The variation of the nonlinear contact stiffness induced by the elastic wheel-holding effect between the aircraft and tractor has an important effect on the vibration characteristics of an airfield towbarless traction...The variation of the nonlinear contact stiffness induced by the elastic wheel-holding effect between the aircraft and tractor has an important effect on the vibration characteristics of an airfield towbarless traction system,making it essential for ensuring the safety of this emerging towing-out mode.In this paper,the frequency evolutionary tendency of the traction system is studied and obtained considering the variation of nonlinear contact stiffness for the first time.A novel modal analysis method,based on a derived nonlinear contact relationship,is proposed to investigate the vibration characteristics for mechanical system.Frequency veering and mode exchange phenomena in the low-order modes are observed due to the variation of nonlinear contact stiffness.These findings are further validated by the experimental results of a scaled-down model.In addition,it is also found that the veering critical point will be shifted with the external loads.The study provides valuable insights into the vibration characteristics and frequency veering behavior of similar mechanism-based systems,such as towbarless traction system,and has important implications for improving their design and operational performance.展开更多
Metamaterials with multistability have attracted much attention due to their extraordinary physical properties. In this paper, we report a novel multistable strategy that is reversible under external forces, based on ...Metamaterials with multistability have attracted much attention due to their extraordinary physical properties. In this paper, we report a novel multistable strategy that is reversible under external forces, based on the fact that a variational reversible locally resonant elastic metamaterial(LREM) with four configurations is proposed. Through a combination of theoretical analysis and numerical simulations, this newly designed metamaterial is proven to exhibit different bandgap ranges and vibration attenuation properties in each configuration. Especially, there is tunable anisotropy shown in these configurations, which enables the bandgaps in two directions to be separated or overlapped. A model with a bandgap shifting ratio(BSR) of 100% and an overlap ratio of 25% is set to validate the multistable strategy feasibility. The proposed design strategy demonstrates significant potentials for applications in versatile scenarios.展开更多
In this work,we design a twisting metamaterial for longitudinal-torsional(L-T)mode conversion in pipes through exploring the theory of perfect transmodal FabryPerot interference(TFPI).Assuming that the axial and radia...In this work,we design a twisting metamaterial for longitudinal-torsional(L-T)mode conversion in pipes through exploring the theory of perfect transmodal FabryPerot interference(TFPI).Assuming that the axial and radial motions in pipes can be decoupled,we find that the metamaterial can be designed in a rectangular coordinate system,which is much more convenient than that in a cylindrical system.Numerical calculation with detailed microstructures shows that an efficient L-T mode conversion can be obtained in pipes with different radii.In addition,we fabricate mode-converting microstructures on an aluminum pipe and conduct ultrasonic experiments,and the results are in good agreement with the numerical calculations.We expect that the proposed LT mode-converting metamaterial and its design methodology can be applied in various ultrasonic devices.展开更多
To adapt to the multi-scale and multi-dimensional communication scenarios in 6G wireless communications,photon-assisted terahertz(THz)technology has attracted widespread attention due to its low latency and high direc...To adapt to the multi-scale and multi-dimensional communication scenarios in 6G wireless communications,photon-assisted terahertz(THz)technology has attracted widespread attention due to its low latency and high directivity,which maximizes the broadband and high-frequency response characteristics of optical devices and effectively breaks through the capacity limitation of electronic THz technology[1,2].However,THz wireless communications face the problem of weak THz wave penetration and large path loss caused by strong atmospheric attenuation,which limits the coverage of THz signals[3,4].Therefore,multiple-input multiple-output(MIMO)technology has been introduced in the THz system by using antenna arrays at both the transmitter and the receiver to improve the quality of THz links and increase the capacity of wireless networks[5-7].展开更多
In the advancement toward achieving seamless global coverage across space-air-ground-sea in sixth-generation(6G)mobile networks,emerging applications such as low Earth orbit(LEO)satellite constellations,highaltitude p...In the advancement toward achieving seamless global coverage across space-air-ground-sea in sixth-generation(6G)mobile networks,emerging applications such as low Earth orbit(LEO)satellite constellations,highaltitude platform stations(HAPS),and dynamically relayed unmanned aerial vehicle(UAV)networks have created an urgent demand for wireless technologies that simultaneously support ultra-high data rates and ultralong-distance transmission.展开更多
Terahertz(THz)wireless transmission has been extensively researched and utilized to meet the growing need for large-capacity and long-distance wireless communication services[1].For THz band(0.3-10 THz)communication,m...Terahertz(THz)wireless transmission has been extensively researched and utilized to meet the growing need for large-capacity and long-distance wireless communication services[1].For THz band(0.3-10 THz)communication,most reported photonics THz wireless communication demonstrations have a distance of less than 1 km,with most not exceeding 100meters or even 1 meter[1-9].The reported high-speed THz delivery results are realized based on heterodyne detection with complex architecture[1-7].展开更多
We experimentally demonstrate the transmission of discrete multi-tone(DMT)millimeter-wave(mm-wave)signals over a 1.2-km distance at the D-band(110–170 GHz)in a cost-effective intensity-modulation and direct-detection...We experimentally demonstrate the transmission of discrete multi-tone(DMT)millimeter-wave(mm-wave)signals over a 1.2-km distance at the D-band(110–170 GHz)in a cost-effective intensity-modulation and direct-detection(IM/DD)communication system.In the experiment,we successfully achieve the transmission of DMT-QPSK and DMT-16QAM mm-wave signals over multiple-input multiple-output(MIMO)links.After the 1.2-km free-space transmission,the bit error rate(BER)of the DMT-16QAM is below the 25%soft decision forward error correction(25%SD-FEC)threshold of 4×10^(-2),with a maximum net bit rate of 24.62 Gbit/s achieved in this system.展开更多
In recent years,free space optical communication(FSO)has been a hot topic in satellite-to-ground communications,inter-satellite communications,and wireless access networks[1-4].It has the advantages of rich spectrum r...In recent years,free space optical communication(FSO)has been a hot topic in satellite-to-ground communications,inter-satellite communications,and wireless access networks[1-4].It has the advantages of rich spectrum resources,no need for spectrum authorization,high spectrum efficiency verified by experiments,narrow beam angle,and low space loss under good weather.In point-to-point communications,the beam angle makes the FSO almost immune to multipath effects,and low-complexity Digital Signal Processing(DSP)algorithms can be used for recovery demodulation.展开更多
Due to the rise of innovative technologies like artificial intelligence(AI),the Internet of Things(IoT),and telemedicine,the demand for internet traffic is rapidly increasing.In order to achieve ultra-high-speed wirel...Due to the rise of innovative technologies like artificial intelligence(AI),the Internet of Things(IoT),and telemedicine,the demand for internet traffic is rapidly increasing.In order to achieve ultra-high-speed wireless communication,many researchers are directing their efforts towards the Dband.The D-band,spanning the frequency band 110-170 GHz,has abundant spectrum resources and license-free characteristics[1,2].展开更多
Carbon capture,utilization and storage(CCUS)technologies play an essential role in achieving Net Zero Emissions targets.Considering the lack of timely reviews on the recent advancements in promising CCUS technologies,...Carbon capture,utilization and storage(CCUS)technologies play an essential role in achieving Net Zero Emissions targets.Considering the lack of timely reviews on the recent advancements in promising CCUS technologies,it is crucial to provide a prompt review of the CCUS advances to understand the current research gaps pertained to its industrial application.To that end,this review first summarized the developmental history of CCUS technologies and the current large-scale demonstrations.Then,based on a visually bibliometric analysis,the carbon capture remains a hotspot in the CCUS development.Noting that the materials applied in the carbon capture process determines its performance.As a result,the state-of-the-art carbon capture materials and emerging capture technologies were comprehensively summarized and discussed.Gaps between state-of-art carbon capture process and its ideal counterpart are analyzed,and insights into the research needs such as material design,process optimization,environmental impact,and technical and economic assessments are provided.展开更多
This study presents a two-dimensional phononic crystal with heat flux manipulation and wide bandgaps of out-of-plane modes within the low-frequency range. The anisotropic matrix made of spiral-multilayered materials w...This study presents a two-dimensional phononic crystal with heat flux manipulation and wide bandgaps of out-of-plane modes within the low-frequency range. The anisotropic matrix made of spiral-multilayered materials with different thermal conductivities, and the coating layer inserted with metal are designed for heat flux manipulation. Rubber-coated metal cylinders are periodically embedded in the anisotropic matrix to obtain the low-frequency bandgaps of out-of-plane modes. Numerical simulation is carried out to validate the heat and elastic characteristics of the spiral-multilayered anisotropic structure and reveal the effects of the laying angle and temperature on the bandgaps. Subsequently, a spiral-multilayered plate with periodic structures is studied, which shows an obvious vibration attenuation in the frequency ranges of the bandgaps and a deflected heat flux from the initial propagation direction. In the experimental investigation, the multi-phase spiral-multilayered anisotropic plate is simplified to a single-phase anisotropic plate made of aluminum. The characteristics of this type of anisotropic phononic crystal structure may pave the way for the design of a new kind of thermo-acoustic metamaterial serving in combined thermal and acoustic environments.展开更多
The International Telecommunication Union(ITU)has introduced the concept of“intelligent connectivity for 2030”,which is driving the development of 6G technology.This next-generation wireless network is finding appli...The International Telecommunication Union(ITU)has introduced the concept of“intelligent connectivity for 2030”,which is driving the development of 6G technology.This next-generation wireless network is finding applications across various sectors,including smart cities,autonomous driving,holographic imaging,and satellite communications.When compared to 5G,the demands for higher data transmission rates,lower latency,and more efficient use of spectrum have become even more critical.展开更多
In this paper,optoelectronic technology is used to effectively utilize bandwidth resources in the band of 110-170 GHz,thereby increasing system capacity.We use the flexible control characteristics of the operating fre...In this paper,optoelectronic technology is used to effectively utilize bandwidth resources in the band of 110-170 GHz,thereby increasing system capacity.We use the flexible control characteristics of the operating frequency of optoelectronic technology,and large-scale frequency hopping communications are realized to avoid potential interference.We have achieved 24 Gbps full-band sub-THz transmission over 4.6 km within the continuous range of 110-170 GHz in the dense fog simulation environment based on advanced optoelectronic technology,and the carrier frequency is continuously adjustable with an accuracy value of less than 0.2%.In the continuous range of 125-155 GHz,demonstrations of full-band 40 Gbps over 4.6 km are reported.Our work is of reference significance for high-speed long-haul sub-THz band communications under stringent conditions.展开更多
基金co-supported by the Key Projects of the Civil Aviation Joint Fund of the National Natural Science Foundation of China(No.U2033208)。
文摘The variation of the nonlinear contact stiffness induced by the elastic wheel-holding effect between the aircraft and tractor has an important effect on the vibration characteristics of an airfield towbarless traction system,making it essential for ensuring the safety of this emerging towing-out mode.In this paper,the frequency evolutionary tendency of the traction system is studied and obtained considering the variation of nonlinear contact stiffness for the first time.A novel modal analysis method,based on a derived nonlinear contact relationship,is proposed to investigate the vibration characteristics for mechanical system.Frequency veering and mode exchange phenomena in the low-order modes are observed due to the variation of nonlinear contact stiffness.These findings are further validated by the experimental results of a scaled-down model.In addition,it is also found that the veering critical point will be shifted with the external loads.The study provides valuable insights into the vibration characteristics and frequency veering behavior of similar mechanism-based systems,such as towbarless traction system,and has important implications for improving their design and operational performance.
基金supported by the National Natural Science Foundation of China(No.52192633)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2025JC-YBMS-050)。
文摘Metamaterials with multistability have attracted much attention due to their extraordinary physical properties. In this paper, we report a novel multistable strategy that is reversible under external forces, based on the fact that a variational reversible locally resonant elastic metamaterial(LREM) with four configurations is proposed. Through a combination of theoretical analysis and numerical simulations, this newly designed metamaterial is proven to exhibit different bandgap ranges and vibration attenuation properties in each configuration. Especially, there is tunable anisotropy shown in these configurations, which enables the bandgaps in two directions to be separated or overlapped. A model with a bandgap shifting ratio(BSR) of 100% and an overlap ratio of 25% is set to validate the multistable strategy feasibility. The proposed design strategy demonstrates significant potentials for applications in versatile scenarios.
基金Project supported by the National Natural Science Foundation of China(Nos.U2033208,52192633)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2021JQ-006)+1 种基金the China Postdoctoral Science Foundation(No.2020TQ0241)the Innovative Scientific Program of China Nuclear Power Engineering Co.,Ltd。
文摘In this work,we design a twisting metamaterial for longitudinal-torsional(L-T)mode conversion in pipes through exploring the theory of perfect transmodal FabryPerot interference(TFPI).Assuming that the axial and radial motions in pipes can be decoupled,we find that the metamaterial can be designed in a rectangular coordinate system,which is much more convenient than that in a cylindrical system.Numerical calculation with detailed microstructures shows that an efficient L-T mode conversion can be obtained in pipes with different radii.In addition,we fabricate mode-converting microstructures on an aluminum pipe and conduct ultrasonic experiments,and the results are in good agreement with the numerical calculations.We expect that the proposed LT mode-converting metamaterial and its design methodology can be applied in various ultrasonic devices.
基金supported by the National Key R&D Program of China(Grant No.2023YFB2905600)the National Natural Science Foundation of China(Grant Nos.62127802,62331004,62305067,U24B20142,U24B20168,62427815)the Key Project of Jiangsu Province of China(Grant No.BE2023001-4).
文摘To adapt to the multi-scale and multi-dimensional communication scenarios in 6G wireless communications,photon-assisted terahertz(THz)technology has attracted widespread attention due to its low latency and high directivity,which maximizes the broadband and high-frequency response characteristics of optical devices and effectively breaks through the capacity limitation of electronic THz technology[1,2].However,THz wireless communications face the problem of weak THz wave penetration and large path loss caused by strong atmospheric attenuation,which limits the coverage of THz signals[3,4].Therefore,multiple-input multiple-output(MIMO)technology has been introduced in the THz system by using antenna arrays at both the transmitter and the receiver to improve the quality of THz links and increase the capacity of wireless networks[5-7].
基金supported by the National Key R&D Program of China(Grant No.2023YFB2905600)the National Natural Science Foundation of China(Grant Nos.62127802,62331004,62305067,U24B20142,U24B20168,62427815)the Key Project of Jiangsu Province of China(Grant No.BE2023001-4)。
文摘In the advancement toward achieving seamless global coverage across space-air-ground-sea in sixth-generation(6G)mobile networks,emerging applications such as low Earth orbit(LEO)satellite constellations,highaltitude platform stations(HAPS),and dynamically relayed unmanned aerial vehicle(UAV)networks have created an urgent demand for wireless technologies that simultaneously support ultra-high data rates and ultralong-distance transmission.
基金supported by the National Natural Science Foundation of China(Grant Nos.61935005,61835002,62305067,62375219 and 62331004)the Natural Science Foundation of Shaanxi Province(Grant No.2023-JC-JQ-58)Innovation Capability Support Program of Shaanxi(Grant No.2021TD-09)。
文摘Terahertz(THz)wireless transmission has been extensively researched and utilized to meet the growing need for large-capacity and long-distance wireless communication services[1].For THz band(0.3-10 THz)communication,most reported photonics THz wireless communication demonstrations have a distance of less than 1 km,with most not exceeding 100meters or even 1 meter[1-9].The reported high-speed THz delivery results are realized based on heterodyne detection with complex architecture[1-7].
基金supported by the National Key R&D Program of China(No.2023YFB2905600)the National Natural Science Foundation of China(Nos.61935005,62127802,62331004,62305067)the Key Project of Jiangsu Province of China(No.BE2023001-4)。
文摘We experimentally demonstrate the transmission of discrete multi-tone(DMT)millimeter-wave(mm-wave)signals over a 1.2-km distance at the D-band(110–170 GHz)in a cost-effective intensity-modulation and direct-detection(IM/DD)communication system.In the experiment,we successfully achieve the transmission of DMT-QPSK and DMT-16QAM mm-wave signals over multiple-input multiple-output(MIMO)links.After the 1.2-km free-space transmission,the bit error rate(BER)of the DMT-16QAM is below the 25%soft decision forward error correction(25%SD-FEC)threshold of 4×10^(-2),with a maximum net bit rate of 24.62 Gbit/s achieved in this system.
基金partially supported by the National Key R&D Projects of China(Grant No.2023YFB2905600)the National Natural Science Foundation of China(Grant Nos.61835002,61935005,62305067,62375219,62331004)the Jiangsu Province Key Project(Grant No.BE2023001-4)。
文摘In recent years,free space optical communication(FSO)has been a hot topic in satellite-to-ground communications,inter-satellite communications,and wireless access networks[1-4].It has the advantages of rich spectrum resources,no need for spectrum authorization,high spectrum efficiency verified by experiments,narrow beam angle,and low space loss under good weather.In point-to-point communications,the beam angle makes the FSO almost immune to multipath effects,and low-complexity Digital Signal Processing(DSP)algorithms can be used for recovery demodulation.
基金supported by the National Key R&D Program of China(Grant No.2023YFB2905600)the National Natural Science Foundation of China(Grant Nos.61835002,61935005,62305067,62375219,62331004)+2 种基金the Natural Science Foundation of Shaanxi Province(Grant No.2023-JC-JQ-58)Jiangsu Province Key Project(Grant No.BE2023001-4)the Innovation Capability Support Program of Shaanxi(Grant No.2021TD-09).
文摘Due to the rise of innovative technologies like artificial intelligence(AI),the Internet of Things(IoT),and telemedicine,the demand for internet traffic is rapidly increasing.In order to achieve ultra-high-speed wireless communication,many researchers are directing their efforts towards the Dband.The D-band,spanning the frequency band 110-170 GHz,has abundant spectrum resources and license-free characteristics[1,2].
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LDT23E0601)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(China)(No.2022C03146)+1 种基金the National Natural Science Foundation of China(Nos.U23A20677 and 22022610)the National Funded Postdoctoral Researcher Program of China(No.GZC20232363).
文摘Carbon capture,utilization and storage(CCUS)technologies play an essential role in achieving Net Zero Emissions targets.Considering the lack of timely reviews on the recent advancements in promising CCUS technologies,it is crucial to provide a prompt review of the CCUS advances to understand the current research gaps pertained to its industrial application.To that end,this review first summarized the developmental history of CCUS technologies and the current large-scale demonstrations.Then,based on a visually bibliometric analysis,the carbon capture remains a hotspot in the CCUS development.Noting that the materials applied in the carbon capture process determines its performance.As a result,the state-of-the-art carbon capture materials and emerging capture technologies were comprehensively summarized and discussed.Gaps between state-of-art carbon capture process and its ideal counterpart are analyzed,and insights into the research needs such as material design,process optimization,environmental impact,and technical and economic assessments are provided.
基金supported by the National Natural Science Foundation of China(Grant Nos.11772251,and 11802220)the 111 Project(Grant No.B18040)
文摘This study presents a two-dimensional phononic crystal with heat flux manipulation and wide bandgaps of out-of-plane modes within the low-frequency range. The anisotropic matrix made of spiral-multilayered materials with different thermal conductivities, and the coating layer inserted with metal are designed for heat flux manipulation. Rubber-coated metal cylinders are periodically embedded in the anisotropic matrix to obtain the low-frequency bandgaps of out-of-plane modes. Numerical simulation is carried out to validate the heat and elastic characteristics of the spiral-multilayered anisotropic structure and reveal the effects of the laying angle and temperature on the bandgaps. Subsequently, a spiral-multilayered plate with periodic structures is studied, which shows an obvious vibration attenuation in the frequency ranges of the bandgaps and a deflected heat flux from the initial propagation direction. In the experimental investigation, the multi-phase spiral-multilayered anisotropic plate is simplified to a single-phase anisotropic plate made of aluminum. The characteristics of this type of anisotropic phononic crystal structure may pave the way for the design of a new kind of thermo-acoustic metamaterial serving in combined thermal and acoustic environments.
基金supported by the National Key R&D Program of China(Grant No.2023YFB2905600)the National Natural Science Foundation of China(Grant Nos.62127802,62331004,62305067,U24B20142,U24B20168,62427815)the Key Project of Jiangsu Province of China(Grant No.BE2023001-4)。
文摘The International Telecommunication Union(ITU)has introduced the concept of“intelligent connectivity for 2030”,which is driving the development of 6G technology.This next-generation wireless network is finding applications across various sectors,including smart cities,autonomous driving,holographic imaging,and satellite communications.When compared to 5G,the demands for higher data transmission rates,lower latency,and more efficient use of spectrum have become even more critical.
基金supported by the National Key R&D Program of China(No.2023YFB2905600)the China Postdoctoral Science Foundation(No.2024M760537)+4 种基金the China Postdoctoral Program for Innovative Talents(No.BX20240077)the Open Fund of IPOC(BUPT)(No.IPOC2024A02)the Fund of State Key Laboratory of Photonics and Communications,China(No.2025QZKF06)the National Natural Science Foundation of China(Nos.62127802,62331004,62305067,U24B20142,U24B20168,and 62427815)the Natural Science Foundation of Shanghai(No.25ZR1402018)。
文摘In this paper,optoelectronic technology is used to effectively utilize bandwidth resources in the band of 110-170 GHz,thereby increasing system capacity.We use the flexible control characteristics of the operating frequency of optoelectronic technology,and large-scale frequency hopping communications are realized to avoid potential interference.We have achieved 24 Gbps full-band sub-THz transmission over 4.6 km within the continuous range of 110-170 GHz in the dense fog simulation environment based on advanced optoelectronic technology,and the carrier frequency is continuously adjustable with an accuracy value of less than 0.2%.In the continuous range of 125-155 GHz,demonstrations of full-band 40 Gbps over 4.6 km are reported.Our work is of reference significance for high-speed long-haul sub-THz band communications under stringent conditions.
