Exploring the spatiotemporal changes in Fractional Vegetation Coverage(FVC)helps to more accurately understand the quality of the ecological environment,which is of great significance for regional ecological protectio...Exploring the spatiotemporal changes in Fractional Vegetation Coverage(FVC)helps to more accurately understand the quality of the ecological environment,which is of great significance for regional ecological protection and sustainable economic development.The study takes the Chengdu-Chongqing urban agglomeration as the research area,analyzes the characteristics and trends of vegetation cover changes from 2000 to 2020 using the Google Earth Engine cloud platform,and explores its driving factors based on the enhanced regression tree model.The results show that:(1)From 2000 to 2020,the annual FVC of the Chengdu-Chongqing urban agglomeration showed a fluctuating upward trend,with a stable phase from 2000 to 2003 and an upward phase from 2003 to 2020.(2)During the research period,most areas within the agglomeration exhibited negligible changes in FVC.In contrast,other areas showed a complex pattern of both vegetation degradation and improvement.The areas with improved FVC were sporadically distributed,accounting for 15.08% of the total area,whereas areas with substantial vegetation degradation constituted 11.60%.(3)The FVC in the Chengdu-Chongqing urban agglomeration is predominantly influenced by four key factors:population dynamics,forestrymanagement practices,annual sunshine duration,and annual precipitation.Collectively,these factors account for 99.31%of the variation in FVC,with anthropogenic factors(population dynamics and forestry management)exerting the most significant influence.展开更多
This paper introduces the idea of a framework for the implementation of novel downhole probes. A couple of examples （e.g. a tracer detector, a casing smear test probe or a casing repair probe） demonstrate that many ...This paper introduces the idea of a framework for the implementation of novel downhole probes. A couple of examples （e.g. a tracer detector, a casing smear test probe or a casing repair probe） demonstrate that many components can be reused. These are the ＂bricks＂ of the ZWERG toolkit which is developed to match the environment in boreholes. Two ＂bricks＂ are described in detail： The housing （1） has to resist the pressure and other mechanical stress in deep holes. The selection of the material and the calculation of the wall thickness are the main interests. In many applications, a thermal management （2） of the inside of the probe is absolutely necessary. A dewar vessel can uncouple the heat of the geothermal reservoir and the temperature in the probe. It is important to understand the physical heat flow mechanisms. A set of formulas allows a good estimation of the quantity of heat that warms up the probe. The toolkit contains some immaterial ＂bricks＂ like blueprints of proven designs or support for the logistic process of finding and purchasing compatible components. The intention to drill near magma chambers calls for a common eflbrt of the geothermal community to gather compatible components, assemblies and knowhow and makes it widely available. ZWERG could be a starting point.展开更多
基金supported by the Sichuan Science and Technology Program(Grant No.2023NSFSC0250).
文摘Exploring the spatiotemporal changes in Fractional Vegetation Coverage(FVC)helps to more accurately understand the quality of the ecological environment,which is of great significance for regional ecological protection and sustainable economic development.The study takes the Chengdu-Chongqing urban agglomeration as the research area,analyzes the characteristics and trends of vegetation cover changes from 2000 to 2020 using the Google Earth Engine cloud platform,and explores its driving factors based on the enhanced regression tree model.The results show that:(1)From 2000 to 2020,the annual FVC of the Chengdu-Chongqing urban agglomeration showed a fluctuating upward trend,with a stable phase from 2000 to 2003 and an upward phase from 2003 to 2020.(2)During the research period,most areas within the agglomeration exhibited negligible changes in FVC.In contrast,other areas showed a complex pattern of both vegetation degradation and improvement.The areas with improved FVC were sporadically distributed,accounting for 15.08% of the total area,whereas areas with substantial vegetation degradation constituted 11.60%.(3)The FVC in the Chengdu-Chongqing urban agglomeration is predominantly influenced by four key factors:population dynamics,forestrymanagement practices,annual sunshine duration,and annual precipitation.Collectively,these factors account for 99.31%of the variation in FVC,with anthropogenic factors(population dynamics and forestry management)exerting the most significant influence.
文摘This paper introduces the idea of a framework for the implementation of novel downhole probes. A couple of examples （e.g. a tracer detector, a casing smear test probe or a casing repair probe） demonstrate that many components can be reused. These are the ＂bricks＂ of the ZWERG toolkit which is developed to match the environment in boreholes. Two ＂bricks＂ are described in detail： The housing （1） has to resist the pressure and other mechanical stress in deep holes. The selection of the material and the calculation of the wall thickness are the main interests. In many applications, a thermal management （2） of the inside of the probe is absolutely necessary. A dewar vessel can uncouple the heat of the geothermal reservoir and the temperature in the probe. It is important to understand the physical heat flow mechanisms. A set of formulas allows a good estimation of the quantity of heat that warms up the probe. The toolkit contains some immaterial ＂bricks＂ like blueprints of proven designs or support for the logistic process of finding and purchasing compatible components. The intention to drill near magma chambers calls for a common eflbrt of the geothermal community to gather compatible components, assemblies and knowhow and makes it widely available. ZWERG could be a starting point.
