As emerging services continue to be explored,indoor communications geared towards different user requirements will face severe challenges such as larger penetration losses and more critical multipath issues,leading to...As emerging services continue to be explored,indoor communications geared towards different user requirements will face severe challenges such as larger penetration losses and more critical multipath issues,leading to difficulties in achieving flexible coverage.In this paper,we introduce transmissive reconfigurable intelligent surfaces(RISs)as intelligent passive auxiliary devices into indoor scenes,replacing conventional ultra-dense small cell and relay forwarding approaches to address these issues at low deployment and operation costs.Specifically,we study the optimization design of active and passive beamforming for the transmissive RISs-aided indoor multiuser downlink communication systems.This involves considering more realistic indoor congestion modeling and near-field propagation characteristics.The goal of our optimization is to minimize the total transmit power at the access point(AP)for different user service requirements,including quality-of-service(QoS)and wireless power transfer(WPT).Due to the nonconvex nature of the optimization problem,adaptive penalty coefficients are imported to solve it alternatively with closed-form solutions for both active and passive beamforming.Simulation results demonstrate that the use of transmissive RISs is indeed an efficient way to achieve flexible coverage in indoor scenarios.Furthermore,the proposed optimization algorithm has been proven to be effective and robust in achieving energy-saving transmission.展开更多
Laser speckle contrast imaging(LSCI)is a powerful tool for monitoring blood flow changes in tissue or vessels in vivo,but its applications are limited by shallow penetration depth under reflective imaging configuratio...Laser speckle contrast imaging(LSCI)is a powerful tool for monitoring blood flow changes in tissue or vessels in vivo,but its applications are limited by shallow penetration depth under reflective imaging configuration.The traditional LSCI setup has been used in transmissive imaging for depth extension up to 2l_(t)–3l_(t)(l_(t)is the transport mean free path),but the blood flow estimation is biased due to the depth uncertainty in large depth of field(DOF)images.In this study,we propose a transmissive multifocal LSCI for depth-resolved blood flow in thick tissue,further extending the transmissive LSCI for tissue thickness up to 12lt.The limited-DOF imaging system is applied to the multifocal acquisition,and the depth of the vessel is estimated using a robust visibility parameter V_(r)in the coherent domain.The accuracy and linearity of depth estimation are tested by Monte Carlo simulations.Based on the proposed method,the model of contrast analysis resolving the depth information is established and verified in a phantom experiment.We demonstrated its effectiveness in acquiring depth-resolved vessel structures and flow dynamics in in vivo imaging of chick embryos.展开更多
Coding metasurfaces have attracted tremendous interests due to unique capabilities of manipulating electromagnetic wave.However,archiving transmissive coding metasurface is still challenging.Here we propose a transmis...Coding metasurfaces have attracted tremendous interests due to unique capabilities of manipulating electromagnetic wave.However,archiving transmissive coding metasurface is still challenging.Here we propose a transmissive anisotropic coding metasurface that enables the independent control of two orthogonal polarizations.The polarization beam splitter and the orbital angular momentum(OAM)generator have been studied as typical applications of the anisotropic 2-bit coding metasurface.The simulated far field patterns illustrate that the x and y polarized electromagnetic waves are deflected into two different directions,respectively.The anisotropic coding metasurface has been experimentally verified to realize an OAM beam with l=2 of right-handed polarized wave,resulting from both contributions from linear-to-circular polarization conversion and the phase profile modulation.This work is beneficial to enrich the polarization manipulation field and develop transmissive coding metasurfaces.展开更多
An underwater acoustic metasurface with sub-wavelength thickness is designed for acoustic wavefront manipulation.In this paper,a pentamode lattice and a frequency-independent generalized acoustic Snell's law are i...An underwater acoustic metasurface with sub-wavelength thickness is designed for acoustic wavefront manipulation.In this paper,a pentamode lattice and a frequency-independent generalized acoustic Snell's law are introduced to overcome the limitations of narrow bandwidth and low transmittance.The bulk modulus and effective density of each unit cell can be tuned simultaneously,which are modulated to guarantee the achievement of refractive index profile and high transmission.Here,we actualize anomalous refraction,generation of non-diffracting Bessel beam,sub-wavelength flat focusing,and surface wave conversion by constructing inhomogeneous acoustic metasurface.This design approach has potential applications in medical ultrasound imaging and underwater acoustic communications.展开更多
Objective:This study proposed a transmissive-detected hyperspectral imaging(TD-HSI)strategy for blood oxygen mapping in order to address the limitation of reflective HSI in obtaining high-resolution blood oxygen infor...Objective:This study proposed a transmissive-detected hyperspectral imaging(TD-HSI)strategy for blood oxygen mapping in order to address the limitation of reflective HSI in obtaining high-resolution blood oxygen information from deep tissues.Impact Statement:This innovative TD-HSI has great potential in promoting noninvasive,high-resolution in vivo blood oxygen monitoring and provides a powerful tool for the study of tissue oxygenation and microcirculation diseases.Introduction:Oxygen saturation(SO_(2))served as a critical indicator reflecting physiological states.However,strong scattering of tissue prevents accurate SO_(2) mapping with promising resolution,which also limited the depth of reflective HSI.Methods:Monte Carlo simulations were employed to theoretically evaluate the deeptissue measurement of SO_(2) between conventional reflective-detected HSI(RD-HSI)and TD-HSI.Then,in vivo TD-HSI system was used to observe the impact of hypoxia on individual arteries and veins at various locations in mice,and monitor the SO_(2) fluctuations during subcutaneous tumor growth over a 1-week period.Results:The simulations showed that TD-HSI remarkably extended the depth of accurate SO_(2) detection and boasted approximately 6-fold greater precision in detecting SO_(2) variations.In vivo experiments validated the efficacy of TD-HSI,demonstrating its capability to achieve SO_(2) mapping in mice skin with single-vessel resolution,a feat not possible with RD-HSI.Conclusion:We conducted a comprehensive evaluation of the capability of TD-HSI strategy for deep-tissue blood oxygen imaging.Our data demonstrated that TD-HSI offered substantial improvements over conventional RD-HSI in noninvasively acquiring blood oxygen information in deep tissue.展开更多
Conventional transmissive metasurface design for Internet of things(IoT)communications relies heavily on expert knowledge and iterative full-wave simulations,resulting in high computational cost and limited efficiency...Conventional transmissive metasurface design for Internet of things(IoT)communications relies heavily on expert knowledge and iterative full-wave simulations,resulting in high computational cost and limited efficiency.To address this challenge,we propose an end-to-end deep-learning-based design framework for sub-6 GHz transmissive communication metasurfaces,which enables automatic mapping from target transmission responses to manufacturable physical structures.We first develop a prediction model,Img2S,to accurately estimate the S-parameters of metasurfaces,significantly reducing the need for full-wave simulations.Based on this model,two variational generative networks,strictly constrained-conditional variational autoencoder(SCCVAE)and loosely constrained-conditional variational autoencoder(LC-CVAE),are proposed to synthesize physically realizable metasurface structures by incorporating geometric priors and electromagnetic consistency constraints.Experimental results show that Img2S achieves a mean squared error(MSE)of 9.76×10^(-4)in predicting the simulated S-parameters of metasurfaces over the operating frequency band.Both simulation and measurement results confirm that the generated metasurfaces closely match the target electromagnetic responses,with single-state mean absolute errors(MAEs)below 0.16 in simulation and below 0.31 in measurement,respectively,outperforming conventional design approaches in terms of accuracy and frequency stability while significantly improving the overall design efficiency.展开更多
The state of polarization(SOP)on high-order Poincaréspheres(HOPSs),characterized by their distinctive phase profiles and polarization distributions,plays a crucial role in both classical and quantum optical appli...The state of polarization(SOP)on high-order Poincaréspheres(HOPSs),characterized by their distinctive phase profiles and polarization distributions,plays a crucial role in both classical and quantum optical applications.However,most existing metasurface-based implementations face inherent limitations:passive designs are restricted to represent a few predefined HOPS SOPs,while programmable versions typically constrain to 1-bit or 2-bit phase control resolution.In this paper,dynamic generation of HOPS beams with arbitrary SOP based on a transmissive space-time-coding metasurface is demonstrated.By combining 1-bit phase discretizations via PIN diodes with a time-coding strategy,the metasurface enables quasi-continuous complexamplitude modulation for harmonic waves in both x-and y-polarizations.Based on near-field diffraction theory,arbitrary SOPs on any HOPSm,n can be precisely generated using a linearly polarized basis,which is independently controlled by FPGA reconfiguration.We experimentally demonstrate that polarization holography on HOPS0,0 achieves high polarization purity>91.28%,and vector vortex beams on HOPS1,3 and HOPS−1,3 exhibit high orbital angular momentum mode purities>91.25%.This methodology holds great potential for structured wavefront shaping,vortex generation,and high-capacity planar photonics.展开更多
Orbital angular momentum(OAM)is a phenomenon of vortex phase distribution in free space,which has attracted enormous attention in theoretical research and practical application of wireless communication systems due to...Orbital angular momentum(OAM)is a phenomenon of vortex phase distribution in free space,which has attracted enormous attention in theoretical research and practical application of wireless communication systems due to its characteristic of infinitely orthogonal modes.However,traditional methods generating OAM beams are bound to complex structure,large device,multiple layers,complex feed networks,and limited beams in microwave range.Here,a digital coding transmissive metasurface(DCTMS)with a single layer substrate and the bi-symmetrical arrow is proposed and designed to generate multi-OAM-beam based on Pancharatnam–Berry(PB)phase principle.The 3-bit phase response can be realized by encoding the geometric phase into rotation angle of unit cell for DCTMS.Additionally,the phase compensation of the metasurface is introduced to achieve the beam focusing and the conversion from spherical wave to plane wave.According to the digital convolution theorem,the far-field patterns and near-field distributions of multi-OAM-beam with l=–2 modes are adequately demonstrated by DCTMS prototypes.The OAM efficiency and the purity are calculated to demonstrate the excellent multiOAM-beam.The simulated and experimental results illustrate their performance of OAM beams.The designed DCTMS has profound application in multi-platform wireless communication systems and the multi-channel imaging systems.展开更多
Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization...Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization faces significant obstacles due to the technical challenges of long-distance microwave Wireless Power Transmission(WPT) from geostationary orbit. Even ground-based kilometer-scale WPT experiments remain difficult because of limited testing infrastructure, high costs, and strict electromagnetic wave regulations. Since the 1975 NASA-Raytheon experiment, which successfully recovered 30 kW of power over 1.55 km, there has been little progress in extending the transmission distance or increasing the retrieved power. This study proposes a cost-effective methodology for conducting long-range WPT experiments in constrained environments by utilizing existing infrastructure. A deep space antenna operating at 2.08 GHz with an output power of 2.3 kW and a gain of 55.3 dBi was used as the transmitter. Two test configurations were implemented: a 1.81 km ground-to-air test using an aerostat to elevate the receiver and a 1.82 km ground-to-ground test using a ladder truck positioned on a plateau. The rectenna consists of a lightweight 3×3 patch antenna array(0.9 m × 0.9 m), accompanied by a steering device and LED indicators to verify power reception. The aerostat-based test achieved a power density of 154.6 mW/m2, which corresponds to approximately 6.2% of the theoretical maximum. The performance gap is primarily attributed to near-field interference, detuning of the patch antenna, rectifier mismatch, and alignment issues. These limitations are expected to be mitigated through improved patch antenna fabrication, a transition from GaN to GaAs rectifiers optimized for lower input power, and the implementation of an automated alignment system. With these enhancements, the recovered power is expected to improve by approximately four to five times. The results demonstrate a practical and scalable framework for long-range WPT experiments under constrained conditions and provide key insights for advancing SBSP technology.展开更多
The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor ...The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.展开更多
In this paper,we propose a random access scheme termed sign-compute diversity slotted ALOHA(SCDSA).The SCDSA scheme combines diversity transmission with compute-and-forward.Without considering the capture effect and m...In this paper,we propose a random access scheme termed sign-compute diversity slotted ALOHA(SCDSA).The SCDSA scheme combines diversity transmission with compute-and-forward.Without considering the capture effect and multiple user detection techniques,our scheme can reach a high throughput of 0.98 without feedback under finite frame size settings,where the upper bound on performance is 1.Moreover,a lower bound on throughput performance is derived,which is tight in some parameter settings and can be used to approximate theoretical performance.Simulation results validate our analysis and confirm the advantages of our proposed scheme.展开更多
In this article,we introduce a new theoretical approach to improve the accuracy of twodimensional(2D)atomic localization within a tripod-type,four-level atomic system by analyzing its transmission spectrum.In this met...In this article,we introduce a new theoretical approach to improve the accuracy of twodimensional(2D)atomic localization within a tripod-type,four-level atomic system by analyzing its transmission spectrum.In this method,the atom interacts with two orthogonal standing-wave fields and a weak probe field.By examining how the weak probe field passes through the system,we can determine the atom position.Our analysis reveals the presence of both double and sharply defined single localized peaks in the transmission spectrum,which correspond to specific positions of the atom.Importantly,we achieve ultra-high-resolution atomic localization with accuracy confined to a region smaller thanλ/32×λ/32.This level of precision is a significant improvement compared to earlier methods,which had lower localization accuracy.The increased precision is due to the complex interaction between the atom and the carefully controlled standing-wave and probe fields,which allows for precise control over the atom's position.The implications of this work are significant,especially for applications like nano-lithography,where precise atomic placement is essential,and for laser cooling technologies,where better atomic localization could lead to more effective cooling processes and improved manipulation of atomic states.展开更多
We propose a scheme to achieve nonreciprocal single-photon transmission in a system consisting of a spinning whispering-gallery-mode resonator and a stationary resonator containing a scatterer,both coupled to a one-di...We propose a scheme to achieve nonreciprocal single-photon transmission in a system consisting of a spinning whispering-gallery-mode resonator and a stationary resonator containing a scatterer,both coupled to a one-dimensional waveguide.By tuning the Sagnac-Fizeau shift induced by the spinning resonator,high-contrast nonreciprocal transmission in both forward and backward directions can be realized.Furthermore,we investigate the influences of system parameters including waveguide-resonator coupling strength,inter-mode coupling strengths within two resonators,and inter-cavity coupling strength on nonreciprocal transmissions.The results indicate that the synergistic regulation of these parameters can adjust the position of the nonreciprocal transmission peak and achieve high-contrast nonreciprocal transmission.展开更多
The state-of-the-art optical atomic clocks and the time-frequency signal transmission open a fresh field for gravity potential(geopotential)determination.Various methods,including optical fiber frequency transfer,sate...The state-of-the-art optical atomic clocks and the time-frequency signal transmission open a fresh field for gravity potential(geopotential)determination.Various methods,including optical fiber frequency transfer,satellite two-way,satellite common-view,satellite carrier phase,VLBI,tri-frequency combination,and dual-frequency combination,were developed to determine the geopotential differences using optical atomic clocks and then determine the geopotential at station B based on the geopotential at station A.This review elaborates the principles,methods,scientific objectives,applications,and relevant research trends of geopotential determination based on time-frequency signals.展开更多
Gynandromorphs,rare in vertebrates,exhibit distinct sex-determining gene expression on each side of the body despite sharing a uniform hormonal environment.This provides a unique opportunity to investigate the respect...Gynandromorphs,rare in vertebrates,exhibit distinct sex-determining gene expression on each side of the body despite sharing a uniform hormonal environment.This provides a unique opportunity to investigate the respective roles of genes and hormones in sex determination.We accidently obtained a gynandromorphic Zebra Finch with a male-female chimeric appearance but only with an ovary-like gonad.Its plasma estradiol was significantly higher than that of age-matched females,and its sexual partner preference was also feminine.Although it did not sing like males,its calls showed masculinization.In the brain on one side of the body with male plumage,the area of song motor nucleus,the robust nucleus of the arcopallium(RA),and the excitatory synaptic transmission of RA projection neurons showed masculinization.Transcriptome analysis revealed that genes related to cholinergic neuron function were significantly upregulated in the masculinized side of brain.Moreover,there were extensive and consistent expression differences of neuroactive substance receptor genes in both sides of body,indicating that cell-autonomous determination plays a key role in sex dimorphism of neuromodulation.展开更多
The age-hardening response,mechanical,and corrosion-resistant properties of AA7085 alloys with and without the addition of 0.3 wt.%scandium(Sc)were compared.Using advanced techniques such as aberration-corrected trans...The age-hardening response,mechanical,and corrosion-resistant properties of AA7085 alloys with and without the addition of 0.3 wt.%scandium(Sc)were compared.Using advanced techniques such as aberration-corrected transmission electron microscopy and first-principles calculations,the underlying micromechanisms of Sc microalloying were revealed.Results show that the increase in strength of the AA7085-Sc alloy is mainly attributed to the decreased Al grain size and increased number density of both Al_(3)Sc@Al_(3)(Sc,Zr)core−shell nanoparticles and Sc-containingη_(p) and GP−η_(p) nanoprecipitates.Strong strain fields and evident electron transfer from Zr to the neighboring matrix Al atoms exist at the Al_(3)Sc@Al_(3)(Sc,Zr)/Al interface.The Sc doping in GP−η_(p) andη_(p) suppresses the GP−η_(p)→η_(p) transformation.Modified corrosion resistance of the AA7085-Sc alloy compared with AA7085 alloy is associated with the fine grain boundary precipitates ofη_(p)hases and narrow precipitation free zone.The reasons of property changes of AA7085 alloy after Sc microalloying are explored based on the multiscale microstructural characterization.展开更多
The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfa...The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfaces.A quantitative statistical experimental method was adopted to study the surface⁃contact transmission of micro⁃organisms,wherein the transfer rate of surface contact was the dependent variable and Escherichia coli was used as the indicator bacterium.The effects of contact pressure(0.44,0.86,1.55,2.25,and 2.94 N/cm^(2)),contact time(0,15,30,45,and 60 s),contact angle(15°and 25°),and surface materials(rubber and cotton gloves)were measured at two storage temperatures:cold storage(5℃)and freezing(-18℃).The results showed that as temperature decreases,the transfer of micro⁃organisms through surface contact becomes less probable.The contact time did not significantly influence the transfer rate of micro⁃organisms when items were handled at cold⁃storage temperatures.Based on these results,we recommend placing items as flat as possible to minimize the tilt angle when handling them at cold⁃storage temperatures.Additionally,if the tilt angle cannot be avoided,rubber gloves should be used when handling items stored at large tilt angles,whereas cotton gloves may be used for items placed at smaller angles.展开更多
To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hyb...To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hybrid modular multilevel converter–capacitor-commutated line-commutated converter(MMC-CLCC)HVDC transmission system and its corresponding control strategy.First,the system topology is constructed,and a submodule configuration method for the MMC—combining full-bridge submodules(FBSMs)and half-bridge submodules(HBSMs)—is proposed to enable direct power flow reversal.Second,a hierarchical control strategy is introduced,includingMMCvoltage control,CLCC current control,and a coordinationmechanism,along with the derivation of the hybrid system’s power flow reversal characteristics.Third,leveraging the CLCC’s fast current regulation and theMMC’s negative voltage control capability,a coordinated power flow reversal control strategy is developed.Finally,an 800 kV MMC-CLCC hybrid HVDC system is modeled in PSCAD/EMTDC to validate the power flow reversal performance under a high proportion of full-bridge submodule configuration.Results demonstrate that the proposed control strategy enables rapid(1-s transition)and smooth switching of bidirectional power flow without modifying the structure of primary equipment:the transient fluctuation ofDC voltage from the rated value(UdcN)to themaximumreverse voltage(-kUdcN)is less than 5%;the DC current strictly follows the preset characteristic curve with a deviation of≤3%;the active power reverses continuously,and the system maintains stable operation throughout the reversal process.展开更多
Ultrasound neuromodulation shows promise for treating neurological disorders,but the underlying mechanisms remain unclear.Here,we developed an integrated surface acoustic wave(SAW)ultrasound chip enabling simultaneous...Ultrasound neuromodulation shows promise for treating neurological disorders,but the underlying mechanisms remain unclear.Here,we developed an integrated surface acoustic wave(SAW)ultrasound chip enabling simultaneous electrophysiological recording and Ca^(2+) imaging of cultured hippocampal neurons to investigate neuronal excitability and synaptic transmission during ultrasound stimulation.This study revealed,for the first time,three distinct neuronal response patterns induced by SAW ultrasound:an immediate response showing rapid activation,a delayed response exhibiting facilitation after several minutes,and a non-response maintaining baseline activity.Ultrasound stimulation increased action potential firing,enhanced excitatory postsynaptic currents,and elevated intracellular Ca^(2+) levels.These effects were dependent on extracellular Ca^(2+) influx and primarily dominated by L-type Ca^(2+) channels.Our findings suggest that individual neurons exhibit heterogeneous responses to SAW ultrasound stimulation based on their intracellular Ca^(2+) levels and L-type Ca^(2+) channel activity.This integrated approach provides new insights into the cellular mechanisms of ultrasound neuromodulation while highlighting the potential of SAW technology for precise,cell-type-specific neural control.展开更多
Inspired that kangaroo can buffer the impact and absorb vibration from the ground and keep the whole-body stable,an integrated kangaroo bio-inspired vibration suppression(IKBVS)structure considering vibration isolatio...Inspired that kangaroo can buffer the impact and absorb vibration from the ground and keep the whole-body stable,an integrated kangaroo bio-inspired vibration suppression(IKBVS)structure considering vibration isolation-absorption simultaneously is proposed for low/wide band frequency vibration control.Based on skeleton mass,articulation friction,and the synergistic action among skeleton,articulation,and muscle/tendon,a vibration suppression model with more biological basic characteristics is derived.The validity of model and method is confirmed,and the static and dynamic analysis of the IKBVS system is carried out to investigate the vibration suppression performance.The quasi-zero stiffness region can be achieved with a smaller initial installation angle,medium rod length,smaller foot stiffness,and slightly lighter isolated mass in a wide displacement interval.The coupling mechanism of vibration isolation-absorption is revealed by parameter analysis.The results indicate that the IKBVS structure has favorite dynamic properties due to adjustable nonlinearity,namely,lower and adjustable resonance and anti-resonance frequency/peak and different levels of vibration suppression effect in high-frequency range are achieved readily.This research provides new insight into application of bio-inspired vibration suppression structures in various engineering systems for better vibration control.展开更多
基金supported in part by the Natural Science Basic Research Plan in Shaanxi Province under Grant 2024JC-ZDXM-36in part by the Key Research and Development Program of Shaanxi Province under Grant 2023-YBGY-255+2 种基金in part by the Excellent Youth Science Foundation of Xi’an University of Science and Technology under Grant 2019YQ3-13in part by the Xi’an Key Laboratory of Network Convergence Communications under Grant 2022NCC-K102in part by the Fundamental Research Funds for the Central Universities under Grant QTZX23029。
文摘As emerging services continue to be explored,indoor communications geared towards different user requirements will face severe challenges such as larger penetration losses and more critical multipath issues,leading to difficulties in achieving flexible coverage.In this paper,we introduce transmissive reconfigurable intelligent surfaces(RISs)as intelligent passive auxiliary devices into indoor scenes,replacing conventional ultra-dense small cell and relay forwarding approaches to address these issues at low deployment and operation costs.Specifically,we study the optimization design of active and passive beamforming for the transmissive RISs-aided indoor multiuser downlink communication systems.This involves considering more realistic indoor congestion modeling and near-field propagation characteristics.The goal of our optimization is to minimize the total transmit power at the access point(AP)for different user service requirements,including quality-of-service(QoS)and wireless power transfer(WPT).Due to the nonconvex nature of the optimization problem,adaptive penalty coefficients are imported to solve it alternatively with closed-form solutions for both active and passive beamforming.Simulation results demonstrate that the use of transmissive RISs is indeed an efficient way to achieve flexible coverage in indoor scenarios.Furthermore,the proposed optimization algorithm has been proven to be effective and robust in achieving energy-saving transmission.
基金supported by National Natural Science Foundation of China(NSFC No.61876108)the National Key Research&Development Program of Ministry of Science and Technology of the People's Republic of China(Grant Nos.2018YFC2002300,2018YFC2002303).
文摘Laser speckle contrast imaging(LSCI)is a powerful tool for monitoring blood flow changes in tissue or vessels in vivo,but its applications are limited by shallow penetration depth under reflective imaging configuration.The traditional LSCI setup has been used in transmissive imaging for depth extension up to 2l_(t)–3l_(t)(l_(t)is the transport mean free path),but the blood flow estimation is biased due to the depth uncertainty in large depth of field(DOF)images.In this study,we propose a transmissive multifocal LSCI for depth-resolved blood flow in thick tissue,further extending the transmissive LSCI for tissue thickness up to 12lt.The limited-DOF imaging system is applied to the multifocal acquisition,and the depth of the vessel is estimated using a robust visibility parameter V_(r)in the coherent domain.The accuracy and linearity of depth estimation are tested by Monte Carlo simulations.Based on the proposed method,the model of contrast analysis resolving the depth information is established and verified in a phantom experiment.We demonstrated its effectiveness in acquiring depth-resolved vessel structures and flow dynamics in in vivo imaging of chick embryos.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1931121)the Natural Science Foundation of Heilongjiang Province in China(Grant No.ZD2020F002)+2 种基金111 Project to the Harbin Engineering University(Grant No.B13015)the Fundamental Research Funds for the Central Universities(Grant Nos.3072021CFT2501 and 3072021CF2508)the Postdoctoral Scientific Research Developmental Fund of Heilongjiang Province,China(Grant No.LBH-Q9097).
文摘Coding metasurfaces have attracted tremendous interests due to unique capabilities of manipulating electromagnetic wave.However,archiving transmissive coding metasurface is still challenging.Here we propose a transmissive anisotropic coding metasurface that enables the independent control of two orthogonal polarizations.The polarization beam splitter and the orbital angular momentum(OAM)generator have been studied as typical applications of the anisotropic 2-bit coding metasurface.The simulated far field patterns illustrate that the x and y polarized electromagnetic waves are deflected into two different directions,respectively.The anisotropic coding metasurface has been experimentally verified to realize an OAM beam with l=2 of right-handed polarized wave,resulting from both contributions from linear-to-circular polarization conversion and the phase profile modulation.This work is beneficial to enrich the polarization manipulation field and develop transmissive coding metasurfaces.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61571222 and 11474160)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20161009)the Six-Talent Peaks Project of Jiangsu Province,China
文摘An underwater acoustic metasurface with sub-wavelength thickness is designed for acoustic wavefront manipulation.In this paper,a pentamode lattice and a frequency-independent generalized acoustic Snell's law are introduced to overcome the limitations of narrow bandwidth and low transmittance.The bulk modulus and effective density of each unit cell can be tuned simultaneously,which are modulated to guarantee the achievement of refractive index profile and high transmission.Here,we actualize anomalous refraction,generation of non-diffracting Bessel beam,sub-wavelength flat focusing,and surface wave conversion by constructing inhomogeneous acoustic metasurface.This design approach has potential applications in medical ultrasound imaging and underwater acoustic communications.
基金supported by the National Natural Science Foundation of China(grant nos.62375096,82361138569,32361133552,and 62375095)the National Key R&D Program of China(no.2025YFF1500200)+3 种基金the Natural Science Foundation of Wuhan(no.2024040801020204)the Interdisciplinary Research Program of HUST(no.2024JCYJ064)the Open Competition Project of Wuhan East Lake High-tech Development Zone(no.2023KJB224)the Innovation Project of Optics Valley Laboratory(grant no.OVL2025BB008).
文摘Objective:This study proposed a transmissive-detected hyperspectral imaging(TD-HSI)strategy for blood oxygen mapping in order to address the limitation of reflective HSI in obtaining high-resolution blood oxygen information from deep tissues.Impact Statement:This innovative TD-HSI has great potential in promoting noninvasive,high-resolution in vivo blood oxygen monitoring and provides a powerful tool for the study of tissue oxygenation and microcirculation diseases.Introduction:Oxygen saturation(SO_(2))served as a critical indicator reflecting physiological states.However,strong scattering of tissue prevents accurate SO_(2) mapping with promising resolution,which also limited the depth of reflective HSI.Methods:Monte Carlo simulations were employed to theoretically evaluate the deeptissue measurement of SO_(2) between conventional reflective-detected HSI(RD-HSI)and TD-HSI.Then,in vivo TD-HSI system was used to observe the impact of hypoxia on individual arteries and veins at various locations in mice,and monitor the SO_(2) fluctuations during subcutaneous tumor growth over a 1-week period.Results:The simulations showed that TD-HSI remarkably extended the depth of accurate SO_(2) detection and boasted approximately 6-fold greater precision in detecting SO_(2) variations.In vivo experiments validated the efficacy of TD-HSI,demonstrating its capability to achieve SO_(2) mapping in mice skin with single-vessel resolution,a feat not possible with RD-HSI.Conclusion:We conducted a comprehensive evaluation of the capability of TD-HSI strategy for deep-tissue blood oxygen imaging.Our data demonstrated that TD-HSI offered substantial improvements over conventional RD-HSI in noninvasively acquiring blood oxygen information in deep tissue.
基金supported by the National Natural Science Foundation of China under Grant 92567202。
文摘Conventional transmissive metasurface design for Internet of things(IoT)communications relies heavily on expert knowledge and iterative full-wave simulations,resulting in high computational cost and limited efficiency.To address this challenge,we propose an end-to-end deep-learning-based design framework for sub-6 GHz transmissive communication metasurfaces,which enables automatic mapping from target transmission responses to manufacturable physical structures.We first develop a prediction model,Img2S,to accurately estimate the S-parameters of metasurfaces,significantly reducing the need for full-wave simulations.Based on this model,two variational generative networks,strictly constrained-conditional variational autoencoder(SCCVAE)and loosely constrained-conditional variational autoencoder(LC-CVAE),are proposed to synthesize physically realizable metasurface structures by incorporating geometric priors and electromagnetic consistency constraints.Experimental results show that Img2S achieves a mean squared error(MSE)of 9.76×10^(-4)in predicting the simulated S-parameters of metasurfaces over the operating frequency band.Both simulation and measurement results confirm that the generated metasurfaces closely match the target electromagnetic responses,with single-state mean absolute errors(MAEs)below 0.16 in simulation and below 0.31 in measurement,respectively,outperforming conventional design approaches in terms of accuracy and frequency stability while significantly improving the overall design efficiency.
基金National Natural Science Foundation of China(62271056,62171186,62201037)Technology Innovation Center of Infrared Remote Sensing Metrology Technology of State Administration for Market Regulation(AKYKF2423)+5 种基金National Key Research and Development Program of China(2022YFF0604801)Beijing Natural Science Foundation Haidian Original Innovation Joint Fund(L222042)Open Research Fund of State Key Laboratory of Millimeter Waves(K202326)Open Research Fund of State Key Laboratory of Space-Ground Integrated Information Technology(6142221200201)Basic Research Foundation of Beijing Institute of Technology,China(BITBLR2020014)111 Project of China(B14010).
文摘The state of polarization(SOP)on high-order Poincaréspheres(HOPSs),characterized by their distinctive phase profiles and polarization distributions,plays a crucial role in both classical and quantum optical applications.However,most existing metasurface-based implementations face inherent limitations:passive designs are restricted to represent a few predefined HOPS SOPs,while programmable versions typically constrain to 1-bit or 2-bit phase control resolution.In this paper,dynamic generation of HOPS beams with arbitrary SOP based on a transmissive space-time-coding metasurface is demonstrated.By combining 1-bit phase discretizations via PIN diodes with a time-coding strategy,the metasurface enables quasi-continuous complexamplitude modulation for harmonic waves in both x-and y-polarizations.Based on near-field diffraction theory,arbitrary SOPs on any HOPSm,n can be precisely generated using a linearly polarized basis,which is independently controlled by FPGA reconfiguration.We experimentally demonstrate that polarization holography on HOPS0,0 achieves high polarization purity>91.28%,and vector vortex beams on HOPS1,3 and HOPS−1,3 exhibit high orbital angular momentum mode purities>91.25%.This methodology holds great potential for structured wavefront shaping,vortex generation,and high-capacity planar photonics.
基金supported by the National Natural Science Foundation of China(Grant Nos.62171460 and 61801508)the Natural Science Basic Research Program of Shaanxi Province,China(Grant Nos.2020JM-350,20200108,and 20210110)+3 种基金the Young Innovation Team at Colleges of Shaanxi Province,China(Grant No.2020022)the Postdoctoral Innovative Talents Support Program of China(Grant No.BX20180375)China Postdoctoral Science Foundation(Grant Nos.2021T140111,2019M650098,and 2019M653960)the Postdoctoral Research Funding of Jiangsu Province(No.2019K219).
文摘Orbital angular momentum(OAM)is a phenomenon of vortex phase distribution in free space,which has attracted enormous attention in theoretical research and practical application of wireless communication systems due to its characteristic of infinitely orthogonal modes.However,traditional methods generating OAM beams are bound to complex structure,large device,multiple layers,complex feed networks,and limited beams in microwave range.Here,a digital coding transmissive metasurface(DCTMS)with a single layer substrate and the bi-symmetrical arrow is proposed and designed to generate multi-OAM-beam based on Pancharatnam–Berry(PB)phase principle.The 3-bit phase response can be realized by encoding the geometric phase into rotation angle of unit cell for DCTMS.Additionally,the phase compensation of the metasurface is introduced to achieve the beam focusing and the conversion from spherical wave to plane wave.According to the digital convolution theorem,the far-field patterns and near-field distributions of multi-OAM-beam with l=–2 modes are adequately demonstrated by DCTMS prototypes.The OAM efficiency and the purity are calculated to demonstrate the excellent multiOAM-beam.The simulated and experimental results illustrate their performance of OAM beams.The designed DCTMS has profound application in multi-platform wireless communication systems and the multi-channel imaging systems.
文摘Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization faces significant obstacles due to the technical challenges of long-distance microwave Wireless Power Transmission(WPT) from geostationary orbit. Even ground-based kilometer-scale WPT experiments remain difficult because of limited testing infrastructure, high costs, and strict electromagnetic wave regulations. Since the 1975 NASA-Raytheon experiment, which successfully recovered 30 kW of power over 1.55 km, there has been little progress in extending the transmission distance or increasing the retrieved power. This study proposes a cost-effective methodology for conducting long-range WPT experiments in constrained environments by utilizing existing infrastructure. A deep space antenna operating at 2.08 GHz with an output power of 2.3 kW and a gain of 55.3 dBi was used as the transmitter. Two test configurations were implemented: a 1.81 km ground-to-air test using an aerostat to elevate the receiver and a 1.82 km ground-to-ground test using a ladder truck positioned on a plateau. The rectenna consists of a lightweight 3×3 patch antenna array(0.9 m × 0.9 m), accompanied by a steering device and LED indicators to verify power reception. The aerostat-based test achieved a power density of 154.6 mW/m2, which corresponds to approximately 6.2% of the theoretical maximum. The performance gap is primarily attributed to near-field interference, detuning of the patch antenna, rectifier mismatch, and alignment issues. These limitations are expected to be mitigated through improved patch antenna fabrication, a transition from GaN to GaAs rectifiers optimized for lower input power, and the implementation of an automated alignment system. With these enhancements, the recovered power is expected to improve by approximately four to five times. The results demonstrate a practical and scalable framework for long-range WPT experiments under constrained conditions and provide key insights for advancing SBSP technology.
文摘The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.
文摘In this paper,we propose a random access scheme termed sign-compute diversity slotted ALOHA(SCDSA).The SCDSA scheme combines diversity transmission with compute-and-forward.Without considering the capture effect and multiple user detection techniques,our scheme can reach a high throughput of 0.98 without feedback under finite frame size settings,where the upper bound on performance is 1.Moreover,a lower bound on throughput performance is derived,which is tight in some parameter settings and can be used to approximate theoretical performance.Simulation results validate our analysis and confirm the advantages of our proposed scheme.
基金Princess Nourah bint Abdulrahman University Researchers Supporting Project number(PNURSP2025R8)。
文摘In this article,we introduce a new theoretical approach to improve the accuracy of twodimensional(2D)atomic localization within a tripod-type,four-level atomic system by analyzing its transmission spectrum.In this method,the atom interacts with two orthogonal standing-wave fields and a weak probe field.By examining how the weak probe field passes through the system,we can determine the atom position.Our analysis reveals the presence of both double and sharply defined single localized peaks in the transmission spectrum,which correspond to specific positions of the atom.Importantly,we achieve ultra-high-resolution atomic localization with accuracy confined to a region smaller thanλ/32×λ/32.This level of precision is a significant improvement compared to earlier methods,which had lower localization accuracy.The increased precision is due to the complex interaction between the atom and the carefully controlled standing-wave and probe fields,which allows for precise control over the atom's position.The implications of this work are significant,especially for applications like nano-lithography,where precise atomic placement is essential,and for laser cooling technologies,where better atomic localization could lead to more effective cooling processes and improved manipulation of atomic states.
基金financially supported by the National Natural Science Foundation of China(12064045)。
文摘We propose a scheme to achieve nonreciprocal single-photon transmission in a system consisting of a spinning whispering-gallery-mode resonator and a stationary resonator containing a scatterer,both coupled to a one-dimensional waveguide.By tuning the Sagnac-Fizeau shift induced by the spinning resonator,high-contrast nonreciprocal transmission in both forward and backward directions can be realized.Furthermore,we investigate the influences of system parameters including waveguide-resonator coupling strength,inter-mode coupling strengths within two resonators,and inter-cavity coupling strength on nonreciprocal transmissions.The results indicate that the synergistic regulation of these parameters can adjust the position of the nonreciprocal transmission peak and achieve high-contrast nonreciprocal transmission.
基金National Natural Science Foundation of China(Grant Nos.42388102,42030105,42192535)the Open Fund of State Key Laboratory of Precision Geodesy,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences(Grant No.SKLPG2025-1-5)。
文摘The state-of-the-art optical atomic clocks and the time-frequency signal transmission open a fresh field for gravity potential(geopotential)determination.Various methods,including optical fiber frequency transfer,satellite two-way,satellite common-view,satellite carrier phase,VLBI,tri-frequency combination,and dual-frequency combination,were developed to determine the geopotential differences using optical atomic clocks and then determine the geopotential at station B based on the geopotential at station A.This review elaborates the principles,methods,scientific objectives,applications,and relevant research trends of geopotential determination based on time-frequency signals.
基金funded by the National Natural Science Foundation of China(32160123 and 32170974)Jiangxi Provincial Key Project of Natural Science Foundation(20212ACB205002)Jiangxi Provincial Key Laboratory of Organic Functional Molecules(2024SSY05141)。
文摘Gynandromorphs,rare in vertebrates,exhibit distinct sex-determining gene expression on each side of the body despite sharing a uniform hormonal environment.This provides a unique opportunity to investigate the respective roles of genes and hormones in sex determination.We accidently obtained a gynandromorphic Zebra Finch with a male-female chimeric appearance but only with an ovary-like gonad.Its plasma estradiol was significantly higher than that of age-matched females,and its sexual partner preference was also feminine.Although it did not sing like males,its calls showed masculinization.In the brain on one side of the body with male plumage,the area of song motor nucleus,the robust nucleus of the arcopallium(RA),and the excitatory synaptic transmission of RA projection neurons showed masculinization.Transcriptome analysis revealed that genes related to cholinergic neuron function were significantly upregulated in the masculinized side of brain.Moreover,there were extensive and consistent expression differences of neuroactive substance receptor genes in both sides of body,indicating that cell-autonomous determination plays a key role in sex dimorphism of neuromodulation.
基金the support from the National Natural Science Foundation of China (Nos. U20A20274, 52061003)the Natural Science Foundation of Yunnan Province, China (No. 202301AT070209)the Science and Technology Major Project of Yunnan Province, China (No. 202102AG050017)。
文摘The age-hardening response,mechanical,and corrosion-resistant properties of AA7085 alloys with and without the addition of 0.3 wt.%scandium(Sc)were compared.Using advanced techniques such as aberration-corrected transmission electron microscopy and first-principles calculations,the underlying micromechanisms of Sc microalloying were revealed.Results show that the increase in strength of the AA7085-Sc alloy is mainly attributed to the decreased Al grain size and increased number density of both Al_(3)Sc@Al_(3)(Sc,Zr)core−shell nanoparticles and Sc-containingη_(p) and GP−η_(p) nanoprecipitates.Strong strain fields and evident electron transfer from Zr to the neighboring matrix Al atoms exist at the Al_(3)Sc@Al_(3)(Sc,Zr)/Al interface.The Sc doping in GP−η_(p) andη_(p) suppresses the GP−η_(p)→η_(p) transformation.Modified corrosion resistance of the AA7085-Sc alloy compared with AA7085 alloy is associated with the fine grain boundary precipitates ofη_(p)hases and narrow precipitation free zone.The reasons of property changes of AA7085 alloy after Sc microalloying are explored based on the multiscale microstructural characterization.
基金National Natural Science Foundation of China(Grant No.52278121).
文摘The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfaces.A quantitative statistical experimental method was adopted to study the surface⁃contact transmission of micro⁃organisms,wherein the transfer rate of surface contact was the dependent variable and Escherichia coli was used as the indicator bacterium.The effects of contact pressure(0.44,0.86,1.55,2.25,and 2.94 N/cm^(2)),contact time(0,15,30,45,and 60 s),contact angle(15°and 25°),and surface materials(rubber and cotton gloves)were measured at two storage temperatures:cold storage(5℃)and freezing(-18℃).The results showed that as temperature decreases,the transfer of micro⁃organisms through surface contact becomes less probable.The contact time did not significantly influence the transfer rate of micro⁃organisms when items were handled at cold⁃storage temperatures.Based on these results,we recommend placing items as flat as possible to minimize the tilt angle when handling them at cold⁃storage temperatures.Additionally,if the tilt angle cannot be avoided,rubber gloves should be used when handling items stored at large tilt angles,whereas cotton gloves may be used for items placed at smaller angles.
基金supported by Science and Technology Project of the headquarters of the State Grid Corporation of China(No.5500-202324492A-3-2-ZN).
文摘To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hybrid modular multilevel converter–capacitor-commutated line-commutated converter(MMC-CLCC)HVDC transmission system and its corresponding control strategy.First,the system topology is constructed,and a submodule configuration method for the MMC—combining full-bridge submodules(FBSMs)and half-bridge submodules(HBSMs)—is proposed to enable direct power flow reversal.Second,a hierarchical control strategy is introduced,includingMMCvoltage control,CLCC current control,and a coordinationmechanism,along with the derivation of the hybrid system’s power flow reversal characteristics.Third,leveraging the CLCC’s fast current regulation and theMMC’s negative voltage control capability,a coordinated power flow reversal control strategy is developed.Finally,an 800 kV MMC-CLCC hybrid HVDC system is modeled in PSCAD/EMTDC to validate the power flow reversal performance under a high proportion of full-bridge submodule configuration.Results demonstrate that the proposed control strategy enables rapid(1-s transition)and smooth switching of bidirectional power flow without modifying the structure of primary equipment:the transient fluctuation ofDC voltage from the rated value(UdcN)to themaximumreverse voltage(-kUdcN)is less than 5%;the DC current strictly follows the preset characteristic curve with a deviation of≤3%;the active power reverses continuously,and the system maintains stable operation throughout the reversal process.
基金supported by the National Key Research&Development Program of China(2022YFC3602700,2022YFC3602702)the Science and Technology Innovation 2030-Brain Science and Brain-Inspired Intelligence Project(2021ZD0201301)+2 种基金the National Natural Science Foundation of China(12034015,62088101,32170688,323B1004)Program of Shanghai Academic Research Leader(21XD1403600)Shanghai Municipal Science and Technology Major Project(2021SHZDZX0100,2018SHZDZX01).
文摘Ultrasound neuromodulation shows promise for treating neurological disorders,but the underlying mechanisms remain unclear.Here,we developed an integrated surface acoustic wave(SAW)ultrasound chip enabling simultaneous electrophysiological recording and Ca^(2+) imaging of cultured hippocampal neurons to investigate neuronal excitability and synaptic transmission during ultrasound stimulation.This study revealed,for the first time,three distinct neuronal response patterns induced by SAW ultrasound:an immediate response showing rapid activation,a delayed response exhibiting facilitation after several minutes,and a non-response maintaining baseline activity.Ultrasound stimulation increased action potential firing,enhanced excitatory postsynaptic currents,and elevated intracellular Ca^(2+) levels.These effects were dependent on extracellular Ca^(2+) influx and primarily dominated by L-type Ca^(2+) channels.Our findings suggest that individual neurons exhibit heterogeneous responses to SAW ultrasound stimulation based on their intracellular Ca^(2+) levels and L-type Ca^(2+) channel activity.This integrated approach provides new insights into the cellular mechanisms of ultrasound neuromodulation while highlighting the potential of SAW technology for precise,cell-type-specific neural control.
基金supported by the Natural Science Foundation of China(Grant No.52275091)Natural Science Foundation of Liaoning Province(Grant No.2022-MS-125)+1 种基金Shenyang Natural Science Foundation(Grant No.23-503-6-02)Fundamental Research Funds for the Central Universities(Grant No.N2303011).
文摘Inspired that kangaroo can buffer the impact and absorb vibration from the ground and keep the whole-body stable,an integrated kangaroo bio-inspired vibration suppression(IKBVS)structure considering vibration isolation-absorption simultaneously is proposed for low/wide band frequency vibration control.Based on skeleton mass,articulation friction,and the synergistic action among skeleton,articulation,and muscle/tendon,a vibration suppression model with more biological basic characteristics is derived.The validity of model and method is confirmed,and the static and dynamic analysis of the IKBVS system is carried out to investigate the vibration suppression performance.The quasi-zero stiffness region can be achieved with a smaller initial installation angle,medium rod length,smaller foot stiffness,and slightly lighter isolated mass in a wide displacement interval.The coupling mechanism of vibration isolation-absorption is revealed by parameter analysis.The results indicate that the IKBVS structure has favorite dynamic properties due to adjustable nonlinearity,namely,lower and adjustable resonance and anti-resonance frequency/peak and different levels of vibration suppression effect in high-frequency range are achieved readily.This research provides new insight into application of bio-inspired vibration suppression structures in various engineering systems for better vibration control.
