HVAC LCL filter Lagrange multipliers Lagrangian dual problem Lagrangian relaxation Liquid Rocket Engines PR controllers TWI Technology: general issues aerodynamic coefficients air-cooled condenser aircraft bioenergetics biomimetics energy saving and efficiency evaporative flight efficiency flight speed grey wolf optimizer grid-tied inverter hydro-thermal coordination passive damping propeller propulsive efficiency step-size update algorithm subgradient methods supercritical injection turboprop turbulence modeling water-cooled condenser