Modeling of active heave compensation system of deep-sea mining based on dynamic vibration absorber and its H∞ robust control
The heave compensation system is vital for the deep-sea mining system undergoes excessive vibrations due to irregular wave loads for both normal operating and extreme conditions. To ensure its safety and operation efficiency, a novel active heave compensation system of deep-sea mining based on dynamic vibration absorber was proposed in this paper. The three-degree-of-freedom dynamic models of active heave compensation system based on dynamic vibration absorber in irregular wave are established. A H∞ Robust controller is designed for active heave compensation system by applying robust loop shaping control. The performance of H∞ robust controller and its robustness stability of the system are simulated and analyzed in frequency domain. The results show that the performance of the system in wave energy concentrated frequency domain of China's deep-sea mining field was improved by the concentrated weighting of acceleration output. And it also shows that the designed H∞ controller is perfect in system robustness stability against some parameter fluctuations of the system model. Therefore the designed active heave compensation system is practical to isolate the lift pipe and its support platform from the significant vibration of the ship motion induced by the irregular wave.
H2 active vibration control for offshore platform subjected to wave loading
Abstract Offshore platforms are usually located in hostile environments. These platforms undergo excessive vibrations due to wave loads for both normal operating and extreme conditions. To ensure safety, the displacements of the platforms need to be limited, whereas for the comfort of people who work at the structures, accelerations also need to be restricted. This article is devoted to developing a proper procedure on applying H2 control algorithm for controlling the lateral vibration of a jacket-type offshore platform by using an active mass damper. In comparison with earlier studies, a number of improvements in problem formulation, wave force filter design, and control algorithm implementation are made. The present paper also numerically demonstrated the effectiveness of H2 active control. As expected, it significantly outperforms the corresponding passive control that uses a tuned mass damper.
La inseguridad jurídica en normas de contratación estatal
It is established by different studies that the issue of government procurement has been marred by several factors, the test objective to publicize these factors, we take as starting point the constant conflict between the branches of government to try and organize this subject; will collect and analyze diverse regulatory and case material in order to achieve evidence and demonstrate the different concepts of constant change that produces excessive regulation of the subject procurement and is in turn causing rapid changes that result in legal uncertainty for our law on the Contract Status.