Today＇s production systems are demanded to exhibit an increased flexibility and mutability in order to deal with dynamically changing conditions, objectives and an increasing number of product variants within industr...Today＇s production systems are demanded to exhibit an increased flexibility and mutability in order to deal with dynamically changing conditions, objectives and an increasing number of product variants within industrial turbulent environments. Flexible automated systems are requested in order to improve dynamic production efficiency, e.g. robot-based hardware and PC-based controllers, but these usually induce a significantly higher production complexity, whereby the efforts for planning and programming, but also setups and reconfiguration, expand. In this paper a definition and some concepts of self-optimizing assembly systems are presented to describe possible ways to reduce the planning efforts in complex production systems. The concept of self-optimization in assembly systems will be derived from a theoretical approach and will be transferred to a specific application scenario---the automated assembly of a miniaturized solid state laser--where the challenges of unpredictable influences from e.g. component tolerances can be overcome by the help of self-optimization.展开更多
Our analysis of the surface aerosol and ultraviolet （UV） measurements in Pearl River Delta （PRD） region shows that the surface UV radiation is reduced by more than 50% due to high aerosol concentrations. This has ...Our analysis of the surface aerosol and ultraviolet （UV） measurements in Pearl River Delta （PRD） region shows that the surface UV radiation is reduced by more than 50% due to high aerosol concentrations. This has important impacts on urban ecosystem and photochemistry, especially on ozone photochemical production over the region. The quantitative effect of aerosols on surface ozone is evaluated by analyzing surface observations （including ozone, ultraviolet radiation, aerosol radiative parameters） and by using radiative and chemical models. A case study shows that the aerosol concentrations and UV radiation are significantly correlated with ozone concentrations. The correlation coefficient between the aerosol optical depth （AOD） and the PM10 mass concentration is very high, with a maximum of 0.98, and the AOD and UV radiation/ozone is anti- correlated, with a correlation coefficient of-0.90. The analysis suggests that ozone productivity is significantly decreased due to the reduction of UV radiation. The noon-time ozone maximum is considerably depressed when AOD is 0.6, and is further decreased when AOD is up to 1.2 due to the reduction of ozone photochemical productivity. Because the occurring probability of aerosol optical depth for AOD550m≥0.6 and AOD340mm ≥1.0 is 47, and 55% respectively during the dry season （October, November, December, January）, this heavy aerosol condition explains the low ozone maximum that often occurs in the dry season over the Guangzhou region. The analysis also suggests that the value of single scattering albedo （SSA） is very sensitive to the aerosol radiative effect when the radiative and chemical models are applied, implying that the value of SSA needs to be carefully studied when the models are used in calculating ozone production.展开更多
The goal of ecological civilization construction is to realize the harmonious coexistence of human and nature.Land is the spatial carrier of ecological civilization construction.Land use types or behaviors reflect the...The goal of ecological civilization construction is to realize the harmonious coexistence of human and nature.Land is the spatial carrier of ecological civilization construction.Land use types or behaviors reflect the level of intensive use of land resources,leading to different ecological environmental effects,thereby affecting the level of regional ecological civilization construction.This issue,"Land Use and Ecological Civilization",discusses the theory and method of land use management in the view of ecological civilization from the aspects of land use efficiency,land use change,land multi-functional trade-off,land ecosystem service and land ecological risk by selecting 14 representative papers,providing practical reference for the formation of the land use mode and behavioral system of ecological civilization.With abundant research levels,this issue covers varied research scales such as village,county and province,various landform types such as plain and hill,and typical land use areas at home and abroad such as East China,Central China,Northwest China,Yangtze River Economic Belt and Japan.Being frontier and practical,the multidisciplinary research methods in this issue include literature research method,fractal theory,qualitative comparative analysis,VAR model,and econometrics,among others.Focusing on the prominent problems in the process of land use,this issue deeply discusses the hot topics such as land ecological efficiency,spatial behavior characteristics,land use structure optimization and ecological risk assessment.This issue not only reviews the current literature on urgent land use issues such as arable land abandonment and land use risk,but also tries to conduct trade-off and synergy analysis on the varied functions of the rural landscape and ecosystem,thus providing a theoretical and empirical basis for solving land use problems from the perspective of ecological civilization.This issue reflects the realistic urgency of guiding land use with the concept of ecological civilization,and provides theoretical guidance and technical support from the aspects of methods and research framework.Finally,this issue proposes five hot topics in the field of land use research from the perspective of ecological civilization in the future,namely,ecological management of land use structure,ecological evolution mechanism of land use process,land ecological use mode,early warning and regulation of land ecological security pattern,ecological management and control of land use behavior.展开更多
文摘Today＇s production systems are demanded to exhibit an increased flexibility and mutability in order to deal with dynamically changing conditions, objectives and an increasing number of product variants within industrial turbulent environments. Flexible automated systems are requested in order to improve dynamic production efficiency, e.g. robot-based hardware and PC-based controllers, but these usually induce a significantly higher production complexity, whereby the efforts for planning and programming, but also setups and reconfiguration, expand. In this paper a definition and some concepts of self-optimizing assembly systems are presented to describe possible ways to reduce the planning efforts in complex production systems. The concept of self-optimization in assembly systems will be derived from a theoretical approach and will be transferred to a specific application scenario---the automated assembly of a miniaturized solid state laser--where the challenges of unpredictable influences from e.g. component tolerances can be overcome by the help of self-optimization.
基金supported by National Natural Science Foundation of China (Grant Nos. 40875090, 40375002, 40775011)Natural Science Foundation of Guangdong Province (Grant No. 7035008)Tropical Marine Meteorological Science Foundation (Grant No. 200502)
文摘Our analysis of the surface aerosol and ultraviolet （UV） measurements in Pearl River Delta （PRD） region shows that the surface UV radiation is reduced by more than 50% due to high aerosol concentrations. This has important impacts on urban ecosystem and photochemistry, especially on ozone photochemical production over the region. The quantitative effect of aerosols on surface ozone is evaluated by analyzing surface observations （including ozone, ultraviolet radiation, aerosol radiative parameters） and by using radiative and chemical models. A case study shows that the aerosol concentrations and UV radiation are significantly correlated with ozone concentrations. The correlation coefficient between the aerosol optical depth （AOD） and the PM10 mass concentration is very high, with a maximum of 0.98, and the AOD and UV radiation/ozone is anti- correlated, with a correlation coefficient of-0.90. The analysis suggests that ozone productivity is significantly decreased due to the reduction of UV radiation. The noon-time ozone maximum is considerably depressed when AOD is 0.6, and is further decreased when AOD is up to 1.2 due to the reduction of ozone photochemical productivity. Because the occurring probability of aerosol optical depth for AOD550m≥0.6 and AOD340mm ≥1.0 is 47, and 55% respectively during the dry season （October, November, December, January）, this heavy aerosol condition explains the low ozone maximum that often occurs in the dry season over the Guangzhou region. The analysis also suggests that the value of single scattering albedo （SSA） is very sensitive to the aerosol radiative effect when the radiative and chemical models are applied, implying that the value of SSA needs to be carefully studied when the models are used in calculating ozone production.
基金National Natural Science Foundation of China(41971243)The Science and Technology Project of Education Department in Jiangxi Province(GJJ200531)。
文摘The goal of ecological civilization construction is to realize the harmonious coexistence of human and nature.Land is the spatial carrier of ecological civilization construction.Land use types or behaviors reflect the level of intensive use of land resources,leading to different ecological environmental effects,thereby affecting the level of regional ecological civilization construction.This issue,"Land Use and Ecological Civilization",discusses the theory and method of land use management in the view of ecological civilization from the aspects of land use efficiency,land use change,land multi-functional trade-off,land ecosystem service and land ecological risk by selecting 14 representative papers,providing practical reference for the formation of the land use mode and behavioral system of ecological civilization.With abundant research levels,this issue covers varied research scales such as village,county and province,various landform types such as plain and hill,and typical land use areas at home and abroad such as East China,Central China,Northwest China,Yangtze River Economic Belt and Japan.Being frontier and practical,the multidisciplinary research methods in this issue include literature research method,fractal theory,qualitative comparative analysis,VAR model,and econometrics,among others.Focusing on the prominent problems in the process of land use,this issue deeply discusses the hot topics such as land ecological efficiency,spatial behavior characteristics,land use structure optimization and ecological risk assessment.This issue not only reviews the current literature on urgent land use issues such as arable land abandonment and land use risk,but also tries to conduct trade-off and synergy analysis on the varied functions of the rural landscape and ecosystem,thus providing a theoretical and empirical basis for solving land use problems from the perspective of ecological civilization.This issue reflects the realistic urgency of guiding land use with the concept of ecological civilization,and provides theoretical guidance and technical support from the aspects of methods and research framework.Finally,this issue proposes five hot topics in the field of land use research from the perspective of ecological civilization in the future,namely,ecological management of land use structure,ecological evolution mechanism of land use process,land ecological use mode,early warning and regulation of land ecological security pattern,ecological management and control of land use behavior.
