The application of infrared spectroscopy and DFT calculations to better understand interactions between bosentan hydrate and sildenafil base induced by high energy ball milling.

Terahertz fingerprints of BNA crystal: Anisotropic absorption of low-frequency modes and its impact on terahertz generation efficiency.

A longitudinal-flexural ultrasonic transducer with acoustic black hole disk for generating intense airborne acoustic radiation.

Vibration and acoustic response characteristics of re-entrant auxetic core quadrilateral sandwich panel with multi-phase composites facing under supersonic flow

Vibrational characteristics of porous functionally graded rectangular plates

Spectral-asymptotic homogenization solution for vibration characteristics of hourglass lattice sandwich panels

Vibration characteristics of a pre-twisted multi-blades-hub rotor system with blade stiffness mistuning

Abstract This study investigates the radial vibration behavior of an isotropic, elastic, hollow cylinder subjected to a uniform axial magnetic field. Using the principles of magneto-elasticity and classical elasticity theory, the governing equations are derived. Analytical solutions using Bessel functions are presented under stress-free boundary conditions. The impact of the magnetic field on the natural frequencies is discussed, demonstrating that the magnetic field significantly affects the vibrational characteristics of the structure. Keywords Radial vibration, hollow cylinder, magneto-elasticity, Bessel functions, magnetic field, natural frequencies

With the development of aerospace technology, hypersonic flight vehicles are evolving towards larger size, lighter weight, and higher performance. Their cross-domain maneuverability and extreme flight environment led to the rigid–flexible coupling effect and became the core bottleneck restricting performance improvement, seriously affecting flight stability and control accuracy. This paper systematically reviews the research status in the field of control for high-speed rigid–flexible coupling aircraft and conducts a review focusing on two core aspects: dynamic modeling and control strategies. In terms of modeling, the modeling framework based on the average shafting, the nondeformed aircraft fixed-coordinate system, and the transient coordinate system is summarized. In addition, the dedicated modeling methods for key issues, such as elastic mode coupling and liquid sloshing in the fuel tank, are also presented. The research progress and challenges of multi-physical field (thermal–structure–control, fluid–structure–control) coupling modeling are analyzed. In terms of control strategies, the development and application of linear control, nonlinear control (robust control, sliding mode variable structure control), and intelligent control (model predictive control, neural network control, prescribed performance control) are elaborated. Meanwhile, it is pointed out that the current research has limitations, such as insufficient characterization of multi-physical field coupling, neglect of the closed-loop coupling characteristics of elastic vibration, and lack of adaptability to special working conditions. Finally, the relevant research directions are prospected according to the priority of “near-term engineering requirements–long-term frontier exploration”, providing Refs. for the breakthrough of the rigid–flexible coupling control technology of the new-generation high-speed aircraft.

Pumps operated in turbine mode have attracted considerable attention for hydropower generation and water conveyance applications due to their economic advantage over conventional hydroturbines. Despite this benefit, their deployment remains constrained by limited flow controllability and pronounced instability when operating away from the design point. To address these challenges, the present work combines experimental measurements with numerical simulations to examine the unsteady flow behavior of an axial-flow pump under five distinct operating regimes, spanning deep part-load conditions at 5 L/min through the design point and into overload operation at 12.5 L/min. Pump stability was evaluated through detailed analyses of velocity distributions and pressure fluctuations in both the time and frequency domains. The results reveal a strong dependence of unsteady behavior on operating condition. At part-load operation, pressure pulsations intensify markedly, with peak-to-peak amplitudes increasing by as much as 15% relative to the design flow rate. Spectral analysis shows that rotor-stator interaction phenomena dominate the unsteady response, with the blade passing frequency and its harmonics contributing over 12% of the total spectral energy across most monitoring locations. As the flow rate approaches overload, the magnitude of pressure oscillations is reduced by approximately 14%, indicating a progressive improvement in hydraulic stability. The effect of impeller blade stagger was further investigated for three configurations, namely - 3°, 0°, and + 3°. Deviations from the baseline geometry (0°) significantly amplify flow unsteadiness, particularly in the rotor-stator interaction region. In these cases, pressure pulsation amplitudes increase by up to 16%, highlighting the sensitivity of unsteady flow structures to blade-angle modification. Overall, the findings demonstrate that both operating regime and impeller blade angle exert a decisive influence on the stability and dynamic performance of axial-flow pumps, offering valuable insights for their optimal design and operation under variable flow conditions.

Research on the transmission characteristics and spatial distribution characteristics of vibration in the cementing casing string system

High-performance polarization-sensitive photodetectors have attracted significant attention in optoelectronics. Low-dimensional semiconductors with asymmetric crystal lattices are ideal polarization detection media due to their inherent optical and electronic anisotropies. Among them, the emerging quasi-one-dimensional van der Waals metal phosphorus sulfide, Nb4P2S21, exhibits prominent in-plane optical anisotropy and broad UV-visible light absorption. To validate its application potential for polarization-sensitive photodetection, herein, the anisotropic lattice vibrational and optical characteristics of Nb4P2S21 were systemically investigated by angle-resolved polarized Raman, transmission, and reflection spectroscopies. Leveraging these properties, we fabricate a planar two-terminal Nb4P2S21-based photodetector, which demonstrates a stable broadband photoresponse and pronounced polarization sensitivity, delivering a responsivity of 0.29 mA W−1 and a high anisotropic ratio of 2.53 at 405 nm. Beyond revealing fundamental correlations between crystal symmetry and optical response, these findings establish Nb4P2S21 as a promising candidate for next-generation polarization-sensitive optoelectronic devices.

Abstract The thermal properties of ternary MgCu2O3 compound have been investigated using density functional theory (DFT) in conjunction with density functional perturbation theory (DFPT) and quasi-harmonic approximation (QHA). The phonon band structure and phonon density of states (PhDOS) are calculated to establish the lattice dynamical stability and vibrational characteristics of the compound. Based on the phonon spectra, the temperaturedependent thermodynamic quantities, including the thermal expansion coefficient, heat capacities at constant pressure and constant volume, entropy, and isothermal bulk modulus, are evaluated. The results provide comprehensive insight into the vibrational and thermodynamic behaviour of MgCu2O3, highlighting the crucial role of lattice dynamics in governing its thermal properties.

This study presents an innovative approach for unveiling the hidden relationships between natural frequency patterns and structural parameters in grid-form frames. By analyzing vibrational characteristics, we determine key features, namely the number of vertical beams, boundary conditions, and aspect ratios. Extensive finite element analysis generates a dataset, mapping the natural frequencies as features against structural parameters as labels reveals distinct, streamlined clusters in the feature hyperspace, highlighting an underlying order in the system’s dynamics. An advanced classification and interpolation model navigates these spectral trajectories to predict structural parameters accurately, even in the presence of damage or different materials. This study offers new insights into the intrinsic dynamics of complex structures, inviting further exploration into the subtle interplay between vibrational characteristics and structural identity. These findings open new avenues for research, potentially transforming the understanding of structural behavior in practical engineering applications.

As wind turbine blades continue to evolve toward longer and more flexible designs, they undergo significant nonlinear damping effects during fatigue testing. This damping inhibits the response amplitude of the blades, thereby placing higher demands on the performance of fatigue loading equipment. To assess fatigue testing loading schemes for large blades, this paper considers both linear and aerodynamic damping, establishes a nonlinear dynamic model of the blade testing system, and analyzes the amplitude-frequency characteristics under nonlinear damping. Based on the principle of functional equivalence, it further constructs mathematical relationships between the blade’s equivalent damping ratio, response amplitude, and exciting amplitude. The results show that the response characteristics under nonlinear damping are influenced by the equivalent damping ratio, response amplitude, and vibration frequency. Experiments on four large blades verify the nonlinear mapping relationship between response and exciting amplitude. The equivalent damping ratio exhibits segmented characteristics, showing a near-linear positive correlation with the blade response at large amplitudes and remaining almost unchanged at small amplitudes. This paper provides a theoretical basis for selecting fatigue loading equipment and designing testing schemes. Additionally, the work offers significant experimental cases and theoretical support for further refining full-scale blade fatigue testing theories.

Space structures are a common element in modern architecture because of their expressive form and intrinsic geometric complexity, which allow architects to produce designs that are both aesthetically pleasing and structurally sound. The majority of studies and research on space structures have traditionally concentrated on their structural behaviour, highlighting elements like geometric stability, load distribution, and material efficiency. However, it is becoming more and more crucial to look at space structures from both an engineering and an architectural design standpoint as they continue to acquire traction in architectural practice. In the present study. Researches on dynamic analysis of space structures were widely carried out across the world. The study on structural behavior of grid, domes, vaults which are subjected to earthquake were carried out through many analytical and experimental works. The present work focuses on the study of orientation of stiffness of the supporting roof, and the effect of peripheral cross-bracings on overall lateral response. Further, dynamic analysis has been carried out for grid space structure with different horizontal bracings. Finally, criticality and its locations in various configurations of the space structures are identified. Based on the results and discussions, it is concluded that, the presence of horizontal and vertical bracings will resist the lateral load efficiently and particularly in model 5 where cross bracings are provided. From linear time history analysis, it can be concluded that, the presence of fixed base, vertical bracings and horizontal bracings has significant effect on the vibration characteristics. Presence of horizontal and vertical bracings will contribute significantly in resisting the lateral load of grid space structures.

ABSTRACT Structural health monitoring (SHM) systems often face challenges due to missing or incomplete vibration signals caused by sensor failures, transmission disruptions, or environmental disturbances. To address these issues, we propose WaveNet_GRU, a novel deep learning (DL) model that integrates three key components: dilated causal convolutions for capturing multiscale temporal patterns, gated activation units to enhance nonlinearity and feature selection, and gated recurrent units (GRU) to model long‐term temporal dependencies in structural dynamics. This unified architecture enables WaveNet_GRU to efficiently capture both local fluctuations and global temporal trends in vibration signals. We evaluate the model using two benchmark datasets: a laboratory‐scale physical model of a cable‐stayed bridge and the real‐world Rach Mieu 1 Bridge in Vietnam, under varying missing data rates (10%–30%). Experimental results demonstrate that WaveNet_GRU consistently outperforms baseline models, including standalone GRU and WaveNet‐based architectures. In particular, on the real‐world Rach Mieu 1 Bridge dataset, WaveNet_GRU achieved the highest accuracy with a Coefficient of Determination ( R 2 ) exceeding 0.91 and the lowest Root Mean Square Error (RMSE) under 10% missing data conditions. Furthermore, the model demonstrated superior robustness by maintaining reliable performance even when data loss reached 30%, whereas baseline models exhibited significant degradation. By preserving subtle vibration features during reconstruction, WaveNet_GRU helps maintain continuous monitoring, supporting earlier damage indication and more cost‐effective maintenance planning in practical SHM.

To address severe equipment vibration and large load fluctuations during hard-rock excavation, this study proposes mechanical pre-cracking as a preparatory treatment. A hard-rock model containing pre-cracked holes is developed using the discrete element method; the crack initiation and propagation induced by a hydraulic cracker are simulated. The rock models before and after pre-cracking and a rigid-flexible coupling model of the roadheader are then analysed jointly via DEM-MFBD two-way coupling, and the cutting loads and vibration responses are systematically examined. Results indicate that the three-way average load on the cutting head is reduced by 8.2% and the load fluctuation coefficient decreases from 0.0242 to 0.0213 following rock pre-cracking, effectively mitigating impact loads. Frequency-domain analysis shows that, within the principal vibration band of 20-30Hz, the vibration-acceleration amplitudes of the cutting head, cutting arm and slewing table are reduced by 14.7%, 8.7% and 3.6%, respectively, demonstrating a "near-loaded component" vibration response. This reveals an attenuation law along the transmission path: components closer to the load exhibit superior vibration damping compared with remote elements. The study confirms that mechanical pre-cracking achieves effective vibration attenuation at the source by reducing the overall stiffness of the rock mass and altering the rock-breaking pattern, thereby providing a theoretical basis and engineering reference for improving the efficiency and reliability of hard-rock tunnelling equipment.

This study investigates the vibrations at the Castello Svevo-Normanno in Aci Castello (Catania), focusing on its historical and cultural significance. The research aims to analyze vibration levels and frequency distribution to achieve two objectives: protecting historical artifacts and structures through preventive vibration analysis and exploring the use of kinetic energy for powering autonomous systems. The study specifically focuses on the indoor context to understand its unique vibrational characteristics. Measurements were recorded along the X, Y, and Z axes, with detailed analysis of the Z axis using Fast Fourier Transform (FFT) and Power Spectral Density (PSD). The results revealed consistent vibration patterns across all axes, with the Z axis significantly influenced by environmental factors such as wind and sea movement. These findings provide valuable insights for designing optimized energy harvesting systems, electromechanical converters, and monitoring devices suitable for operation in this specific historical context.

Abstract An investigation is conducted to ascertain the feasibility of using integrated probabilistic design to evaluate structural integrity of composite fan blade used in advanced high-bypass-ratio turbofan engines. The structural probability analysis obtains statistical properties at the macroscopic level under multiscale uncertainties and quantifies the failure probabilities of design criteria against static damage initiation and resonance margins. Due to the geometry and laminate design complexity, this represents an extremely intricate but novel application for forward uncertainty quantification. Nonintrusive polynomial chaos expansion (PCE), Gaussian process, and field metamodel are established and validated. A suitable compromise among affordable computation cost and prediction accuracy is fulfilled. For field quantities, uncertainty of ply stresses and modal displacement are evaluated through field statistical measures. Variance-weighted average of the explained variance is evaluated for ply stress by synthetic random field discretization. It shows that fiber orientation explains 81.1% variance of ply stress field and covers a great layer extent, whereas ply thickness is rather small and has a slight influence on field variance. Ply stress field is a non-Gaussian and nonstationary random process. At last, static damage and resonance frequency design are fully illustrated in probabilistic manner. Failure probability of static damage is 1.48 × 10−4, and the second bending mode has the maximum resonance probability, which could help the engineer understand the potential risks of structural design for composite fan blades.