of DAS, including directional sensitivity limitations, vast data volumes, and calibration inconsistencies. It also addressed solutions to these problems, such as advances in signal processing, noise suppression techniques, and machine learning integration, which have improved real-time analysis and data interpretability, enabling DAS to compete with traditional seismic networks. Additionally, modeling approaches such as full waveform inversion and forward simulations provide valuable insights into subsurface dynamics and fracture monitoring. This review highlights DAS’s potential to revolutionize seismic monitoring through its scalability, cost-efficiency, and adaptability to diverse applications while identifying future research directions to address its limitations and expand its capabilities. Full article

To address the vehicle-bridge coupling vibration issue of the Qingyuan Maglev Tourist Line, it is necessary to establish a maglev vehicle–bridge coupling dynamics simulation model that reflects the actual line conditions. Based on the vehicle and bridge structural parameters of the Qingyuan Maglev Tourist Line, this paper utilizes multi-body dynamics simulation software to create a medium–low-speed maglev vehicle dynamics model, and employs finite element software to construct a bridge model. Using the modal reduction method, the bridge finite element model is imported into the vehicle dynamics model through a rigid–flex coupling interface, establishing a medium–low-speed maglev vehicle suspension system–bridge coupling dynamics model. The accuracy of the established coupling simulation model was verified by comparing the simulation data from the coupling model with the dynamic response measured data from the Qingyuan Maglev Tourist Line. Finally, the impact of different control parameters on the vehicle–bridge coupling system was calculated, and the results indicate that selecting appropriate suspension control parameters can reduce the coupling vibration response between the maglev vehicle and the bridge. The main work of this paper is closely related to engineering, modeling based on the actual maglev line’s vehicle and bridge parameters, and validating the model through the dynamic test results of the line, laying the foundation for the suppression of maglev vehicle–bridge coupling vibration and system optimization. Full article

Rolling bearing vibration signals in rotating machinery exhibit complex nonlinear and multi-scale features with redundant information interference. To address these challenges, this paper presents a multi-scale channel mixing convolutional network (MSCMN) and an enhanced deep residual shrinkage network (eDRSN) for improved feature learning and fault diagnosis accuracy in industrial settings. The MSCMN, applied in the initial and intermediate network layers, extracts multi-scale features from vibration signals, providing detailed information. By incorporating 1 × 1 convolutional blocks, the MSCMN mixes and reduces the feature dimensions, generating attention weights to suppress the interference from redundant information. Due to the high noise and nonlinear nature of industrial vibration signals, traditional linear layer representation is often inadequate. Thus, we propose an eDRSN with a Kolmogorov–Arnold Network–linear layer (KANLinear), which combines linear transformations with B-spline interpolation to capture both linear and nonlinear features, thereby enhancing threshold learning. Experiments on datasets from Case Western Reserve University and our laboratory validated the efficacy of the MSCMN-eDRSN model, which demonstrated improved diagnostic accuracy and robustness under noisy, real-world conditions. Full article

Despite notable advancements in the development of borate materials, improving their luminescent efficiency remains an important focus in materials research. The synthesis of lanthanum borates (LaBO₃), doped and co-doped with europium (Eu³⁺) and dysprosium (Dy³⁺), by the solid-state method, has demonstrated significant potential to address this challenge due to their unique optical properties. These materials facilitate efficient energy transfer from UV-excited host crystals to trivalent rare-earth activators, resulting in stable and high-intensity luminescence. To better understand their structural and vibrational characteristics, Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy were employed to identify functional groups and molecular vibrations in the synthesized materials. Additionally, X-ray diffraction (XRD) analysis was conducted to determine the crystalline structure and phase composition of the samples. All observed transitions of Eu³⁺ and Dy³⁺ in the excitation and emission spectra were systematically analyzed and identified, providing a comprehensive understanding of their behavior. Although smartphone cameras exhibit non-uniform spectral responses, their integration into this study highlights distinct advantages, including contactless interrogation, effective UV excitation suppression, and real-time spectral analysis. These capabilities enable practical and portable fluorescence sensing solutions for applications in healthcare, environmental monitoring, and food safety. By combining advanced photonic materials with accessible smartphone technology, this work demonstrates a novel approach for developing low-cost, scalable, and innovative sensing platforms that address modern technological demands. Full article

This study investigated the thermophysical properties of TWIP steel with respect to grain size. The coefficient of thermal expansion (β) of TWIP steel was approximately 22.4 × 10⁻⁶ °C⁻¹, and this value was hardly affected by the grain size. Therefore the density of TWIP steel was also unaffected by grain size within the tested range. The β in TWIP steel was higher than that of plain carbon steels (13–15 × 10⁻⁶ °C⁻¹) such as interstitial free (IF) steel and low-carbon steel, and stainless steels (18–21 × 10⁻⁶ °C⁻¹) such as X10NiCrMoTiB1515 steel and 18Cr-9Ni-2.95Cu-0.58Nb-0.1C steel. The specific heat capacity (c_p) increased with temperature because the major factor affecting c_p is the lattice vibrations. As the temperature increases, atomic vibrations become more active, allowing the material to store more thermal energy. Meanwhile, c_p slightly increased with increasing grain size since grain boundaries can suppress lattice vibrations and reduce the material’s ability to store thermal energy. The thermal conductivity (k) in TWIP steel gradually increased with temperature, consistent with the behavior observed in other high-alloy metals. k slightly increased with grain size, especially at lower temperatures, due to the increased grain boundary scattering of free electrons and phonons. This trend aligns with the Kapitza resistance model. While TWIP steel with refined grains exhibited higher yield and tensile strengths, this came with a decrease in total elongation and k. Thus, optimizing grain size to enhance both mechanical and thermal properties presents a challenge. The k in TWIP steel was substantially lower compared with that of plain carbon steels such as AISI 4340 steel, especially at low temperatures, due to its higher alloy content. At room temperature, the k of TWIP steels and plain carbon steels were approximately 13 W/m°C and 45 W/m°C, respectively. However, in higher temperature ranges where face centered cubic structures are predominant, the difference in k of the two steels became less pronounced. At 800 °C, for example, TWIP and plain carbon steels exhibited k values of approximately 24 W/m°C and 29 W/m°C, respectively. Full article

In order to mitigate the vibration caused by fluid–structure interaction in water-conveying pipelines, a semi-active control method based on a magnetorheological (MR) damper is proposed. First, the partial differential equation governing the pipeline micro-element, which is simply supported at both ends, is formulated. This equation is then transformed into state-space expressions through non-dimensionalization and the Galerkin method. Based on passive dissipative control theory, a semi-active control law ensuring Lyapunov global asymptotic stability is derived based on the relative motion between the dynamic vibration-absorbing mass and the pipeline. Next, an on–off control algorithm is designed for the MR damper. The results of simulation and hardware-in-loop experiments demonstrate that the semi-active control law can significantly reduce the vibration of the pipeline system. The contribution of this research is to propose a new MR tuned mass damper (MR-TMD) to suppress vibration in water-conveying pipelines. The proposed MR-TMD scheme and its control method provide a theoretical basis and practical reference for the engineering application of semi-active vibration control in water-conveying pipelines. Full article

As components in direct contact with drivers and passengers in complex and challenging road conditions, automotive seats need to effectively absorb and isolate vibrations from the automotive chassis to minimize any adverse effects on the human body. In response to the issue of inadequate vibration isolation within multiple frequency bands for car seats, which can lead to discomfort for passengers, a vibration-damping seat structure equipped with an eddy current damper using electromagnets as the magnetic field source is proposed, and its vibration suppression characteristics are studied. First, a semi-active suspension damping structure is designed based on an eddy current damping effect. Second, the theoretical model of the semi-active suspension damping structure based on an eddy current effect is established, and the characteristic parameters of adjustable damping and their relationship with the amplitude response are analyzed. Finally, electromagnetic simulation analysis is conducted, and the results are compared with the theoretical model analysis results to verify the analysis, and the vibration suppression law of the semi-active suspension damping structure based on an eddy current effect is explored. Full article

Industrial parts are increasingly being designed to be more lightweight in modern manufacturing for energy saving and material cost reduction. However, the high-speed motion of flexible systems tends to excite severe residual vibrations that result in positioning accuracy degradation and loss of productivity. This study proposes a closed-form trajectory optimization method for vibration suppression based on trapezoidal velocity profiles, which are most widely used in industrial robots and machines. First, the formulation and minimum time solution under actuator limits of the motion profile are defined. Then, the relationship between the trajectory parameters and the vibration response is investigated. It is shown that residual vibration can be eliminated by properly tuning the acceleration/deceleration switching times according to the natural frequency. Based on the derived vibration suppression conditions, a tuning procedure for time parameters compliant with actuator limits is established to generate fast and precise movement. A main advantage of the proposed method is easy implementation for general machines without requiring extra computational resources or modification to the control system. The effectiveness and practicality of the proposed approach are verified through experiments conducted on a robot. The experimental results show that the optimized trajectory achieves superior residual vibration reduction performance. Full article

In order to break the bottleneck of the integer-order transfer function in vehicle ISD (inerter-spring-damper) suspension design, a positive real synthesis design method of vehicle mechatronic ISD suspension based on the fractional-order biquadratic transfer function is proposed. The emergence of the fractional-order components disrupts the equivalence relationship between the passivity of components and the positive realness of integer-order transfer functions in traditional networks. In this paper, the positive real condition of the fractional-order biquadratic transfer function is given. Then, a quarter dynamic model of the vehicle mechatronic ISD suspension is established, and the parameters of the fractional-order biquadratic transfer function and vehicle suspension are obtained by an NSGA-II multi-objective genetic algorithm. Moreover, the structure of the external circuit and the parameters of the electrical components are obtained by the fractional-order passive network synthesis theory. The simulation results show that under the condition of random road input and vehicle speed of 20 m/s, the root-mean-square (RMS) value of the vehicle body acceleration and the dynamic tire load of the fractional-order ISD suspension are reduced by 7.98% and 18.75% compared with the traditional passive suspension, while under the same condition, the integer-order ISD suspension can only reduce by 5.34% and 16.07%, respectively. The results show that employing a fractional-order biquadratic electrical network in the vehicle mechatronic ISD suspension enhances vibration isolation performance compared with the suspension using an integer-order biquadratic electrical network. Full article

This study aimed to investigate the structure-borne sound suppression of a strongly/weakly excited curved panel. Quadratic nonlinear resonance can induce anti-symmetric modal responses to replace symmetric modal responses, even though the physical panel dimensions and excitation distribution are symmetric. Unlike cubic nonlinear resonance, quadratic nonlinear resonance can be induced regardless of whether the panel vibration amplitude is small or large. As the sound radiation efficiency of anti-symmetric responses is much lower than that of symmetric responses, this quadratic nonlinear resonance effect is thus used for sound suppression. A set of multimode formulations was developed from the nonlinear structural governing equation and sound radiation efficiency equation. The quadratic nonlinear resonant responses and some other nonlinear responses were computed from the multimode formulations. Modal convergence studies and parametric studies were performed to understand the effects of various parameters on the quadratic nonlinear responses and sound suppression. The results showed that when the panel was strongly excited, the difference between the peak sound levels in the linear and nonlinear cases was up to 12 dB, and when the panel was weakly excited, the difference was up to 6 dB. Full article