Number Of Periods Research Articles

A generic detailed multibody model for simulating thoracic spine and ribcage kinematics

AbstractA reliable and comprehensive multibody musculoskeletal model of the thoracic spine and ribcage can offer valuable insight into the biomechanics of healthy and curved spines. In this study, we developed a generic rigid-body thoracic spine and ribcage model, which is kinematically determinate and controlled by spinal posture. A newly devised averaging constraint was implemented to model the kinematics of individual ribs and the sternum. Rib motion validation confirmed that the movement of adjacent ribs matched measured data across different tasks. We simulated 39 adolescent idiopathic scoliosis subjects aged 7–17 years, with an average (SD) Cobb angle of 15.9 (8.2) degrees. The average errors of multiple scoliosis metrics were less than 4 degrees for angle parameters, 5 mm for displacement parameters, and 3 percent for the ratio parameter. The model is straightforward and can simulate various daily activities (e.g., spinal articulation and breathing) while accurately capturing pathological deformities conforming to experimental data. It is available to the public on the open science platform Zenodo and will also be accessible through the AnyBody Managed Model Repository.

Use of a Refined Theory for Three-Dimensional Bending Analysis of Isotropic Rectangular Thick Plates

In this paper, a refined plate theory (Alternative II theory) is presented for the three-dimensional bending analysis of an Isotropic thick plate. The theory has similarity to the first order shear deformation theory but requires no shear correction factors. The kinematics equations were developed based on the Alternative II Refined plate theory. Thereafter, using a complete three-dimensional constitutive relation, the total potential energy was developed. A governing equation and two compatibility equations were obtained by the variation of the total potential energy with respect to displacement and rotations respectively. Solving the governing and compatibility equations, a polynomial displacement function was obtained. The stiffness coefficients were then obtained using the displacement function. Thereafter, the equations for the in-plane normal and shear stresses, transverse normal and shear stresses as well as the lateral displacement were developed using the stiffness coefficients and the displacement function. Numerical values of the lateral displacement parameters were determined for a rectangular plate of aspect ratio 2.0, 1.0 and 0.5 for span to thickness ratios of 20, 10 and 7.14286. Also, numerical values of the lateral displacement and stresses were determined for a square plate for span to thickness ratios of 4, 10, 100 and 1000. The results from this work were compared with the work of previous researchers using simple percentage difference. It was observed that refined plate theories overestimate the lateral displacement of a plate. Hence, three-dimensional analysis is recommended for thick plate analysis.

Phase Prediction via Crystal Structure Similarity in the Periodic Number Representation.

The periodic number (PN) representation of the chemical systems, introduced by Dmitri Mendeleev, uncovers the fundamental principle of chemical similarity in a straightforward way. In this framework, the rows correspond to the principal quantum numbers of the elements' electronic configurations when considered isolated atoms. This systematic arrangement allows for a deeper understanding of the relationships and patterns among the elements. In this study, we propose a novel strategy for structure type (prototype) prediction by utilizing the PN concept to identify possible modifications and phase stability of unexplored chemical systems. Our PN-based crystal structure prediction (PNcsp) program, which evaluates similarity through PN neighboring in the phase map, provides the most probable prototypes for unknown and unreported modifications of given phases in binary and higher order chemical systems. We applied PNcsp to 59 distinct chemical systems whose equimolar phases are indicated in the respective phase diagrams but lack accurate experimental structure determination. Our methodology identified 93 prototypes for these 59 equiatomic phases, of which 47 exhibit mechanical and dynamic stability. Notably, this approach discovered 19 entirely novel, fully stable polymorphic phases, thereby expanding the known landscape of potential materials. Furthermore, we demonstrated that this method is also effective for nonequimolar and higher order systems.

Assessing Static Balance, Balance Confidence, and Fall Rate in Patients with Heart Failure and Preserved Ejection Fraction: A Comprehensive Analysis.

Chronic heart failure (CHF) is a complex clinical syndrome, associated with frailty, higher fall rates, and frequent hospitalizations. Heart Failure (HF) and preserved ejection fraction (HFpEF) is defined as a condition where a patient with HF have a diagnosis of left ventricular ejection fraction (LVEF) of ≥ 50%. The risk of HFpEF increases with age and is related to higher non-cardiovascular mortality. The aim of this study was to evaluate static balance and examine the effect of task difficulty on the discriminating power of balance control between patients with HFpEF (Patients with HFpEF) and their healthy controls. Moreover, the associations between static balance parameters, balance confidence, falls, lean muscle mass, and strength were assessed. Seventy two patients with HFpEF (mean age: 66.0 ± 11.6 years) and seventy two age- and gender-matched healthy individuals (mean age: 65.3 ± 9.5 years) participated in this study. Participants underwent a 30 s bilateral stance (BS) test and a 20 s Tandem-Romberg stance (TRS) on a force platform, evaluating the Range and Standard Deviation of Center of Pressure (COP) displacement parameters in both axes. Balance confidence was evaluated by the Activities-Specific Balance Confidence (ABC) Scale, and the number of falls during the last year was recorded. Lower limb strength was measured using an isokinetic dynamometer, isometric leg strength, and a Sit-to-Stand test. Bioelectrical impedance analysis was conducted to assess lean fat mass, lean fat mass index, and lean%. Patients with HFpEF presented with lower static balance in BS and TRS compared to healthy controls (p < 0.05), lower balance confidence by 21.5% (p < 0.05), and a higher incidence of falls by 72.9% (p < 0.05). BS was a better descriptor of the between-group difference. Furthermore, static balance, assessed in controlled lab conditions, was found to have little if no relationship to falls, strength, lean muscle mass, and balance confidence. Although no correlation was noted between the static balance parameters and falls, the fall rate was related to balance confidence, age, muscle strength, and lean fat.

Investigation into forces on offshore piles with constant and linearly varying diameters using CFD and extended Morison equation under separate wave and current loadings

This study presents a comparative analysis of hydrodynamic forces on cylindrical offshore piles with both constant and linearly varying diameters utilizing computational fluid dynamics (CFD) simulations. The classical Morison equation is evaluated alongside an extended version to address limitations in predicting forces on geometrically complex structures. Mesh convergence studies are performed to select the optimum grid size for separate wave and current simulations. The focus is on test cases characterized by small Keulegan-Carpenter (KC) numbers and relatively high Reynolds (Re) numbers within both inertia-dominated and diffraction zones. Numerical simulation results are utilized to compare the force predictions of the classical Morison equation and the extended Morison equation. It is observed that the classical Morison equation performs adequately for constant diameter piles, but it fails to predict forces on variable diameter piles accurately. In contrast, the extended Morison equation, incorporating nonlinear effects and variable cross-sections, provides significantly more accurate force predictions, particularly in the diffraction zone compared to the numerical simulations. This study emphasizes the critical importance of accounting for geometric variations, such as linearly varying pile diameters, under separate waves and currents loadings in hydrodynamic force calculations. These considerations support the development of enhanced design methods and optimization strategies, leading to safer and more efficient offshore structures.

Physical modelling study on wave damping induced by an idealized floating kelp farm

A physical modelling study was carried out to investigate random wave damping promoted by an idealized floating kelp farm. The experimental conditions spanned intermediate water depths and both linear and nonlinear water waves. Unlike previous studies of wave damping promoted by vegetation, the floating kelp farm was placed close to the water surface with a ratio between vegetation height and water depth close to 0.25. The wave transmission coefficient induced by the floating kelp farm ranged between 0.56 and 0.96. This coefficient decreased for longer floating kelp farms and it was a function of the ratio between kelp farm length and incident wavelength and of the relative wave depth. Spectral analysis showed that wave damping was not frequency-dependent for wave frequencies close to the peak frequency. The wave transmission coefficients of a floating kelp farm with about 100 culture lines and with an extension of approximately 200 m were similar to those of submerged detached breakwaters with a relative crest freeboard smaller than -0.4. Furthermore, the bulk drag coefficient of near-surface idealized floating kelp farms can be modelled as a function of the Keulegan-Carpenter number. This study highlights the potential viability of nature-based solutions such as floating kelp farms for coastal protection.

An empirical tool for predicting the presence or absence of coseismic displacements at GNSS stations

Unmodeled displacements in GNSS times series, induced by instrumental artifacts or geophysical events, create significant biases in station trajectory parameters that can propagate into the reference frame itself. While non-tectonic ‘jumps’, such as equipment changes, affect only a specific GNSS station, seismically-induced displacements can affect large numbers of sites, severely threatening the frame’s stability. Manually reviewing individual GNSS time series for such effects is highly impractical because there can be thousands of GNSS stations in a frame, and the total number of earthquakes Mw ≥ 6.0 since GPS became fully operational is + 5100. To avoid this time-consuming task, automated methods rely on empirical power-law functions to determine which earthquake-station pairs require coseismic displacement parameters. Still, ‘conservative’ power-law functions tend to add coseismic offsets to stations that do not need them, which can also threaten the stability of the frame. In this work, we present an empirical formulation that was obtained using 809 global seismic events to fit power-law parameters that do not overestimate the region of influence of earthquakes. Our method is based on a two-level selection process: level 1 is isotropic and only considers the epicentral distance between the stations and the earthquake, and level 2 uses the geophysical parameters of the earthquake to predict a ‘tighter’ displacement pattern to select which stations require coseismic trajectory parameters. We applied our level 2 method to a database of ~ 4700 event-station pairs and showed that it removed ~ 55% of the total pairs, all of which had been falsely selected by level 1.

Molecular dynamics-based targeted adsorption of hazardous substances from rubberized asphalt VOCs by UiO-67

The interplay among UiO-67 and rubberized-asphalt components has been examined according to its molecular scale. The adhesion kinetics of UiO-67 to VOCs molecules in asphalt was modeled. The binding energy, radial distribution function (RDF), solubility parameters (SP), mean square displacement (MSD) and other parameters among UiO-67 to rubberized-asphalt components were evaluated in depth. The Sorption module was simulated the adsorption behavior of UiO-67 on 12 malodorous gases and 5 primary carcinogens. In combination with GC-MS results, the conjugative bonds and target attachment mechanisms for UiO-67 with VOCs were clarified. It was indicated that the binding energy among UiO-67 to the components were all negative. The radial distribution of asphalt was characterized as proximally ordered and remotely disordered. The ΔSP was less than 1.6, which was indicated that UiO-67 could be compatible with asphalt. The overall inhibition effect of UiO-67 on a group of carcinogens was exceeded 70 %. The presence of conjugation effect was allowed the adsorption sites of vinyl chloride and 1,3 butadiene to occur at high densities within the benzenoid. The concentration reduction of UiO-67 for hydrogen sulfide, carbon disulfide, and dimethyl sulfide was more than 80 %. The higher polarity was predisposed substances such as hydrogen sulfide and isobutanol to interact with the non-benzene ring region of UiO-67.

Deriving Ritz formulation for the Static Flexural Solutions of Sinusoidal Shear Deformable Beams

This paper presents the Ritz variational method for the static bending analysis of sinusoidal shear deformable beams. The theory accounts for transverse shear deformation and satisfies transverse shear stress-free conditions at the top and bottom surfaces of the beam. The total potential energy functional for the thick beam bending problem is formulated and minimized using a Ritz procedure. The problem considered simply supported boundary conditions and two cases of loading – uniformly distributed load over the span and point load at the center. The function is a function of two unknown displacement functions constructed in terms of unknown generalized displacement parameters and shape functions that satisfy the boundary conditions. Ritz minimization of the functional is used to find the generalized displacement parameters and then the displacements w(x) and The displacements and stresses are found for the loading distributions considered. It is found that the results obtained agree remarkably well with the exact results obtained using the theory of elasticity. The differences between the present results and the exact solutions are less than 0.3% for maximum transverse displacement for both cases of loading considered. For uniform load over the beam, the result for l/t = 10 is 0.112% greater than the exact solution. For the point load at the center, the result for l/t = 10 is 4.468% greater than the exact solution. The increased difference in the point load case is due to the singular nature of the point load problem.

Unraveling Superior Elasticity and Controlled Thermal Expansion in Trigonal MBO3 (M=Al, Ga) with Isolated [BO3] Group: A Theoretical Perspective

AbstractA comprehensive theoretical investigation employing density functional theory explores the electronic structure, temperature‐dependent elasticity, thermodynamic properties, and chemical bonding of trigonal MBO3 (M=Al, Ga) with isolated [BO3] groups. The results uncover MBO3 (M=Al, Ga) as indirect semiconductors with superior mechanical stability, characterized by greater resistance to volume compression over shear deformation. Their elasticity exhibits relatively weak temperature dependence, suggesting excellent thermal stability. Thermodynamic analysis predicts that GaBO3 has a higher thermal expansion coefficient than AlBO3, approximately 2.1×10−5 K−1 and 1.8×10−5 K−1 at 300 K, respectively. Significantly, the overall thermal expansion coefficients of GaBO3 and AlBO3 are lower compared to other borate materials containing isolated [BO3] groups. Chemical bonding insights reveal that GaBO3′s larger thermal expansion is attributed to its larger atomic displacement parameters and weaker Ga−O bond strength. This research positions MBO3 (M=Al, Ga) as prime candidates for optical device applications due to their well‐characterized elasticity and controlled thermal expansion.

Vestibular control of standing balance following 24h of sleep deprivation.

Sleep deprivation alters cognitive and sensorimotor function, but its effects on the control of standing balance are inconclusive. The vestibular system is critical for standing balance, and is modified by sleep deprivation; however, how sleep deprivation affects vestibular-evoked balance responses is unknown. Thus, this study aimed to examine the effect of 24h of sleep deprivation on the vestibular control of standing balance. During both a well-rested (i.e., control) and sleep deprivation condition, nine females completed two 90-s trials of bilateral, binaural stochastic electrical vestibular stimulation (EVS) and two 120-s trials of quiet stance on a force plate. Quiet stance performance was assessed by center of pressure displacement parameters. Mediolateral ground reaction force (ML force) and surface electromyography (EMG) of the right medial gastrocnemius (MG) were sampled simultaneously with the EVS signal to quantify vestibular control of balance within the frequency (gain and coherence) and time (cumulant density) domains. Twenty-four hours of sleep deprivation did not affect quiet stance performance. Sleep deprivation also had limited effect on EVS-MG EMG and EVS-ML Force coherence (less than control at 8-10.5Hz, greater at ~ 16Hz); however, gain of EVS-MG EMG (< 8, 11-24Hz) and EVS-ML force (0.5-9Hz) was greater for sleep deprivation than control. Sleep deprivation did not alter peak-to-peak amplitude of EVS-MG EMG (p = 0.51) or EVS-ML force (p = 0.06) cumulant density function responses. Despite no effect on quiet stance parameters, the observed increase in vestibular-evoked balance response gain suggests 24-h sleep deprivation may lead to greater sensitivity of the central nervous system when transforming vestibular-driven signals for standing balance control.

The effect of amplitude of heat flux on the adsorption of doxorubicin by MOF11 bio-carrier using molecular dynamics simulation

A common chemotherapy drug, doxorubicin's effectiveness is restricted by its quick excretion from the body and poor solubility. Because of their large surface area and adjustable pore size, bio MOF11 carriers demonstrated promise as drug delivery systems. Examining how external heat flux amplitude (EHFA) affects bio MOF11's ability to adsorb doxorubicin can reveal ways to improve drug loading and release, which will improve drug delivery. Moreover, by shortening the time needed for adsorption (Ads) and desorption, using EHFA in drug Ads processes can increase energy efficiency. Through comprehending the effect of EHFA on the Ads procedure, researchers can ascertain the ideal circumstances for optimizing drug loading while reducing energy usage. The current work examined the effect of EHFA amplitude on doxorubicin Ads via a bio MOF11 carrier using molecular dynamics (MD) modeling. According to MD data, EHFA was expected to have a significant effect on the atomistic evolution of the proposed drug-MOF11 system. The system's interaction energy (IE) and diffusion coefficient rose from −937.27 kcal/mol and 61.40 nm2/ns to −984.08 kcal/mol and 75.16 nm2/ns when EHFA changed from 0.01 to 0.05 W/m2. Increasing EHFA to 0.05 W/m2 resulted in a mean square displacement (MSD) parameter of 69.16 Å2. Therefore, based on the numerical results from this study, it can be said that the doxorubicin drug-MOF11 system changed and atomically evolved when the applied EHFA changes in magnitude.

Vortex-Induced Vibration (VIV) of flexible riser conveying severe slugging and straight flow in steady and oscillatory flows

This paper aims to investigate dynamic characteristics of Vortex-Induced Vibration (VIV) of a flexible riser conveying severe slug flow and straight flow in steady and oscillatory flows. Firstly, a classical wake oscillator model is adopted to simulate the coupling effects between internal and external flows on dynamic characteristics of VIV and an improved wake oscillator model is developed to calculate responses of VIV in oscillatory flow. A two-dimensional (2D) Computational Fluid Dynamics (CFD) model is developed to predict the behavior of severe slug flow. Then, structural equations of riser are discretized by adopting central difference method, and the Runge-Kuta method is adopted to solve them and the wake oscillator equations. The results show that characteristics of VIV, including root mean square (RMS) of displacement, dominant modes and vibration frequencies of riser conveying severe slugging differ significantly from those of riser conveying straight flow. New mode responses are triggered and multi-frequency phenomenon is observed due to severe slug flow. In addition, responses of VIV of riser conveying severe slug flow are influenced by the variation of the velocity or oscillation intensity of external flow. Model transition is normally triggered with a high-velocity sheared flow or a high Keulegan-Carpenter (KC) number.

Viscous effects on the hydrodynamic performance of a two-body wave energy converter with a damping plate

In this study, the hydrodynamic forces and power absorption performance of an autonomous underwater vehicle (AUV)-based two-body wave energy converter (2BWEC) are investigated. A theoretical model is developed within the framework of linear potential flow to solve for added mass, radiation damping, and wave excitation force using the matched eigenfunction expansion method (MEEM). A computational fluid dynamics (CFD) model is employed to account for vortex-shedding effects of the floater and inner cylinder with a damping plate under various excitation conditions. Empirical formulas for supplementary added mass and drag coefficients caused by flow separation are proposed based on curve-fitting the differences between CFD results and MEEM calculations. These formulas are integrated into motion equations to enhance accuracy in evaluating the power absorption of the 2BWEC. It has been found that in the context of viscous flow, both the added mass and damping coefficients are increased, particularly for the inner cylinder with a damping plate. In addition, the viscous hydrodynamic coefficients exhibit strong dependence on the Keulegan–Carpenter number, while showing insensitivity to changes in the frequency parameter β. The supplementary (viscous) added mass provides additional inertia for the AUV with a limited mass itself, which is advantageous for the power absorption of the AUV-based 2BWEC. Conversely, the presence of viscous damping from the damping plate impedes wave energy capture.

Continuous-Flow Synthesis of Zn1-xMnxS Nanoparticles at Ambient Conditions.

With its large direct band gap and good chemical stability, ZnS is suitable for many applications, including light-emitting diodes, panel displays, and photodetection. Here, nanoparticles of ZnS are synthesized phase pure under ambient conditions by precipitation in a simple and scalable continuous-flow reactor. Furthermore, different degrees of Zn substitution with Mn have been investigated, Zn1-xMnxS, with x = 0.05, 0.19, and 0.25 according to X-ray fluorescence measurements. The products are analyzed with multitemperature synchrotron powder X-ray diffraction (PXRD) and X-ray total scattering. The analysis reveals phase-pure synthesis products with the sphalerite structure and crystallite sizes in the range of 3.8-4.7 nm in agreement with scanning transmission electron microscopy. Only Zn0.75Mn0.25S shows traces of Mn3O4, indicating that x = 0.25 is above the substitution limit as the impurity appears. Substitution of Zn with Mn in the nanoparticles is confirmed by energy-dispersive X-ray spectroscopy, as well as an observed decrease in the band gap, decrease in the sphalerite-to-wurtzite phase transition temperature, and increase in the unit cell dimensions with increasing Mn content. Based on the modeling of the PXRD Rietveld refined atomic displacement parameters, the Debye temperature for ZnS and Zn0.95Mn0.05S is determined to be 322 ± 13 and 394 ± 22 K, respectively.

Bilateral hip stability variation in the functional ambulation and kinetic parameters after total hip arthroplasty during leveled walking.

This study determines gender variation, comparing the significance level between men and women related to functional ambulation characteristics after hip arthroplasty. The study focuses on the broader female pelvis and how it affects the rehabilitation regimen following total hip arthroplasty. In this cross-sectional study, 20 cases of right hip arthroplasty were divided into 10 male and 10 female cases, aged 40-65years. The functional ambulation parameters (walking cadence, gait speed, stride length, and gait cycle time) were acquired from the GAITRite device, as well as kinematic values for hip frontal plane displacement and kinetic parameters for ground response force in the medial-lateral direction. An independent t-test showed a significant difference in the kinematic parameter variables for the anterior superior iliac spine, more significant trochanter displacement, and hip abduction angle between the operated and non-operated limbs for each group separately. Regarding the functional ambulation parameters, there was a significant difference in the walking cadence between the operated and non-operated limbs of both male and female groups. Moreover, the output variables of ground reaction force measures revealed significant differences between their operated and non-operated limbs. The linear regression model used was consistent with the current results, demonstrating a weak negative correlation between the abduction angle of the operated hip and gait speed for both male and female groups. Based on the findings, we draw the conclusion that improving a rehabilitated physical therapy program for the abductors of both male and female patients' operated and non-operated limbs is essential for normalizing the ground reaction force value, avoiding focus on the operated hip, and reducing the amount of time that the operated hip's abductors must perform. This involves exposing the surgically repaired limb to the risk of post-operative displacement or dislocation, particularly in female patients.

Negative thermal expansion in hexagonal VF3 predicted by first-principles calculation

Abstract Searching negative thermal expansion (NTE) materials is challenging. Herein, hexagonal VF3 is predicted as a new NTE material for the first time. VF3 displays NTE property in the temperature range from 0 to 380 K, and the minimum NTE coefficient(α) is approximately −4.68 × 10−6 K−1 at 120 K. The NTE mechanism was ascribed to the vibrations of F atom with larger atomic displacement parameters, which dominates the negative Grüneisen parameters. The difference of minimum NTE coefficient between VF3 and TiF3 might be caused by their different chemical bond strength between Ti–F and V–F. This research provides a deeper understanding between NTE and crystal structure.

A refined model for functionally graded graphene nanoplatelets reinforced composite beams under thermal loads

Graphene is highly regarded as a promising material for various engineering purposes due to its remarkable physical characteristics. However, existing higher-order shear deformation theories may struggle to accurately capture the interlaminar mechanical response of functionally graded graphene nanoplatelets (FG-GNP) reinforced composite beams subjected to thermal loads. This arises from the pronounced discrepancies in material properties and thermal expansion coefficients among the various layers, making the interlaminar mechanical behavior of composite structures exceedingly complex under thermal loading. As a result, a meticulous analysis of interlaminar stresses becomes necessary for the structural assessment of GNP-reinforced composite beams under temperature variations. To overcome this limitation, we propose an advanced model incorporating transverse normal thermal deformation, tailored specifically for FG-GNP reinforced composite beams subjected to thermal loads. The developed model primarily boasts two advantages. Firstly, although transverse normal deformation is introduced into the displacement field, no additional displacement variables are increased, thereby maintaining model simplicity and efficiency. Secondly, the model achieves a high-precision interlaminar shear stress field taking into account the interlaminar continuity conditions and temperature effects. Furthermore, the elimination of second-order derivatives of in-plane displacement parameters from the transverse shear stress components leads to a simplification in the finite element implementation. Based on the proposed model, a simple three-node beam element is constructed. The 3D elasticity solutions and the results from alternative modeling frameworks are used to assess the performance of the developed model. Additionally, a comprehensive investigation is conducted to explore the effects of various parameters on the deformations and stresses of GNP-reinforced composite beams.

Fault diagnosis of railway freight car rolling bearings based on ACMD and improved MCKD

To address the issue of accurately extracting fault characteristic information of railway freight car bearings under noisy conditions, this paper proposes a fault diagnosis method based on Adaptive Chirp Mode Decomposition (ACMD) and an optimized Maximum Correlation Kurtosis Deconvolution (MCKD) using a Sparrow Search Algorithm Combining Sine-Cosine and Cauchy Mutation (SCSSA). Firstly, ACMD is used to decompose and reconstruct the original fault signal to obtain several Intrinsic Mode Functions (IMFs). Then, the IMFs are filtered according to the Gini coefficient indicator, with the IMF having the largest Gini coefficient selected as the optimal component. Secondly, the SCSSA is employed to iteratively optimize the filter length L, fault signal period T, and displacement parameter M in the MCKD algorithm, determining the optimal parameter combination for MCKD. This avoids the limitations of manual settings and enhances the accuracy of fault diagnosis. The optimized MCKD is then applied to the optimal component, and deconvolution is performed using maximum correlation kurtosis as the criterion to extract fault characteristic information through its envelope spectrum. To verify the effectiveness and generalizability of the proposed method, simulations, experimental signals from the Case Western Reserve University Bearing Center, and actual measured signals from railway freight car bearing 353130B are used to analyze inner ring faults. The experimental results demonstrate that the method can accurately extract fault characteristic information of railway freight car bearings under noise interference and identify the fault type.

Coupled topological rainbow trapping of elastic waves in two-dimensional phononic crystals

Rainbow trapping, observed in elastic waves, has attracted considerable scientific interest owing to its potential applications in energy harvesting, buffering, and wavelength-division multiplexing devices. However, previous approaches have often necessitated complex geometric modifications to the scatterer, such as altering dimensions or shifting along diagonals to corners, limiting practical utility. Here, we realize the coupled topological edge states (CTESs) of elastic waves in a two-dimensional (2D) solid phononic crystal (PC) with inversion center changes. Changing the inversion center along the x or y directions by a specific distance can induce the topological phase transition. The topological edge states (TESs) arise at the interface by combining PCs with different topologies positioned adjacent to each other. Furthermore, it is demonstrated that TES exhibits topological robustness against defects. By introducing a gradient into the PC structure by altering the geometrical parameters of scatterers along the interface, the topological rainbow trapping of elastic waves is achieved. Finally, the CTES are generated by the interaction between TESs of different interfaces, which can lead to coupled topological rainbow trapping in phononic heterostructures with different displacement parameters along the multiple interface gradient. Our results pave the way for manipulating the symmetric and antisymmetric topological modes of elastic waves in topologically coupled waveguides, which offers potential applications in selective filtering and multiband waveguiding.