... terms of their subordinate relationship, establishes the relationship of the factors of different levels, compares the importance of the factors at the same level and then decides the order ... increase the temperature of the biogas digester due to the presence of abundant solar energy in these two areas. But the construction of a solar greenhouse enlarges the capital input. Therefore, ... corn stalk, cotton stalk, bean straw, potato stalks and the stalks of oil-bearing crops. The quantity of agricultural residues is estimated using the output of crops and their residue factors [15]....