削坡减载在公路边坡稳定治理中应用

削坡减载是公路边坡稳定治理中常见的一种技术措施．本文主要是在对削坡减载概念做简要概述的前提下,详细的阐述了削坡减载在公路边坡稳定治理中的作用机理及优缺点．从多方面分析了削坡减载具体适宜情况、施工工艺及注意事项等。     

Robust buffer management mechanism in quality of service routers

Active queue management (AQM) is essentially a router buffer management strategy supporting TCP congestion control. Since existing AQM schemes exhibit poor performance and even instability in time delay uncertain networks, a robust buffer management (RBM) mechanism is proposed to guarantee the quality of service (QoS). RBM consists of a Smith predictor and two independent controllers. The Smith predictor is used to compensate for the round trip time (RTT) delay and to restrain its negative influence on network performance. The main feedback controller and the disturbance rejection controller are designed as proportional-integral (PI) controller and proportional (P) controller by internal model control (IMC) and frequency-domain analysis respectively. By simulation experiments in Netwrok-Simulator-2 (NS2), it is demonstrated that RBM can effectively manage the buffer occupation around the target value against time delay and system disturbance. Compared with delay compensation-AQM algorithm (DC-AQM), proportional-integral-derivative (PID) algorithm and random exponential marking (REM) algorithm, the RBM scheme exhibits the superiority in terms of stability, responsiveness and robustness.