关键词： cable force identification   correction formula   dimensionless System   string theory  

摘要： Effective identification of cable forces with the string theory method is erucial for the assessment of cables. Here, to solve the application problem of cable' s string theory in engineering, the cable System dynamic equation was non-dimensionalized making the only parameter determining the System be the nominal slenderness ratio. The dimensionless nominal slenderness ratio-frequency curve was plotted, and based on the frequency differences between string theory and rigid cable theory, the applicable ränge of the string theory cable force calculation formula to meet specific cable force error requirements was given. For parts beyond applicable limits, taking the upper limit of frequency error as an example, the three-parameter frequency correction formula and the cable force correction formula were derived with the power function. Then, a cable force identification algorithm in the dimensionless System was proposed. The feasibility of the cable force correction formula was verified through examples from the literature, and it was applied in the field cable tests. It was shown that all cable force identification errors meet engineering requirements. The results demonstrated that frequency error curves with different accuracies can meet specific engineering applications of string theory, and provide theoretical support for solving practical engineering problems;the cable force correction formula is concise, intuitive, and unified in form with theoretical error within 2% covering the applicable ränge of nominal slenderness ratio of cables in engineering. © 2025 Chinese Vibration Engineering Society. All rights reserved.

关键词： Shrinkage  

摘要： Fast iterative shrinkage threshold algorithm (FISTA) based on fast Fourier transform (FFT-FISTA) has higher computational efficiency, but it ignores spatial Variation and winding error of point spread function to cause loss of sound source recognition Performance. Here, an improved FFT-FISTA algorithm based on function beamforming was proposed. This improved algorithm could take Output of function beamforming as iterative input of FFT-FISTA to establish a linear equation System for function beamforming, sound source distribution and rising power spatial transfer invariant point spread function. The linear equation System was iteratively solved based on FFT under periodic boundary conditions to make a calculated non-periodic function become a periodic function, solve the problem of wave number leakage brought by zero-filling boundary, improve the accuracy of Operation and further enhance imaging Performance. The main lobe of point spread function was sharpened through exponential Operation, and the applicability of the assumption of spatial transfer invariance of point spread function was expanded. Simulation and test results showed that compared with the conventional FFT-FISTA, the improved FFT-FISTA can improve imaging spatial resolution and dynamic ränge, expand the effective imaging area of FFT-FISTA;the compressed gas leakage experiment results verify the effectiveness of the improved FFT-FISTA. © 2025 Chinese Vibration Engineering Society. All rights reserved.

关键词： electro-hydraulic energy-regenerative Suspension (EHERS)   improved whale algorithm   LQR Controller   parametric adaptation  

摘要： Electro-hydraulic energy-regenerative Suspension (EHERS) has functions of damping adjustment and energy recovery, balancing Vibration reduction and energy consumption. A reasonable control System design can effectively improve the smoothness and energy consumption level of vehicles. Here, a LQR control strategy considering parametric adaption was proposed for EHERS to realize fast convergence and Performance optimization of EHERS control System. Firstly, due to high dependence of traditional LQR Controllers on experience in parametric selection, the improved whale algorithm was used to realize adaptive optimization of weighting coefficients, and effectively improve computational efficiency of control System. Secondly, changing linear convergence factor to a nonlinear one in traditional whale algorithm could realize a balance between global optimization and local optimization to effectively reduce optimization time. In addition, to solve the problem of existing algorithms easily falling into local Optimum, a strategy combining adaptive weighting coefficients and random difference variants was proposed to replace the individual update strategy in whale algorithm. Finally, a Simulation model for EHER-damper was established based on the Software AMESim, and an experimental platform was built to conduct experiments for damping characteristics. The Simulation results were consistent with experimental data to verify the correctness of EHER-damper model. Then, 3 types of Controllers of LQR, traditional whale algorithm optimized LQR and improved whale algorithm optimized LQR were built based on MATLAB/Simulink. A Joint Simulation model based on MATLAB/AMEsim was constructed for contrastive analyses with 3 types of Controllers on random road surfaces. Simulation results showed that the LQR Controller optimized based on the improved whale algorithm can reduce RMS values of vehicle acceleration and Suspension dynamic displacement by 38. 17% and 74. 71%, respectively, and increa

关键词： Offshore wind turbines  

摘要： Here, taking a6.45 MW offshore wind turbine support struoture as a prototype, and a scaled model with a similarity ratio of 1: 15 was designed for shaking table tests. A tuned liquid damper (TLD) was set at top of the model tower, multiple external excitations with different speetral characteristics were input to analyze and evaluate Vibration responses of offshore wind power structure and Vibration reduction Performance of TLD. The results showed that acceleration response of wind turbine tower structure is greatly affected by external excitation spectra, while its displacement response is mainly controlled by tower first-order fundamental frequency;due to tower top concentrated mass being eccentrically set, under bi-directional seismic inputting, tower has spatial torsion and a " beat Vibration" phenomenon appears at tower top;seismic excitation with rieh low-frequency components has a larger impact on structural Vibration than seismic excitation developed with high-frequency components does;after adding a TLD to tower top, the maximum acceleration response Vibration reduction rate can reach 30. 74%, the maximum displacement response Vibration reduction rate can reach 34. 48%, and the maximum stress Vibration reduction rate can reach 31. 94%;due to short duration and strong suddenness of earthquake excitation, TLD shaking has a time-delay to cause a poorer Vibration reduction effect on peak Vibration responses compared to harmonic excitation;however, time-domain response amplitudes of tower vibrations after Vibration reduction are significantly reduced, and their attenuation rates are accelerated;for frequency domain responses, spectral peaks disappear at resonance frequencies. © 2025 Chinese Vibration Engineering Society. All rights reserved.