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Bandgap adjustment of a sandwich-like acoustic metamaterial plate with a frequency-displacement feedback control method

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Applied Mathematics and Mechanics(English Edition) 2024年第10期45卷 1807-1820页

作者： Jianing LIU Jinqiang LI Ying WU school of Aerospace engineering Xi'an Jiaotong University College of Aerospace and civil engineering Harbin Engineering University

Several types of acoustic metamaterials composed of resonant units have been developed to achieve low-frequency bandgaps. In most of these structures, bandgaps are determined by their geometric configurations and material properties. This paper presents a frequency-displacement feedback control method for vibration suppression in a sandwich-like acoustic metamaterial plate. The band structure is theoretically derived using the Hamilton principle and validated by comparing the theoretical calculation results with the finite element simulation results. In this method, the feedback voltage is related to the displacement of a resonator and the excitation frequency. By applying a feedback voltage on the piezoelectric fiber-reinforced composite(PFRC) layers attached to a cantilever-mass resonator, the natural frequency of the resonator can be adjusted. It ensures that the bandgap moves in a frequency-dependent manner to keep the excitation frequency within the bandgap. Based on this frequency-displacement feedback control strategy, the bandgap of the metamaterial plate can be effectively adjusted, and the vibration of the metamaterial plate can be significantly suppressed.

关键词： 35B34 74H45 acoustic metamaterial electromechanical coupling Hamilton principle local resonance O328 vibration control

A sponge-based iron-tannic-acid hydrogel interface evaporator designed for clean water production

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Science China(Technological Sciences) 2024年第5期67卷 1579-1591页

作者： ZHANG ZeKun LI ChengLong TAO HuaYu GE Bo ZHANG YongLe ZHAO LiMin LIU JunChang REN GuiNa ZHANG ZhaoZhu school of Materials Science and engineering Liaocheng UniversityLiaocheng252059China school of Environmental and Material engineering Yantai UniversityYantai264405China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China

Due to the rapid advancement of technologies,there has been a significant increase in the discharge of industrial wastewater,and freshwater is becoming a scarce ***,research on solar evaporators is mainly focused on the efficient production of clean water,with less emphasis on the removal of residual pollutants remaining in the original *** this study,problems,including the difficult recovery of catalyst powder and the difficult removal of floating organic matter are solved by co-depositing low-surface-tension zirconia particles and bismuth tungstate onto the floating *** and melamine sponges were combined to solve the problem that traditional hydrogels lack mechanical *** excellent water-repellent effect can be seen from the contact angle between the liquid globule and canvas/felt,which is greater than 155°.The steam generation rate of the assembled evaporation system is 1.78 kg m^(-2)h^(-1),and its purification efficiency for methyl orange and rhodamine B exceeds 99%.This study presents a novel strategy for treating wastewater contaminated with organic dyes,aiming to solve problems including environmental damage,water pollution,and water scarcity.

关键词： oil removal non-wetting interface

Prediction model for corrosion rate of low-alloy steels under atmospheric conditions using machine learning algorithms

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 337-350页

作者： Jingou Kuang Zhilin Long school of civil engineering Xiangtan UniversityXiangtan 411105China

This work constructed a machine learning(ML)model to predict the atmospheric corrosion rate of low-alloy steels(LAS).The material properties of LAS,environmental factors,and exposure time were used as the input,while the corrosion rate as the output.6 dif-ferent ML algorithms were used to construct the proposed *** optimization and filtering,the eXtreme gradient boosting(XG-Boost)model exhibited good corrosion rate prediction *** features of material properties were then transformed into atomic and physical features using the proposed property transformation approach,and the dominant descriptors that affected the corrosion rate were filtered using the recursive feature elimination(RFE)as well as XGBoost *** established ML models exhibited better predic-tion performance and generalization ability via property transformation *** addition,the SHapley additive exPlanations(SHAP)method was applied to analyze the relationship between the descriptors and corrosion *** results showed that the property transformation model could effectively help with analyzing the corrosion behavior,thereby significantly improving the generalization ability of corrosion rate prediction models.

关键词： machine learning low-alloy steel atmospheric corrosion prediction corrosion rate feature fusion

In situ formation of multiple catalysts for enhancing the hydrogen storage of MgH_(2) by adding porous Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres

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Journal of Magnesium and Alloys 2024年第3期12卷 1227-1238页

作者： Bing Zhang Xiubo Xie Yukun Wang Chuanxin Hou Xueqin Sun Yuping Zhang Xiaoyang Yang Ronghai Yu Wei Du school of Environmental and Material engineering Yantai UniversityNo.30 Qingquan RoadYantai 264005China Key Laboratory of Aerospace Materials and Performance(Ministry of Education)school of Materials Science and engineering Beihang UniversityNo.37 Xueyuan RoadBeijing 100191China

MgH_(2) is considered one of the most promising hydrogen storage materials because of its safety,high efficiency,high hydrogen storage quantity and low cost *** some shortcomings are still existed:high operating temperature and poor hydrogen absorption dynamics,which limit its *** Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres(NZC/Ni@CNT)is prepared by facile filtration and calcination *** the different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%)is added to the MgH_(2) by ball *** the three samples with different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%),the MgH_(2)-5 wt%NZC/Ni@CNT composite exhibits the best hydrogen storage *** testing,the MgH_(2)-5 wt%NZC/Ni@CNT begins to release hydrogen at around 110℃ and hydrogen absorption capacity reaches 2.34 wt%H_(2) at 80℃ within 60 ***,the composite can release about 5.36 wt%H_(2) at 300℃.In addition,hydrogen absorption and desorption activation energies of the MgH_(2)-5 wt%NZC/Ni@CNT composite are reduced to 37.28 and 84.22 KJ/mol H_(2),*** in situ generated Mg_(2)NiH_(4)/Mg_(2)Ni can serve as a"hydrogen pump"that plays the main role in providing more activation sites and hydrogen diffusion channels which promotes H_(2) dissociation during hydrogen absorption *** addition,the evenly dispersed Zn and MgZn2 in Mg and MgH_(2) could provide sites for Mg/MgH_(2) nucleation and hydrogen diffusion *** attempt clearly proved that the bimetallic carbide Ni_(3)ZnC_(0.7) is a effective additive for the hydrogen storage performances modification of MgH_(2),and the facile synthesis of the Ni_(3)ZnC_(0.7)/Ni@CNT can provide directions of better designing high performance carbide catalysts for improving MgH_(2).

关键词： Mg-based hydrogen storage material Ni_(3)ZnC_(0.7)/Ni@CNT particles Ni loaded carbon nanotubes Multiple catalysts.

New Insight into the Flexoelectricity in the View of Mechanics of Materials:Prismatic Beams Subjected to Bending

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Acta Mechanica Solida Sinica 2024年第4期37卷 555-569页

作者： Xu Yang Lingling Chen Shengyou Yang Department of engineering Mechanics School of Civil EngineeringShandong UniversityJinan250061China

Flexoelectricity is a fascinating electromechanical phenomenon that occurs in non-homogeneously deformed dielectric *** piezoelectricity,the flexoelectric effect is highly dependent on both the material scale and the deformation *** several theoretical models have been proposed to explain the mechanism of flexoelectricity,these models can be rather complicated for those who are interested in studying the *** paper aims to simplify the understanding of flexoelectricity by focusing on the bending behavior of a prismatic dielectric beam from a mechanics of material *** avoid using complicated mathematical formulations based on continuum mechanics,including advanced tensor algebra and calculus of *** formulation clearly explains how inhomogeneous deformations and material size affect the electromechanical coupling,changing the effective bending stiffness,deflection,and rotation angles of a bending *** hope this paper can help undergraduate students and researchers,who are unfamiliar with the electromechanical coupling in flexoelectricity,to develop an understanding of this phenomenon and encourage further research in this area.

关键词： bending formulation dielectric

Research on the Method of Heat Preservation and Heating for the Drilling System of Polar Offshore Drilling Platform

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Energy engineering 2024年第5期121卷 1173-1193页

作者： Yingkai Dong Chaohe Chen Guangyan Jia Lidai Wang Jian Bai Oil and Gas Research and Development Center CIMC RAFFLESYantai264000China school of civil engineering and Transportation South China University of TechnologyGuangzhou510641China yantai Hangxiao Steel Structure Assembly Construction Co. Ltd.Yantai264000China

This study investigates the heat dissipation mechanism of the insulation layer and other plane insulation layers in the polar drilling rig *** the basic theory of heat transfer with the environmental requirements of polar drilling operations and the characteristics of polar drilling processes,we analyze the factors that affect the insulation effect of the drilling rig *** factors include the thermal conductivity of the insulation material,the thickness of the insulation layer,ambient temperature,and wind *** optimize the thermal insulation material of the polar drilling rig system using a steady-state method to measure solid thermal *** analyzing the distribution of temperature in space after heating,we optimize the distribution and air outlet angle of the heater using Fluent hydrodynamics *** results demonstrate that under polar conditions,polyisocyanurate with stable thermodynamic properties is selected as the thermal insulation *** selection of thermal insulation material and thickness significantly affects the thermal insulation effect of the system but has little effect on its heating ***,when the air outlet angle of the heater is set to 32.5°,the heating efficiency of the system can be effectively *** to heat transfer equations and heat balance theory,we determine that the heating power required for the system to reach 5°C is close to numerical simulation.

关键词： Polar drilling drilling system fluid dynamics heat preservation and heating numerical simulation

Analytical Solutions for an Isotropic Elastic Half-Plane with Complete Surface Effects Subjected to a Concentrated/Uniform Surface Load

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Acta Mechanica Solida Sinica 2024年第3期37卷 371-384页

作者： Xia-Hui Pan school of civil engineering Henan Polytechnic UniversityJiaozuo454003China

Within the context of Gurtin-Murdoch surface elasticity theory,closed-form analytical solutions are derived for an isotropic elastic half-plane subjected to a concentrated/uniform surface *** the effects of residual surface stress and surface elasticity are *** stress function method and Fourier integral transform technique are *** solutions are provided in a compact manner that can easily reduce to special situations that take into account either one surface effect or none at *** results indicate that surface effects generally lower the stress levels and smooth the deformation profiles in the *** elasticity plays a dominant role in the in-plane elastic fields for a tangentially loaded half-plane,while the effect of residual surface stress is fundamentally crucial for the out-of-plane stress and displacement when the half-plane is normally *** the remaining situations,combined effects of surface elasticity and residual surface stress should be *** results for a concentrated surface force serve essentially as fundamental solutions of the Flamant and the half-plane Cerruti problems with surface *** solutions presented in this work may be helpful for understanding the contact behaviors between solids at the nanoscale.

关键词： Surface effects Residual surface stress Surface elasticity Half-plane Analytical solutions

Surface Elastic Effects on Electromechanical Responses of a Piezoelectric Semiconducting Nanobeam

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Acta Mechanica Solida Sinica 2024年第4期37卷 598-612页

作者： Aowen Bao Xiaobao Li Yuxue Pu Chunxiao Zhan school of civil engineering Hefei University of TechnologyHefei230009China

Piezoelectric semiconductors(PSCs)find extensive applications in modern smart electronic devices because of their dual properties of being piezoelectric and *** the increasing demand for miniaturization of these devices,the performance of their components needs to be carefully designed and optimized,especially when reduced to *** has been shown that surface elastic properties play a substantial role in the mechanical performance of nanoscale materials and *** on this understanding,the surface elastic effects,encompassing surface residual stress,surface membrane stiffness,and surface bending stiffness,are comprehensively taken into account to explore the electromechanical responses of a PSC ***,the flexoelectric effect on their responses is also systematically *** results of this work reveal that surface elastic properties predominantly influence mechanical performance,while the flexoelectric effect plays a more dominant role in electric-related quantities at the ***,the significance of surface bending rigidity,which was often underestimated in the earlier literature,is ***,owing to the flexoelectric effect,the linear distribution of electric potential and charge carriers along the length transforms into a nonlinear *** distributions of electric potential and charge carriers across the cross section are also evidently ***,the size-dependent responses are *** findings may provide valuable insights for optimizing electronic devices based on nanoscale PSCs.

关键词： Surface elastic effect Flexoelectricity Size effect Piezoelectric semiconductor

Stability analysis of a liquid crystal elastomer self-oscillator under a linear temperature field

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 337-354页

作者： Haiyang WU Jiangfeng LOU Biao ZHANG Yuntong DAI Kai LI school of civil engineering Anhui Jianzhu UniversityHefei 230601China

Self-oscillating systems abound in the natural world and offer substantial potential for applications in controllers,micro-motors,medical equipments,and so ***,numerical methods have been widely utilized for obtaining the characteristics of self-oscillation including amplitude and ***,numerical methods are burdened by intricate computations and limited precision,hindering comprehensive investigations into self-oscillating *** this paper,the stability of a liquid crystal elastomer fiber self-oscillating system under a linear temperature field is studied,and analytical solutions for the amplitude and frequency are ***,we establish the governing equations of self-oscillation,elucidate two motion regimes,and reveal the underlying ***,we conduct a stability analysis and employ a multi-scale method to obtain the analytical solutions for the amplitude and *** results show agreement between the multi-scale and numerical *** research contributes to the examination of diverse self-oscillating systems and advances the theoretical analysis of self-oscillating systems rooted in active materials.

关键词： self-oscillation stability analysis multi-scale method liquid crystal elastomer linear temperature field