An adaptive RAKE receiving apparatus is constrained with at least one constraint for use in a mobile communication system. A reflective mask blank for EUV lithography, which comprises a substrate, and a reflective layer to reflect EUV light and an absorber layer to absorb EUV light, formed in this order on the substrate, wherein the absorber layer contains tantalum and hafnium, and in the absorber layer, the content of Hf is from 20 to 60 at. The method may further include choosing an angle between the left channel loudspeaker and the right channel loudspeaker, and determining from both the chosen angle and the chosen distance an optimal amount of transaural crosstalk compensation. Because of this, a pressure sensor or quantity sensor on a pump intake side is rendered unnecessary, and a simplification and reduction in cost of a feed water pump control device are possible.