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| 2. |
- Liu, Yan, et al.
(författare)
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Ocean-driven thinning enhances iceberg calving and retreat of Antarctic ice shelves
- 2015
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 112:11, s. 3263-3268
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Tidskriftsartikel (refereegranskat)abstract
- Iceberg calving from all Antarctic ice shelves has never been directly measured, despite playing a crucial role in ice sheet mass balance. Rapid changes to iceberg calving naturally arise from the sporadic detachment of large tabular bergs but can also be triggered by climate forcing. Here we provide a direct empirical estimate of mass loss due to iceberg calving and melting from Antarctic ice shelves. We find that between 2005 and 2011, the total mass loss due to iceberg calving of 755 +/- 24 gigatonnes per year (Gt/y) is only half the total loss due to basal melt of 1516 +/- 106 Gt/y. However, we observe widespread retreat of ice shelves that are currently thinning. Net mass loss due to iceberg calving for these ice shelves (302 +/- 27 Gt/y) is comparable in magnitude to net mass loss due to basal melt (312 +/- 14 Gt/y). Moreover, we find that iceberg calving from these decaying ice shelves is dominated by frequent calving events, which are distinct from the less frequent detachment of isolated tabular icebergs associated with ice shelves in neutral or positive mass balance regimes. Our results suggest that thinning associated with ocean-driven increased basal melt can trigger increased iceberg calving, implying that iceberg calving may play an overlooked role in the demise of shrinking ice shelves, and is more sensitive to ocean forcing than expected from steady state calving estimates.
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| 3. |
- Chen, Silan, et al.
(författare)
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Interaction relationship between urban domestic energy consumption and water use - a case study of Beijing and Shanghai
- 2016
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Ingår i: Water Policy. - : IWA Publishing. - 1366-7017 .- 1996-9759. ; 18:3, s. 670-684
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Tidskriftsartikel (refereegranskat)abstract
- Energy consumption and water use are inextricably linked. Combining research on energy consumption and water use in an urban context provides a scientific basis for the integrated planning of energy and water supply systems. Domestic energy and water are among the most consumed resources in urban environments. Furthermore, domestic resources represent an increasing proportion of the total resources consumed. This paper explores four key indicators of urban energy consumption (UEC) and water use in Beijing and Shanghai for the period of 2000 to 2011. Using correlation analysis, this study establishes the intrinsic relationship between UEC and water use. It also offers an analysis of the consumption trends of these two resources as well as their interactive relationship. The results show that urban domestic energy consumption (UDEC) and water use have a significant linear correlation: UDEC is positively correlated with water use, and the correlation coefficients of Beijing and Shanghai are 0.81 and 0.97, respectively. In Beijing, urban domestic energy and water use per capita are negatively correlated, with the high correlation coefficient of 0.93. In Shanghai, urban domestic energy and water use per capita are positively correlated, with the correlation coefficient of 0.90.
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| 4. |
- Fu, Jiahong, et al.
(författare)
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Application of artificial neural network to forecast engine performance and emissions of a spark ignition engine
- 2022
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 201
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Tidskriftsartikel (refereegranskat)abstract
- Increasing the application of machine learning algorithms in engine development has the potential to reduce the number of experimental runs and the computation cost of computational fluid dynamics simulations. The objective of this study is to assess if such a statistical modelling approach can predict engine efficiency and emissions at any given condition for an already calibrated spark ignition (SI) engine. Engine responses at various engine speeds and load are recorded and used for correlative modelling. The artificial neural network (ANN) algorithm is utilized in this study, with engine speed and load as the model inputs, and fuel consumption and emission as the model outputs. The comparisons between experimentally measured data and model predictions indicate that the well-trained network is capable of forecasting engine efficiency, unburned hydrocarbons, carbon monoxide, and nitrogen oxide emissions with close-to-zero root mean squared error performance metric. In addition, the relatively small errors do not affect the relations between model inputs and outputs, as evidenced by the close-to-unity coefficient of determination. Overall, all these results indicate ANN model is appropriate for the application investigated in this study. Moreover, this study also suggests that the “black-box” modelling approach has the potential to effectively predict engine-related variables. And the predicted engine map can be used as a reference to accelerate the motor development in the hybrid vehicles. Also, the ANN model forecast the fuel consumption and emissions under transient operating conditions, while the literature is scarce to date on the investigation of the prediction of engine responses for transient conditions.
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| 5. |
- Fu, Li, et al.
(författare)
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Effects of long-term exposure to ambient fine particulate matter and its specific components on blood pressure and hypertension incidence
- 2024
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Ingår i: Environment International. - 0160-4120 .- 1873-6750. ; 184
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Tidskriftsartikel (refereegranskat)abstract
- Background: Epidemiological evidence on the association of PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 μm) and its specific components with hypertension and blood pressure is limited. Methods: We applied information of participants from the World Health Organization's (WHO) Study on Global Ageing and Adult Health (SAGE) to estimate the associations of long-term PM2.5 mass and its chemical components exposure with blood pressure (BP) and hypertension incidence in Chinese adults ≥ 50 years during 2007–2018. Generalized linear mixed model and Cox proportional hazard model were applied to investigate the effects of PM2.5 mass and its chemical components on the incidence of hypertension and BP, respectively. Results: Each interquartile range (IQR = 16.80 μg/m3) increase in the one-year average of PM2.5 mass concentration was associated with a 17 % increase in the risk of hypertension (HR = 1.17, 95 % CI: 1.10, 1.24), and the population attributable fraction (PAF) was 23.44 % (95 % CI: 14.69 %, 31.55 %). Each IQR μg/m3 increase in PM2.5 exposure was also related to increases of systolic blood pressure (SBP) by 2.54 mmHg (95 % CI:1.99, 3.10), and of diastolic blood pressure (DBP) by 1.36 mmHg (95 % CI: 1.04, 1.68). Additionally, the chemical components of SO42−, NO3−, NH4+, OM, and BC were also positively associated with an increased risk of hypertension incidence and elevated blood pressure. Conclusions: These results indicate that long-term exposure to PM2.5 mass and its specific components may be major drivers of escalation in hypertension diseases.
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| 6. |
- Gao, Xuerui, et al.
(författare)
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Feasibility evaluation of solar photovoltaic pumping irrigation system based on analysis of dynamic variation of groundwater table
- 2013
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 105, s. 182-193
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Tidskriftsartikel (refereegranskat)abstract
- Solar photovoltaic (PV) pumping irrigation system has become a widely applied solar energy technology over the past decades, in which the pump is driven by electricity produced by solar energy and lifts groundwater or surface water to irrigate the crop or grassland for agriculture. Qinghai Province, located in the Qinghai-Tibet Plateau, features abundant solar energy, but the problem of local grassland degradation and ecological deterioration has become increasingly serious. Using the clean solar energy to pump groundwater or surface water is of great significance for grassland recovery, environment protection and ecological restoration. In this study, we selected a demonstration site (with an area of 3.15 ha) in Tibetan Autonomous Prefecture of Golog at the southern part of Qinghai Province and evaluated the feasibility and performance of the PV pumping irrigation system at field scale. Firstly, water demand of pasture was predicted in different hydrological level years to determine water deficiency, which should be replenished mainly by pumping groundwater according to the local water resources conditions. Secondly, through modeling the unsteady flow of partially penetrating well in unconfined aquifer, we analyzed the change of groundwater table of the pumping well in both irrigation season and non-irrigation season, and then evaluated whether the groundwater resources can satisfy the pumping water demand for the growth of grassland. Results show that groundwater resources in the demonstration area are satisfactory and water yield in the pumping well can generally fulfill the water demand of grassland. Finally, based on balance analysis between solar energy supply and demand, a set of technical parameters were given to design the PV pumping irrigation system in the demonstration area. We also made the benefit analysis for the PV pumping irrigation system. It is concluded that, the PV system has good economic and ecological performance in the demonstration site compared to the diesel engine irrigation system, showing promising prospects to be popularized in Western China at large scale.
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| 7. |
- Liu, Jiahong, et al.
(författare)
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Evolution of China's urban energy consumption structure-a case study in Beijing
- 2016
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Ingår i: CUE 2015 - APPLIED ENERGY SYMPOSIUM AND SUMMIT 2015. - : Elsevier BV. ; 88, s. 88-93
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Konferensbidrag (refereegranskat)abstract
- China is a coal-based energy consuming country. The proportion of coal is up to 70% in the energy consumption structure in 1990s. In the past 20 years, driven by energy saving policy, China's energy consumption structure has undergone great changes, especially in urban areas. This paper explores the evolution of energy-use structure at the national level and the level of Beijing City in China. Four major energy sources were considered, including coal, oil, natural gas and electricity. The dataset was collected from 1990 to 2012. The results show that the proportion of coal consumption decreased by approximately 20% from 1990 to 2012 at the national level in compare with nearly 50% at the level of Beijing City. Furthermore, the proportion of natural gas consumption and other clean energies rose. In Beijing the natural gas and other clean energies account for over 60% of the total energy in 2012, which played an important role in improving the local environment.
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| 8. |
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| 9. |
- Yuan, Feifei, et al.
(författare)
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Changes in precipitation extremes over the source region of the Yellow River and its relationship with teleconnection patterns
- 2020
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Ingår i: Water. - 2073-4441. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Precipitation extremes and their underlying causes are important processes to understand to plan appropriate adaptation measures. This paper presents an analysis of the spatiotemporal variability and trend of precipitation extremes in the important source region of the Yellow River and explores the connection to global teleconnection patterns and the 850-mb vector wind. Six indices for precipitation extremes were computed and analyzed for assessment of a changing regional climate. Results showed that these indices have a strong gradient from the northwest to the southeast part for the period 1961-2015, due to the great influence from the south-easterly summer monsoon flow. However, no statistically significant trends were found for the defined indices at the majority of stations, and their spatial distribution are noticed by irregularly mixed positive and negative changes except for the maximum number of consecutive wet days (CWD). Singular value decomposition analysis revealed that the precipitation extreme indices-including annual total precipitation when daily precipitation >95th percentile (R95p), annual count of days with daily precipitation ≥10 mm (R10mm), annual maximum consecutive 5-day precipitation (R5d), total precipitation divided by the number of wet days (SDII), and CWD-are negatively related to the El Nino-Southern Oscillation (NINO 3.4) in the first mode, and the maximum number of consecutive dry days (CDD) is positively related to the Scandinavian pattern in the second mode at 0.05 significance level. The 850-mb vector wind analysis showed that the southwestern monsoon originating from the Indian Ocean brings sufficient moisture to this region. Furthermore, the anti-cyclone in the western part of the North Pacific plays a significant role in the transport of moisture to the source region of the Yellow River. The links between precipitation extremes and teleconnection patterns explored in this study are important for better prediction and preparedness of climatic extremes.
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