With the occurrence of an adding driving field, the properties of the dispersion and the absorption of a four-level system are changed greatly. The system can produce the normal and anomalous dispersion regions with p...With the occurrence of an adding driving field, the properties of the dispersion and the absorption of a four-level system are changed greatly. The system can produce the normal and anomalous dispersion regions with proper parameters. Here, the driving fields can be seemed as knobs to manipulate the group velocity of a weak probe field between subluminal and superluminal.展开更多
A spherical robot based on a novel double ballast masses principle is developed for military reconnaissance and unknown environment exploration. The robot is driven by two DC motors, each of which drives one ballast m...A spherical robot based on a novel double ballast masses principle is developed for military reconnaissance and unknown environment exploration. The robot is driven by two DC motors, each of which drives one ballast mass, and the two ballast masses are placed symmetrically on the major axis. Compared with the traditional ballast mass principle, the robot has featured high speed, the ability of slope climbing and obstacle overcoming in linear motion. The robot has two inputs and three DOF, which is a nonholonomic and underactuated system. The dynamic model of the robot is constructed, and the linear motion performance of robot in theory is proved by Adams simulation. The control system is briefly introduced, and the performance of the prototype is tested by experiments at last.展开更多
The exploration of ecological safety in tourism sites can provide a concrete path for sustainable tourism development in a region.Based on the“Driver-Pressure-State-Impact-Response”(DPSIR)model,we constructed an ind...The exploration of ecological safety in tourism sites can provide a concrete path for sustainable tourism development in a region.Based on the“Driver-Pressure-State-Impact-Response”(DPSIR)model,we constructed an index system for the evaluation of tourism ecological security(TES)in the Silk Road Economic Belt(SREB)from 2005 to 2020.This index system was used to explore the characteristics of spatial and temporal dynamic evolution with the help of entropy weight TOPSIS method,dynamic index of TES and Markov probability transfer matrix,and a standard deviational ellipse(SDE)model and GM(1,1)model were constructed for spatial pattern analysis and prediction.The results indicate four key aspects of this system.(1)In terms of spatiotemporal evolution,the tourism ecological safety index(TESI)of the SREB increased,the TES levels of the northwestern and southwestern provinces and cities differed significantly,and the quality conditions of TES in the southwestern provinces and cities were better than in the northwest.(2)In terms of dynamic evolutionary characteristics,the speed of change at each level of the SREB was slow,but the level of TES has improved.The TES level has not shifted by leaps and bounds,and the shifts in the level type show“path dependence”and“self-locking”effects.(3)In terms of spatial and temporal distribution patterns,the spatial pattern of TES in the SREB is a“northwest-southeast”movement trend,and the spatial distribution appeared as“aggregation”from 2005 to 2020.The prediction results show that the center of gravity of TES in the SREB will shift to the southeast from 2025 to 2035,and the spatial spillover effect will be reduced.(4)In terms of driving factors,the number of star-rated hotels,and the amounts of industrial wastewater emissions,tourism foreign exchange earnings,forest coverage,and other parameters are the key factors affecting TES,and the booming tourism industry requires the interconnection and interpenetration of various factors.The results of this study can provide a reference for tourism development and ecological environmental protection in the Silk Road Economic Belt.展开更多
In order to solve the problem of metal impurities mixed in the production line of wood pulp nonwoven raw materials,intelligent metal detection and disposal automation equipment is designed.Based on the principle of el...In order to solve the problem of metal impurities mixed in the production line of wood pulp nonwoven raw materials,intelligent metal detection and disposal automation equipment is designed.Based on the principle of electromagnetic induction,the precise positioning of metal coordinates is realized by initial inspection and multi-directional re-inspection.Based on a geometry optimization driving algorithm,the cutting area is determined by locating the center of the circle that covers the maximum area.This approach aims to minimize the cutting area and maximize the use of materials.Additionally,the method strives to preserve as many fabrics at the edges as possible by employing the farthest edge covering circle algorithm.Based on a speed compensation algorithm,the flexible switching of upper and lower rolls is realized to ensure the maximum production efficiency.Compared with the metal detection device in the existing production line,the designed automation equipment has the advantages of higher detection sensitivity,more accurate metal coordinate positioning,smaller cutting material areas and higher production efficiency,which can make the production process more continuous,automated and intelligent.展开更多
Ecological land can provide people with ecological products and ecological services;and it plays an important role in maintaining the health and safety of the ecosystem.With China’s rapid urbanization development,eco...Ecological land can provide people with ecological products and ecological services;and it plays an important role in maintaining the health and safety of the ecosystem.With China’s rapid urbanization development,ecological land has been invaded in large quantities,and damaged seriously,even resulting in loses of its ecological function.Based on land use data from 1995 to 2015,our study explores the spatial and temporal evolution of the damage or recovery of ecological land in the Yangtze River Economic Belt(YREB).Two spatial models,geographic detector and geographic weighted regression(GWR),were employed to assess the global effects and the local effects of the driving factors for ecological land change,respectively.Our study divided the ecological land change into five types based on the degree of change as severe damage,slight damage,unchanged,slight recovery,and obvious recovery.The results show that from 1995 to 2015,the total area of ecological land in the YREB increased initially and then decreased,but the overall trend was decreasing.The total damaged area was larger than the recovered area.Arable land and woodland both showed downward trends.In terms of ecological land change over the past 20 years,the type of unchanged had the largest area,followed by slight damage and slight recovery.Our study further revealed that ecological land change was the net result of the interaction of many factors,and the explanatory power between any two driving factors was greater than that of any individual driving factor.In addition,driving factors have different impacts on ecological land change in different geographical locations.This knowledge should help land managers and policymakers to be better informed when developing pertinent land use policies at the regional and local levels.The lessons can also be extended to other regions for better management of their ecological land for sustainable use.展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos.61008063 and 10547108the Key Project of National Natural Science Foundation of China under Grant No.60837004+1 种基金Natural Science Foundation of Education Department of Guangdong Province of China under Grant No.LYM08099Natural Science Foundation of Foshan University
文摘With the occurrence of an adding driving field, the properties of the dispersion and the absorption of a four-level system are changed greatly. The system can produce the normal and anomalous dispersion regions with proper parameters. Here, the driving fields can be seemed as knobs to manipulate the group velocity of a weak probe field between subluminal and superluminal.
文摘A spherical robot based on a novel double ballast masses principle is developed for military reconnaissance and unknown environment exploration. The robot is driven by two DC motors, each of which drives one ballast mass, and the two ballast masses are placed symmetrically on the major axis. Compared with the traditional ballast mass principle, the robot has featured high speed, the ability of slope climbing and obstacle overcoming in linear motion. The robot has two inputs and three DOF, which is a nonholonomic and underactuated system. The dynamic model of the robot is constructed, and the linear motion performance of robot in theory is proved by Adams simulation. The control system is briefly introduced, and the performance of the prototype is tested by experiments at last.
基金The Scientific Research Fund Project of Yunnan Education Department(2021J0592)The Yunnan University of Finance and EconomicsProgramme(2022D13)The Graduate Student Innovation Fund Project of Yunnan University of Finance and Economics(2022YUFEYC10).
文摘The exploration of ecological safety in tourism sites can provide a concrete path for sustainable tourism development in a region.Based on the“Driver-Pressure-State-Impact-Response”(DPSIR)model,we constructed an index system for the evaluation of tourism ecological security(TES)in the Silk Road Economic Belt(SREB)from 2005 to 2020.This index system was used to explore the characteristics of spatial and temporal dynamic evolution with the help of entropy weight TOPSIS method,dynamic index of TES and Markov probability transfer matrix,and a standard deviational ellipse(SDE)model and GM(1,1)model were constructed for spatial pattern analysis and prediction.The results indicate four key aspects of this system.(1)In terms of spatiotemporal evolution,the tourism ecological safety index(TESI)of the SREB increased,the TES levels of the northwestern and southwestern provinces and cities differed significantly,and the quality conditions of TES in the southwestern provinces and cities were better than in the northwest.(2)In terms of dynamic evolutionary characteristics,the speed of change at each level of the SREB was slow,but the level of TES has improved.The TES level has not shifted by leaps and bounds,and the shifts in the level type show“path dependence”and“self-locking”effects.(3)In terms of spatial and temporal distribution patterns,the spatial pattern of TES in the SREB is a“northwest-southeast”movement trend,and the spatial distribution appeared as“aggregation”from 2005 to 2020.The prediction results show that the center of gravity of TES in the SREB will shift to the southeast from 2025 to 2035,and the spatial spillover effect will be reduced.(4)In terms of driving factors,the number of star-rated hotels,and the amounts of industrial wastewater emissions,tourism foreign exchange earnings,forest coverage,and other parameters are the key factors affecting TES,and the booming tourism industry requires the interconnection and interpenetration of various factors.The results of this study can provide a reference for tourism development and ecological environmental protection in the Silk Road Economic Belt.
基金National Key Research and Development Program of China(Nos.2022YFB4700600 and 2022YFB4700605)。
文摘In order to solve the problem of metal impurities mixed in the production line of wood pulp nonwoven raw materials,intelligent metal detection and disposal automation equipment is designed.Based on the principle of electromagnetic induction,the precise positioning of metal coordinates is realized by initial inspection and multi-directional re-inspection.Based on a geometry optimization driving algorithm,the cutting area is determined by locating the center of the circle that covers the maximum area.This approach aims to minimize the cutting area and maximize the use of materials.Additionally,the method strives to preserve as many fabrics at the edges as possible by employing the farthest edge covering circle algorithm.Based on a speed compensation algorithm,the flexible switching of upper and lower rolls is realized to ensure the maximum production efficiency.Compared with the metal detection device in the existing production line,the designed automation equipment has the advantages of higher detection sensitivity,more accurate metal coordinate positioning,smaller cutting material areas and higher production efficiency,which can make the production process more continuous,automated and intelligent.
基金The National Social Science Fund of China (19BGL283)The National Natural Science Foundation of China (41301619)
文摘Ecological land can provide people with ecological products and ecological services;and it plays an important role in maintaining the health and safety of the ecosystem.With China’s rapid urbanization development,ecological land has been invaded in large quantities,and damaged seriously,even resulting in loses of its ecological function.Based on land use data from 1995 to 2015,our study explores the spatial and temporal evolution of the damage or recovery of ecological land in the Yangtze River Economic Belt(YREB).Two spatial models,geographic detector and geographic weighted regression(GWR),were employed to assess the global effects and the local effects of the driving factors for ecological land change,respectively.Our study divided the ecological land change into five types based on the degree of change as severe damage,slight damage,unchanged,slight recovery,and obvious recovery.The results show that from 1995 to 2015,the total area of ecological land in the YREB increased initially and then decreased,but the overall trend was decreasing.The total damaged area was larger than the recovered area.Arable land and woodland both showed downward trends.In terms of ecological land change over the past 20 years,the type of unchanged had the largest area,followed by slight damage and slight recovery.Our study further revealed that ecological land change was the net result of the interaction of many factors,and the explanatory power between any two driving factors was greater than that of any individual driving factor.In addition,driving factors have different impacts on ecological land change in different geographical locations.This knowledge should help land managers and policymakers to be better informed when developing pertinent land use policies at the regional and local levels.The lessons can also be extended to other regions for better management of their ecological land for sustainable use.
