def get_element_mfrs(self, elements=None):
if elements is None:<EOL><INDENT>elements = self.material.elements<EOL><DEDENT>result = numpy.zeros(len(elements))<EOL>for compound in self.material.compounds:<EOL><INDENT>result += self.get_compound_mfr(compound) *stoich.element_mass_fractions(compound, elements)<EOL><DEDENT>return result<EOL>
Determine the mass flow rates of elements in the stream.

:returns: Array of element mass flow rates. [kg/h]