Heavy metal concentrations in urban soils are likely to increase over time because of contin-uous urbanization and heavy metal emissions.To estimate the accumulation rates of heavy metals in urban soils,we collected s...Heavy metal concentrations in urban soils are likely to increase over time because of contin-uous urbanization and heavy metal emissions.To estimate the accumulation rates of heavy metals in urban soils,we collected soil samples from residential areas with different build-ing ages in the metropolitan cities of Shanghai,Shenzhen,and Beijing,China.Heavy metal concentrations in the soils varied among the cities and were primarily affected by soil parent material and the intensity of anthropogenic sources.Regression analyses revealed that the accumulation rates of Cd and Cu in the soils ranged from 0.0034 to 0.0039 mg/(kg·year)and 0.343 to 0.391 mg/(kg·year),respectively,and were similar across the three cities,while ac-cumulation rates of Zn and Pb in Shanghai were higher than those in Shenzhen and Beijing.The higher accumulation rates of Zn and Pb in Shanghai can be explained by differences in city history and industrial structures among the cities.Residential soils with high health risks posed by the heavy metals were mostly collected from old towns of Shanghai because of high Pb content in the areas.Although recent urbanization resulted in elevated concen-trations of Cd,Cu,Zn,and Pb in the residential soils,the effect on the total health risks of residents exposed to the soils was negligible.展开更多
Rate of penetration(ROP)is the key factor affecting the drilling cycle and cost,and it directly reflects the drilling efficiency.With the increasingly complex field data,the original drilling parameter optimization me...Rate of penetration(ROP)is the key factor affecting the drilling cycle and cost,and it directly reflects the drilling efficiency.With the increasingly complex field data,the original drilling parameter optimization method can't meet the needs of drilling parameter optimization in the era of big data and artificial intelligence.This paper presents a drilling parameter optimization method based on big data of drilling,which takes machine learning algorithms as a tool.First,field data is pre-processed according to the characteristics of big data of drilling.Then a formation clustering model based on unsupervised learning is established,which takes sonic logging,gamma logging,and density logging data as input.Formation clusters with similar stratum characteristics are decided.Aiming at improving ROP,the formation clusters are input into the ROP model,and the mechanical parameters(weight on bit,revolution per minute)and hydraulic parameters(standpipe pressure,flow rate)are optimized.Taking the Southern Margin block of Xinjiang as an example,the MAPE of prediction of ROP after clustering is decreased from 18.72%to 10.56%.The results of this paper provide a new method to improve drilling efficiency based on big data of drilling.展开更多
Geothermal energy is a clean and ecologically friendly energy source with significant potential. The temperature variations between the Polycrystalline Diamond Compact (PDC) cutter and the rock of the reservoir are th...Geothermal energy is a clean and ecologically friendly energy source with significant potential. The temperature variations between the Polycrystalline Diamond Compact (PDC) cutter and the rock of the reservoir are the key factors affecting the cutting performance when drilling through formations with thermally damaged rock. To better investigate the temperature rise, a series of rock samples treated at high temperatures (9–300℃) were broken with a PDC cutter. The performance of the PDC cutter on these samples was studied using cutting force sensors, high-speed photography, and the thermal infrared imager. Based on the experimental data, a new cutting force evaluation parameter, η, is suggested. The link between the cutting force and rock properties is discussed in detail. The present results indicate that the average cutting force of high-temperature-treated granite is 3–5 times that of the thermally damaged sandstone. Furthermore, a critical temperature for thermal damage has been identified in granite cutting at 100–200℃ and in sandstone at 100℃. This corresponds to the temperature at which interlayer water loss and thermal crack closure occur. The results also indicate that when the treatment temperature exceeds the critical threshold, both the cutting force and temperature rise exhibit more significant changes with increasing temperature. Additionally, the maximum temperature of the PDC cutter during granite cutting can reach 47.6 ℃, which is almost 34℃ higher than that of sandstone. Regarding debris size, granite is much less sensitive to the treatment temperature, showing only slight changes in debris size compared to sandstone as the treatment temperature increases. The increasing cutter-rock interface area can significantly reduce frictional heat generation while increasing the cutting force and enhancing the temperature rise. The parameter valuation of the newly defined parameter η, which is related to frictional heating, shows that the capacity of the thermal generation and the heat transfer change as the temperature rises at the cutter-rock interface. At last, the correlation analysis indicates that the cutting force of sandstone and granite is highly correlated with , E/σc and σt. This study serves as a theoretical support and technical guidance for cutting hot dry rock (HDR), which is of great significance to HDR drilling.展开更多
The feasibility of aluminum recovery from secondary aluminum dross by extraction with NaOH solution and the subsequent synthesis of MgAl_2O_4 spinel by sintering the extracted slag were studied. The extraction percent...The feasibility of aluminum recovery from secondary aluminum dross by extraction with NaOH solution and the subsequent synthesis of MgAl_2O_4 spinel by sintering the extracted slag were studied. The extraction percentage of soluble aluminum from the dross reached 80% at a temperature of 353 K, liquid-to-solid ratio of 12 mL·g^(-1), stirring speed of 300 r·min^(-1), and an extraction time of 15 min; the hydrolysis percentage of AlN reached 40% with an extraction time of 30 min. The activation energies of the soluble aluminum and AlN extracted from the dross were 7.15 and 8.98 kJ·mol^(-1), respectively, indicating that their kinetics were controlled by outer diffusion without a product layer. The extracted slag was sintered in the temperature range 1373–1773 K; MgAl_2O_4 spinel with a compressive strength as high as 69.4 MPa was produced in the sample sintered at 1673 K for 3 h. This value exceeds the threshold(40 MPa) prescribed by the National Standard for the Magnesia and Magnesia-alumina Refractory Bricks of China(GB/T 2275-2007). These results establish the effectiveness of aluminum recovery from secondary aluminum dross and subsequent MgAl_2O_4 spinel synthesis.展开更多
基金We acknowledge the financial support provided by the National Natural Science Foundation of China(No.41771532).
文摘Heavy metal concentrations in urban soils are likely to increase over time because of contin-uous urbanization and heavy metal emissions.To estimate the accumulation rates of heavy metals in urban soils,we collected soil samples from residential areas with different build-ing ages in the metropolitan cities of Shanghai,Shenzhen,and Beijing,China.Heavy metal concentrations in the soils varied among the cities and were primarily affected by soil parent material and the intensity of anthropogenic sources.Regression analyses revealed that the accumulation rates of Cd and Cu in the soils ranged from 0.0034 to 0.0039 mg/(kg·year)and 0.343 to 0.391 mg/(kg·year),respectively,and were similar across the three cities,while ac-cumulation rates of Zn and Pb in Shanghai were higher than those in Shenzhen and Beijing.The higher accumulation rates of Zn and Pb in Shanghai can be explained by differences in city history and industrial structures among the cities.Residential soils with high health risks posed by the heavy metals were mostly collected from old towns of Shanghai because of high Pb content in the areas.Although recent urbanization resulted in elevated concen-trations of Cd,Cu,Zn,and Pb in the residential soils,the effect on the total health risks of residents exposed to the soils was negligible.
文摘现有基于人工智能的电缆故障诊断方法缺乏处理故障动态差异化发展的能力,其不能适应新的故障场景,无法随着时间的推移增强诊断能力。鉴于此,在深度卷积神经网络(deep convolutional neural network,DCNN)的基础上,融合知识蒸馏与注意力机制提出一种电缆故障可扩展化诊断方法(DCNN with knowledge distillation and attention,DCNN-KD-A)。引入知识蒸馏思想,保留DCNN模型对原有故障的诊断信息,同时利用新增故障的分类损失对模型进行拓展修正,使其具备故障可扩展化诊断的能力。为避免模型训练中的灾难性遗忘问题,重新构建了相适应的故障分类器。为应对知识蒸馏中的信息损耗与改变,利用注意力机制增强模型的特征凝练作用,提升其可扩展化诊断精度。通过实测与仿真数据进行实验,实验结果验证了所提方法的有效性和可行性。
基金financially supported by Sichuan Science and Technology Program(No.2025ZNSFSC0373)National Natural Science foundation of China(Grant No.52104006)Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(Grant No.2020CX040202)。
文摘Rate of penetration(ROP)is the key factor affecting the drilling cycle and cost,and it directly reflects the drilling efficiency.With the increasingly complex field data,the original drilling parameter optimization method can't meet the needs of drilling parameter optimization in the era of big data and artificial intelligence.This paper presents a drilling parameter optimization method based on big data of drilling,which takes machine learning algorithms as a tool.First,field data is pre-processed according to the characteristics of big data of drilling.Then a formation clustering model based on unsupervised learning is established,which takes sonic logging,gamma logging,and density logging data as input.Formation clusters with similar stratum characteristics are decided.Aiming at improving ROP,the formation clusters are input into the ROP model,and the mechanical parameters(weight on bit,revolution per minute)and hydraulic parameters(standpipe pressure,flow rate)are optimized.Taking the Southern Margin block of Xinjiang as an example,the MAPE of prediction of ROP after clustering is decreased from 18.72%to 10.56%.The results of this paper provide a new method to improve drilling efficiency based on big data of drilling.
基金supported by the National Natural Science Foundation of China(Grant No.52004236)the Key Program of National Natural Science Foundation of China(Grant No.52234003)+2 种基金Sichuan Provincial Returned Scholars'Scientific and Technological Activities Merit-based Funding Programs(Grant No.2023016)Open project of the International Joint Research Center for Deep Earth Drilling and Deep Earth Resources Development of the Ministry of Science and Technology(Grant No.DEDRD-2023-06)the National Natural Science Foundation of China Outstanding Youth Science Fund Program(Grant No.52222402).
文摘Geothermal energy is a clean and ecologically friendly energy source with significant potential. The temperature variations between the Polycrystalline Diamond Compact (PDC) cutter and the rock of the reservoir are the key factors affecting the cutting performance when drilling through formations with thermally damaged rock. To better investigate the temperature rise, a series of rock samples treated at high temperatures (9–300℃) were broken with a PDC cutter. The performance of the PDC cutter on these samples was studied using cutting force sensors, high-speed photography, and the thermal infrared imager. Based on the experimental data, a new cutting force evaluation parameter, η, is suggested. The link between the cutting force and rock properties is discussed in detail. The present results indicate that the average cutting force of high-temperature-treated granite is 3–5 times that of the thermally damaged sandstone. Furthermore, a critical temperature for thermal damage has been identified in granite cutting at 100–200℃ and in sandstone at 100℃. This corresponds to the temperature at which interlayer water loss and thermal crack closure occur. The results also indicate that when the treatment temperature exceeds the critical threshold, both the cutting force and temperature rise exhibit more significant changes with increasing temperature. Additionally, the maximum temperature of the PDC cutter during granite cutting can reach 47.6 ℃, which is almost 34℃ higher than that of sandstone. Regarding debris size, granite is much less sensitive to the treatment temperature, showing only slight changes in debris size compared to sandstone as the treatment temperature increases. The increasing cutter-rock interface area can significantly reduce frictional heat generation while increasing the cutting force and enhancing the temperature rise. The parameter valuation of the newly defined parameter η, which is related to frictional heating, shows that the capacity of the thermal generation and the heat transfer change as the temperature rises at the cutter-rock interface. At last, the correlation analysis indicates that the cutting force of sandstone and granite is highly correlated with , E/σc and σt. This study serves as a theoretical support and technical guidance for cutting hot dry rock (HDR), which is of great significance to HDR drilling.
基金financially supported by the National Natural Science Foundation of China (No. 21577176)the Environment Protection Scientific Research Project of Hunan Province, China (No. [2016]59-3)
文摘The feasibility of aluminum recovery from secondary aluminum dross by extraction with NaOH solution and the subsequent synthesis of MgAl_2O_4 spinel by sintering the extracted slag were studied. The extraction percentage of soluble aluminum from the dross reached 80% at a temperature of 353 K, liquid-to-solid ratio of 12 mL·g^(-1), stirring speed of 300 r·min^(-1), and an extraction time of 15 min; the hydrolysis percentage of AlN reached 40% with an extraction time of 30 min. The activation energies of the soluble aluminum and AlN extracted from the dross were 7.15 and 8.98 kJ·mol^(-1), respectively, indicating that their kinetics were controlled by outer diffusion without a product layer. The extracted slag was sintered in the temperature range 1373–1773 K; MgAl_2O_4 spinel with a compressive strength as high as 69.4 MPa was produced in the sample sintered at 1673 K for 3 h. This value exceeds the threshold(40 MPa) prescribed by the National Standard for the Magnesia and Magnesia-alumina Refractory Bricks of China(GB/T 2275-2007). These results establish the effectiveness of aluminum recovery from secondary aluminum dross and subsequent MgAl_2O_4 spinel synthesis.
