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
由2篇论文组成的系列论文旨在研究广域闭环控制系统(wide-area closed-loop control system,WACS)中时延的特性。在系列论文第1篇的研究基础上,首先提出估计实际WACS中闭环时延的方法,综合考虑通信时延与操作时延,提出正态分布模型以估...由2篇论文组成的系列论文旨在研究广域闭环控制系统(wide-area closed-loop control system,WACS)中时延的特性。在系列论文第1篇的研究基础上,首先提出估计实际WACS中闭环时延的方法,综合考虑通信时延与操作时延,提出正态分布模型以估计实际系统中的闭环时延分布,并给出确定正态分布模型参数的方法。然后介绍在实际WACS中实测闭环时延的时标对比法。最后,在专用通道与非专用通道的条件下,实测贵州电网WACS中的闭环时延,并将实测结果与使用正态分布模型的估计结果进行对比分析,验证了所提出的正态分布估计模型。该文对时延的分析及测试结果对广域闭环控制的研究及应用具有参考价值。展开更多
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.
文摘由2篇论文组成的系列论文旨在研究广域闭环控制系统(wide-area closed-loop control system,WACS)中时延的特性。在系列论文第1篇的研究基础上,首先提出估计实际WACS中闭环时延的方法,综合考虑通信时延与操作时延,提出正态分布模型以估计实际系统中的闭环时延分布,并给出确定正态分布模型参数的方法。然后介绍在实际WACS中实测闭环时延的时标对比法。最后,在专用通道与非专用通道的条件下,实测贵州电网WACS中的闭环时延,并将实测结果与使用正态分布模型的估计结果进行对比分析,验证了所提出的正态分布估计模型。该文对时延的分析及测试结果对广域闭环控制的研究及应用具有参考价值。
