This study analyzes live facial videos for recognizing nonverbal learning-related facial movements and head poses to discover the learning status of students. First, color and depth facial videos captured by a Kinect ...This study analyzes live facial videos for recognizing nonverbal learning-related facial movements and head poses to discover the learning status of students. First, color and depth facial videos captured by a Kinect are analyzed for face tracking using a three-dimensional （3D） active appearance model （AAM）. Second, the facial feature vector sequences are used to train hidden Markov models （HMMs） to recognize seven learning-related facial movements （smile, blink, frown, shake, nod, yawn, and talk）. The final stage involves the analysis of the facial movement vector sequence to evaluate three status scores （understanding, interaction, and consciousness）, each represents the learning status of a student and is helpful to both teachers and students for improving teaching and learning. Five teaching activities demonstrate that the proposed learning status analysis system promotes the interpersonal communication between teachers and students.展开更多
Abundant system operation state information is included in the electrical signal of the hydraulic system motor.How to accurately extract and classify the operation information of electrical signal is the key to realiz...Abundant system operation state information is included in the electrical signal of the hydraulic system motor.How to accurately extract and classify the operation information of electrical signal is the key to realize the condition monitoring of hydraulic system.The early fault characteristics of hydraulic gear pump hidden in the motor current signal are weak and difficult to extract by traditional time-frequency analysis.Based on the correlation coefficient and artificial bee colony algorithm(ABC),the parameter optimization of variational mode decomposition(VMD)is realized in this paper.At the same time,the principle of maximum signal correlation coefficient and kurtosis value is adopted to determine the effective intrinsic mode function(IMF).Moreover,the permutation entropy(PE)and root mean square(RMS)of the effective IMF components are input into the deep belief network(DBN-DNN)as high-dimensional feature vectors.The operation state of gear pump is monitored.The results show that the weak characteristics of current signal of gear pump fault are accurately and stably extracted by this method.The running state of gear pump is monitored and the accuracy of gear fault diagnosis is improved.展开更多
Purpose–This study aimed to facilitate a rapid evaluation of track service status and vehicle ride comfort based on car body acceleration.Consequently,a low-cost,data-driven approach was proposed for analyzing speed-...Purpose–This study aimed to facilitate a rapid evaluation of track service status and vehicle ride comfort based on car body acceleration.Consequently,a low-cost,data-driven approach was proposed for analyzing speed-related acceleration limits in metro systems.Design/methodology/approach–A portable sensing terminal was developed to realize easy and efficient detection of car body acceleration.Further,field measurements were performed on a 51.95-km metro line.Data from 272 metro sections were tested as a case study,and a quantile regression method was proposed to fit the control limits of the car body acceleration at different speeds using the measured data.Findings–First,the frequency statistics of the measured data in the speed-acceleration dimension indicated that the car body acceleration was primarily concentrated within the constant speed stage,particularly at speeds of 15.4,18.3,and 20.9 m/s.Second,resampling was performed according to the probability density distribution of car body acceleration for different speed domains to achieve data balance.Finally,combined with the traditional linear relationship between speed and acceleration,the statistical relationships between the speed and car body acceleration under different quantiles were determined.We concluded the lateral/vertical quantiles of 0.8989/0.9895,0.9942/0.997,and 0.9998/0.993 as being excellent,good,and qualified control limits,respectively,for the lateral and vertical acceleration of the car body.In addition,regression lines for the speedrelated acceleration limits at other quantiles(0.5,0.75,2s,and 3s)were obtained.Originality/value–The proposed method is expected to serve as a reference for further studies on speedrelated acceleration limits in rail transit systems.展开更多
The tradeoffs between the spatial and temporal resolutions for the remote sensing instruments limit their capacity to monitor the eutrophic status of inland lakes.Spatiotemporal fusion(STF)provides a cost-effective wa...The tradeoffs between the spatial and temporal resolutions for the remote sensing instruments limit their capacity to monitor the eutrophic status of inland lakes.Spatiotemporal fusion(STF)provides a cost-effective way to obtain remote sensing data with both high spatial and temporal resolutions by blending multisensor observations.However,remote sensing reflectance(Rrs)over water surface with a relatively low signal-to-noise ratio is prone to be contaminated by large uncertainties in the fusion process.To present a comprehensive analysis on the influence of processing and modeling errors,we conducted an evaluation study to understand the potential,uncertainties,and limitations of using STF for monitoring chlorophyll a(Chla)concentration in an inland eutrophic water(Chaohu Lake,China).Specifically,comparative tests were conducted on the Sentinel-2 and Sentinel-3 image pairs.Three typical STF methods were selected for comparison,i.e.,Fit-FC,spatial and temporal nonlocal filter-based fusion model,and the flexible spatiotemporal data fusion.The results show as follows:(a)among the influencing factors,atmospheric correction uncertainties and geometric misregistration have larger impacts on the fusion results,compared with radiometric bias between the imaging sensors and STF modeling errors;and(b)the machine-learning-based Chla inversion accuracy of the fusion data[R^(2)=0.846 and root mean square error(RMSE)=17.835μg/l]is comparable with that of real Sentinel-2 data(R^(2)=0.856 and RMSE=16.601μg/l),and temporally dense Chla results can be produced with the integrated Sentinel-2 and fusion image datasets.These findings will help to provide guidelines to design STF framework for monitoring aquatic environment of inland waters with remote sensing data.展开更多
Rapidly-advancing microneedle-based bioelectronics integrated with electrical stimulation(ES)therapy exhibit significant potential for improving chronic wound management.Herein,bio-inspired by the serrated structure o...Rapidly-advancing microneedle-based bioelectronics integrated with electrical stimulation(ES)therapy exhibit significant potential for improving chronic wound management.Herein,bio-inspired by the serrated structure of bee-stingers,we developed a temperature-sensitive,two-stage microneedle-based electro active platform(GP-PPy/PLA-MN)featuring rivet-like micros tructures that integrates intelligent,precise drug-releasing,ES-transmission,and real-time wound-assessment monitoring for comprehensive chronic wound-management and diagnostic therapy.The bionic-design mechanically anchors the microneedle beneath the skin's dermis,while GP-PPy/PLA-MN demonstrates versatile therapeutic characteristics,including outstanding biocompatibility,antimicrobial properties,and antimigratory origins.The GP-PPy/PLA-MN enables the sustained release of insulin at body temperature for up to24 hours through the poly-N-isopropyl acrylamide grafted amidated-gelatin-based thermo-sensitive hydrogel at the needle-tip,thereby providing long-term stable blood glucose control.GP-PPy/PLA-MN indicates its potential as a novel bioelectronics-based patch to record the temperature and humidity during the wound-healing process,realizing significant wound diagnosis and real-time wound assessment,and fundamentally facilitating the therapeutic efficacy by supplying solid data to protect the clinical practice.Extensive in vitro and in vivo studies have demonstrated that GP-PPy/PLA-MN can provide effective ES and sustained drug release,thereby promoting chronic wound healing and increasing the wound healing rate by 20%compared to the control group after 14 days of treatment.This innovative approach combines bioelectronics with intelligent drug delivery and microneedling technology to effectively address the critical challenges of chronic wound management,offering promising prospects for precision diagnostics and therapeutic interventions.展开更多
Fault characteristic gas analysis is one of the important methods for monitoring the operating status of power equipment.This study presents the construction of a simulation model for a hollow-core photonic crystal fi...Fault characteristic gas analysis is one of the important methods for monitoring the operating status of power equipment.This study presents the construction of a simulation model for a hollow-core photonic crystal fibre(HC-PCF)-based photothermal spectroscopy gas detection system.The relationship between the phase change of the probe beam and the acetylene concen-tration,pump power,ambient temperature and the modulation frequency is examined.It is achieved by simulating the wavelength modulation of the pump beam and the phase change of the probe beam.The findings demonstrate that there is a linear positive correlation between the pump power and the amplitude of the phase change of the probe beam and the acetylene concentration.For example,acetylene concentration grew from 1 to 10,000 ppm,whereas phase change amplitude increased from 4.71×10^(−4) to 3.70 rad.The pump power grew from 7 to 2000 mW,whereas phase change amplitude increased from 3.73×10^(−4) to 1.01×10^(−1) rad.The phase change of the probe beam is non-linearly and negatively correlated with the ambient temperature.The ambient temperature decreases from 373.15 to 173.15 K,and phase change amplitude increases from 5.05×10^(−3) to 2.15×10^(−2) rad,an enhancement of 4.26 times.The modulation frequency is needed to balance the thermal conduction process in the HC-PCF.In the 1-100 Hz range,the amplitude of the phase change is stable and almost independent of the modulation frequency.In the 100-40,000 Hz range,the amplitude of the phase change decreases rapidly with the increase of the modulation frequency.The results of the paper provide a reference for constructing the HC-PCF-based photothermal spectroscopy gas detection system.展开更多
文摘This study analyzes live facial videos for recognizing nonverbal learning-related facial movements and head poses to discover the learning status of students. First, color and depth facial videos captured by a Kinect are analyzed for face tracking using a three-dimensional （3D） active appearance model （AAM）. Second, the facial feature vector sequences are used to train hidden Markov models （HMMs） to recognize seven learning-related facial movements （smile, blink, frown, shake, nod, yawn, and talk）. The final stage involves the analysis of the facial movement vector sequence to evaluate three status scores （understanding, interaction, and consciousness）, each represents the learning status of a student and is helpful to both teachers and students for improving teaching and learning. Five teaching activities demonstrate that the proposed learning status analysis system promotes the interpersonal communication between teachers and students.
基金National Natural Science Foundation of China(No.51675399)。
文摘Abundant system operation state information is included in the electrical signal of the hydraulic system motor.How to accurately extract and classify the operation information of electrical signal is the key to realize the condition monitoring of hydraulic system.The early fault characteristics of hydraulic gear pump hidden in the motor current signal are weak and difficult to extract by traditional time-frequency analysis.Based on the correlation coefficient and artificial bee colony algorithm(ABC),the parameter optimization of variational mode decomposition(VMD)is realized in this paper.At the same time,the principle of maximum signal correlation coefficient and kurtosis value is adopted to determine the effective intrinsic mode function(IMF).Moreover,the permutation entropy(PE)and root mean square(RMS)of the effective IMF components are input into the deep belief network(DBN-DNN)as high-dimensional feature vectors.The operation state of gear pump is monitored.The results show that the weak characteristics of current signal of gear pump fault are accurately and stably extracted by this method.The running state of gear pump is monitored and the accuracy of gear fault diagnosis is improved.
基金the National Natural Science Foundation of China(NSFC)under No.52308473the National KeyR&DProgram under No.2022YFB2603301the China Postdoctoral Science Foundation funded project(Certificate Number:2023M743895).
文摘Purpose–This study aimed to facilitate a rapid evaluation of track service status and vehicle ride comfort based on car body acceleration.Consequently,a low-cost,data-driven approach was proposed for analyzing speed-related acceleration limits in metro systems.Design/methodology/approach–A portable sensing terminal was developed to realize easy and efficient detection of car body acceleration.Further,field measurements were performed on a 51.95-km metro line.Data from 272 metro sections were tested as a case study,and a quantile regression method was proposed to fit the control limits of the car body acceleration at different speeds using the measured data.Findings–First,the frequency statistics of the measured data in the speed-acceleration dimension indicated that the car body acceleration was primarily concentrated within the constant speed stage,particularly at speeds of 15.4,18.3,and 20.9 m/s.Second,resampling was performed according to the probability density distribution of car body acceleration for different speed domains to achieve data balance.Finally,combined with the traditional linear relationship between speed and acceleration,the statistical relationships between the speed and car body acceleration under different quantiles were determined.We concluded the lateral/vertical quantiles of 0.8989/0.9895,0.9942/0.997,and 0.9998/0.993 as being excellent,good,and qualified control limits,respectively,for the lateral and vertical acceleration of the car body.In addition,regression lines for the speedrelated acceleration limits at other quantiles(0.5,0.75,2s,and 3s)were obtained.Originality/value–The proposed method is expected to serve as a reference for further studies on speedrelated acceleration limits in rail transit systems.
基金supported by the Science and Technology Major Project of Hubei Province,China(grant number 2023BCA003)in part by the Open Fund of Key Laboratory of Urban Land Resources Monitoring and Simulation,Ministry of Natural Resources(grant number KF-2023-08-23)the National Natural Science Foundation of China(grant number 42171375).
文摘The tradeoffs between the spatial and temporal resolutions for the remote sensing instruments limit their capacity to monitor the eutrophic status of inland lakes.Spatiotemporal fusion(STF)provides a cost-effective way to obtain remote sensing data with both high spatial and temporal resolutions by blending multisensor observations.However,remote sensing reflectance(Rrs)over water surface with a relatively low signal-to-noise ratio is prone to be contaminated by large uncertainties in the fusion process.To present a comprehensive analysis on the influence of processing and modeling errors,we conducted an evaluation study to understand the potential,uncertainties,and limitations of using STF for monitoring chlorophyll a(Chla)concentration in an inland eutrophic water(Chaohu Lake,China).Specifically,comparative tests were conducted on the Sentinel-2 and Sentinel-3 image pairs.Three typical STF methods were selected for comparison,i.e.,Fit-FC,spatial and temporal nonlocal filter-based fusion model,and the flexible spatiotemporal data fusion.The results show as follows:(a)among the influencing factors,atmospheric correction uncertainties and geometric misregistration have larger impacts on the fusion results,compared with radiometric bias between the imaging sensors and STF modeling errors;and(b)the machine-learning-based Chla inversion accuracy of the fusion data[R^(2)=0.846 and root mean square error(RMSE)=17.835μg/l]is comparable with that of real Sentinel-2 data(R^(2)=0.856 and RMSE=16.601μg/l),and temporally dense Chla results can be produced with the integrated Sentinel-2 and fusion image datasets.These findings will help to provide guidelines to design STF framework for monitoring aquatic environment of inland waters with remote sensing data.
基金financially supported by the National Natural Science Foun-dation of China(22278257)the Key R&D Program of Shaanxi Province(2024SF-YBXM-586)the Project of Innovation Capability Support Program in Shaanxi Province(2024ZC-KJXX-005)。
文摘Rapidly-advancing microneedle-based bioelectronics integrated with electrical stimulation(ES)therapy exhibit significant potential for improving chronic wound management.Herein,bio-inspired by the serrated structure of bee-stingers,we developed a temperature-sensitive,two-stage microneedle-based electro active platform(GP-PPy/PLA-MN)featuring rivet-like micros tructures that integrates intelligent,precise drug-releasing,ES-transmission,and real-time wound-assessment monitoring for comprehensive chronic wound-management and diagnostic therapy.The bionic-design mechanically anchors the microneedle beneath the skin's dermis,while GP-PPy/PLA-MN demonstrates versatile therapeutic characteristics,including outstanding biocompatibility,antimicrobial properties,and antimigratory origins.The GP-PPy/PLA-MN enables the sustained release of insulin at body temperature for up to24 hours through the poly-N-isopropyl acrylamide grafted amidated-gelatin-based thermo-sensitive hydrogel at the needle-tip,thereby providing long-term stable blood glucose control.GP-PPy/PLA-MN indicates its potential as a novel bioelectronics-based patch to record the temperature and humidity during the wound-healing process,realizing significant wound diagnosis and real-time wound assessment,and fundamentally facilitating the therapeutic efficacy by supplying solid data to protect the clinical practice.Extensive in vitro and in vivo studies have demonstrated that GP-PPy/PLA-MN can provide effective ES and sustained drug release,thereby promoting chronic wound healing and increasing the wound healing rate by 20%compared to the control group after 14 days of treatment.This innovative approach combines bioelectronics with intelligent drug delivery and microneedling technology to effectively address the critical challenges of chronic wound management,offering promising prospects for precision diagnostics and therapeutic interventions.
基金supported by National Natural Science Foundation of China,Grant No.52277161.
文摘Fault characteristic gas analysis is one of the important methods for monitoring the operating status of power equipment.This study presents the construction of a simulation model for a hollow-core photonic crystal fibre(HC-PCF)-based photothermal spectroscopy gas detection system.The relationship between the phase change of the probe beam and the acetylene concen-tration,pump power,ambient temperature and the modulation frequency is examined.It is achieved by simulating the wavelength modulation of the pump beam and the phase change of the probe beam.The findings demonstrate that there is a linear positive correlation between the pump power and the amplitude of the phase change of the probe beam and the acetylene concentration.For example,acetylene concentration grew from 1 to 10,000 ppm,whereas phase change amplitude increased from 4.71×10^(−4) to 3.70 rad.The pump power grew from 7 to 2000 mW,whereas phase change amplitude increased from 3.73×10^(−4) to 1.01×10^(−1) rad.The phase change of the probe beam is non-linearly and negatively correlated with the ambient temperature.The ambient temperature decreases from 373.15 to 173.15 K,and phase change amplitude increases from 5.05×10^(−3) to 2.15×10^(−2) rad,an enhancement of 4.26 times.The modulation frequency is needed to balance the thermal conduction process in the HC-PCF.In the 1-100 Hz range,the amplitude of the phase change is stable and almost independent of the modulation frequency.In the 100-40,000 Hz range,the amplitude of the phase change decreases rapidly with the increase of the modulation frequency.The results of the paper provide a reference for constructing the HC-PCF-based photothermal spectroscopy gas detection system.
