During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure ...During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m.It is found that severe slugging can be divided into three severe slugging regimes：regime I at low gas and liquid flow rates with large pressure fluctuation,intermittent flow of liquid and gas in the riser,and apparent cutoff of liquid phase,regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff,regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow.The results indicate that severe slugging still occurs when the declination angle of pipeline is 0,and there are mainly two kinds of regimes：regime I and regime II.As the angle increases,the formation ranges of regime I and regime III increase slightly while that of regime II is not affected.With the increase of gas superficial velocity and liquid superficial velocity,the pressure fluctuation at the bottom of riser increases initially and then decreases.The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.展开更多
Carbon fiber reinforced plastics provide many excellent properties and are widely used in the aerospace industry.However,the existing composites autoclave process still faces difficulties such as high-energy consumpti...Carbon fiber reinforced plastics provide many excellent properties and are widely used in the aerospace industry.However,the existing composites autoclave process still faces difficulties such as high-energy consumption,uneven distribution of temperature field,complications of pressure transmission,and high cost,which limit their application in manufacturing of large complex composites components.In this study,the vibration treatment was introduced into the composites microwave curing process innovatively.On the basis of giving full play to the uniform heating characteristics of the microwave,the problems of a large number of internal defects and poor molding quality caused by the insufficient curing pressure have been solved.The results showed that the samples cured by the improved microwave process without external pressure had a few internal voids,excellent interface bonding conditions,and lower residual stress.Their properties were almost consistent with the samples prepared by the standard autoclave process,which provided a new method for the high-performance,efficient,safe,and low-cost manufacturing of large complex composites components.展开更多
UV wavelength auto-tuned tuned output system is realized by the difference method. Controlled by the microprocessor, output wavelength auto- tracking is achieved.Besides, equipment self-checking auto-positioning and t...UV wavelength auto-tuned tuned output system is realized by the difference method. Controlled by the microprocessor, output wavelength auto- tracking is achieved.Besides, equipment self-checking auto-positioning and temperature correct are realized,The wavelength tuned output efficiency in the experiment is better than 97 %.展开更多
In recent years, the popular multifractal detrended fluctuation analysis （MF-DFA） is extended to two-dimensional （2D） version, which has been applied in some field of image processing. In this paper, based on the ...In recent years, the popular multifractal detrended fluctuation analysis （MF-DFA） is extended to two-dimensional （2D） version, which has been applied in some field of image processing. In this paper, based on the 2D MF-DFA, a novel multifractal estimation method for images, which we called the local multifractal detrended fluctuation analysis （LMF-DFA）, is proposed to recognize and distinguish 20 types of tea breeds. A set of new multifractal descriptors, namely the local multifractal fluctuation exponents is defined to portray the local scaling properties of a surface. After collecting 10 tea leaves for each breed and photographing them to standard images, the LMF-DFA method is used to extract characteristic parameters for the images. Our analysis finds that there are significant differences among the different tea breeds＇ characteristic parameters by analysis of variance. Both the proposed LMF-DFA exponents and another classic parameter, namely the exponent based on capacity measure method have been used as features to distinguish the 20 tea breeds. The comparison results illustrate that the LMF-DFA estimation can differentiate the tea breeds more effectively and provide more satisfactory accuracy.展开更多
基金Supported by the National High Technology Research and Development Program of China(2006AA09Z302)
文摘During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m.It is found that severe slugging can be divided into three severe slugging regimes：regime I at low gas and liquid flow rates with large pressure fluctuation,intermittent flow of liquid and gas in the riser,and apparent cutoff of liquid phase,regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff,regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow.The results indicate that severe slugging still occurs when the declination angle of pipeline is 0,and there are mainly two kinds of regimes：regime I and regime II.As the angle increases,the formation ranges of regime I and regime III increase slightly while that of regime II is not affected.With the increase of gas superficial velocity and liquid superficial velocity,the pressure fluctuation at the bottom of riser increases initially and then decreases.The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.
基金Project(2018YFA0702800)supported by the National Key R&D Program of China。
文摘Carbon fiber reinforced plastics provide many excellent properties and are widely used in the aerospace industry.However,the existing composites autoclave process still faces difficulties such as high-energy consumption,uneven distribution of temperature field,complications of pressure transmission,and high cost,which limit their application in manufacturing of large complex composites components.In this study,the vibration treatment was introduced into the composites microwave curing process innovatively.On the basis of giving full play to the uniform heating characteristics of the microwave,the problems of a large number of internal defects and poor molding quality caused by the insufficient curing pressure have been solved.The results showed that the samples cured by the improved microwave process without external pressure had a few internal voids,excellent interface bonding conditions,and lower residual stress.Their properties were almost consistent with the samples prepared by the standard autoclave process,which provided a new method for the high-performance,efficient,safe,and low-cost manufacturing of large complex composites components.
文摘UV wavelength auto-tuned tuned output system is realized by the difference method. Controlled by the microprocessor, output wavelength auto- tracking is achieved.Besides, equipment self-checking auto-positioning and temperature correct are realized,The wavelength tuned output efficiency in the experiment is better than 97 %.
文摘In recent years, the popular multifractal detrended fluctuation analysis （MF-DFA） is extended to two-dimensional （2D） version, which has been applied in some field of image processing. In this paper, based on the 2D MF-DFA, a novel multifractal estimation method for images, which we called the local multifractal detrended fluctuation analysis （LMF-DFA）, is proposed to recognize and distinguish 20 types of tea breeds. A set of new multifractal descriptors, namely the local multifractal fluctuation exponents is defined to portray the local scaling properties of a surface. After collecting 10 tea leaves for each breed and photographing them to standard images, the LMF-DFA method is used to extract characteristic parameters for the images. Our analysis finds that there are significant differences among the different tea breeds＇ characteristic parameters by analysis of variance. Both the proposed LMF-DFA exponents and another classic parameter, namely the exponent based on capacity measure method have been used as features to distinguish the 20 tea breeds. The comparison results illustrate that the LMF-DFA estimation can differentiate the tea breeds more effectively and provide more satisfactory accuracy.
