The Korea peninsula extends southward from the eastern end of the Asian continent. It is divided just slightly north of the 38th parallel. The peninsula is roughly 1020 km(612 miles) long and 175 km( 105 miles) wide a...The Korea peninsula extends southward from the eastern end of the Asian continent. It is divided just slightly north of the 38th parallel. The peninsula is roughly 1020 km(612 miles) long and 175 km( 105 miles) wide at its narrowest point.展开更多
SAMR Vice-Minister and SAC Administrator Tian Shihong as the Leader of the Chinese delegation attended the 109th ISO Council Meeting in Costa Rica and subsequently the fourth meeting of the China-UK Standardization Co...SAMR Vice-Minister and SAC Administrator Tian Shihong as the Leader of the Chinese delegation attended the 109th ISO Council Meeting in Costa Rica and subsequently the fourth meeting of the China-UK Standardization Cooperati on Commissi on in the UK from June 10 to 17.展开更多
In recent years,three-dimensional reconstruction technologies that employ multiple cameras have continued to evolve significantly,enabling remote collaboration among users in extended Reality(XR)environments.In additi...In recent years,three-dimensional reconstruction technologies that employ multiple cameras have continued to evolve significantly,enabling remote collaboration among users in extended Reality(XR)environments.In addition,methods for deploying multiple cameras for motion capture of users(e.g.,performers)are widely used in computer graphics.As the need to minimize and optimize the number of cameras grows to reduce costs,various technologies and research approaches focused on Optimal Camera Placement(OCP)are continually being proposed.However,as most existing studies assume homogeneous camera setups,there is a growing demand for studies on heterogeneous camera setups.For instance,technical demands keep emerging in scenarios with minimal camera configurations,especially regarding cost factors,the physical placement of cameras given the spatial structure,and image capture strategies for heterogeneous cameras,such as high-resolution RGB cameras and depth cameras.In this study,we propose a pre-visualization and simulation method for the optimal placement of heterogeneous cameras in XR environments,accounting for both the specifications of heterogeneous cameras(e.g.,field of view)and the physical configuration(e.g.,wall configuration)in real-world spaces.The proposed method performs a visibility analysis of cameras by considering each camera’s field-of-view volume,resolution,and unique characteristics,along with physicalspace constraints.This approach enables the optimal position and rotation of each camera to be recommended,along with the minimum number of cameras required.In the results of our study conducted in heterogeneous camera combinations,the proposed method achieved 81.7%~82.7%coverage of the target visual information using only 2~3 cameras.In contrast,single(or homogeneous)-typed cameras were required to use 11 cameras for 81.6%coverage.Accordingly,we found that camera deployment resources can be reduced with the proposed approaches.展开更多
Molecular tailoring of self-assembled hole-transporting monolayers(SAMs)has been proven as an efficient approach for improving the device performance of inverted perovskite solar cells.Herein,a novel SAM with extended...Molecular tailoring of self-assembled hole-transporting monolayers(SAMs)has been proven as an efficient approach for improving the device performance of inverted perovskite solar cells.Herein,a novel SAM with extended conjugation is designed and synthesized,named NaPh-4PACz.Compared to Ph-4PACz,NaPh-4PACz exhibits a larger adsorption energy with the ITO substrate,enabling the formation of a more uniform and dense film,thereby preventing direct contact between the perovskite and ITO.Additionally,NaPh-4PACz also has a stronger interaction with the perovskite,which can reduce buried interface defects and suppress non-radiative recombination.Consequently,NaPh-4PACz-based devices achieved a power conversion efficiency of 25.48%due to their interfacial“adhesive”ability.Importantly,the stability of the NaPh-4PACz-based devices was significantly improved.展开更多
AIM:To compare the visual outcomes between bilateral implantation of Tecnis ZXR00 extended depth-of-focus(EDOF)intraocular lenses(IOLs)and mixed implantation of Tecnis ZXR00(EDOF)with Tecnis ZMB00(bifocal)IOLs.METHODS...AIM:To compare the visual outcomes between bilateral implantation of Tecnis ZXR00 extended depth-of-focus(EDOF)intraocular lenses(IOLs)and mixed implantation of Tecnis ZXR00(EDOF)with Tecnis ZMB00(bifocal)IOLs.METHODS:This postoperative cross-sectional study enrolled patients who underwent phacoemulsification combined with IOL implantation.Patients were divided into two groups:the bilateral ZXR00 group(ZXR00-only group)and the mixed IOL group(ZXR00+ZMB00 group).Primary outcome measures included uncorrected and corrected distance visual acuity(UDVA,CDVA),uncorrected and distance-corrected near visual acuity(UNVA,DCNVA),uncorrected and distance-corrected intermediate visual acuity(UIVA,DCIVA),and defocus curves.Secondary outcome measures were visual quality,spectacle independence,patient satisfaction,photic phenomena,and stereopsis.RESULTS:A total of 47 patients(94 eyes)were included,with 26 patients(11 males,15 females)in the ZXR00-only group(mean age:62.73±7.24y)and 21 patients(7 males,14 females)in the mixed group(mean age:65.71±9.16y).There was no statistically significant difference in age between the two groups(P=0.218).The mixed group showed significantly better binocular DCNVA compared to the ZXR00-only group(P=0.002).Defocus curve analysis revealed that the mixed group exhibited superior performance at−2.5 to−4.0 D but inferior performance at−0.5 and−1.5 D.Near stereoacuity was significantly poorer in the mixed group(Randot:5.589±0.744 vs 6.240±0.394 ln arcsec;Contour:4.966±0.973 vs 5.740±0.833 ln arcsec;both P<0.01).Both groups achieved high levels of spectacle independence and patient satisfaction,with no significant differences in photic phenomena or questionnaire scores.CONCLUSION:Mixed implantation of EDOF and bifocal IOLs improve near visual acuity but may compromise near stereopsis.This approach provides a viable option for patients prioritizing near vision;however,caution is recommended for individuals requiring fine stereoscopic vision for daily or professional tasks.展开更多
The Recommendations of the Central Committee of the Communist Party of China for Formulating the 15th Five-Year Plan for National Economic and Social Development call for inspiring the cultural creativity of our entir...The Recommendations of the Central Committee of the Communist Party of China for Formulating the 15th Five-Year Plan for National Economic and Social Development call for inspiring the cultural creativity of our entire nation,further integrating culture and technology,empowering cultural development with digital and intelligent technologies,and shifting to an IT-based development model,while working to foster new forms of cultural business,and extending the reach and appeal of Chinese civilization.展开更多
Covalent organic frameworks(COFs)are an emerging class of porous crystalline materials formed by the precise assembly of organic molecular building blocks into extended periodic structures via strong covalent bonds.Th...Covalent organic frameworks(COFs)are an emerging class of porous crystalline materials formed by the precise assembly of organic molecular building blocks into extended periodic structures via strong covalent bonds.They feature well-defined pore structure,high specific surface area,and tunable physicochemical properties,endowing them with broad application prospects in gas storage,molecular separation.展开更多
In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypro...In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.展开更多
The concept of emissivity has been with the scientific and engineering world since Planck formulated his blackbody radiation law more than a century ago.Nevertheless,emissivity is an elusive concept even for ex⁃perts....The concept of emissivity has been with the scientific and engineering world since Planck formulated his blackbody radiation law more than a century ago.Nevertheless,emissivity is an elusive concept even for ex⁃perts.It is a vague and fuzzy concept for the wider community of engineers.The importance of remote sensing of temperature by measuring IR radiation has been recognized in a wide range of industrial,medical,and environ⁃mental uses.One of the major sources of errors in IR radiometry is the emissivity of the surface being measured.In real experiments,emissivity may be influenced by many factors:surface texture,spectral properties,oxida⁃tion,and aging of surfaces.While commercial blackbodies are prevalent,the much-needed grey bodies with a known emissivity,are unavailable.This study describes how to achieve a calibrated and stable emissivity with a blackbody,a perforated screen,and a reliable and linear novel IR thermal sensor,18 dubbed TMOS.The Digital TMOS is now a low-cost commercial product,it requires low power,and it has a small form factor.The method⁃ology is based on two-color measurements,with two different optical filters,with selected wavelengths conform⁃ing to the grey body definition of the use case under study.With a photochemically etched perforated screen,the effective emissivity of the screen is simply the hole density area of the surface area that emits according to the blackbody temperature radiation.The concept is illustrated with ray tracing simulations,which demonstrate the approach.Measured results are reported.展开更多
Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influenci...Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influencing factors of SM in these areas remains insufficient.This study investigated the spatiotemporal variations and influencing factors of SM in arid and semi-arid areas of China by utilizing the extended triple collation(ETC),Mann-Kendall test,Theil-Sen estimator,ridge regression analysis,and other relevant methods.The following findings were obtained:(1)at the pixel scale,the long-term monthly SM data from the European Space Agency Climate Change Initiative(ESA CCI)exhibited the highest correlation coefficient of 0.794 and the lowest root mean square error(RMSE)of 0.014 m^(3)/m^(3);(2)from 2000 to 2022,the study area experienced significant increase in annual average SM,with a rate of 0.408×10^(-3)m^(3)/(m^(3)•a).Moreover,higher altitudes showed a notable upward trend,with SM increasing rates at 0.210×10^(-3)m^(3)/(m^(3)•a)between 1000 and 2000 m,0.530×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m,and 0.760×10^(-3)m^(3)/(m^(3)•a)at altitudes above 4000 m;(3)land surface temperature(LST),root zone soil moisture(RSM)(10-40 cm depth),and normalized difference vegetation index(NDVI)were identified as the primary factors influencing annual average SM,which accounted for 34.37%,24.16%,and 22.64%relative contributions,respectively;and(4)absolute contribution of LST was more significant in subareas at higher altitudes,with average absolute contributions of 0.800×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m and 0.500×10^(-2) m^(3)/(m^(3)•a)above 4000 m.This study reveals the spatiotemporal variations and main influencing factors of SM in Chinese arid and semi-arid areas,highlighting the more pronounced absolute contribution of LST to SM in high-altitude areas,providing valuable insights for ecological research and water resource management in these areas.展开更多
Amid the escalating plastic pollution issue, the development of biodegradable and recyclable polymeric materials has become a focus within the scientific community. Chain extenders, which are an important class of com...Amid the escalating plastic pollution issue, the development of biodegradable and recyclable polymeric materials has become a focus within the scientific community. Chain extenders, which are an important class of compounds, facilitate the elongation of polymer chains through reactive functional groups, thereby enhancing the performance of the materials. Epoxy-based chain extenders, due to their cost-effectiveness, low toxicity, high reaction efficiency, and effective reactivity with hydroxyl and carboxyl groups, have emerged as a promising class of chain extenders. This manuscript comprehensively elaborates on the varieties, structural characteristics, and performance of chain extenders, the challenges they face, and the methods for their modification. Special emphasis is placed on the application of epoxy-based chain extenders in biodegradable polymers, such as polylactic acid (PLA), and their subsequent influence on the structural and performance properties of these materials.展开更多
Phantom limb pain(PLP)is not only a physical pain experience but also poses a significant challenge to mental health and quality of life.Currently,the mechanism of PLP treatment is still unclear,and there are many met...Phantom limb pain(PLP)is not only a physical pain experience but also poses a significant challenge to mental health and quality of life.Currently,the mechanism of PLP treatment is still unclear,and there are many methods with varying effects.This article starts with the application research of extended reality technology in PLP treatment,through describing the application of its branch technologies(virtual reality,augmented reality,and mixed reality technology),to lay the foundation for subsequent research,in the hope of finding advanced and effective treatment methods,and providing a basis for future product transformation.展开更多
In this paper,an advanced satellite navigation filter design,referred to as the Variational Bayesian Maximum Correntropy Extended Kalman Filter(VBMCEKF),is introduced to enhance robustness and adaptability in scenario...In this paper,an advanced satellite navigation filter design,referred to as the Variational Bayesian Maximum Correntropy Extended Kalman Filter(VBMCEKF),is introduced to enhance robustness and adaptability in scenarios with non-Gaussian noise and heavy-tailed outliers.The proposed design modifies the extended Kalman filter(EKF)for the global navigation satellite system(GNSS),integrating the maximum correntropy criterion(MCC)and the variational Bayesian(VB)method.This adaptive algorithm effectively reduces non-line-of-sight(NLOS)reception contamination and improves estimation accuracy,particularly in time-varying GNSS measurements.Experimental results show that the proposed method significantly outperforms conventional approaches in estimation accuracy under heavy-tailed outliers and non-Gaussian noise.By combining MCC with VB approximation for real-time noise covariance estimation using fixed-point iteration,the VBMCEKF achieves superior filtering performance in challenging GNSS conditions.The method’s adaptability and precision make it ideal for improving satellite navigation performance in stochastic environments.展开更多
The output feedback active disturbance rejection control of a valve-controlled cylinder electro-hydraulic servo system is investigated in this paper.First,a comprehensive nonlinear mathematical model that encompasses ...The output feedback active disturbance rejection control of a valve-controlled cylinder electro-hydraulic servo system is investigated in this paper.First,a comprehensive nonlinear mathematical model that encompasses both matched and mismatched disturbances is formulated.Due to the fact that only position information can be measured,a linear Extended State Observer(ESO)is introduced to estimate unknown states and matched disturbances,while a dedicated disturbance observer is constructed to estimate mismatched disturbances.Different from the traditional observer results,the design of the disturbance observer used in this study is carried out under the constraint of output feedback.Furthermore,an output feedback nonlinear controller is proposed leveraging the aforementioned observers to achieve accurate trajectory tracking.To mitigate the inherent differential explosion problem of the traditional backstepping framework,a finite-time stable command filter is incorporated.Simultaneously,considering transient filtering errors,a set of error compensation signals are designed to counter their negative impact effectively.Theoretical analysis affirms that the proposed control strategy ensures the boundedness of all signals within the closed-loop system.Additionally,under the specific condition of only time-invariant disturbances in the system,the conclusion of asymptotic stability is established.Finally,the algorithm’s efficacy is validated through comparative experiments.展开更多
文摘The Korea peninsula extends southward from the eastern end of the Asian continent. It is divided just slightly north of the 38th parallel. The peninsula is roughly 1020 km(612 miles) long and 175 km( 105 miles) wide at its narrowest point.
文摘SAMR Vice-Minister and SAC Administrator Tian Shihong as the Leader of the Chinese delegation attended the 109th ISO Council Meeting in Costa Rica and subsequently the fourth meeting of the China-UK Standardization Cooperati on Commissi on in the UK from June 10 to 17.
文摘Anewtechnology──lasershockprocessing(LSP)forimprovingthemechanicalpropertiesofmetals,especiallyfatiguelife,ispresented.Themechanismofstresswavegeneratedbylasershockingisdescribed,andthestresswaveismeasuredwithPVDFtransducer.Ahigh-powerdensity,neodyrnium-glasslaserwasusedforshockingaluminumalloy,thefatiguelifeofaluminumalloywasincreasedgreatly.With95%confidence,thefatiguelifeofLSPspecimensis5.4to14.5timeslongerthantheunshockedSpecimensLaser s
基金supported by the 2024 Research Fund of University of Ulsan.
文摘In recent years,three-dimensional reconstruction technologies that employ multiple cameras have continued to evolve significantly,enabling remote collaboration among users in extended Reality(XR)environments.In addition,methods for deploying multiple cameras for motion capture of users(e.g.,performers)are widely used in computer graphics.As the need to minimize and optimize the number of cameras grows to reduce costs,various technologies and research approaches focused on Optimal Camera Placement(OCP)are continually being proposed.However,as most existing studies assume homogeneous camera setups,there is a growing demand for studies on heterogeneous camera setups.For instance,technical demands keep emerging in scenarios with minimal camera configurations,especially regarding cost factors,the physical placement of cameras given the spatial structure,and image capture strategies for heterogeneous cameras,such as high-resolution RGB cameras and depth cameras.In this study,we propose a pre-visualization and simulation method for the optimal placement of heterogeneous cameras in XR environments,accounting for both the specifications of heterogeneous cameras(e.g.,field of view)and the physical configuration(e.g.,wall configuration)in real-world spaces.The proposed method performs a visibility analysis of cameras by considering each camera’s field-of-view volume,resolution,and unique characteristics,along with physicalspace constraints.This approach enables the optimal position and rotation of each camera to be recommended,along with the minimum number of cameras required.In the results of our study conducted in heterogeneous camera combinations,the proposed method achieved 81.7%~82.7%coverage of the target visual information using only 2~3 cameras.In contrast,single(or homogeneous)-typed cameras were required to use 11 cameras for 81.6%coverage.Accordingly,we found that camera deployment resources can be reduced with the proposed approaches.
基金supported by the National Natural Science Foundation of China(61904053,22279033)the National Key Research and Development Program of China(2023YFB4204502)+2 种基金the 111 Project(B16016)the Fundamental Research Funds for the Central Universities(2025MS043)the Special Foundation for Carbon Peak Carbon Neutralization Technology Innovation Program of Jiangsu Province(BE2022026).
文摘Molecular tailoring of self-assembled hole-transporting monolayers(SAMs)has been proven as an efficient approach for improving the device performance of inverted perovskite solar cells.Herein,a novel SAM with extended conjugation is designed and synthesized,named NaPh-4PACz.Compared to Ph-4PACz,NaPh-4PACz exhibits a larger adsorption energy with the ITO substrate,enabling the formation of a more uniform and dense film,thereby preventing direct contact between the perovskite and ITO.Additionally,NaPh-4PACz also has a stronger interaction with the perovskite,which can reduce buried interface defects and suppress non-radiative recombination.Consequently,NaPh-4PACz-based devices achieved a power conversion efficiency of 25.48%due to their interfacial“adhesive”ability.Importantly,the stability of the NaPh-4PACz-based devices was significantly improved.
文摘AIM:To compare the visual outcomes between bilateral implantation of Tecnis ZXR00 extended depth-of-focus(EDOF)intraocular lenses(IOLs)and mixed implantation of Tecnis ZXR00(EDOF)with Tecnis ZMB00(bifocal)IOLs.METHODS:This postoperative cross-sectional study enrolled patients who underwent phacoemulsification combined with IOL implantation.Patients were divided into two groups:the bilateral ZXR00 group(ZXR00-only group)and the mixed IOL group(ZXR00+ZMB00 group).Primary outcome measures included uncorrected and corrected distance visual acuity(UDVA,CDVA),uncorrected and distance-corrected near visual acuity(UNVA,DCNVA),uncorrected and distance-corrected intermediate visual acuity(UIVA,DCIVA),and defocus curves.Secondary outcome measures were visual quality,spectacle independence,patient satisfaction,photic phenomena,and stereopsis.RESULTS:A total of 47 patients(94 eyes)were included,with 26 patients(11 males,15 females)in the ZXR00-only group(mean age:62.73±7.24y)and 21 patients(7 males,14 females)in the mixed group(mean age:65.71±9.16y).There was no statistically significant difference in age between the two groups(P=0.218).The mixed group showed significantly better binocular DCNVA compared to the ZXR00-only group(P=0.002).Defocus curve analysis revealed that the mixed group exhibited superior performance at−2.5 to−4.0 D but inferior performance at−0.5 and−1.5 D.Near stereoacuity was significantly poorer in the mixed group(Randot:5.589±0.744 vs 6.240±0.394 ln arcsec;Contour:4.966±0.973 vs 5.740±0.833 ln arcsec;both P<0.01).Both groups achieved high levels of spectacle independence and patient satisfaction,with no significant differences in photic phenomena or questionnaire scores.CONCLUSION:Mixed implantation of EDOF and bifocal IOLs improve near visual acuity but may compromise near stereopsis.This approach provides a viable option for patients prioritizing near vision;however,caution is recommended for individuals requiring fine stereoscopic vision for daily or professional tasks.
文摘The Recommendations of the Central Committee of the Communist Party of China for Formulating the 15th Five-Year Plan for National Economic and Social Development call for inspiring the cultural creativity of our entire nation,further integrating culture and technology,empowering cultural development with digital and intelligent technologies,and shifting to an IT-based development model,while working to foster new forms of cultural business,and extending the reach and appeal of Chinese civilization.
文摘Covalent organic frameworks(COFs)are an emerging class of porous crystalline materials formed by the precise assembly of organic molecular building blocks into extended periodic structures via strong covalent bonds.They feature well-defined pore structure,high specific surface area,and tunable physicochemical properties,endowing them with broad application prospects in gas storage,molecular separation.
文摘In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.
文摘The concept of emissivity has been with the scientific and engineering world since Planck formulated his blackbody radiation law more than a century ago.Nevertheless,emissivity is an elusive concept even for ex⁃perts.It is a vague and fuzzy concept for the wider community of engineers.The importance of remote sensing of temperature by measuring IR radiation has been recognized in a wide range of industrial,medical,and environ⁃mental uses.One of the major sources of errors in IR radiometry is the emissivity of the surface being measured.In real experiments,emissivity may be influenced by many factors:surface texture,spectral properties,oxida⁃tion,and aging of surfaces.While commercial blackbodies are prevalent,the much-needed grey bodies with a known emissivity,are unavailable.This study describes how to achieve a calibrated and stable emissivity with a blackbody,a perforated screen,and a reliable and linear novel IR thermal sensor,18 dubbed TMOS.The Digital TMOS is now a low-cost commercial product,it requires low power,and it has a small form factor.The method⁃ology is based on two-color measurements,with two different optical filters,with selected wavelengths conform⁃ing to the grey body definition of the use case under study.With a photochemically etched perforated screen,the effective emissivity of the screen is simply the hole density area of the surface area that emits according to the blackbody temperature radiation.The concept is illustrated with ray tracing simulations,which demonstrate the approach.Measured results are reported.
基金supported by the Natural Science Foundation of Henan Province(252300421290)the National Natural Science Foundation of China(41771438)+1 种基金the Program for Innovative Research Team(in Science and Technology)of Henan University(22IRTSTHN010)the Postgraduate Education Reform and Quality Improvement Project of Henan Province(HNYJS2020JD14).
文摘Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influencing factors of SM in these areas remains insufficient.This study investigated the spatiotemporal variations and influencing factors of SM in arid and semi-arid areas of China by utilizing the extended triple collation(ETC),Mann-Kendall test,Theil-Sen estimator,ridge regression analysis,and other relevant methods.The following findings were obtained:(1)at the pixel scale,the long-term monthly SM data from the European Space Agency Climate Change Initiative(ESA CCI)exhibited the highest correlation coefficient of 0.794 and the lowest root mean square error(RMSE)of 0.014 m^(3)/m^(3);(2)from 2000 to 2022,the study area experienced significant increase in annual average SM,with a rate of 0.408×10^(-3)m^(3)/(m^(3)•a).Moreover,higher altitudes showed a notable upward trend,with SM increasing rates at 0.210×10^(-3)m^(3)/(m^(3)•a)between 1000 and 2000 m,0.530×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m,and 0.760×10^(-3)m^(3)/(m^(3)•a)at altitudes above 4000 m;(3)land surface temperature(LST),root zone soil moisture(RSM)(10-40 cm depth),and normalized difference vegetation index(NDVI)were identified as the primary factors influencing annual average SM,which accounted for 34.37%,24.16%,and 22.64%relative contributions,respectively;and(4)absolute contribution of LST was more significant in subareas at higher altitudes,with average absolute contributions of 0.800×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m and 0.500×10^(-2) m^(3)/(m^(3)•a)above 4000 m.This study reveals the spatiotemporal variations and main influencing factors of SM in Chinese arid and semi-arid areas,highlighting the more pronounced absolute contribution of LST to SM in high-altitude areas,providing valuable insights for ecological research and water resource management in these areas.
文摘Amid the escalating plastic pollution issue, the development of biodegradable and recyclable polymeric materials has become a focus within the scientific community. Chain extenders, which are an important class of compounds, facilitate the elongation of polymer chains through reactive functional groups, thereby enhancing the performance of the materials. Epoxy-based chain extenders, due to their cost-effectiveness, low toxicity, high reaction efficiency, and effective reactivity with hydroxyl and carboxyl groups, have emerged as a promising class of chain extenders. This manuscript comprehensively elaborates on the varieties, structural characteristics, and performance of chain extenders, the challenges they face, and the methods for their modification. Special emphasis is placed on the application of epoxy-based chain extenders in biodegradable polymers, such as polylactic acid (PLA), and their subsequent influence on the structural and performance properties of these materials.
文摘Phantom limb pain(PLP)is not only a physical pain experience but also poses a significant challenge to mental health and quality of life.Currently,the mechanism of PLP treatment is still unclear,and there are many methods with varying effects.This article starts with the application research of extended reality technology in PLP treatment,through describing the application of its branch technologies(virtual reality,augmented reality,and mixed reality technology),to lay the foundation for subsequent research,in the hope of finding advanced and effective treatment methods,and providing a basis for future product transformation.
基金supported by the National Science and Technology Council,Taiwan under grants NSTC 111-2221-E-019-047 and NSTC 112-2221-E-019-030.
文摘In this paper,an advanced satellite navigation filter design,referred to as the Variational Bayesian Maximum Correntropy Extended Kalman Filter(VBMCEKF),is introduced to enhance robustness and adaptability in scenarios with non-Gaussian noise and heavy-tailed outliers.The proposed design modifies the extended Kalman filter(EKF)for the global navigation satellite system(GNSS),integrating the maximum correntropy criterion(MCC)and the variational Bayesian(VB)method.This adaptive algorithm effectively reduces non-line-of-sight(NLOS)reception contamination and improves estimation accuracy,particularly in time-varying GNSS measurements.Experimental results show that the proposed method significantly outperforms conventional approaches in estimation accuracy under heavy-tailed outliers and non-Gaussian noise.By combining MCC with VB approximation for real-time noise covariance estimation using fixed-point iteration,the VBMCEKF achieves superior filtering performance in challenging GNSS conditions.The method’s adaptability and precision make it ideal for improving satellite navigation performance in stochastic environments.
基金supported by the National Key R&D Program of China(No.2021YFB2011300)the Special Funds Project for the Transformation of Scientific and Technological Achievements of Jiangsu Province,China(No.BA2023039)+1 种基金the National Natural Science Foundation of China(No.52075262)the Fundamental Research Funds for the Central Universities,China(No.30922010706).
文摘The output feedback active disturbance rejection control of a valve-controlled cylinder electro-hydraulic servo system is investigated in this paper.First,a comprehensive nonlinear mathematical model that encompasses both matched and mismatched disturbances is formulated.Due to the fact that only position information can be measured,a linear Extended State Observer(ESO)is introduced to estimate unknown states and matched disturbances,while a dedicated disturbance observer is constructed to estimate mismatched disturbances.Different from the traditional observer results,the design of the disturbance observer used in this study is carried out under the constraint of output feedback.Furthermore,an output feedback nonlinear controller is proposed leveraging the aforementioned observers to achieve accurate trajectory tracking.To mitigate the inherent differential explosion problem of the traditional backstepping framework,a finite-time stable command filter is incorporated.Simultaneously,considering transient filtering errors,a set of error compensation signals are designed to counter their negative impact effectively.Theoretical analysis affirms that the proposed control strategy ensures the boundedness of all signals within the closed-loop system.Additionally,under the specific condition of only time-invariant disturbances in the system,the conclusion of asymptotic stability is established.Finally,the algorithm’s efficacy is validated through comparative experiments.
