Browsing by Author "Liu, J."
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Integrated System Design for a Large Wind Turbine Supported on a Moored Semi-Submersible Platform(MDPI AG, 2018-10-22) Liu, J.; Thomas, E.; Manuel, L.; Griffith, D. Todd; Ruehl, K. M.; Barone, M.; Griffith, D. ToddOver the past few decades, wind energy has emerged as an alternative to conventional power generation that is economical, environmentally friendly and, importantly, renewable. Specifically, offshore wind energy is being considered by a number of countries to harness the stronger and more consistent wind resource compared to that over land. To meet the projected “20% energy from wind by 2030” scenario that was announced in 2006, 54 GW of added wind energy capacity need to come from offshore according to a National Renewable Energy Laboratory (NREL) study. In this study, we discuss the development of a semi-submersible floating offshore platform with a catenary mooring system to support a very large 13.2-MW wind turbine with 100-m blades. An iterative design process is applied to baseline models with Froude scaling in order to achieve preliminary static stability. Structural dynamic analyses are performed to investigate the performance of the new model using a finite element method approach for the tower and a boundary integral equation (panel) method for the platform. The steady-state response of the system under uniform wind and regular waves is first studied to evaluate the performance of the integrated system. Response amplitude operators (RAOs) are computed in the time domain using white-noise wave excitation; this serves to highlight nonlinear, as well as dynamic characteristics of the system. Finally, selected design load cases (DLCs) and the stochastic dynamic response of the system are studied to assess the global performance for sea states defined by wind fields with turbulence and long-crested irregular waves.Item Morphology Controlled Synthesis of SmMn₂O₅ Nanocrystals via a Surfactant-Free Route for Zn-Air Batteries(Elsevier B.V.) Yu, M.; Wei, Q.; Wu, M.; Wu, J.; Liu, J.; Zhang, G.; Sun, S.; Wang, Weichao; Wang, WeichaoDeveloping earth abundant and highly active electrocatalysts to overcome the sluggish oxygen reduction kinetics is one of the key toward the practical applications of air batteries with economic efficiency and high energy density. Herein, a shape-controlled synthesis of mullite SmMn₂O₅ is achieved through a surfactant-free one-step hydrothermal method. SmMn₂O₅ nanoparticles (SmMn₂O₅-NPs) and nanorods (SmMn₂O₅-NRs) are successfully synthesized and in half-cell tests, SmMn₂O₅-NRs perform enhanced oxygen reduction activity relative to SmMn₂O₅-NPs in terms of a more positive half-wave potential and reduced peroxide yield. Importantly, rechargeable zinc-air batteries constructed with SmMn₂O₅-NRs exhibit not only higher peak power density (217 mW cm⁻²) over commercial Pt/C catalyst (190 mW cm⁻²) but also excellent cycling stability during long-term charging-discharging test over 170 h. The facile synthesis of SmMn₂O₅-NRs together with the remarkable electrocatalytic performance endows mullite SmMn₂O₅ with great promise in replacing the precious metal as future catalysts for air batteries.