The purpose of using life extending control for Black Hawk UH-60 helicopter is to make a trade-off between the handling qualities and the service life of critical components. An increase in service life span results in enhanced safety and the reduction in maintenance costs. This paper presents a design methodology of life extending control for structural durability and high performance of mechanical system, which is based on an explicit dynamic inversion control scheme. A real-time nonlinear fatigue crack growth model is built to predict fatigue damage resulting from the impact of cyclic bending stress on rotor shaft, which serves as an indicator of service life. The 4-axis gainscheduled flight controller, whose gains are adjusted as a function of damage and flight velocity, is designed to regulate roll attitude, pitch attitude, vertical velocity and yaw rate. The nonlinear system simulation results show that the responses can meet the requirements on ADS-33 Level 1 handling qualities and that the 4-axis decoupling control is realized. As the damage increases, the tracking performance is slightly degraded, which results in smaller transients in bending moment response.
根据云计算数据中心网络(data center networks,DCNS)架构的特点,从网络架构的角度对低速率拒绝服务(low-rate denial of service,LDo S)攻击进行建模。提出基于可用带宽欧氏距离的LDo S攻击检测方法,其本质是依据LDo S攻击导致同一路由域内所有链路可用带宽同时增大的特征,将可用带宽的平均欧氏距离作为LDo S攻击检测测度。改进了传统的探测间隔模型(probe gap model,PGM),并将其专门用于云计算环境下的可用带宽测量。在实际的网络环境中对LDo S攻击效果和LDo S检测性能进行测试,结果表明:1)DCNS内的LDo S攻击比洪水式拒绝服务(flooding denial of service,FDo S)攻击更具危害;2)所提出的检测方法能够准确检测LDo S攻击,检测率达到98%。
