This paper reports the on-site performance evaluation of conventional and improved gas engine-driven VRF （variable refrigerant flow） units and （abbreviated as GHP） units. The study aims to elucidate two actual GHP...This paper reports the on-site performance evaluation of conventional and improved gas engine-driven VRF （variable refrigerant flow） units and （abbreviated as GHP） units. The study aims to elucidate two actual GHP units by using the probe insertion method. There is a tendency to decrease energy efficiency compared to a high loading factor. GHP operation was almost all part load operation. This on-site evaluation indicates a clear difference between conventional and improved GHP.展开更多
Quantitative evaluation and driving mechanism analysis of vegetation dynamics are essential for promoting regional sustainable development.In the past 20 years,the ecological environment in Altay Prefecture has change...Quantitative evaluation and driving mechanism analysis of vegetation dynamics are essential for promoting regional sustainable development.In the past 20 years,the ecological environment in Altay Prefecture has changed significantly due to global warming.Meanwhile,with increasing human activities,the spatiotemporal pattern and driving forces of vegetation variation in the area are uncertain and difficult to accurately assess.Hence,we quantified the vegetation growth by using the Normalized Difference Vegetation Index(NDVI)on the Google Earth Engine(GEE).Then,the spatiotemporal patterns of vegetation from 2000 to 2019 were analyzed at the pixel scale.Finally,significance threshold segmentation was performed using meteorological data based on the correlation analysis results,and the contributions of climate change and human activities to vegetation variation were quantified.The results demonstrated that the vegetation coverage in Altay Prefecture is mainly concentrated in the north.The vegetation areas representing significant restoration and degradation from 2000 to 2019 accounted for 24.08% and 1.24% of Altay Prefecture,respectively.Moreover,spatial correlation analysis showed that the areas with significant correlations between NDVI and temperature,precipitation and sunlight hours accounted for 3.3%,6.9% and 20.3% of Altay Prefecture,respectively.In the significant restoration area,18.94% was dominated by multiple factors,while 3.4% was dominated by human activities,and 1.74% was dominated by climate change.Within the significant degradation area,abnormal degradation and climate change controlled 1.07% and 0.17%,respectively.This study revealed the dynamic changes of vegetation and their driving mechanisms in Altay Prefecture,and can provide scientific support for further research on life community mechanism theory and key remediation technology of mountain-water-forest-farmland-lake-grass in Altay Prefecture.展开更多
文摘This paper reports the on-site performance evaluation of conventional and improved gas engine-driven VRF （variable refrigerant flow） units and （abbreviated as GHP） units. The study aims to elucidate two actual GHP units by using the probe insertion method. There is a tendency to decrease energy efficiency compared to a high loading factor. GHP operation was almost all part load operation. This on-site evaluation indicates a clear difference between conventional and improved GHP.
基金The Science and Technology Project of Xizang Autonomous Region(XZ201901-GA-07)The Key Research and Development Project of Sichuan Science and Technology Department(2021YFQ0042)The Science and Technology Bureau of Altay Region in Yili Kazak Autonomous Prefecture(Y99M4600AL)。
文摘Quantitative evaluation and driving mechanism analysis of vegetation dynamics are essential for promoting regional sustainable development.In the past 20 years,the ecological environment in Altay Prefecture has changed significantly due to global warming.Meanwhile,with increasing human activities,the spatiotemporal pattern and driving forces of vegetation variation in the area are uncertain and difficult to accurately assess.Hence,we quantified the vegetation growth by using the Normalized Difference Vegetation Index(NDVI)on the Google Earth Engine(GEE).Then,the spatiotemporal patterns of vegetation from 2000 to 2019 were analyzed at the pixel scale.Finally,significance threshold segmentation was performed using meteorological data based on the correlation analysis results,and the contributions of climate change and human activities to vegetation variation were quantified.The results demonstrated that the vegetation coverage in Altay Prefecture is mainly concentrated in the north.The vegetation areas representing significant restoration and degradation from 2000 to 2019 accounted for 24.08% and 1.24% of Altay Prefecture,respectively.Moreover,spatial correlation analysis showed that the areas with significant correlations between NDVI and temperature,precipitation and sunlight hours accounted for 3.3%,6.9% and 20.3% of Altay Prefecture,respectively.In the significant restoration area,18.94% was dominated by multiple factors,while 3.4% was dominated by human activities,and 1.74% was dominated by climate change.Within the significant degradation area,abnormal degradation and climate change controlled 1.07% and 0.17%,respectively.This study revealed the dynamic changes of vegetation and their driving mechanisms in Altay Prefecture,and can provide scientific support for further research on life community mechanism theory and key remediation technology of mountain-water-forest-farmland-lake-grass in Altay Prefecture.
