Solar-driven CO_(2) reduction is an efficient way to convert sustainable solar energy and massive CO_(2) to renewable solar fuels,such as CH_(4),HCOOH,HCHO,and CH_(3)OH,etc.Up to now,significant research efforts have ...Solar-driven CO_(2) reduction is an efficient way to convert sustainable solar energy and massive CO_(2) to renewable solar fuels,such as CH_(4),HCOOH,HCHO,and CH_(3)OH,etc.Up to now,significant research efforts have been devoted to exploring the reaction path and developing the photocatalysts.In heterogeneous photocatalysis,among the semiconductor-based photocatalysts,titania(TiO_(2)),as an inexpensive and practically sustainable metal oxides,remains the most extensively studied photocatalyst over the past decades.In this review,we summarize the most recent advances in the solar-driven CO_(2) reduction using TiO_(2)-based photocatalysts,which include the fabrication of heterojunction,surface functional modification,band structure engineering,and morphology design,aiming to improve the CO_(2) conversion efficiency and selectivity to the desired product.Additionally,photoelectrochemical and photothermal approaches are introduced and the fundamental principles to activate and enhance the performance of TiO_(2) for the specific reaction are discussed.The exploration of the solar-driven approaches and discussion on the underlying mechanism allow the comprehensive understanding of CO_(2) photoreduction,that can lead to a rational design and synthesis of TiO_(2)-based photocatalysts.展开更多
In this paper the embedded zerotree wavelet (EZW) method and Huffman coding are proposed to compress infrared (IR) spectra. We found that this technique is much better than others in terms of efficiently coding wavele...In this paper the embedded zerotree wavelet (EZW) method and Huffman coding are proposed to compress infrared (IR) spectra. We found that this technique is much better than others in terms of efficiently coding wavelet coefficients because the zerotree quantization is an effective way of exploiting the self-similarities of wavelet coefficients at various resolutions.展开更多
Applying computer technology to the field of food safety,and how to identify liquor quickly and accurately,is of vital importance and has become a research focus.In this paper,sparse principal component analysis(SPCA)...Applying computer technology to the field of food safety,and how to identify liquor quickly and accurately,is of vital importance and has become a research focus.In this paper,sparse principal component analysis(SPCA)was applied to seek sparse factors of the mid-infrared(MIR)spectra of five famous vintage year Chinese spirits.The results showed while meeting the maximum explained variance,23 sparse principal components(PCs)were selected as features in a support vector machine(SVM)model,which obtained a 97%classification accuracy.By comparison principal component analysis(PCA)selected 10 PCs as features but only achieved an 83%classification accuracy.Although both approaches were better than a direct SVM approach based on the classification results(64%classification accuracy),they also demonstrated the importance of extracting sparse PCs,which captured most important information.The combination of computer technology SPCA and MIR provides a new and convenient method for liquor identification in food safety.展开更多
On-machine tool setting is a pivotal approach in achieving intelligent manufacturing,and laser tool setters have become a crucial component of smart machine tools.Laser tool setters play a crucial role in precisely me...On-machine tool setting is a pivotal approach in achieving intelligent manufacturing,and laser tool setters have become a crucial component of smart machine tools.Laser tool setters play a crucial role in precisely measuring the dimensions of cutting tools during the part machining process,focusing on tool length and diameter.As a measuring instrument,the positions of the laser axis of the laser tool setter need to be accurately calibrated before use.However,in actual calibration scenarios,traditional calibration methods face challenges due to installation errors in the tool setter and geometric errors in the measuring rod.To address this issue,this study proposes a novel calibration method.Initially,the calibration mechanism of the laser beam axis is established.Based on the accurate mathematical model of the laser beam and the measuring rod,and using the polygon clipping algorithm,the mathematical mechanism of the laser tool setter’s work is established.Then,a novel method is introduced to calculate the compensation distance between the laser beam reference point and the rod bottom center point at each moment during calibration.Furthermore,by utilizing the kinematic chain of the tool setter calibration system,a new calibration method is developed to accurately calibrate the position of the laser beam axis in the machine tool coordinate system.Finally,the accuracy of the calibration method is verified through simulation experiments and calibration tests.This method improves the calibration accuracy of the tool setter,and the mathematical model of the laser tool setter can be extended to the measurement of tools,thereby improving the precision of tool measurements.This research significantly improves the efficient production performance of smart machine tools.展开更多
Heart rate is an important metric for determining physical and mental health.In recent years,remote photoplethysmography(rPPG)has been widely used in characterizing physiological signals in human subjects.Currently,re...Heart rate is an important metric for determining physical and mental health.In recent years,remote photoplethysmography(rPPG)has been widely used in characterizing physiological signals in human subjects.Currently,research on non-contact detection of heart rate mainly focuses on the capture and separation of spectral signals from video imagery.However,this method is very sensitive to the movement of the test subject and light intensity variation,and this results in motion artifacts which presents challenges in extracting accurate physiological signals such as heart rate.In this paper,an improved method for rPPG signal preprocessing is proposed.Based on the well known red green blue(RGB)color space,we segmented skin tone in different color spaces and extracted rPPG signals,after which we use a skin segmentation training model based on the luminance component,the blue-difference chroma components,and red-difference chroma components(YCbCr),as well as hue saturation intensity(HSI)color models.In the experimental verification section,we compare the robustness of the signal on different color spaces.In summary,we are experimentally verifying a better image pre-processing method based on real-time rPPG,which results in more precise measurements through the comparative analysis of skin segmentation and signal quality.展开更多
The human visual system is still an important factor in military warfare;military personnel receive training on effective search strategies,and camouflage that can effectively conceal objects and personnel is a key co...The human visual system is still an important factor in military warfare;military personnel receive training on effective search strategies,and camouflage that can effectively conceal objects and personnel is a key component of a successful integrated survivability strategy.Previous methods of camouflage assessment have,amongst others,used psychophysics to generate distinctiveness metrics.However,the population from which the human observers are drawn is often not well defined,or necessarily appropriate.In this experiment we designed a new platform for testing multiple patterns based on a camouflaged object detection task,and investigate whether trained military observers perform better than civilians.We use a two-alternative forced choice paradigm,with participants searching images of woodland for a replica military helmet displaying Olive Green,Multi Terrain Pattern,US Marine Pattern or,as a conspicuous control,UN Peacekeeper Blue.Our data show that there is no difference in detection performance between the two observer groups but that there are clear differences in the effectiveness of the different helmet colour patterns in a temperate woodland environment.We conclude that when tasks involve very short stimulus presentation times,task-specific training has little effect on the success of target detection and thus this paradigm is particularly suitable for robust estimates of camouflage efficacy.展开更多
Smart soft dielectric elastomer actuators(SSDEAs)possess wide applications in soft robotics due to their properties similar to natural muscles,including large deformation ratio,high energy density,and fast response sp...Smart soft dielectric elastomer actuators(SSDEAs)possess wide applications in soft robotics due to their properties similar to natural muscles,including large deformation ratio,high energy density,and fast response speed.However,the complicated asymmetric and rate-dependent hysteresis property,creep property and quadratic input property of the SSDEA pose enormous challenges to its dynamic modeling and motion control.In this paper,first,we construct the dynamic model of the SSDEA by connecting a square module,a one-sided Prandtl–Ishlinskii(OSPI)model and a linear system in series to describe the above properties.The key and innovative aspect of the dynamic modeling lies in cascading the square module in series with the OSPI model to construct the asymmetric hysteresis model.Subsequently,a PI-funnel and inverse hysteresis compensation(PIFIHC)cascade control method of the SSDEA is proposed to actualize its tracking control objective.By performing the inversion operation on the asymmetric hysteresis model,the inverse hysteresis compensation controller(IHCC)is designed to compensate the asymmetric hysteresis property and quadratic input property of the SSDEA.In addition,a PI-funnel controller is designed to cascade with the IHCC to construct the PIFIHC cascade controller to obtain a good tracking performance.Then,the stability analysis of the PIFIHC cascade control system of the SSDEA is performed to theoretically prove that the tracking error can be controlled within the performance funnel and the steady-state error converges to zero.Finally,several practical tracking control experiments of the SSDEA are conducted,and RRMSEs are less than 2.30%for all experiments.These experimental results indicate the effectiveness and feasibility of the proposed PIFIHC cascade control method of the SSDEA.展开更多
To address the problem of high-performance trajectory tracking of a class of uncertain nonlinear systems,this paper proposes a novel proportional-integral-like funnel control(PI-like FC)strategy with rigorous theoreti...To address the problem of high-performance trajectory tracking of a class of uncertain nonlinear systems,this paper proposes a novel proportional-integral-like funnel control(PI-like FC)strategy with rigorous theoretical guarantees.The proposed method retains the prescribed transient performance capabilities inherent to funnel control while introducing an integral action to enhance steady-state accuracy.To mitigate the potential issue caused by integral action,aσ-modification mechanism is incorporated into the control design.The resulting PI-like funnel controller operates without requiring precise system models or detailed knowledge of the nonlinearities,thereby ensuring simplicity in design,ease of implementation,and broad applicability.Rigorous analysis establishes the closed-loop stability and guarantees that the tracking error remains strictly confined within predefined performance bounds.Simulation studies further validate the effectiveness and robustness of the proposed approach in achieving accurate trajectory tracking for uncertain nonlinear systems.展开更多
The stability of matter is a historical problem that tackles the linearity of the bulk energy with the total number of particles M.The classical and quantum variants have been proved using mostly Coulomb interaction b...The stability of matter is a historical problem that tackles the linearity of the bulk energy with the total number of particles M.The classical and quantum variants have been proved using mostly Coulomb interaction between electrons and nuclei,either fixed or submitted to thermal fluctuation.The classical dipole–dipole interaction is addressed here as the sole energy on regular tilings.We prove that the system on any regular(periodic)grid is always stable.The aperiodic or quasicrystal instance is conjectured and numerically illustrated for the particular cases of the Penrose P2 and the recently discovered hat monotiles.展开更多
文摘Solar-driven CO_(2) reduction is an efficient way to convert sustainable solar energy and massive CO_(2) to renewable solar fuels,such as CH_(4),HCOOH,HCHO,and CH_(3)OH,etc.Up to now,significant research efforts have been devoted to exploring the reaction path and developing the photocatalysts.In heterogeneous photocatalysis,among the semiconductor-based photocatalysts,titania(TiO_(2)),as an inexpensive and practically sustainable metal oxides,remains the most extensively studied photocatalyst over the past decades.In this review,we summarize the most recent advances in the solar-driven CO_(2) reduction using TiO_(2)-based photocatalysts,which include the fabrication of heterojunction,surface functional modification,band structure engineering,and morphology design,aiming to improve the CO_(2) conversion efficiency and selectivity to the desired product.Additionally,photoelectrochemical and photothermal approaches are introduced and the fundamental principles to activate and enhance the performance of TiO_(2) for the specific reaction are discussed.The exploration of the solar-driven approaches and discussion on the underlying mechanism allow the comprehensive understanding of CO_(2) photoreduction,that can lead to a rational design and synthesis of TiO_(2)-based photocatalysts.
基金supported by the National Natural Science Foundmion of China(No.29877016).
文摘In this paper the embedded zerotree wavelet (EZW) method and Huffman coding are proposed to compress infrared (IR) spectra. We found that this technique is much better than others in terms of efficiently coding wavelet coefficients because the zerotree quantization is an effective way of exploiting the self-similarities of wavelet coefficients at various resolutions.
基金This work was financially supported by the National Nature Science Foundation of China(Grant Number:61962010).
文摘Applying computer technology to the field of food safety,and how to identify liquor quickly and accurately,is of vital importance and has become a research focus.In this paper,sparse principal component analysis(SPCA)was applied to seek sparse factors of the mid-infrared(MIR)spectra of five famous vintage year Chinese spirits.The results showed while meeting the maximum explained variance,23 sparse principal components(PCs)were selected as features in a support vector machine(SVM)model,which obtained a 97%classification accuracy.By comparison principal component analysis(PCA)selected 10 PCs as features but only achieved an 83%classification accuracy.Although both approaches were better than a direct SVM approach based on the classification results(64%classification accuracy),they also demonstrated the importance of extracting sparse PCs,which captured most important information.The combination of computer technology SPCA and MIR provides a new and convenient method for liquor identification in food safety.
文摘On-machine tool setting is a pivotal approach in achieving intelligent manufacturing,and laser tool setters have become a crucial component of smart machine tools.Laser tool setters play a crucial role in precisely measuring the dimensions of cutting tools during the part machining process,focusing on tool length and diameter.As a measuring instrument,the positions of the laser axis of the laser tool setter need to be accurately calibrated before use.However,in actual calibration scenarios,traditional calibration methods face challenges due to installation errors in the tool setter and geometric errors in the measuring rod.To address this issue,this study proposes a novel calibration method.Initially,the calibration mechanism of the laser beam axis is established.Based on the accurate mathematical model of the laser beam and the measuring rod,and using the polygon clipping algorithm,the mathematical mechanism of the laser tool setter’s work is established.Then,a novel method is introduced to calculate the compensation distance between the laser beam reference point and the rod bottom center point at each moment during calibration.Furthermore,by utilizing the kinematic chain of the tool setter calibration system,a new calibration method is developed to accurately calibrate the position of the laser beam axis in the machine tool coordinate system.Finally,the accuracy of the calibration method is verified through simulation experiments and calibration tests.This method improves the calibration accuracy of the tool setter,and the mathematical model of the laser tool setter can be extended to the measurement of tools,thereby improving the precision of tool measurements.This research significantly improves the efficient production performance of smart machine tools.
基金This work was financially supported by the National Nature Science Foundation of China(Grant Number:61962010).
文摘Heart rate is an important metric for determining physical and mental health.In recent years,remote photoplethysmography(rPPG)has been widely used in characterizing physiological signals in human subjects.Currently,research on non-contact detection of heart rate mainly focuses on the capture and separation of spectral signals from video imagery.However,this method is very sensitive to the movement of the test subject and light intensity variation,and this results in motion artifacts which presents challenges in extracting accurate physiological signals such as heart rate.In this paper,an improved method for rPPG signal preprocessing is proposed.Based on the well known red green blue(RGB)color space,we segmented skin tone in different color spaces and extracted rPPG signals,after which we use a skin segmentation training model based on the luminance component,the blue-difference chroma components,and red-difference chroma components(YCbCr),as well as hue saturation intensity(HSI)color models.In the experimental verification section,we compare the robustness of the signal on different color spaces.In summary,we are experimentally verifying a better image pre-processing method based on real-time rPPG,which results in more precise measurements through the comparative analysis of skin segmentation and signal quality.
基金This work was supported by QinetiQ(contract number UoBMASTSUB/1000067064)and the EPSRC(grant number EP/M006905/1).
文摘The human visual system is still an important factor in military warfare;military personnel receive training on effective search strategies,and camouflage that can effectively conceal objects and personnel is a key component of a successful integrated survivability strategy.Previous methods of camouflage assessment have,amongst others,used psychophysics to generate distinctiveness metrics.However,the population from which the human observers are drawn is often not well defined,or necessarily appropriate.In this experiment we designed a new platform for testing multiple patterns based on a camouflaged object detection task,and investigate whether trained military observers perform better than civilians.We use a two-alternative forced choice paradigm,with participants searching images of woodland for a replica military helmet displaying Olive Green,Multi Terrain Pattern,US Marine Pattern or,as a conspicuous control,UN Peacekeeper Blue.Our data show that there is no difference in detection performance between the two observer groups but that there are clear differences in the effectiveness of the different helmet colour patterns in a temperate woodland environment.We conclude that when tasks involve very short stimulus presentation times,task-specific training has little effect on the success of target detection and thus this paradigm is particularly suitable for robust estimates of camouflage efficacy.
基金supported by the National Natural Science Foundation of China(No.62273316)the 111 project(No.B17040)and the Program of China Scholarship Council(No.202206410064).
文摘Smart soft dielectric elastomer actuators(SSDEAs)possess wide applications in soft robotics due to their properties similar to natural muscles,including large deformation ratio,high energy density,and fast response speed.However,the complicated asymmetric and rate-dependent hysteresis property,creep property and quadratic input property of the SSDEA pose enormous challenges to its dynamic modeling and motion control.In this paper,first,we construct the dynamic model of the SSDEA by connecting a square module,a one-sided Prandtl–Ishlinskii(OSPI)model and a linear system in series to describe the above properties.The key and innovative aspect of the dynamic modeling lies in cascading the square module in series with the OSPI model to construct the asymmetric hysteresis model.Subsequently,a PI-funnel and inverse hysteresis compensation(PIFIHC)cascade control method of the SSDEA is proposed to actualize its tracking control objective.By performing the inversion operation on the asymmetric hysteresis model,the inverse hysteresis compensation controller(IHCC)is designed to compensate the asymmetric hysteresis property and quadratic input property of the SSDEA.In addition,a PI-funnel controller is designed to cascade with the IHCC to construct the PIFIHC cascade controller to obtain a good tracking performance.Then,the stability analysis of the PIFIHC cascade control system of the SSDEA is performed to theoretically prove that the tracking error can be controlled within the performance funnel and the steady-state error converges to zero.Finally,several practical tracking control experiments of the SSDEA are conducted,and RRMSEs are less than 2.30%for all experiments.These experimental results indicate the effectiveness and feasibility of the proposed PIFIHC cascade control method of the SSDEA.
基金supported by the National Natural Science Foundation of China(Grant Nos.62173097,62121004,U2013601)the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022A515011239,2024B1515120004)the Local Innovative and Research Team Project of Guangdong Special Support Program(Grant No.2019BT02X353)。
文摘To address the problem of high-performance trajectory tracking of a class of uncertain nonlinear systems,this paper proposes a novel proportional-integral-like funnel control(PI-like FC)strategy with rigorous theoretical guarantees.The proposed method retains the prescribed transient performance capabilities inherent to funnel control while introducing an integral action to enhance steady-state accuracy.To mitigate the potential issue caused by integral action,aσ-modification mechanism is incorporated into the control design.The resulting PI-like funnel controller operates without requiring precise system models or detailed knowledge of the nonlinearities,thereby ensuring simplicity in design,ease of implementation,and broad applicability.Rigorous analysis establishes the closed-loop stability and guarantees that the tracking error remains strictly confined within predefined performance bounds.Simulation studies further validate the effectiveness and robustness of the proposed approach in achieving accurate trajectory tracking for uncertain nonlinear systems.
基金J.J.C.and J.B.thank grant PID2020-118317GB-I00 funded by MICIU/AEI/10.13039/501100011033.
文摘The stability of matter is a historical problem that tackles the linearity of the bulk energy with the total number of particles M.The classical and quantum variants have been proved using mostly Coulomb interaction between electrons and nuclei,either fixed or submitted to thermal fluctuation.The classical dipole–dipole interaction is addressed here as the sole energy on regular tilings.We prove that the system on any regular(periodic)grid is always stable.The aperiodic or quasicrystal instance is conjectured and numerically illustrated for the particular cases of the Penrose P2 and the recently discovered hat monotiles.
