The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate...The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.展开更多
The Anthropocene era is characterized by the escalating impact of human activities on the environment,as well as the increasingly complex interactions among various components of the Earth system.These factors greatly...The Anthropocene era is characterized by the escalating impact of human activities on the environment,as well as the increasingly complex interactions among various components of the Earth system.These factors greatly affect the Earth's evolutionary trajectory.Despite notable strides in sustainable development practices worldwide,it remains unclear to what extent we have achieved Earth sustainability.Consequently,there is a pressing need to enhance conceptual and methodological frameworks to measure sustainability progress accurately.To address this need,we developed an Earth Vitality Framework that aids in tracking the Earth sustainability progress by considering interactions between spheres,recognizing the equal relationship between humans and nature,and presenting a threshold scheme for all measures.We applied this framework at global and national scales to demonstrate its usefulness.Our findings reveal that the current Earth Vitality Index is 63.74,indicating that the Earth is in a"weak"vitality.Irrational social institutions,unsatisfactory life experiences and the poor state of the biosphere and hydrosphere have remarkably affected the Earth vitality.Additionally,inequality exists between high-income and low-income countries.Although most of the former exhibit poor human-nature interaction,all of them enjoy good human well-being,while the opposite is true for the latter.Finally,we summarize the challenges and possible options for enhancing the Earth vitality in terms of coping with spillover effects,tipping cascades,feedback,and heterogeneity.展开更多
Based on the daily temperature, precipitation and sunshine data of the National Weather Station of Weixian County, Hebei, China from 1961 to 2014, the average temperature, accumulated temperature, precipitation and su...Based on the daily temperature, precipitation and sunshine data of the National Weather Station of Weixian County, Hebei, China from 1961 to 2014, the average temperature, accumulated temperature, precipitation and sunshine trends of the year and four seasons were analyzed. The results showed an upward trend of the average annual temperature, average annual maximum temperature and average annual minimum temperature and the minimum temperature increase is the largest. The average temperature in summer is decreasing, while the average temperature, maximum temperature and minimum temperature in spring, autumn and winter showed an upward trend. ≥0°C accumulated temperature increased by 193.82°C for 54 years, and ≥10°C accumulated temperature increased 54.59°C for 54 years. Weixian County sunshine hours were 119.121 h/10 years to reduce the rate of adverse effects on crop growth;annual precipitation decreased by 116.4 mm for 54 years, the maximum precipitation decreased by 8.2 mm, and the number of annual precipitation decreased 18.6 d, which caused great pressure on groundwater recharge展开更多
Posture adjustment of open-type hard rock tunnel boring machine(TBM) can be achieved by properly adjusting the hydraulic pressure of gripper cylinder and torque cylinders. However, the time-varying inhomogeneous load ...Posture adjustment of open-type hard rock tunnel boring machine(TBM) can be achieved by properly adjusting the hydraulic pressure of gripper cylinder and torque cylinders. However, the time-varying inhomogeneous load acting on tunneling face of TBM and complex stratum working condition can cause the trajectory deviation. In this paper,the position and posture rectification kinematics and dynamics models of TBM have been established in order to track the trajectory. Moreover, there are uncertain parameters and uncertain loads from complex working conditions in the dynamic model. An indirect adaptive robust control strategy is applied to achieve precise position and posture trajectory tracking control. Simulation results show when the position deviation only occurs in Y-axis and the current orientation is parallel with the designed axis, the deviation can be corrected by controlling the pressure of gripper cylinder and the actual trajectory meets the designed axis when TBM is pushed forward 0.14 m in X-axis. If the deviation only occurs in Z-axis, then the deviation can be corrected by controlling torque cylinders. If the position deviation occurs both in Y-axis and Z-axis at the same time, the pressure of gripper cylinder and torque cylinders should be controlled at the same time to rectify the deviation. Simulation results are shown to illustrate the e ectiveness and robustness of the proposed controller. This research proposes an indirect adaptive robust controller that can track the planned tracking trajectory smoothly and rapidly.展开更多
Clustering is an unsupervised learning technology,and it groups information(observations or datasets)according to similarity measures.Developing clustering algorithms is a hot topic in recent years,and this area devel...Clustering is an unsupervised learning technology,and it groups information(observations or datasets)according to similarity measures.Developing clustering algorithms is a hot topic in recent years,and this area develops rapidly with the increasing complexity of data and the volume of datasets.In this paper,the concept of clustering is introduced,and the clustering technologies are analyzed from traditional and modern perspectives.First,this paper summarizes the principles,advantages,and disadvantages of 20 traditional clustering algorithms and 4 modern algorithms.Then,the core elements of clustering are presented,such as similarity measures and evaluation index.Considering that data processing is often applied in vehicle engineering,finally,some specific applications of clustering algorithms in vehicles are listed and the future development of clustering in the era of big data is highlighted.The purpose of this review is to make a comprehensive survey that helps readers learn various clustering algorithms and choose the appropriate methods to use,especially in vehicles.展开更多
Introduction:Bacillus cereus(B.cereus)is a common gram-positive bacterium that contaminates starch-rich food and can cause outbreaks of foodborne diseases.This study describes characteristics of outbreaks caused by B....Introduction:Bacillus cereus(B.cereus)is a common gram-positive bacterium that contaminates starch-rich food and can cause outbreaks of foodborne diseases.This study describes characteristics of outbreaks caused by B.cereus in China during 2010–2020 and explore the possible reasons for changes in the number of outbreaks over time.Results of this analysis can efficiently help guide and allocate public resources to prevent B.cereus caused foodborne diseases.Methods:Descriptive statistical methods were used to analysis the data on B.cereus outbreaks in China during this period.The data were identified,reported at all levels in China through National Foodborne Disease Outbreak Surveillance System.Results:From 2010 to 2020,a total of 419 foodborne outbreaks prompted by B.cereus were reported in China,leading to 7,892 cases,2,786 hospital admissions,and 5 fatalities.The bulk of the outbreaks were recorded in the summer,primarily between May and September.The most recurrent food vehicle was linked with rice or flour-based products,notably those made with rice or fried rice.School canteens bore the brunt of the B.cereus outbreaks.In multifactor outbreaks,food contamination was identified as the most common culprit;while in instances where only one factor contributed,improper storage was most frequently implicated.Conclusion:The prevalence of B.cereus outbreaks remained relatively consistent throughout the studied period.Understanding the types of foods,causative factors,and contributing elements leading to B.cereus outbreaks can help inform prevention strategies for foodborne illnesses.The majority of outbreaks were associated with rice-or flour-based foods in school canteens,suggesting contamination and improper storage during food preparation.Consequently,it is essential to prioritize continuous education for canteen staff on food safety,efficacious management,and proper practices.The implementation of comprehensive guidelines,encompassing multiple critical aspects,can potentially reduce the occurrence of B.cereus outbreaks.展开更多
ABSTRACT Introduction:Mushroom poisoning was the leading cause of foodborne disease outbreaks and outbreak-associated deaths in China.Mushroom poisoning outbreak surveillance can provide insight into the epidemiologic...ABSTRACT Introduction:Mushroom poisoning was the leading cause of foodborne disease outbreaks and outbreak-associated deaths in China.Mushroom poisoning outbreak surveillance can provide insight into the epidemiological characteristics of mushroom poisonings and guide policymaking and health education to reduce illnesses and deaths.Methods:Foodborne Disease Outbreak Surveillance System was upgraded in 2011 to collect foodborne disease outbreaks in China.Mushroom poisoning outbreaks during 2010–2020 were selected to analyze geographical distribution,seasonal distribution,and setting of food preparation.Results:A total of 10,036 outbreaks,which resulted in 38,676 illnesses and 788 deaths,were reported in this period.Mushroom poisonings occurred all over the country,but with highest incidence in the southwest and central China.展开更多
In this paper,the event-triggered consensus control problem for nonlinear uncertain multi-agent systems subject to unknown parameters and external disturbances is considered.The dynamics of subsystems are second-order...In this paper,the event-triggered consensus control problem for nonlinear uncertain multi-agent systems subject to unknown parameters and external disturbances is considered.The dynamics of subsystems are second-order with similar structures,and the nodes are connected by undirected graphs.The event-triggered mechanisms are not only utilized in the transmission of information from the controllers to the actuators,and from the sensors to the controllers within each agent,but also in the communication between agents.Based on the adaptive backstepping method,extra estimators are introduced to handle the unknown parameters,and the measurement errors that occur during the event-triggered communication are well handled by designing compensating terms for the control signals.The presented distributed event-triggered adaptive control laws can guarantee the boundness of the consensus tracking errors and the Zeno behavior is avoided.Meanwhile,the update frequency of the controllers and the load of communication burden are vastly reduced.The obtained control protocol is further applied to a multi-input multi-output second-order nonlinear multi-agent system,and the simulation results show the effectiveness and advantages of our proposed method.展开更多
Aspects of time budgets, activity patterns and rut-related changes in behavior are well documented in temperate un-gulates; however, the application of this understanding to tropical and sub-tropical ungulate species ...Aspects of time budgets, activity patterns and rut-related changes in behavior are well documented in temperate un-gulates; however, the application of this understanding to tropical and sub-tropical ungulate species has attracted less attention and remains an area that may re-shape our knowledge of ungulate behavior. Eld's deer Cervus eldi hainanus has a tropical and sub-tropical distribution on Hainan Island, China, and males have an extended rut exceeding five months during which they do not maintain harems or defend resources. We studied males from the only remaining population on Hainan Island, and describe rut-related changes in behavior by collecting data on time budgets and activity patterns. We show that male Eld's deer do not fol- low a strict crepuscular activity pattern, do not spend the majority of their time foraging and do not increase foraging nor display rut-induced hypophagia during rut, in obvious contrast to temperate ungulates. These results are discussed in light of current hy- potheses explaining the proximate mechanisms governing feeding time in ungulates, while appreciating the need for further re-search .展开更多
The electric unmanned aerial vehicles (UAVs) are rapidly growing due to their abilities to perform some difficult or dangerous tasks as well as many public services including real-time monitoring, wireless coverage, s...The electric unmanned aerial vehicles (UAVs) are rapidly growing due to their abilities to perform some difficult or dangerous tasks as well as many public services including real-time monitoring, wireless coverage, search and rescue, wildlife surveys, and precision agriculture. However, the electrochemical power supply system of UAV is a critical issue in terms of its energy/power densities and lifetime for service endurance. In this paper, the current power supply systems used in UAVs are comprehensively reviewed and analyzed on the existing power configurations and the energy management systems. It is identified that a single type of electrochemical power source is not enough to support a UAV to achieve a long-haul flight;hence, a hybrid power system architecture is necessary. To make use of the advantages of each type of power source to increase the endurance and achieve good performance of the UAVs, the hybrid systems containing two or three types of power sources (fuel cell,battery, solar cell, and supercapacitor,) have to be developed. In this regard, the selection of an appropriate hybrid power structure with the optimized energy management system is critical for the efficient operation of a UAV. It is found that the data-driven models with artificial intelligence (AI) are promising in intelligent energy management. This paper can provide insights and guidelines for future research and development into the design and fabrication of the advanced UAV power systems.展开更多
基金the support of the instrument and equipment fund of the Key Laboratory of Special Energy,Ministry of Education,Nanjing University of Science and Technology,China.
文摘The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.
基金supported by Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.42121001)Major Program of National Natural Science Foundation of China(Grant No.41590840).
文摘The Anthropocene era is characterized by the escalating impact of human activities on the environment,as well as the increasingly complex interactions among various components of the Earth system.These factors greatly affect the Earth's evolutionary trajectory.Despite notable strides in sustainable development practices worldwide,it remains unclear to what extent we have achieved Earth sustainability.Consequently,there is a pressing need to enhance conceptual and methodological frameworks to measure sustainability progress accurately.To address this need,we developed an Earth Vitality Framework that aids in tracking the Earth sustainability progress by considering interactions between spheres,recognizing the equal relationship between humans and nature,and presenting a threshold scheme for all measures.We applied this framework at global and national scales to demonstrate its usefulness.Our findings reveal that the current Earth Vitality Index is 63.74,indicating that the Earth is in a"weak"vitality.Irrational social institutions,unsatisfactory life experiences and the poor state of the biosphere and hydrosphere have remarkably affected the Earth vitality.Additionally,inequality exists between high-income and low-income countries.Although most of the former exhibit poor human-nature interaction,all of them enjoy good human well-being,while the opposite is true for the latter.Finally,we summarize the challenges and possible options for enhancing the Earth vitality in terms of coping with spillover effects,tipping cascades,feedback,and heterogeneity.
文摘Based on the daily temperature, precipitation and sunshine data of the National Weather Station of Weixian County, Hebei, China from 1961 to 2014, the average temperature, accumulated temperature, precipitation and sunshine trends of the year and four seasons were analyzed. The results showed an upward trend of the average annual temperature, average annual maximum temperature and average annual minimum temperature and the minimum temperature increase is the largest. The average temperature in summer is decreasing, while the average temperature, maximum temperature and minimum temperature in spring, autumn and winter showed an upward trend. ≥0°C accumulated temperature increased by 193.82°C for 54 years, and ≥10°C accumulated temperature increased 54.59°C for 54 years. Weixian County sunshine hours were 119.121 h/10 years to reduce the rate of adverse effects on crop growth;annual precipitation decreased by 116.4 mm for 54 years, the maximum precipitation decreased by 8.2 mm, and the number of annual precipitation decreased 18.6 d, which caused great pressure on groundwater recharge
基金Supported by National Basic Research Program of China(973 Program,Grant No.2013CB035406)Science Fund for Creative Research Groups of National Natural Science Foundation of China(Grant No.61621002)National Natural Science Foundation of China(Grant No.61633019)
文摘Posture adjustment of open-type hard rock tunnel boring machine(TBM) can be achieved by properly adjusting the hydraulic pressure of gripper cylinder and torque cylinders. However, the time-varying inhomogeneous load acting on tunneling face of TBM and complex stratum working condition can cause the trajectory deviation. In this paper,the position and posture rectification kinematics and dynamics models of TBM have been established in order to track the trajectory. Moreover, there are uncertain parameters and uncertain loads from complex working conditions in the dynamic model. An indirect adaptive robust control strategy is applied to achieve precise position and posture trajectory tracking control. Simulation results show when the position deviation only occurs in Y-axis and the current orientation is parallel with the designed axis, the deviation can be corrected by controlling the pressure of gripper cylinder and the actual trajectory meets the designed axis when TBM is pushed forward 0.14 m in X-axis. If the deviation only occurs in Z-axis, then the deviation can be corrected by controlling torque cylinders. If the position deviation occurs both in Y-axis and Z-axis at the same time, the pressure of gripper cylinder and torque cylinders should be controlled at the same time to rectify the deviation. Simulation results are shown to illustrate the e ectiveness and robustness of the proposed controller. This research proposes an indirect adaptive robust controller that can track the planned tracking trajectory smoothly and rapidly.
基金supported in part by the founding of the State Key Laboratory of Industrial Control Technology,Zhejiang University(ICT2021B19)the Technological Innovation and Application Demonstration in Chongqing(Major Themes of Industry:cstc2019jscx-zdztzxX0033,cstc2019jscx-fxyd0158).
文摘Clustering is an unsupervised learning technology,and it groups information(observations or datasets)according to similarity measures.Developing clustering algorithms is a hot topic in recent years,and this area develops rapidly with the increasing complexity of data and the volume of datasets.In this paper,the concept of clustering is introduced,and the clustering technologies are analyzed from traditional and modern perspectives.First,this paper summarizes the principles,advantages,and disadvantages of 20 traditional clustering algorithms and 4 modern algorithms.Then,the core elements of clustering are presented,such as similarity measures and evaluation index.Considering that data processing is often applied in vehicle engineering,finally,some specific applications of clustering algorithms in vehicles are listed and the future development of clustering in the era of big data is highlighted.The purpose of this review is to make a comprehensive survey that helps readers learn various clustering algorithms and choose the appropriate methods to use,especially in vehicles.
基金The National Key Research and Development Program of China(2022YFC2602303,2021YFF0703804,2017YFC1600100)the Research Project on Health Policy of Shanghai(2021HP10).
文摘Introduction:Bacillus cereus(B.cereus)is a common gram-positive bacterium that contaminates starch-rich food and can cause outbreaks of foodborne diseases.This study describes characteristics of outbreaks caused by B.cereus in China during 2010–2020 and explore the possible reasons for changes in the number of outbreaks over time.Results of this analysis can efficiently help guide and allocate public resources to prevent B.cereus caused foodborne diseases.Methods:Descriptive statistical methods were used to analysis the data on B.cereus outbreaks in China during this period.The data were identified,reported at all levels in China through National Foodborne Disease Outbreak Surveillance System.Results:From 2010 to 2020,a total of 419 foodborne outbreaks prompted by B.cereus were reported in China,leading to 7,892 cases,2,786 hospital admissions,and 5 fatalities.The bulk of the outbreaks were recorded in the summer,primarily between May and September.The most recurrent food vehicle was linked with rice or flour-based products,notably those made with rice or fried rice.School canteens bore the brunt of the B.cereus outbreaks.In multifactor outbreaks,food contamination was identified as the most common culprit;while in instances where only one factor contributed,improper storage was most frequently implicated.Conclusion:The prevalence of B.cereus outbreaks remained relatively consistent throughout the studied period.Understanding the types of foods,causative factors,and contributing elements leading to B.cereus outbreaks can help inform prevention strategies for foodborne illnesses.The majority of outbreaks were associated with rice-or flour-based foods in school canteens,suggesting contamination and improper storage during food preparation.Consequently,it is essential to prioritize continuous education for canteen staff on food safety,efficacious management,and proper practices.The implementation of comprehensive guidelines,encompassing multiple critical aspects,can potentially reduce the occurrence of B.cereus outbreaks.
基金The National Key Research and Development Program of China(Grant number 2017YFC1601503).
文摘ABSTRACT Introduction:Mushroom poisoning was the leading cause of foodborne disease outbreaks and outbreak-associated deaths in China.Mushroom poisoning outbreak surveillance can provide insight into the epidemiological characteristics of mushroom poisonings and guide policymaking and health education to reduce illnesses and deaths.Methods:Foodborne Disease Outbreak Surveillance System was upgraded in 2011 to collect foodborne disease outbreaks in China.Mushroom poisoning outbreaks during 2010–2020 were selected to analyze geographical distribution,seasonal distribution,and setting of food preparation.Results:A total of 10,036 outbreaks,which resulted in 38,676 illnesses and 788 deaths,were reported in this period.Mushroom poisonings occurred all over the country,but with highest incidence in the southwest and central China.
基金supported by National Key R&D Program of China(No.2018YFA0703800)Science Fund for Creative Research Group of the National Natural Science Foundation of China(No.61621002)。
文摘In this paper,the event-triggered consensus control problem for nonlinear uncertain multi-agent systems subject to unknown parameters and external disturbances is considered.The dynamics of subsystems are second-order with similar structures,and the nodes are connected by undirected graphs.The event-triggered mechanisms are not only utilized in the transmission of information from the controllers to the actuators,and from the sensors to the controllers within each agent,but also in the communication between agents.Based on the adaptive backstepping method,extra estimators are introduced to handle the unknown parameters,and the measurement errors that occur during the event-triggered communication are well handled by designing compensating terms for the control signals.The presented distributed event-triggered adaptive control laws can guarantee the boundness of the consensus tracking errors and the Zeno behavior is avoided.Meanwhile,the update frequency of the controllers and the load of communication burden are vastly reduced.The obtained control protocol is further applied to a multi-input multi-output second-order nonlinear multi-agent system,and the simulation results show the effectiveness and advantages of our proposed method.
基金Funding for this study was provided by National Nature Science Foundation of China (30430120). We followed guidelines for the use of animals in research as pub-lished by the journal Animal Behaviour. We thank staff at Hainan Datian National Nature Reserve for assistance during our field research with special thanks to Li Shanyuan and Xing Yichang who graciously contributed their time and effort during this study.
文摘Aspects of time budgets, activity patterns and rut-related changes in behavior are well documented in temperate un-gulates; however, the application of this understanding to tropical and sub-tropical ungulate species has attracted less attention and remains an area that may re-shape our knowledge of ungulate behavior. Eld's deer Cervus eldi hainanus has a tropical and sub-tropical distribution on Hainan Island, China, and males have an extended rut exceeding five months during which they do not maintain harems or defend resources. We studied males from the only remaining population on Hainan Island, and describe rut-related changes in behavior by collecting data on time budgets and activity patterns. We show that male Eld's deer do not fol- low a strict crepuscular activity pattern, do not spend the majority of their time foraging and do not increase foraging nor display rut-induced hypophagia during rut, in obvious contrast to temperate ungulates. These results are discussed in light of current hy- potheses explaining the proximate mechanisms governing feeding time in ungulates, while appreciating the need for further re-search .
基金supported in part by the founding of state key laboratory of industrial control technology,Zhejiang University(ICT2021B19)the Technological Innovation and Application Demonstration in Chongqing(Major Themes of Industry:cstc2019jscx-zdztzxX0033,cstc2019jscxfxyd0158)the National Natural Science Foundation of China(NO.22005026,21908142).
文摘The electric unmanned aerial vehicles (UAVs) are rapidly growing due to their abilities to perform some difficult or dangerous tasks as well as many public services including real-time monitoring, wireless coverage, search and rescue, wildlife surveys, and precision agriculture. However, the electrochemical power supply system of UAV is a critical issue in terms of its energy/power densities and lifetime for service endurance. In this paper, the current power supply systems used in UAVs are comprehensively reviewed and analyzed on the existing power configurations and the energy management systems. It is identified that a single type of electrochemical power source is not enough to support a UAV to achieve a long-haul flight;hence, a hybrid power system architecture is necessary. To make use of the advantages of each type of power source to increase the endurance and achieve good performance of the UAVs, the hybrid systems containing two or three types of power sources (fuel cell,battery, solar cell, and supercapacitor,) have to be developed. In this regard, the selection of an appropriate hybrid power structure with the optimized energy management system is critical for the efficient operation of a UAV. It is found that the data-driven models with artificial intelligence (AI) are promising in intelligent energy management. This paper can provide insights and guidelines for future research and development into the design and fabrication of the advanced UAV power systems.