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The present paper is concerned with nonlinear vibration of a simply supported functionally graded graphene reinforced composite (GRC) cylindrical panel subjected to the transverse excitation. Functionally graded structure is proposed to distribute more graphene platelets (GPLs) to the most needed layer for the optimal performance. The modified Halpin-Tsai model and the rule of mixture are carried out to predict the effective material properties of the GRC cylindrical panel, such as Young's modulus, Poisson's ratio and mass density. Nonlinear partial differential equations of motion are established within the framework of Hamilton principle in conjunction with first-order shear deformation theory (FSDT) and von Karman geometric nonlinearity. Navier approach is adopted to calculate natural frequencies of the GRC cylindrical panel. Then, considering the external excitation, Galerkin method is applied to realize the model reduction, which is expressed by the ordinary differential equations. Backward Differentiation Formula (BDF) is used to perform nonlinear transient responses of the system subjected to the pulse excitation (step load or triangular load). Finally, Runge-Kutta method is employed to carry out bifurcations and chaotic dynamics of the system subjected to the steady-state excitation. Results are presented in the form of natural frequencies and nonlinear responses to perform the parametric studies, such as distribution types and weight fractions of GPLs, geometry parameters and excitation parameters of the GRC cylindrical panel.

BACKGROUND: Atrial fibrillation (AF) relapse following radiofrequency catheter ablation (RFCA) for persistent atrial fibrillation (PeAF) continues to be a concern. This study establishes a connection between left atrial appendage peak flow velocity (LAAV) and recurrence of AF in individuals having PeAF following first RFCA. METHODS: We retrospectively studied 164 successive PeAF patients who had first RFCA between January 2018 and December 2019. Before the ablation, the LAAV was recorded using transesophageal echocardiography (TEE). The demographic and clinical data of the individuals were gathered. Participants were monitored at regular intervals to monitor for recurrence of AF. We employed Cox proportional hazards regression to determine if LAAV, as well as other clinical indicators, were predictive of AF recurrence in follow-up. RESULTS: In this study, AF relapse was seen in 43 patients (26.2%) following a median follow-up of 15 [interquartile range (IQR): 12–18] months. It was shown that the LAAV was decreased in individuals who had recurrences of AF (0.36±0.05 vs. 0.45±0.17 m/s, P=0.004). Using Kaplan-Meier analysis, it was discovered that the low LAAV (0.37 m/s) group had a poorer event-free survival rate compared to the high LAAV (>0.37 m/s) group (17.6 vs. 21.2 months, log-rank P=0.002) group. Based on the results of the multivariate Cox regression analysis, a LAAV of fewer than 0.37 m/s [hazard ratio (HR): 2.32; 95% confidence interval (CI): 1.177–4.227; P=0.014] was shown to be an independent predictor of AF recurrence following RFCA. CONCLUSIONS: A low LAAV is associated with AF relapse, and it is a predictor of AF relapse following the first RFCA for PeAF. This discovery may be useful in the optimization of treatment strategies and the care of patients with PeAF.

Mitral valve surgery combined with atrial fibrillation (AF) radiofrequency ablation (AFRA) is recommended as the first-line strategy for valvular disease-related AF. There are relatively few reports on the effect of AFRA combined with total thoracoscopic mitral valve surgery. This article aimed to analyze the clinical data and prognostic outcomes of patients with diverse left atrium diameter (LAD) (50 or ≤50 mm) who underwent total thoracoscopic mitral valve surgery combined with AFRA.We conducted a prospective analysis of patients who underwent AFRA from January 2021 to June 2022 in the Department of Cardiovascular Surgery at the Chinese PLA General Hospital. The inclusion criteria were: (I) aged 40-70 years; (II) diagnosed with valvular heart disease and concomitant long-term persistent AF (1 year); (III) patients who underwent total thoracoscopic mitral valve surgery; (IV) with a left ventricular end-diastolic diameter of ≤70 mm; (V) with a LAD ≤65 mm; and (VI) left ventricular ejection fraction (LVEF) ≥50%. The included patients were assigned to group A and B depend up on the LAD. All patients were followed up at 3 and 6 months timepoints postoperatively. The prime endpoint was the recovery rate of sinus rhythm.There were 24 cases in group A (LAD50 mm) and 16 cases in group B (LAD ≤50 mm). The two groups exhibited no statistical differences in terms of age, gender proportion, preoperative comorbidities, AF duration, preoperative heart function, and type of valve disease (P0.05). The LAD, pulmonary artery pressure, and left ventricular diameter of group A were significantly greater than those of group B (P0.05). There were no new cerebrovascular incidents during the perioperative and follow-up periods. The sinus rhythm conversion rates in group A after surgery and at 6 months were 75% and 66.7%, respectively; meanwhile, both of these values were 87.5% in group B, and the difference between the groups was statistically significant (P0.05).Total thoracoscopic mitral valve surgery with AFRA is more effective in maintaining sinus rhythm in patients with LAD ≤50 mm than in those with LAD50 mm without increased risk of adverse events. Further studies are warranted to validate our findings.

Objective: To investigate the molecular mechanism and simulated validation of Zhi Bai Di Huang Pill (ZBDHP) for the treatment of systemic lupus erythematosus (SLE) using network pharmacology and molecular docking techniques. Methods: The active ingredients of ZBDHP were obtained through the TCMSP database and the Canonical SMILES of the active ingredients were queried through Pubchem. The targets of the active ingredients were predicted in the SwissTarget database based on the SMILES. The SLE-related disease targets were obtained through the GeneCards, OMIM and DisGenets databases, and the intersection targets of ZBDHP and SLE were obtained using the Venny 2.1.0 online platform. Intersection targets build a visual protein interaction network (PPI) through the STRING database, and the core targets were identified by network topology analysis. GO analysis and KEGG pathway enrichment analysis of the intersecting targets were performed using the DAVID database. Finally, the molecular docking of the first four active ingredients and the first four core target genes were verified by Pubchem, the PDB database and CB-Dock online molecular docking technology. Results: ZBDHP screened 91 potential active ingredients and 816 potential targets. Among them, 141 genes were intersected by ZBDHP and SLE. The network topology analysis showed that the main active ingredients were Hydroxygenkwanin, Alisol B, asperglaucide, Cerevisterol, etc., and the key target genes were TNF, AKT1, EGFR, STAT3, etc. GO and KEGG enrichment analysis showed that common targets interfere with biological processes or molecular functions such as signal transduction protein phosphorylation, inflammatory response, transmembrane receptor protein tyrosine kinase activity, etc., through multiple signaling pathways, such as pathways in cancer, Kaposi sarcoma-associated herpesvirus infection, the PI3K-Akt signaling pathway, lipid and atherosclerosis, hepatitis B, etc. Molecular docking results showed that the active components of ZBDHP have good binding activity to the core targets of SLE. Conclusions: This study reveals that the ZBDHP treatment of SLE is a complex mechanistic process with multi-components, multi-targets and multi-pathways, and it may play a therapeutic role in SLE by inhibiting the production, proliferation and apoptosis of inflammatory factors. In conclusion, the present study provides a theoretical basis for further research on ZBDHP.

In this work, the graphene composite sheets coated with metal were equivalent to composite laminated sheets. The nonlinear coupling vibrations of graphene composite laminated sheets (GCLSs) under particle impact were investigated. The size-dependent effect and viscoelasticity were incorporated to model GCLSs in the nonlocal continuum theory and Kelvin-Voigt model framework. Particle impact was regarded as stochastic excitation on the GCLS. According to the von Karman strain-displacement relationship for the geometric nonlinearity and Reddy's third-order shear deformation plate theory, the nonlinear governing partial differential equations were derived. To examine the validity of this model, a comparison with published results was carried out. With the purpose of ensuring the convergence and reliability of the results, a large number of mode truncations were performed. The emphasis of numerical simulations was placed on studying how the various factors, including the size-dependent effect, forcing amplitude, and viscoelasticity, influencing the nonlinear responses of GCLS. The motivation of this study is to present a novel model providing both practical and theoretical guidance for devices involving graphene composites subjected to particle impacts.

Turbo-machineries, as key components, have a wide utilization in fields of civil, aerospace, and mechanical engineering. By calculating natural frequencies and dynamical deformations, we have explained the rationality of the series form for the aerodynamic force of the blade under the subsonic flow in our earlier studies. In this paper, the subsonic aerodynamic force obtained numerically is applied to the low pressure compressor blade with a low constant rotating speed. The blade is established as a pre-twist and presetting cantilever plate with a rectangular section under combined excitations, including the centrifugal force and the aerodynamic force. In view of the first-order shear deformation theory and von-Kármán nonlinear geometric relationship, the nonlinear partial differential dynamical equations for the warping cantilever blade are derived by Hamilton’s principle. The second-order ordinary differential equations are acquired by the Galerkin approach. With consideration of 1:3 internal resonance and 1/2 sub-harmonic resonance, the averaged equation is derived by the asymptotic perturbation methodology. Bifurcation diagrams, phase portraits, waveforms, and power spectrums are numerically obtained to analyze the effects of the first harmonic of the aerodynamic force on nonlinear dynamical responses of the structure.

The 2019-nCoV is ravaging the world, taking lots of lives, and it is emergent to find a solution to deal with this novel pneumonia. This paper provides a potential treatment for COVID-19 utilizing resonance to destroy the infection ability of 2019-nCoV. Firstly, the geometry size of 2019-nCoV is scaled up by 10,000 times. The additional mass is used to represent the effect of the fluid around a spike protein. The finite element analysis (FEA) is used to study the modal characteristics of the tuned 2019-nCoV model and mistuned 2019-nCoV model in blood, respectively. Based on FEA, the lumped parameter mechanical model of 2019-nCoV is established. Then, the dynamic responses of mistuned 2019-nCoV are investigated through harmonic response and dynamical analysis. Finally, a potential method utilizing 360° sweep excitation to cure COVID-19 is put forward.

Piezoelectric vibration energy harvesting has attracted considerable attention because of its prospects in self-powered electronic applications. There are a many low-velocity waters in nature, such as rivers, seas and oceans, which contain abundant hydrokinetic energy. In this paper, an optimal geometric piezoelectric beam combining magnetic excitation is identified and applied to a vortex-induced vibration energy harvester (ViVEH) for low velocity water flow, which is composed of a continuous variable-width piezoelectric beam carrying a cylindrical bluff body. The finite element simulation and experiment are first carried out to study the harvesting characteristics of the designed variable-width beam ViVEH without considering the magnetic excitation. The influence of the width-ratio and flow velocity on the harvesting voltage is studied in detail. The optimal structure, a ViVEH equipped with triangular piezoelectric beam, is then obtained by the superior energy harvesting performance for low velocity water flow. From the experimental results, at a flow velocity of 0.6 m/s, the highest root mean square (RMS) voltage and RMS voltage per unit area are 19.9 V and 0.07 V/mm2, respectively. Furthermore, magnetic excitation is introduced to improve the scavenging performance of the optimal triangular beam ViVEH, different polarity arrangements are compared, and the optimal case, the arrangement of horizontal repulsion and vertical attraction (HR-VA), is obtained. This case can scavenge the highest power of 173 μW at a flow velocity of 0.5 m/s, which is increased by 127% compared to a conventional constant-width beam ViVEH with no magnetic excitation.

PurposeThis study identifies a new type of advertising, sponsored ad forwarding, in microblog contexts. It tests the effectiveness of designs of a message with an ad with regard to receivers who are purely online friends or offline friends.Design/methodology/approachIn the main experiment, a three-by-two experimental design was employed. By random assignment, message senders forwarded an ad with either an other-oriented or a self-oriented message to a group of offline friends or purely online friends. In the control group, there was no message accompanying the ad. The data of 218 effective sender-receiver dyads were collected and compared.FindingsThe results show that a message with an other-oriented appeal is more effective than one with a self-oriented appeal for dyads with an offline relationship, and a message with a self-oriented appeal is more effective than one with an other-oriented appeal for dyads with a purely online relationship. Overall, the use of appeals significantly boosts ad effectiveness.Originality/valueThis study identifies a new type of marketing practice in social media, namely sponsored ad forwarding. It also proposes appeal orientation as a novel type of message content design. It shows how to apply the right appeal orientation to the right receiver groups, that is, offline or purely online friends.

This paper focuses on the derivation of the aerodynamic force for the cantilever plate in subsonic flow. For the first time, a new analytical expression of the quasi-steady aerodynamic force related to the velocity and the deformation for the high-aspect-ratio cantilever plate in subsonic flow is derived by utilizing the subsonic thin airfoil theory and Kutta-Joukowski theory. Results show that aerodynamic force distribution obtained theoretically is consistent with that calculated by ANSYS FLUENT. Based on the first-order shear deformation and von Karman nonlinear geometric relationship, nonlinear partial differential dynamical equations of the high-aspect-ratio plate subjected to the aerodynamic force are established by using Hamilton’s principle. Galerkin approach is applied to discretize the governing equations to ordinary differential equations. Numerical simulation is utilized to investigate the relation between the critical flutter velocity and some parameters of the system. Results show that when the inflow velocity reaches the critical value, limit cycle oscillation occurs. The aspect ratio, the thickness, and the air damping have significant impact on the critical flutter velocity of the thin plate.

This paper presents an experimental study of the broadband energy harvesting and dynamic responses of an L-shaped piezoelectric cantilever beam. Experimental results show that the L-shaped piezoelectric beam generates two optimal voltage peaks when the horizontal beam size is similar to the vertical beam size. Several optimized L-shaped piezoelectric cantilever beam structures are proposed. Power generation using the inverted bistable L-shaped beam is better. It is observed experimentally that the inverted bistable L-shaped beam structure shows obvious bistable characteristics and hard spring characteristics. Furthermore, the corresponding relationship between the bistable phase portrait and the potential energy curve is found in the experiment. This is the first time that a phase portrait for stiffness hardening of an L-shaped beam has been found experimentally. These results can be applied to analysis of new piezoelectric power generation structures.

This paper develops a new structure dynamic model to investigate nonlinear transient responses of the rotating blade made of functionally graded material (FGM). The rotating blade is simplified as a rotating FGM cylindrical panel with a presetting angle and a twist angle. The geometric nonlinearity effects are taken into account in the strain-displacement relationships, which are derived by Green strain tensor. Based on the first-order piston theory and the first-order shear deformation theory, the equations of motion for the rotating twisted FGM cylindrical panel are acquired by means of Hamilton principle and Galerkin method. Backward Differentiation Formula (BDF) and Runge-Kutta Algorithm are used to solve the nonlinear equations of motion for the system. The effects of four pulse load conditions on the system subjected to the internal pulse load or the external pulse load are fully discussed. A detailed parametric analysis is performed by considering the effects of the rotating speed, volume fraction index and temperature.

Vibration energy harvesting has attracted considerable attention because of its application prospects for charging or powering micro-electro-mechanical system. Abundant hydrokinetic energy of water at low velocity is contained in the fluid environment, such as rivers and oceans, which are widely existing in nature. In this paper, a flow-induced piezoelectric vibration energy harvester (PVEH) with magnetic force enhancement, which is integrated by piezoelectric beam, circular cylinder bluff body and magnets, is proposed and experimental investigated. It could transfer the hydrokinetic energy, both the vortex-induced vibration and magnetic force excitation underwater, into electricity. First, the frequency sweep experiment of the piezoelectric cantilever beam is carried out to determine the resonance frequency where the effect of magnetic force on the vibration characteristic is obtained. Furthermore, the flow-induced vibration experiment platform is setup and the energy harvesting performance of the PVEH is investigated in detail. The effects of the magnet property, flow velocity and the magnetic poles distance on the vibration frequency and the acquisition voltage are demonstrated and discussed. The results show that it could improve the harvesting performance by introducing magnetic force. It has advantages in higher output voltage for the flow-induced PVEH, especially in low velocity water flow, when the flow velocity is 0.35 m/s, the PVEH under attractive magnetic force with magnetic distance of 20 mm scavenges the higher acquisition voltage of 5.2 V, which is increased by 225% than the PVEH with non-magnetic. The results can be applied to guide further fabrication process and optimized design of the proposed flow-induced PVEH underwater with low flow velocity.

Machine-vision technology has progressed remarkably in both accuracy and speed owing to advances in computer technology and artificial intelligence. In this paper, state-of-the-art research on vision-based techniques is reviewed for civil infrastructure condition assessment. The major challenges of machine vision technique in civil structural health monitoring are presented.

Background: Recurrence after Radiofrequency catheter ablation（RFCA） of persistent atrial fibrillation (PeAF) is still elusive. The present study aimed to evaluate the relationship between the left atrial appendage peak flow velocity(LAAV) and atrial fibrillation(AF) recurrences in PeAF patients after their initial RFCA. Method: This study included 164 consecutive PeAF patients who performed initial RFCA from January 2018 to December 2019. Transesophageal echocardiography was used to collect the LAAV before ablation. Patients’ demographic and clinical information was gathered. To detect the recurrences of AF, patients were checked up at routine intervals. A Cox proportional hazards regression analysis was adopted to evaluate the LAAV and other clinical variables as predictors of AF recurrences throughout follow-up. Results: AF recurrence resulted in 43 (26.2%) patients after a median follow-up of 15 months (IQR: 12-18 months). LAAV reduced in patients with AF recurrences (0.36±0.15m/s vs. 0.45±0.17m/s, P = 0.004). A Kaplan-Meier study revealed that the low LAAV(≤0.37m/s) group had a lower event-free survival rate than the high LAAV (>0.37m/s) group (17.6 months vs. 21.2 months, Log Rank P = 0.002). LAAV≤0.37m/s (HR 2.32, 95%CI 1.177-4.227, P = 0.014) was found to be independent predictors of AF recurrence after RFCA in the multivariate Cox regression. Conclusion: A low LAAV is linked to AF recurrence and acts as a predictor of AF recurrence after the initial RFCA of peAF. This would aid in treatment strategy optimization and management of patients with peAF.

Although the stability of the sandwich structures under in-plane excitation has been reported, few of them focus on the functionally graded materials (FGM) sandwich doubly curved shallow shells. Moreover, for the study of static bifurcation, stability and dynamic stability analysis, it is common to ignore the effect of thickness tension or compression. The purpose of this paper is to explore the bifurcation and stability of the FGM sandwich doubly curved shallow shell which is subjected to the in-plane excitation in thermal environment . By introducing the secant function to the transverse displacement, a new displacement field based on the Reddy’s third order shear deformation theory is derived. It is assumed that the material properties of sandwich doubly curved shallow shell are temperature dependent. The distribution of component materials in FGM layer obeys the rule of power law in the radial direction . Considering the geometric nonlinear, using an energy approach and the Galerkin’s method, a two-degree-of-freedom non-autonomous nonlinear dynamic equation with parametric excitation is derived. The threshold of the bifurcation and the stability of the structure are investigated. The instability regions are plotted by dynamic load factor against excitation frequency in α 1 - Ω plane.

Axially functionally graded (AFG) beams, with variable coefficients in the governing equation, are a novel class of composites structures that have continuous variations in material properties from one component to another. In this paper, the asymptotic development method (ADM) is utilized to investigate the free vibration of uniform AFG beams with different boundary conditions. By decomposing the variable flexural stiffness and mass per unit length into reference invariant parts and variant parts, perturbation theory is introduced to obtain an approximate formula of the natural frequencies of the uniform AFG beams. The numerical results of the proposed method are confirmed by comparing the obtained results with those obtained via finite element analysis and the published literature results, the comparison reveals the proposed method yields an accurate estimate of the first three order natural frequencies of the AFG beam. Moreover, the influences of the gradient parameter and support conditions on the first three natural frequencies are discussed. The proposed analytical method is simple and efficient and can be used to conveniently analyze uniform AFG beams with arbitrary changes in the material properties along the axial direction.

The effects of an internal nonlinear energy sink (NES) on a truss core sandwich plate in dynamics are investigated. The energy dissipation of the NES is studied with the sandwich plate excited by a half-wave shock. It is found that exceptional vibration absorption is achieved by the NES. Moreover, the relative motion between the sandwich plate and the NES remains in the acceptable range of the hollow truss core until the shock amplitude becomes too large. The slow flow equation and the frequency response of the system are obtained by employing the complexification-averaging method. Although the NES exhibits excellent performance when the sandwich plate is under an excitation with a relatively small amplitude, the efficiency is gradually diminished with the emergence of a stable higher branch and the merging of higher and lower branches. During the entire process, the NES does not collide with the face sheet of the sandwich plate. Further, the variation of vibration absorption performance of the NES with the increase of strut radius is investigated. It is demonstrated that the variation of the strut radius has a greater influence on the vibration absorption with a harmonic load in comparison to absorption with a shock load .

This paper presents the study on the chaotic wave and chaotic dynamics of the nonlinear wave equations for a simply supported truss core sandwich plate combined with the transverse and in-plane excitations. Based on the governing equation of motion for the simply supported sandwich plate with truss core, the reductive perturbation method is used to simplify the partial differential equation. According to the exact solution of the unperturbed equation, two different kinds of the topological structures are derived, which one structure is the resonant torus and another structure is the heteroclinic orbit. The characteristic of the singular points in the neighborhood of the resonant torus for the nonlinear wave equation is investigated. It is found that there exists the homoclinic orbit on the unperturbed slow manifold. The saddle-focus type of the singular point appears when the homoclinic orbit is broken under the perturbation. Additionally, the saddle-focus type of the singular point occurs when the resonant torus on the fast manifold is broken under the perturbation. It is known that the dynamic characteristics are well consistent on the fast and slow manifolds under the condition of the perturbation. The Melnikov method, which is called the first measure, is applied to study the persistence of the heteroclinic orbit in the perturbed equation. The geometric analysis, which is named the second measure, is used to guarantee that the heteroclinic orbit on the fast manifold comes back to the stable manifold of the saddle on the slow manifold under the perturbation. The theoretical analysis suggests that there is the chaos for the Smale horseshoe sense in the truss core sandwich plate. Numerical simulations are performed to further verify the existence of the chaotic wave and chaotic motions in the nonlinear wave equation. The damping coefficient is considered as the controlling parameter to study the effect on the propagation property of the nonlinear wave in the sandwich plate with truss core. The numerical results confirm the validity of the theoretical study.

In this paper, a simplified model of the bistable piezoelectric cantilever beam with magnets is established, and the potential energy of the bistable system is analyzed. We have proposed the bistable L-shaped beam structure, which has the same geometry dimensions of the bistable straight beam in the first time. The comparative study on power generations and dynamic responses of the bistable straight beam and the bistable L-shaped beam plays an important role in exploring excellent piezoelectric generator. The experiment structure includes the base layer and the piezoelectric layer. The harmonic excitation is given to the system. Theoretical analysis results show that the potential energy function of the system has two obvious steady potential wells. In addition, the depth of the upper potential well is different from that of the lower potential well when the gravity potential energy is considered. Experimental results demonstrate that the power generation for the straight beam is better than that of the horizontally placed L-shaped beam when the excitation amplitude is 450 mV. There is the existence that the energy harvesting capacity of the bistable L-shaped beam is better than that of the bistable straight beam when the excitation amplitude is 400 mV. Furthermore, the power generation of the bistable L-shaped beam with the upper potential well is obviously better than that of the bistable L-shaped beam with the lower potential well. In addition, comparing with the straight beam, the dynamic response of the bistable L-shaped beam is more complex when the external excitation frequency is changed. It is also observed that the distance between the magnets has the obvious influence on the dynamic response of the bistable system. It is very effective to select the appropriate distance between the magnets to improve the power generation of the bistable energy harvester under the fixed excitation conditions.

Nonlinear forced vibrations and natural frequency of sandwich functionally graded material doubly curved shallow shell with a rectangular base are investigated. The sandwich functionally graded material (FGM) doubly curved shell is subjected to a harmonic point load at centre. The sandwich doubly curved shell with homogeneous face sheets and FGM face sheets is considered respectively when the natural frequencies are studied. Reddy’s third order shear deformation theory is expanded in which stretching effects in thickness are considered by introducing the secant function. Hamilton’s principle and von-Karman type nonlinear geometric equation are applied to obtain partial differential equation of the FGM sandwich doubly curved shell. Comparative studies with other shear deformation theories are carried out to validate the present formulation. Navier method is used to discuss the natural vibration frequencies of the FGM sandwich doubly curved shell. Numerical simulation is applied to demonstrate the nonlinear dynamic responses of the FGM sandwich doubly curved shell. Multiple periods, quasi-period and chaos are detected for the dynamic system for different core thickness.

High speed rotating blades are crucial components of modern large aircraft engines. The rotating blades under working condition frequently suffer from the aerodynamic, elastic and inertia loads, which may lead to large amplitude nonlinear oscillations. This paper investigates nonlinear dynamic responses of the blade with varying rotating speed in supersonic airflow. The blade is simplified as a pre-twist and presetting cantilever composite plate. Warping effect of the rectangular cross-section of the plate is considered. Based on the first-order shear deformation theory and von-Karman nonlinear geometric relationship, nonlinear partial differential dynamic equations of motion for the plate are derived by using Hamilton’s principle. Galerkin approach is applied to discretize the partial differential governing equations of motion to ordinary differential equations. Asymptotic perturbation method is exploited to derive four-degree-of-freedom averaged equation for the case of 1 : 3 internal resonance-1/2 sub-harmonic resonance. Based on the averaged equation, numerical simulation is used to analyze the influence of the perturbation rotating speed on nonlinear dynamic responses of the blade. Bifurcation diagram, phase portraits, waveforms and power spectrum prove that periodic motion and chaotic motion exist in nonlinear vibration of the rotating cantilever composite plate.

As a crucial method in organizational and social behavior research, self-report surveys must manage method bias. Method biases are distorted scores in survey response, distorted variance in variables, and distorted relational estimates between variables caused by method designs. Studies on method bias have focused on post hoc statistical control, but integrated analyses of the sociopsychological mechanism of method bias are lacking. This review proposes a framework for method bias and offers a relatively complete and detailed review of the sociopsychological and statistical mechanisms of four main types of method bias and their procedural remedies. This review proposes “reduce, remove, and rectify” as a guideline for researchers in survey design to address method bias. Finally, this review presents two directions for future methodology research.

A piezoelectric impact cantilever in the bridge and a self-powered low power management circuit with stable output voltage matched with a mechanical model are presented in this paper. Based on the piezoelectric effect, the low-frequency mechanical vibration is converted into high-frequency electrical signal oscillation. The generated voltage preserves into the low-power constant-voltage power management circuit, which can effectively store electric energy. The equivalent circuit model of vibration for a piezoelectric impact cantilever is obtained. The key of energy management circuit is to improve energy storage efficiency. When impedance matching is achieved, the efficiency is maximum. Since the equivalent impedance of piezoelectric material is different in the impact process and natural vibration process, this paper uses the delay link and D-trigger to form the peak detection circuit, which can distinguish two vibration processes. So different duty cycles are generated to control the buck-boost circuit to achieve adaptive impedance matching. It can be found that the efficiency reached more than 80 %. Compared with the traditional energy management circuit, the efficiency is increased by 18 %.

A rotating cantilever sandwich-plate model with a pre-twisted and pre-set angle has been developed to investigate the vibrational behavior of an aero-engine turbine blade with thermal barrier coating (TBC) layers. The classic von Karman plate theory and the first-order shear deformation theory are applied to derive the energy equations of the rotating TBC blade, in which the geometric shapes, the work ambient temperature, and the TBC material properties are considered. The Chebyshev-Ritz method is used to obtain the nature frequency of the rotating TBC blade. For static frequency and modal analysis, the finite-element method (FEM) is also applied to compare and validate the results from the Chebyshev-Ritz method. A good agreement is found among these kinds of methods. For dynamic frequency, the results are analyzed in detail concerning the influence of system parameters such as the thickness of the TBC layer, the working temperature, and the pre-twisted and pre-set angle. Finally, the Campbell diagram is demonstrated to analyze the resonance property of the cantilever sandwich TBC blade model.