y:'Symbol';font-style:normal;color:#010100;text-decoration:none;">&#183;</span><span style="color: #010100;">A </span><span style="font-weight: bold; color: #010100;">concentration source</span><span style="color: #010100;"> fixes the concentration of any external inflow entering the network at a node, such as flow from a reservoir or from a negative demand placed at a junction.</span></p><p style="text-indent: 0; padding-left: 0.1354in; margin: 0.0521in 0 0 0;"><span style="display:inline-block;width:0.135