Aiming at the problem of large fading noise in Rayleigh Brillouin optical time domain analysis system, a wavelength scanning technique is proposed to enhance the performance of the temperature sensing system. The prin...Aiming at the problem of large fading noise in Rayleigh Brillouin optical time domain analysis system, a wavelength scanning technique is proposed to enhance the performance of the temperature sensing system. The principle of the proposed technique to reduce the fading noise is introduced based on the analysis of Rayleigh Brillouin optical time domain analysis system. The experimental results show that the signal-to-noise ratio(SNR) at the end of optical fiber with length of 50 m after 17 times wavelength scanning is 5.21 d B higher than that with single wavelength, the Brillouin frequency shift(BFS) on the heated fiber with length of 70 m inserted at the center of sensing fiber can be accurately measured as 0.19 MHz, which is equivalent to a measurement accuracy of 0.19 °C. It indicates that the proposed technique can realize high-accuracy temperature measurement and has huge potential in the field of long-distance and high-accuracy sensing.展开更多
We consider the spectrum handoff delay of a Secondary User(SU)in cognitive radio networks.We propose a spectrum handoff scheme based on Recommended Channel Sensing Sequence(RCSS),which aims to optimise the spectrum ha...We consider the spectrum handoff delay of a Secondary User(SU)in cognitive radio networks.We propose a spectrum handoff scheme based on Recommended Channel Sensing Sequence(RCSS),which aims to optimise the spectrum handoff delay subject to the sensing reliability and link maintenance constraints.There are two cases that should be considered:1)the SU performs spectrum handoff successfully during the current frame,and 2)the SU successfully performs the spectrum handoff using several frames.We develop a dynamic programming algorithm for RCSS to identify the optimal sensing sequence for the first case,and an updating algorithm for RCSS to improve the handoff performance for the second case.The numerical results confirm that the proposed RCSS handoff scheme can achieve better handoff delay performance than others when the received signal-to-noise ratios of the Pus' signals on different channels are non-identical.展开更多
The popularity of mobile devices with sensors is captivating the attention of researchers to modern techniques,such as the internet of things(IoT)and mobile crowdsensing(MCS).The core concept behind MCS is to use the ...The popularity of mobile devices with sensors is captivating the attention of researchers to modern techniques,such as the internet of things(IoT)and mobile crowdsensing(MCS).The core concept behind MCS is to use the power of mobile sensors to accomplish a difficult task collaboratively,with each mobile user completing much simpler micro-tasks.This paper discusses the task assignment problem in mobile crowdsensing,which is dependent on sensing time and path planning with the constraints of participant travel distance budgets and sensing time intervals.The goal is to minimize aggregate sensing time for mobile users,which reduces energy consumption to encourage more participants to engage in sensing activities and maximize total task quality.This paper introduces a two-phase task assignment framework called location time-based algorithm(LTBA).LTBA is a framework that enhances task assignment in MCS,whereas assigning tasks requires overlapping time intervals between tasks and mobile users’tasks and the location of tasks and mobile users’paths.The process of assigning the nearest task to the mobile user’s current path depends on the ant colony optimization algorithm(ACO)and Euclidean distance.LTBA combines two algorithms:(1)greedy online allocation algorithm and(2)bio-inspired traveldistance-balance-based algorithm(B-DBA).The greedy algorithm was sensing time interval-based and worked on reducing the overall sensing time of the mobile user.B-DBA was location-based and worked on maximizing total task quality.The results demonstrate that the average task quality is 0.8158,0.7093,and 0.7733 for LTBA,B-DBA,and greedy,respectively.The sensing time was reduced to 644,1782,and 685 time units for LTBA,B-DBA,and greedy,respectively.Combining the algorithms improves task assignment in MCS for both total task quality and sensing time.The results demonstrate that combining the two algorithms in LTBA is the best performance for total task quality and total sensing time,and the greedy algorithm follows it then B-DBA.展开更多
Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern...Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern China was used as a case study.A Landsat time series stack(LTSS) was fed to the vegetation change tracker model(VCT) to map long-term changes in plantation forests' disturbance and recovery,followed by an intensive validation and a continuous 27-yr change analysis on disturbance locations,magnitudes and rates of plantations' disturbance and recovery.And the validation results of the disturbance year maps derived from five randomly identified sample plots with 25 km^2 located at the four corners and the center of the scene showed the majority of the spatial agreement measures ranged from 60% to 83%.A confusion matrix summary of the accuracy measures for all four validation sites in Fogang County showed that the disturbance year maps had an overall accuracy estimate of 71.70%.Forest disturbance rates' change trend was characterized by a decline first,followed by an increase,then giving way to a decline again.An undulated and gentle decreasing trend of disturbance rates from the highest value of 3.95% to the lowest value of 0.76% occurred between 1988 and 2001,disturbance rate of 4.51% in 1994 was a notable anomaly,while after 2001 there was a sharp ascending change,forest disturbance rate spiked in 2007(5.84%).After that,there was a significant decreasing trend up to the lowest value of 1.96% in 2011 and a slight ascending trend from 2011 to 2015(2.59%).Two obvious spikes in post-disturbance recovery rates occurred in 1995(0.26%) and 2008(0.41%).Overall,forest recovery rates were lower than forest disturbance rates.Moreover,forest disturbance and recovery detection based on VCT and the Landsat-based detections of trends in disturbance and recovery(LandT rendr) algorithms in Fogang County have been conducted,with LandT rendr finding mostly much more disturbance than VCT.Overall,disturbances and recoveries in northern Guangdong were triggered mostly by timber needs,policies and decisions of the local governments.This study highlights that a better understanding about plantations' changes would provide a critical foundation for local forest management decisions in the southern China.展开更多
In the process of image transmission, the famous JPEG and JPEG-2000 compression methods need more transmission time as it is difficult for them to compress the image with a low compression rate. Recently the compresse...In the process of image transmission, the famous JPEG and JPEG-2000 compression methods need more transmission time as it is difficult for them to compress the image with a low compression rate. Recently the compressed sensing（CS） theory was proposed, which has earned great concern as it can compress an image with a low compression rate, meanwhile the original image can be perfectly reconstructed from only a few compressed data. The CS theory is used to transmit the high resolution astronomical image and build the simulation environment where there is communication between the satellite and the Earth. Number experimental results show that the CS theory can effectively reduce the image transmission and reconstruction time. Even with a very low compression rate, it still can recover a higher quality astronomical image than JPEG and JPEG-2000 compression methods.展开更多
Due to the fact that the conventional spectrum sensing algorithm is susceptible to noise, an adaptive double-threshold energy detection algorithm for a cognitive radio is proposed. Based on double-threshold energy det...Due to the fact that the conventional spectrum sensing algorithm is susceptible to noise, an adaptive double-threshold energy detection algorithm for a cognitive radio is proposed. Based on double-threshold energy detection, the algorithm can adaptively switch between one-round sensing and two-round sensing by comparing the observations with the pre-fixed thresholds. Mathematical expressions for the probability of detection, the probability of false alarm, and the sensing time are derived. The relationships including signal to noise ratio （SNR） vs. the probability of detection and SNR vs. the sensing time are plotted using Monte Carlo simulation and the algorithm is verified in a real cognitive system based on GNU Radio and universal software radio peripheral （USRP）. Simulation and experimental results show that, compared with the existing spectrum sensing method, the proposed algorithm can achieve a higher probability of detection within a reasonable sensing time.展开更多
Based on TIMESAT 3.2 platform, MODIS NDVI data(2000–2015) of Qaidam Basin are fitted, and three main phenological parameters are extracted with the method of dynamic threshold, including the start of growth season(SG...Based on TIMESAT 3.2 platform, MODIS NDVI data(2000–2015) of Qaidam Basin are fitted, and three main phenological parameters are extracted with the method of dynamic threshold, including the start of growth season(SGS), the end of growth season(EGS) and the length of growth season(LGS). The spatial and temporal variation of vegetation phenology and its response to climate changes are analyzed respectively. The conclusions are as follows:(1) SGS is mainly delayed as a whole. Areas delayed are more than the advanced in EGS, and EGS is a little delayed as a whole. LGS is generally shortened.(2) With the altitude rising, SGS is delayed, EGS is advanced, and LGS is shortened and phenophase appears a big variation below 3000 m and above 5000 m.(3) From 2000 to 2015, the temperature appears a slight increase along with a big fluctuation, and the precipitation increases evidently.(4) Response of phenophase to precipitation is not obvious in the low elevation humid regions, where SGS arrives early and EGS delays; while, in the upper part of the mountain regions, SGS delays and EGS advances with temperature rising, SGS arrives early and EGS delays with precipitation increasing.展开更多
Real-time wide-area environment sensing is crucial for accessing open-world information streams from nature and human society.As a transformative technique distinct from electrical sensors,distributed optical fiber se...Real-time wide-area environment sensing is crucial for accessing open-world information streams from nature and human society.As a transformative technique distinct from electrical sensors,distributed optical fiber sensing especially for Brillouin scattering-based paradigm has shown superior bandwidth,power,and sensing range.Still,it suffers from insufficient resolution and timeliness to characterize remote dynamic events.Here we develop TABS—a transient acoustic wave-based Brillouin optical time domain analysis sensor,supporting long-range highspatiotemporal-resolution distributed sensing.By designing a functionally synergistic sensor architecture,TABS elaborately leverages wideband and time-weighted energy transformation properties of a transient acousto-optic interaction to breaking through Brillouin-energy-utilization-efficiency bottleneck,enabling enhancements in overall sensing performance.In the experiment,TABS has achieved a 37-cm spatial resolution over a 50-km range with 1 to 2 orders of magnitude improvement in temporal resolution compared to prevailing Brillouin sensing approaches.For the first time,TABS is explored for state imaging of evacuated-tube maglev transportation system as an exemplary application,showcasing its feasibility and flexibility for potential open-world applications and large-scale intelligent perception.展开更多
Improvements to body-surface physiological monitoring ability including real-time,accuracy and integration,are essential to meet the expansive demands for personal healthcare.As part of this,simultaneous monitoring of...Improvements to body-surface physiological monitoring ability including real-time,accuracy and integration,are essential to meet the expansive demands for personal healthcare.As part of this,simultaneous monitoring of sweat metabolites and body temperature offers an exciting path to maximizing diagnostic precision and minimizing morbidity rates.Herein,we report a high-performance biomarker-temperature sensor made of a single As_(3)Se_(5)Te_(2)chalcogenide glass fiber to monitor physiology evolution on body-surface.The sensor integrates efficient thermal resistance and fiber evanescent wave effects,permitting the independent sensing of temperature and biomarkers with an ultrahigh temperature coefficient of resistance(−5.84%K^(–1)),rapid temperature response(0.3 s)and excellent IR sensing sensitivity.Moreover,by attaching a fiber to the wrist,we demonstrate simultaneous observation of both sweat metabolite(urea and lactate)and temperature changes during exercise.This illuminating sensing method will provide crucial capabilities in physiological monitoring and pave the way for advanced personalized diagnostic.展开更多
Real-time thermal sensing through flexible temperature sensors in extreme environments is critically essential for precisely monitoring chemical reactions,propellant combustions,and metallurgy processes.However,despit...Real-time thermal sensing through flexible temperature sensors in extreme environments is critically essential for precisely monitoring chemical reactions,propellant combustions,and metallurgy processes.However,despite their low response speed,most existing thermal sensors and related sensing materials will degrade or even lose their sensing performances at either high or low temperatures.Achieving a microsecond response time over an ultrawide temperature range remains challenging.Here,we design a flexible temperature sensor that employs ultrathin and consecutive Mo_(1−x)W_(x)S_(2) alloy films constructed via inkjet printing and a thermal annealing strategy.The sensing elements exhibit a broad work range(20 to 823 K on polyimide and 1,073 K on flexible mica)and a record-low response time(about 30μs).These properties enable the sensors to detect instantaneous temperature variations induced by contact with liquid nitrogen,water droplets,and flames.Furthermore,a thermal sensing array offers the spatial mapping of arbitrary shapes,heat conduction,and cold traces even under bending deformation.This approach paves the way for designing unique sensitive materials and flexible sensors for transient sensing under harsh conditions.展开更多
This paper focuses on the energy efficiency of cognitive relay （CR） networks with cooperative sensing, joint optimization of the sensing time and the signal-to-noise ratio （SNR） is studied to maximize the energy e...This paper focuses on the energy efficiency of cognitive relay （CR） networks with cooperative sensing, joint optimization of the sensing time and the signal-to-noise ratio （SNR） is studied to maximize the energy efficiency of CR network. Theoretical analysis shows that there exists an optimal sensing time and optimal SNR to make the energy efficiency maximized under a constraint of detection probability. Simulation results illustrate that the optimal fusion rule performs better than the OR rule and the AND rule in terms of the energy efficiency. By properly designing the fusion rule threshold as well as the number of cooperative sensing users, the energy efficiency of CR networks can be further improved.展开更多
The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporat...The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporated into the sensing of biomarkers,limiting the richness of sensing results.In this study,we report a time sequential sensing scheme for uric acid in sweat through a sequential design of Tesla valve channels.Graphene electrodes for detecting uric acid and directional Tesla valve flow channels were fabricated using laser engraving technology to realize time sequential sensing.The performance of the channels was verified through simulation.The time sequential detection of uric acid concentration in sweat can help researchers improve the establishment of human health management systems through flexible wearable devices.展开更多
Microwave imagers have attracted great interest because of their non-contact and high-penetration advantages,but conventional microwave imagers require complex hardware structures and time-consuming data acquisition,l...Microwave imagers have attracted great interest because of their non-contact and high-penetration advantages,but conventional microwave imagers require complex hardware structures and time-consuming data acquisition,limiting their further applications in real-time sensing.To solve the limitations,we propose a Ku-band microwave staring imager for front-view imaging with a single receiver based on a 1-bit transmissive programmable metasur-face.By dynamically changing the coding patterns on the metasurface according to the Hadamard matrix,the imager can reconstruct the given images according to the data collected by the receiver.With a simple hardware architecture and a compact structure,the proposed imager fulfills high-quality image reconstructions with high recognition accuracy in the task of microwave sensing,implying its broad application prospects,such as in security inspection,sensing,and medical examination.展开更多
基金supported by the National Natural Science Foundation of China(No.61377088)the Natural Science Foundation of Hebei Province of China(Nos.E2015502053 and F2015502059)the Fundamental Research Funds for the Central Universities(No.2016XS104)
文摘Aiming at the problem of large fading noise in Rayleigh Brillouin optical time domain analysis system, a wavelength scanning technique is proposed to enhance the performance of the temperature sensing system. The principle of the proposed technique to reduce the fading noise is introduced based on the analysis of Rayleigh Brillouin optical time domain analysis system. The experimental results show that the signal-to-noise ratio(SNR) at the end of optical fiber with length of 50 m after 17 times wavelength scanning is 5.21 d B higher than that with single wavelength, the Brillouin frequency shift(BFS) on the heated fiber with length of 70 m inserted at the center of sensing fiber can be accurately measured as 0.19 MHz, which is equivalent to a measurement accuracy of 0.19 °C. It indicates that the proposed technique can realize high-accuracy temperature measurement and has huge potential in the field of long-distance and high-accuracy sensing.
基金supported by the National Natural Science Foundation of China under Grant No. 61172067
文摘We consider the spectrum handoff delay of a Secondary User(SU)in cognitive radio networks.We propose a spectrum handoff scheme based on Recommended Channel Sensing Sequence(RCSS),which aims to optimise the spectrum handoff delay subject to the sensing reliability and link maintenance constraints.There are two cases that should be considered:1)the SU performs spectrum handoff successfully during the current frame,and 2)the SU successfully performs the spectrum handoff using several frames.We develop a dynamic programming algorithm for RCSS to identify the optimal sensing sequence for the first case,and an updating algorithm for RCSS to improve the handoff performance for the second case.The numerical results confirm that the proposed RCSS handoff scheme can achieve better handoff delay performance than others when the received signal-to-noise ratios of the Pus' signals on different channels are non-identical.
文摘The popularity of mobile devices with sensors is captivating the attention of researchers to modern techniques,such as the internet of things(IoT)and mobile crowdsensing(MCS).The core concept behind MCS is to use the power of mobile sensors to accomplish a difficult task collaboratively,with each mobile user completing much simpler micro-tasks.This paper discusses the task assignment problem in mobile crowdsensing,which is dependent on sensing time and path planning with the constraints of participant travel distance budgets and sensing time intervals.The goal is to minimize aggregate sensing time for mobile users,which reduces energy consumption to encourage more participants to engage in sensing activities and maximize total task quality.This paper introduces a two-phase task assignment framework called location time-based algorithm(LTBA).LTBA is a framework that enhances task assignment in MCS,whereas assigning tasks requires overlapping time intervals between tasks and mobile users’tasks and the location of tasks and mobile users’paths.The process of assigning the nearest task to the mobile user’s current path depends on the ant colony optimization algorithm(ACO)and Euclidean distance.LTBA combines two algorithms:(1)greedy online allocation algorithm and(2)bio-inspired traveldistance-balance-based algorithm(B-DBA).The greedy algorithm was sensing time interval-based and worked on reducing the overall sensing time of the mobile user.B-DBA was location-based and worked on maximizing total task quality.The results demonstrate that the average task quality is 0.8158,0.7093,and 0.7733 for LTBA,B-DBA,and greedy,respectively.The sensing time was reduced to 644,1782,and 685 time units for LTBA,B-DBA,and greedy,respectively.Combining the algorithms improves task assignment in MCS for both total task quality and sensing time.The results demonstrate that combining the two algorithms in LTBA is the best performance for total task quality and total sensing time,and the greedy algorithm follows it then B-DBA.
基金Under the auspices of the‘948’Project sponsored by the State Forestry Administration(SFA)of China(No.2014-4-25)National Natural Science Foundation of China(No.31670552,31270587)Doctorate Fellowship Foundation of Nanjing Forestry University,the PAPD(Priority Academic Program Development)of Jiangsu Provincial Universities,Graduate Research and Innovation Projects in Jiangsu Province(No.KYLX15_0908)
文摘Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern China was used as a case study.A Landsat time series stack(LTSS) was fed to the vegetation change tracker model(VCT) to map long-term changes in plantation forests' disturbance and recovery,followed by an intensive validation and a continuous 27-yr change analysis on disturbance locations,magnitudes and rates of plantations' disturbance and recovery.And the validation results of the disturbance year maps derived from five randomly identified sample plots with 25 km^2 located at the four corners and the center of the scene showed the majority of the spatial agreement measures ranged from 60% to 83%.A confusion matrix summary of the accuracy measures for all four validation sites in Fogang County showed that the disturbance year maps had an overall accuracy estimate of 71.70%.Forest disturbance rates' change trend was characterized by a decline first,followed by an increase,then giving way to a decline again.An undulated and gentle decreasing trend of disturbance rates from the highest value of 3.95% to the lowest value of 0.76% occurred between 1988 and 2001,disturbance rate of 4.51% in 1994 was a notable anomaly,while after 2001 there was a sharp ascending change,forest disturbance rate spiked in 2007(5.84%).After that,there was a significant decreasing trend up to the lowest value of 1.96% in 2011 and a slight ascending trend from 2011 to 2015(2.59%).Two obvious spikes in post-disturbance recovery rates occurred in 1995(0.26%) and 2008(0.41%).Overall,forest recovery rates were lower than forest disturbance rates.Moreover,forest disturbance and recovery detection based on VCT and the Landsat-based detections of trends in disturbance and recovery(LandT rendr) algorithms in Fogang County have been conducted,with LandT rendr finding mostly much more disturbance than VCT.Overall,disturbances and recoveries in northern Guangdong were triggered mostly by timber needs,policies and decisions of the local governments.This study highlights that a better understanding about plantations' changes would provide a critical foundation for local forest management decisions in the southern China.
文摘In the process of image transmission, the famous JPEG and JPEG-2000 compression methods need more transmission time as it is difficult for them to compress the image with a low compression rate. Recently the compressed sensing（CS） theory was proposed, which has earned great concern as it can compress an image with a low compression rate, meanwhile the original image can be perfectly reconstructed from only a few compressed data. The CS theory is used to transmit the high resolution astronomical image and build the simulation environment where there is communication between the satellite and the Earth. Number experimental results show that the CS theory can effectively reduce the image transmission and reconstruction time. Even with a very low compression rate, it still can recover a higher quality astronomical image than JPEG and JPEG-2000 compression methods.
基金The National Science and Technology Major Project (No. 2010ZX03006-002-01)the National Natural Science Foundation of China(No. 60972026 )the Cultivation Fund of the Key Scientific and Technical Innovation Project, Ministry of Education of China (No. 708046)
文摘Due to the fact that the conventional spectrum sensing algorithm is susceptible to noise, an adaptive double-threshold energy detection algorithm for a cognitive radio is proposed. Based on double-threshold energy detection, the algorithm can adaptively switch between one-round sensing and two-round sensing by comparing the observations with the pre-fixed thresholds. Mathematical expressions for the probability of detection, the probability of false alarm, and the sensing time are derived. The relationships including signal to noise ratio （SNR） vs. the probability of detection and SNR vs. the sensing time are plotted using Monte Carlo simulation and the algorithm is verified in a real cognitive system based on GNU Radio and universal software radio peripheral （USRP）. Simulation and experimental results show that, compared with the existing spectrum sensing method, the proposed algorithm can achieve a higher probability of detection within a reasonable sensing time.
基金National Natural Science Foundation of China,No.40971118Physical Geography Key Disciplines Construction Subjects of Hebei Province
文摘Based on TIMESAT 3.2 platform, MODIS NDVI data(2000–2015) of Qaidam Basin are fitted, and three main phenological parameters are extracted with the method of dynamic threshold, including the start of growth season(SGS), the end of growth season(EGS) and the length of growth season(LGS). The spatial and temporal variation of vegetation phenology and its response to climate changes are analyzed respectively. The conclusions are as follows:(1) SGS is mainly delayed as a whole. Areas delayed are more than the advanced in EGS, and EGS is a little delayed as a whole. LGS is generally shortened.(2) With the altitude rising, SGS is delayed, EGS is advanced, and LGS is shortened and phenophase appears a big variation below 3000 m and above 5000 m.(3) From 2000 to 2015, the temperature appears a slight increase along with a big fluctuation, and the precipitation increases evidently.(4) Response of phenophase to precipitation is not obvious in the low elevation humid regions, where SGS arrives early and EGS delays; while, in the upper part of the mountain regions, SGS delays and EGS advances with temperature rising, SGS arrives early and EGS delays with precipitation increasing.
基金supported in part by National Natural Science Foundation of China(NSFC)under contracts Nos.U23A20376,62431024,61735015,62405153,62205176.
文摘Real-time wide-area environment sensing is crucial for accessing open-world information streams from nature and human society.As a transformative technique distinct from electrical sensors,distributed optical fiber sensing especially for Brillouin scattering-based paradigm has shown superior bandwidth,power,and sensing range.Still,it suffers from insufficient resolution and timeliness to characterize remote dynamic events.Here we develop TABS—a transient acoustic wave-based Brillouin optical time domain analysis sensor,supporting long-range highspatiotemporal-resolution distributed sensing.By designing a functionally synergistic sensor architecture,TABS elaborately leverages wideband and time-weighted energy transformation properties of a transient acousto-optic interaction to breaking through Brillouin-energy-utilization-efficiency bottleneck,enabling enhancements in overall sensing performance.In the experiment,TABS has achieved a 37-cm spatial resolution over a 50-km range with 1 to 2 orders of magnitude improvement in temporal resolution compared to prevailing Brillouin sensing approaches.For the first time,TABS is explored for state imaging of evacuated-tube maglev transportation system as an exemplary application,showcasing its feasibility and flexibility for potential open-world applications and large-scale intelligent perception.
基金supported by the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(Grant No.2025C01166)National Natural Science Foundation of China(Grant Nos.62105168,62122039)+2 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LY23F050006)Ningbo Natural Science Foundation(Grant No.2024J460)sponsored by K.C.Wong Magna Fund in Ningbo University.
文摘Improvements to body-surface physiological monitoring ability including real-time,accuracy and integration,are essential to meet the expansive demands for personal healthcare.As part of this,simultaneous monitoring of sweat metabolites and body temperature offers an exciting path to maximizing diagnostic precision and minimizing morbidity rates.Herein,we report a high-performance biomarker-temperature sensor made of a single As_(3)Se_(5)Te_(2)chalcogenide glass fiber to monitor physiology evolution on body-surface.The sensor integrates efficient thermal resistance and fiber evanescent wave effects,permitting the independent sensing of temperature and biomarkers with an ultrahigh temperature coefficient of resistance(−5.84%K^(–1)),rapid temperature response(0.3 s)and excellent IR sensing sensitivity.Moreover,by attaching a fiber to the wrist,we demonstrate simultaneous observation of both sweat metabolite(urea and lactate)and temperature changes during exercise.This illuminating sensing method will provide crucial capabilities in physiological monitoring and pave the way for advanced personalized diagnostic.
基金supported by the National Natural Science Foundation of China(62304182,62371397,and 62288102)the Natural Science Foundation of Shaanxi Province(2023-JC-YB-495)+1 种基金the Fundamental Research Funds for the Central Universitiesthe start-up funds from Northwestern Polytechnical University(G2022WD01001 and 23GH02021).
文摘Real-time thermal sensing through flexible temperature sensors in extreme environments is critically essential for precisely monitoring chemical reactions,propellant combustions,and metallurgy processes.However,despite their low response speed,most existing thermal sensors and related sensing materials will degrade or even lose their sensing performances at either high or low temperatures.Achieving a microsecond response time over an ultrawide temperature range remains challenging.Here,we design a flexible temperature sensor that employs ultrathin and consecutive Mo_(1−x)W_(x)S_(2) alloy films constructed via inkjet printing and a thermal annealing strategy.The sensing elements exhibit a broad work range(20 to 823 K on polyimide and 1,073 K on flexible mica)and a record-low response time(about 30μs).These properties enable the sensors to detect instantaneous temperature variations induced by contact with liquid nitrogen,water droplets,and flames.Furthermore,a thermal sensing array offers the spatial mapping of arbitrary shapes,heat conduction,and cold traces even under bending deformation.This approach paves the way for designing unique sensitive materials and flexible sensors for transient sensing under harsh conditions.
基金supported by the National Science Fund under Grant No. 6087215the Yunnan Research Program of Application Foundation under Grant No.2011FB035the School training fund under granted No.KKZ3201403010
文摘This paper focuses on the energy efficiency of cognitive relay （CR） networks with cooperative sensing, joint optimization of the sensing time and the signal-to-noise ratio （SNR） is studied to maximize the energy efficiency of CR network. Theoretical analysis shows that there exists an optimal sensing time and optimal SNR to make the energy efficiency maximized under a constraint of detection probability. Simulation results illustrate that the optimal fusion rule performs better than the OR rule and the AND rule in terms of the energy efficiency. By properly designing the fusion rule threshold as well as the number of cooperative sensing users, the energy efficiency of CR networks can be further improved.
基金supported by the National Key R&D Program of China(No.2018YFA0108100)the National Natural Science Foundation of China(No.62104009)Experiments on human sweat were conducted in accordance with the approved protocol from the institutional review board at Peking University Third Hospital,Beijing,China(No.M2021610).
文摘The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporated into the sensing of biomarkers,limiting the richness of sensing results.In this study,we report a time sequential sensing scheme for uric acid in sweat through a sequential design of Tesla valve channels.Graphene electrodes for detecting uric acid and directional Tesla valve flow channels were fabricated using laser engraving technology to realize time sequential sensing.The performance of the channels was verified through simulation.The time sequential detection of uric acid concentration in sweat can help researchers improve the establishment of human health management systems through flexible wearable devices.
基金National Natural Science Foundation of China(62288101)China National Postdoctoral Program for Innovative Talents(BX20200080)+3 种基金China National Postdoctoral Science Foundation(2021M690603)National Key Research and Development Program of China(2023YFB3811300,2023YFB3811302)Natural Science Foundationof Jiangsu province−(BK20210210,BK20212002)FundamentalResearch Funds for the Central Universities(2242023K5002).
文摘Microwave imagers have attracted great interest because of their non-contact and high-penetration advantages,but conventional microwave imagers require complex hardware structures and time-consuming data acquisition,limiting their further applications in real-time sensing.To solve the limitations,we propose a Ku-band microwave staring imager for front-view imaging with a single receiver based on a 1-bit transmissive programmable metasur-face.By dynamically changing the coding patterns on the metasurface according to the Hadamard matrix,the imager can reconstruct the given images according to the data collected by the receiver.With a simple hardware architecture and a compact structure,the proposed imager fulfills high-quality image reconstructions with high recognition accuracy in the task of microwave sensing,implying its broad application prospects,such as in security inspection,sensing,and medical examination.
