Methods, systems and apparatus for cleaning turbines, such as power generation turbines, are disclosed. The mounting portion and the pressing portion include a lower die contact portion and an upper die contact portion each formed into a shape along the bent shape of the bent material to come in contact with the bent material. The third lens and the fourth lens are made of plastic material and the following condition is satisfied:15. The side of the outer rim faces toward the rolling-lobe flexible member. In the case where the function of the measured exertion level is the difference between a short-term average and a long-term average of the measured exertion level, the lower rate limit is modulated as a function of the long-term average of the measured exertion level and maximum and minimum values of the long-term average of the measured exertion level during a defined extended time period. In some embodiments, the coating includes a low-maintenance film that includes both titanium oxide and tungsten oxide.