Emulsion of waxy crude oil is one of the common states in the subsea pipeline. At low temperatures in offshore environment, waxy crude oils with water could form the crude oil emulsion gel of oil-in-water emulsion. Th...Emulsion of waxy crude oil is one of the common states in the subsea pipeline. At low temperatures in offshore environment, waxy crude oils with water could form the crude oil emulsion gel of oil-in-water emulsion. Thus, the waxy crude oil emulsion viscoelastic behavior for deep sea transportation and restarting pipeline safety is particularly important. By means of MASIII HAAKE rheometer which is produced by German company, waxy crude oil emulsion viscoelastic behavior is explored at different volumetric water contents and different shear stresses. By analyzing the rate of change of shear rate in the initial stage, the influence rules of viscoelastic properties were summarized, with the change of volumetric water content and the applied shear stress and based on the experimental results, the law of emulsion is explained from the micro level. It is proposed that brittle fracture exists between wax crystals, and flexible fracture was found in the interaction between water droplets and wax crystals.展开更多
Based on statistical analysis on the situation of casing damage and water injection pressure in Pubei Oilfield, it shows that the main forms of casing damage in Pubei Oilfield are deformation and dislocation. Dip angl...Based on statistical analysis on the situation of casing damage and water injection pressure in Pubei Oilfield, it shows that the main forms of casing damage in Pubei Oilfield are deformation and dislocation. Dip angle and faults have a significant impact on casing damage and casing damage is closely related to water injection pressure. Through laboratory simulating experiment and theoretical calculation, the formula of critical injection pressure giving rise to casing damage is obtained and the preventive measures are drafted.展开更多
Thixotropic properties are one of the low temperature rheology behaviors of gelled waxy crudes. In order to study the thixotropic behavior of gelled waxy crudes oil under cyclic loading of linear increasing and decrea...Thixotropic properties are one of the low temperature rheology behaviors of gelled waxy crudes. In order to study the thixotropic behavior of gelled waxy crudes oil under cyclic loading of linear increasing and decreasing of shear rate, three different types of waxy crude oil were studied ex-perimentally by using MARSIII rheometer. It is found that hysteresis loop area could represent strength of thixotropic properties under that loading. With increasing of the rate of share rate sweep, the area of second hysteresis loop is much smaller than first one and began a slow decline from the third hysteresis loop. Areas of each hysteresis loops were decreased with increasing temperature, but it was different in decline rate—the lower the temperature, the greater the rate of decline. The maximum rate of decrease is the first hysteresis loop with exponential decline, and remaining hysteresis hoops approximately decrease linearly. In addition, based on the experi-mental results an empirical correlation is developed to describe the relationship of hysteresis loop area and rate of share rate sweep.展开更多
Thixotropy is a great rheological behavior of waxy crudes oils and is of great importance for hydraulic characteristics and security of oil pipeline restart. In this paper, through the experiment of four waxy crudes, ...Thixotropy is a great rheological behavior of waxy crudes oils and is of great importance for hydraulic characteristics and security of oil pipeline restart. In this paper, through the experiment of four waxy crudes, three kinds of thixotropic rheology characteristics in the conditions that shear stress decays under a constant shear rate, shear stress decays after shear rate steps up and hysteresis loop of shear rate cycle changes are studied . For eight thixotropic models, experimental data are fitted in the method of least-squares and average deviation is taken as a statistical indicator to evaluate the thixotropic models. It shows that the model with the idea of Cheng that completely reversible and totally irreversible structures both exist in waxy oil products and based on Houska model can describe thixotropic behaviors of waxy crudes most well.展开更多
At 14：28 hours （Beijing time） of May 12, 2008, a magnitude 8 earthquake jolted nearly half of Asia.Barely eight hours had passed before a regiment of the Chinese People＇s Liberation Army （PLA） left its base for ...At 14：28 hours （Beijing time） of May 12, 2008, a magnitude 8 earthquake jolted nearly half of Asia.Barely eight hours had passed before a regiment of the Chinese People＇s Liberation Army （PLA） left its base for the hardest-hit Sichuan Province to save lives. The No. 18 Artillery Regiment of the PLA 14th Army Group Corps arrived in Chengdu, the provincial capital, the following day. alighting from the at 18：00 hours of Immediately after train, officers and soldiers of the regiment were ordered to head for Mianzhu County just a few dozen kilometers from Wenchuan County, the epicenter, where up to 80% of the buildings had collapsed.展开更多
This paper investigates the state-tracking control problem in conversion mode of a tilt-rotor aircraft with a switching modeling method and a smooth interpolation technique.Based on the nonlinear model of the conversi...This paper investigates the state-tracking control problem in conversion mode of a tilt-rotor aircraft with a switching modeling method and a smooth interpolation technique.Based on the nonlinear model of the conversion mode,a switched linear model is developed by using the Jacobian linearization method and designing the switching signal based on the mast angle.Furthermore,an ℋ_(∞) state-tracking control scheme is designed to deal with the conversion mode control issue.Moreover,instead of limiting the amplitude of control inputs,a smooth interpolation method is developed to create bumpless performance.Finally,the XV-15 tilt-rotor aircraft is chosen as a prototype to illustrate the effectiveness of this developed control method.展开更多
FAM 19A4 is an abbreviation for family with sequence similarity 19 （chemokine （C-C motif）-Iike） member A4, which is a secretory protein expressed in low levels in normal tissues. The biological functions of FAM19A...FAM 19A4 is an abbreviation for family with sequence similarity 19 （chemokine （C-C motif）-Iike） member A4, which is a secretory protein expressed in low levels in normal tissues. The biological functions of FAM19A4 remain to be determined, and its potential receptor（s） is unclarified. In this study, we demonstrated that FAM 19A4 was a classical secretory protein and we verified for the first time that its mature protein is composed of 95 amino acids. We found that the expression of this novel cytokine was upregulated in lipopolysaccharide （LPS）-stimulated monocytes and macrophages and was typically in polarized M 1. FAM 19A4 shows chemotactic activities on macrophages and enhances the macrophage phagocytosis of zymosan both in vitro and in vivo with noticeable increases of the phosphorylation of protein kinase B （Akt）. FAM 19A4 can also increase the release of reactive oxygen species （ROS） upon zymosan stimulation. Furthermore, based on receptor internalization, radio ligand binding assays and receptor blockage, we demonstrated for the first time that FAM19A4 is a novel ligand of formyl peptide receptor 1 （FPR1）. The above data indicate that upon inflammatory stimulation, monocyte/macrophage-derived FAM 19A4 may play a crucial role in the migration and activation of macrophages during pathogenic infections.展开更多
Cytokines are small proteins secreted by a variety of cells,which regulate not only cell growth and differentiation but also immune function by binding to their corresponding receptors.1 Cytokines mainly include inter...Cytokines are small proteins secreted by a variety of cells,which regulate not only cell growth and differentiation but also immune function by binding to their corresponding receptors.1 Cytokines mainly include interleukin,colonystimulating factor(CSF),interferon,tumor necrosis factor,growth factor(GF)and chemokine.Chemokines are a class of cytokines with chemotactic activity and function by binding to G proteincoupled receptors.2 Chemokines and their receptors have important roles in inflammation and tumors by regulating chemotaxis,immunoregulation and the behavior of various cells.展开更多
The processing method applied to the side surface is different from the method applied to the light pass surface in neodymium phosphate glass(Nd:glass), and thus subsurface defects remain after processing. The subsurf...The processing method applied to the side surface is different from the method applied to the light pass surface in neodymium phosphate glass(Nd:glass), and thus subsurface defects remain after processing. The subsurface defects in the side surface influence the gain uniformity of Nd:glass, which is a key factor to evaluate the performance of amplifiers. The scattering characteristics of side subsurface defects were simulated by finite difference time domain(FDTD) Solutions software. The scattering powers of the glass fabricated by a computer numerical control(CNC)machine without cladding were tested at different incident angles. The trend of the curve was similar to the simulated result, while the smallest point was different with the complex true morphology. The simulation showed that the equivalent residual reflectivity of the cladding glass can be more than 0.1% when the number of defects in a single gridding is greater than 50.展开更多
文摘Emulsion of waxy crude oil is one of the common states in the subsea pipeline. At low temperatures in offshore environment, waxy crude oils with water could form the crude oil emulsion gel of oil-in-water emulsion. Thus, the waxy crude oil emulsion viscoelastic behavior for deep sea transportation and restarting pipeline safety is particularly important. By means of MASIII HAAKE rheometer which is produced by German company, waxy crude oil emulsion viscoelastic behavior is explored at different volumetric water contents and different shear stresses. By analyzing the rate of change of shear rate in the initial stage, the influence rules of viscoelastic properties were summarized, with the change of volumetric water content and the applied shear stress and based on the experimental results, the law of emulsion is explained from the micro level. It is proposed that brittle fracture exists between wax crystals, and flexible fracture was found in the interaction between water droplets and wax crystals.
文摘Based on statistical analysis on the situation of casing damage and water injection pressure in Pubei Oilfield, it shows that the main forms of casing damage in Pubei Oilfield are deformation and dislocation. Dip angle and faults have a significant impact on casing damage and casing damage is closely related to water injection pressure. Through laboratory simulating experiment and theoretical calculation, the formula of critical injection pressure giving rise to casing damage is obtained and the preventive measures are drafted.
文摘Thixotropic properties are one of the low temperature rheology behaviors of gelled waxy crudes. In order to study the thixotropic behavior of gelled waxy crudes oil under cyclic loading of linear increasing and decreasing of shear rate, three different types of waxy crude oil were studied ex-perimentally by using MARSIII rheometer. It is found that hysteresis loop area could represent strength of thixotropic properties under that loading. With increasing of the rate of share rate sweep, the area of second hysteresis loop is much smaller than first one and began a slow decline from the third hysteresis loop. Areas of each hysteresis loops were decreased with increasing temperature, but it was different in decline rate—the lower the temperature, the greater the rate of decline. The maximum rate of decrease is the first hysteresis loop with exponential decline, and remaining hysteresis hoops approximately decrease linearly. In addition, based on the experi-mental results an empirical correlation is developed to describe the relationship of hysteresis loop area and rate of share rate sweep.
文摘Thixotropy is a great rheological behavior of waxy crudes oils and is of great importance for hydraulic characteristics and security of oil pipeline restart. In this paper, through the experiment of four waxy crudes, three kinds of thixotropic rheology characteristics in the conditions that shear stress decays under a constant shear rate, shear stress decays after shear rate steps up and hysteresis loop of shear rate cycle changes are studied . For eight thixotropic models, experimental data are fitted in the method of least-squares and average deviation is taken as a statistical indicator to evaluate the thixotropic models. It shows that the model with the idea of Cheng that completely reversible and totally irreversible structures both exist in waxy oil products and based on Houska model can describe thixotropic behaviors of waxy crudes most well.
文摘At 14：28 hours （Beijing time） of May 12, 2008, a magnitude 8 earthquake jolted nearly half of Asia.Barely eight hours had passed before a regiment of the Chinese People＇s Liberation Army （PLA） left its base for the hardest-hit Sichuan Province to save lives. The No. 18 Artillery Regiment of the PLA 14th Army Group Corps arrived in Chengdu, the provincial capital, the following day. alighting from the at 18：00 hours of Immediately after train, officers and soldiers of the regiment were ordered to head for Mianzhu County just a few dozen kilometers from Wenchuan County, the epicenter, where up to 80% of the buildings had collapsed.
基金Project supported by the National Natural Science Foundation of China (Nos.62103186 and 62122038)the Natural Science Foundation of Jiangsu Province,China (Nos.BK20210285 and BK20211565)the China Postdoctoral Science Foundation (Nos.2021TQ0151 and 2021M691571)。
文摘This paper investigates the state-tracking control problem in conversion mode of a tilt-rotor aircraft with a switching modeling method and a smooth interpolation technique.Based on the nonlinear model of the conversion mode,a switched linear model is developed by using the Jacobian linearization method and designing the switching signal based on the mast angle.Furthermore,an ℋ_(∞) state-tracking control scheme is designed to deal with the conversion mode control issue.Moreover,instead of limiting the amplitude of control inputs,a smooth interpolation method is developed to create bumpless performance.Finally,the XV-15 tilt-rotor aircraft is chosen as a prototype to illustrate the effectiveness of this developed control method.
文摘FAM 19A4 is an abbreviation for family with sequence similarity 19 （chemokine （C-C motif）-Iike） member A4, which is a secretory protein expressed in low levels in normal tissues. The biological functions of FAM19A4 remain to be determined, and its potential receptor（s） is unclarified. In this study, we demonstrated that FAM 19A4 was a classical secretory protein and we verified for the first time that its mature protein is composed of 95 amino acids. We found that the expression of this novel cytokine was upregulated in lipopolysaccharide （LPS）-stimulated monocytes and macrophages and was typically in polarized M 1. FAM 19A4 shows chemotactic activities on macrophages and enhances the macrophage phagocytosis of zymosan both in vitro and in vivo with noticeable increases of the phosphorylation of protein kinase B （Akt）. FAM 19A4 can also increase the release of reactive oxygen species （ROS） upon zymosan stimulation. Furthermore, based on receptor internalization, radio ligand binding assays and receptor blockage, we demonstrated for the first time that FAM19A4 is a novel ligand of formyl peptide receptor 1 （FPR1）. The above data indicate that upon inflammatory stimulation, monocyte/macrophage-derived FAM 19A4 may play a crucial role in the migration and activation of macrophages during pathogenic infections.
基金The work is supported by grant from the National Natural Science Foundation of China(81273233).
文摘Cytokines are small proteins secreted by a variety of cells,which regulate not only cell growth and differentiation but also immune function by binding to their corresponding receptors.1 Cytokines mainly include interleukin,colonystimulating factor(CSF),interferon,tumor necrosis factor,growth factor(GF)and chemokine.Chemokines are a class of cytokines with chemotactic activity and function by binding to G proteincoupled receptors.2 Chemokines and their receptors have important roles in inflammation and tumors by regulating chemotaxis,immunoregulation and the behavior of various cells.
基金supported by National Natural Science Foundation of China (No.61205212)
文摘The processing method applied to the side surface is different from the method applied to the light pass surface in neodymium phosphate glass(Nd:glass), and thus subsurface defects remain after processing. The subsurface defects in the side surface influence the gain uniformity of Nd:glass, which is a key factor to evaluate the performance of amplifiers. The scattering characteristics of side subsurface defects were simulated by finite difference time domain(FDTD) Solutions software. The scattering powers of the glass fabricated by a computer numerical control(CNC)machine without cladding were tested at different incident angles. The trend of the curve was similar to the simulated result, while the smallest point was different with the complex true morphology. The simulation showed that the equivalent residual reflectivity of the cladding glass can be more than 0.1% when the number of defects in a single gridding is greater than 50.
