基于改进网络模型的大时滞网络拥塞控制算法

　随着对网络拥塞控制的深入研究,出现了许多有关网络流量的控制理论及网络模型.Misra等人于2000年基于流体流(fluidflow)理论提出的模型被研究人员广为采用.但模型在推导过程中的一些近似却使得模型对网络行为描述不精确.本文对此从理论和实验结果两方面进行了详细分析,并对原模型进行了改进.基于改进的模型,把一种PID(ProportionalIntegralDifferential)及类PID设计方法用于AQM(ActiveQueueManagement)控制器的设计.对比仿真结果表明,该算法具有更好的性能.

Control mechanisms for gas hydrate production by depressurization in different scale hydrate reservoirs

The methane hydrate was formed in a pressure vessel 38 mm in id and 500 mm in length. Experimental works on gas production from the hydrate-bearing core by depressurization to 0.1, 0.93, and 1.93 MPa have been carried out. The hydrate reservoir simulator TOUGH-Fx/Hydrate was used to simulate the experimental gas production behavior, and the intrinsic hydration dissociation constant (K-0) fitted for the experimental data was on the order of 104 mol m(-2) Pa-1 s(-1), which was one order lower than that of the bulk hydrate dissociation. The sensitivity analyses based on the simulator have been carried out, and the results suggested that the hydrate dissociation kinetics had a great effect on the gas production behavior for the laboratory-scale hydrate-bearing core. However for a field-scale hydrate reservoir, the flow ability dominated the gas production behavior and the effect of hydrate dissociation kinetics on the gas production behavior could be neglected.