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A low-frequency pure metal metamaterial absorber with continuously tunable stiffness

Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1209-1224页

作者： xingzhong WANG Shiteng RUI Shaokun YANG Weiquan ZHANG Fuyin MA School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an710049China xi’an Precision Machinery research institute Xi’an710077China

To address the incompatibility between high environmental adaptability and deep subwavelength characteristics in conventional local resonance metamaterials,and overcome the deficiencies in the stability of existing active control techniques for band gaps,this paper proposes a design method of pure metal vibration damping metamaterial with continuously tunable stiffness for wideband elastic wave *** design a dual-helix narrow-slit pure metal metamaterial unit,which possesses the triple advantage of high spatial compactness,low stiffness characteristics,and high structural stability,enabling the opening of elastic flexural band gaps in the low-frequency *** to the principle of a sliding rheostat,the introduction of continuously sliding plug-ins into the helical slits enables the continuous variation of the stiffness of the metamaterial unit,achieving a continuously tunable band gap *** successfully extends the effective band gap by more than ten *** experimental results indicate that this metamaterial unit can be used as an additional vibration absorber to absorb the low-frequency vibration energy ***,it advances the metamaterial absorbers from a purely passive narrowband design to a wideband tunable *** pure metal double-helix metamaterials retain the subwavelength properties of metamaterials and are suitable for deployment in harsh ***,by adjusting its stiffness,it substantially broadens the effective band gap range,presenting promising potential applications in various mechanical equipment operating under adverse conditions.

关键词： elastic metamaterial absorber continuously tunable stiffness low-frequency vibration damping variable stiffness design pure metal structure

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Data-Driven Design for Targeted Regulation of Heat Transfer in Carbon/Carbon Composite Structure

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Journal of Thermal Science 2024年第2期33卷 648-657页

作者： xiAO Heye WANG Zelin WANG Hui JI Ritian Unmanned System research institute Northwestern Polytechnical UniversityXi’an710072China School of Aeronautics Northwestern Polytechnical UniversityXi’an710072China research&Development institute of Northwestern Polytechnical university in shenzhen Shenzhen518063China MOE Key Laboratory of Thermo-Fluid Science and Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China

Targeted regulation of heat transfer in carbon/carbon composite structure is built for cooling electronic device.A three-dimensional data-driven design model coupling genetic algorithm(GA) with self-adaption deep learning for targeted regulation of heat transfer in built structure is *** self-adaption deep learning model predicts the temperature of built structure closer to optimal value in GA *** distributions of pore and carbon fiber bundles in built structure are optimized by the proposed *** surface temperature of electronic device in the optimized structures is 19.1%-27.5% lower than that in the initial configurations when the porosity of built structure varies from 3% to 11%.The surface temperature of electronic device increases with an increase in *** built structure with carbon fiber bundles near the surface of electronic device and pore distribution in the middle of structure has a higher heat dissipation capacity compared with that in the initial ***,the computation time of the proposed model is less than one tenth compared with that of the traditional genetic algorithm.

关键词： targeted regulation of heat transfer self-adaption deep learning genetic algorithm carbon/carbon composite structure

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Application of sparse S transform network with knowledge distillation in seismic attenuation delineation

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Petroleum Science 2024年第4期21卷 2345-2355页

作者： Nai-Hao Liu Yu-xin Zhang Yang Yang Rong-Chang Liu Jing-Huai Gao Nan Zhang School of Information and Communications Engineering Xi'an Jiaotong University School of Software Engineering Xi'an Jiaotong University PetroChina research institute of Petroleum Exploration and Development (RIPED) CNPC research institute of Exploration and Development Yumen Oilfield Company CNPC

Time-frequency analysis is a successfully used tool for analyzing the local features of seismic ***, it suffers from several inevitable limitations, such as the restricted time-frequency resolution,the difficulty in selecting parameters, and the low computational efficiency. Inspired by deep learning,we suggest a deep learning-based workflow for seismic time-frequency analysis. The sparse S transform network(SSTNet) is first built to map the relationship between synthetic traces and sparse S transform spectra, which can be easily pre-trained by using synthetic traces and training labels. Next, we introduce knowledge distillation(KD) based transfer learning to re-train SSTNet by using a field data set without training labels, which is named the sparse S transform network with knowledge distillation(KD-SSTNet).In this way, we can effectively calculate the sparse time-frequency spectra of field data and avoid the use of field training labels. To test the availability of the suggested KD-SSTNet, we apply it to field data to estimate seismic attenuation for reservoir characterization and make detailed comparisons with the traditional time-frequency analysis methods.

关键词： S transform Deep learning Knowledge distillation Transfer learning Seismic attenuation delineation

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Reheat effect on the improvement in efficiency of the turbine driven by pulse detonation

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Defence Technology（防务技术） 2024年第1期31卷 200-210页

作者： Junyu Liu Zhiwu Wang Zixu Zhang Junlin Li Weifeng Qin Jingjing Huang School of Power and Energy Northwestern Polytechnical UniversityXi’an 710072China shenzhen research institute of Northwestern Polytechnical university Shenzhen 518057China Mechanical Engineering College Xi’an Shiyou UniversityXi’an 710065China

Due to the strong unsteadiness of pulse detonation,large flow losses are generated when the detonation wave interacts with the turbine blades,resulting in low turbine *** that the flow losses are dissipated into the gas as heat energy,some of them can be recycled during the expansion process in subsequent stages by the reheat effect,which should be helpful to improve the detonationdriven turbine *** this into account,this paper developed a numerical model of the detonation chamber coupled with a two-stage axial turbine,and a stoichiometric hydrogen-air mixture was *** improvement in turbine efficiency attributable to the reheat effect was calculated by comparing the average efficiency of the stages with the efficiency of the two-stage *** research indicated that the first stage was critical in suppressing the flow unsteadiness caused by pulse detonation,which stabilized the intake condition of the second stage and consequently allowed much of the flow losses from the first stage to be recycled,so that the efficiency of the two-stage turbine was *** a 95%confidence level,the efficiency improvement was stable at 4.5%—5.3%,demonstrating that the reheat effect is significant in improving the efficiency of the detonation-driven turbine.

关键词： Pulse detonation turbine engine Hydrogen detonation Turbine efficiency Reheat effect Multi-cycle detonation

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MGMT activated by Wnt pathway promotes cisplatin tolerance through inducing slow-cycling cells and nonhomologous end joining in colorectal cancer

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Journal of Pharmaceutical Analysis 2024年第6期14卷 863-877页

作者： Haowei Zhang Qixin Li xiaolong Guo Hong Wu Chenhao Hu Gaixia Liu Tianyu Yu xiake Hu Quanpeng Qiu Gang Guo Junjun She Yinnan Chen Department of General Surgery The First Affiliated Hospital of Xi'an Jiaotong UniversityXi'an710061China Center for Gut Microbiome research Med-X InstituteThe First Affiliated Hospital of Xi'an Jiaotong UniversityXi'an710061China Department of High Talent The First Affiliated Hospital of Xi'an Jiaotong UniversityXi'an710061China

Chemotherapy resistance plays a pivotal role in the prognosis and therapeutic failure of patients with colorectal cancer(CRC).Cisplatin(DDP)-resistant cells exhibit an inherent ability to evade the toxic chemotherapeutic drug effects which are characterized by the activation of slow-cycle programs and DNA *** the elements that lead to DDP resistance,O^(6)-methylguanine(O^(6)-MG)-DNA-methyltransferase(MGMT),a DNA-repair enzyme,performs a quintessential *** this study,we clarify the significant involvement of MGMT in conferring DDP resistance in CRC,elucidating the underlying mechanism of the regulatory actions of MGMT.A notable upregulation of MGMT in DDP-resistant cancer cells was found in our study,and MGMT repression amplifies the sensitivity of these cells to DDP treatment in vitro and in ***,in cancer cells,MGMT overexpression abolishes their sensitivity to DDP ***,the interaction between MGMT and cyclin dependent kinase 1(CDK1)inducing slow-cycling cells is attainted via the promotion of ubiquitination degradation of ***,to achieve nonhomologous end joining,MGMT interacts with XRCC6 to resist chemotherapy *** transcriptome data from samples of 88 patients with CRC suggest that MGMT expression is co-related with the Wnt signaling pathway activation,and several Wnt inhibitors can repress drug-resistant *** summary,our results point out that MGMT is a potential therapeutic target and predictive marker of chemoresistance in CRC.

关键词： Colorectal cancer MGMT Chemotherapy resistance Slow-cycling cells Nonhomologous end joining Wnt pathway

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Piezoelectric Drop-on-Demand Inkjet Printing with Ultra-High Droplet Velocity

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research 2024年第3期2023卷 123-137页

作者： Zhengjie Yang Hongmiao Tian Chunhui Wang xiangming Li xiaoliang Chen xiaoming Chen Jinyou Shao State Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’anShaanxi 710049China Frontier institute of Science and Technology(FIST) Xi’an Jiaotong UniversityXi’anShaanxi 710049China.

Improving droplet velocity as much as possible is considered as the key to improving both printing speed and printing distance of the piezoelectric drop-on-demand inkjet printing *** are 3 tough and contradictory issues that need to be addressed simultaneously,namely,the actuation pressure of the piezoelectric printhead,satellite droplets,and the air resistance,which seems almost impossible to achieve with classical ***,a novel solution is *** modulating the positive crosstalk effect inside and outside the printhead,self-tuning can be achieved,including self-reinforcing of the actuation pressure,self-restraining of satellite droplets,and self-weakening of the air resistance,thereby greatly improving droplet *** on these mechanisms,waveform design methods for different inks and printheads are *** results demonstrate that monodisperse droplet jetting with a maximum velocity of 27.53 m/s can be achieved,reaching 3 to 5 times that of the classical method(5 to 8 m/s).Correspondingly,the printing speed and distance can be simultaneously increased by almost 10 times,demonstrating an ability of direct printing on irregular ***,the compatibility of ink materials is expanded,as the Ohnesorge number and the viscosity of printable inks for the printhead used are increased from 0.36–0.72 to 0.03–1.18 and from 10–12 cp to 1–40.3 cp,respectively,even breaking the traditional limitations of the piezoelectric printing technology(Ohnesorge number of 0.1 to 1;viscosity of 1 to 25 cp).All the above provide a new perspective for improving droplet velocity and may even offer a game-changing choice for expanding the boundaries of the piezoelectric drop-on-demand inkjet printing technology.

关键词： piezoelectric viscosity thereby

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Enhancing electrolyte ion diffusion via direct ink writing pillar array structure of graphene electrodes for high-performance microsupercapacitors

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Nano research 2024年第7期17卷 6203-6211页

作者： Yan Zhang Huandi Zhang xiaoxiao Wang Cheng Tang xiaowei Shi Zehua Zhao Jiamei Liu Guolong Wang Jianfeng Shen Lei Li State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong University28 Xianning West RoadXi’an 710049China Center for Materials Chemistry Frontier Institute of Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China Instrument Analysis Center of xi'an jiaotong university Xi’an Jiaotong University28 Xianning West RoadXi’an 710049China institute of special materials and technology Fudan UniversityShanghai 200433China

The graphene-based microsupercapacitors(MSCs)suffer from graphene aggregation issue in *** reduces the electrolyte ions transportation in the electrodes to degrade the charge storage ability of MSCs,hampering their practical *** the electrolyte ions transportation in the electrodes can boost the charge storage ability of ***,we design and experimentally realize pillar array structure of graphene electrodes for MSCs by direct ink writing *** graphene electrodes with pillar array structure increase the contact area with electrolyte and short the electrolyte ions transport path,facilitating electrolyte ions transport in *** MSCs exhibit high areal capacitance of 25.67 mF·cm^(−2),high areal energy density of 20.54μWh·cm^(−2),and high power density of 1.45 mW·cm^(−2).One single MSCs can power timer for 10 min and pressure sensor more than 160 min,showing high practical application *** work provides a new avenue for developing high performance MSCs.

关键词： microsupercapacitors pillar array structure direct ink writing areal energy density ion transport

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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

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research progress of slippage characteristic and gas film stability enhancement methods on biomimetic hydrophobic surfaces

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Journal of Hydrodynamics 2024年第1期36卷 87-101页

作者： Meng-zhuo Zhang Hai-bao Hu Liu-zhen Ren Lu-yao Bao Jun Wen Luo xie School of Marine Science and Technology Northwestern Polytechnical UniversityXi’an710072China research and Development institute of Northwestern Polytechnical university in shenzhen Shenzhen518063China

The biomimetic hydrophobic surface is a potentially efficient underwater drag reduction method and the drag reduction mechanism of this kind of surface comes from the interfacial *** now,it is a hotspot to grasp the slippage characteristic and explore slippage enhancement *** paper not only summarizes our numerical simulation and experimental results of slippage characteristic at the solid-liquid interface(SLI)of hydrophobic surfaces(HS)and the gas-liquid interface(GLI)of superhydrophobic surfaces(SHS)in recent years,but also introduces some innovative methods that can effectively improve the gas film stability and drag reduction effect of ***,we used the molecular dynamics(MD)simulation method to figure out the effect of the solid-liquid interaction strength,the system temperature and the shear rate on the slippage of SLI,and expound their action mechanism from molecular ***,by MD and multibody dissipative particle dynamics(MDPD)method,the slippage behavior at the GLI was studied under the influence of the microstructure size and the flow driving *** proposed a new kind of hybrid slip boundary condition model to describe the slippage characteristic on *** addition,we found through experiment that a three-dimensional backflow will appear on the GLI under the interfacial adsorption of surfactants,and the backflow direction will reverse with the change of GLI ***,we put forward the wettability step structure and gas injection method to enhance the stability and drag reduction effect of the gas film on SHS.

关键词： Hydrophobic surface superhydrophobic surface interfacial slip underwater drag reduction

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Highly efficient photo-thermal synergistic catalysis of CO_(2)methanation over La_(1-x)Ce_(x)NiO_(3)perovskite-catalyst

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Nano research 2024年第9期17卷 7945-7956页

作者： Ting Li Zhen-Yu Zhang De-Cun Luo Bo-Yu Xu Rong-Jiang Zhang Ji-Long Yao Dan Li Tao xie institute of Industrial Catalysis School of Chemical Engineering and TechnologyXi’an Jiaotong UniversityXi’an 710049China

Solar-driven photo-thermal catalytic CO_(2)methanation reaction is a promising technology to alleviate the problems posed by greenhouse gases ***,designing advanced photo-thermal catalysts remains a research challenge for CO_(2)methanation *** this work,a series of ABO3(A=lanthanide,B=transition metal)perovskite catalysts with Ce-substituted LaNiO3(La_(1-x)Ce_(x)NiO_(3),x=0,0.2,0.5,0.8,1)were synthesized for CO_(2)*** La_(0.2)Ce_(0.8)NiO_(3) exhibited the highest CH_(4) formation rate of 258.9 mmol·g^(-1)·hcat-1,CO_(2)conversion of 55.4%and 97.2%CH_(4) selectivity at 300℃with the light intensity of 2.9 W·cm^(-2).Then the catalysts were thoroughly analyzed by physicochemical structure and optical properties *** partial substitution of the A-site provided more active sites for the adsorption and activation of CO_(2)/H_(2).The sources of the active sites were considered to be the oxygen vacancies(O_(v))created by lattice distortions due to different species of ions(La^(3+),Ce^(4+),Ce^(3+))and exsolved Ni0 by H_(2)*** catalysts have excellent light absorption absorbance and low electron-hole(e^(-)/h^(+))recombination rate,which greatly contribute to the excellent performance in photo-thermal synergistic catalysis(PTC)CO_(2)*** results of in situ irradiated electron paramagnetic resonance spectrometer(ISI-EPR)and ISI-X-ray photoelectron spectroscopy(XPS)indicated that the aggregation of unpaired electrons near the defects and Ni metal(from La and Ce ions to Ov and Ni0)accelerated adsorption and activation of CO_(2)/H_(2).At last,the catalyst properties and structure were correlated with the proposed reaction mechanism from the in situ diffuse reflection infrared Fourier transform spectrum(DRIFTS)*** in situ precipitation of the B-site enhanced the dispersion of Ni,while its enriched photoelectrons upon illumination further promote hydrogen *** H^(*)spillover accelerated t

关键词： photo-thermal catalysis CO_(2)methanation perovskite A-site substitution in situ diffuse reflection infrared Fourier transform spectrum(DRIFTS)

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