People standing in front of mechanical equipment.
The people are by mechanical equipment.
standing in front of mechanical equipment also means  people are by mechanical equipment.
exists e1 s1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x3) & of(x3,x4) & n_equipment(x4) & a_mechanical(s1) & Theme(s1,x4) & n_front(x3) & Actor(e1,x2) & v_stand(e1) & (x1 = x2) & n_people(x1))
exists p1 x1.(n_people(x1) & exists s1 x2.(by(x1,x2) & n_equipment(x2) & a_mechanical(s1) & Theme(s1,x2)))