In this paper, the nonlinear free vibration behaviors of the piezoelectric semiconductor(PS) doubly-curved shell resting on the Pasternak foundation are studied within the framework of the nonlinear drift-diffusion(NL...
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In this paper, the nonlinear free vibration behaviors of the piezoelectric semiconductor(PS) doubly-curved shell resting on the Pasternak foundation are studied within the framework of the nonlinear drift-diffusion(NLDD) model and the first-order shear deformation theory. The nonlinear constitutive relations are presented, and the strain energy, kinetic energy, and virtual work of the PS doubly-curved shell are *** on Hamilton's principle as well as the condition of charge continuity, the nonlinear governing equations are achieved, and then these equations are solved by means of an efficient iteration method. Several numerical examples are given to show the effect of the nonlinear drift current, elastic foundation parameters as well as geometric parameters on the nonlinear vibration frequency, and the damping characteristic of the PS doublycurved shell. The main innovations of the manuscript are that the difference between the linearized drift-diffusion(LDD) model and the NLDD model is revealed, and an effective method is proposed to select a proper initial electron concentration for the LDD model.
In many engineering applications,it is essential to have information about rocks that inherently contain preexisting flaws under dynamic loading *** impact tests are conducted on samples with varying flaw angles using...
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In many engineering applications,it is essential to have information about rocks that inherently contain preexisting flaws under dynamic loading *** impact tests are conducted on samples with varying flaw angles using the split Hopkinson pressure bar(SHPB)test system and the Digital Image Correlation system(DIC).The characteristics of the samples after dynamic loading,including dynamic strength,energy dissipation,and fractal fracture,are compared and *** the flaw angle increases,the peak stress and strain exhibit a typical V-shaped pattern,reaching the minimum value at 30,and the initial initiation position shifts from the flaw tips to the middle of the *** modes can be divided into three modes depending on the flaw *** progressive failure process,taking into account the heterogeneity of the rock,is demonstrated by developing an elastic damage constitutive model that uses dynamic compression and tensile tests to parameterize *** the flaw angle increases,the initial damage zone also moves from the flaw tips to the middle of the *** around the hole with redistributed stress are observed,and the failure mechanisms can be explained with the aid of strain energy density(SED).Using fracture mechanics,the analytical solution of stress around the flaw is provided,and the variation of crack initiation angle,stress distribution,and energy dissipation under different flaw angles is theoretically explained,which is in good agreement with the experimental and simulated results.
Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway *** present,wheel/rail medium-or hig...
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Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway *** present,wheel/rail medium-or high-frequency frictional interactions are perceived as an essential reason of the high-order polygonal wear of railway wheels,which are potentially resulted by the flexible deformations of the train/track system or other external *** this work,the effect of wheel/rail flexibility on polygonal wear evolution of heavy-haul locomotive wheels is explored with aid of the long-term wheel polygonal wear evolution simulations,in which different flexible modeling of the heavy-haul wheel/rail coupled system is ***,the mitigation measures for the polygonal wear of heavy-haul locomotive wheels are *** results point out that the evolution of polygonal wear of heavy-haul locomotive wheels can be veritably simulated with consideration of the flexible effect of both wheelset and *** of mixed-line operation of heavy-haul trains and application of multicut wheel re-profiling can effectively reduce the development of wheel polygonal *** research can provide a deep-going understanding of polygonal wear evolution mechanism of heavy-haul locomotive wheels and its mitigation measures.
This paper presents an integrated control scheme for enhancing the ride comfort and handling performance of a four-wheel-independent-drive electric vehicle through the coordination of active suspension system(ASS)and ...
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This paper presents an integrated control scheme for enhancing the ride comfort and handling performance of a four-wheel-independent-drive electric vehicle through the coordination of active suspension system(ASS)and anti-lock braking system(ABS).First,a longitudinal-vertical coupled vehicle dynamics model is established by integrating a road input *** the coupling mechanisms between longitudinal and vertical vehicle dynamics are *** ASS-ABS integrated control system is proposed,utilizing an H∞controller for ASS to optimize load transfer effect and a neural network sliding mode control for ABS ***,the effectiveness of the proposed control scheme is evaluated through comprehensive tests conducted on a hardware-in-loop(HIL)test *** HIL test results demonstrate that the proposed control scheme can significantly improve the braking performance and ride comfort compared to conventional ABS control methods.
Aiming at the serious problem of wheel wear of six-axle heavy haul locomotive, the wheel-rail interface friction theory is introduced to study the influence of different friction coefficients on wheel wear. The heavy ...
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The dynamic vibration absorber with inerter and grounded stiffness(IGDVA)is used to control a two-scale system subject to a weak periodic *** vibration suppression effect is *** amplitude of the main system coupled wi...
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The dynamic vibration absorber with inerter and grounded stiffness(IGDVA)is used to control a two-scale system subject to a weak periodic *** vibration suppression effect is *** amplitude of the main system coupled with absorber is significantly reduced,and the high frequency vibration completely ***,through the slow-fast analysis and stability theory,it is found that the stability of the autonomous system exerts a notable regulating effect on the vibration response of the non-autonomous *** adding the dynamic vibrator absorber,the center in the autonomous system changes to an asymptotically stable focus,consequently suppressing the vibration in the non-autonomous *** research reveals that the parameters of the absorber affect the real parts of the eigenvalues of the autonomous system,thereby regulating the stability of the *** from a qualitative standpoint to a quantitative approach,a comparison of the solutions before and after the introduction of the dynamic absorber reveals that,when the grounded stiffness ratio and the mass ratio of the dynamic absorber are not equal,the high-frequency part in the analytical solution *** a result,this leads to a reduction in the amplitude of the trajectory,achieving a vibration reduction effect.
In order to study the evolution law of wheel profile wear of heavy-haul freight wagon and the influence of worn wheel profile on wheel-rail contact relationship, taking C80 heavy-haul freight wagon as the research obj...
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A sub-domain transfer learning method based on multi-scale convolutional neural network and infrared thermal images is proposed to improve the diagnostic accuracy of bearing faults. Firstly, infrared thermal images wi...
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The theory of compressed sensing is introduced to solve the repairing of missing data collected in PHM monitoring. An improved measurement matrix is proposed to optimize the conventional measurement matrix to increase...
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Air conditioning water systems account for a large proportion of building energy *** a pressure-controlled water system,one of the key measures to save energy is to adjust the differential pressure setpoints during **...
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Air conditioning water systems account for a large proportion of building energy *** a pressure-controlled water system,one of the key measures to save energy is to adjust the differential pressure setpoints during ***,such adjustments are based either on certain rules,which rely on operator experience,or on complicated models that are not easy to *** this paper,a data-driven control method based on reinforcement learning is *** main idea is to construct an agent model that adapts to the researched *** of directly being told how to react,the agent must rely on its own experiences to *** with traditional control strategies,reinforcement learning control(RLC)exhibits more accurate and steady performances while maintaining indoor air temperature within a limited range.A case study shows that the RLC strategy is able to save substantial amounts of energy.
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