Optically levitated oscillators in high vacuum have excellent environmental isolation and low mass compared with conventional solid-state sensors,which makes them suitable for ultrasensitive force detection.The force ...Optically levitated oscillators in high vacuum have excellent environmental isolation and low mass compared with conventional solid-state sensors,which makes them suitable for ultrasensitive force detection.The force resolution usually scales with the measurement bandwidth,which represents the ultimate detection capability of the system under ideal conditions if sufficient time is provided for measurement.However,considering the stability of a real system,a method based on the Allan variance is more reliable to evaluate the actual force detection performance.In this study,a levitated optomechanical system with a force detection sensitivity of 6.33±1.62 zN/Hz^(1/2)was demonstrated.And for the first time,the Allan variance was introduced to evaluate the system stability due to the force sensitivity fluctuations.The force detection resolution of 166.40±55.48 yN was reached at the optimal measurement time of 2751 s.The system demonstrated in this work has the best force detection performance in both sensitivity and resolution that have been reported so far for optically levitated particles.The reported high-sensitivity force detection system is an excellent candidate for the exploration of new physics such as fifth force searching,high-frequency gravitational waves detection,dark matter research and so on.展开更多
The interrelationship between preload forces and natural frequencies of anchors was obtained from the structure of an anchor and its mechanical characteristics. We established a numerical model for the dynamic analysi...The interrelationship between preload forces and natural frequencies of anchors was obtained from the structure of an anchor and its mechanical characteristics. We established a numerical model for the dynamic analysis of a bolt support system taking into consideration the working surroundings of the anchor. The natural frequency distribution of the system under various preload forces of the anchor was analyzed with ANSYS. Our results show that each order of the system frequency varied with an increase in preload forces. A single order frequency decreased with an increase in the preload force. A preload force affected low-order frequencies more than high-order frequencies. We obtained a functional relationship by fitting preload forces and fundamental frequencies, which was in agreement with our theretical considerations. This study provides theoretical support for the detection of preload forces.展开更多
A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. Fi...A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. First, the analysis on extracting eddies＇ edges from remote sensing imagery using conventional edge detection arithmetic operators is performed and returns digitized vector edge data as a result. Second, attraction forces and fusion forces between edge curves were analyzed and calculated based on the vector eddy edges. Thirdly, the virtual significant spatial patterns of eddy were detected automatically using iterative repetition followed by optimized rule. Finally, the spatial form auto-detection of different types of ocean eddies was done using satellite images. The study verified that this is an effective way to identify and detect the ocean eddy with a complex form.展开更多
Levitated optomechanical systems represent an excellent candidate platform for force and acceleration sensing.We propose a force-sensing protocol utilizing an optically levitated nanoparticle array.In our scheme,N nan...Levitated optomechanical systems represent an excellent candidate platform for force and acceleration sensing.We propose a force-sensing protocol utilizing an optically levitated nanoparticle array.In our scheme,N nanoparticles are trapped in an optical cavity using holographic optical tweezers.An external laser drives the cavity,exciting N cavity modes interacting simultaneously with the N nanoparticles.The optomechanical interaction encodes the information of the force acting on each nanoparticle onto the intracavity photons,which can be detected directly at the output ports of the cavity.Consequently,our protocol enables real-time imaging of a force field.展开更多
A scheme for remote weak-signal sensors is proposed,in which a coupled-resonator optical waveguide(CROW),as a transmitter,couples to a hybrid optomechanical cavity and an observing cavity at its two ends.Non-Markovian...A scheme for remote weak-signal sensors is proposed,in which a coupled-resonator optical waveguide(CROW),as a transmitter,couples to a hybrid optomechanical cavity and an observing cavity at its two ends.Non-Markovian theory is employed to study the weak-force sensor by treating the CROW as a non-Markovian reservoir of cavity fields.The dissipationless bound states in the non-Markovian regime are conducive to remotely transmitting a signal in the CROW.Our results show that a sensor with ultrahigh sensitivity can be achieved with the assistance of bound states under certain parameter regimes.展开更多
The A-level tourist attractions are an important carrier for the development of the tourism industry.As the most fundamental tourism supply,studying their spatial distribution pattern and driving forces is of great si...The A-level tourist attractions are an important carrier for the development of the tourism industry.As the most fundamental tourism supply,studying their spatial distribution pattern and driving forces is of great significance for promoting the process of regional tourism industrialization.This study used the tourism resource abundance index,nearest neighbor distance index,and geographic detector model to study the spatial characteristics and driving forces of A-level tourist attractions in China.The results showed that the A-level tourist attractions in China exhibit significant spatial clustering,but there are significant regional differences.They are mainly distributed on the southeastern side of the Hu Huanyong Line.Overall,the average of tourism resource abundance index is 71.74.The proportion of cities above that average is relatively low,and they form local high-value clustering areas mainly in the Beijing-Tianjin-Hebei urban agglomeration,Yangtze River Delta,and Chengdu-Chongqing regions.The spatial distribution patterns of various types of scenic spots also exhibit agglomeration characteristics,but their agglomeration scales and spatial patterns exhibit obvious regional differences.The spatial distribution pattern of A-level tourist attractions in China is a result of the combined effect of regional socio-economic factors and scenic environmental factors.Among them,the explanatory power of regional socio-economic factors is stronger than that of scenic environmental factors.Among the scenic environmental factors,resource endowment has the strongest explanatory power,and there are significant differences in the dominant factors influencing the distributions of different types of A-level tourist attractions.展开更多
Sr0.6 Ba0.4 Nb2 O6 micro-rods are prepared by the molten-salt method with K2 SO4,KCl-K2 SO4,and KCl as fluxes.It reveals that the Sr0.6 Ba0.4 Nb2 O6 synthesized with KCl as a flux exhibits a single phase with tetragon...Sr0.6 Ba0.4 Nb2 O6 micro-rods are prepared by the molten-salt method with K2 SO4,KCl-K2 SO4,and KCl as fluxes.It reveals that the Sr0.6 Ba0.4 Nb2 O6 synthesized with KCl as a flux exhibits a single phase with tetragonal tungsten bronze structure.The measurement of X-ray diffraction indicates that the Sr0.6 Ba0.4 Nb2 O6 micro-rods synthesized at 1 300℃are anisotropic.The morphology of the powers is examined by transmission electron microscope.It reveals that the length-diameter ratio of Sr0.6 Ba0.4 Nb2 O6 micro-rods increases with increasing annealing temperature from 900℃to 1 300℃.At 1 300℃,the rod possesses a large length-diameter ratio of 8∶1.Moreover,the analysis of the piezoelectric properties of single micro-rods using apiezo-response force microscope indicates that the domains of the material are arranged along its radial direction.展开更多
A forced alignment based algorithms to detect Chinese repetitive stuttering is studied. According to the features of repetitions in Chinese stuttered speech,improvement solutions are provided based on the previous res...A forced alignment based algorithms to detect Chinese repetitive stuttering is studied. According to the features of repetitions in Chinese stuttered speech,improvement solutions are provided based on the previous research findings.First,a multi-span looping forced alignment decoding networks is designed to detect multi-syllable repetitions in Chinese stuttered speech.Second,branch penalty factor is added in the networks to adjust decoding trend using recursive search in order to reduce the error from the complexity of the decoding networks. Finally,we re-judge the detected stutters by calculating confidence to improve the reliability of the detection result.The experimental results show that compared to previous algorithm,the proposed algorithm can improve system performance significantly,about 18%average detection error rate relatively.展开更多
The non-destructive operation of intelligent underwater robotics with human-like sensory capabilities is essential for deep-sea resource exploration.However,extreme deep-sea hydrostatic pressure easily distorts sensor...The non-destructive operation of intelligent underwater robotics with human-like sensory capabilities is essential for deep-sea resource exploration.However,extreme deep-sea hydrostatic pressure easily distorts sensor signals or damages devices,and detecting hundred-pascal-level contact forces under tens-of-megapascal hydrostatic pressures presents a critical challenge that hinders the advancement of underwater tactile sensing technology.Inspired by deep-sea sponges’hydrostatic skeletal supporting mechanisms,we developed a fully open-pore hydrophobic ionogel as the sensing layer to construct a biomimetic deep-sea tactile sensor.The contact force is converted into electrical signals for object classification and non-destructive manipulation of marine organisms.This innovative sensing layer features aquatic stability and a pore structure balancing internal-external hydrostatic pressure,reducing environmental disturbances.The sensor maintains stable contact force detection under 50 MPa hydrostatic pressure,and accurately classify objects of varying hardness with an overall recognition accuracy of 95.5%,holding great potential for deep-sea exploration and sustainable resource exploitation.展开更多
Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by ...Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by the optical near field on the surface is measured as the electrostatic force. We demonstrated atomicresolution imaging of the near field on the α-Al2O3 （0001） surface of a prism. We investigated the spatial distribution of the near field by scanning at different tip-sample distances and found that the atomic corrugation of the near-field signal was observed at greater distances than that of the atomic force microscopy signal. As the tip-sample distance increased, the normalized signal-to-noise ratio of the near field is in a gradual decline almost twice that of the frequency shift （Δf）.展开更多
基金supported by grants from the National Natural Science Foundation of China(62005248,62075193)Major Project of Natural Science Foundation of Zhejiang Province(LD22F050002)+2 种基金Major Scientific Research Project of Zhejiang Lab(2019MB0AD01,2021MB0AL02,2022MB0AL02)the Fundamental Research Funds for the Central Universities,China(2016XZZX00401 and 2018FZA5002)the National Program for Special Support of Top-Notch Young Professionals(W02070390),China.
文摘Optically levitated oscillators in high vacuum have excellent environmental isolation and low mass compared with conventional solid-state sensors,which makes them suitable for ultrasensitive force detection.The force resolution usually scales with the measurement bandwidth,which represents the ultimate detection capability of the system under ideal conditions if sufficient time is provided for measurement.However,considering the stability of a real system,a method based on the Allan variance is more reliable to evaluate the actual force detection performance.In this study,a levitated optomechanical system with a force detection sensitivity of 6.33±1.62 zN/Hz^(1/2)was demonstrated.And for the first time,the Allan variance was introduced to evaluate the system stability due to the force sensitivity fluctuations.The force detection resolution of 166.40±55.48 yN was reached at the optimal measurement time of 2751 s.The system demonstrated in this work has the best force detection performance in both sensitivity and resolution that have been reported so far for optically levitated particles.The reported high-sensitivity force detection system is an excellent candidate for the exploration of new physics such as fifth force searching,high-frequency gravitational waves detection,dark matter research and so on.
基金the financial support from the National Basic Research Program of China (No. 2013CB227900)the China Postdoctoral Science Foundation (No. 20110491483)the State Key Laboratory of Coal Resources and Mine Safety(No. 10F08)
文摘The interrelationship between preload forces and natural frequencies of anchors was obtained from the structure of an anchor and its mechanical characteristics. We established a numerical model for the dynamic analysis of a bolt support system taking into consideration the working surroundings of the anchor. The natural frequency distribution of the system under various preload forces of the anchor was analyzed with ANSYS. Our results show that each order of the system frequency varied with an increase in preload forces. A single order frequency decreased with an increase in the preload force. A preload force affected low-order frequencies more than high-order frequencies. We obtained a functional relationship by fitting preload forces and fundamental frequencies, which was in agreement with our theretical considerations. This study provides theoretical support for the detection of preload forces.
文摘A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. First, the analysis on extracting eddies＇ edges from remote sensing imagery using conventional edge detection arithmetic operators is performed and returns digitized vector edge data as a result. Second, attraction forces and fusion forces between edge curves were analyzed and calculated based on the vector eddy edges. Thirdly, the virtual significant spatial patterns of eddy were detected automatically using iterative repetition followed by optimized rule. Finally, the spatial form auto-detection of different types of ocean eddies was done using satellite images. The study verified that this is an effective way to identify and detect the ocean eddy with a complex form.
基金the useful discussion.This work is supported by the Natural Science Foundation of Zhe-jiang Province(Grant No.LQ22A040010)the National Natural Science Foundation of China(Grant Nos.12304545 and 12204434).
文摘Levitated optomechanical systems represent an excellent candidate platform for force and acceleration sensing.We propose a force-sensing protocol utilizing an optically levitated nanoparticle array.In our scheme,N nanoparticles are trapped in an optical cavity using holographic optical tweezers.An external laser drives the cavity,exciting N cavity modes interacting simultaneously with the N nanoparticles.The optomechanical interaction encodes the information of the force acting on each nanoparticle onto the intracavity photons,which can be detected directly at the output ports of the cavity.Consequently,our protocol enables real-time imaging of a force field.
基金This work was supported by NSFC under Grant Nos.11874099 and 11674120.
文摘A scheme for remote weak-signal sensors is proposed,in which a coupled-resonator optical waveguide(CROW),as a transmitter,couples to a hybrid optomechanical cavity and an observing cavity at its two ends.Non-Markovian theory is employed to study the weak-force sensor by treating the CROW as a non-Markovian reservoir of cavity fields.The dissipationless bound states in the non-Markovian regime are conducive to remotely transmitting a signal in the CROW.Our results show that a sensor with ultrahigh sensitivity can be achieved with the assistance of bound states under certain parameter regimes.
基金The National Natural Science Foundation of China(42401207,42371195)The Youth Research Project of Humanities and Social Science of the Ministry of Education(22YJC790152)The Key Scientific Research Project of Colleges and Universities of Henan Province(23A790020)。
文摘The A-level tourist attractions are an important carrier for the development of the tourism industry.As the most fundamental tourism supply,studying their spatial distribution pattern and driving forces is of great significance for promoting the process of regional tourism industrialization.This study used the tourism resource abundance index,nearest neighbor distance index,and geographic detector model to study the spatial characteristics and driving forces of A-level tourist attractions in China.The results showed that the A-level tourist attractions in China exhibit significant spatial clustering,but there are significant regional differences.They are mainly distributed on the southeastern side of the Hu Huanyong Line.Overall,the average of tourism resource abundance index is 71.74.The proportion of cities above that average is relatively low,and they form local high-value clustering areas mainly in the Beijing-Tianjin-Hebei urban agglomeration,Yangtze River Delta,and Chengdu-Chongqing regions.The spatial distribution patterns of various types of scenic spots also exhibit agglomeration characteristics,but their agglomeration scales and spatial patterns exhibit obvious regional differences.The spatial distribution pattern of A-level tourist attractions in China is a result of the combined effect of regional socio-economic factors and scenic environmental factors.Among them,the explanatory power of regional socio-economic factors is stronger than that of scenic environmental factors.Among the scenic environmental factors,resource endowment has the strongest explanatory power,and there are significant differences in the dominant factors influencing the distributions of different types of A-level tourist attractions.
基金supported by the National Natural Science Foundation of China(No.11475086)
文摘Sr0.6 Ba0.4 Nb2 O6 micro-rods are prepared by the molten-salt method with K2 SO4,KCl-K2 SO4,and KCl as fluxes.It reveals that the Sr0.6 Ba0.4 Nb2 O6 synthesized with KCl as a flux exhibits a single phase with tetragonal tungsten bronze structure.The measurement of X-ray diffraction indicates that the Sr0.6 Ba0.4 Nb2 O6 micro-rods synthesized at 1 300℃are anisotropic.The morphology of the powers is examined by transmission electron microscope.It reveals that the length-diameter ratio of Sr0.6 Ba0.4 Nb2 O6 micro-rods increases with increasing annealing temperature from 900℃to 1 300℃.At 1 300℃,the rod possesses a large length-diameter ratio of 8∶1.Moreover,the analysis of the piezoelectric properties of single micro-rods using apiezo-response force microscope indicates that the domains of the material are arranged along its radial direction.
基金supported by the National Natural Science Foundation of China(10925419,90920302, 61072124,11074275,11161140319,91120001,61271426)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA06030100,XDA06030500)+1 种基金the National 863 Program(2012AA012503)the CAS Priority Deployment Project(KGZD-EW-103-2)
文摘A forced alignment based algorithms to detect Chinese repetitive stuttering is studied. According to the features of repetitions in Chinese stuttered speech,improvement solutions are provided based on the previous research findings.First,a multi-span looping forced alignment decoding networks is designed to detect multi-syllable repetitions in Chinese stuttered speech.Second,branch penalty factor is added in the networks to adjust decoding trend using recursive search in order to reduce the error from the complexity of the decoding networks. Finally,we re-judge the detected stutters by calculating confidence to improve the reliability of the detection result.The experimental results show that compared to previous algorithm,the proposed algorithm can improve system performance significantly,about 18%average detection error rate relatively.
基金support from the National Key R&D Program of China(No.2024YFB4707300)the National Natural Science Foundation of China(No.52550004,52188102,52475018)+3 种基金the Fundamental Research Funds for the Central Universities(HUST:YCJJ20242101)the STAR Project by the School of Mechanical Science and Engineering of Huazhong University of Science and Technologysupport from Flexible Electronics Research Center and Analytical and Testing Center of HUST for providing experiment facilitysupport from the National University of Singapore Presidential Young Professorship.
文摘The non-destructive operation of intelligent underwater robotics with human-like sensory capabilities is essential for deep-sea resource exploration.However,extreme deep-sea hydrostatic pressure easily distorts sensor signals or damages devices,and detecting hundred-pascal-level contact forces under tens-of-megapascal hydrostatic pressures presents a critical challenge that hinders the advancement of underwater tactile sensing technology.Inspired by deep-sea sponges’hydrostatic skeletal supporting mechanisms,we developed a fully open-pore hydrophobic ionogel as the sensing layer to construct a biomimetic deep-sea tactile sensor.The contact force is converted into electrical signals for object classification and non-destructive manipulation of marine organisms.This innovative sensing layer features aquatic stability and a pore structure balancing internal-external hydrostatic pressure,reducing environmental disturbances.The sensor maintains stable contact force detection under 50 MPa hydrostatic pressure,and accurately classify objects of varying hardness with an overall recognition accuracy of 95.5%,holding great potential for deep-sea exploration and sustainable resource exploitation.
文摘Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by the optical near field on the surface is measured as the electrostatic force. We demonstrated atomicresolution imaging of the near field on the α-Al2O3 （0001） surface of a prism. We investigated the spatial distribution of the near field by scanning at different tip-sample distances and found that the atomic corrugation of the near-field signal was observed at greater distances than that of the atomic force microscopy signal. As the tip-sample distance increased, the normalized signal-to-noise ratio of the near field is in a gradual decline almost twice that of the frequency shift （Δf）.
