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A quasi-zero stiffness energy harvesting isolator with triple negative stiffness

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Acta Mechanica Sinica 2024年第8期40卷 219-238页

作者： Xiangyu Cai Tao Yang Weiyang Qin Zhongliang Xie research&development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen518057China Department of Engineering Mechanics Northwestern Polytechnical UniversityXi’an710072China

Vibration isolation for low frequency excitation and the power supply for low power monitoring sensors are important issues in bridge *** main problem is how to effectively combine the vibration isolator with the energy harvester to form a multi-functional *** this paper,a system called quasi-zero stiffness energy harvesting isolator(QZS-EHI)with triple negative stiffness(TNS)is *** TNS structure consists of linear springs,rigid links,sliders,and ring permanent ***’s second law and Kirchhoff’s law construct dynamic equations of the QZS-EHI,and a comparison is made to contrast it with other QZS and linear *** comparison field includes the QZS range,amplitude-frequency relationship,force transmissibility,and energy harvested *** isolator can be applied to many engineering fields such as bridges,automobiles,and railway *** paper selects bridge engineering as the main field for the dynamic analysis of this *** the multi-span beam bridge,this paper compares different situations including the bridge with QZS-EHI support,with linear stiffness isolator support,and with single beam *** results show that the QZS-EHI is not only better than the traditional isolator with linear stiffness under both harmonic and stochastic excitation,but also better than some QZS isolators with double or single negative stiffness in bridge vibration isolation and energy *** analysis is verified to correspond to the simulation analysis,which means the proposed QZS-EHI has practical application value.

关键词： Quasi-zero stiffness Triple negative stiffness Vibration isolation Energy harvesting

Secure Tracking Control via Fixed-Time Convergent Reinforcement Learning for a UAV CPS

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1699-1701页

作者： Zhenyu Gong Feisheng Yang the School of Automation Northwestern Polytechnical UniversityXi’an 710129 the research&development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China

Dear Editor,This letter is concerned with the secure tracking control problem in the unmanned aerial vehicle(UAV) system by fixed-time convergent reinforcement learning(RL). By virtue of the zero-sum game,the false da... 详细信息

关键词： Secure Fixed false

Modeling analysis of cobalt-based Fischer-Tropsch catalyst particles

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Chinese Journal of Chemical Engineering 2024年第6期70卷 82-92页

作者： Huashuai Wu Gang Wang Yong Yang Yongwang Li College of Chemical Engineering and Technology Taiyuan University of TechnologyTaiyuan 030024China National Energy research&development Center for Coal to Liquid Fuels Synfuels China CompanyLimitedBeijing 101400China

The influences of particle size,shape,and catalyst distribution on the reactivity and hydrocarbon product selectivity of a cobalt-based catalyst for Fischer-Tropsch synthesis were investigated in the present work.A self-consistent kinetic model for Fischer-Tropsch reaction proposed here was found to correlate experimental data well and hence was used to describe the consumption rates of reactants and formation rates of hydrocarbon *** perturbed-chain statistical associating fluid theory equation of state was used to describe vapor-liquid equilibrium behavior associated with Fischer-Tropsch *** interaction between intraparticle diffusion and Fischer-Tropsch reaction was investigated in *** showed that in order to avoid the adverse influence of intraparticle diffusional limitations on catalyst reactivity and product selectivity,the use of small particles is *** eggshell spherical particles are shown to keep the original catalyst reactivity and enhance the selectivity of heavy hydrocarbon *** suitable layer thickness for a spherical particle with a diameter of 2 mm is nearly 0.15 *** the same outer diameter of 2 mm,the catalyst reactivity and heavy product selectivity of hollow cylindrical particles with a layer thickness of 0.25 mm are found to be larger than eggshell spherical *** the viewpoint of catalytic performance,hollow cylindrical particles are a better choice for industrial applications.

关键词： Fischer-Tropsch synthesis Kinetic modeling Vapor-liquid equilibria Numerical simulation Intraparticle diffusion Particle shapes

Phenylhydrazone anions excitation for the photochemical carbonylation of aryl iodides with aldehydes

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Chinese Chemical Letters 2024年第4期35卷 346-351页

作者： Lei Shen Yang Zhang Linlin Zhang Chuanwang Liu Zhixian Ma Kangjiang Liang Chengfeng Xia Key Laboratory of Medicinal Chemistry for Natural Resource Ministry of EducationYunnan Provincial Center for Research&Development of Natural ProductsSchool of PharmacyYunnan UniversityKunming 650500China

Spectroscopic investigations discovered that the in-situ generated phenylhydrazone anion was significantly bathochromically shifted to visible light region for photoactivation under irradiation. The photoexcited phenylhydrazone anion was potential to reduce aryl iodides via single electron transfer process for the subsequent radical chain reaction. A redox-neutral photochemical carbonylation of aryl iodides was developed on basis of the special spectroscopic features of phenylhydrazone anion. This protocol provided a convenient and efficient synthetic tool for accessing carbonylation products under redox neutral conditions without the need of transition-metals.

关键词： Organic anion Hydrazone Carbonylation Visible light Single electron transfer

Geometric Constraints for Global Regularity of 3D Shear Thickening Fluids

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 205-210页

作者： Jia-qi Yang research&development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen518063China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China

We consider the relation between the direction of the vorticity and the global regularity of 3D shear thickening *** is showed that a weak solution to the non-Newtonian incompressible fluid in the whole space is stron... 详细信息

关键词： direction of the vorticity non-Newtonian fluid global regularity

Protective Effects of Danmu Extract Syrup on Acute Lung Injury Induced by Lipopolysaccharide in Mice through Endothelial Barrier Repair

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Chinese Journal of Integrative Medicine 2024年第3期30卷 243-250页

作者： XU Han XU Si-cong LI Li-yan WU Yu-huang TAN Yin-feng CHEN Long LIU Pei LIANG Chang-fu HE Xiao-ning LI Yong-hui Hainan Provincial Key Lab of research&development on Tropic Herbs Hainan Medical UniversityHaikou571199China Department of Stomatology the Second Affiliated Hospital of Hainan Medical UniversityHaikou571199China

Objective:To investigate the effects of Danmu Extract Syrup(DMS) on lipopolysaccharide(LPS)-induced acute lung injury(ALI) in mice and explore the ***:Seventy-two male Balb/C mice were randomly divided into 6 groups according to a random number table(n=12),including control(normal saline),LPS(5 mg/kg),LPS+DMS 2.5 mL/kg,LPS+DMS 5 mL/kg,LPS+DMS 10 mL/kg,and LPS+Dexamethasone(DXM,5 mg/kg) *** pretreatment with DMS and DXM,the ALI mice model was induced by LPS,and the bronchoalveolar lavage fluid(BALF) were collected to determine protein concentration,cell counts and inflammatory *** lung tissues of mice were stained with hematoxylin-eosin,and the wet/dry weight ratio(W/D) of lung tissue was *** levels of tumor necrosis factor-α(TNF-α),interleukin(IL)-6 and IL-1βin BALF of mice were detected by enzyme linked immunosorbent *** expression levels of Claudin-5,vascular endothelial(VE)-cadherin,vascular endothelial growth factor(VEGF),phospho-protein kinase B(p-Akt) and Akt were detected by Western blot ***:DMS pre-treatment significantly ameliorated lung histopathological *** with the LPS group,the W/D ratio and protein contents in BALF were obviously reduced after DMS pretreatment(P<0.05 or P<0.01).The number of cells in BALF and myeloperoxidase(MPO) activity decreased significantly after DMS pretreatment(P<0.05 or P<0.01).DMS pre-treatment decreased the levels of TNF-α,IL-6 and IL-1β(P<0.01).Meanwhile,DMS activated the phosphoinositide 3-kinase/protein kinase B(PI3K/Akt) pathway and reversed the expressions of Claudin-5,VE-cadherin and VEGF(P<0.01).Conclusions:DMS attenuated LPS-induced ALI in mice through repairing endothelial *** might be a potential therapeutic drug for LPS-induced lung injury.

关键词： Danmu Extract Syrup acute lung injury inflammatory factors vascular endothelial growth factor phosphoinositide 3-kinase/protein kinase B Chinese medicine Nauclea officinalis

Resonance mechanism of flapping wing based on fluid structure interaction simulation

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Chinese Journal of Aeronautics 2024年第5期37卷 243-262页

作者： Yueyang GUO Wenqing YANG Yuanbo DONG Dong XUE National Key Laboratory of Science and Technology on Aerodynamic Design and research School of AeronauticsNorthwestern Polytechnical UniversityXi'an 710072China research&development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China Yangtze River Delta research Institute of Northwestern Polytechnical University Taicang 215400China

Certain insect species have been observed to exploit the resonance mechanism of their *** order to achieve resonance and optimize aerodynamic performance,the conventional approach is to set the flapping frequency of flexible wings based on the Traditional Structural Modal(TSM)***,there exists controversy among researchers regarding the relationship between frequency and aerodynamic *** that the structural response of wings can be influenced by the surrounding air vibrations,an analysis known as Acoustic Structure Interaction Modal(ASIM)is introduced to calculate the resonant *** this study,Fluid Structure Interaction(FSI)simulations are employed to investigate the aerodynamic performance of flapping wings at modal frequencies derived from both TSM and ASIM *** performance is evaluated for various mass ratios and frequency ratios,and the findings indicate that the deformation and changes in vortex structure exhibit similarities at mass ratios that yield the highest aerodynamic ***,the flapping frequency associated with the maximum time-averaged vertical force coefficient at each mass ratio closely aligns with the ASIM frequency,as does the frequency corresponding to maximum ***,the ASIM analysis can provide an effective means for predicting the optimal flapping frequency for flexible ***,it enables the prediction that flexible wings with varying mass ratios will exhibit similar deformation and vortex structure *** paper offers a fresh perspective on the ongoing debate concerning the resonance mechanism of Flexible Flapping Wings(FFWs)and proposes an effective methodology for predicting their aerodynamic performance.

关键词： Flexible Flapping Wing(FFW) Acoustic Structure Interaction Modal(ASIM) Fluid Structure Interaction(FSI) Resonance mechanism Aerodynamic performance

Effects of dynamical spanwise retraction and stretch on flapping-wing forward flights

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Chinese Journal of Aeronautics 2024年第4期37卷 181-202页

作者： Kang LIU Bifeng SONG Ang CHEN Zhihe WANG Dong XUE Wenqing YANG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Intelligent Aircraft research Center Chengdu Technological UniversityChengdu 610031China research&development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China Harbin Institute of Technology Shenzhen 518055China

Birds and bats retract and stretch their wings dynamically during each flap in level flights, implying intriguing mechanisms for the aerodynamic performance improvement of flapping wings. A numerical investigation into the aerodynamic effects of such bio-inspired concept in forward flights has been performed based on a three-dimensional wing in plunging motion and a twosection wing in flapping motion. The currently considered Reynolds number and Strouhal number are Re=1.5×10^(5) and St=0.3, respectively. During the research, the mean angle of attack is varied in relatively wide ranges to achieve lift-thrust interconversion for the wings. The conclusive results show that dynamical spanwise retraction and stretch has induced three absolutely desirable scenarios for the oscillating wings in forward flights, namely producing more lift and consuming less power for a given thrust generation, producing more thrust and consuming less power for a given lift generation, and producing more lift and more thrust while consuming less power. Furthermore,the morphing wings have alleviated periodical aerodynamic load fluctuations compared with the non-morphing baseline. The mechanism of the aerodynamic effects of the bionic morphing mode is analyzed with the aid of field visualization. The current article is the first to reveal the absolute advantages of the bionic spanwise morphing. Hopefully, it may help comprehend the behaviors of natural fliers and provide inspirations for performance enhancement of micro artificial flappingwing vehicles.

关键词： Flapping wing Morphing wing Bionic Aerodynamics Vortex Flight

An Enhanced GAN for Image Generation

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Computers, Materials & Continua 2024年第7期80卷 105-118页

作者： Chunwei Tian Haoyang Gao Pengwei Wang Bob Zhang PAMI research Group University of MacaoMacao999078China School of Software Northwestern Polytechnical UniversityXi’an710129China Yangtze River Delta research Institute Northwestern Polytechnical UniversityTaicang215400China research&development Institute Northwestern Polytechnical UniversityShenzhen518057China

Generative adversarial networks(GANs)with gaming abilities have been widely applied in image ***,gamistic generators and discriminators may reduce the robustness of the obtained GANs in image generation under varying *** the relation of hierarchical information in a generation network and enlarging differences of different network architectures can facilitate more structural information to improve the generation effect for image *** this paper,we propose an enhanced GAN via improving a generator for image generation(EIGGAN).EIGGAN applies a spatial attention to a generator to extract salient information to enhance the truthfulness of the generated *** into relation the context account,parallel residual operations are fused into a generation network to extract more structural information from the different ***,a mixed loss function in a GAN is exploited to make a tradeoff between speed and accuracy to generate more realistic *** results show that the proposed method is superior to popular methods,i.e.,Wasserstein GAN with gradient penalty(WGAN-GP)in terms of many indexes,i.e.,Frechet Inception Distance,Learned Perceptual Image Patch Similarity,Multi-Scale Structural Similarity Index Measure,Kernel Inception Distance,Number of Statistically-Different Bins,Inception Score and some visual images for image generation.

关键词： Generative adversarial networks spatial attention mixed loss image generation