This paper researches how to apply the advanced control technology of model predictive control （MPC） to the design of the dynamic positioning system （DPS） of a semi-submersible platform. First, a linear low-freque...This paper researches how to apply the advanced control technology of model predictive control （MPC） to the design of the dynamic positioning system （DPS） of a semi-submersible platform. First, a linear low-frequency motion model with three degrees of freedom was established in the context of a semi-submersible platform. Second, a model predictive controller was designed based on a model which took the constraints of the system into account. Third, simulation was carried out to demonstrate the feasibility of the controller. The results show that the model predictive controller has good performance and good at dealing with the constraints or the system.展开更多
A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force d...A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control(DSC) is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function(RBF) neural networks(NNs) can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers' wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN centers are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed control strategy.展开更多
This paper describes principles, methods and results of a large-scale （1： 25,000） structural-geodynamic mapping of Moscow territory. Neotectonic structures of different ranks--elevations and depressions, lineaments...This paper describes principles, methods and results of a large-scale （1： 25,000） structural-geodynamic mapping of Moscow territory. Neotectonic structures of different ranks--elevations and depressions, lineaments and GDAZ （geodynamic active zones） are presented on the map. Geodynamic active zones are linear or isometric crust volumes of different scales that localized spatially, where conditions for tectonic stress concentration and relaxation, and high gradients of movements and rocks deformity are favorable by different reasons. They differ from active faults, which are rare on geodynamic-stable platform territories, by absence of noticeable displacements in rocks and a more geodynamic stability. Nevertheless, GDAZ can be hazard to engineering buildings, since these zones are favorable for developing exogenous （such as erosion, impoundment, karst, sliding, etc.） and endogenous geological processes （such as seismicity, water-fluid permeability and heat flux）. They can also become migration and localization channels of nature-anthropogenic pollution.展开更多
基金Supported by the Basic Research Foundation of Central University(HEUCFZ1003)
文摘This paper researches how to apply the advanced control technology of model predictive control （MPC） to the design of the dynamic positioning system （DPS） of a semi-submersible platform. First, a linear low-frequency motion model with three degrees of freedom was established in the context of a semi-submersible platform. Second, a model predictive controller was designed based on a model which took the constraints of the system into account. Third, simulation was carried out to demonstrate the feasibility of the controller. The results show that the model predictive controller has good performance and good at dealing with the constraints or the system.
基金funded by the National Basic Research Program of China (Grant Nos. 2011CB013702 and 2011CB013703)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China (Grant No. 50921001)
文摘A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control(DSC) is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function(RBF) neural networks(NNs) can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers' wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN centers are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed control strategy.
文摘This paper describes principles, methods and results of a large-scale （1： 25,000） structural-geodynamic mapping of Moscow territory. Neotectonic structures of different ranks--elevations and depressions, lineaments and GDAZ （geodynamic active zones） are presented on the map. Geodynamic active zones are linear or isometric crust volumes of different scales that localized spatially, where conditions for tectonic stress concentration and relaxation, and high gradients of movements and rocks deformity are favorable by different reasons. They differ from active faults, which are rare on geodynamic-stable platform territories, by absence of noticeable displacements in rocks and a more geodynamic stability. Nevertheless, GDAZ can be hazard to engineering buildings, since these zones are favorable for developing exogenous （such as erosion, impoundment, karst, sliding, etc.） and endogenous geological processes （such as seismicity, water-fluid permeability and heat flux）. They can also become migration and localization channels of nature-anthropogenic pollution.
