The progressive and mixing algorithm(PAMA) is a method for surface modeling and editing,which is developed for effective and flexible applications in many environments,such as computer-aided design(CAD) and computer-a...The progressive and mixing algorithm(PAMA) is a method for surface modeling and editing,which is developed for effective and flexible applications in many environments,such as computer-aided design(CAD) and computer-aided geometric design(CAGD).In this paper,the construction scheme and continuities of PAMA are discussed,which provide a mathematics analysis of PAMA.The analysis and results show that the PAMA provides a new method of surface modeling and editing with four more degrees of freedom for designers to manipulate a 3D object.展开更多
Polyalkylmethacrylates(PAMAs) are well-known as viscosity index improvers and dispersant boosters.This paper shows that PAMAs are able to adsorb from oil solution on to metal surfaces,to produce thick,viscous boundary...Polyalkylmethacrylates(PAMAs) are well-known as viscosity index improvers and dispersant boosters.This paper shows that PAMAs are able to adsorb from oil solution on to metal surfaces,to produce thick,viscous boundary films.These films enhance lubricant film formation in slow speed and high temperature conditions and thus produce a significant reduction of friction.A systematic study of this phenomenon has made use of the highly flexible nature of PAMA chemistry.A range of dispersant and non-dispersant polymethacrylates has been synthesized.The influence of different functionalities,molecular weights and architectures on both boundary film formation and friction has been explored using optical interferometry and friction-speed charting.From the results, guidelines have been developed for designing PAMAs having optimal boundary lubricating properties.Through their ability to form boundary films PAMAs can significantly contribute to reduce wear in engine,gear and hydraulic lubrication.As a consequence of their viscometric and tribological performance PAMAs can furthermore improve fuel and energy efficiency in different,namely engine and hydraulic applications.Extensive work is currently conducted in the lubricant industry to develop engine oils with lower sulfur,phosphorus and metal content(low SAPS) and to optimize their frictional properties through the use of friction modifiers or synthetic base stocks.We have investigated the contribution of PAMA viscosity index improvers and boosters to improve fuel economy and to reduce wear levels.This paper reports our efforts to develop a new range of PAMAs that have been optimized in terms of composition,architecture,molecular weight and functionality and which can be used in low viscosity,low SAPS formulations to help meet the stringent requirements of modern engine oils.展开更多
When temperature of paraffinic mineral oil base stocks is decreased belowcloud point,waxy hydrocarbonscome out of solution and growinto plates and needles wax crystalsforming a three-di mensional networkthat totallyi ...When temperature of paraffinic mineral oil base stocks is decreased belowcloud point,waxy hydrocarbonscome out of solution and growinto plates and needles wax crystalsforming a three-di mensional networkthat totallyi m-mobilizes the oil.Addition of a properlyselected PPD will provide a verylarge enhancement of low-temperature perfor-mance of the oil at verylowconcentrations.Howtoselect a right PPDfor your formulations are discussedinthis paper.展开更多
Traditional calibration methods mostly focus on the calibration of detection systems while the calibration from the sampling and pre-condition systems to the detection system is usually ignored.In this regard,a Primar...Traditional calibration methods mostly focus on the calibration of detection systems while the calibration from the sampling and pre-condition systems to the detection system is usually ignored.In this regard,a Primary Standard Aerosol Mass Concentration Calibration System(PAMAS)is developed for the whole-process calibration of time-resolved aerosol measurement instruments.PAMAS is composed of a particle generation chamber,an ultrasonic atomizer,a dilution system,and a syringe pump.It is designed to steadily generate standard aerosol particles of known concentrations(≤250μg/m^(3)),chemical compositions,and stable particle size distributions.Monodispersed aerosol can be generated in the size range of hundreds of nanometers to several micrometers with a narrow size distribution.The generated particles with different compositions generated by PAMAS have been well verified by the filter-based gravimetric method,yielding accuracy and R^(2) of more than 95%and 0.999 in a wide concentration range.The response time by changing the target concentration of reference particles is 1-2 min.PAMAS has been applied to various types of time-resolved aerosol measurement instruments,including particle mass concentration monitors(Beta Attenuation and Tapered Element Oscillating Microbalance),online Ion Chromatograph,and semi-continuous OCEC carbon aerosol analyzer.Very consistent results between PAMAS and calibrated instruments can be obtained if the instruments are functioning well.As for instruments with certain technical issues,PAMAS can serve as a good tool for performance evaluation and quality assurance of the instruments and the accuracy of the measurement data can be adjusted based on the calibration results.展开更多
基金the 2009 Excellent Going Abroad Experts Training Program in Hebei Province,China(No.[2010]76)
文摘The progressive and mixing algorithm(PAMA) is a method for surface modeling and editing,which is developed for effective and flexible applications in many environments,such as computer-aided design(CAD) and computer-aided geometric design(CAGD).In this paper,the construction scheme and continuities of PAMA are discussed,which provide a mathematics analysis of PAMA.The analysis and results show that the PAMA provides a new method of surface modeling and editing with four more degrees of freedom for designers to manipulate a 3D object.
文摘Polyalkylmethacrylates(PAMAs) are well-known as viscosity index improvers and dispersant boosters.This paper shows that PAMAs are able to adsorb from oil solution on to metal surfaces,to produce thick,viscous boundary films.These films enhance lubricant film formation in slow speed and high temperature conditions and thus produce a significant reduction of friction.A systematic study of this phenomenon has made use of the highly flexible nature of PAMA chemistry.A range of dispersant and non-dispersant polymethacrylates has been synthesized.The influence of different functionalities,molecular weights and architectures on both boundary film formation and friction has been explored using optical interferometry and friction-speed charting.From the results, guidelines have been developed for designing PAMAs having optimal boundary lubricating properties.Through their ability to form boundary films PAMAs can significantly contribute to reduce wear in engine,gear and hydraulic lubrication.As a consequence of their viscometric and tribological performance PAMAs can furthermore improve fuel and energy efficiency in different,namely engine and hydraulic applications.Extensive work is currently conducted in the lubricant industry to develop engine oils with lower sulfur,phosphorus and metal content(low SAPS) and to optimize their frictional properties through the use of friction modifiers or synthetic base stocks.We have investigated the contribution of PAMA viscosity index improvers and boosters to improve fuel economy and to reduce wear levels.This paper reports our efforts to develop a new range of PAMAs that have been optimized in terms of composition,architecture,molecular weight and functionality and which can be used in low viscosity,low SAPS formulations to help meet the stringent requirements of modern engine oils.
文摘When temperature of paraffinic mineral oil base stocks is decreased belowcloud point,waxy hydrocarbonscome out of solution and growinto plates and needles wax crystalsforming a three-di mensional networkthat totallyi m-mobilizes the oil.Addition of a properlyselected PPD will provide a verylarge enhancement of low-temperature perfor-mance of the oil at verylowconcentrations.Howtoselect a right PPDfor your formulations are discussedinthis paper.
基金supported by the National Natural Science Foundation of China (grant No.42175119).
文摘Traditional calibration methods mostly focus on the calibration of detection systems while the calibration from the sampling and pre-condition systems to the detection system is usually ignored.In this regard,a Primary Standard Aerosol Mass Concentration Calibration System(PAMAS)is developed for the whole-process calibration of time-resolved aerosol measurement instruments.PAMAS is composed of a particle generation chamber,an ultrasonic atomizer,a dilution system,and a syringe pump.It is designed to steadily generate standard aerosol particles of known concentrations(≤250μg/m^(3)),chemical compositions,and stable particle size distributions.Monodispersed aerosol can be generated in the size range of hundreds of nanometers to several micrometers with a narrow size distribution.The generated particles with different compositions generated by PAMAS have been well verified by the filter-based gravimetric method,yielding accuracy and R^(2) of more than 95%and 0.999 in a wide concentration range.The response time by changing the target concentration of reference particles is 1-2 min.PAMAS has been applied to various types of time-resolved aerosol measurement instruments,including particle mass concentration monitors(Beta Attenuation and Tapered Element Oscillating Microbalance),online Ion Chromatograph,and semi-continuous OCEC carbon aerosol analyzer.Very consistent results between PAMAS and calibrated instruments can be obtained if the instruments are functioning well.As for instruments with certain technical issues,PAMAS can serve as a good tool for performance evaluation and quality assurance of the instruments and the accuracy of the measurement data can be adjusted based on the calibration results.
