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Electric Power Generation: Ocean Thermal Energy Conversion
Published in William C. Dickinson, Paul N. Cheremisinoff, Solar Energy Technology Handbook, 2018
Station keeping of OTEC platforms will be required, both for platforms connected to shore via submarine umbilicals (such as electrical cables) and for platforms producing energy-intensive products on board (i.e., OTEC plant ships). However, the stationkeeping requirements in the former case will be more stringent. Station keeping can be achieved through dynamic positioning and/or by mooring. Dynamic positioning refers to the utilization of effluent thrust, thrusters, or a combination of both [38]. However, use of solely sea-water effluents to achieve this thrust would probably require additional pumping power during some sea conditions, compared to the power required purely to discharge effluents for plant operation. Also, this extra pumping power could constitute a prohibitive power/cost factor for overall plant sizes in the tens of megawatts (but not hundreds of megawatts) if sea conditions at the plant site are severe. Mooring costs in a representative severe plant environment also exhibit an economy of scale, decreasing by approximately an order of magnitude for plant net power outputs in the range of 20 to 1000 MWe[38].
Offshore Structure and Design
Published in Shashi Shekhar Prasad Singh, Jatin R. Agarwal, Nag Mani, Offshore Operations and Engineering, 2019
Shashi Shekhar Prasad Singh, Jatin R. Agarwal, Nag Mani
Ships or vessels at sea have to be kept in their place to enable oil or gas production, transfer, and storage on board. Mooring is a system of permanent or temporary station keeping at sea. A vessel is said to be moored when it is fastened or held secured to a fixed object such as a pier or quay or to a floating object such as an anchor buoy using cables, anchors, or lines. Mooring and anchors are very critical for the stability of a floating system (Figure 2.17).
Distributed optimal formation algorithm for multi-satellites system with time-varying performance function
Published in International Journal of Control, 2020
There are a lot of works have been produced considering the problem of the formation between two or more satellites. Vandyke and Hall (2006), Jin, Jiang, and Sun (2008) and Zou and Kumar (2012) addressed the satellite formation flying problem by considering the attitude coordination control problem. Zhou, Hu, and Friswell (2013) and Zhou, Xia, Wang, and Fu (2015) have studied the finite-time attitude synchronisation. Chung et al. (2016) considered attitude synchronisation of a group of satellites, and performed the stability of the proposed tracking control law by utilising the contraction analysis. Scharf, Hadaegh, and Ploen (2003), Kristiansen and Nicklasson (2009) and Haghighi and Khiang Pang (2016) proposed the formation strategy by using the relative motion control. Hui and Li (2009) considered the satellite formation flying problem using the terminal sliding mode control. Lim and Bang (2009) developed an adaptive control approach which was combined with a backstepping technique for the relative position tracking problem of satellites. Haghighi and Pang (2017) addressed the formation flying problem of underactuated nanosatellites by concurrent attitude-position control. And Varma and Kumar (2015) considered the problem of the reconfiguration of the formation. Some interesting results may be found in Bevilacqua and Romano (2008) and Bevilacqua, Hall, and Romano (2009), where the effect is taken into account. As for very low Earth orbits, the lift force should be considered as well (Horsley, Nikolaev, & Pertica, 2013). In Circi (2015), the solar radiation pressure has been considered for station-keeping problems. Some reconfiguration manoeuvres have been presented in Shahid and Kumar (2014) and Hou, Zhang, Zhao, and Sun (2016). Finally, an interesting application of the geomagnetic Lorentz force for formation reconfiguration manoeuvres has been proposed in Huang, Yan, and Zhou (2014).