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• Quasi-periodic motions of an axially moving buckled beam have been firstly studied. • Harmonic balance method with multifrequency is used to solve quasi-periodic solutions. • Frequency resonances have been found in the quasi-periodic vibration. In this work, quasi-periodic vibration of an axially moving beam under conveying harmonic varying mass are studied. Coupled modelling equations of nonlinear vibration of an axially moving beam are established with the aid of the generalized Hamilton principle. A nonlinear partial-integro-differential equation as the transverse vibration modelling equation is deduce by decoupled method. After obtaining the equilibrium buckled state of the axially moving beam, a transverse vibration governing equation around the buckled state is presented. The Galerkin method is applied to truncate the governing equation into a set of nonlinear ordinary differential equations. The harmonic balance method with three time variables is applied to analyze quasi-periodic vibration of the nonlinear dynamic system with combined parametric and forced external excitation. Time traces and phase-plane portraits of quasi-periodic vibration are obtained, which are in excellent agreement with those of the direct time integration method. Frequency amplitude responses of the vibration are determined by the harmonic balance method with three time variables. Effects of the velocity of the axially moving beam, amplitude of the varying mass, and the external excitation frequency on the vibration amplitude of axially moving beam and the ratio of the two fundamental frequencies are investigated. [ABSTRACT FROM AUTHOR]

• Equations of a hyperelastic beam under time-varying axial loading are derived. • It falls into a barreling state with an axial load lower than the critical load. • Its transverse vibration is analyzed by Galerkin and harmonic balance methods. • The material parameter can change the behavior of its transverse vibration. Equations of motion of a hyperelastic beam under time-varying axial loading are derived via the extended Hamilton's principle in this work, where the transverse vibration is coupled with the longitudinal vibration, and nonlinear vibrations of the beam in the subcritical buckling regime are investigated. Complex nonlinear boundary conditions of the beam are determined under some geometric constraints. The critical buckling load is first determined through linear bifurcation analysis. Effects of material and geometric parameters on the forced longitudinal vibration of the beam are numerically investigated. Steady harmonic shapes of the beam at different times under harmonic axial loading are determined. The beam is in the barreling deformation state even when the axial load is not in excess of the critical buckling load. The governing equation for the nonlinear transverse vibration of the beam is obtained by decoupling its equations of motion. Natural frequencies of the free linearized transverse vibration of the beam are studied. By applying the eigenfunction expansion method, the governing equation for the nonlinear transverse vibration of the beam transforms to a series of strongly nonlinear ordinary differential equations (ODEs). Two-to-one internal resonance of the beam is studied by the numerical integration method and its phase-plane portraits are obtained. The harmonic balance method and pseudo arc-length method are used to determine steady-state periodic solutions of the beam from the strongly nonlinear ODEs, and amplitude-frequency responses of the beam are determined. Effects of the external mean axial load, excitation amplitude, and damping coefficient on the amplitude-frequency response of the beam are numerically investigated. Combined effects of the external excitation amplitude and frequency on response amplitudes are also investigated. [ABSTRACT FROM AUTHOR]

• Kinematics of axially moving beams described in Eulerian–Lagrangian formulation. • Hyperelastic beams with finite deformation and higher order shear. • Effects of material parameters on steady-state responses of vibrations. • Asymptotic equilibrium solutions in supercritical regime. In this paper, we study the vibration of an axially moving hyperelastic beam under simply supported condition. The kinematic of the axially moving beam have been described by Eulerian-Lagrangian formulation. In continuum mechanics frame, the finite deformation formula and a higher order shear deformation beam theory are applied to describe the deformation of the axially moving hyperelastic beam. In these formulas the material parameter, shear deformation and the geometric non-linearity have been taken into account. Through the Hamilton principle, the governing equations of nonlinear vibration are obtained, where the transverse vibration is coupled with the longitudinal vibration. When the velocity is a constant, the critical speed and natural frequencies are determined by solving the corresponding linear equations. Meantime, effects of the geometrical and material parameters on the critical speed and natural frequencies have been investigated. Comparisons among the critical velocities of the hyperelastic and Euler linear beam are also made. The results show that the critical velocity of hyperelastic beam is larger than that of linear Euler–Bernoulli beam. For the natural frequencies, we have the same conclusions. Lastly, by the multiple scales method, the leading order analytical solutions of the equilibrium state of axially moving hyperelastic beam in the supercritical regime are obtained. Furthermore the amplitudes of analytical solutions of the hyperelastic beam have been compared with that of linear Euler–Bernoulli beam. The effects of the material and geometrical parameters on the asymptotic solutions and the amplitude has been analyzed. [ABSTRACT FROM AUTHOR]

This paper investigates principal parametric resonance of axially accelerating hyperelastic beam. Hyperelasticity is integrated into axially moving material for the first time. Based on the continuum mechanics theory, the coupled nonlinear partial differential equations of motion are derived from the extended Hamilton’s principle. The model equations are simplified into a single integro-differential equation, which governs the transverse vibration of the hyperelastic beam. The method of multiple scales is used to solve the integro-differential equation to obtain the nonlinear response of the principal parametric resonance. The effect of the material parameter(i.e. in plane Poisson’s ratio) on the type of the nonlinear vibration behavior and amplitude of the nontrivial solutions of steady-state have been investigated. Further, the couple nonlinear governing equations are solved by Galerkin’s method. Comparison between the analytical results and the results of the Galerkin’s method are made and good agreement are found. [ABSTRACT FROM AUTHOR]

Machine vision, especially deep learning methods, has become a hot topic for product surface inspection. In practice, capturing high quality images is a base for defect detection. It turns out to be challenging for complex products as image quality suffers from occlusion, illumination, and other issues. Multiple images from different viewpoints are often required in this scenario to cover all the important areas of the products. Reducing the viewpoints while ensuring the coverage is the key to make the inspection system more efficient in production. This paper proposes a high-efficient view planning method based on deep reinforcement learning to solve this problem. First, visibility estimation method is developed so that the visible areas can be quickly identified for a given viewpoint. Then, a new reward function is designed, and the Asynchronous Advantage Actor-Critic method is applied to solve the view planning problem. The effectiveness and efficiency of the proposed method is verified with a set of experiments. The proposed method could also be potentially applied to other similar vision-based tasks. [ABSTRACT FROM AUTHOR]

We study the buckling bifurcation of a compressible hyperelastic slab under compression with sliding–sliding end conditions. The combined series-asymptotic expansions method is used to derive the simplified model equations. Linear bifurcation analysis yields the critical stress value of buckling, which gives a non-linear correction to the classical Euler buckling formula. The correction is due to the geometrical non-linearities coupled with the material non-linearities. Then through non-linear bifurcation analysis, the approximate analytical solutions for the post-buckling deformations are obtained. The amplitude of buckling is expressed explicitly in terms of the aspect ratio, the incremental dimensionless engineering stress, the mode of buckling and the material constants. Most importantly, we find that both supercritical and subcritical buckling could occur for compressible materials. The bifurcation type depends on the material constants, the geometry of the slab and the mode numbers. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we study the equilibrium states of a compressible hyperelastic layer under compression after the primary and secondary bifurcations. Starting from the two-dimensional field equations for a compressible hyperelastic material, we use a methodology of coupled series-asymptotic expansions developed earlier to derive two coupled non-linear ordinary differential equations (ODEs) as the model equations. The critical buckling stresses are determined by a linear bifurcation analysis, which are in agreement with the results in the literature. The method of multiple scales is used to solve the model equations to obtain the second-order asymptotic solutions after the primary bifurcations. An analytical formula for the post-buckling amplitudes is derived. Two kinds of numerical solutions are also obtained, the numerical solutions of the model equations by a difference method and those of the two-dimensional field equations by the finite elements method. Comparisons among the analytical solutions, numerical solutions and solutions obtained by the Lyapunov–Schmidt–Koiter (LSK) method in the literature are made and good agreements for the displacements are found. It is also found that at some places the axial strain is tensile, although the layer is under compression. To consider the secondary bifurcation, we superimpose a small deformation on the state after the primary bifurcation. With the analytical solution of the primary bifurcation, we manage to reduce the problem of the secondary bifurcation to one of the first bifurcations governed by a second order variable-coefficient ODE. And, our analysis identifies an explicit function and from the existence/non-existence of its zero one can immediately judge whether a secondary bifurcation can take place or not. The zero corresponds to a turning point of the governing ODE, which leads to non-trivial solutions. Further, by the WKB method the equation (in a very simple form) for determining the critical stress for the secondary bifurcation is derived. We further use AUTO to compute the secondary bifurcation point numerically, which confirms the validity of our analytical results. The numerical solution in the secondary bifurcation branch is also computed by AUTO. It is found that the secondary bifurcation induces a “wave number doubling” phenomenon and also the shape of the layer has a convexity change along the axial direction. [Copyright &y& Elsevier]

This paper presents a successful application of one-dimensional convolutional neural networks (1D CNNs) for waste sorting at source based on acoustic data. Most of the existing methods use images for waste classification, which causes a high computational complexity and requires a huge amount of training data. Acoustic data have also been employed due to its high correlation to the waste material type. The traditional approaches usually use fixed and handcrafted features extracted from acoustic data. Finding efficient features is usually time consuming and could be difficult in complex situations. In this paper, the 1D CNN method is proposed to automatically extract features from acoustic data and achieve high classification accuracy. Orthogonal experiment method is applied to optimize three key hyper-parameters of the 1D CNN structure. The experiment shows that the proposed method can achieve 92.40% classification accuracy within a short time. A traditional method using handcrafted features with a shallow classifier is taken as a benchmark and the attained classification accuracy is only 81.92%. In addition, a classification accuracy rate of 68.06% is achieved when using a shallow classifier with raw acoustic data as input. Therefore, the proposed method is promising to be practically applied in the trash bins for automatic waste source separation. • Proposing the 1D CNN method using acoustic data for waste sorting at source. • Dealing with complex scenarios which may occur in reality with high accuracy. • Design of orthogonal experiment for studying major hyper-parameters in 1D CNNs. • Best combination of hyper-parameters is found for highest classification accuracy. [ABSTRACT FROM AUTHOR]

• A composite catalyst rGO/NiFe-LDH modified Cu 2 O/TiO 2 heterojunction photocathode has been designed and successfully prepared. • The composite photocathode possesses great photoelectrochemical performance. The photocurrent density is −3.71 mA/cm2 at 0 V vs. RHE and the STE is 0.41%. • The influence of composite catalyst on carrier transport mechanism is discussed by analyzing the variation of the built – in electric field. Cuprous oxide is a highly efficient p-type semiconductor, which has high absorption efficiency in the visible region, making it ideal for the use as a photocathode material for hydrogen evolution reaction. However, the theoretical efficiency of cuprous oxide is still unachievable in practical situations, due to the severe photocorrosion and the high recombination rate of photogenerated electron-hole pairs. In this work, ultra-thin TiO 2 deposited via atomic layer deposition (ALD) was used as a protection layer, and rGO/NiFe-LDH was loaded as a catalyst decoration on Cu 2 O photocathode. The protection layer led to suppression of photocorrosion of Cu 2 O, and the catalyst promoted chemical reaction kinetics. The photo-generated current density reached −3.71 mA/cm2, and the photoelectric conversion efficiency reached 0.41%. The effect of catalyst on the built-in electric field of photocathode and the transport mechanism of carrier were also investigated in detail. This work hereby provides a new idea of the application of Cu 2 O in the domain of photoelectrochemical (PEC) water splitting. [ABSTRACT FROM AUTHOR]

Automated surface inspection has become a hot topic with the rapid development of machine vision technologies. Traditional machine vision methods need experts to carefully craft image features for defect detection. This limits their applications to wider areas. The emerging convolutional neural networks (CNN) can automatically extract features and yield good results in many cases. However, the CNN-based image classification methods are more suitable for flat surface texture inspection. It is difficult to accurately locate small defects in geometrically complex products. Furthermore, the computational power required in CNN algorithms is usually high and it is not efficient to be implemented on embedded hardware. To solve these problems, a smart surface inspection system is proposed using faster R-CNN algorithm in the cloud-edge computing environment. The faster R-CNN as a CNN-based object detection method can efficiently identify defects in complex product images and the cloud-edge computing framework can provide fast computation speed and evolving algorithm models. A real industrial case study is presented to illustrate the effectiveness of the proposed method. The results show that the proposed method can provide high detection accuracy within a short time. [ABSTRACT FROM AUTHOR]

The electrochemical splitting of water is considered to be an efficient and potential technique for producing clean hydrogen and oxygen. Although, there are lots of significant developments in composite of superior hydrogen evolution reaction (HER) or oxygen evolution reaction (OER) catalyst applied in water splitting currently, designing non-precious and low-cost bifunctional electrocatalysts with high performance is still an attractive challenging issue. In this article, we report a novel bifunctional electrocatalyst with cobalt-based nanoparticles (NPs) embedded in Zn-doped hierarchical porous three-dimension N-doped carbonization structure via an annealing process of metal organic frameworks (MOFs) connected by N-doped carbon nanotube (denoted as Co–Zn/PNC). This composite structure possesses the characteristics of more active sites, numerous mesopores and high conductivity. The resulting electrocatalyst (Co–Zn/PNC) can be used as both anode and cathode to roust the overall water splitting, getting a current density of 10 mA cm−2 at a cell voltage of 1.63 V in 1.0 M KOH electrolyte. • Co–Zn/PNC is prepared by Zn-doped ZIF-67 linked by N-doped CNT through pyrolysis. • Bifunctional electrocatalyst Co–Zn/PNC exhibits excellent HER and OER performance. • Zn doping can enhance the electrochemical performance of Co–Zn/PNC. [ABSTRACT FROM AUTHOR]

Abstract: Multiferroic BiFeO3 (bismuth ferrite, BFO) ceramics were sintered using a rapid heating and quenching technique in an atmosphere of argon or oxygen. The resulting ceramics were phase pure with the space group R3c. BFO ceramics sintered under an argon atmosphere contained more oxygen vacancies and Fe2+ ions compared with those sintered under an oxygen atmosphere, which resulted in high dielectric loss and large dielectric dispersion. It confirms that the unavoidable Fe2+ ions may play a fundamental role in these special materials, such as in the evaporation of the Bi component and valence change of the Fe component. This work also discusses the dielectric response mechanism in BFO ceramics. [Copyright &y& Elsevier]

Abstract: A chemical co-precipitation method is proposed for the synthesis of nano-sized multiferroic BiFeO3 powders. Pure phase can be obtained by controlling the chemical co-precipitation process, pH level, Bi content, and calcination temperature. The evolutions of phase constitution and structural characteristic of BiFeO3 powders were investigated by XRD, FT-IR, SEM, and TEM techniques. The slight excess in Bi content plays an important role in the synthesis. The resultant BiFeO3 powders are of pure phase and have the R3c crystal structure under optimized conditions. The grain size of the BiFeO3 powders with weak magnetism ranges from 30–40nm. [ABSTRACT FROM AUTHOR]

Abstract: Alkali-treatment was performed to modify the surface of the TiO2-based film containing Ca and P prepared by microarc oxidation (MAO) technique for improving the apatite-forming ability of the MAO film. Before alkali-treatment, in the MAO film amorphous and crystalline regions with main composition of Ti, Ca, P and Al both were observed; and in the latter TiO2 nanocrystals were randomly distributed in Ca- and P-doped matrix. After alkali-treatment, the surfaces of the MAO films become rough, and the Ca and P concentrations decrease with increasing the concentration of NaOH solution (1, 3 and 5 mol/L). When 5 mol/L NaOH solution was used, amorphous calcium titanate hydrogel was formed on the surface, showing a nanoflake-like morphology. In vitro experiment indicates that the ability to induce apatite formation of the alkali-treated MAO films increase with increasing the concentration of NaOH solution, which is associated with the formation of Ti–OH groups during the incubation process in a simulated body fluid. [Copyright &y& Elsevier]