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Fractal-Based Acoustic Metamaterials Coupling with Micro-Perforation for Low-Frequency Sound Absorption 认领 引用
1
作者 Dongxing Cao Liming Wang +3 位作者 Junru Wang Jianfei Wang Xiangying Guo Shuai Huang 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2026年第2期201-217,共17页
Acoustic metamaterials(AMs)exhibit outstanding sound absorption performance due to their customizable design.In this work,a low-frequency sound-absorbing metamaterial plate,which combines a fractal-based labyrinth aco... Acoustic metamaterials(AMs)exhibit outstanding sound absorption performance due to their customizable design.In this work,a low-frequency sound-absorbing metamaterial plate,which combines a fractal-based labyrinth acoustic metamaterial(FLAM)and a micro-perforation panel,is proposed.The theoretical,simulation,and experimental methods are used to comprehensively examine the sound absorption performance.A triangular fractal curve is first introduced,and the combined FLAM model is constructed.An equivalent straight channel model is developed to study the effects of the structural parameters on the sound absorption coefficients.The finite element analysis(FEA)is further conducted to validate the theoretical results.All the findings indicate that the proposed combined FLAM exhibits excellent sound absorption performance at a deep sub-wavelength scale,with absorption coefficients of 0.89,0.98,and 1.00 for the first three fractal orders,respectively.Finally,the prototypes are fabricated,and the impedance tube experiments are conducted,yielding results that align closely with both analytical and FEA results.Notably,the sound absorption performance of large-area sound-absorbing plates is also investigated by splicing two/four FLAMs together,demonstrating a relative absorption bandwidth exceeding 35%.This work offers a viable alternative to low-frequency sound-absorbing materials for potential engineering applications. 展开更多
关键词 Fractal-based acoustic metamaterial(AM) Low-frequency sound absorption Deep sub-wavelength Impedance tube experiment
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Low-frequency signal inversion and reconstruction via the spatial structure regularization 认领 引用
2
作者 Wei-wei Gu Hao Li +2 位作者 Dong-feng Zhao Peng-fei Wang Guo-fa Li 《Applied Geophysics》 SCIE CSCD 2026年第1期125-137,429,共13页
Low-frequency signals play a crucial role in seismic inversion of thin-layer structure and reservoir prediction.However,during seismic exploration,the low-frequency signals are often contaminated,distorted,or even mis... Low-frequency signals play a crucial role in seismic inversion of thin-layer structure and reservoir prediction.However,during seismic exploration,the low-frequency signals are often contaminated,distorted,or even missing due to acquisition limitations,processing artifacts,and ambient noise.Although compressive sensing theory-based sparse inversion can partially recover low-frequency signals,the reconstruction results suffer from significant non-uniqueness.To address this challenge,we propose a sparse inversion approach incorporating spatial structural regularization to enhance low-frequency signal recovery.Due to the interference among seismic waveforms,spatial reflection structure exhibits frequency dependency.Consequently,the spatial structure estimated directly from seismic data differs significantly from the actual low-frequency spatial structure.Therefore,the proposed method estimates spatial reflection structure from seismic data in the neighboring frequency band of the low-frequency signals to be recovered,aiming to reduce the impact of frequency dependency on estimation accuracy.Subsequently,both the sparse structure of reflection coefcients and spatial structure of low-frequency signals are incorporated as regularization terms into the inversion framework,enabling geologically guided recovery of low-frequency components.The proposed method was successfully applied in the Tarim Oileld,eectively restoring low-frequency signals and providing reliable foundational seismic data for reservoir prediction. 展开更多
关键词 Spatial structure Structure tensor Low-frequency signals Sparse inversion
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Low-Frequency Ultrasonic Array Imaging of Interlayer Voids Hidden in Ballastless Track Structure of High-Speed Railway 认领 引用
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作者 Guopeng Fan Xuefeng Chen +1 位作者 Hao Liu Jiaqing Zheng 《Structural Durability & Health Monitoring》 EI 2026年第4期88-117,共30页
Low-frequency ultrasonic array is commonly used to detect interlayer voids located in high-speed railway ballastless track,which is a typical multilayer concrete bonded structure.The difficulty of detection lies in th... Low-frequency ultrasonic array is commonly used to detect interlayer voids located in high-speed railway ballastless track,which is a typical multilayer concrete bonded structure.The difficulty of detection lies in the fact that the total focusingmethod(TFM)based on a single fixed sound velocity model cannot adapt to the acoustic propagation characteristics of multilayer structures,which is prone to generating artifacts.In addition,the long duration of lowfrequency ultrasonic pulses is prone to causing significant deviations in defect localization.To address these issues,a theoretical model of the layered bonded structure is proposed.The acoustic wave propagation path and travel time calculation are clarified after combining the Fermat’s principle and Snell’s law,and the shortest path ray tracing(SPRT)is proposed,which achieves visual imaging of interlayer voids;The pulse peak delay(PPD)is applied to correct the travel time of low-frequency ultrasonic waves,and the shortest path ray tracing combined with pulse peak delay(PSPRT)is proposed,which significantly improves the localization accuracy of defects.Finally,by integrating the amplitude and phase information of scattered signals,the shortest path ray tracing based on pulse peak delay and sign coherence factor(PPSPRT)is constructed,which significantly enhances the SNR.The test results show that,compared with the conventional TFM,the proposed PPSPRT achieves average SNR improvements of 6.62 dB in numerical simulations and 14.30 dB in field tests,and reduces the average depth localization error of interlayer voids to merely 23.49%and 10.38%of that of TFM under corresponding test conditions,respectively.PPSPRT can provide important guidance for accurate imaging of interlayer voids. 展开更多
关键词 Low-frequency ultrasonic array interlayer voids bonded structure ray tracing localization accuracy
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Customized acousto-mechanical metastructure for broadband low-frequency sound absorption and vibration isolation via optimization design 认领 引用
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作者 Zonghan Li Changzhi Hu +1 位作者 Zhiwen Ren Mingji Chen 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第5期596-611,共16页
The demand for noise and vibration control in aerospace and vehicle manufacturing is increasing,but reliable design strategies are still lacking.Here,an integrated acousto-mechanical metastructure is proposed to reali... The demand for noise and vibration control in aerospace and vehicle manufacturing is increasing,but reliable design strategies are still lacking.Here,an integrated acousto-mechanical metastructure is proposed to realize broadband lowfrequency sound absorption and vibration isolation simultaneously.Due to the introduction of bistable substructures,the proposed metastructure achieves quasi-zero stiffness vibration isolation and sound energy dissipation without external loads.Rapid customized design of the optimized metastructure is achieved by the proposed optimization algorithm.An average sound absorption coefficient of 0.8 is realized by optimization design within the frequency range of 350 Hz to 800 Hz.In addition,the proposed acousto-mechanical metastructure exhibits ultra-low broadband vibration isolation performance,with an initial isolation frequency of 40.4 Hz.Theoretical calculations,numerical simulations,and experimental results show that the acoustic performance of the metastructure benefits from the intensive mode density brought by multiple geometric degrees of freedom,while its vibration isolation performance originates from the quasi-zero stiffness beams.Overall,a multi-objective optimization method under a given structural design domain is proposed to optimize the multifunctional metastructure. 展开更多
关键词 Acousto-mechanical metastructure Non-local resonator Sound absorption Vibration isolation Broadband low-frequency
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Altered amplitudes of low-frequency fluctuations in primary open angle glaucoma patients:a resting-state fMRI study 认领 引用
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作者 Yi Huang Hong-Dou Luo +7 位作者 Yong-Qiang Shu Feng Ouyang Yu-Ning Song Yuan-Yuan Wang Xue-Qing Yu Chan Xiong Lu Yang Xu Zhang 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2026年第2期291-301,共11页
AIM:To study the relationships between amplitude of low-frequency fluctuations(ALFF)changes and clinical ophthalmic parameters in patients with primary open angle glaucoma(POAG)and analyze the diagnostic value of ALFF... AIM:To study the relationships between amplitude of low-frequency fluctuations(ALFF)changes and clinical ophthalmic parameters in patients with primary open angle glaucoma(POAG)and analyze the diagnostic value of ALFF.METHODS:Twenty-four POAG patients and 24 healthy controls(HCs)underwent resting-state functional magnetic resonance imaging(rs-fMRI).Nonparametric rank-sum tests were used to compare the ALFF values in the slow-4 and slow-5 bands,and Spearman or Pearson correlation analysis was used to assess the correlation between ALFF changes and clinical ophthalmic parameters in POAG patients.Receiver operating characteristic(ROC)curves were used to evaluate the diagnostic performance of the ALFF.RESULTS:There were 16 males in POAG patients(median age 48y)and 12 males in HCs(median age 39y).Compared with HCs,POAG patients presented increased or decreased ALFF values in different brain regions,and similar changes were observed in mild POAG patients.The ALFF values were correlated with retinal nerve fiber layer(RNFL)thickness,inner limiting membrane-retinal pigment epithelium thickness changes and the degree of visual field defects.Analysis of the diagnostic value of the ALFF via ROC curves revealed that the right medial frontal gyrus[area under the curve(AUC)=0.9063]and superior frontal gyrus(AUC=0.9097)had better diagnostic value than did the optic disc area(AUC=0.8019),visual field index(VFI%,AUC=0.8988)and macular parameters.CONCLUSION:POAG patients present altered cortical function that is significantly correlated with the optic nerve and retinal thickness and had good diagnostic value,which may reflect the underlying neuropathological mechanism of POAG. 展开更多
关键词 primary open angle glaucoma restingstate functional magnetic resonance imaging low-frequency amplitude neurodegenerative disease
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Low-frequency high-power compact transducer based on negative stiffness structure 认领 引用
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作者 Yaojun Guan Yang Gao 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第3期631-642,共12页
High-power extremely low-frequency(ELF)sound sources are essential in marine engineering,and electromagnetic transducers(EMTs)are preferred over piezoelectric and magnetostrictive transducers because of their superior... High-power extremely low-frequency(ELF)sound sources are essential in marine engineering,and electromagnetic transducers(EMTs)are preferred over piezoelectric and magnetostrictive transducers because of their superior output power and compactness.However,achieving high sound pressure levels(SPLs)below 50 Hz in compact EMTs is challenging.In our study,EMT diaphragms were optimized using a negative stiffness structure(NSS)to reduce the stiffness of the vibration system,thereby reducing frequency requirements and increasing output power,as validated by finite element analysis.The NSS diaphragm significantly outperformed conventional designs,increasing transducer output power by 216.23%,achieving a maximum SPL of 170 dB and over 160 dB from 4 to 50 Hz.With dimensions of 150 mm radius and 200 mm height,the EMT is an example of compact design.This research has successfully developed a low-frequency,high power,compact EMT that will enhance offshore technology and research and provide an improved solution for high power ELF sound sources,significantly advancing EMT applications in marine engineering. 展开更多
关键词 Negative stiffness Magnetic circuit design Electromagnetic transducer Finite element analysis Low-frequency high-power miniaturized structure
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Low-Frequency Oscillation Analysis of Grid-Forming Energy Storage Converters Based on a Multi-Damping Path Model 认领 引用
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作者 Qiang Liu Yongqiang Zhou +4 位作者 Chaoyang Lu Zhen Yan Gangui Yan Cheng Yang Yupeng Wang 《Energy Engineering》 EI 2026年第9期443-471,共29页
The increasing proportion of power generated by new energy has meant that grid-forming energy storage has become a key method for improving power grid flexibility.However,the small disturbance stability problem has be... The increasing proportion of power generated by new energy has meant that grid-forming energy storage has become a key method for improving power grid flexibility.However,the small disturbance stability problem has become an important challenge.The issue is that grid-forming energy storage is prone to low-frequency oscillation under strong grid conditions.Therefore,this study proposes a multi damping torque model to analyze the small signal stability of grid-forming energy storage converters.The impact of grid strength,operating conditions,and control parameters on the damping characteristics of the low-frequency oscillation by the system was quantitatively evaluated.The results revealed the mechanism underlying the low-frequency oscillation associated with grid-forming energy storage under strong grid conditions and key factors controlling the low-frequency oscillation.The results also provide theoretical guidance for the tuning of grid-forming energy storage control parameters.The accuracy of the multi damping torque model and theoretical analysis were verified using the electromagnetic simulation results. 展开更多
关键词 Multi-damping path grid-forming energy storage small signal stability low-frequency oscillation
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Lightweight multifunctional metamaterial with low-frequency vibroacoustic reduction and load-bearing performances 认领 引用 被引量：3
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作者 Qi JIA Dianlong YU +1 位作者 Donghai HAN Jihong WEN 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2025年第3期403-422,共20页
Metamaterials can control and manipulate acoustic/elastic waves on a subwavelength scale using cavities or additional components.However,the large cavity and weak stiffness components of traditional metamaterials may ... Metamaterials can control and manipulate acoustic/elastic waves on a subwavelength scale using cavities or additional components.However,the large cavity and weak stiffness components of traditional metamaterials may cause a conflict between vibroacoustic reduction and load-bearing capacity,and thus limit their application.Here,we propose a lightweight multifunctional metamaterial that can simultaneously achieve low-frequency sound insulation,broadband vibration reduction,and excellent load-bearing performance,named as vibroacoustic isolation and bearing metamaterial(VIBM).The advent of additive manufacturing technology provides a convenient and reliable method for the fabrication of VIBM samples.The results show that the compressive strength of the VIBM is as high as 9.71 MPa,which is nearly 87.81%higher than that of the conventional grid structure(CGS)under the same volume fraction.Moreover,the vibration and sound transmission are significantly reduced over a low and wide frequency range,which agrees well with the experimental data,and the reduction degree is obviously larger than that obtained by the CGS.The design strategy can effectively realize the key components of metamaterials and improve their application scenarios. 展开更多
关键词 multifunctional metamaterial low-frequency sound insulation broadband vibration reduction load bearing
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Low-Frequency Sweep Design—A Case Study in Middle East Desert Environments 认领 引用 被引量：2
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作者 Qi Yong-fei Wei Zhou-hong +7 位作者 Nie Ming-tao Li Guo-fa Wang Tao Ling Hai Cong Sheng-kui Chen Xin-yang Duan Chang-ping Liu Yang 《Applied Geophysics》 SCIE CSCD 2025年第1期71-83,233,共13页
Low-frequency vibroseis acquisition has become a routine operation in land seismic surveys,given the advantages of low-frequency signals in characterizing geological structures and enhancing the imaging of deep explor... Low-frequency vibroseis acquisition has become a routine operation in land seismic surveys,given the advantages of low-frequency signals in characterizing geological structures and enhancing the imaging of deep exploration targets.The two key points of low-frequency sweep design techniques include controlling the distortion and improving the output energy during the low-frequency stage.However,the vibrators are limited by the maximum fl ow provided by the hydraulic systems at the low-frequency stage,causing difficulty in satisfying exploration energy requirements.Initially,a theoretical analysis of the low-frequency acquisition performance of vibrators is conducted.A theoretical maximum output force below 10 Hz is obtained by guiding through theoretical formulas and combining actual vibrator parameters.Then,the signal is optimized according to the surface characteristics of the operation area.Finally,detailed application quality control and operational procedures are established.The new low-frequency sweep design method has overcome the maximum flow limitations of the hydraulic system,increased the low-frequency energy,and achieved broadband acquisition.The designed signal has been tested and applied on various types of ground surfaces in the Middle East desert region,yielding good performance.The proposed low-frequency sweep design method holds considerable value for the application of conventional vibroseis in low-frequency acquisition. 展开更多
关键词 Vibroseis Low-frequency sweep design
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Low-frequency chatter suppression in robotic milling using Magnetorheological Joint Damper(MRJD) 认领 引用 被引量：2
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作者 Shihao XIN Xiaowei TANG +3 位作者 Jiawei WU Fangyu PENG Rong YAN Kai SUN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2025年第3期521-543,共23页
Low-frequency structural vibrations caused by poor rigidity are one of the main obstacles limiting the machining efficiency of robotic milling.Existing vibration suppression strategies primarily focus on passive vibra... Low-frequency structural vibrations caused by poor rigidity are one of the main obstacles limiting the machining efficiency of robotic milling.Existing vibration suppression strategies primarily focus on passive vibration absorption at the robotic end and feedback control at the joint motor.Although these strategies have a certain vibration suppression effect,the limitations of robotic flexibility and the extremely limited applicable speed range remain to be overcome.In this study,a Magnetorheological Joint Damper(MRJD)is developed.The joint-mounted feature ensures machining flexibility of the robot,and the millisecond response time of the Magnetorheological Fluid(MRF)ensures a large effective spindle speed range.More importantly,the evolution law of the damping performance of MRJD was revealed based on a low-frequency chatter mechanism,which guarantees the application of MRJD in robotic milling machining.To analyze the influence of the robotic joint angle on the suppression effect of the MRJD,the joint braking coefficient and end braking coefficient were proposed.Parallel coordinate plots were used to visualize the joint range with the optimal vibration suppression effect.Finally,a combination of different postures and cutting parameters was used to verify the vibration suppression effect and feasibility of the joint angle optimization.The experimental results show that the MRJD,which directly improves the joint vibration resistance,can effectively suppress the low-frequency vibration of robotic milling under a variety of cutting conditions. 展开更多
关键词 Magnetorheological fluids Joint damper Vibration suppressioni Low-frequency chatter Robotic milling
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Low-frequency vibration suppression of meta-beam with softening nonlinearity 认领 引用 被引量：2
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作者 Weixing ZHANG Dongshuo YANG Xiangying GUO 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2025年第6期1011-1028,共18页
In order to obtain a lower frequency band gap,this paper proposes a novel locally resonant meta-beam incorporating a softening nonlinear factor.An improved camroller structure is designed in this meta-beam to achieve ... In order to obtain a lower frequency band gap,this paper proposes a novel locally resonant meta-beam incorporating a softening nonlinear factor.An improved camroller structure is designed in this meta-beam to achieve the softening nonlinear stiffness of the local oscillators.Firstly,based on Hamilton's principle and the Galerkin method,the control equations for the coupled system are established.The theoretical band gap boundary is then derived with the modal analysis method.The theoretical results reveal that the band gap of the meta-beam shifts towards lower frequencies due to the presence of a softening nonlinear factor,distinguishing it from both linear metamaterials and those with hardening nonlinear characteristics.Then,the vibration attenuation characteristics of a finite size meta-beam are investigated through numerical calculation,and are verified by the theoretical results.Furthermore,parameter studies indicate that the reasonable design of the local oscillator parameters based on lightweight principles helps to achieve further broadband and efficient vibration reduction in the low-frequency region.Finally,a prototype of the meta-beam is fabricated and assembled,and the formations of the low-frequency band gap and the amplitude-induced band gap phenomenon are verified through experiments. 展开更多
关键词 softening nonlinearity nonlinear band gap meta-beam low-frequency vibration attenuation
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Electrical performance optimization and low-frequency noise evaluation of In2O3 TFT with CeAlOx/Al2O3 stacked gate dielectrics 认领 引用 被引量：1
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作者 Lei-Ni Wang Gang He +5 位作者 Jian-Guo Lv Hai Yu Wen-Hao Wang Yang Hu Peng-Yu Hu Chen Qiu 《Rare Metals》 SCIE EI CAS CSCD 2025年第12期10567-10579,共13页
This article reports In2O3 thin-film transistors(TFTs) that utilize a CeAlOx/Al2O3 stacked gate dielectric architecture.The CeAlOx gate dielectric films were optimized by doping Al into CeO2,where... This article reports In2O3 thin-film transistors(TFTs) that utilize a CeAlOx/Al2O3 stacked gate dielectric architecture.The CeAlOx gate dielectric films were optimized by doping Al into CeO2,where the adjustment of the Al/Ce atomic ratio effectively suppressed oxygen-vacancy-related defects and optimized gate dielectric leakage current.Due to the large bandgap and high density of Al2O3 prepared via atomic layer deposition(ALD),CeAlOx/Al2O3 stacked gate dielectric exhibits lower leakage current compared to single-layer CeAlOx.We systematically investigated the Al/Ce ratio's dependence on In2O3 TFT performance,identifying an optimal stoichiometry of 3:7(Al:Ce).The CeAlOx/Al2O3-based In2O3 TFT fabricated at this ratio achieved exceptional characteristics:higher saturation mobility(26.86 cm2 V-1 s-1) and on/off current ratio(3.58×107),lower sub threshold swing(0.08 V decade-1) and interface state density(1.39×1012 cm-2),coupled with excellent bias stress stability.By combining low-frequency noise analysis and X-ray photoelectron spectroscopy(XPS),we confirmed that Al doping reduces the trap density in CeO2 while simultaneously enhancing its dielectric properties.Furthermore,a resistive-load inverter based on In2O3 TFT presents a voltage gain up to 15.1 at an applied voltage of 5 V with a typical reverse behavior,demonstrating that In2O3 TFT based on CeAlOx/Al2O3 stacked gate dielectric exhibits potential for application in advanced digital circuits. 展开更多
关键词 CeAlOx Stack gate dielectrics Interfacial state density Inverter Low-frequency noise
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4D Printing of Reconfigurable Acoustic Metamaterials with Multiband Low-Frequency Absorption 认领 引用 被引量：1
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作者 Jiajie Luo Junxiang Fan +7 位作者 Bo Song Yintang Wen Xiaobo Wang Lei Zhang Yonggang Yao Xiao Xiang Xuefeng Zhu Yusheng Shi 《Additive Manufacturing Frontiers》 CSCD 2025年第1期18-28,共11页
Controlling low-frequency noise presents a significant challenge for traditional sound absorption materials,such as foams and fibrous substances.Recently developed acoustic absorption metamaterials,which rely on local... Controlling low-frequency noise presents a significant challenge for traditional sound absorption materials,such as foams and fibrous substances.Recently developed acoustic absorption metamaterials,which rely on local resonance can effectively balance the volume occupation and low-frequency absorption performance.However,these materials often exhibit a very narrow and fixed absorption band.Inspired by Helmholtz resonators and bistable structures,we propose bistable reconfigurable acoustic metamaterials(BRAMs)that offer multiband low-frequency absorption.These BRAMs are fabricated using shape-memory polylactic acid(SM-PLA)via four-dimension(4D)printing technology.Consequently,the geometry and absorption performance of the BRAMs can be adjusted by applying thermal stimuli(at 55℃)to switch between two stable states.The BRAMs demonstrate excellent low-frequency absorption with multiband characteristics,achieving an absorption coefficient of 0.981 at 136 Hz and 0.998 at 230 Hz for stable state I,and coefficients of 0.984 at 156 Hz and 0.961 at 542 Hz for stable state II.It was found that the BRAMs with different inclined plate angles had linear recovery stages,and the recovery speeds range from 0.75 mm/s to 1.1 mm/s.By combining a rational structural design and 4D printing,the reported reconfigurable acoustic metamaterials will inspire further studies on the design of dynamic and broadband absorption devices. 展开更多
关键词 4D printing Low-frequency absorption Bistable structure Acoustic metamaterials
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Detection and Tracking of a UAV Based on Low-Frequency Communication Network 认领 引用
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作者 Hongmei Shi Yifan Zhou +1 位作者 Mengxin Yang Dan Zeng 《Journal of Beijing Institute of Technology》 EI CAS 2025年第3期231-242,共12页
When tracking a unmanned aerial vehicle(UAV)in complex backgrounds,environmen-tal noise and clutter often obscure it.Traditional radar target tracking algorithms face multiple lim-itations when tracking a UAV,includin... When tracking a unmanned aerial vehicle(UAV)in complex backgrounds,environmen-tal noise and clutter often obscure it.Traditional radar target tracking algorithms face multiple lim-itations when tracking a UAV,including high vulnerability to target occlusion and shape variations,as well as pronounced false alarms and missed detections in low signal-to-noise ratio(SNR)envi-ronments.To address these issues,this paper proposes a UAV detection and tracking algorithm based on a low-frequency communication network.The accuracy and effectiveness of the algorithm are validated through simulation experiments using field-measured point cloud data.Additionally,the key parameters of the algorithm are optimized through a process of selection and comparison,thereby improving the algorithm's precision.The experimental results show that the improved algo-rithm can significantly enhance the detection and tracking performance of the UAV under high clutter density conditions,effectively reduce the false alarm rate and markedly improve overall tracking performance metrics. 展开更多
关键词 unmanned aerial vehicl(UAV)detection and tracking low-frequency communication network field-measurement data
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Experimental study on Inhibition of Autophagy in Triple-negative Breast Cancer Mice by Microbubble-enhanced Irradiation with Low-frequency Ultrasound 认领 引用
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作者 SHAO Jian-bin FANG Yin 《Chinese Journal of Biomedical Engineering(English Edition)》 CAS 2025年第1期34-39,共6页
Objective: To investigate the role of low-frequency ultrasound(LFUS)combined with microbubble enhancement in inhibiting autophagy in a mouse model of triple-negative breast cancer(TNBC). Methods: A total of 32 SPF-gra... Objective: To investigate the role of low-frequency ultrasound(LFUS)combined with microbubble enhancement in inhibiting autophagy in a mouse model of triple-negative breast cancer(TNBC). Methods: A total of 32 SPF-grade BALB/C mice were randomly divided into four groups: control group, TNBC group, LFUS group, and LFUS+M group. The mice in each group were treated with tail vein injection of normal saline, establishment of TNBC model via tumor xenotransplantation+normal saline injection, LFUS irradiation, and sulfur hexafluoride microbubbles(Sono Vue)+LFUS irradiation, respectively. The tumor growth curves and survival status of TNBC in the four groups of mice were monitored. Western blotting was used to determine the expression level of autophagy-related proteins, and MTT assay and flow cytometry were used to detect the proliferation of mammary tumor cells in each group. Results: Compared with the control group, the tumor volume of mice in the LFUS group and LFUS+M group was significantly reduced. The tumor growth curve of the LFUS group slowed down compared with that of the TNBC group, while the tumor volume of the LFUS+M group decreased significantly on the 4th day, and the tumor tissue growth trend was slower than that of the TNBC group and the LFUS group, and the survival time was prolonged. The Bcl-2 and Bax levels of breast tumor histiocytes in the LFUS+M group were lower than those in the other three groups, Beclin1 was higher than those in the control group and TNBC group,and LC3Ⅱ./LC3Ⅰ was higher than that in the control group and the other two groups(P<0.05). Conclusion: Low-frequency ultrasound microbubble-enhanced irradiation can significantly inhibit the tumor volume growth in TNBC mice, and inhibit their proliferative activity by promoting the autophagy ability of tumor cells, with particularly obvious effects on Bcl-2 and Beclin1, prolonging the survival time of mice. 展开更多
关键词 low-frequency ultrasound(LFUS) microbubble-enhanced irradia-tion triple-negative breast cancer autophagy cell apoptosis
Analyzing the Efficacy of Combining Meridian Flow Low-Frequency Therapy Instrument with Chinese Herbal Enema for the Treatment of Acute and Chronic Pelvic Inflammatory Disease 认领 引用
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作者 Jianfen Bu Miao Hui Yanqun Huang 《Journal of Clinical and Nursing Research》 2025年第12期286-292,共7页
Objective:To study the clinical efficacy of applying the Meridian Flow Low-Frequency Therapy Device combined with Chinese herbal enema for patients with acute and chronic pelvic inflammatory disease(PID).Methods:Sixty... Objective:To study the clinical efficacy of applying the Meridian Flow Low-Frequency Therapy Device combined with Chinese herbal enema for patients with acute and chronic pelvic inflammatory disease(PID).Methods:Sixty-two patients with acute and chronic PID admitted from January 2024 to October 2025 were selected and randomly divided into a standard group(n=31)and an experimental group(n=31).The standard group received conventional medication+Chinese herbal enema treatment.The experimental group received the Meridian Flow Low-Frequency Therapy Device in addition to the standard group’s treatment.The clinical efficacy,changes in inflammatory markers,and pelvic improvement were compared between the two groups.Results:The excellent-good rate of treatment in the experimental group was higher than that in the standard group(p<0.05).The levels of various inflammatory factors in the experimental group were lower than those in the standard group(all p<0.05).The improvement in pelvic mass diameter and pelvic effusion depth in the experimental group was superior to that in the standard group(both p<0.05).Conclusion:The Meridian Flow Low-Frequency Therapy Device combined with Chinese herbal enema has a definite curative effect in treating pelvic inflammatory disease.It can effectively alleviate clinical symptoms,reduce inflammatory response,and promote the improvement of the pelvic environment. 展开更多
关键词 Acute and chronic pelvic inflammatory disease Meridian flow low-frequency therapy device Chinese herbal enema
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A brief review of metamaterials for opening low-frequency band gaps 认领 引用 被引量：15
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作者 Kai WANG Jiaxi ZHOU +3 位作者 Dongguo TAN Zeyi LI Qida LIN Daolin XU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2022年第7期1125-1144,共20页
Metamaterials are an emerging type of man-made material capable of obtaining some extraordinary properties that cannot be realized by naturally occurring materials.Due to tremendous application foregrounds in wave man... Metamaterials are an emerging type of man-made material capable of obtaining some extraordinary properties that cannot be realized by naturally occurring materials.Due to tremendous application foregrounds in wave manipulations,metamaterials have gained more and more attraction.Especially,developing research interest of low-frequency vibration attenuation using metamaterials has emerged in the past decades.To better understand the fundamental principle of opening low-frequency(below 100 Hz)band gaps,a general view on the existing literature related to low-frequency band gaps is presented.In this review,some methods for fulfilling low-frequency band gaps are firstly categorized and detailed,and then several strategies for tuning the low-frequency band gaps are summarized.Finally,the potential applications of this type of metamaterial are briefly listed.This review is expected to provide some inspirations for realizing and tuning the low-frequency band gaps by means of summarizing the related literature. 展开更多
关键词 metamaterial low-frequency band gap vibration suppression
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Enhancing Low-Frequency Microwave Absorption Through Structural Polarization Modulation of MXenes 认领 引用 被引量：19
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作者 Bo Shan Yang Wang +1 位作者 Xinyi Ji Yi Huang 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第10期435-452,共18页
Two-dimensional carbon-based materials have shown promising electromagnetic wave absorption capabilities in mid-and high-frequency ranges,but face challenges in low-frequency absorption due to limited control over pol... Two-dimensional carbon-based materials have shown promising electromagnetic wave absorption capabilities in mid-and high-frequency ranges,but face challenges in low-frequency absorption due to limited control over polarization response mecha-nisms and ambiguous resonance behavior.In this study,we pro-pose a novel approach to enhance absorption efficiency in aligned three-dimensional(3D)MXene/CNF(cellulose nanofibers)cavities by modifying polarization properties and manipulating resonance response in the 3D MXene architecture.This controlled polarization mechanism results in a significant shift of the main absorption region from the X-band to the S-band,leading to a remarkable reflection loss value of-47.9 dB in the low-frequency range.Furthermore,our findings revealed the importance of the oriented electromagnetic coupling in influencing electromagnetic response and microwave absorption properties.The present study inspired us to develop a generic strategy for low-frequency tuned absorption in the absence of magnetic element participation,while orientation-induced polarization and the derived magnetic resonance coupling are the key controlling factors of the method. 展开更多
关键词 Hierarchical structure MXene Microwave absorption Low-frequency
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Low-frequency data analysis and expansion 认领 引用 被引量：29
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作者 张军华 张彬彬 +2 位作者 张在金 梁鸿贤 葛大明 《Applied Geophysics》 SCIE CSCD 2015年第2期212-220,275,共9页
The use of low-frequency seismic data improves the seismic resolution, and the imaging and inversion quality. Furthermore, low-frequency data are applied in hydrocarbon exploration; thus, we need to better use low-fre... The use of low-frequency seismic data improves the seismic resolution, and the imaging and inversion quality. Furthermore, low-frequency data are applied in hydrocarbon exploration; thus, we need to better use low-frequency data. In seismic wavelets, the loss of low-frequency data decreases the main lobe amplitude and increases the first side lobe amplitude and results in the periodic shocking attenuation of the secondary side lobe. The loss of low frequencies likely produces pseudo-events and the false appearance of higher resolution. We use models to examine the removal of low-frequency data in seismic data processing. The results suggest that the removal of low frequencies create distortions, especially for steep structures and thin layers. We also perform low-frequency expansion using compressed sensing and sparse constraints and develop the corresponding module. Finally, we apply the proposed method to real common image point gathers with good results. 展开更多
关键词 seismic wavelet forward modeling low-frequency expansion compressed sensing sparse constraint
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Analysis of the Characteristics of 30-60 Day Low-Frequency Oscillation over Asia during 1998 SCSMEX 认领 引用 被引量：79
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作者 陈隆勋 祝从文 +1 位作者 王文 张培群 《Advances in Atmospheric Sciences》 SCIE CAS 2001年第4期623-638,共16页
The wavelet analysis is performed of the mid- and low-latitude circulation index at 850 hPa over East Asia, the East Asian monsoon index and the precipitation over the middle and lower reaches of the Yangtze River dur... The wavelet analysis is performed of the mid- and low-latitude circulation index at 850 hPa over East Asia, the East Asian monsoon index and the precipitation over the middle and lower reaches of the Yangtze River during 1998 South China Sea Monsoon Experiment (SCSMEX) from May to August. Analysis shows that distinct 30-60 day low-frequency oscillation (LFO) exists in all of the above elements during the experiment period. Analysis of low-frequency wind field at 850 hPa from May to August with 5 days interval is performed in this Paper. Analysis results reveal that: (l ) A low-frequency monsoon circulation system over East Asia, characterized by distinct 30-60 day low-frequency oscillation, exists over 100°-150°E of East Asian area from the middle and eastern parts of China continent and the South China Sea to the western Pacific in both the Northern and Southern Hemisphere. The activity of East Asian monsoon is mainly affected by the low-frequency systems in it; (2) All of the tropical monsoon onset over the South China Sea in the fifth pentad of May, the beginning of the Meiyu period and heavy rainfall over the middle and lower reaches of the Yangtze River in mid-June and the heavy rainfall after mid-July are related to the activity of low-frequency cyclone belt over the region, whereas the torrential rainfall over the upper reaches of the Yangtze River in August is associated with the westward propagation of low-frequency anticyclone into the mainland; (3) There are two sources of low-frequency oscillation system over East Asia during SCSMEX. i.e. the equatorial South China Sea (SCS) and mid-high latitudes of the middle Pacific in the Northern Hemisphere. The low-frequency system over SCS propagates northward while that in mid-high latitudes mainly propagates from northeast to southwest. Both of the heavy rainfall over the middle and lower reaches of the Yangtze River in June and July are associated with the northward propagation of the above-mentioned SCS low-frequency systems from the tropical region and the southwestward propagation from mid-high latitudes respectively and their convergence in the middle and lower reaches of the Yangtze River; (4) There are two activities of low-frequency cyclone and anticyclone belt each in the East Asian monsoon system during May to August. However the activity of these low-frequency circulation systems is not clearly relevant to the low-frequency circulation system in the indian monsoon system. This means that the low-frequency circulation systems in indian monsoon and East Asian monsoon are independent of each other. The concept previously put forward by Chinese scholars that the East Asian monsoon circulation system (EAMCS) is relatively independent monsoon circulation system is testified once more in the summer 1998. 展开更多
关键词 SCS monsoon onset Flood in the summer 1998 Low-frequency monsoon circulation
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