Autonomous navigation is a key technology for unmanned motion platforms to perform their tasks smoothly.The current approaches for daytime polarization navigation have been extensively researched.However,the polarizat...Autonomous navigation is a key technology for unmanned motion platforms to perform their tasks smoothly.The current approaches for daytime polarization navigation have been extensively researched.However,the polarization light intensity is the fundamental information within the polarization image,and the light intensity at night is 6-8 orders of magnitude lower than that during the day,which increase the noise and the loss of local polarization information due to occlusion,resulting in a significant decrease in the polarization orientation accuracy.Aimed at the problem,a bio-inspired model is introduced to denoise and enhance weak nighttime polarization patterns.Further,to address the issue of outlier interference in the occluded environment during practical application,a fast-fitting method of the solar meridian based on the anti-symmetric distribution of the polarization angle adjusted by Proportional and Differential(PD)control is proposed.The experimental results show that the method proposed in this paper achieves a dynamic orientation error Root Mean Square Error(RMSE)of 0.7°in the weak polarization mode at night and in the presence of local occlusion.The proposed method has strong robustness under weak polarization occlusion at night,and the orientation accuracy is improved by 97%and 80%in comparison to the least squares method,which provides a new method for polarization navigation at night.This effectively improves the robustness and environmental applicability of the bionic polarization compass for nighttime applications.展开更多
Nighttime navigation faces challenges from limited data and interference,especially when satellite signals are unavailable.Leveraging lunar polarized light,polarization navigation offers a promising solution for night...Nighttime navigation faces challenges from limited data and interference,especially when satellite signals are unavailable.Leveraging lunar polarized light,polarization navigation offers a promising solution for nighttime autonomous navigation.Current algorithms,however,are limited by the requirement for known horizontal attitudes,restricting applications.This study introduces an autonomous 3-D attitude determination method to overcome this limitation.Our approach utilizes the Angle of Polarization(AOP)at night to extract neutral points from the AOP pattern.This allows for the calculation of polarization meridian plane information for attitude determination.Subsequently,we present an optimized Polarization TRIAD(Pol-TRIAD)algorithm to acquire the 3-D attitude.The proposed method outperforms the existing approaches in outdoor experiments by achieving lower Root Mean Square Error(RMSE).For one baseline attitude,it improves pitch by 31.7%,roll by 21.7%,and yaw by 2.6%,while for the attitude with a larger tilt angle,the improvements are 64.4%,30.4%,and 9.1%,respectively.展开更多
Underwater navigation system is an indispensable part for autonomous underwater vehicles.Due to the indiscernibility of satellite signal,however,the underwater navigation problem is quite challenging,and a satellite-f...Underwater navigation system is an indispensable part for autonomous underwater vehicles.Due to the indiscernibility of satellite signal,however,the underwater navigation problem is quite challenging,and a satellite-free navigation scheme should be looked for.Polarization navigation,inspired by insects’capability of autonomous homing and foraging,is an alternative solution to satellite navigation with great application potential.Underwater polarization provides an indirect sun compass to animals for orientation determination.However,it is difficult to apply terrestrial solar-tracking methodologies in underwater situations due to the refraction of polarized skylight at the air–water interface.To resolve this issue,an underwater solar-tracking algorithm is developed based on the underwater refraction-polarization pattern inside the Snell’s window.By employing Snell’s law and Fresnel refraction formula to decouple the refractive ray bending and polarization deflection,the celestial polarization pattern is obtained based on underwater measurement.To further improve the accuracy,the degree of polarization is employed as a weight factor for E-vector.A long-lasting underwater experiment was conducted to validate the effectiveness of the proposed approach,and the results showed the root-mean-square errors of solar zenith and azimuth employing this algorithm were 0.3°and 1.3°,respectively.Our experimental results show that the refraction-polarization pattern inside the Snell’s window exhibits immense potential to improve the solar-tracking accuracy for underwater navigation.展开更多
Dear Editor,This letter presents an organoid segmentation model based on multi-axis attention with convolution parallel block.MACPNet adeptly captures dynamic dependencies within bright-field microscopy images,improvi...Dear Editor,This letter presents an organoid segmentation model based on multi-axis attention with convolution parallel block.MACPNet adeptly captures dynamic dependencies within bright-field microscopy images,improving global modeling beyond conventional UNet.展开更多
The Covid-19 pandemic produced a complex combination of intense negative emotions among the general public,influencing people's coping reactions toward the pandemic.Yet each discrete emotion may affect people'...The Covid-19 pandemic produced a complex combination of intense negative emotions among the general public,influencing people's coping reactions toward the pandemic.Yet each discrete emotion may affect people's behaviors in different ways.Unveiling the specific emotion–behavior relationships can provide valuable implications for designing effective intervention programs.Through the lens of the appraisal theory of emotion,we assessed the relationships between negative emotions and pandemic-related behaviors among the Chinese population midst the early outbreak of the pandemic.An anonymous online survey was distributed to mainland of China participants(n=2976),which assessed individuals'emotional states and behavioral reactions to the pandemic.Consistent with the differential appraisal theme underlying each negative emotion as delineated by the appraisal theory,mixed relationships between emotions and pandemic-related behaviors were revealed.Specifically,anxiety was positively associated with behaviors of seeking pandemic-related information,sharing such information,and stockpiling preventive goods,yet,contrary to prediction,anxious people were reluctant to adopt preventive measures,which is maladaptive.Sad people sought information less frequently and exhibited lower intention to stockpile preventive goods;but,opposing prediction,they shared information less frequently.Angry people were more active in sharing information and in stockpiling preventive goods.These findings suggest that public health practitioners can utilize the emotion–behavior relationships to identify the vulnerable individuals who tend to adopt maladaptive coping behaviors,help them address emotional distress,and encourage their adoption of effective coping behaviors.展开更多
The emergence of systems-of-systems (SoS) brings new challenges for reliability research within the field of system-of-systems engineering (SoSE). In response, this study examines the requirements for measurement, eva...The emergence of systems-of-systems (SoS) brings new challenges for reliability research within the field of system-of-systems engineering (SoSE). In response, this study examines the requirements for measurement, evaluation, and design/testing of SoS reliability. Drawing on research practice in aerospace engineering, it outlines the concept of equipment SoS and proposes a corresponding research framework for equipment SoS reliability. By analyzing both the reliability demands of SoSE and the current research practice in aerospace equipment SoS, this study identifies several key challenges: Modeling of SoS and its reliability, network reliability in SoS, propagation and recovery of disturbances in SoS, reliability design and simulation methods, and reliability management in SoSE.展开更多
基金co-supported by the Excellent Youth Foundation of Shanxi Province,China(No.202103021222011)the Key Research and Development project of Shanxi Province of China(No.202202020101002)+3 种基金the Fundamental Research Program of Shanxi Province of China(No.202303021211150)the Aviation Science Foundation of China(No.2022Z0220U0002)the Graduate Education Innovation Plan Project of Shanxi Province,China(No.2023KY588)the Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement,China(No.201905D121001).
文摘Autonomous navigation is a key technology for unmanned motion platforms to perform their tasks smoothly.The current approaches for daytime polarization navigation have been extensively researched.However,the polarization light intensity is the fundamental information within the polarization image,and the light intensity at night is 6-8 orders of magnitude lower than that during the day,which increase the noise and the loss of local polarization information due to occlusion,resulting in a significant decrease in the polarization orientation accuracy.Aimed at the problem,a bio-inspired model is introduced to denoise and enhance weak nighttime polarization patterns.Further,to address the issue of outlier interference in the occluded environment during practical application,a fast-fitting method of the solar meridian based on the anti-symmetric distribution of the polarization angle adjusted by Proportional and Differential(PD)control is proposed.The experimental results show that the method proposed in this paper achieves a dynamic orientation error Root Mean Square Error(RMSE)of 0.7°in the weak polarization mode at night and in the presence of local occlusion.The proposed method has strong robustness under weak polarization occlusion at night,and the orientation accuracy is improved by 97%and 80%in comparison to the least squares method,which provides a new method for polarization navigation at night.This effectively improves the robustness and environmental applicability of the bionic polarization compass for nighttime applications.
基金supported in part by the National Key Research and Development Program of China(Nos.2020YFA0711200,2022YFB4701301)in part by the Defense Industrial Technology Development Program,China(No.JCKY2021601B016)+1 种基金in part by the Fundamental Research Funds for the Central Universities,China(No.YWF-23-JC-07)in part by the National Natural Science Foundation of China(No.62425302)。
文摘Nighttime navigation faces challenges from limited data and interference,especially when satellite signals are unavailable.Leveraging lunar polarized light,polarization navigation offers a promising solution for nighttime autonomous navigation.Current algorithms,however,are limited by the requirement for known horizontal attitudes,restricting applications.This study introduces an autonomous 3-D attitude determination method to overcome this limitation.Our approach utilizes the Angle of Polarization(AOP)at night to extract neutral points from the AOP pattern.This allows for the calculation of polarization meridian plane information for attitude determination.Subsequently,we present an optimized Polarization TRIAD(Pol-TRIAD)algorithm to acquire the 3-D attitude.The proposed method outperforms the existing approaches in outdoor experiments by achieving lower Root Mean Square Error(RMSE).For one baseline attitude,it improves pitch by 31.7%,roll by 21.7%,and yaw by 2.6%,while for the attitude with a larger tilt angle,the improvements are 64.4%,30.4%,and 9.1%,respectively.
基金supported by grants from the National Natural Science Foundation of China(Nos.61751302,62003017,61627810,61833013,61973012)Science and Technology Key Innovative Project of Hangzhou,China(No.20182014B06)。
文摘Underwater navigation system is an indispensable part for autonomous underwater vehicles.Due to the indiscernibility of satellite signal,however,the underwater navigation problem is quite challenging,and a satellite-free navigation scheme should be looked for.Polarization navigation,inspired by insects’capability of autonomous homing and foraging,is an alternative solution to satellite navigation with great application potential.Underwater polarization provides an indirect sun compass to animals for orientation determination.However,it is difficult to apply terrestrial solar-tracking methodologies in underwater situations due to the refraction of polarized skylight at the air–water interface.To resolve this issue,an underwater solar-tracking algorithm is developed based on the underwater refraction-polarization pattern inside the Snell’s window.By employing Snell’s law and Fresnel refraction formula to decouple the refractive ray bending and polarization deflection,the celestial polarization pattern is obtained based on underwater measurement.To further improve the accuracy,the degree of polarization is employed as a weight factor for E-vector.A long-lasting underwater experiment was conducted to validate the effectiveness of the proposed approach,and the results showed the root-mean-square errors of solar zenith and azimuth employing this algorithm were 0.3°and 1.3°,respectively.Our experimental results show that the refraction-polarization pattern inside the Snell’s window exhibits immense potential to improve the solar-tracking accuracy for underwater navigation.
基金supported by the Xinjiang Tianchi Talents Program(E33B9401)the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2023D01E15)+1 种基金the National Natural Science Foundation of China(62302495)the National Natural Science Foundation of China(62373348)。
文摘Dear Editor,This letter presents an organoid segmentation model based on multi-axis attention with convolution parallel block.MACPNet adeptly captures dynamic dependencies within bright-field microscopy images,improving global modeling beyond conventional UNet.
基金supported by grants from the National Natural Science Foundation of China(No.71802198)University of South China Covid-19 epidemic prevention and control scientific research emergency project(2020-2-5),Hunan province 2020 innovative province construction special topic to combat Covid-19 epidemic emergency(2020SK3010)Major Program of the National Social Science Foundation of China(No.21ZDA036).
文摘The Covid-19 pandemic produced a complex combination of intense negative emotions among the general public,influencing people's coping reactions toward the pandemic.Yet each discrete emotion may affect people's behaviors in different ways.Unveiling the specific emotion–behavior relationships can provide valuable implications for designing effective intervention programs.Through the lens of the appraisal theory of emotion,we assessed the relationships between negative emotions and pandemic-related behaviors among the Chinese population midst the early outbreak of the pandemic.An anonymous online survey was distributed to mainland of China participants(n=2976),which assessed individuals'emotional states and behavioral reactions to the pandemic.Consistent with the differential appraisal theme underlying each negative emotion as delineated by the appraisal theory,mixed relationships between emotions and pandemic-related behaviors were revealed.Specifically,anxiety was positively associated with behaviors of seeking pandemic-related information,sharing such information,and stockpiling preventive goods,yet,contrary to prediction,anxious people were reluctant to adopt preventive measures,which is maladaptive.Sad people sought information less frequently and exhibited lower intention to stockpile preventive goods;but,opposing prediction,they shared information less frequently.Angry people were more active in sharing information and in stockpiling preventive goods.These findings suggest that public health practitioners can utilize the emotion–behavior relationships to identify the vulnerable individuals who tend to adopt maladaptive coping behaviors,help them address emotional distress,and encourage their adoption of effective coping behaviors.
基金supported by the National Natural Science Foundation of China(Grant No.72071011).
文摘The emergence of systems-of-systems (SoS) brings new challenges for reliability research within the field of system-of-systems engineering (SoSE). In response, this study examines the requirements for measurement, evaluation, and design/testing of SoS reliability. Drawing on research practice in aerospace engineering, it outlines the concept of equipment SoS and proposes a corresponding research framework for equipment SoS reliability. By analyzing both the reliability demands of SoSE and the current research practice in aerospace equipment SoS, this study identifies several key challenges: Modeling of SoS and its reliability, network reliability in SoS, propagation and recovery of disturbances in SoS, reliability design and simulation methods, and reliability management in SoSE.
