When using topside choking to eliminate severe slugging in offshore pipeline-riser systems,the resulting stability and effectiveness depend critically on the choice of variables in the associated control model.In this...When using topside choking to eliminate severe slugging in offshore pipeline-riser systems,the resulting stability and effectiveness depend critically on the choice of variables in the associated control model.In this study,both potential process variables and manipulated variables are investigated via manual choking experiments.Monotonicity and linearity are adopted as principles for selecting the optimal variables,and the availability of signals in an offshore field is also considered.Both amplitude-domain and time-domain variables are studied,of which five are recommended as the process variable,while the resistance factor of the choking valve is the optimal manipulated variable;other variables may act as auxiliary variables in the control model.How to determine the set value of the process variable is also discussed.Validation experiments with automatic control show that the optimized variables enable faster stabilization.This study offers a reference for the design of slugging control for offshore fields.展开更多
This paper presented an automatic gain control （AGC） circuit suitable for FM/cw ladar. The proposed architecture was based on two-stage variable gain amplifier （VGA） chain with a novel DC offset canceller circuit,...This paper presented an automatic gain control （AGC） circuit suitable for FM/cw ladar. The proposed architecture was based on two-stage variable gain amplifier （VGA） chain with a novel DC offset canceller circuit, which contained an improved Gilbert cell and a Gm-C feedback loop. To keep the VGA with a linearity in dB characteristic, an improved exponential gain control circuit was introduced. The AGC was implemented in 0.18 gm standard CMOS process. Simulation and measurement results verified that its gain ranged from -20 dB to 30 dB, and band- width ranged from 100 kHz to 10 MHz. Its power consumption was 19.8 mW under a voltage supply of 3.3 V.展开更多
Several key problems in the research and development of continuously variable transmission for automobile, such as those connected to the transmitting frictional pair and the related automatic tight pressing actuator...Several key problems in the research and development of continuously variable transmission for automobile, such as those connected to the transmitting frictional pair and the related automatic tight pressing actuator, the transmission ratio control logic and the related automatic control system, are discussed. The strategies taken for solving these key problems are described.展开更多
基金the financial support received from the China National Key Research and Development Project(Grant No.2022YFC2806202)the Fundamental Research Funds for the Central Universities(Grant No.xtr042024002).
文摘When using topside choking to eliminate severe slugging in offshore pipeline-riser systems,the resulting stability and effectiveness depend critically on the choice of variables in the associated control model.In this study,both potential process variables and manipulated variables are investigated via manual choking experiments.Monotonicity and linearity are adopted as principles for selecting the optimal variables,and the availability of signals in an offshore field is also considered.Both amplitude-domain and time-domain variables are studied,of which five are recommended as the process variable,while the resistance factor of the choking valve is the optimal manipulated variable;other variables may act as auxiliary variables in the control model.How to determine the set value of the process variable is also discussed.Validation experiments with automatic control show that the optimized variables enable faster stabilization.This study offers a reference for the design of slugging control for offshore fields.
基金Supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2012ZX03004008)
文摘This paper presented an automatic gain control （AGC） circuit suitable for FM/cw ladar. The proposed architecture was based on two-stage variable gain amplifier （VGA） chain with a novel DC offset canceller circuit, which contained an improved Gilbert cell and a Gm-C feedback loop. To keep the VGA with a linearity in dB characteristic, an improved exponential gain control circuit was introduced. The AGC was implemented in 0.18 gm standard CMOS process. Simulation and measurement results verified that its gain ranged from -20 dB to 30 dB, and band- width ranged from 100 kHz to 10 MHz. Its power consumption was 19.8 mW under a voltage supply of 3.3 V.
文摘Several key problems in the research and development of continuously variable transmission for automobile, such as those connected to the transmitting frictional pair and the related automatic tight pressing actuator, the transmission ratio control logic and the related automatic control system, are discussed. The strategies taken for solving these key problems are described.
