It has been demonstrated that almost all polymer-clay nanocomposites show higher temperature stability than that of pure polymer,which is attributed to the active exfoliated clay nanosheet firmly adsorbed onto the pol...It has been demonstrated that almost all polymer-clay nanocomposites show higher temperature stability than that of pure polymer,which is attributed to the active exfoliated clay nanosheet firmly adsorbed onto the polymer chains,due to polerization and nucleation effect,the clay nanosheets could protect the polymer chains from destroying.To prove such mechanism,the water-soluble polymer nanocomposites(AAA/SLS-MMT)were synthesized by the in-situ polymerization of 2-acrylamide-2-methyl-propane sulfonic acid,acrylamide,4-acryloylmorpholine,and organically modified montmorillonite.The techniques of nuclear magnetic resonance,atomic force microscopy and scanning electron microscopy etc.,clearly characterized the successful synthesized of sample's structure,the exfoliated MMT nanosheet adsorbed polymer chain's scale,and well-dispersed morphology,espectively.The adsorption model,X-ray photoelectron spectroscopy presented the existence of strong adsorption,while molecular simulation calculations first concluded that the strong adsorption energy was-13032.06 kcal/mol.Thermo-gravimetric-analysis proved the temperature of maximum thermal degradation of powder sample(AAA/1.0 wt%SLS-MMT)was over 298℃.After ageing at 180℃for 4 h,the apparent viscosity of 5 g/L AAA/1.0 wt%SLS-MMT aqueous solution was 326.7 mPa,s,while that of pure polymer(AAA)was only 8.3 mPa,s.This optimized sample has the smallest FLAPIvalue at all test temperatures from 180 to 220℃in both fresh and salt water based drilling fluid.All the evidences of high temperature resistance indicate that the strong adsorption can enhance the thickness of hydrated shell and adsorption of clay particles in drilling fluid at high temperature.Such mechanism supplied the better way to design high-temperature resistant fluid loss additives for deep and ultra-deep oil and gas formation engineering.展开更多
Atmospheric inversion phenomenon directly affects the vertical movement of air, which causes the cooling heat of the cooling tower in the power plant to be blocked. Therefore, it is necessary to analyze the atmospheri...Atmospheric inversion phenomenon directly affects the vertical movement of air, which causes the cooling heat of the cooling tower in the power plant to be blocked. Therefore, it is necessary to analyze the atmospheric inversion characteristics of the research project during the design of the air cooling system. Using the low-altitude observing system of the tethered balloon, the on-site observation of the temperature below 300 m in summer is carried out for a coal-fired power integration project in Yulin, Shaanxi, China. Observations were made at 10 fixed times per day, with a cumulative observation of 46 days and 247 effective detections. The data were quality-controlled, and then linearly interpolated. According to the requirements of the project designer, the temperature data of 20, 50, 100, 150, 200, 250, 300 m was used for low-temperature inversion analysis. The research shows that the grounding inversion and low-altitude inversion can be observed at the same time. In the time and space changes, the grounding inversion temperature and intensity are significantly higher than the low-altitude inversion. The maximum inversion of grounding inversion and low-altitude inversion is 2.3?C/hm, 1.0?C/hm. Grounding inversion temperature occurs every time, the frequency is the highest at 20 o’clock, the average intensity is maximum at 17 o’clock, and the average height, maximum intensity and maximum height are maximum at 7 o’clock. When the low-altitude inversion temperature is 18 o’clock, other times can occur, and the frequency is the highest at 15 o’clock, but the inversion layer is shallow, the bottom is high and the intensity is small. Grounding inversion and low-altitude inversion can occur in all levels, and as the height increases, the grounding inversion decreases and the low-temperature inversion increases. The design of the project air cooling tower needs to fully consider the impact caused by the inverse temperature below 300 m.展开更多
Purpose: To design an efficient high-performance algorithm for semantic annotation of biodiversity documents in Chinese.Design/methodology/approach: Data set consists of 1,000 randomly selected documents from Flora of...Purpose: To design an efficient high-performance algorithm for semantic annotation of biodiversity documents in Chinese.Design/methodology/approach: Data set consists of 1,000 randomly selected documents from Flora of China. Comparative evaluation of the proposed approach with the Na ve Bayes algorithm have been developed before for the same purpose.Findings: Experimental results show that the heuristics based algorithm outperformed the Na ve Bayes algorithm. The use of leading words helped improving the annotation performance while prioritizing rule application based on their weights had no significant impact on algorithm performance.Research limitations: The ICTCLAS was used to identify word boundaries off-shelf without optimatization for biodiversity domain. This may have not made the best use of the tool.Practical implications & Originality/value: The performance of heuristics based approach,enhanced by leading words analysis, reached an F value of 0.9216, which is sufficiently accurate for practical use.展开更多
基金financially supported by the National Major Project(No.2017ZX05009-003,50)National Natural Science Foundation of China(No.51974339+2 种基金51674270)Foreign Expert Project of the Belt and Road Innovation Talents Exchange(DL2022122001)the Research Institute of Petroleum Exploration Development of China National Petroleum Cooperation(HX20201095)。
文摘It has been demonstrated that almost all polymer-clay nanocomposites show higher temperature stability than that of pure polymer,which is attributed to the active exfoliated clay nanosheet firmly adsorbed onto the polymer chains,due to polerization and nucleation effect,the clay nanosheets could protect the polymer chains from destroying.To prove such mechanism,the water-soluble polymer nanocomposites(AAA/SLS-MMT)were synthesized by the in-situ polymerization of 2-acrylamide-2-methyl-propane sulfonic acid,acrylamide,4-acryloylmorpholine,and organically modified montmorillonite.The techniques of nuclear magnetic resonance,atomic force microscopy and scanning electron microscopy etc.,clearly characterized the successful synthesized of sample's structure,the exfoliated MMT nanosheet adsorbed polymer chain's scale,and well-dispersed morphology,espectively.The adsorption model,X-ray photoelectron spectroscopy presented the existence of strong adsorption,while molecular simulation calculations first concluded that the strong adsorption energy was-13032.06 kcal/mol.Thermo-gravimetric-analysis proved the temperature of maximum thermal degradation of powder sample(AAA/1.0 wt%SLS-MMT)was over 298℃.After ageing at 180℃for 4 h,the apparent viscosity of 5 g/L AAA/1.0 wt%SLS-MMT aqueous solution was 326.7 mPa,s,while that of pure polymer(AAA)was only 8.3 mPa,s.This optimized sample has the smallest FLAPIvalue at all test temperatures from 180 to 220℃in both fresh and salt water based drilling fluid.All the evidences of high temperature resistance indicate that the strong adsorption can enhance the thickness of hydrated shell and adsorption of clay particles in drilling fluid at high temperature.Such mechanism supplied the better way to design high-temperature resistant fluid loss additives for deep and ultra-deep oil and gas formation engineering.
文摘Atmospheric inversion phenomenon directly affects the vertical movement of air, which causes the cooling heat of the cooling tower in the power plant to be blocked. Therefore, it is necessary to analyze the atmospheric inversion characteristics of the research project during the design of the air cooling system. Using the low-altitude observing system of the tethered balloon, the on-site observation of the temperature below 300 m in summer is carried out for a coal-fired power integration project in Yulin, Shaanxi, China. Observations were made at 10 fixed times per day, with a cumulative observation of 46 days and 247 effective detections. The data were quality-controlled, and then linearly interpolated. According to the requirements of the project designer, the temperature data of 20, 50, 100, 150, 200, 250, 300 m was used for low-temperature inversion analysis. The research shows that the grounding inversion and low-altitude inversion can be observed at the same time. In the time and space changes, the grounding inversion temperature and intensity are significantly higher than the low-altitude inversion. The maximum inversion of grounding inversion and low-altitude inversion is 2.3?C/hm, 1.0?C/hm. Grounding inversion temperature occurs every time, the frequency is the highest at 20 o’clock, the average intensity is maximum at 17 o’clock, and the average height, maximum intensity and maximum height are maximum at 7 o’clock. When the low-altitude inversion temperature is 18 o’clock, other times can occur, and the frequency is the highest at 15 o’clock, but the inversion layer is shallow, the bottom is high and the intensity is small. Grounding inversion and low-altitude inversion can occur in all levels, and as the height increases, the grounding inversion decreases and the low-temperature inversion increases. The design of the project air cooling tower needs to fully consider the impact caused by the inverse temperature below 300 m.
基金supported by the National Social Science Foundation of China (Grant No.:11BTQ024)the Foundation for Humanities and Social Sciences of the Chinese Ministry of Education (Grant No.:10YJC87004)
文摘Purpose: To design an efficient high-performance algorithm for semantic annotation of biodiversity documents in Chinese.Design/methodology/approach: Data set consists of 1,000 randomly selected documents from Flora of China. Comparative evaluation of the proposed approach with the Na ve Bayes algorithm have been developed before for the same purpose.Findings: Experimental results show that the heuristics based algorithm outperformed the Na ve Bayes algorithm. The use of leading words helped improving the annotation performance while prioritizing rule application based on their weights had no significant impact on algorithm performance.Research limitations: The ICTCLAS was used to identify word boundaries off-shelf without optimatization for biodiversity domain. This may have not made the best use of the tool.Practical implications & Originality/value: The performance of heuristics based approach,enhanced by leading words analysis, reached an F value of 0.9216, which is sufficiently accurate for practical use.
